Next Article in Journal
Large-Scale Non-Targeted Metabolomics Reveals Antioxidant, Nutraceutical and Therapeutic Potentials of Sorghum
Previous Article in Journal
Comparative Analysis of the Antioxidative and Hepatoprotective Activities of Dimethyl Diphenyl Bicarboxylate in Four Animal Models of Hepatic Injury
 
 
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Total Synthesis of Resvebassianol A, a Metabolite of Resveratrol by Beauveria bassiana

College of Pharmacy, Gachon University, 191 Hambakmoe-ro, Yeonsu-gu, Incheon 21936, Korea
*
Author to whom correspondence should be addressed.
Antioxidants 2021, 10(10), 1509; https://doi.org/10.3390/antiox10101509
Submission received: 22 August 2021 / Revised: 10 September 2021 / Accepted: 17 September 2021 / Published: 23 September 2021
(This article belongs to the Section Natural and Synthetic Antioxidants)

Abstract

:
Resveratrol is a well-known dietary polyphenol because it has a variety of beneficial biological activities. The fungus Beauveria bassiana is one of the most frequently used microorganisms for the biotransformation of polyphenols. Recently, resvebassianol A (2), a glycosylated metabolite of resveratrol by B. bassiana, was isolated and structurally elucidated. It was demonstrated to exhibit antioxidant, regenerative, and anti-inflammatory activities with no cytotoxicity. Here, we report the first total synthesis of resvebassianol A, 4′-O-β-(4‴-O-methylglucopyranosyl)resveratrol (2), and its regiomer, 3-O-β-(4‴-O-methylglucopyranosyl)resveratrol (3). Key reactions include (i) the construction of a stilbene core via a novel Heck reaction of aryl halides and styrenes, and (ii) glycosylation with unnatural methylglucopyranosyl bromide. The glycosylation step was carefully optimized by varying the bases and solvents. Resveratrol metabolites 2 and 3 were obtained at 7.5% and 6.3% of the overall yield, respectively.

1. Introduction

Resveratrol (1, trans-3,5,4-trihydroxystilbene) is an important dietary polyphenol and naturally occurring phytoalexin found in grapes, red wine, berries, peanuts, olive oil, etc. [1,2,3]. It is produced by plants in response to environmental stress and fungal attack through the induction of resveratrol synthetase [4,5]. Resveratrol was first isolated from the roots of the white hellebore lily (Veratrum grandiflorum O. Loes) in 1940 [6]. Most of the biological activities of resveratrol have been shown by its trans stilbene isomer, while the cis stilbene isomer also occurs naturally [7]. Resveratrol exerts numerous biological activities such as antioxidant, anti-infective, anti-inflammatory, anti-ischemic, cardioprotective, neuroprotective, anti-aging, anti-viral, anti-obesity, and anti-cancer effects [8,9,10,11,12,13,14,15,16,17,18]. Recently, it was revealed that its ability to activate various deacetylase enzymes (sirtuins) could be responsible for the various biological properties and delay aging [19,20].
Despite their pharmacological activities, various in vivo studies have shown that the potential of polyphenols is impaired by their insolubility in water, ultraviolet light instability, poor intestinal absorption, short half-life, rapid clearance, low bioavailability, and rapid metabolism [21,22]. The introduction of a glycosyl moiety on polyphenols not only helps to enhance the solubility of substrates but also reduces their toxicity, which ultimately increases the activity of biosynthetic intermediates [23]. Moreover, the sugar moiety of polyphenol glycosides might play a major role in their absorption, resulting in an acceptable concentration in the circulatory streams [24]. Polyphenols are subjected to enzymatic oxidation by polyphenol oxidases in plants, during food processing, and also after human consumption, which can be protected by glycosylation [25]. The incorporation of sugar moieties into different types of pharmacophores, natural products, or prodrugs has been proven to improve anti-cancer activities [26].
Several glycosyl derivatives of resveratrol have been recognized in the roots of Poligonum cuspidatum such as piceid (3-O-β-D-glucosyl resveratrol), resveratroloside (4′-O-β-D-glucosylresveratrol), and 4′-O-β-D-glucosyl piceatannol [27]. Piceid has been shown to exhibit a broad range of biological activities [28].
The fungus Beauveria bassiana is the most frequently used biocatalyst and has been used to transform more than 300 bioactive compounds [29,30]. For instance, B. bassiana ATCC 7159 has been used for the biotransformation of curvularin and kaempferol, leading to the production of new metabolites resulting from 4-O-methyl glucosylation of the substrate, and was highly selective among different hydroxyl groups in the same molecule [30]. Recently, resvebassianol A (2) shown in Figure 1, was identified through biotransformation of resveratrol by B. bassiana and exhibited important pharmacological activities such as inhibition of inflammatory cytokine expression and cell rejuvenation. Moreover, compared with resveratrol, resvebassianol A proved to be less toxic and more stable [31].
Several synthetic approaches for the formation of glycosidic bonds to phenolic OH in resveratrol have been reported. Direct coupling of resveratrol with a bromo-glucuronide donor was performed by Wang et al. for the synthesis of two glycoconjugates [32]. Coupling of resveratrol with glucuronyl bromide was performed using silver carbonate as an activator, in order to produce glucuronide-conjugated resveratrol in low yield, possibly due to the low solubility of resveratrol in organic solvents. Lucas et al. synthesized resveratrol 3-O-β-D-glucuronide by coupling a trichloroacetimidate glycosyl donor with protected resveratrol using TMSOTf and BF3.OEt2 as promoters [3]. Learmonth also synthesized two glucuronide conjugates of resveratrol, in which palladium-catalyzed Heck coupling of an iodo-O-β-D-glucuronate derivative and its corresponding styrene was adopted [33].
The structural uniqueness and natural resource scarcity of resvebassianol A for biological evaluation prompted us to develop an efficient synthetic method for the metabolite. In this study, we report the total synthesis of resvebassianol A (2), a metabolite of resveratrol by B. bassiana, and its regiomer, 3-O-β-(4‴-O-methylglucopyranosyl)resveratrol (3).

2. Materials and Methods

2.1. Chemical Reagents

All chemicals and solvents were reagent grade and were purchased from Sigma Aldrich (Saint Louis, MO, USA), TCI (Tokyo, Japan), and Alfa Aesar (Haverhill, MA, USA). All reagents were used directly without further purification.

2.2. Purification and Instrumentation

All reactions were carried out in an inert atmosphere in flame-dried glassware. Reactions were monitored by thin-layer chromatography using 0.25 mm silica gel plates and visualized using UV 254/286 nm. Flash chromatography was carried out using silica gel 60 (230–400 mesh, Merck, Darmstadt, Germany) as the stationary phase. 1H and 13C NMR spectra were recorded using a 600 MHz NMR spectrometer (Bruker, Billerica, MA, USA) with deuterochloroform (CDCl3), methanol-d4 (CD3OD), or DMSO-d6 (CD3)2SO. Data for 1H NMR spectra are reported as chemical shifts (multiplicity, coupling constants, integration), and multiplicities are reported as s = singlet, d = doublet, t = triplet, q = quartet, septet = septet, m = multiplet and/or multiple resonances, number of protons, and coupling constant (J). High-resolution mass spectra (HRMS) were recorded using electrospray ionization (ESI) mass spectroscopy on a JEOL JMS- 700 (FAB and EI) and an Agilent 6530 Q-TOF LC/MS/MS system (ESI).

2.3. General Experimental Procedure

2.3.1. Synthesis of Methyl 4, 6-O-Benzylidene-α-D-Glucopyranoside (13)

Methyl α-D-glucopyranoside 8 (10 g, 51.5 mmol) was dissolved in anhydrous N,N-dimethylformamide (100 mL) under a N2 atmosphere, p-toluene sulfonic acid (1.62 g, 9.4 mmol) was added, followed by the addition of benzaldehyde dimethyl acetal (9.2 mL, 61.8 mmol), and the solution was stirred under N2 for 16 h. After completion of the reaction, triethylamine (4 mL) was added to the reaction, which was then diluted with ethyl acetate. The organic layer was subsequently washed with saturated sodium bicarbonate and brine, dried over Na2SO4, and concentrated in vacuo. The residue was purified by silica gel column chromatography (methanol/dichloromethane = 30:1) to yield product 13 (12 g, 93%) as a white solid. 1H NMR (600 MHz, CDCl3) δ 7.49–7.47 (m, Ph, 2H), 7.36–7.34 (m, Ph, 3H), 5.49 (s, 1H), 4.70 (d, J = 3.9 Hz, 1H), 4.25 (dd, J = 6, 6 Hz, 1H), 3.87 (t, J = 9 Hz, 1H), 3.76–3.74 (m, 1H), 3.69 (t, J = 12, 1H), 3.57–3.53 (m, 2H), 3.43 (t, J = 12 Hz, 1H), 3.39 (s, 3H), 2.93 (d, J = 6 Hz, 1H); 13C NMR (151 MHz, CDCl3) δ 137.0, 129.2, 128.3, 126.4, 101.9, 99.9, 80.9, 72.7, 71.4, 68.9, 62.3, 55.5; HRMS (ESI): mass calcd for C14H18O6 [M + H]+, 283.1176; found, 283.1168.

2.3.2. Synthesis of Methyl 2,3-di-O-Benzyl-4,6-O-Benzylidene-α-D-Glucopyranoside (14)

Methyl 4,6-O-benzylidene-α-D-glucopyranoside 13 (11.5 g, 40.73 mmol) was dissolved in anhydrous N,N-dimethylformamide (100 mL) under a N2 atmosphere. The solution was cooled to 0 °C in an ice bath, after which NaH (60% dispersion in mineral oil, 4 g, 163 mmol) was added, and the reaction was stirred for 1 h at room temperature. The solution was cooled to 0 °C, and benzylbromide (14.5 mL, 122 mmol) was added dropwise. The solution was stirred at room temperature overnight, after which methanol (10 mL) was added, and the mixture was concentrated under reduced pressure. The residue was dissolved in CH2Cl2 (200 mL), washed with water (2 × 75 mL) and brine (1 × 75 mL), and dried over MgSO4. The residue was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:7) to yield product 14 (17.5 g, 92%) as a white solid compound. 1H NMR (600 MHz, CDCl3) δ 7.49 (d, J = 6, 2H), 7.39–7.21 (m, 13H), 5.54 (s, 1H), 4.91 (d, J = 12 Hz, 1H), 4.84 (dd, J = 12 Hz, 2H), 4.70 (d, J = 12 Hz, 1H), 4.60 (d, J = 6 Hz, 1H), 4.26 (dd, J = 12, 6 Hz, 1H), 4.05 (t, J = 9 Hz, 1H), 3.84–3.80 (m, 1H), 3.70 (t, J = 9 Hz, 1H), 3.60 (t, J = 9Hz, 1H), 3.55 (dd, J = 3 Hz, 1H), 3.39 (s, 3H); 13C NMR (151 MHz, CDCl3) δ 138.8, 138.2, 137.5, 129.0, 128.5, 128.4, 128.3, 128.2, 128.1, 128, 127.7, 126.1, 101.3, 99.3, 82.2, 79.2, 78.6, 75.4, 73.8, 69.1, 62.4, 55.4; HRMS (ESI): mass calcd for C28H30O6 [M + H]+, 463.2115; found, 463.2112.

2.3.3. Synthesis of Methyl 2,3,6-tri-O-Benzyl-α-D-Glucopyranoside (15)

Methyl 2,3-di-O-benzyl-4,6-O-benzylidene-α-D-glucopyranoside 14 (17.25 g, 38 mmol) was dissolved in anhydrous CH2Cl2 (100 mL) under a N2 atmosphere, and the solution was cooled to 0 °C. Et3SiH (30 mL, 186 mmol) and trifluoroacetic acid (14 mL, 186 mmol) were added, and the solution was stirred at 0 °C for 4 h. The reaction was quenched with Et3N and methanol. CH2Cl2 was added, and the solution was washed with water and brine, dried over MgSO4, filtered, and concentrated under reduced pressure. The mixture was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:4) to afford product 15 (12 g, 91%) as a colorless oil. 1H NMR (600 MHz, CDCl3) δ 7.37–7.26 (m, 15H), 5 (d, J = 12 Hz, 1H), 4.76 (dd, J = 12 Hz, 2H), 4.76–4.63 (m, 2H), 4.59 (d, J = 12 Hz, 1H), 4.54 (d, J = 12, 1H), 3.79 (t, J = 12, 18 Hz, 1H), 3.71–3.68 (m, 3H), 3.61 (t, J = 12, 18 Hz, 1H), 3.54 (dd, J = 6 Hz, 1H), 3.38 (s, 3H), 2.33 (s, 1H); 13C NMR (151 MHz, CDCl3) δ 138.8, 138.1, 138.0, 128.6, 128.5, 128.4, 128.1, 128.0, 128.0, 127.9, 127.7, 127.6, 98.2, 81.5, 79.6, 77.2, 77.0, 76.8, 75.4, 73.6, 73.2, 70.7, 69.9, 69.5, 55.3; HRMS (ESI): mass calcd for C28H32O6 [M + NH4]+, 482.2537; found, 487.2525.

2.3.4. Synthesis of Methyl 2,3,6-Tri-O-Benzyloxy-4-O-Methyl-α-D-Glucopyranoside (16)

NaH (60% dispersion in mineral oil, 1.5 g, 63 mmol) was added to a solution of methyl 2,3,6-tri-O-benzyloxy-α-D-glucopyranoside 15 (11.5 g, 25 mmol) in anhydrous N,N- dimethylformamide (100 mL) at 0 °C. The reaction mixture was stirred for 1 h at 0 °C, and methyl iodide (3.8 mL, 63 mmol) was added to the reaction mixture. The reaction mixture was stirred overnight at room temperature. The reaction was quenched with methanol and ice-cold water and then extracted with ethyl acetate. The collected organic layers were washed with brine, dried with Na2SO4, and concentrated under reduced pressure. The mixture was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:7) to yield product 16 (11.2 g, 95%) as a viscous liquid. 1H NMR (600 MHz, CDCl3) δ 7.39–7.26 (m, 5H), 4.93 (d, J = 10.8, 1H), 4.83–4.74 (m, 2H), 4.67–4.57 (m, 3H), 4.51 (d, J = 12.1 Hz, 1H), 3.86 (s, 1H), 3.66 (dd, J = 22.7, 7.1 Hz, 3H), 3.50 (dd, J = 9.7, 3.5 Hz, 1H), 3.46 (s, 3H), 3.37 (s, 3H), 3.33 (s, 1H); 13C NMR (151 MHz, CDCl3) δ 138.9, 138.2, 138.0, 128.4, 128.4, 128.3, 128.1, 128.0, 127.9, 127.8, 127.6, 127.6, 98.2, 82.1, 79.6, 79.4, 75.7, 73.5, 73.4, 70.1, 68.6, 60.7, 55.2; HRMS (ESI): mass calcd for C29H34O6 [M + NH4]+, 496.2694; found, 496.2688.

2.3.5. Synthesis of Methyl 4-O-Methyl-α-D-Glucopyranoside (17)

Pd (10%)/C (3 g) was added to a solution of methyl 2,3,6-Tri-O-benzyloxy-4-O-methyl-α-D-glucopyranoside 16 (11 g, 22 mmol) in anhydrous methanol (100 mL), and the mixture was stirred under an atmosphere of hydrogen at room temperature for 24 h. The catalyst was filtered out, and the solvents were removed under reduced pressure. The crude residue was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:1) to afford the viscous product 17 (4.6 g, 95%). 1H NMR (600 MHz, CD3OD) δ 4.69 (s, 1H), 3.78 (d, J = 11.7 Hz, 1H), 3.70 (dq, J = 12.2, 6.9, 4.4 Hz, 2H), 3.57 (s, 3H), 3.53–3.47 (m, 1H), 3.44 (d, J = 7.9 Hz, 1H), 3.40 (s, 3H), 3.10 (t, J = 9.3 Hz, 1H); 13C NMR (151 MHz, CD3OD) δ 99.7, 79.6, 73.7, 72.1, 71.2, 60.8, 59.5, 54.2; HRMS (ESI): mass calcd for C8H16O6 [M + H]+, 209.1020; found, 209.1033.

2.3.6. Synthesis of Methyl 2,3,6-tri-O-Acetyl-α-D-Glucopyranoside (18)

Compound 17 (4.5 g, 22 mmol) was dissolved in acetic anhydride (25 mL, 217 mmol) and pyridine (25 mL, 217 mmol) and stirred at room temperature for 12 h. After completion of the reaction, pyridine and acetic anhydride were removed in vacuo. The residue was dissolved in CH2Cl2 and washed with dilute HCl. The organic layer was collected, washed with brine, dried with MgSO4, and concentrated under reduced pressure. The mixture was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:4) to afford the viscous product 18 (5.1 g, 71%). 1H NMR (600 MHz, CDCl3) δ 5.50–5.42 (m, 1H), 4.88–4.79 (m, 2H), 4.35 (d, J = 10.0 Hz, 1H), 4.30–4.24 (m, 1H), 3.88–3.81 (m, 1H), 3.42 (d, J = 3.7 Hz, 3H), 3.39 (d, J = 3.9 Hz, 3H), 3.34 (dd, J = 12.6, 6.3 Hz, 1H), 2.12 (d, J = 3.9 Hz, 3H), 2.08 (d, J = 6.0 Hz, 6H); 13C NMR (150 MHz, CDCl3) δ 170.7, 170.4, 169.8, 96.8, 77.8, 71.9, 71.1, 68.2, 62.7, 60.1, 55.3, 20.9, 20.8, 20.8; HRMS (ESI): mass calcd for C14H22O9 [M + NH4]+, 352.1602; found, 352.1605.

2.3.7. Synthesis of 1,2,3,6-Tetra-O-Acetyl-4-O-Methyl-α-D-Glucopyranoside (19)

To a stirred solution of 18 (5 g, 15 mmol) in acetic anhydride (50 mL) at 0 °C, boron trifluoride ether (2 mL, 15 mmol) was added. The solution was warmed to room temperature and allowed to stir for 2 h. Then, the solution was poured into an ice-cold saturated solution of NaHCO3 and extracted with ethyl acetate. The combined organic layers were separated, dried over MgSO4, and concentrated under reduced pressure. The mixture was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:2) to yield the viscous product 19 (4.1 g, 75%). 1H NMR (600 MHz, CDCl3) δ 6.25 (t, J = 3.1 Hz, 1H), 5.45 (ddd, J = 10.2, 9.2, 2.4 Hz, 1H), 5.0 (ddd, J = 10.3, 3.7, 2.7 Hz, 1H), 4.35–4.31 (m, 1H), 4.28–4.24 (m, 1H), 3.99–3.92 (m, 1H), 3.45 (d, J = 2.3 Hz, 3H), 3.43 (d, J = 2.2 Hz, 1H), 2.16 (d, J = 2.3 Hz, 3H), 2.12–2.09 (m, 6H), 2.01 (d, J = 2.4 Hz, 3H); 13C NMR (151 MHz, CDCl3) δ 170.6, 170.0, 169.9, 169.0, 89.2, 71.7, 71.0, 69.6, 62.3, 60.5, 20.9, 20.8, 20.5; HRMS (ESI): mass calcd for C15H22O10 [M + NH4]+, 380.1551; found, 380.1545.

2.3.8. Synthesis of 2,3,6-O-Triacetyl-4-O-Methylglucopyranosyl bromide (6)

A solution of HBr (10 mL, 33 wt% in acetic acid) was added dropwise to a stirred solution of compound 19 (3.7 g, 10 mmol) in CH2Cl2 (50 mL) at 0 °C. The solution was stirred at room temperature for 4 h. After completion of the reaction, the reaction mixture was quenched carefully with ice water and diluted with CH2Cl2 and water. The organic layer was separated and washed with saturated NaHCO3 and brine. The organic layer was dried over MgSO4, filtered, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethylacetate/n-hexane 1:4) to yield the light yellow liquid 6 (2.8 g, 73%). This compound was unstable, and after drying, it was used for further reactions. 1H NMR (600 MHz, CDCl3) δ 6.53 (d, 1H, J = 3.7 Hz), 5.57 (t, J = 9.6 Hz, 1H), 4.75 (dd, J = 10.0, 3.8 Hz, 1H), 4.39 (d, J = 12.4 Hz, 1H), 4.31 (dd, J = 12.4, 4.0 Hz, 1H), 4.15 (d, J = 10.1 Hz, 1H), 3.45 (d, J = 9.7 Hz, 4H), 2.12 (d, J = 6.6 Hz, 6H), 2.10 (s, 3H); 13C NMR (151 MHz, CDCl3) δ 170.5, 170.1, 169.6, 86.8, 76.6, 73.2, 71.8, 70.9, 61.8, 60.3, 20.9, 20.8, 20.7.

2.3.9. Synthesis of 3,5-bis(tert-Butyldimethylsilyloxy) Benzaldehyde (20)

To a well-stirred solution of 3,5-dihydroxybenzaldehyde 9 (2 g, 14.48 mmol) and DIPEA (5.3 mL, 43.4 mmol) in N,N- dimethylformamide (20 mL), tert-butylchlorodimethylsilane (6.55 g, 43.4 mmol) was added at 0 °C, and the reaction mixture was stirred for 3 h at room temperature. The reaction mixture was diluted with CH2Cl2 and washed with saturated aqueous NaCl, and the combined organic layers were dried over anhydrous Na2SO4 and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:20) to afford 20 (5.1 g, 96%) as a colorless oil. 1H NMR (600 MHz, CDCl3) δ 9.9 (s, 1H), 7.0 (s, 2H), 6.6 (s, 1H), 1.0 (s, 18H), 0.2 (s, 12H); 13C NMR (151 MHz, CDCl3) δ 191.9, 157.3, 138.3, 118.4, 114.4, 25.7, 25.6, 18.2; HRMS (ESI): mass calcd for C19H34O3Si2[M + H]+, 367.2119; found, 367.2113.

2.3.10. Synthesis of (5-Vinyl-1,3-Phenylene)bis(oxy)bis(tert-Butyldimethylsilane (21)

A mixture of methyltriphenylphosphonium bromide (7.3 g, 20.4 mmol) and potassium tert-butoxide (2.2 g, 20 mmol) in anhydrous THF was refluxed for 1 h for in situ generation of methylenetriphenylphosphorane. Upon returning to room temperature, a solution of 3,5-di(tert-butyldimethylsilyloxy) benzaldehyde 20 (5 g, 13.6 mmol) in anhydrous THF was added dropwise, and the reaction was heated to reflux overnight. After completion of the reaction, ethyl acetate was added, and the solution was washed with water, dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:25) to yield product 21 (3.4 g, 68%) as a colorless oil. 1H NMR (600 MHz, CDCl3) δ 6.6 (dd, J = 17.4, 10.9 Hz, 1H), 6.5 (s, 2H), 6.3 (s, 1H), 5.7 (d, J = 17.5 Hz, 1H), 5.2 (d, J = 10.9 Hz, 1H), 1.0 (s, 18H), 0.2 (s, 12H); 13C NMR (151 MHz, CDCl3) δ 156.6, 139.4, 136.7, 113.9, 111.7, 111.5, 25.7, 25.7, 18.2; HRMS (ESI): mass calcd for C20H36O2Si2[M + H]+, 365.2327; found, 365.2333.

2.3.11. Synthesis of 5-Vinylbenzene-1,3-diol, [3,5-Dihdroxy Styrene] (12)

To a solution of (5-vinyl-1,3-phenylene) bis(oxy)bis(tert-butyldimethylsilane) 21 (3 g, 8.2 mmol) in anhydrous THF (15 mL), TBAF (4 mL, 14 mmol) was added at 0 °C, and the reaction mixture was stirred for 3 h at room temperature. The volume was reduced by rotary evaporation, and ethyl acetate was added. The organic layer was washed with water, dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:1) to yield product 12 (1.2 g, 92%) as a viscous pale oil. 1H NMR (600 MHz, CD3OD) δ 6.6 (dd, J = 17.4, 11.0 Hz, 1H), 6.4 (s, 2H), 6.2 (s, 1H), 5.6 (d, J = 17.6 Hz, 1H), 5.1 (d, J = 10.8 Hz, 1H); 13C NMR (151 MHz, CD3OD) δ 158.2, 139.6, 137.0, 112.3, 104.4, 101.8, 35.6, 35.2; HRMS (ESI): mass calcd for C8H8O2[M + H]+, 137.0597; found, 137.0621.

2.3.12. Synthesis of 5-Vinyl-1,3-Phenylene Diacetate (3,5-Diacetoxystyrene) (5)

Acetic anhydride (2 mL, 22 mmol) was added dropwise to a solution of compound 12 (1 g, 7.3 mmol), pyridine (1.9 mL, 22 mmol), and DMAP (26 mg, 0.219 mmol) in CH2Cl2 at 0 °C. The reaction mixture was stirred at room temperature for 12 h. The solution was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:4) to yield 5-vinyl-1,3-phenylene diacetate 5 (1.12 g, 70%) as a clear oil. 1H NMR (600 MHz, CDCl3) δ 7.0 (s, 2H), 6.8 (s, 1H), 6.6 (dd, 1H, J = 17.1, 11.2 Hz), 5.7 (d, 1H, J = 17.5 Hz), 5.3 (d, 1H, J = 10.8 Hz), 2.3 (s, 6H); 13C NMR (151 MHz, CDCl3) δ 169.0, 151.2, 139.9, 135.3, 116.7, 115.9, 114.7, 21.0; HRMS (ESI): mass calcd for C12H12O4[M + NH4]+, 238.1074; found, 238.1085.

2.3.13. Synthesis of 4-Iodophyenyl Acetate (11)

To a well-stirred mixture of 4- iodophenol 7 (2 g, 9 mmol) in dry pyridine (6 mL), acetic anhydride (1.75 mL, 18 mmol) was added at room temperature under N2. The mixture was then stirred for 12 h. After completion of the reaction, water was added and extracted with CH2Cl2. The organic layer was dried over MgSO4 and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (dichloromethane 100%) to yield product 11 (2.2 g, 95%) as a white solid. 1H NMR (600 MHz, CDCl3) δ 7.7–7.6 (m, 2H), 6.9–6.8 (m, 2H), 2.3 (s, 3H); 13C NMR (151 MHz, CDCl3) δ 169.1, 150.5, 138.5, 123.8, 89.9, 21.1; HRMS (ESI): mass calcd for C8H7 IO2[M + NH4]+, 279.9827; found, 279.9826.

2.3.14. Synthesis of 4-Iodophenyl-2′,3′,6′-O-triacetyl-4′-O-Methylglucopyranoside (4)

To a mixture of iodophenol 7 (259 mg, 1.9 mmol) and 2,3,6-O-triacetyl-4-methylglucopyranosyl bromide 6 (730 mg, 1.9 mmol) in CHCl3, benzyltributylammonium chloride (60 mg, 0.19 mmol) and potassium carbonate (665 mg, 4.8 mmol) were added and stirred at room temperature for 24 h. The reaction mixture was neutralized with 1 N HCl, and the organic layer was separated. The organic layer was washed with water-saturated NaHCO3 and brine, dried over MgSO4, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:4) to yield product 4 (565 mg, 57%) as a white solid. 1H NMR (600 MHz, CDCl3) δ 7.56–7.54 (m, 2H), 6.74 (dd, J = 8.9, 2.7 Hz 2H), 5.22 (t, J = 9.3 Hz, 1H), 5.12 (dd, J = 9.6, 7.7 Hz, 1H), 4.98 (d, J = 7.8 Hz, 1H), 4.38 (dd, J = 12.0, 2.4 Hz, 1H), 4.24 (dd, J = 12.1, 5.6 Hz, 1H), 3.67 (ddd, J = 10.1, 5.7, 2.4 Hz, 1H), 3.43 (d, J = 2.5 Hz, 4H), 2.08 (d, J = 8.5 Hz, 6H), 2.03 (d, J = 2.5 Hz, 3H); 13C NMR (151 MHz, CDCl3) δ 170.5, 170.0, 169.6, 156.7, 138.4, 119.2, 98.7, 86.0, 77.5, 74.7, 73.1, 71.5, 62.7, 60.5, 20.9, 20.8, 20.7; HRMS (ESI): mass calcd for C19H23IO9[M + NH4]+, 540.0725; found, 540.0712.

2.3.15. Synthesis of (E)-1″-(3,5-Diacetoxy)-2″-(4′-O-2‴,3‴,6‴-Triacetyl-4‴-O-Methyl-β-D Glucopyranosidophenyl) Ethene (22)

To a solution of 3,5-diacetoxystyrene 5 (235 mg, 1.07 mmol) and compound 4 (560 mg, 1.07 mmol) in acetonitrile, palladium(II) acetate (0.012 mg, 0.053 mmol), benzyltriethylammonium chloride (243 mg,1.07 mmol), and tributylamine (0.68 mL, 2.9 mmol) were added and stirred at 100 °C for 2 h, N2. After 2 h, the mixture was cooled to room temperature, filtered through a short Celite pad, and then evaporated to dryness. The residue was taken up in dichloromethane, washed with diluted HCl, water, and brine, dried over anhydrous MgSO4, filtered, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:2) to yield compound 22 (361 mg, 55%) as a white crystal. 1H NMR (600 MHz, CDCl3) δ 7.41 (d, J = 8.5 Hz, 2H), 7.10 (s, 2H), 7.02 (d, J = 16.2 Hz, 1H), 6.97 (d, J = 8.5 Hz, 2H), 6.91 (d, J = 16.2 Hz, 1H), 6.80 (s, 1H), 5.26 (t, J = 9.3 Hz, 1H), 5.17 (t, J = 8.7 Hz, 1H), 5.07 (d, J = 7.8 Hz, 1H), 4.42 (d, J = 11.9 Hz, 1H), 4.29 (dd, J = 11.9, 5.4 Hz, 1H), 3.74–3.68 (m, 1H), 3.46 (s, 4H), 2.30 (s, 6H), 2.11 (d, J = 5.5 Hz, 6H), 2.06 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 170.6, 170.1, 169.7, 169.0, 156.8, 151.3, 139.7, 131.9, 129.7, 127.9, 126.0, 117.1, 116.8, 114.2, 98.7, 77.6, 74.8, 73.1, 71.6, 62.7, 60.5, 21.1, 20.9, 20.8, 20.7; HRMS (ESI): mass calcd for C31H34O13[M + NH4] +, 632.2338; found, 632.2342.

2.3.16. Synthesis of 4′-O-β- (4‴-O-Methylglucopyranosyl)Resveratrol (2)

Compound 22 (350 mg, 0.58 mmol) was dissolved in methanol (20 mL) and 0.2 M methanolic solution of sodium methoxide (20 mL). The resulting mixture was stirred for 1 h at room temperature. After completion of the reaction, the mixture was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (methanol/dichloromethane = 1:8) to obtain the final compound 2 (195 mg, 85%) as a white powder. 1H NMR (600 MHz, (CD3)2CO) δ 8.23 (s, 2H), 7.50 (d, J = 8.3 Hz, 2H), 7.04 (d, J = 7.6 Hz, 3H), 6.97 (s, 1H), 6.56 (s, 2H), 6.28 (s, 1H), 4.96 (d, J = 7.7 Hz, 1H), 4.64 (s, 1H), 4.40 (d, J = 3.4 Hz, 1H), 3.84 (dd, J = 10.8, 4.5 Hz, 1H), 3.80–3.75 (m, 1H), 3.70 (dd, J = 11.7, 5.1 Hz, 1H), 3.63 (dd, J = 8.8, 3.3 Hz, 1H), 3.57 (s, 3H), 3.51–3.43 (m, 2H), 3.31 (d, J = 5.2 Hz, 1H), 3.22 (t, J = 9.3 Hz, 1H). 13C NMR (151 MHz, (CD3)2CO) δ 158.7, 157.5, 139.7, 131.5, 127.7, 127.5, 127.3, 116.6, 104.9, 102.0, 100.6, 79.2, 77.1, 76.1, 74.0, 61.2, 59.7; HRMS (ESI): mass calcd for C21H24O8[M + H]+, 405.1544; found, 405.1551.

2.3.17. Synthesis of 3-Hydroxy-5-Vinylphenyl-2′,3′,6′-tri-O-Acetyl-4′-O-Methyl-β-D-Glucopyranoside (10)

To a solution of dihydroxystyrene 12 (248 mg, 1.8 mmol) and 2,3,6-O-triacetyl-4 methylglucopyranosyl bromide 6 (700 mg, 1.8 mmol) in CHCl3, benzyltributylammonium chloride (56 mg, 0.18 mmol) and potassium carbonate (636 mg, 4.6 mmol) were added and stirred at room temperature for 24 h. The reaction mixture was neutralized with 1 N HCl, and the organic layer was separated. The organic layer was washed with saturated NaHCO3 and brine, dried over MgSO4, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:2) to yield product 10 (320 mg, 40%) as a white product. 1H NMR (600 MHz, CDCl3) δ 6.59 (d, J = 17.1 Hz, 3H), 6.42 (s, 1H), 6.04 (s, 1H), 5.69 (d, J = 17.5 Hz, 1H), 5.25–5.23 (m, 2H), 5.13 (t, J = 8.6 Hz, 1H), 5.02 (d, J = 7.7 Hz, 1H), 4.42 (d, J = 11.8 Hz, 1H), 4.26 (dd, J = 11.7, 5.6 Hz, 1H), 3.71–3.69 (m, 1H), 3.45 (d, J = 12.0 Hz, 4H), 2.10 (d, J = 10.5 Hz, 6H), 2.05 (s, 3H); 13C NMR (151 MHz, CDCl3) δ 170.3, 170.0, 158.1, 157.0, 140.0, 136.2, 114.9, 108.2, 107.1, 104.1, 98.7, 77.7, 74.8, 73.0, 71.7, 62.8, 60.5, 20.9, 20.8, 20.7; HRMS (ESI): mass calcd for C21H26O10[M + NH4]+, 456.1864; found, 456.1875.

2.3.18. Synthesis of 3-Acetoxy-5-Vinylphenyl-2′,3′,6′-tri-O-Acetyl-4′-O-Methyl-β-D-Glucopyranoside (23)

Compound 10 (310 mg, 0.7 mmol) in CH2Cl2 (5 mL) at room temperature was added to pyridine (0.1 mL, 1.06 mmol) and 4-dimethylaminopyridine (0.001 mg), and acetic anhydride (0.1 mL, 1.06 mmol) was added dropwise. The resulting mixture was stirred for 1 h. The mixture was diluted with CH2Cl2 and water. The organic phase was separated and washed with dilute hydrochloric acid, water, and brine, dried over anhydrous MgSO4, filtered, and dried under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:4) to yield product 23 (288 mg, 85%) as a white solid. 1H NMR (600 MHz, CDCl3) δ 6.86 (dd, J = 30.6, 2.0 Hz, 2H), 6.65–6.56 (m, 2H), 5.74–5.68 (m, 1H), 5.31–5.20 (m, 2H), 5.14 (ddt, J = 10.5, 7.8, 1.1 Hz, 1H), 5.05 (d, J = 7.7 Hz, 1H), 4.40 (dq, J = 12.0, 1.6 Hz, 1H), 4.27–4.20 (m, 1H), 3.75–3.68 (m, 1H), 3.47–3.39 (m, 5H), 2.27 (dd, J = 2.4, 1.1 Hz, 3H), 2.09 (dd, J = 2.3, 1.1 Hz, 3H), 2.07 (dd, J = 2.3, 1.1 Hz, 3H), 2.04 (dd, J = 2.3, 1.1 Hz, 3H); 13C NMR (151 MHz, CDCl3) δ 170.6, 170.0, 169.7, 169.1, 157.5, 151.5, 140.0, 135.6, 115.6, 114.2, 112.1, 109.8, 98.6, 77.7, 74.7, 73.1, 71.5, 62.9, 60.4, 21.1, 20.9, 20.7, 20.7; HRMS (ESI): mass calcd for C23H28O11[M + NH4]+, 498.1970; found, 498.1985.

2.3.19. Synthesis of (E)-1″-(3-Acetoxy-5-O-2‴,3‴,6‴-Triacetyl-4‴-O-Methyl-β-D Glucopyranosidophenyl)- 2″-(4′-Acetoxyphenyl) Ethene (24)

To a solution of 4-iodophenylacetate 11 (147 mg, 0.56 mmol), compound 23 (270 mg, 0.56 mmol) in acetonitrile was added with palladium(II) acetate (0.006 mg, 0.028 mmol), benzyltriethylammonium chloride (128 mg, 0.56 mmol), and tributylamine (0.36 mL, 1.5 mmol) and stirred at 100 °C for 2 h under nitrogen. After 2 h, the mixture was cooled to room temperature, filtered through a short Celite pad, and then evaporated to dryness. The residue was taken up in dichloromethane, washed with diluted hydrochloric acid, water, and brine, dried over anhydrous MgSO4, filtered, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/n-hexane = 1:2) to yield product 24 (275 mg, 80%) as a white crystal. 1H NMR (600 MHz, CDCl3) δ 7.5 (d, J = 8.0 Hz, 2H), 7.1–7.0 (m, 3H), 7.0–6.9 (m, 3H), 6.6 (s, 1H), 5.3 (t, J = 9.2 Hz, 1H), 5.2 (t, J = 8.5 Hz, 1H), 5.1 (d, J = 7.6 Hz, 1H), 4.4 (d, J = 11.9 Hz, 1H), 4.3 (dd, J = 11.4, 5.8 Hz, 1H), 3.7 (s, 1H), 3.5 (s, 4H), 2.3 (s, 6H), 2.1 (s, 3H), 2.1 (s, 6H); 13C NMR (151 MHz, CDCl3) δ 170.6, 170.1, 169.7, 169.0, 156.8, 151.3, 139.7, 131.9, 129.8, 127.9, 126.0, 117.1, 116.8, 114.2, 98.7, 77.6, 74.8, 73.1, 71.6, 62.7, 60.5, 21.1, 20.9, 20.8, 20.7; HRMS (ESI): mass calcd for C31H34O13[M + H]+, 637.1999; found, 637.2014.

2.3.20. Synthesis of 3-O-β-(4‴-O-Methylglucopyranosyl) Resveratrol (3)

Compound 24 (260 mg, 0.64 mmol) was dissolved in methanol (20 mL), and 0.2 M methanolic solution of sodium methoxide (20 mL) was added at room temperature. The resulting mixture was stirred for 1 h. The mixture was concentrated to dryness under reduced pressure. The residue was purified by silica gel column chromatography (methanol/dichloromethane = 1:8) to yield product 3 (217 mg, 84%) as a white powder. 1H NMR (600 MHz, (CD3)2CO) δ 7.36 (d, J = 7.9 Hz, 2H), 7.03 (d, J = 16.3 Hz, 1H), 6.85 (d, J = 16.3 Hz, 1H), 6.79 (d, J = 8.1 Hz, 2H), 6.72 (s, 1H), 6.64 (s, 1H), 6.41 (s, 1H), 4.86 (d, J = 7.7 Hz, 1H), 3.81 (d, J = 12.0 Hz, 1H), 3.65 (dd, J = 12.0, 4.6 Hz, 1H), 3.59 (t, J = 9.0 Hz, 1H), 3.52 (s, 3H), 3.46–3.37 (m, 2H), 3.16 (t, J = 9.3 Hz, 1H); 13C NMR (151 MHz, (CD3)2CO) δ 159.3, 158.8, 157.7, 139.9, 128.7, 127.9, 125.4, 115.6, 107.3, 105.3, 102.9, 100.8, 79.2, 77.1, 76.1, 74.1, 61.2, 59.6; HRMS (ESI): mass calcd for C21H24O8[M + NH4]+, 405.1544; found, 405.1551. The spectra of the above mentioned compounds is displayed in the part of Supplemental Material.

3. Results and Discussion

3.1. Retrosynthesis

Metabolite 2 and its regiomer 3 consist of a glycone attached to the aglycone moiety. The glycone moiety is 4-O-methyl glucopyranose, whereas the aglycone is a functional resveratrol featuring a stilbene core with a polyhydroxy group. Metabolite 2 is a structure in which 4-O-methylglucopyranose is attached to the 7-position hydroxyl group of resveratrol, whereas its regiomer 3 consists of a glycosyl moiety attached to the 3-position hydroxyl group of resveratrol. The synthesis of both metabolites involves a glycosylation reaction that introduces methylated glucose as the core reaction and the Heck reaction to form a stilbene skeleton [34].
Scheme 1 and Scheme 2 provide a retrosynthetic methodology for the synthesis of both metabolites 2 and 3. Stilbene moiety 2 and its regiomer 3 were constructed via palladium-catalyzed Heck coupling. The rate-limiting step of the glycosylation reaction was performed with selectively protected compound 6 and commercially available iodophenol 7. Compound 10 was obtained from the glycosylation of compound 6 and styrene 12, which was synthesized from readily available dihydroxy benzaldehyde 9.

3.2. Chemistry

The reaction commenced with the preparation of the glycosyl donor, 4-O-methylglycopyranosyl bromide 6, as shown in Scheme 3, which involves eight steps from commercially available methyl-α-D-glucopyranoside 8. Regioselective protection of 4, 6-diol from the starting material was accomplished by the introduction of a 4,6-O-benzylidene group using benzaldehyde dimethyl acetal under acidic conditions, yielding protected compound 13. 2,3-Di-O-benzylation of 13 generated 14 using NaH and BnBr. Further regioselective opening of the benzylidene ring of intermediate 14 was conducted with the help of triethylsilane (TES) and trifluoroacetic acid (TFA) to obtain alcohol 15 [35]. Methylation of compound 15 with NaH and MeI in N, N-dimethylformamide yielded product 16, followed by hydrogenolysis to yield product 17. Acetylation of the hydroxy groups of 17 was performed using pyridine and acetic anhydride to yield 18, followed by the replacement of an anomeric methoxy group with an acetoxy group using boron trifluoride diethyl etherate to yield 19. Finally, grafting of the anomeric acetoxy group was performed to incorporate bromine using HBr (33% in acetic acid) to yield acylated glycosyl bromide 6 at 73% [36]. As the final compound, 4-O-methylglucopyranosyl bromide 6, has poor chemical stability, it is suitable to obtain a large amount of acetate compound 19 and synthesize 6 immediately when necessary.
3,5-Dihydroxystyrene 12 and 3,5 diacetoxyystyrene 5 were synthesized from commercially available 3,5-dihydroxy benzaldehyde 9 according to Scheme 4. Protection of the hydroxy group of 9 with TBDMS yielded 20, and the Wittig reaction yielded olefin 21 using methyltriphenylphosphonium bromide under basic conditions. The TBDMS group in intermediate 21 was removed using tetrabutylammonium fluoride (TBAF) to furnish dihydroxy styrene 12, and further acetylation of both hydroxy groups resulted in 12 at 70% yield.
After obtaining 6 and 12, the next target was to synthesize substrates 4 and 10, which participate in the Heck reaction for the synthesis of the stilbene core.
We performed glycosylation of both iodophenol 7 and dihydroxystyrene 12 separately with 4-O-methylglycopyranosyl bromide 6 under different reaction conditions, as shown in Table 1 and Table 2. Using Ag2CO3 in acetonitrile produced low-yield glycoside products 4 and 10 up to 16% and 19%, respectively. We attempted to improve glycosylation using a phase transfer catalyst (TBAB) in a two-phase system (aqueous NaOH and K2CO3) in CHCl3. Unfortunately, the reaction yielded trace amounts. The reaction was incomplete, and the substrate was recovered for reuse. Bromide compound 6 can be decomposed into glycal by an alkaline water phase and phenoxide anion [37]. Therefore, excess use of water in the reaction lowers the yield of the compound. After utilizing several conditions (Table 1 and Table 2), the glycosylation reaction under the phase transfer catalyst BnNBu3Cl and K2CO3 as a base at room temperature yielded product 4 at 57% yield. The desired mono-glucosylated product 10 was obtained at 40% yield along with the undesired di-glucosylated product as a mixture, which was separated by column chromatography.
Aryl iodide 7 was the choice for palladium-catalyzed Heck coupling because of its greater reactivity over other aryl halides.
The palladium-catalyzed Heck reaction between glycosylated compounds 4 and 5 under (Pd(OAc)2, BnEt3N+Cl, Bu3N) in warm acetonitrile produced 22 at 55% yield. Deprotection of the acetyl protecting groups of 22 under a methanolic solution of sodium methoxide resulted in metabolite 2 at 85% yield.
The hydroxy group of glycosylated product 10 was protected by acetylation to yield 23. Similar to Scheme 5, the protected product 23 undergoes a palladium-catalyzed Heck reaction with 4-iodophenyl acetate 11 to build styrene compound 24 at 80% yield. Finally, basic hydrolysis of the acetyl protecting groups under a methanolic solution of sodium methoxide afforded another metabolite, 3, at 84% yield (Scheme 6).

4. Conclusions

In conclusion, an efficient total synthesis was performed for the preparation of resvebassianol A (2, a metabolite of resveratrol by Beauveria bassiana) and its regiomer (3) through glycosylation and a palladium-catalyzed Heck reaction. Resvebassianol A and regiomer 3 were synthesized in 11 and 12 linear steps, with overall yields of 7.5% and 6.3%, respectively. Incorporation of 4-O methyl glyosyl was performed through the glycosylation reaction and was optimized using a phase transfer catalyst with varying bases. This resulted in an elevated yield of up to 40% and 57%, respectively. Thus, this method can be helpful for the synthesis of metabolites that are difficult to obtain from plant sources and through microbial biotransformation. This strategy can also be used for the synthesis of other related metabolites.

Supplementary Materials

The following are available online at https://www.mdpi.com/article/10.3390/antiox10101509/s1, Figure S1: 1H-NMR (600 MHz, CDCl3) of compound 13, Figure S2: 13C-NMR (150 MHz, CDCl3) of compound 13, Figure S3: 1H-NMR (600 MHz, CDCl3) of compound 14, Figure S4: 13C-NMR (150 MHz, CDCl3) of compound 14, Figure S5: 1H-NMR (600 MHz, CDCl3) of compound 15, Figure S6: 1C-NMR (150 MHz, CDCl3) of compound 15, Figure S7: 1H-NMR (600 MHz, CDCl3) of compound 16, Figure S8: 13C-NMR (150 MHz, CDCl3) of compound 16, Figure S9: 1H-NMR (600 MHz, CD3OD-d4) of compound 17, Figure S10: 1H-NMR (600 MHz, CD3OD-d4) of compound 17, Figure S11: 1H-NMR (600 MHz, CDCl3) of compound 18, Figure S12: 13C-NMR (150 MHz, CDCl3) of compound 18, Figure S13: 1H-NMR (600 MHz, CDCl3) of compound 19, Figure S14: 13C-NMR (150 MHz, CDCl3) of compound 19, Figure S15: 1H-NMR (600 MHz, CDCl3) of compound 6, Figure S16: 13C-NMR (150 MHz, CDCl3) of compound 6, Figure S17: 1H-NMR (600 MHz, CDCl3) of compound 20, Figure S18: 13C-NMR (150 MHz, CDCl3) of compound 20, Figure S19: 1H-NMR (600 MHz, CDCl3) of compound 21, Figure S20: 13C-NMR (150 MHz, CDCl3) of compound 21, Figure S21: 1H-NMR (600 MHz, CD3OD-d4) of compound 12, Figure S22: 13C-NMR (150 MHz, CD3OD-d4) of compound 12, Figure S23: 1H-NMR (600 MHz, CDCl3) of compound 5, Figure S24: 13C-NMR (150 MHz, CDCl3) of compound 5, Figure S25: 1H-NMR (600 MHz, CDCl3) of compound 11, Figure S26: 13C-NMR (150 MHz, CDCl3) of compound 11, Figure S27: 1H-NMR (600 MHz, CDCl3) of compound 4, Figure S28: 13C-NMR (150 MHz, CDCl3) of compound 4, Figure S29: 1H-NMR (600 MHz, CDCl3) of compound 22, Figure S30: 13C-NMR (150 MHz, CDCl3) of compound 22, Figure S31: 1H-NMR (600 MHz, (CD3)2CO)) of compound 2, Figure S32: 13C-NMR (150 MHz, (CD3)2CO) of compound 2, Figure S33: 1H-NMR (600 MHz, CDCl3) of compound 10, Figure S34: 13C-NMR (150 MHz, CDCl3) of compound 10, Figure S35: 1H-NMR (600 MHz, CDCl3) of Compound 23, Figure S36: 13C-NMR (151 MHz, CDCl3) of Compound 23, Figure S37: 1H-NMR (600 MHz, CDCl3) of compound 24, Figure S38: 13C-NMR (150 MHz, CDCl3) of compound 24, Figure S39: 1H-NMR (600 MHz, (CD3)2CO) of compound 3, Figure S40: 13C-NMR (150 MHz, (CD3)2CO) of compound 3.

Author Contributions

Writing—conceptualization for the manuscript, D.S.; writing—original draft preparation, review, and editing, O.D. and D.S.; funding acquisition, D.S. All authors have read and agreed to the published version of the manuscript.

Funding

This study was funded by the National Research Foundation of Korea (NRF-2021R1A2C1012280) and the intramural research program of Gachon University (GCU-2018-0676).

Institutional Review Board Statement

Not Applicable.

Informed Consent Statement

Not Applicable.

Data Availability Statement

Data is contained within the article or supplementary material.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Jang, M.; Cai, L.; Udeani, G.O.; Slowing, K.V.; Thomas, C.F.; Beecher, C.W.W.; Fong, H.H.S.; Farnsworth, N.R.; Kinghorn, A.D.; Mehta, R.G.; et al. Cancer Chemopreventive Activity of Resveratrol, a Natural Product Derived from Grapes. Science 1997, 275, 218–220. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  2. Wang, Y.; Catana, F.; Yang, Y.; Roderick, R.; van Breemen, R.B. An LC-MS Method for Analyzing Total Resveratrol in Grape Juice, Cranberry Juice, and in Wine. J. Agric. Food Chem. 2002, 50, 431–435. [Google Scholar] [CrossRef] [PubMed]
  3. Lucas, R.; Alcantara, D.; Morales, J.C. A concise synthesis of glucuronide metabolites of urolithin-B, resveratrol, and hydroxytyrosol. Carbohydr. Res. 2009, 344, 1340–1346. [Google Scholar] [CrossRef] [PubMed]
  4. Fritzemeier, K.-H.; Kindl, H. Coordinate induction by UV light of stilbene synthase, phenylalanine ammonia-lyase and cinnamate 4-hydroxylase in leaves of vitaceae. Planta 1981, 151, 48–52. [Google Scholar] [CrossRef]
  5. Schultz, T.P.; Boldin, W.D.; Fisher, T.H.; Nicholas, D.D.; Mcmurtrey, K.D.; Pobanz, K. Structure-fungicidal properties of some 3- and 4-hydroxylated stilbenes and bibenzyl analogues. Phytochemistry 1992, 31, 3801–3806. [Google Scholar] [CrossRef]
  6. Takaoka, M. Of the phenolic substrate of hellebore (Veratrum grandiflorum Loes. fil.). J. Fac. Sci. Hokkaido Imper. Univ. 1940, 3, 1–16. [Google Scholar]
  7. Quideau, S.; Deffieux, D.; Pouységu, L. Resveratrol Still Has Something To Say about Aging! Angew. Chem. Int. Ed. 2012, 51, 6824–6826. [Google Scholar] [CrossRef]
  8. Gülçin, I. Antioxidant properties of resveratrol: A structure—Activity insight. Innov. Food Sci. Emerg. Technol. 2010, 11, 210–218. [Google Scholar] [CrossRef]
  9. Vestergaard, M.; Ingmer, H. Antibacterial and antifungal properties of resveratrol. Int. J. Antimicrob. Agents 2019, 53, 716–723. [Google Scholar] [CrossRef]
  10. Lançon, A.; Frazzi, R.; Latruffe, N. Anti-Oxidant, Anti-Inflammatory and Anti-Angiogenic Properties of Resveratrol in Ocular Diseases. Molecules 2016, 21, 304. [Google Scholar] [CrossRef]
  11. Raval, A.P.; Lin, H.W.; Dave, K.R.; DeFazio, R.A.; Morte, D.; Kim, E.J.; Perez-Pinzon, M.A. Resveratrol and Ischemic Preconditioning in the Brain. Curr. Med. Chem. 2008, 15, 1545–1551. [Google Scholar] [CrossRef]
  12. Cho, S.; Namkoong, K.; Shin, M.; Park, J.; Yang, E.; Ihm, J.; Thu, V.T.; Kim, H.K.; Han, J. Cardiovascular Protective Effects and Clinical Applications of Resveratrol. J. Med. Food 2017, 20, 323–334. [Google Scholar] [CrossRef]
  13. Yang, X.; Xu, S.; Qian, Y.; Xiao, Q. Resveratrol regulates microglia M1/M2 polarization via PGC-1α in conditions of neuroinflammatory injury. Brain Behav. Immun. 2017, 64, 162–172. [Google Scholar] [CrossRef]
  14. Moussa, C.; Hebron, M.; Huang, X.; Ahn, J.; Rissman, R.A.; Aisen, P.S.; Turner, R.S. Resveratrol regulates neuro-inflammation and induces adaptive immunity in Alzheimer’s disease. J. Neuroinflamm. 2017, 14, 1–10. [Google Scholar] [CrossRef] [Green Version]
  15. Li, Y.-R.; Li, S.; Lin, C.-C. Effect of resveratrol and pterostilbene on aging and longevity. BioFactors 2018, 44, 69–82. [Google Scholar] [CrossRef]
  16. Kapadia, G.J.; Azuine, M.A.; Tokuda, H.; Takasaki, M.; Mukainaka, T.; Konoshima, T.; Nishino, H. Chemopreventive effect of resveratrol, sesamol, sesame oil and sunflower oil in the Epstein-Barr virus early antigen activation assay and the mouse skin two-stage carcinogenesis. Pharmacol. Res. 2002, 45, 499–505. [Google Scholar] [CrossRef]
  17. Szkudelska, K.; Nogowski, L.; Szkudelski, T. Resveratrol, a naturally occurring diphenolic compound, affects lipogenesis, lipolysis and the antilipolytic action of insulin in isolated rat adipocytes. J. Steroid Biochem. Mol. Biol. 2009, 113, 17–24. [Google Scholar] [CrossRef]
  18. Dermani, F.K.; Saidijam, M.; Amini, R.; Mahdavinezhad, A.; Heydari, K.; Najafi, R. Resveratrol Inhibits Proliferation, Invasion, and Epithelial-Mesenchymal Transition by Increasing miR-200c Expression in HCT-116 Colorectal Cancer Cells. J. Cell. Biochem. 2017, 118, 1547–1555. [Google Scholar] [CrossRef]
  19. Porcu, M.; Chiarugi, A. The emerging therapeutic potential of sirtuin-interacting drugs: From cell death to lifespan extension. Trends Pharmacol. Sci. 2005, 26, 94–103. [Google Scholar] [CrossRef]
  20. Shakibaei, M.; Harikumar, K.B.; Aggarwal, B.B. Resveratrol addiction: To die or not to die. Mol. Nutr. Food Res. 2009, 53, 115–128. [Google Scholar] [CrossRef]
  21. Baur, J.A.; Sinclair, D.A. Therapeutic potential of resveratrol: The in vivo evidence. Nat. Rev. Drug Discov. 2006, 5, 493–506. [Google Scholar] [CrossRef] [PubMed]
  22. Walle, T. Bioavailability of resveratrol. Ann. N. Y. Acad. Sci. 2011, 1215, 9–15. [Google Scholar] [CrossRef]
  23. Shimoda, K.; Kubota, N.; Uesugi, D.; Hamada, H.; Tanigawa, M.; Hamada, H. Synthesis and pharmacological evaluation of glycosides of resveratrol, pterostilbene, and piceatannol. Ann. N. Y. Acad. Sci. 2015, 1348, 141–149. [Google Scholar] [CrossRef]
  24. Biasutto, L.; Marotta, E.; Bradaschia, A.; Fallica, M.; Mattarei, A.; Garbisa, S.; Zoratti, M.; Paradisi, C. Soluble polyphenols: Synthesis and bioavailability of 3,4′,5-tri(α-d-glucose-3-O-succinyl) resveratrol. Bioorganic Med. Chem. Lett. 2009, 19, 6721–6724. [Google Scholar] [CrossRef]
  25. Regev-Shoshani, G.; Shoseyov, O.; Bilkis, I.; Kerem, Z. Glycosylation of resveratrol protects it from enzymic oxidation. Biochem. J. 2003, 374, 157–163. [Google Scholar] [CrossRef] [Green Version]
  26. Dembitsky, V.M. Astonishing diversity of natural surfactants: 5. Biologically active glycosides of aromatic metabolites. Lipids 2005, 40, 869–900. [Google Scholar] [CrossRef]
  27. Torres, P.; Poveda, A.; Jimenez-Barbero, J.; Parra, J.L.; Comelles, F.; Ballesteros, A.O.; Plou, F.J. Enzymatic Synthesis of α-Glucosides of Resveratrol with Surfactant Activity. Adv. Synth. Catal. 2011, 353, 1077–1086. [Google Scholar] [CrossRef]
  28. Cichewicz, R.H.; Kouzi, S.A. Biotransformation of Resveratrol to Piceid byBacillus cereus. J. Nat. Prod. 1998, 61, 1313–1314. [Google Scholar] [CrossRef]
  29. Holland, H.L.; Morris, T.A.; Nava, P.J.; Zabic, M. A new paradigm for biohydroxylation by Beauveria bassiana ATCC 7159. Tetrahedron 1999, 55, 7441–7460. [Google Scholar] [CrossRef]
  30. Zhan, J.; Gunatilaka, A.A.L. Selective 4′-O-methylglycosylation of the pentahydroxy-flavonoid quercetin byBeauveria bassianaATCC 7159. Biocatal. Biotransform. 2006, 24, 396–399. [Google Scholar] [CrossRef]
  31. Ha, S.K.; Kang, M.C.; Lee, S.; Darlami, O.; Shin, D.; Choi, I.; Kim, K.H.; Kim, S.Y. Generation of Stilbene Glycoside with Promising Cell Rejuvenation Activity through Biotransformation by the Entomopathogenic Fungus Beauveria Bassiana. Biomedicines 2021, 9, 555. [Google Scholar] [CrossRef]
  32. Wang, L.-X.; Heredia, A.; Song, H.; Zhang, Z.; Yu, B.; Davis, C.; Redfield, R. Resveratrol glucuronides as the metabolites of resveratrol in humans: Characterization, synthesis, and anti-HIV activity. J. Pharm. Sci. 2004, 93, 2448–2457. [Google Scholar] [CrossRef]
  33. Learmonth, D.A. A Concise Synthesis of the 3-O-β-D- and 4‘-O-β-D-Glucuronide Conjugates of trans-Resveratrol. Bioconjugate Chem. 2003, 14, 262–267. [Google Scholar] [CrossRef]
  34. Botella, L.; Nájera, C. Synthesis of methylated resveratrol and analogues by Heck reactions in organic and aqueous solvents. Tetrahedron 2004, 60, 5563–5570. [Google Scholar] [CrossRef]
  35. DeNinno, M.P.; Etienne, J.B.; Duplantier, K.C. A method for the selective reduction of carbohydrate 4,6-O-benzylidene acetals. Tetrahedron Lett. 1995, 36, 669–672. [Google Scholar] [CrossRef]
  36. Montero, J.-L.; Winum, J.-Y.; Leydet, A.; Kamal, M.; Pavia, A.A.; Roque, J.-P. A convenient synthesis of peracetylated glycosyl halides using bismuth(III) halides as catalysts. Carbohydr. Res. 1997, 297, 175–180. [Google Scholar] [CrossRef]
  37. Hongu, M.; Saito, K.; Tsujihara, K. Solid-Liquid Phase Transfer Catalyzed Novel Glycosylation Reaction of Phenols. Synth. Commun. 1999, 29, 2775–2781. [Google Scholar] [CrossRef]
Figure 1. Chemical structures of resveratrol 1, resvebassianol A (2), and 3-O-β-(4‴-O-methylglucopyranosyl) resveratrol 3.
Figure 1. Chemical structures of resveratrol 1, resvebassianol A (2), and 3-O-β-(4‴-O-methylglucopyranosyl) resveratrol 3.
Antioxidants 10 01509 g001
Scheme 1. Retrosynthetic analysis of 4′-O-β- (4‴-O-methylglucopyranosyl)resveratrol 2.
Scheme 1. Retrosynthetic analysis of 4′-O-β- (4‴-O-methylglucopyranosyl)resveratrol 2.
Antioxidants 10 01509 sch001
Scheme 2. Retrosynthetic analysis of 3-O-β-(4‴-O-methylglucopyranosyl)resveratrol 3.
Scheme 2. Retrosynthetic analysis of 3-O-β-(4‴-O-methylglucopyranosyl)resveratrol 3.
Antioxidants 10 01509 sch002
Scheme 3. Synthesis of 4-O-methylglucopyransyl bromide 6.
Scheme 3. Synthesis of 4-O-methylglucopyransyl bromide 6.
Antioxidants 10 01509 sch003
Scheme 4. Synthesis of diacetoxystyrene 5 and dihydroxystyrene 12.
Scheme 4. Synthesis of diacetoxystyrene 5 and dihydroxystyrene 12.
Antioxidants 10 01509 sch004
Scheme 5. Synthesis of 4′-O-β-(4‴-O-methylglucopyranosyl)resveratrol (2).
Scheme 5. Synthesis of 4′-O-β-(4‴-O-methylglucopyranosyl)resveratrol (2).
Antioxidants 10 01509 sch005
Scheme 6. Synthesis of 3-O-β-(4‴-O-methylglucopyranosyl)resveratrol (3).
Scheme 6. Synthesis of 3-O-β-(4‴-O-methylglucopyranosyl)resveratrol (3).
Antioxidants 10 01509 sch006
Table 1. Optimization of glycosylation reaction for synthesis of 4 a.
Table 1. Optimization of glycosylation reaction for synthesis of 4 a.
Antioxidants 10 01509 i001
Entry aBaseReagentSolventTemp. (°C)Yield (%) d
1 Ag2CO3 (1eq)CH3CNr.t16
2 bNaOHTBABCHCl3:H2O (1:1)4514
3 bK2CO3TBABCHCl3:H2O (1:1)4517
4 cK2CO3BnNBu3ClCHCl3r.t57
a Reaction was carried out using 1 equiv of both starting materials 7 and 6. b Base (1.1 eq), TBAB (0.2 eq), c Base (2.5 eq), and BnNBu3Cl (0.1 eq). d Isolated yield.
Table 2. Optimization of glycosylation reaction for synthesis of 10 a.
Table 2. Optimization of glycosylation reaction for synthesis of 10 a.
Antioxidants 10 01509 i002
EntryBaseReagentSolventTemp. (°C)Yield (%) d
1 Ag2CO3CH3CNr.t19
2 bNaOHTBABCHCl3:H2O (1:1)4513
3 bK2CO3TBABCHCl3:H2O (1:1)4515
4 cK2CO3BnNBu3ClCHCl3r.t40
a Reaction was carried out using 1 equiv of both starting materials 6 and 12. b Base (1.1 eq), TBAB (0.2 eq), c Base (2.5 eq), and BnNBu3Cl (0.1 eq). d Isolated yield.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Darlami, O.; Shin, D. Total Synthesis of Resvebassianol A, a Metabolite of Resveratrol by Beauveria bassiana. Antioxidants 2021, 10, 1509. https://doi.org/10.3390/antiox10101509

AMA Style

Darlami O, Shin D. Total Synthesis of Resvebassianol A, a Metabolite of Resveratrol by Beauveria bassiana. Antioxidants. 2021; 10(10):1509. https://doi.org/10.3390/antiox10101509

Chicago/Turabian Style

Darlami, Om, and Dongyun Shin. 2021. "Total Synthesis of Resvebassianol A, a Metabolite of Resveratrol by Beauveria bassiana" Antioxidants 10, no. 10: 1509. https://doi.org/10.3390/antiox10101509

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop