Original articleThree minor new compounds from the aerial parts of Leonurus japonicus
Graphical abstract
Phytochemical investigation of the aerial parts of Leonurus japonicus led to the isolation of one new labdane diterpenoid (1) and two new ionone derivatives (2 and 3), together with seven known diterpenoids (4–10). Selected isolates were evaluated their effects on Jurkat IL2 secretion.
Introduction
Leonurus japonicus (Labiatae), commonly called Chinese motherwort, is a herbaceous flowering plant native to several regions in Asia, including China, Korea, Japan and Cambodia. For thousands of years in China, the aerial part of Leonurus japonicus has been primarily used to treat menoxenia, dysmenorrhea, amenorrhea, lochia, oliguresis, ulcerations and other diseases in women, and thus is named “Yi Mu Cao” [1], [2]. Phytochemical investigation on this species has led to discover various natural compounds with different structural patterns, including alkaloids, flavonoids, glycosides, diterpenoids and triterpenoids, among which diterpenoids are the major constituents [3]. Our previous research on the chemical constituents of L. japonicus has led to the isolation of three diterpenoids [4], especially leojaponin A, which is the first example of clerodane-type diterpenoid obtained from L. japonicus. As part of our ongoing program to discover structurally interesting and potential bioactive chemical constituents, we reinvestigated this plant, and obtained three additional new compounds, including one labdane-type diterpenoid, leojaponin D (1), and two ionone derivatives, leojaponones A and B (2 and 3), together with seven known diterpenoids, leojaponins A–C (4–6) [4], leoheteronin D (7) [5], villenol (8) [6], leoheterin (9) [7] and 3α-acetoxy-7β-hydroxy-15-O-methylleopersin C (10) [8] (Fig. 1). Herein, we report the isolation and structure elucidation of the new compounds, as well as the effect on Jurkat IL2 secretion of selected isolates.
Section snippets
Plant material
The aerial parts of L. japonicus were collected in Xichang county, Sichuan Province, China, and identified by Prof. Xi-Wen Li, Kunming Institute of Botany. A voucher specimen (KIB 20120601) was deposited at the State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences.
Extraction and isolation
The air dried aerial parts of L. japonicus (15.0 kg) were extracted with 95% EtOH (3 × 40 L) at room temperature, and the combined solvents were evaporated in
Results and discussion
Compound 1 was obtained as a colorless oil, (c 0.11, MeOH); UV (MeOH) λmax (log ɛ) 203 (4.06) nm. The molecular formula of 1 was assigned as C20H32O2 from its HR-EIMS (m/z 304.2402 [M] +, calcd. 327.2295 [M+Na]+) with five degrees of unsaturation. The IR spectrum revealed the presence of a hydroxyl group (3427 cm−1) and a carboxyl group (1724 cm−1). The 1H NMR spectrum (Table 1) displayed signals of four tertiary methyl groups and one olefinic proton signal (δH 5.17). The 13C NMR
Conclusion
In summary, three new minor compounds, including one labdane-type diterpenoid (1) and two ionone derivatives (2 and 3), together with seven known diterpenoids, were isolated from the aerial parts of L. japonicus. This investigation could shed new light on the further understanding of the chemical constituents of L. japonicus.
Acknowledgments
This project was supported financially by National Natural Science Foundation of China (Nos. 81422046 and 31300293), the National Science and Technology Support Program of China (No. 2013BAI11B02), the Natural Science Foundation of Yunnan Province (No. 2012FB178) and the project sponsored by SRF for ROCS, SEM to W.L. Xiao.
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Leonurus japonicus (Chinese motherwort), an excellent traditional medicine for obstetrical and gynecological diseases: A comprehensive overview
2019, Biomedicine and PharmacotherapyCitation Excerpt :Interestingly, leonuketal (111) possesses an unprecedented tetracyclic skeleton, which comprises a bridged spiroketal moiety fused with a ketal-γ-lactone unit [4]. Compounds 112–114 are halimane diterpenes with a unique cross-conjugated α,β-unsaturated ketone system [22,45], while compound 115 is a clerodane diterpenoid characterized by a 4–O–7 bridge [38]. To date, 36 triterpenoids have been isolated from L. japonicus (Fig. 5), including 11 unusual nortriterpenoids (116–126) that possess a distinctive 19(18→17)-abeo-28-noroleanane-type spirocyclic skeleton with a trans- or cis-acyl substituent at C-3 or C-23 [49,50].
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2018, PhytochemistryCitation Excerpt :Based on the feature of the C-9 side chain, the labdane diterpenoids from this genus can be further classified into the seco-labdane (Fig. 3), the furano-labdane (Fig. 4), the lactone-labdane (Fig. 5) and the spiro-labdane (Fig. 6). The seco-labdane diterpenoids have a linear C-9 side chain, such as leoheteronin D (6) (Giang et al., 2005) and F (7) (Hung et al., 2011), leojaponin A (8), B (9) (Liu et al., 2014b) and D (10), as well as villenol (11) (Zhong et al., 2015) from the aerial parts of L. japonicus (Fig. 3). In addition, norditerpenoids with less carbons on the C-9 side chain were also discovered from the same species.
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These authors contributed equally to this work.