Elsevier

Bioorganic Chemistry

Volume 82, February 2019, Pages 26-32
Bioorganic Chemistry

Short communication
Bioactivity-based analysis and chemical characterization of anti-inflammatory compounds from Curcuma zedoaria rhizomes using LPS-stimulated RAW264.7 cells

https://doi.org/10.1016/j.bioorg.2018.09.027Get rights and content

Highlights

Abstract

Inflammation is not only a self-defense response of the innate immune system, but also the pathogenesis mechanism of multiple diseases such as arthritis, neurodegeneration, and cancer. Curcuma zedoaria Roscoe (Zingiberaceae), an indigenous plant of India, has been used traditionally in Ayurveda and folk medicine. As part of our ongoing efforts to screen traditional medicinal plants exhibiting pharmacological potential and to characterize the compounds involved, we examined the anti-inflammatory effects of the MeOH extract of C. zedoaria rhizomes using lipopolysaccharide (LPS)-stimulated RAW264.7 murine macrophage cells and found that MeOH extract inhibited the synthesis of nitric oxide (NO) in a dose-dependent manner (IC50: 23.44 ± 0.77 μg/mL). In our efforts to characterize the compounds responsible for these anti-inflammatory effects, bioactivity-guided fractionation of the MeOH extract and chemical investigation of its active hexane-soluble fraction led to the successful isolation of five sesquiterpenes (15), the structures of which were elucidated by NMR spectroscopic analysis and LC/MS analysis. Among them, curcuzedoalide (5) exhibited potent inhibitory effects on NO synthesis (IC50: 12.21 ± 1.67 μM) and also suppressed pre-inflammatory protein expression of iNOS and COX-2. Curcuzedoalide (5) was thus determined to be a contributor to the anti-inflammatory effect of C. zedoaria rhizomes and could be a potential candidate for therapeutic applications.

Introduction

Acute inflammation is a well-known self-defense response of the innate immune system to protect the body from injuries or pathogens. However, any disorder in the regulation of the acute inflammation process can lead to chronic inflammation, which is associated with carcinogenesis [1]. Up to this point, many pathological studies showed that the inflammatory pathway plays a leading role in the pathogenesis mechanisms of cancer [2] and several other diseases such as arthritis, atherosclerosis, Alzheimer’s disease, and depression [3], [4], [5]. Screening for anti-inflammatory agents is the first step in many studies, which can also target new chemopreventive candidates.

Curcuma zedoaria Roscoe (Zingiberaceae), also known as white turmeric or zedoaria, is a perennial herbaceous plant that has been used in Ayurveda for the treatment of menstrual disorders, indigestion, nausea, and carcinomas [6]. The C. zedoaria rhizome is commonly called “Ezhu” in Chinese, and has been used in traditional Chinese medicine to treat various cancers [7]. Previous studies reported that the extracts of this plant demonstrated various pharmacological effects including antimicrobial, anti-cancer, anti-allergen, and analgesic effects [6], [8], [9], [10]. C. zedoaria is a rich natural source of sesquiterpenes, which have exhibited a number of biological activities such as anti-inflammatory [11], antibabesial [12], cytotoxic [9], and anti-fungal properties [13].

In this study, as part of our ongoing efforts to screen traditional medicinal plants exhibiting pharmacological potential and to characterize the responsible compounds [14], [15], [16], [17], [18], [19], [20], we found that the MeOH extract of C. zedoaria rhizomes exerted a cytotoxic effect on AGS cells [21]. Based on the bioactivity-guided fractionation and chemical investigation of the MeOH extract, cytotoxic sesquiterpenes, which contribute to the cytotoxicity of C. zedoaria, were identified and the underlying molecular mechanisms for their cytotoxic effect were explored [21]. In this study, in hoping to discover other bioactivities of the C. zedoaria rhizome, we examined the anti-inflammatory effects of the MeOH extract of C. zedoaria rhizomes using lipopolysaccharide (LPS)-stimulated RAW264.7 murine macrophage cells and found that the MeOH extract inhibited the synthesis of nitric oxide (NO) in a dose-dependent manner. In our efforts to characterize the compounds from the MeOH extract responsible for these anti-inflammatory effects, bioactivity-guided fractionation and chemical investigation of the MeOH extract were performed, which led to the successful isolation of five sesquiterpenes (15). Here, we report the anti-inflammatory effects of C. zedoaria rhizomes, the identity of the isolated constituents responsible for the anti-inflammatory effects, and the bioactivity of the isolates with regards to the molecular basis underlying anti-inflammatory activity.

Section snippets

General experimental procedures

Optical rotations were measured using a Jasco P-1020 polarimeter (Jasco, Easton, MD, USA). IR and UV spectra were acquired with a Bruker IFS-66/S FT-IR spectrometer (Bruker, Karlsruhe, Germany) and Agilent 8453 UV–Vis spectrophotometer (Agilent Technologies, Santa Clara, CA, USA), respectively. LC/MS analysis was performed using an Agilent 1200 HPLC with a photodiode array detector system and an analytical Kinetex C18 100 Å column (100 mm × 2.1 mm i.d., 5 μm) (Phenomenex, Torrance, CA) coupled

Anti-inflammatory effects of MeOH extract of C. Zedoaria rhizomes

The dried rhizomes of C. zedoaria were extracted with MeOH at 65 °C and filtered. The filtrate was evaporated under reduced pressure with a rotavapor to obtain a crude MeOH extract, which was examined for anti-inflammatory properties using LPS-stimulated RAW264.7 murine macrophage cells. As shown in Fig. 1, a cell viability assay was conducted to check on the cytotoxic effects of the test samples. The MeOH extract of the C. zedoaria rhizomes exhibited cytotoxicity from the concentration of

Conclusions

In the current study, we found that the MeOH extract of C. zedoaria rhizomes inhibited NO production in LPS-activated RAW264.7 macrophages. In our efforts to characterize the compounds responsible for these anti-inflammatory effects, bioactivity-based analysis and chemical investigation of the MeOH extract led to the successful identification of the anti-inflammatory constituent, curcuzedoalide (5), which significantly inhibited NO production in LPS-activated RAW264.7 macrophages with an IC50

Conflicts of interest

The authors declare no competing financial interest.

Acknowledgements

This work was supported by a National Research Foundation of Korea grant funded by the Korea government (Ministry of Science and ICT) (2018R1A2B2006879). This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2012R1A5A2A28671860, 2017R1C1B5015841).

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    These two authors contributed equally to the work described in this study.

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