New ent-kaurene and germacrene derivatives from Mesona procumbens Hemseley and their biological activity

Abstract

Mesona procumbens Hemseley is a well-known traditional herbal medicine used for heat-related ailments. In Taiwan, boiled extracts of M. procumbens are also used as desserts called grass jelly. In this study, the hexane extract from 75% EtOH of M. procumbens showed potent activities on inhibition of E. coli β-glucuronidase (eβG) and NO production and cytotoxicity against MCF-7 and HepG2 cancer cell lines. Furthermore, using various flash columns and HPLC chromatography on the bioactive layer led to the isolation of twelve compounds (1–12), including a new ent-kaurene, mesokaurol A (1), and a new germacrene derivative, mesogermapene A (2). Their structures were elucidated by extensive spectroscopic analyses, especially 2 D NMR and mass data. Biological assays showed that compound 9 (linolenic acid) had specific activity on inhibition of eβG (68.27%) at 100 µg/mL but was non-inhibitory to human β-glucuronidase. Compound 1 possessed significant cytotoxicity against MCF-7 (EC₅₀ = 9.76 µM) and HepG2 (EC₅₀ = 8.64 µM) cancer cell lines.

Graphical Abstract

Keywords:

• Anti-β-glucuronidase
• cytotoxicity
• germacrene
• Kaurane-type diterpene
• Mesona procumbens Hemseley

Supplementary material

NMR spectra of compounds 1 and 2 and bioassay methods including anti-β-glucuronidase (eβG), anti-NO production and cytotoxicity are available as supplementory data.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by grants from Ministry of Science and Technology (MOST 104-2320-B-077-006-MY3 and MOST 107-2320-B-077-003-MY3, 108-2811-B-077-500) and National Research Institute of Chinese Medicine, Ministry of Health and welfare (MOHW110-NRICM-B-315-000002).