Four cucurbitane glycosides taimordisins A-D with novel furopyranone skeletons isolated from the fruits of Momordica charantia

Chia-Ching Liaw; I-Wen Lo; Yu-Chi Lin; Hung-Tse Huang; Li-Jie Zhang; Pin-Chun Hsiao; Tsung-Lin Li; Yao-Haur Kuo

doi:10.1016/j.fochx.2022.100286

Four cucurbitane glycosides taimordisins A-D with novel furopyranone skeletons isolated from the fruits of Momordica charantia

Food Chem X. 2022 Mar 16:14:100286. doi: 10.1016/j.fochx.2022.100286. eCollection 2022 Jun 30.

Authors

Chia-Ching Liaw^{1

2}, I-Wen Lo³, Yu-Chi Lin¹, Hung-Tse Huang¹, Li-Jie Zhang¹, Pin-Chun Hsiao¹, Tsung-Lin Li³, Yao-Haur Kuo^{1

4

5}

Affiliations

¹ Division of Chinese Material Medica Development, National Research Institute of Chinese Medicine, Taipei 112026, Taiwan.
² Department of Biochemical Science and Technology, National Chiayi University, Chiayi 600355, Taiwan.
³ Genomics Research Center, Academia Sinica, Taipei 115201, Taiwan.
⁴ Graduate Institute of Integrated Medicine, College of Chinese Medicine, China Medical University, Taichung 404333, Taiwan.
⁵ Taoyuan 327008, Taiwan.

Abstract

Four novel triterpene glycosides, taimordisins A-D (1-4), were discovered from fresh fruits of Taiwanese Momordica charantia. The chemical framework and relative stereochemistry of these four natural products were isolated, purified, and determined by using various separation and spectroscopy techniques. Each of them features a unique bicyclic-fused or trifuso-centro-fused ring system. Notably, 1 and 2 are cucurbitane-based compounds possessing a new C-24 and C-2″ carbon-carbon linkage with 5-hydroxy-2-(hydroxymethyl)tetrahydro-4H-pyran-4-one and 6-(hydroxymethyl)tetrahydro-4H-pyran-3,4,4-triol units, respectively, and represented an unprecedented molecular skeleton. In terms of biosynthesis, they all originate from a common precursor 3-hydroxycucurbita-5,24-dien-19-al-7,23-di-O-β-glucopyranoside. Of two sugar moieties, the one at 23-O-β-glucopyranoside grants each individual congener uniqueness likely through microbial symbiont-mediated intramolecular transformation into two major types of furo[2,3-b]pyranone and furo[3,2-c]pyranone derivatives. These new products possess desirable anti-inflammatory biological activities in addition to being generally regarded as safe.

Keywords: Anti-inflammatory; Cucurbitane; Momordica charantia; NO production; Taimordisins.