Chemical constituents and antibacterial properties of Indocalamus latifolius McClure leaves, the packaging material for "Zongzi"

Abstract

The glutinous rice dumpling named "Zongzi" in Chinese is a type of traditional food that is popular in East Asian countries. "Zongzi" is made of glutinous rice and wrapped in the leaves of Indocalamus latifolius McClure as the packaging material. Four new compounds, latifoliusine A (2), (7S,8R) syringylglycerol-8-O-4′-sinapyl ether 4-O-β-D-glucopyranoside (7), (7S,8S) syringylglycerol-8-O-4′-sinapyl ether 7-O-β-D-glucopyranoside (8), and (7R,8S) syringylglycerol-8-O-4′-sinapyl ether 7-O-β-D-glucopyranoside (10), along with six known compounds (1, 3-6 and 9) were isolated from I. latifolius McClure leaves. The structures and relative configurations of the compounds were determined by detailed spectroscopic analysis, high-resolution electrospray ionization mass spectroscopy (HRESIMS), heteronuclear single quantum correlation (HSQC), heteronuclear multiple bond correlation (HMBC), nuclear overhauser enhancement (NOE) and circular dichroism (CD). All of the isolated compounds were screened for their antibacterial activities in vitro. The results indicated that apigenin 6-C-α-Larabinopyranosyl- 8-C-β-D-glucopyranoside (5) and apigenin 7-O,8-C-di-glucopyranoside (6) have antibacterial activities against four bacterial strains (Staphylococcus aureus, Bacillus thuringiensis, Escherichia coli and Pseudomonas solanacearum).