Indole alkaloids from the aerial parts of Kopsia fruticosa and their cytotoxic, antimicrobial and antifungal activities

Abstract

A chemical investigation on the 80% EtOH extract of the aerial parts of Kopsia fruticosa led to five new indole alkaloids, kopsifolines G-K (1–5), and one known alkaloid, kopsifoline A (6). Structural elucidation of all the compounds were performed by spectral methods such as 1D and 2D (1H-1H COSY, HMQC, and HMBC) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated components were evaluated in vitro for cytotoxic activities against seven tumor cell lines, antimicrobial activities against two Gram-positive bacteria and five Gram-negative bacteria, and antifungal activities against five pathogens. As a result, alkaloids 3–5 exhibited some cytotoxicity against all of seven tested tumor cell lines (HS-1, HS-4, SCL-1, A431, BGC-823, MCF-7, and W480) with IC50 values of 11.8–13.8, 10.3–12.5, and 7.3–9.5 μM, respectively. Alkaloids 3–5 also possessed significant antimicrobial and antifungal activities which was reported for the first time for the alkaloids isolated from Kopsia genus.