Antimicrobial activity of Memecylon malabaricum leaves

Isolation, identification and in vitro biological evaluation of phytochemicals from Memecylon randerianum: a medicinal plant endemic to Western Ghats of India

The present investigation reports evaluation of phytochemical content, antimicrobial, antioxidant, antidiabetic and anticancer properties of the methanolic crude extracts prepared from Memecylon randerianum leaves. Qualitative evaluation showed the presence of carbohydrates, reducing sugars, alkaloids, phenols, flavonoids, cardiac glycosides, steroids, phytosterols, terpenoids, diterpenoids and coumarins. Quantitative estimation for phenols, flavonoids and alkaloids indicated total phenolic content 11.95 mg GAE/g, total flavonoid content 20.34 mg QE/g and total alkaloid content 316.68 mg AE/g dry weight of the crude extract respectively. The methanolic extract demonstrated effective antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans. The preparation also demonstrated good antioxidant and antidiabetic activities. Anticancer activity was evaluated against breast (MCF), oral (KB) and lung (A-549) cancer cell lines and the respective IC₅₀ values were found to be 159.81 ± 7.54 µg/mL, 240.21 ± 2.57 µg/mL and 124.17 ± 2.10 µg/mL which are comparable to IC₅₀ values of Paclitaxel.

Polyanthumin, a novel cyclobutane chalcone trimmer from Memecylon polyanthum

A novel unusual trimmer chalcone, polyanthumin (1), together with five known compounds myricetin 3-O-(3″-O-galloyl)-α-l-rhamnopyranoside (2), sulfuretin (3), fustin (4), gallic acid (5), and ethyl gallate (6), was isolated from the dry stems of Memecylon polyanthum H.L. Li. Among them, compound 1 is a new chalcone trimmer with a novel cyclobutane skeleton in nature. Compounds 3 and 4 are flavonoids carrying a single 7-OH in A ring, which provided the first example of these class flavonoids from the family Melastomataceae. In addition, the antitumor activities for 2-4 were reported for the first time in this study. The antitumor effects of the isolated compounds 1-6 in vitro were assayed by the SRB method using human cancer K562 cells, with the inhibition rates ranging from 39.4% to 54.5% at 100 μg/ml. The IC50 values of compounds 1 and 3 for the inhibition of K562 cell proliferation were determined to be 45.4 and 30.5 μg/ml, respectively. To the best of our knowledge, compound 1 was the second sample as chalcone trimer. In addition, the antitumor activities for 2-4 were reported for the first time in this study.