Trans-resveratrol, piceatannol and gallic acid: Potent polyphenols isolated from Mezoneuron benthamianum effective as anticaries, antioxidant and cytotoxic agents

Abstract

Phytochemical investigation of the ethyl acetate extract of the root of Mezoneuron benthamianum, a shrub commonly used as chewing stick in the southwest of Nigeria, led to the isolation of three compounds characterised as trans-resveratrol, piceatannol and gallic acid by the use of spectroscopic techniques. The anticaries activity of the polyphenols was evaluated against four oral bacteria pathogens (Streptococcus mutans, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli), isolated from clinical samples presented by patients having dental caries, while their antioxidant and cytotoxic activities were determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and brine shrimp (artemia salina nauplii) bioassay techniques. The results showed that the isolated compounds exhibited very strong anticaries activity with minimum inhibitory concentration (MIC) ranging from 25 to 300 µg/ml, antioxidant activity with IC50 of 35.81, 30.35 and 11.73 µg/ml, when compared with ascorbic acid (IC50 = 38.20 µg/ml) and cytotoxic activity with LC50 of 7.15, 99.99 and 98.71 µg/ml for resveratrol, piceatannol and gallic acid respectively The isolated compounds demonstrated very strong anticaries, antioxidant and cytotoxic activities. This study further justifies the ethno-medicinal use of M. benthamianum as an effective tool in maintaining oral hygiene. Keywords: Mezoneuron benthamianum, Polyphenols, Dental caries, Resveratrol, Piceatannol