Antimicrobial and Radical Scavenging Activity of Memecylon malabaricumMemecylon talboltianum Brandis

Abstract

The present study was conducted to determine antimicrobial and radical scavenging potential of extract of two species of the genus Memecylon (Melastomataceae) viz., M. malabaricum (C.B. Clarke) Cogn. and M. talboltianum Brandis. The shade dried leaf materials of both Memecylon species were extracted using methanol. Antibacterial activity of leaf extracts was evaluated against five drug resistant uropathogenic bacteria by Agar well diffusion assay. Antifungal activity of leaf extracts was tested on the basis of mycelial growth inhibition of Colletotrichum capsici (isolated from anthracnose of chilli). Radical scavenging activity of extracts was determined by performing DPPH free radical scavenging activity. Total phenolic content of extracts was estimated by Folin-Ciocalteau reagent method. The extracts were subjected to preliminary phytochemical analysis to detect the presence of phytoconstituents. Among extracts, extract of M. malabaricum inhibited all test bacteria and inhibitory potential was marked against Gram positive bacteria than Gram negative bacteria. C. capsici was highly susceptible to extract of M. malabaricum when compared to extract of M. talboltianum. Overall, extract of M. malabaricum displayed marked antimicrobial activity than extract of M. talboltianum. Extract of M. malabaricum scavenged DPPH radicals more efficiently (IC50 6.26μg/ml) when compared to extract of M. talboltianum (IC50 43.80μg/ml). The content of total phenolics was also high in leaf extract of M. malabaricum (112μg GAE/mg) than that of M. talboltianum (28μg GAE/mg). Preliminary phytochemical analysis of leaf extracts revealed the presence of flavonoids, tannins, saponins and glycosides in both extracts. The antimicrobial and radical scavenging activity of leaf extracts could be ascribed to the presence of phytochemicals mainly phenolic compounds. These plants appear to be potential candidates for control of anthracnose disease of chilli and for development of agents active against drug resistant uropathogens and oxidative damage.

Keywords: Memecylon; Antimicrobial; Agar well diffusion; Poisoned food technique; Antioxidant; DPPH