Identification of Nephelium lappaceum leaves phenolic and flavonoid component with radical scavenging, antidiabetic and antibacterial potential

Abstract

<em>Nephelium lappaceum </em>Linn. (Rambutan) is traditionally claimed, as a source of natural antioxidants and for its use in the treatment of diabetes and bacterial infections. The present study investigates the <em>in vitro</em> effect of ethanolic Rambutan leaves extract (NL) for its antioxidant effect, α-glucosidase, α-amylase enzyme inhibition, and antibacterial potentials. The total phenolic, total flavonoid content of NL was quantified and were expressed in terms of gallic acid (19.6±0.04 mg GAE/g) and rutin equivalents (16.7±0.01 mg RUE/g) respectively. The antioxidant assay revealed that NL exhibited significant inhibition of DPPH (IC₅₀±SEM: 1.52±0.03 μg/mL) and ABTS (IC₅₀±SEM: 1.295±0.05 μg/mL) radicals. NL also inhibited both α-amylase (IC₅₀±SEM: 2.624±0.07 μg/mL), α-glucosidase (IC₅₀±SEM: 2.416±0.06 μg/mL) enzyme activities, supported by its antioxidant potential and its phenolic and flavonoid content. The antibacterial activity was screened against seven human pathogenic ATCC strains for which the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were recorded. The selected MIC dose was tested, confirmed by Kirby-Bauer agar well diffusion method. NL exhibited MIC and MBC of 62.5 μg/mL and 125 μg/mL against <em>B.subtilis</em> and <em>E.coli</em> respectively. The results support the scientific claim of NL for its antioxidant, antidiabetic and antibacterial potential.