Antioxidant and Antibacterial Natural Products Evaluation from Terrestrial Streptomyces Species Strain KAV 2 Isolated from Rhizosphere Regions of Piper betle

Abstract

Terrestrial actinomycetes have come to antimicrobial production dominantly and have been the focussed area for bioprospecting of novel secondary metabolites. The secondary metabolites of the fermented culture were prepared by solvent extraction method. In the current research work, Streptomyces species were completely analysed for antioxidant and antibacterial activities and also the GCMS analysis of the crude active extract revealed the presence of 12 bioactive compounds, which makes the particular strain as a potent source for drug validation research. The antioxidant activities assessed by four different methods proved that the crude extract could be effective against various kinds of free radicals. The maximum free radical scavenging activity for Ethyl acetate fraction by DPPH method was found to be 94.84±0.24% at 60 µg/mL concentration and the IC₅₀ value was 26.91 µg/mL concentration respectively. The maximum ferric reducing ability for Ethyl acetate fraction was found to be 81.83±0.48% at 120 µg/mL concentration and the RC₅₀ value was 53.16 µg/mL concentration respectively. The qualitative screening for active compounds gave positive results for alkaloids, phenols, tannins, terpenoids, steroids. The Streptomyces species demonstrated antibacterial activities with maximum zone of inhibition as 19 mm against tested bacterial pathogens such as Micrococcus luteus and Bacillus subtilis.

Keywords: Streptomyces, DPPH˙ radical, ABTS^●+ radical cation, antibacterial, GCMS