The secondary metabolites and antioxidant potential of selected terrestrial isolates of actinomycetes / Nur Zaizah Afiqah Hajin

The purpose of this study is to isolate, detect secondary metabolites and to determine the antioxidant potential of selected terrestrial isolates of actinomycetes. The four antagonistic actinomycetes N1 , N2, N3 and N4 were isolated and identified as a genus Streptomyces based on the primary screening of antibacterial potential, gram staining, KOH staining, morphological observation and colony morphology observation. The supernatants of crude extracts were extracted using ethyl acetate solvents and secondary metabolites screening for six compounds such as alkaloids, flavonoids, phenols, saponins, tannins and terpenoids were performed using the ethyl acetate crude extracts and all of the crude extracts showed a presence of different compounds of secondary metabolites. The crude extracts were then further investigated for its antioxidant activity using 1,1 -diphenyl, 2 picryl hydrazyl (DPPH) radical scavenging activity. Based on the DPPH scavenging activity results it revealed that all crude extracts from strains N1, N2, N3 and N4 showed a significant potential of antioxidant properties. Besides that, the activity of the crude extracts with the highest inhibition percentage of 80.58% was belonged to N2 isolate. Therefore, the information from this current study can help to provide valuable insight of the terrestrial actinomycetes and also provide inventory data for further identification of potent compounds which might be developed as good antioxidant agent in the future.