Abstract
Strain VE2 was isolated from the stem tissue of Vernonia cinerea (L.) Less. and identified as Streptomyces sp. on the basis of morphology, chemotaxonomy and 16SrDNA sequencing. The fractionation of the crude ethyl acetate (CEA) extract from VE2 cultures led to the isolation of two acetogenins; squamocin and rollidecin B; these compounds and CEA extract had potential in antibacterial and antioxidant activities. The crude extract showed the highest activity against Salmonella Typhi ATCC19430 and Bacillus cereus ATCC7064, with MIC values of 32 µg/ml. Squamocin also showed the lowest MIC (32 µg/ml) and Minimum Bactericidal Concentration (MBC) (128 µg/ml) against S. Typhi and B. cereus with corresponding large diameter of the zone of inhibitions (27.5 and 28.2 mm, respectively). Rollidecin B showed the highest DPPH antioxidant activity with SC50 value of 58.92 µg/ml.
Highlights
Endophytes are microorganisms that colonize inside plant tissue
The fractionation of the crude ethyl acetate (CEA) extract from VE2 cultures led to the isolation of two acetogenins; squamocin and rollidecin B; these compounds and CEA extract had potential in antibacterial and antioxidant activities
We report here the isolation of the stems of Vernonia cinerea (L.) Less. of another endophytic Streptomyces sp
Summary
Endophytes are microorganisms that colonize inside plant tissue. They live between the living cells of their respective host and cause no overt tissue damage (Azevedo et al, 2001; Zhang et al, 2006; Bandara et al, 2006). They would help to improve the host plant's growth and promotional activity against diseases caused by phytopathogenic fungi (Azevedo et al, 2001). Many endophytic Streptomyces were isolated from plant tissues, some of them produced the secondary metabolites against bacteria and phytopathogenic fungi (Taechowisan et al, 2005, 2008, 2012, 2014)
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