Inhibition of Secretory Aspartyl Protease of Candida albicans by metabolites of Streptomyces chrestomyceticus strain ADP4

Candida albicans is a commensal but a significant opportunistic pathogen. Various pathogenic attributes and virulence factors are found to be responsible for devastating Candida infections. Secretory aspartic proteases (Saps) enable hyphae formation, adhesion and phenotypic switching; digestion of the host cell membranes and evading host immune response by degrading and inactivating the central human complement components. Therefore, an agent capable of inhibiting production of C. albicans Saps will be useful in the treatment of such infections. The partially purified fractions of Streptomyces chrestomyceticus strain ADP4 displayed strong anti-Candida activity, hence were investigated further for their ability to inhibit production of Saps. Strong inhibition of production of Saps was observed when tested against the ATCC strain of C. albicans. Docking studies of the GCMS-predicted molecules of the metabolite extract and of the various fractions with a Sap of C. albicans were performed using VLife MDS4.6. These studies revealed the significant affinity of GCMS-predicted molecules when compared with the standard Sap inhibitor, Pepstatin A.