Chiranjeevi Chetapalli, Nagaraju Kumbha, Mary Swapna Mogili, Vijayalakshmi Muvva, Vengateshwaran Thasu Dinakaran
Actinobacteria of mangrove habitats are the potential source of natural products. The work has been undertaken to optimize cultural conditions and elucidate the bioactive compounds produced by a mangrove derived potent rare actinobacterium. Pseudonocardia parietis VLCH-6 was proved as the potent actinobacterium strain, which was derived from the Machilipatnam mangrove habitats of Andhra Pradesh. This identification was based on polyphasic taxonomy, which included morphological, cultural, physiological, biochemical, and molecular approaches. During optimization process, ISP-2 (YMD) broth was recorded as suitable culture medium for enhanced metabolites yield. For maximum yield of the bioactive metabolites, glucose (2%) as carbon source and tryptone (1%) as nitrogen source were noticed. Further, after incubating the strain at 35⁰C for seven days, the optimum yield was observed when it was grown in a modified YMD culture medium that had been amended with NaCl (3%) and K2HPO4 (0.05%) to achieve a pH of 7. High antagonistic activity was demonstrated by the metabolites extracted from the optimized culture broth against a diverse array of pathogens. The isolation of two compounds with potential antimicrobial activity was achieved through column chromatography purification. The structures of bioactive compounds were elucidated through spectroscopic analysis including EIMS, FTIR, 1H NMR and 13C NMR spectra. The two bioactive compounds were characterized as 6-methyl-1,3,8-trihydroxyanthraquinone and 1,8-dihydroxy-3-methylanthracenedione-9,10-dione. These compounds exhibited potential antimicrobial (MIC), anticancer activities against MCF-7 human breast cancer cell line and HEK293 human embryonic kidney cell line. This is the first publication on the characterization of bioactive chemicals produced by Pseudonocardia parietis VLCH-6.