iStreptomyces zerumbet/i, a Novel Species from iZingiber zerumbet/i (L.) Smith and Isolation of Its Bioactive Compounds

Streptomyces zerumbet W14, a novel species of the endophyte genus Streptomyces was isolated from the rhizome tissue of Zingiber zerumbet (L.) Smith. Identification of strain W14 was based on its morphology, chemotaxonomy and phylogenetic analysis using 16S rDNA sequence. It was classified as the secondary meabolites of the culture extract were studied. The major active ingredients from the crude extract were purified by silica gel column chromatography and identified by spectroscopic data. The crude extract and purified compounds were tested for their biological activities on antibacterial and anti-inflammatory properties. The crude extract showed inhibition on the growth of Gram-positive bacteria with the MIC and MBC values of 8 - 32 μg/ml and 32 - 128 μg/ml, respectively. The isolated compounds were identified to be methyl 5-(hydroxymethyl)furan-2-carboxylate (1) and geldanamycin (2). Bioassay studies showed that compound 1 had antibacterial activity against Staphylococus aureus ATCC 25923 and Methicillin Resistant S. aureus strain Sp6 (clinical isolate) with the MIC and MBC values of 1 μg/ml and 16 - 64 μg/ml, respectively, and also showed activity against Bacillus Calmette-Guérin (vaccine strain) with MIC and MBC values of 128.00 μg/ml and 128.00 μg/ml, respectively. The compound 2 at the concentration of 1 - 5 μg/ml had in vitro anti-inflammatory activity on LPS-induced RAW 264.7 cells by inhibition of mRNA expression and production of inducible NO synthase (iNOS), tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). These results suggest that compounds 1 and 2 produced by S. zerumbet W14 (an endophyte of Z. Zerumbet) have antibacterial and anti-inflammatory activities, respectively. Therefore, the future studies on these compounds could be useful for the management of bacterial infections and inflammatory diseases.