文摘
The terrestrial actinomycete strain BCC71188 was identified as Streptomyces by its morphology (having spiral chain spore on the aerial mycelium), chemotaxonomy (containing LL-diaminopimelic acid in the cell wall), and 16S rRNA gene sequence analysis [showing high similarity values compared with Streptomyces samsunensis M1463T (99.85 %) and Streptomyces malaysiensis NBRC 16446T (99.40 %)]. The crude extract exhibited antimalarial against Plasmodium falciparum (IC50 0.19 μg/ml), anti-TB against Mycobacterial tuberculosis (MIC 6.25 μg/ml), and antibacterial against Bacillus cereus (MIC 1.56 μg/ml) activities. Therefore, chemical investigation was conducted by employing bioassay-guided method and led to the isolation of 19 compounds including two cyclic peptides (1–2), five macrolides (3–7), new naphthoquinone (8), nahuoic acid C (9), geldanamycin derivatives (10–13), cyclooctatin (14), germicidins A (15) and C (16), actinoramide A (17), abierixin, and 29-O-methylabierixin. These isolated compounds were evaluated for antimicrobial activity, such as antimalarial, anti-TB, and antibacterial activities, and for cytotoxicity against both cancerous (MCF-7, KB, NCI-H187) and non-cancerous (Vero) cells. Compounds 1–7, 10–14 exhibited antimalarial (IC50 0.22–7.14 μg/ml), and elaiophylin analogs (4–6) displayed anti-TB (MIC 0.78–12.00 μg/ml) and B. cereus (MIC 0.78–3.13 μg/ml) activities. Compounds 1, 2, 14, and abierixin displayed weak cytotoxicity, indicating a potential for antimicrobial agents.
