Osmanicin, a Polyketide Alkaloid Isolated from Streptomyces osmaniensis CA-244599 Inhibits Elastase in Human Fibroblasts.


Institut de Chimie des Substances Naturelles ICSN, Centre National de la Recherche Scientifique, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France. [Email]


The strain Streptomyces osmaniensis CA-244599 isolated from the Comoros islands was submitted to liquid-state fermentation coupled to in situ solid-phase extraction with amberlite XAD-16 resin. Elution of the trapped compounds on the resin beads by ethyl acetate afforded seven metabolites, osmanicin (1), streptazolin (2), streptazone C (3), streptazone B1 (4), streptenol C (5), nocardamine (6) and desmethylenylnocardamine (7). Osmanicin (1) is a newly reported unusual scaffold combining streptazolin (2) and streptazone C (3) through a Diels-Alder type reaction. Experimental evidence excluded the spontaneous formation of 1 from 2 and 3. The isolated compounds were evaluated for their ability to inhibit elastase using normal human diploid fibroblasts. Compound 1 exhibited the most potent activity with an IC50 of 3.7 μM.


Streptomyces osmaniensis,alkaloids,elastase inhibition,in situ solid-phase extraction,osmanicin,

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