Published in

MDPI, Molecules, 12(24), p. 2239, 2019

DOI: 10.3390/molecules24122239



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

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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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.