Abstract
A new cyclic hexapeptide, nocardiotide A (1), together with three known compounds—tryptophan (2), kynurenic acid (3), and 4-amino-3-methoxy benzoic acid (4)—were isolated and identified from the broth culture of Nocardiopsis sp. UR67 strain associated with the marine sponge Callyspongia sp. from the Red Sea. The structure elucidation of the isolated compounds were determined based on detailed spectroscopic data including 1D and 2D nuclear magnetic resonance (NMR) experimental analyses in combination with high resolution electrospray ionization mass spectrometry (HR-ESI-MS), while the absolute stereochemistry of all amino acids components of nocardiotide A (1) was deduced using Marfey’s method. Additionally, ten known metabolites were dereplicated using HR-ESI-MS analysis. Nocardiotide A (1) displayed significant cytotoxic effects towards the murine CT26 colon carcinoma, human HeLa cervix carcinoma, and human MM.1S multiple myeloma cell lines. The results obtained revealed sponge-associated Nocardiopsis as a substantial source of lead natural products with pronounced pharmacological activities.
Highlights
Actinomycetes are a diverse group of aerobic Gram-positive microorganisms withhigh guanine-cytosine DNA content [1]
UR67 was cultivated from the sponge Callyspongia sp
WasSea cultivated from the sponge sp. 27
Summary
Actinomycetes are a diverse group of aerobic Gram-positive microorganisms withhigh guanine-cytosine DNA content [1]. By reviewing the literature on the genus Nocardiopsis [9,10], it has α and γ-pyrones [19,20], naphthoquinones [21], phenazines [22], and phenoxazine derivatives [23], been clearly demonstrated that it is a prolific producer of a wide variety of bioactive compounds, whichmainly contributes to a broad spectrum of biological activities, mainly as cytotoxic [21], anticancer [22], cyclic peptides [11,12], polyketides [13,14], macrolides [15], alkaloids [16], diketopiperazines antitumor [11], antifungal [25],.
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