New borrelidin derivatives from an endophytic Streptomyces sp.

New Borrelidins from Onchidium sp. Associated Streptomyces olivaceus SCSIO LO13

“…These results indicate that amidation at the C(22) position of the borrelidin scaffold reduces antibacterial activity against M. luteus and that hydroxylation at C(6) and C(8) abolish antimicrobial activity. Notably, these findings parallel those obtained during cytotoxicity assays and suggest some level of similarity between mechanisms of antimicrobial and cytotoxicity mechanisms/targets when it comes to borrelidin bioactivities …”

“…The structures of compounds 4 – 7 were readily identified as borrelidin A ( 4 ), borrelidin CR1 ( 5 ), borrelidin E ( 6 ) and borrelidin K ( 7 ) on the basis of comparisons of HR‐ESI‐MS, 1 H‐NMR, 13 C‐NMR data with those reported previously ( Figure ) …”

“…The borrelidins have attracted significant attention from the natural products community, and their noteworthy anti‐infective and cytotoxic activities have especially drawn the interest and efforts of biosynthetic and chemical synthesis researchers . In this study, three new borrelidins ( 1 – 3 ), along with four previously reported family members ( 4 – 7 ), were isolated from a likely associated symbiont S. olivaceus SCSIO LO13 from the marine pulmonated mollusk Onchidium sp.…”

“…Although borrelidin A ( 4 ) is toxic to non‐malignant cell types, its antitumor potential, as reflected in part by its ability to inhibit the growth of hepatocellular carcinoma cells, has garnered a significant amount of clinical interest . At the same time, a number of borrelidins with significantly improved cytotoxicities have been discovered and their activities correlated, at least in part, to specific structural modifications relative to borrelidin A ( 4 ) . In previous reports, we isolated borrelidins F–I from Streptomyces rochei SCSIO ZJ89 and some of these agents displayed significant cytotoxicities as well as anti‐metastasis activities …”

Bacterial pathogens: threat or treat (a review on bioactive natural products from bacterial pathogens)

“…82 A series of post-PKS tailoring enzymes such as ketoreductase (KR), methyltransferase (MT), enoyl reductase (ER), and dehydratase (DH) can variously modify the polyketide backbone, either while the intermediates are still bound to the assembly line or aer they are released. Installation of different polyketide starter and extender units also represents a signicant route to add unusual moieties such as nitrile functionality, carboxylates, and 84 and then more recently as a product of the potato pathogen Streptomyces GK18 85 and other Streptomyces species [86][87][88][89][90] as well as marine-derived microorganisms ( Fig. 2 and Table S1 †).…”