Search results for "Polyketides"
showing 5 items of 15 documents
Enantioselective Total Syntheses of (+)-Hippolachnin A, (+)-Gracilioether A, (-)-Gracilioether E and (-)-Gracilioether F
2018
The Plakortin polyketides represent a structurally and biologically fascinating class of marine natural products. Herein, we report a unified strategy that enables the divergent syntheses of various Plakortin polyketides with high step-economy and overall efficiency. As proof-of-concept cases, the enantioselective total syntheses of (+)-hippolachnin A, (+)-gracilioether A, (−)-gracilioether E, and (−)-gracilioether F have been accomplished based on a series of bio-inspired, rationally designed, or serendipitously discovered transformations, which include (1) an organocatalytic asymmetric 1,4-conjugate addition to assemble the common chiral γ-butenolide intermediate enroute to all of the afo…
Bioactive polyketides and alkaloids from Penicillium citrinum , a fungal endophyte isolated from Ocimum tenuiflorum
2013
Chemical investigation of the endophytic fungus Penicillium citrinum cultured on white beans or on rice led to the isolation of two new alkaloids (1 and 2), along with fourteen known polyketides (6-12, 14-20) and four known alkaloids (3-5, and 13). The structures of the isolated compounds were determined by extensive analysis of the 1D, 2D NMR, and MS data, and by comparison with the literature. Compound 13, which had been previously obtained only by chemical synthesis, was isolated as a natural product for the first time, while compound 6 was firstly reported as a fungal metabolite. A re-isolation of sclerotinin A (14) revealed it to be a diastereoisomeric mixture (14a and 14b), whose ster…
Dihydroisocoumarins, Naphthalenes, and Further Polyketides from Aloe vera and A. plicatilis: Isolation, Identification and Their 5-LOX/COX-1 Inhibiti…
2021
The present study aims at the isolation and identification of diverse phenolic polyketides from Aloe vera (L.) Burm.f. and Aloe plicatilis (L.) Miller and includes their 5-LOX/COX-1 inhibiting potency. After initial Sephadex-LH20 gel filtration and combined silica gel 60- and RP18-CC, three dihydroisocoumarins (nonaketides), four 5-methyl-8-C-glucosylchromones (heptaketides) from A. vera, and two hexaketide-naphthalenes from A. plicatilis have been isolated by means of HSCCC. The structures of all polyketides were elucidated by ESI-MS and 2D 1H/13C-NMR (HMQC, HMBC) techniques. The analytical/preparative separation of 3R-feralolide, 3′-O-β-d-glucopyranosyl- and the new 6-O-β-d-glucopyranosyl…
Tanzawaic acids I-L: Four new polyketides from Penicillium sp. IBWF104-06.
2014
Four new polyketides have been identified in culture filtrates of the fungal strain Penicillium sp. IBWF104-06 isolated from a soil sample. They are structurally based on the same trans-decalinpentanoic acid skeleton as tanzawaic acids A–H. One of the new compounds was found to inhibit the conidial germination in the rice blast fungus Magnaporthe oryzae at concentrations of 25 μg/mL.
The swinholide biosynthetic gene cluster from a terrestrial cyanobacterium Nostoc sp. UHCC 0450
2018
Swinholides are 42-carbon ring polyketides with a 2-fold axis of symmetry. They are potent cytotoxins that disrupt the actin cytoskeleton. Swinholides were discovered from the marine sponge Theonella sp. and were long suspected to be produced by symbiotic bacteria. Misakinolide, a structural variant of swinholide, was recently demonstrated to be the product of a symbiotic heterotrophic proteobacterium. Here, we report the production of swinholide A by an axenic strain of the terrestrial cyanobacterium Nostoc sp. strain UHCC 0450. We located the 85-kb trans-AT polyketide synthase (PKS) swinholide biosynthesis gene cluster from a draft genome of Nostoc sp. UHCC 0450. The swinholide and misaki…