ABSTRACT
Cyclooxygenases play a vital role in inflammation and are responsible for the production of prostaglandins. Two cyclooxygenases are described, the constitutive cyclooxygenase-1 and the inducible cyclooxygenase-2, for which the target inhibitors are the non-steroidal anti-inflammatory drugs (NSAIDs). Prostaglandins are a class of lipid compounds that mediate acute and chronic inflammation. NSAIDs are the most frequent choices for treatment of inflammation. Nevertheless, currently used anti-inflammatory drugs have become associated with a variety of adverse effects which lead to diminished output even market withdrawal. Recently, more studies have been carried out on searching novel selective COX-2 inhibitors with safety profiles. In this review, we highlight the various structural classes of organic and natural scaffolds with efficient COX-2 inhibitory activity reported during 2011-2021. It will be valuable for pharmaceutical scientists to read up on the current chemicals to pave the way for subsequent research.
ABSTRACT
Filamentous soil bacteria are known to produce diverse specialized metabolites. Despite having enormous potential as a source of pharmaceuticals, they often produce bioactive metabolites at low titers. Here, we show that inactivation of the pactamycin, NFAT-133, and conglobatin biosynthetic pathways in Streptomyces pactum ATCC 27456 significantly increases the production of the mitochondrial electron transport inhibitors piericidins. Similarly, inactivation of the pactamycin, NFAT-133, and piericidin pathways significantly increases the production of the heat-shock protein (Hsp) 90 inhibitor conglobatin. In addition, four new conglobatin analogues (B2, B3, F1, and F2) with altered polyketide backbones, together with the known analogue conglobatin B1, were identified in this mutant, indicating that the conglobatin biosynthetic machinery is promiscuous toward different substrates. Among the new conglobatin analogues, conglobatin F2 showed enhanced antitumor activity against HeLa and NCI-H460 cancer cell lines compared to conglobatin. Conglobatin F2 also inhibits colony formation of HeLa cells in a dose-dependent manner. Molecular modeling studies suggest that the new conglobatins bind to human Hsp90 and disrupt Hsp90/Cdc37 chaperone/co-chaperone interactions in the same manner as conglobatin. The study also showed that genes that are involved in piericidin biosynthesis are clustered in two different loci located distantly in the S. pactum genome.
