Asiatic acid derivatives protect primary cultures of rat hepatocytes against carbon tetrachloride-induced injury via the cellular antioxidant system.

We attempted to elucidate the hepatoprotective mechanism of two asiatic acid (AS) derivatives, 3beta,23-dihydroxyurs-2-oxo-12-ene-28-oic acid (AS-10) and 3beta,23-dihydroxyurs-12-ene-28-oic acid (AS-14), which exhibited significant protective activity against carbon tetrachloride (CCl4)-induced hepatotoxicity in primary cultures of rat hepatocytes. Our findings showed that AS-10 and AS-14 preserved the level of glutathione and the activities of antioxidant enzymes such as glutathione reductase, glutathione peroxidase, superoxide dismutase and catalase. In addition, these compounds ameliorated lipid peroxidation, as demonstrated by a reduction in the production of malondialdehyde.

Purification and characterization of antimicrobial peptides from the skin secretion of Rana dybowskii.

Six antimicrobial peptides designated dybowskins were isolated from the skin secretion of Rana dybowskii, an edible frog in Korea. Dybowskin-1 (FLIGMTHGLICLISRKC) and dybowskin-2 (FLIGMTQGLICLITRKC) were isoforms differing in only two amino acid residues at the 7th and 14th positions from the N-terminus, and they showed amino acid sequence similarities with ranalexin peptides. Dybowskin-3 (GLFDVVKGVLKGVGKNVAGSLLEQLKCKLSGGC), dybowskin-4 (VWPLGLVICKALKIC), dybowskin-5 (GLFSVVTGVLKAVGKNVAKNVGGSLLEQLKCKISGGC), and dybowskin-6 (FLPLLLAGLPLKLCFLFKKC) differed in both size and sequence, and they were, in terms of amino acid sequence similarities, related to brevinin-2, japonicin-2, esculentin-2, and brevinin-1 peptides, respectively.

Synthesis of 6-formyl-pyridine-2-carboxylate derivatives and their telomerase inhibitory activities.

Twenty-one pyridine-2-carboxylate derivatives were prepared by the coupling of 6-formyl-2-carboxylic acid with the corresponding phenol, thiophenol, and aniline, substituted with various functional groups. Among them, the 3,4-dichlorothiophenol ester (9p) showed the highest in vitro telomerase inhibitory activity and quite significant in vivo tumor suppression activity.