Synthesis of polyhydroxysterols (IV): synthesis of 24-methylene-cholesta-3β,5α,6β,19-tetrol, a cytotoxic natural hydroxylated sterol
摘要:
The cytotoxic, polyhydroxylated sterol 24-methylene-cholesta-3beta,5alpha,6beta,19-tetrol (1), previously isolated from the soft corals Nephthea albida and N. tiexieral verseveldt, was synthesized using stigmasterol as the starting material by 10 steps in 9% overall yield. The spectral data and physical constants of 1 were identical with those of the natural product. This is the first report of the synthesis of 1. (C) 2004 Elsevier Inc. All rights reserved.
Naturally occurring marine steroid 24-methylenecholestane-3β,5α,6β,19-tetraol functions as a novel neuroprotectant
摘要:
Steroids have been shown to have multiple effects on the nervous system including neuroprotective activities, and they have the potential to be used for the treatment of neurodegenerative diseases. In this current study, we tested the hypothesis that the marine steroid 24-methylenecholestane-3 beta,5 alpha,6 beta,19-tetraol (Tetrol) has a neuroprotective effect. (1) We synthesized Tetrol through a multiple step reaction starting from hyodeoxycholic acid (HDCA). (2) We then evaluated the neuroprotective effect of Tetrol with a glutamate-induced neuronal injury model in vitro. Tetrol concentration dependently increased the survival rate of cerebellar granule neurons challenged with toxic concentration of glutamate. Consistently, Tetrol significantly decreased glutamate-induced lactate dehydrogenase (LDH) release with a threshold concentration of 2.5 mu M. (3) We further evaluated the neuroprotective effect of Tetrol in a middle cerebral artery occlusion (MCAO)-induced cerebral ischemia model in rat. Tetrol, at a dose of 12 mg/kg, significantly decreased MCAO-induced infarction volume by similar to 50%. (4) Finally, we probed the mechanism and found that Tetrol concentration dependently attenuated N-methyl-D-aspartate (NMDA)-induced intracellular calcium ([Ca2+](i)) increase with an IC50 of 7.8 +/- 0.62 mu M, and inhibited NMDA currents in cortical neurons with an IC50 of 10.28 +/- 0.71 mu M. Taken together, we have synthesized and characterized Tetrol as a novel neuroprotectant through negative modulation of NMDA receptors. (C) 2015 Published by Elsevier Inc.
AKR1B10 is a member of the human aldo-keto reductase superfamily which is highly expressed in several types of cancers, and has been regarded as a promising cancer therapeutic target. In this paper, a series of polyhydroxy steroids were designed and synthesized to selectively inhibit AKR1B10 activity. The most selective compound, novel compound 6, has an IC50 of 0.83 +/- 0.07 mu M and a selectivity of more than 120-fold for AKR1B10/AKR1B1. Structure-activity relation analyses indicate that hydroxyl at C-19 can significantly improve the selective inhibition of AKR1B10. The binding mode of AKR1B10 and its inhibitors were studied. (C) 2016 Published by Elsevier Inc.