Euphol, a tetracyclic triterpene produces antinociceptive effects in inflammatory and neuropathic pain: the involvement of cannabinoid system.

Persistent pains associated with inflammatory and neuropathic states are prevalent and debilitating diseases, which still remain without a safe and adequate treatment. Euphol, an alcohol tetracyclic triterpene, has a wide range of pharmacological properties and is considered to have anti-inflammatory action. Here, we assessed the effects and the underlying mechanisms of action of euphol in preventing inflammatory and neuropathic pain. Oral treatment with euphol (30 and 100 mg/kg) reduced carrageenan-induced mechanical hyperalgesia. Likewise, euphol given through the spinal and intracerebroventricular routes prevented mechanical hyperalgesia induced by carrageenan. Euphol consistently blocked the mechanical hyperalgesia induced by complete Freund's adjuvant, keratinocyte-derived chemokine, interleukin-1ß, interleukin-6 and tumor necrosis factor-alpha associated with the suppression of myeloperoxidase activity in the mouse paw. Oral treatment with euphol was also effective in preventing the mechanical nociceptive response induced by ligation of the sciatic nerve and also significantly reduced the levels and mRNA of cytokines/chemokines in both paw and spinal cord tissues following i.pl. injection of complete Freund's adjuvant. In addition, the pre-treatment with either CB1R or CB2R antagonists, as well as the knockdown gene of the CB1R and CB2R, significantly reversed the antinociceptive effect of euphol. Interestingly, even in higher doses, euphol did not cause any relevant action in the central nervous system. Considering that few drugs are currently available for the treatment of chronic pain states, the present results provided evidence that euphol constitutes a promising molecule for the management of inflammatory and neuropathic pain states.

Utilization of target-specific, hypersensitive strains of Saccharomyces cerevisiae to determine the mode of action of antifungal compounds.

Target-specific hypersusceptible strains of Saccharomyces cerevisiae were used to screen antifungal compounds. Two novel Erg7p inhibitors were identified, providing proof of principle of the approach taken. However, observed hypersensitivities to antifungals acting via other targets imply that use of this tool to identify the mode of action requires significant deconvolution.

Inhibitors of sterol biosynthesis and amphotericin B reduce the viability of pneumocystis carinii f. sp. carinii.

Pneumocystis carinii synthesizes sterols with a double bond at C-7 of the sterol nucleus and an alkyl group with one or two carbons at C-24 of the side chain. Also, some human-derived Pneumocystis carinii f. sp. hominis strains contain lanosterol derivatives with an alkyl group at C-24. These unique sterols have not been found in other pathogens of mammalian lungs. Thus, P. carinii may have important differences in its susceptibility to drugs known to block reactions in ergosterol biosynthesis in other fungi. In the present study, inhibitors of 3-hydroxy-3-methyglutaryl coenzyme A reductase, squalene synthase, squalene epoxidase, squalene epoxide-lanosterol cyclase, lanosterol demethylase, Delta(8) to Delta(7) isomerase, and S-adenosylmethionine:sterol methyltransferase were tested for their effects on P. carinii viability as determined by quantitation of cellular ATP levels in a population of organisms. Compounds within each category varied in inhibitory effect; the most effective included drugs targeted at squalene synthase, squalene epoxide-lanosterol cyclase, and Delta(8) to Delta(7) isomerase. Some drugs that are potent against ergosterol-synthesizing fungi had little effect against P. carinii, suggesting that substrates and/or enzymes in P. carinii sterol biosynthetic reactions are distinct. Amphotericin B is ineffective in clearing P. carinii infections at clinical doses; however, this drug apparently binds to sterols and causes permeability changes in P. carinii membranes, since it reduced cellular ATP levels in a dose-dependent fashion.

Cholesterol biosynthesis from lanosterol: differential inhibition of sterol delta 8-isomerase and other lanosterol-converting enzymes by tamoxifen.

The fact that administration of tamoxifen (Tam) to humans and laboratory animals (e.g., rats and monkeys) results in both a drastic reduction in cholesterol and a marked accumulation of certain sterol intermediates in their serum led us to undertake more direct biochemical studies on the mechanism of Tam's inhibitory action on the cholesterogenic enzymes. Of the five rat hepatic lanosterol-converting enzymes examined, the enzyme most sensitive to inhibition by Tam was sterol delta 8-isomerase (delta 8-SI) (a 208-fold inhibition relative to lanosterol 14 alpha-methyl demethylase), followed by sterol delta 24-reductase (13-fold) and sterol delta 14-reductase (5.2-fold). The inhibition patterns of all four affected enzymes were found to be noncompetitive, despite widely different inhibition constants (Ki) of 0.21 to 23.5 microM. The inhibitory activity of Tam on delta 8-SI was not affected by detergent-mediated solubilization of the microsomes. In Chinese hamster ovary cells, inhibition of delta 8-SI activity (IC50 = 0.15 microM) was paralleled by a decreased rate of [14C]-mevalonate incorporation into cholesterol (IC50 = 0.70 microM). Our results should provide more insight into an underlying mechanism of Tam's cardioprotective role by interfering the operation of the pathway of cholesterol biosynthesis from lanosterol in mammals.