This study was designed to investigate the role of graded doses of lipoic acid pretreatment against cisplatin-induced nephrotoxicity. Male Wistar rats were divided into six groups and treated as follows: 1) vehicle (saline) control; 2) cisplatin (16 mg/kg, intraperitoneally); 3) lipoic acid (100 mg/kg, intraperitoneally); 4) cisplatin plus lipoic acid (25 mg/kg); 5) cisplatin plus lipoic acid (50 mg/kg) and 6) cisplatin plus lipoic acid (100 mg/kg). Rats were sacrificed three days after treatment, and plasma as well as kidneys were isolated and analyzed. Plasma creatinine increased (677% of control) following cisplatin administration alone which was decreased by lipoic acid in a dose-dependent manner. Cisplatin-treated rats showed a depletion of renal glutathione (GSH), increased oxidized GSH and decreased GSH/GSH oxidized ratio (62%, 166% and 62% of control), respectively which were restored with lipoic acid pretreatment. Renal superoxide dismutase, catalase, glutathione peroxidase (GSH peroxidase) and glutathione reductase activities decreased (62%, 75%, 62% and 80% of control), respectively, and malondialdehyde content increased (204% of control) following cisplatin administration, which were restored with increasing doses of lipoic acid. The renal platinum concentration increased following cisplatin administration, which was possibly decreased by chelation with lipoic acid. The data suggest that the graded doses of lipoic acid effectively prevented a decrease in renal antioxidant defense system and prevented an increase in lipid peroxidation, platinum content and plasma creatinine concentrations in a dose-dependent manner.

This study was designed to investigate the role of graded doses of lipoic acid pretreatment against cisplatininduced nephrotoxicity. Male Wistar rats were divided into six groups and treated as follows: 1) vehicle (saline) control; 2) cisplatin (16 mg/kg, intraperitoneally); 3) lipoic acid (100 mg/kg, intraperitoneally); 4) cisplatin plus lipoic acid (25 mg/ kg); 5) cisplatin plus lipoic acid (50 mg/kg) and 6) cisplatin plus lipoic acid (100 mg/kg). Rats were sacrificed three days after treatment, and plasma as well as kidneys were isolated and analyzed. Plasma creatinine increased (677% of control) following cisplatin administration alone which was decreased by lipoic acid in a dose-dependent manner. Cisplatin-treated rats showed a depletion of renal glutathione (GSH), increased oxidized GSH and decreased GSH/GSH oxidized ratio (62%, 166% and 62% of control), respectively which were restored with lipoic acid pretreatment. Renal superoxide dismutase, catalase, glutathione peroxidase (GSH peroxidase) and glutathione reductase activities decreased (62%, 75%, 62% and 80% of control), respectively, and malondialdehyde content increased (204% of control) following cisplatin administration, which were restored with increasing doses of lipoic acid. The renal platinum concentration increased following cisplatin administration, which was possibly decreased by chelation with lipoic acid. The data suggest that the graded doses of lipoic acid effectively prevented a decrease in renal antioxidant defense system and prevented an increase in lipid peroxidation, platinum content and plasma creatinine concentrations in a dose-dependent manner.

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Olefinic ß-keto esters 8, 17, and 20, prepared by either carbomethoxylation of the parent ketone or alkylation of the dianion of methyl acetoacetate with the allylic bromide, underwent cyclization with stannic chloride in dichloromethane to give mono-and bicyclic keto esters 10 and 18, respectively. The latter was transformed via ketone 24 to A8(u)-podocarpen-13-one ( 27) and to keto acid 29, an intermediate in the synthesis of ambreinolide. Keto ester 46, prepared by condensation of the dianion of methyl acetoacetate with ß-cyclocitral, gave 56 as the major product upon irradiation in neutral solution but, in the presence of sodium methoxide, a mixture (ca. 1:1) of 45 and 65 was produced in 66% yield. Enol derivatives 52, 53, and 54 of 46 underwent 1,5-hydrogen migration upon photolysis to give 55, 58, and 59. The dark transformation of 56 to 47 with triethylamine revealed a pathway to this pyranoid structure unrecognized in previous photochemical studies of ß-ionone, and the conversion of 47 to 45 and 65 upon irradiation in the presence of sodium methoxide suggests a mechanistic hypothesis for these light-induced reactions involving a manifold of equilibrating enolates which terminate at 45.