Abstract

To investigate the pharmacokinetic characteristics of bisdemethoxycurcumin in vivo and the reversal effect of phosphatidylinositol 3-kinase/protein kinase B/caspase-9 signaling pathway on thapsigargininduced cardiomyocyte apoptosis in neonatal rat. Demethoxycurcumin and bisdemethoxycurcumin were intragastrically administered to adult Sprague–Dawley rats. Plasma was collected and the drug concentration was measured by high performance liquid chromatography. The pharmacokinetic parameters of the drug were calculated by Drug and Statistics 2.1.1 pharmacokinetic software. After that, primary cardiomyocytes from Sprague–Dawley neonatal rats were isolated and cultured, and they were divided into three groups; control (conventional culture without any drug treatment), model (endoplasmic reticulum stress model obtained by treatment with 1 mg/ml thapsigargin for 24 h), demethoxy curcumin group (treated with 1 μmol/l thapsigargin and 10 μmol/l demethoxy curcumin for 24 h at the same time) and bisdemethoxycurcumin group (treated with 1 μmol/l thapsigargin and 10 μmol/l bisdemethoxycurcumin for 24 h at the same time). Cell survival activity was measured by cell counting kit-8 assay. Western blot was used to detect the expression of intracellular apoptotic factors Bcl-2-associated X, B-cell lymphoma protein 2 and B-cell lymphoma protein 2/Bcl-2-associated X protein and the expression levels of phosphatidylinositol 3-kinase/protein kinase B/caspase-9 signaling pathway molecules phosphatidylinositol 3-kinase, protein kinase B, caspase-3 and caspase-9 protein. The results showed that the main pharmacokinetic parameters area under the timeconcentration curve 0-12 h, mean residency time 0-12 h, maximum plasma concentration, time to maximum plasma concentration of demethoxycurcumin and bisdemethoxycurcumin were (1.35±0.36) μg/ml•h and (1.01±0.14) μg/ml•h, (4.05±0.53) h and (3.43±0.21) h, (0.46±0.09) μg/ml and (0.45±0.11) μg/ml, (0.14±0.00) h and (0.20±0.00) h, respectively. In contrast with the model group, the survival activity of demethoxycurcumin and bisdemethoxycurcumin groups was significantly increased, the apoptosis rate was significantly decreased; the lactate dehydrogenase, malondialdehyde content and reactive oxygen species level were decreased, the superoxide dismutase activity was increased, the Bcl-2-associated X, caspase-3 and caspase-9 protein expression was decreased and the B-cell lymphoma protein 2/Bcl-2-associated X, phosphatidylinositol 3-kinase and protein kinase B protein expression was increased (p<0.05). However, bisdemethoxycurcumin was slightly superior to demethoxycurcumin in improving the above indicators, but the difference was not statistically meaningful (p>0.05). In summary, demethoxy curcumin and bisdemethoxycurcumin can mediate phosphatidylinositol 3-kinase/protein kinase B/caspase-9 signaling pathway to reduce thapsigargin-induced endoplasmic reticulum stress injury in cardiomyocytes, which in turn plays a protective role in cardiomyocytes.