Antioxidant properties of Aloe vera components: a DFT theoretical evaluation.

Prediction of the antioxidant activity of three Aloe vera components (aloesone, aloe-emodin, and isoeleutheol) was performed based on density functional theory calculations using the B3LYP hybrid functional and the 6-311++ G** basis set. Calculation of highest occupied molecular orbital (HOMO), lowest occupied molecular orbital (LUMO), and Egap revealed that aloe-emodin has the lowest Egap value, indicating good antioxidant activity. Also in terms of electron affinity, softness, electrophilicity, and chemical potential, aloe-emodin is a potent structure with potential high radical scavenging activity. Calculation of the ionisation potential revealed that isoeleutherol likely also possesses a high degree of antiradical scavenging. To study the conjugating system of the radicals, density plots of HOMO, natural bond orbital analyses, and spin density plots were used. According to calculations, the isoeleutherol radical is more delocalised and the most stable radical. Calculated proton affinity values revealed that the most probable antioxidant mechanism is sequential proton loss-electron transfer. Our results were compared with available experimental data. Published experimental data were found to correlate well with our theoretical predictions. These results support the usefulness of theoretical calculations not only for identifying potentially useful structures of studied compounds but also for predicting their relative activity.

Palmitate-induced insulin resistance is attenuated by Pioglitazone and EGCG through reducing the gluconeogenic key enzymes expression in HepG2 cells.

HYPOTHESIS: Palmitate causes insulin resistance (IR) in insulin target tissue. Pioglitazone (an anti-hyperglycemic agent) and epigallocatechin gallate (EGCG, a dietary supplement) can be used for the treatment of type 2 diabetes. However, their molecular effects on gluconeogenesis remain unclear. OBJECTIVE: Hence, we aimed to investigate the simultaneous effect of these anti-hyperglycemic agents on gluconeogenesis through in vitro experiments. METHODS: HepG2 cells were treated with 0.5 mM palmitate, 10 µM pioglitazone, and 40 µM epigallocatechin gallate (EGCG). Gene expression assay was used to investigate the underlying mechanism. Glucose production assay was applied in culture medium to evaluate the activity of gluconeogenesis pathway. RESULTS: Palmitate induced IR could significantly increase G6Pase and PEPCK gene expressions by 58 and 30%, respectively, compared to the control. EGCG reduced the expression of PEPCK and G6Pase by 53 and 67%, respectively. Pioglitazone reduced the mRNA level of PEPCK and G6Pase by 58 and 62% respectively. Combined treatment of insulin-resistant cells with EGCG and pioglitazone significantly decreased the mRNA level of PEPCK and G6Pase by 73 and 80%, respectively. Treatment with palmitate increased glucose production by 50% in HepG2 cells. When the insulin resistant HepG2 cells were treated alone with EGCG and pioglitazone, the glucose production reduced by 50 and 55%, respectively. The combined treatment with EGCG and pioglitazone resulted in 69% reduction in glucose production compared to the palmitate treated HepG2 cells. CONCLUSIONS: These data suggest the additive inhibitory effect of co-treatment with pioglitazone and EGCG on the gluconeogenesis pathway in palmitate-induced insulin resistance HepG2 cells.

In vitro cultivation of axenic amastigotes and the comparison of antioxidant enzymes at different stages of Leishmania tropica.

The present study aimed to establish a simple method to yield large amounts of Leishmania tropica amastigote-like forms in axenic cultures and to compare the superoxide dismutase (SOD) and glutathione peroxidase (GPX) enzymes at different stages of L. tropica. Different culture conditions were tested to find the optimum condition of axenic amastigotes generation. Superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities were determined at logarithmic and stationary phases and axenic amastigote stage of the parasite. A high proportion (88%) of amastigote-like forms of L. tropica was observed in BHI medium supplemented with 20% FCS, pH 4.5, and incubated at 37ºC with 5% CO(2). The results showed that SOD activity was at the lowest level in the logarithmic phase of promastigotes and increased towards the stationary phase of promastigotes and amastigote stage. The results showed that the optimum condition for differentiation of L. tropica promastigotes to axenic amastigotes was BHI medium containing 20% FCS at pH 4.5, incubated at 37ºC in the presence of 5% CO(2). It seems that SOD, but not GPX is a major determinant of intracellular survival of the parasite.