Context: Dracocephalum polychaetum Bornm. (Lamiaceae) is used in folk medicine and contains antioxidant agents.
Objectives: The objective of this study is to investigate the antidiabetic, antioxidant, and antilipid peroxidative properties of methanol extract of D. polychaetum aerial parts.
Materials and methods: The effect of extract (200, 300, and 400 mg/kg, b.w.) on oral glucose tolerance test (OGTT) was investigated. Also, extract (300 mg/kg) administered orally in diabetic rats for 14 d then, serum levels of some biochemical factors were evaluated. Pancreas samples were used for the determination of malondealdehyde (MDA) level, glutathione (GSH) content, superoxide dismutase, and catalase enzyme activities. Red blood cells (RBCs) and plasma were used for MDA estimation. Pancreatic α-amylase inhibition, DPPH (1,1-diphenyl-2-picrylhydrazyl), and FRAP (ferric reducing antioxidant power) assays were done. The total flavonoid content of the extract was determined by spectrophotometry.
Results: Extract (300 mg/kg) decreased serum glucose level (27.1%) significantly at 120 min in OGTT. Serum levels of creatinine, triglycerides, cholesterol, alanine amino transferase and MDA levels in plasma, RBCs, and pancreas significantly decreased in treated (300 mg/kg) diabetic rats, while pancreatic GSH content, superoxide dismutase, and catalase enzymatic activities increased (p < 0.05). The IC50 values for the extract and butyl hydroxyanisole were 5.6 and 1.15 mg/mL in DPPH and 0.155 and 0.062 mg/mL in the FRAP methods, respectively. The extract had no inhibitory effect on α-amylase activity. The total amount of flavonoids of the extract was estimated to be 1.8% (g/g) on the basis of quercetin content.
Conclusion: Dracocephalum polychaetum shoot extract has antioxidant, antihyperlipidemic, and antilipid peroxidative properties.
Keywords: Alpha-amylase inhibitory activity; MDA; diabetes mellitus; medicinal plants; pancreas.