The present study investigated the antidiabetic and antioxidant capacity of hydromethanol extract from Parkia biglobosa stem bark (PBSBHM) in fructose-streptozotocin induced type 2 diabetic rats after 28 days of oral administration. Simultaneously, evaluated the phenolic profiles and mineral compositions of crude extract. Molecular docking analysis of protocatechuic acid, the most abundant phenolic acid with potential downstream partners protein kinase A (PKA), protein kinase C (PKC), and Ca2+/calmodulin-dependent protein kinase II (CaMK II), was investigated. The preliminary results showed that PBSBHM crude extract contained 225.2 ± 18.25 mg GAE/g of total phenolic and 99.28 ± 12.3 mg QE/g of total flavonoid. Both protocatechuic and gallic acids were identified as a prominent phenolic compound through HPLC analysis, while vanillic acid was not detected. High mineral composition of K, Mg, P, Ca while Mn and Cr as trace elements were found in PBSBHM by plasma optical emission spectroscopy. PBSBHM extracts showed a significant radical scavenging activity from a therapeutic point of view, a moderate antioxidant potential and improved glucose tolerance after 30 min of glucose loading. PBSBHM extracts significantly attenuated serum glucose level and glycosylated haemoglobin at the tested dosage. However, it elevated the hepatic hexokinase activity and glycogen level compared with the diabetic untreated rats. PBSBHM ameliorates the decreased activity of pancreatic superoxide dismutase, catalase and reduced glutathione but decreased the MDA level. Docking analysis of protocatechuic acid showed a moderate affinity for the target enzymes compared to the standard drugs. Our data showed that the stem bark extract of this botanical has antidiabetic potential and at least in part substantiates its traditional use in the management of diabetes, possibly due to the synergistic interactions of protocatechuic acid with other biologically active components.
Keywords: Parkia biglobosa; antioxidant; mineral analysis; molecular docking; phenolic acids; type 2 diabetes.