This study sought to investigate the possible protective role of Parkia biglobosa seed protein isolate (PBPi) against streptozotocin-induced hepatic damage and oxidative stress in diabetic male rats. Prior to animal experiments, a HPLC fingerprint of PBPi was recorded. Diabetes was induced in rats by a single intraperitoneal injection of streptozotocin (STZ; 60 mg/kg body weight). Diabetic rats were orally treated daily with PBPi (200 or 400 mg/kg body weight) or insulin (5 U/kg, i.p.) for 28 days. The degree of protection was evaluated using biochemical parameters such as malondialdehyde (MDA) levels, serum transaminases (ALT and AST), total protein, total glutathione (Total GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), and interleukin-6 (IL-6) activities. Histology of liver sections was also performed. The HPLC fingerprint of PBPi revealed eleven distinct peaks; PBPi at tested doses significantly attenuates STZ-induced elevated levels of serum IL-6, ALT and AST; and hepatic TBARS levels. Hepatic antioxidants (Total GSH, GST, SOD, CAT) as well as total protein were markedly restored in a dose-dependent manner. Histopathological results strongly support the protective role of PBPi. These results suggest PBPi could confer protection by ameliorating hepatic damage and oxidative stress caused by STZ in animal model possibly via its anti-inflammatory and antioxidant properties.

Reports from previous studies now provide evidence that dyslipidaemia and oxidative stress play crucial roles in the pathogenesis and progression of diabetes and its related complications. This research is aimed to investigate the potential effects of protein isolate from Parkia biglobosa seeds (PBPI) in streptozotocin (STZ)-induced diabetic rats by measuring blood glucose levels, changes in lipid metabolism and biomarkers of oxidative stress. Diabetic rats were treated orally with graded doses of PBPI, 200 mg/kg bw and 400 mg/kg bw, and 5 U/kg, intraperitoneal (i.p.) of insulin once daily for 28 days with the fasting blood glucose (FBG) monitored weekly. The effect of PBPI on the serum lipid profile was measured while the extent of lipid peroxidation (LPO), as well as antioxidant parameters (superoxide dismutase; SOD, catalase; CAT, glutathione-S-transferase; GST and total glutathione; total GSH), was determined in the cardiac homogenates of diabetic rats. At the tested doses, treatment with PBPI was significantly effective in lowering FBG, serum triglyceride, cholesterol, low-density lipoprotein cholesterol (LDL-c) and very low-density lipoprotein cholesterol (VLDL-c), while concurrently increasing high-density lipoprotein cholesterol (HDL-c). PBPI also significantly decreased the elevations witnessed in LPO levels and restored the biomarkers of oxidative stress in the cardiac homogenate of experimental rats. The results from this study demonstrate that PBPI could improve dyslipidaemia and cardiac oxidative stress in the experimental diabetic animal model possibly by reducing and effectively scavenging reactive oxygen species (ROS) production as well as by increasing antioxidant capacity in combating oxidative stress. Therefore, it can be concluded that PBPI could be explored in the development of a potent cardioprotective supplement or adjuvant therapy towards the management of diabetes and its related complications.

Protein isolate from Parkia biglobosa seeds is believed to possess excellent anti-diabetic properties. The purpose of this study was to identify differentially expressed proteins in liver of streptozotocin-induced diabetic rats treated with Parkia biglobosa seeds protein isolate (PBPi). In this study, total proteins extracted from rat liver were separated on one-dimensional SDS polyacrylamide gel (1D SDS-PAGE) and stained with Coomassie brilliant blue (CBB) to visualize protein bands. We observed that protein bands in the region of 10–15 kDa were altered by the different treatments; these bands were selected and excised for in-gel digestion and peptide extraction followed by nLC-MS, MALDI-TOF MS, and LIFT MS/MS. A database search with the Mascot algorithm positively identified four differentially expressed proteins. These proteins are known to be responsible for diverse biological functions within various organs and tissues. The present result gives insight and understanding into possible molecular mechanisms by which streptozotocin causes various alterations in proteins found in the liver of diabetic rats and the possible modulatory role of PBPi in the management of streptozotocin-induced diabetes.

Parkia biglobosa (PB) is among the various underexploited nutritious plants. A comparative study was conducted on the effect processing PB has on the amino and fatty acid composition. Fermented (FPB), defatted (DPB), and protein isolates (PI) samples were prepared from Parkia biglobosa seeds using various processing methods, and evaluated using standard analytical protocols. The PI showed the highest significant total non-essential amino acids, essential amino acids, and conditionally essential amino acids when compared with FPB and DPB. In addition, the PI showed the highest significant (p < 0.05) total neutral amino acids, basic amino acids, total aromatic amino acids, and the lowest percentage cystine ratio of total sulphur amino acids and total amino acids in comparison with FPB and DPB. The PI also showed a better-predicted protein efficient ratio, essential amino acid index, biological value, protein content, and nutritional index than FPB and DPB. Furthermore, PI amino acid composition was compared favourably with the reference scores for a whole hen’s egg, preschool child, and provisional scoring pattern. Arginine and histidine values of PI were higher than the recommended values. The FPB (42.29%) showed the highest polyunsaturated fatty acids compared with the DPB (41.94%) and PI (26.7%). The dominant saturated, monounsaturated, and polyunsaturated fatty acids were stearic acid (15.1 DPB), linoleic acid (42.29 DPB), and oleic acid (14.05 PI). The DPB (1.84) showed a better polyunsaturated to saturated (P:S) ratio than FPB (1.74) and PI (0.91). The results revealed that the processing methods improved the relative amino acid composition, whereas the fatty acid composition improved in DPB. Therefore, PI could serve as an alternative in the formulation of complementary foods.