Hypoglycemic, Hypolipidemic and Histopathological Effects of Brown Seaweed (Sargassum Polycystum C. Agardh) Extracts on Type 2 Diabetic Rats

Diabetes mellitus is a serious global problem that is a major cause of disability and hospitalization in the world. This disorder is characterized by hyperglycemia and hyperlipidemia that are implicated in the development of microvascular and macrovascular complications. Recently, seaweeds have been the center of focus as a natural source of biological compounds useful for human health. Brown seaweed, Sargassum polycystum has been reported to be rich in biologically active substances with potential healing effects. In a preliminary study S. polycystum polar extract exhibited hypoglycemic and hypolipidemic effects on streptozotocin‐induced diabetic rats. The present study was carried out to investigate hypoglycemic and hypolipidemic effects of seaweed ethanolic and water extracts in type 2 diabetes rat model. Male Sprague‐Dawley rats (weighing 200–250 g) were divided into seven groups: normal control (NC) group fed with standard rodent diet (SRD) till the end of experiment, diabetic control (DC) group fed high‐sugar, high‐fat diet (HSHFD)for 16 weeks and then induced with 35 mg/kg body weight of streptozotocin (STZ), diabetic rats treated with 300 mg ethanolic extract/ kg body weight(DE300), diabetic rats treated with 150 mg ethanolic extract/ kg body weight (DE150), diabetic rats treated with 300 mg water extract/ kg body weight (DW300), diabetic rats treated with 150 mg water extract/ kg body weight (DW150), and diabetic rats treated with 250 mg metformin/ kg body weight (DM). Diabetes was induced in all diabetic groups by feeding rats with daily fresh prepared HSHFD for 16 weeks and then injection of low dose streptozotocin. Body weight, blood glucose level and serum lipid parameters were measured in 16 weeks. The HSHFD‐fed rats exhibited significant increase (P0.05) as compared to normal control group. Besides, homeostasis model assessment of insulin resistance (HOMA‐IR)showed significantly higher (P0.05) compared to DC, while treatment with metformin significantly (P<0.05) increased insulin level. There was a significant reduction (P<0.05) in the percentage of HbA1c in the DE300, DE150, DW300 and DM groups compared to DC group. All seaweed extracts reduced total cholesterol and triglyceride level significantly (P<0.05) compared to DC group. LDL‐C level was significantly (P<0.05) reduced in DW300 group compared to DC group. HDL‐C/TC ratio was significantly (P<0.05) improved in DE150, DW300, DW150 and DM groups compared to DC group. Pancreas histopathological results showed significantly (P<0.05) lower lesions in all treated groups compared with DC group. Moreover, regeneration of islets of Langerhans with more intact appearance was found in DE300, DW300 and DM groups compared with DC, DE150 and DW150 groups. However, DE150, DW150 and DM groups showed fewer lesions in the liver and kidney tissues compared to DC, DE300 and DW300 groups. High doses of both extracts have more hypoglycemic properties with better regeneration effects on pancreas than low doses. However, 150 mg/kg of seaweed ethanolic and water extracts caused fewer side effects on the liver and kidney tissues as compared to the high doses (300 mg/kg). Sargassum polycystum extracts showed good hypoglycemic and hypolipidemic effects with pancreas regeneration properties,hence may be potentially useful for the prevention of metabolic syndrome. It is preferably to be used at low dosage of about 150 mg/kg body weight, since higher dosage may cause some liver or kidney lesions. Keywords: Sargassum polycystum, Brown seaweed, Type 2 diabetes, Hypoglycemic, Hypolipidemic, Sprague‐Dawley

a-amylase from white pitaya Hylocereus undatus L. peel: optimization of extraction using full factorial design

Introduction. Amylase is a significant enzyme with numerous commercial applications, which is largely used to convert starches into oligosaccharides. Extraction of amylase from plant by-products or cheap sources is cost-effective. Annually, pitaya fruit juice industry produces huge amounts of peels that could be utilized as an alternative source in enzyme production industry. The work aimed to examine and optimize extraction process. Study objects and methods. In this study, we investigated parameters of extraction to optimize the process, as well as activity of α-amylase from white pitaya fruit (Hylocereus undatus L.) peel. For this purpose, a two-level full factorial design was applied. Three variables, namely the pH of sodium phosphate buffer (X1, 4.5–7.5), mixing time (X2, 1–3 min), and a sample-to-buffer ratio (X3, 1:3–1:5), were used to identify significant effects and interactions within the samples. Results and discussion. The results demonstrated that the buffer pH had the most significant (P ≤ 0.05) effect on total amylase activity. Based on full factorial design analysis, we revealed the optimal conditions for amylase enzyme extraction ‒ pH of 6, mixing time of 2 min, and a sample-to-buffer ratio of 1:4. Lower and higher values influenced adversely on specific activity of amylase. Conclusion. Optimization increased the enzyme specific activity by a factor of 4.5. Thus, pitaya peel could be used in different industries as a rich natural α-amylase source