Abstract
The Catharanthus roseus plant has been used traditionally to treat diabetes mellitus. Scientific evidence supporting the antidiabetic effects of this plant’s active ingredient-vindoline has not been fully evaluated. In this study, extracts of C. roseus and vindoline were tested for antioxidant activities, alpha amylase and alpha glucosidase inhibitory activities and insulin secretory effects in pancreatic RIN-5F cell line cultured in the absence of glucose, at low and high glucose concentrations. The methanolic extract of the plant showed the highest antioxidant activities in addition to the high total polyphenolic content (p < 0.05). The HPLC results exhibited increased concentration of vindoline in the dichloromethane and the ethylacetate extracts. Vindoline showed noticeable antioxidant activity when compared to ascorbic acid at p < 0.05 and significantly improved the in vitro insulin secretion. The intracellular reactive oxygen species formation in glucotoxicity-induced cells was significantly reduced following treatment with vindoline, methanolic and the dichloromethane extracts when compared to the high glucose untreated control (p < 0.05). Plant extracts and vindoline showed weaker inhibitory effects on the activities of carbohydrate metabolizing enzymes when compared to acarbose, which inhibited the activities of the enzymes by 80%. The plant extracts also exhibited weak alpha amylase and alpha glucosidase inhibitory effects.
Highlights
Type 2 diabetes mellitus (T2DM) is a life-threatening disease of the endocrine system and its prevalence is on the rise owing to the increasing trends of obesity and sedentary lifestyles [1,2].These escalating trends have made diabetes mellitus (DM) a global epidemic as its burden is noticeable in both developed and developing regions [3]
Diabetes is a metabolic disorder where tissue damage arises from compromised antioxidant defense system and excessive build-up of ROS, plant derived compounds that are rich in polyphenols might possess better characteristics attributable to antidiabetic and antioxidant effects [19]
High performance liquid chromatography (HPLC) analysis of phenolic compounds and the alkaloid vindoline in C. roseus-aqueous (CR-Aq), C. roseus-methanolic (CR-Meth), C. roseus-ethyl acetate (CR-Ethyl) and C. roseus-dichlromethane (CR-DCM) extracts is represented in Table 1 and Appendix A (Figures A1–A12)
Summary
Type 2 diabetes mellitus (T2DM) is a life-threatening disease of the endocrine system and its prevalence is on the rise owing to the increasing trends of obesity and sedentary lifestyles [1,2]. These escalating trends have made diabetes mellitus (DM) a global epidemic as its burden is noticeable in both developed and developing regions [3]. Type 2 DM patients are vulnerable to complications that disrupt normal functions of the heart, kidneys, eyes, nerves and blood vessels [6]. It is undeniable that the use of orthodox drugs improved the management of T2DM but are associated with adverse
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