Mechanistic Evidence of Viscum schimperi (Viscaceae) Antihyperglycemic Activity: From a Bioactivity-guided Approach to Comprehensive Metabolite Profiling.

Diabetes mellitus is possibly the world's largest growing metabolic disorder. Effective treatment of diabetes is increasingly dependent on active constituents of medicinal plants capable of controlling hyperglycemia as well as its secondary complications. Viscum schimperi Engl. is a plant growing in Saudi Arabia and known for its antidiabetic activity. The potential antidiabetic activity of its methanol extract as well as its chloroform, n-butanol, and the remaining water fractions was evaluated in streptozotocin-induced diabetic rats at two dose levels. The antidiabetic activity was assessed through the determination of fasting blood glucose level, insulin levels, area under the curve (AUC) in oral glucose tolerance test, glucose absorption in isolated rat gut assay, and glucose uptake by psoas muscle. Moreover, large-scale untargeted metabolite profiling of methanol extract was performed via UPLC-PDA and qTOF-MS (ultra-performance liquid chromatography photodiode array detection and quadrupole time-of-flight mass spectrometry) respectively, to explore its chemical composition and standardization of its extract. Multivariate statistical analysis including principal component analysis and orthogonal projection to latent structures discriminant analysis was used to determine bioactives in its fractions. In conclusion, oleanane triterpenes and O-caffeoyl quinic acid conjugates were the major compounds that might account for antihyperglycemic effect of the plant.