Phytochemical composition and antidiabetic potential of the leaf, stem, and rhizome extracts of Cissampelos capensis L.f

Abstract

Diabetes mellitus has a growing global prevalence and complications resulting from type 2 diabetes have been recorded to lead to death. The endemic medicinal plant Cissampelos capensis L.f. has been identified as an important plant in the management of diabetes by local people in southern Africa. The current work was designed to evaluate the in vitro cytotoxic, antioxidant, and α-amylase – and α-glucosidase inhibition of C. capensis based on its believed antidiabetic potential. The phytochemical analysis was performed through qualitative (HPTLC), and quantitative (UV–Vis spectrophotometry and LC-MS) analysis, while the in vitro MTT cytotoxicity, ORAC – and DPPH radical scavenging assays, α-glucosidase – and α-amylase inhibition potential of leaf, stem, and rhizome methanolic – (MCCL, MCCS, and MCCR) and TTA crude extracts (TTA CCL, TTA CCS, and TTA CCR) of C. capensis were accessed. Additionally, the cytotoxicity and enzymatic potential of five previously reported bioactive proaporphine alkaloids (glaziovine, pronuciferine, cissamaline, cissamanine, and cissamdine) isolated from C. capensis were evaluated. The phytochemical analysis revealed the highest presence of alkaloids followed by flavonoids, phenols, and terpenes. MCCL (93.740 ± 11.634 %), TTA CCS (77,818 ± 2,590 %), and TTA CCR (60,375 ± 12,722 %) exhibited the highest cell viability at 125 µg/mL, respectively, better than that of the positive control, Melphalan (62.5 µM). Where the The ORAC – and DPPH radical scavenging assays generally exhibited strong antioxidant activity for the rhizome and stem methanolic extracts. The α-glucosidase inhibition was strongest for the rhizome and stem extracts and comparable to that of the control. However, α-amylase inhibition was stronger for the leaf and rhizome extracts, and only comparable to the control at 500 µg/mL. All the isolated proaporphine alkaloids exhibited concentration dependant cytotoxicity, with moderate α-amylase inhibition at 500 µg/mL while no α-glucosidase inhibition was observed. The potential antioxidants and enzymatic inhibition combined with the moderate cytotoxicity of C. capensis and its isolated bioactive proaporphine alkaloids make it a good source of a possible new type II diabetic targets.