Antioxidant and Inhibitory Effects of Saponin Extracts from Dianthus basuticus Burtt Davy on Key Enzymes Implicated in Type 2 Diabetes In vitro

Context: Dianthus basuticus is a plant of South African origin with various acclaimed pharmaceutical potentials. Aims: This study explored the antioxidant and antidiabetic activities of saponin extract from D. basuticus in vitro. Materials and Methods: Antioxidant activity of saponin was evaluated by 2,2‑diphenyl‑1‑picrylhydrazyl (DPPH) and nitric oxide (*NO)‑free radical scavenging activity while antidiabetic potentials were measured by the α‑amylase and α‑glucosidase inhibitory activities of the saponin extract. Results: The results showed that the saponin extract, compared with quercetin, displayed better DPPH (IC50 = 6.95 mg/ml) and NO (IC50 = 3.31 mg/ml) radical scavenging capabilities. Similarly, the saponin extracts elicited stronger α‑glucosidase (IC50 = 3.80 mg/ml) and moderate α‑amylase (IC50 = 4.18 mg/ml) inhibitory activities as compared to acarbose. Saponin exhibited a competitive mode of inhibition on α‑amylase with same maximum velocity (Vmax) of 0.0093 mM/min for saponin compared with control 0.0095 mM/min and different the Michaelis constant (Km) values of 2.6 × 10‑6 mM and 2.1 × 10‑5 mM, respectively, while for α‑glucosidase, the inhibition was uncompetitive, Vmax of 0.027 mM/min compared with control 0.039 mM/min and Km values of 1.02 × 10‑6 mM and 1.38 × 10‑6 mM, respectively. The gas chromatography‑mass spectrometric analysis revealed the presence of bioactive like β‑ and α‑amyrin, 3‑O‑methyl‑D‑glucose, methyl commate, and olean‑12‑en‑3‑beta‑ol. Conclusion: Overall, the data suggested that the saponin extract from D. basuticus has potentials as natural antioxidants and antidiabetics.