Phytochemicals, Cytotoxicity, Inhibitory Effect on Nitric Oxide Production and Alpha-Glucosidase Activity, and DPPH Scavenging Activity of Leaf Extract from Gymnema inodorum (Lour.) Decne

Abstract

Investigation of phytochemicals, cyto-toxicity, inhibitory effect on nitric oxide (NO) production and α-glucosidase activity, and DPPH scavenging activity of leaf extract from Gymnema inodorum (Lour.) Decne (LEGI) revealed that GC-MS analysis demonstrated the presence of 83 phytochemicals with 5 main compounds i.e. Phytol (18.14 %), n-Hexadecanoic acid (12.45 %), 9,12-Octadecadienoic acid (Z,Z)-(3.92 %), 9,12,15-Octadecatrienoic acid, (Z,Z,Z)-(10.39 %) and Betulin (8.56 %), and 78 trace compounds in LEGI. MTT assay to investigate cytotoxicity showed that LEGI exhibited low cytotoxicity to the RAW 264.7 macrophages with IC50 of 128.77±2.82 µg/mL. Treatment with the LEGI significantly inhibited nitric oxide (NO) production, an inflammatory mediator, in the LPS-stimulated RAW 264.7 cells. At the concentration of 50 mg/mL, LEGI inhibited NO production by 16.73±1.52 % which was less than Diclofenac did (27.07±1.81 %). The α-glucosidase inhibitory activity to determine the antidiabetic activity showed that LEGI exhibited the inhibition on α-glucosidase activity with IC50 of 0.34 mg/mL, which was less potent than Acarbose (IC50 of 0.20 mg/mL). Assay of 2,2-diphenyl-2-picrylhydrazyl- hydrate (DPPH) radical scavenging to examine antioxidant activity revealed that LEGI demonstrated less potent DPPH scavenging activity compared to Butylated hydroxytoluene, BHT with IC50 of 0.43 vs 0.36 mg/mL, respectively. These results indicate that the leaf extract from G. inodorum possesses anti-inflamatory, antidiabetic and antioxidant activities that can be developed and used as natural agents for the tréamatent of diseases related to these activities. HIGHLIGHTS Using GC-MS analysis, there are 83 phytochemicals identified with 5 main compounds i.e. Phytol, n-Hexadecanoic acid, 9,12-Octadecadienoic acid (Z,Z)-, 9,12,15-Octadecatrienoic acid, (Z,Z,Z)- and Betulin, and 78 trace compounds in the ethanol leaf extract from Gymnema inodorum, and Phytol is the most predominant compound The extract can inhibit nitric oxide (NO) production, indicating its anti-inflammatory property The extract displays the inhibitory effect on α-Glucosidase activity, suggesting that the extract can be applied for antidiabetic management The extract possesses antioxidant property as evidenced by scavenging DPPH free radicals The extract shows low cytotoxicity to RAW 264.7 macrophages with IC50 of 128.77±2.82 µg/ml, by MTT assay GRAPHICAL ABSTRACT