Phytochemical Compositions and In vitro Assessments of Antioxidant and Antidiabetic Potentials of Fractions from Ehretia cymosa Thonn.

BACKGROUND: Ehretia cymosa Thonn. is a popular medicinal plant used in different parts of West Africa for the treatment of various ailments including diabetes mellitus. OBJECTIVE: The current study investigates bioactive constituents and in vitro antioxidant and antidiabetic potentials of fractions from extract of E. cymosa. MATERIALS AND METHODS: Phytochemical investigation and antioxidant assays were carried out using standard procedures. Antidiabetic potential was assessed by evaluating the inhibitory effects of the fractions on the activities of α-amylase and α-glucosidase, while bioactive constituent's identification was carried out using gas chromatography-mass spectrometric (GC-MS) analysis. RESULTS: The phytochemistry tests of the fractions revealed the presence of tannins, phenols, flavonoids, steroids, terpene, alkaloid, and cardiac glycosides. Methanol fraction shows higher phenolic (27.44 mg gallic acid/g) and flavonoid (235.31 mg quercetin/g) contents, while ethyl acetate fraction revealed higher proanthocyanidins (28.31 mg catechin/g). Methanol fraction displayed higher (P < 0.05) 1,1-diphenyl-2-picryl-hydrazyl (0.47 mg/mL), 2,2-azino-bis (3-ethylbenzothiazoline)-6-sulfonic acid (0.49 mg/mL), and hydroxyl radical (0.55 mg/mL) scavenging activities, while ethyl acetate exhibited strong metal chelating (0.61 mg/mL) and superoxide anion (1.68 mg/mL) scavenging activity. Methanol and ethyl acetate fractions displayed higher inhibition (P < 0.05) against α-glucosidase (0.60 mg/mL) and α-amylase (2.11 mg/mL), respectively. Methanol fraction also inhibited α-amylase and α-glucosidase in competitive and noncompetitive modes, respectively. The GC-MS chromatogram of the methanol fraction revealed 24 compounds, which include phytol (1.78%), stearic acid (1.02%), and 2-hexadecyloxirane (34.18%), which are known antidiabetic and antioxidant agents. CONCLUSION: The results indicate E. cymosa leaves as source of active phytochemicals with therapeutic potentials in the management of diabetes. SUMMARY: E. cymosa fractions possess antioxidant and antidiabetic activities. Hence, it is a source of active phytochemicals with therapeutic potentials in the management of diabetes. The high flavonoid, phenolic, and proanthocyanidin contents of fractions from E. cymosa also contribute to its antioxidant and antidiabetic properties. Methanol fraction of E. cymosa displayed better antidiabetic activities compared to acarbose as revealed by their half maximal inhibitory concentration values. Methanol fraction of E. cymosa extract contains phytol, hexadecyl oxirane, and stearic acid, which are reported to possess antidiabetic and antioxidant potentials. [Image: see text] Abbreviations used: ABTS: 2,2- Azino-bis (3-ethylbenzothiazoline)-6-sulfonic acid, DPPH: 1,1-diphenyl-2-picryl-hydrazyl, PMS: Phenazine methosulfate, NBT: Nitroblue tetrazolium, NADH: Nicotinamide adenine dinucleotide, TCA: Trichloroacetic acid, TBA: Thiobarbituric acid, DNS: Dinitrosalicylic acid.