Characterization of the natural products in cocoyam (Colocasia esculenta) using GC–MS

Abstract

Context: There is paucity of information in literature on the natural products in cocoyam [Colocasia esculenta Linn (Araceae)] that confer it with biological properties.Objectives: This study investigated the antioxidant properties of C. esculenta and also reported for the first time the natural products in C. esculenta that justify its biological properties.Materials and methods: The antioxidant activity of the methanol extract (50–250 μg/mL) of C. esculenta was determined using the 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical and reducing power assays. Characterization of the natural products in C. esculenta was done using the gas chromatographic–mass spectrometric (GC–MS) technique. The experiment lasted for 3 months.Results: GC–MS analysis of methanol/chloroform extract of the flour of C. esculenta indicated the presence of eight compounds, namely hexadecanoic acid methyl ester (0.43%), octadecanoic acid (20.91%), 9,12-octadecadienoyl chloride (0.77%), 11-octadecenoic acid methyl ester (2.12%), 9-octadecenoic acid (64.37%), 3-hexadecyloxycarbonyl-5-(2-hydroxylethyl)-4-methylimidazolium(1.36%), hexanedioic acid, bis(2-ethylhexyl)ester (1.36%) and 3,5-di-t-butyl phenol (3.27%). The total phenolic content of C. esculenta was 15.15 ± 0.35 mg Gallic Acid Equivalence/g and it was significantly higher (p < 0.05) than the total flavonoid (8.50 ± 0.42 mg Quercetin Equivalence/g) and condensed tannin (4.40 ± 0.14 mg Catechin Equivalence/g) contents, respectively. C. esculenta possessed strong antioxidant capacity though it was lower than that of standard quercetin.Discussion and conclusion: Results showed that C. esculenta possesses strong antioxidant activity and also contains some important bioactive compounds that justify its medicinal properties as used in ethno-medicine.