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

BACKGROUND

There is paucity of information in literature on the natural products in cocoyam [Colocasia esculenta Linn (Araceae)] that confer it with biological properties.

OBJECTIVE

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.

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.

CONCLUSIONS

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.