Pharmacological and Antioxidant Properties of a Hydromethanol Extract of Dioscorea Bulbifera (Air Potato)
Nwoke, U. D.
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Dioscorea bulbifera is one of the over 600 known species of yam and is distinguished from all other species by having specialized aerial bulbils on the base of petioles. This work investigated some pharmacological and antioxidant properties of this endemic but neglected yam specie. In the study, the extract was assessed for proximate content, phytochemical content, free-radical scavenging, antioxidant potentials and antisickling effects. The proximate and the phytochemical constitution were performed according to standard analytical procedures available in the literature. In vitro antioxidant activity was studied through nitric oxide radical, hydroxyl radical, DPPH radical scavenging ability and reducing power assay. Furthermore, the antisickling effects of the extract were also studied based on its ability to inhibit haemoglobin polymerization of sickle cell erythrocytes. The results of the proximate analysis showed, moisture content (12.10 ± 0.61%), ash (12.00 ± 0.68%), crude fibre (1.50 ± 0.08%), crude protein (10.10 ± 0.53%), crude fat (1.20 ± 0.06%) and carbohydrate (63.10 ± 4.12%). Quantitative phytochemical study showed the presence of alkaloids (3.30 ± 0.13%), saponins (0.50 ± 0.02%), total glycosides (0.80 ± 0.03%), tannins (0.17 ± 0.01%), flavonoids (0.05 ± 0.04%) and phenolics (0.03 ± 0.10%). Moreso, D. bulbifera extract was effective against nitric oxide radical, hydroxyl radical, DPPH radical scavenging with potential inhibitory concentration (IC50) values of 1257.01 ± 58.37 (µg/ml), 633.60 ± 54.52 (µg/ml), 2285.78 ± 245.20 (µg/ml) respectively. The O.D0.5 of the extract was 480.63 ± 33.82 (µg/ml). Moreso, the extract showed the highest level of inhibition of haemoglobin HbS polymerization at 15.84 ± 0.74%. The results of this work showed that D. bulbifera is a good source of essential nutrients and can be a reliable food source and energy security crops to both man and/or livestock.The phytochemicals present could be the reason behind its medicinal uses. Results obtained also showed the ability of the extract to scavenge free radicals in dose-dependent manner. It therefore had good antioxidant properties. The extract also inhibited haemoglobin polymerization to a varying degree with good inhibition percent polymerization when compared to standard HBA. The extract therefore could be used for the treatment of oxidative stress induced diseases, management of sickle cell disease and other related diseases.