ABSTRACT

Methanolic and ethanolic extracts of Moringaoleifera leaves, seeds, roots and Piperguineense (Uziza) leaves were evaluated for antioxidant activity assayed by Total Phenol Content (TPC),1,1 -diphenyl - 2 - picrylhydrazyl (DPPH), 2, 2 – azino – bis 3 –ethyl benthiazoline-6-acid (ABTS), Total Antioxidant Capacity (TAC) and reducing power invitro. Gallic acid was used as standard in total phenol assay. Trolox equivalent was used as standard in ABTS, while ascorbic acid was used in reducing power, DPPH and total antioxidant capacity assays. The antioxidant activity of the extracts ranged from 2.13 to 16.64 µg/g for TPC, 0.24 to 0.89 mg/mL for DPPH, 5.66 to 10.09 µg/mL for ABTS, 3.24 to 6.48 µg/mL for reducing power and 9.76 to 53.25µg/mL for TAC. The highest valueranged from 9.76 ascorbic acid equivalent (AAE) µg/mL in Piper hhhguineense leaf to 53.25 AAE µg/mL in moringa seed while DPPH content was the lowest and ranged from 0.24 mg/mL in Piper guineense leaf to 0.89mg/mL inmoringa seed. In the TPC, moringa leaf extract had the highest value of 16.64 µg/g while the seed extract exhibited the least value of 2.13 µg/g. Also, moringa seed extract had the highest value of 0.89 mg/mL in DPPH and the least value 0.24 mg/mL seen in Piper guineense leaf extract. Piper guineense leaf had the greatest activity since lower values indicate higher activity. The root extract of moringa had the highest value of 10.09µg/mL in ABTS while Piper guineenseleaf extract had the least value of 5.66µg/mL. In the reducing power, the highest value (6.48 µg/mL)observed in moringa leaf while Piper guineense leaf had the least value of 3.24µg/mL. Moringaseed extract had the highest value of 53.25µg/mL in the total antioxidant capacity while Piper guineense seed extract exhibited the least activity. The proximate composition of the extracts ranged from 5.12 to 12.16%, 5.58 to 12.60%, 4.31 to 10.47%, 13.91 to 25.05%, 0.05 to 3.30% and 40.59 to 68.39% for moisture, ash, fibre, protein, lipid and carbohydrate content respectively. Piper guineense leaf extract had the highest moisture content of 12.16% while moringa seed had the least with value 5.12%. Moringa leaf extract exhibited the highest value in ash and fibre content with values of 12.60% and 10.4% respectively. Meanwhile moringa seed extract had the highest carbohydrate content of 68.39 %. In terms of the mineral and vitamin content, the extract of moringa leaf exhibited the highest value in potassium and magnesium content with values of 63.23 mg/100g and 57.01 mg/100g respectively while Piper guineense leaf had the highest value of 48.18mg/100g for calcium. The extract of Piper guineense leaf showed the highest value in β – carotene (pro-vitamin A)and vitamin C content with values 3.14 mg/100g and 134.34 mg/100g respectively. There was significant (p< 0.05) difference in the proximate composition except for moisture content were there was no significant (p> 0.05) difference between two samples, minerals and vitamin contents of moringa leaf, the seed, the root and Piperguineense leaf extracts. From this analysis therefore, moringa leaf and Piperguineense leaf could serve as prospective source of natural antioxidants to food and health industries.