Formulation and antioxidant characterization of nutraceutical extracts from fruits, fruit peels, seeds and vegetables commonly available in Kaduna State, northern Nigeria

Antioxidants are compounds in fruits, vegetables and spices capable of preventing free radical-induced chronic diseases such as diabetes, hypertension, obesity, cancer, neurodegeneration and cardiovascular diseases. The peels and seeds of fruits have found applications as sources of medicine for various ailments in traditional medicine. This study evaluated selected phytochemicals and antioxidant activities in some fruits, fruit peels, seeds, vegetables and spices. Standard methods were used to determine the phenolic compounds, flavonoids, tannins and alkaloids in the aqueous extracts of the tested samples. Antioxidant activities (DPPH and NO scavenging) were assayed by spectroscopy. All the extracts tested have varying concentrations of selected phytochemicals. The antioxidant activity of the extracts in respect to DPPH radical and nitric oxide scavenging ranged from moderate to good antioxidant activity (IC50 9 – 70 µg/mL). Tamarindus indica nutraceutical extracts exhibited a high degree of antioxidant activity (IC50 value of 9.17 µg/mL and 80.80 ± 0.28 % DPPH inhibition), and recorded high total flavonoid contents (72.79 ± 0.34mg/g QE) than all the tested extracts. Mixtures of samples used to formulate nutraceutical extracts indicated some degree of radical scavenging activities in the order: TGT > Ascorbic acid > AvoG > POG > DGT > BSG > T-refresh > P-refresh for DPPH and T-refresh > P-refresh > DGT > Ascorbic acid > POG > BSG > TGT > AvoG for NO scavenging activities in the tested extracts. Further study to optimize extraction and nutraceutical potency with respect to other physiochemical properties of nutraceutical agents is recommended.