Antioxidant and Tyrosinase Inhibiting Activities of Ethylacetate, Methanolic and Aqueous Extracts of Basella alba Leaves

Basella alba is a leafy green plant commonly cultivated and consumed as vegetable in many Asian and tropical African communities. The plant has been scientifically proven to possess a number of beneficial effects including antioxidant effect. This study was aimed at investigating comparatively, the flavonoids content, the antioxidant and antityrosinase activities of ethylacetate, methanol and aqueous extract of Basella alba leaves and establish a possible relationship among these parameters. Two flavonoids, namely flavanol and flavonol were quantitatively measured in the extracts and antioxidant capacities assessed using TEAC, ORAC and FRAP assays. The result showed that ethylacetate extract contains much higher concentrations of flavanol and flavonol when compared to both methanol and aqueous extracts which contain negligible amounts of the two flavonoids. Values of antioxidant capacities were as follows; Aqueous (TEAC = 439.90 ± 0.07 µmol TE/g, ORAC =1384.40 ± 90.65 µmol TE/g, FRAP = 48.17 ± 0.00 µmol AAE/g ), ethylacetate (TEAC = 61.30 ± 0.07 µmol TE/g, ORAC =483.09 ± 35.00 µmol TE/g, FRAP = 117.99 ± 0.01 µmol AAE/g) and methanol (TEAC = 44.20 ± 0.03 µmol TE/g, ORAC = 1286.25 ± 9.00 µmol TE/g, FRAP = 46.64 ± 0.00 µmol AAE/g). All three extracts had inhibitory activity against tyrosinase at effective concentrations of 193.58 ± 0.02, 203.33 ± 0.02 and 222.83 ± 0.03 µg/mL for aqueous, methanol and ethylacetate extracts respectively. It was concluded from the results that the aqueous extract of Basella alba leaves produced the best antioxidant and antityrosinase activities and the two actions may be directly related.