Phytochemical screening, antioxidant and tyrosinase inhibitory studies of methanol leaf extracts of two tomato varieties

Abstract

This study evaluated the phytochemical compositions, antioxidant properties, chlorophyll content and anti-tyrosinase activity of methanol leaf extracts of two tomato varieties, Lycopersicon esculentum (var. Eva F1) and Lycopersicon esculentum Mill (var. Hausa). The dried pulverized of the plant’s leaves were extracted by decoction and mild agitation. Phytochemicals such as flavonoids, tannin, glycoside, saponin, terpenoid and anthraquinone were present in the extracts of both varieties examined, while alkaloid and phlobatannin were confirmed absent in the extracts. The presence of steroid was observed in var. Eva F1 but absent in var. Hausa. Total phenolic content (TPC) and total flavonoid content (TFC) of var. Eva F1 were 505.9 ± 2.61 mg GAE/ge, and 35.5 ± 1.64 mg RE/ge, while var. Hausa recorded a TPC and TFC value of 344.3 ± 2.01 and 7.8 ± 0.15 mg RE/ge respectively. The chlorophyll content of the extracts were 6.6 ± 0.02 mg/ge (chlorophyll a), 5.7 ± 0.05 mg/ge (chlorophyll b) and 12.6 ± 0.14 mg/ge (total chlorophyll content) for Eva F1 variety, while the chlorophyll contents for var. Hausa were 7.6 ± 0.32 mg.ge (chlorophyll a), 5.6 ± 0.06 mg/ge (chlorophyll b) and 13.7 ± 0.14 mg/ge. Eva F1 and Hausa showed percentage inhibition of 76.3 % and 61.2 % at 400 μg/mL. The IC₅₀ value of var. Eva F1 and var. Hausa were 110 μg/mL and 160 μg/mL. The inhibition constant (K_I) of var. Eva F1 and var. Hausa, were 0.006 and 0.016 μg/mL, respectively, and both extracts showed partial competitive inhibition. Hence, this confirms the phytoprotective and tyrosinase inhibitory properties of tomato plant leaves.