Evaluation of antioxidant, anti-tyrosinase potentials and phytochemical composition of four Egyptian plants

The aim of this present research is to evaluate antioxidant and antityrosinase potentials and to investigate the phytoconstituents of methanol (70%) extract from four Egyptian plants, Solanum rantonnetii, Tilia cordata, Cichorium intybus (L.), and Lagerstroemia tomentosa. Antioxidant activity was measured by using two different free radical scavenging methods, 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•), whereas polyphenols and flavonoids contents were evaluated by using Folin-Ciocalteau, and aluminum nitrate methods respectively. Tyrosinase inhibition was evaluated using commercial enzyme and dihydroxyphenylalanine (DOPA) as substrate and methanol extract of each plant was investigated by phytochemical analysis. The results showed that all the plants had good antioxidant activity where Cichorium intybus exhibited the highest antioxidant activity determined as total content of free-radical scavenging, polyphenol and flavonoid molecules, and showed the best tyrosinase inhibition activity compared with the other plants extracts studied. Chromatogarphic separation and NMR analysis of Cichorium intybus methanol extract revealed the identification of two coumarins, scopoletin and esculetin, and seven flavonoids, dihydroquercetin 7-4'-dimethyl ether, blumeatin, diosmetin, tamarixetin, quercetin, quercetin 3-O-β-galactoside and kaempferol 3-O-rutinoside. These findings suggest that Cichorium intybus is rich with bioactive compounds and could be used as a good source of potentially natural antioxidants and antityrosinase molecules.