Highlights in BioScience ISSN: 2682-4043 DOI:10.36462/H.BioSci.20216 Highlights in BioScience August 2020| Volume 3 http://bioscience.highlightsin.org/ Page 1 of 7 Research Article Open Access 1 Department of Biological Sciences, Wesley University Ondo, Nigeria 2 Department_of_Biochemistry,_Federal University of Technology Akure, Nigeria Contacts of Authors * To whom correspondence should be addressed: Oluwasegun Victor Omotoyinbo Citation: Omotoyinbo OV, Awojulu EO and Sanni DM (2020). Phytochemical screening, antioxidant and tyrosinase inhibitory studies of methanol leaf extracts of two tomato varieties. Highlights in BioScience Volume 3. Article ID 20216. dio:10.36462/H.BioSci.20216 Received: June 8, 2020 Accepted: July 18, 2020 Published: August 18, 2020 Copyright: © 2020 Omotoyinbo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and supplementary materials Funding: The authors have no support or funding to report. Competing interests: The authors declare that they have no competing interests. Phytochemical screening, antioxidant and tyrosinase inhibitory studies of methanol leaf extracts of two tomato varieties Oluwasegun Victor Omotoyinbo 1 , Emmanuel Olumide Awojulu 2 and David Morakinyo Sanni 2 * 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 IC 50 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. Keywords: Tyrosinase, Inhibition, kinetics, phytochemicals, antioxidants, Lycopersicon esculentum. Introduction Tyrosinase (EC 1.14.18.1) is a metalloenzyme that catalyzes the rate- limiting reactions that are important to melanogenesis. It is classified as an oxidase and involves two distinct reactions, the hydroxylation of a monophenol, and conversion of an o-diphenol to the corresponding o-quinone. The oxidative polymerization of dopaquinone derivatives gives rise to melanin [1]. Melanin is a biopolymer synthesized by melanocyte, within specialized organelles called melanosomes. It is important to prevent UV-induced skin damage by absorbing UV sunlight and removing reactive oxygen species [2]. Although tyrosinase is a relatively important enzyme, abnormal biosynthesis or distribution of melanin may result in several dermatological disorders, such as age-spots, lentigines,