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Tyrosinase is a key enzyme in melanogenesis. Its high activity is associated with increased pigmentation causing skin disorders like freckles, melasma and black spots. Therefore, search for new tyrosinase inhibitors is desirable. In present study, methanolic (MeOH) extracts from leaves, fruit peel and pulp of Citrus bergamia (C. bergamia) and, leaves and fruit of Ficus carica (F. carica) were prepared which were further processed for fractional distillation using ethyl acetate (EA), n-hexane (n-Hx) and chloroform (CHCl3) preparing total 20 extracts aiming to test their anti-tyrosinase potential, in-vitro. Our results confirmed that all C. bergamia and F. carica crude extracts showed significant anti-oxidant activity with IC50 range of 384.2 ± 19.1 to 77.3 ± 10.0 µgmL-1, collectively. Moreover, significant anti-tyrosinase activity for C. bergamia (IC50 range = 4.1 ± 0.3 to 366.8 ± 36.5 µg mL-1) and F. carica (IC50 range = 156.5 ± 12.4 to 15.1 ± 2.9 µg mL-1) was found. Interestingly, C. bergamia MeOH-EA peel and C. bergamia MeOH-EA leaves extracts showed IC50 4.1 ± 0.3 and 6.1 ± 1.2 µg mL-1, respectively. Thus, C. bergamia MeOH-EA peel extract with lowest IC50 value among all the tested extracts, is proposed as potent candidate to control tyrosinase rooted hyperpigmentation in future. [ABSTRACT FROM AUTHOR]

Present study was conducted at the Department of zoology at Mirpur University of Science and Technology (MUST), during 2018-2019 to isolate extracts from selected plants (Garlic and Peppermint) to explore their tyrosinase inhibition activity. Tyrosinase is a key enzyme of melanogenesis which determines the mammalian skin, hair and eye colour. Hyper-pigmentation leads to various skin disorders like melasma, sunspots, age spots and freckles. Moreover, abnormal skin pigmentation is a serious aesthetic concern which leads to psychosocial problems. Thus to achieve melanin inhibition, inhibition of tyrosinase might be an effective approach. To this end we prepared methanolic (MeOH) extracts from leaves and roots of Garlic Allium sativum (AS) and Peppermint Mentha piperita (MP), which were further processed for 1:1 fractional distillation to prepare methanolic n-hexane (MeOH_n-Hx), methanolic ethyl acetate (MeOH_EA) and methanolic chloroform (MeOH_CHCl3) extracts, aiming to evaluate tyrosinase and antioxidant activities in-vitro. Our results confirmed that all MeOH-crude AS and MP extracts showed significant anti-oxidant activity with IC50 values ranging from 0.05 ± 0.2 mg/ml to 4.3 ± 2.³mg/ml. Moreover, AS and MP all 16 extracts have significant anti-tyrosinase activity with IC50 range from 0.014 ± 0mg/ml to 1.205 ± 0.07mg/ml. Interestingly, AS leaf MetOH_EA, AS leaf MetOH_CHCl3, AS root MetOH_EA and MP leaf MetOH_CHCl3 showed significant anti-tyrosinase activity even higher than positive control kojic acid. AS leaf MetOH_CHCl3 extract being the most potent among all tested extracts is proposed as potential candidate to treat tyrosinase rooted hyper-pigmentation in future. [ABSTRACT FROM AUTHOR]

In this review, specific therapeutic and medicinal advantages including antiviral, antibacterial, antifungal and antitumor, strategies for drug designing, structure-activity relationship, advances in the syntheses of azo and hippuric acid derivatives of more than 50 compounds have been discussed since 2009-2018. It is found that phenyl-diazenyl azo derivatives and pyridinyl substituted hippuric acid derivatives showed promising antiretroviral potential. The incorporation of azo functionality to the respective quinolones and coumarin moieties and the insertion of thiocarbazone to hippuric acid displayed immense antibacterial activities. While, azo and hippuric acid derivatives of triazole and phenyl species gave maximum fungicidal as well as cytotoxic activities., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)