Tyrosinase plays a pivotal role in the synthesis of melanin pigment synthesis on skin utilizing tyrosine as a substrate. Melanin is responsible for the protection against harmful ultraviolet irradiation, which can cause significant pathological conditions, such as skin cancers. However, it can also create esthetic problems when accumulated as hyperpigmented spots. Various skin-whitening ingredients which inhibit tyrosinase activity have been identified. Some of them, especially ones with natural product origins, possess phenolic moiety and have been employed in cosmetic products. Semi-synthetic and synthetic inhibitors have also been developed under inspiration of the natural inhibitors yet some of which have no phenolic groups. In this review, tyrosinase inhibitors with natural, semi-synthetic and synthetic origins are listed up with their structures, activities and characteristics. Further, a recent report on the adverse effect of a natural melanin synthesis inhibitor which was included in skin-whitening cosmetics is also briefly discussed.

https://www.tandfonline.com/doi/pdf/10.3109/14756366.2015.1004058

Natural, semisynthetic and synthetic tyrosinase inhibitors

Pyranocycloartobiloxanthone A, a novel gastroprotective compound from Artocarpus obtusus Jarret, against ethanol-induced acute gastric ulcer in vivo

Tyrosinase (EC 1.14.18.1), also known as polyphenols oxidase, is a glycosylated multi-copper monooxygenase enzyme widely distributed in many different organisms. The enzyme is responsible for the pigmentation of skin, eyes and hair in mammals and in fruits and vegetables undesired browning. These issues have encouraged researchers all over the world to seek new, potent and safe inhibitors of the enzyme for use in foods and cosmetics. A large number of compounds from natural products have been reported as moderate to potent inhibitors of tyrosinase. Among them, many flavonoid derivatives have been revealed to be the strong inhibitors of tyrosinase. In this review, we reviewed many examples of tyrosinase inhibitors with flavonoid structure reported between 2008-2013. Our findings underline that flavonoids should continue to be the focus of tyrosinase inhibition studies as the promising compounds.

Flavonoid derivatives as potent tyrosinase inhibitors - a survey of recent findings between 2008-2013.

New antibacterial xanthone from the marine sponge-derived Micrococcus sp. EG45

Herbs and spices have been used in retaining and boosting human beauty since time immemorial. Herbal cosmetic has growing demand in the worldwide market and is an invaluable gift of Mother Nature. In the present review, the focus is on the cosmetic herbs of Southeast Asian countries namely Malaysia, Cambodia, Laos, Myanmar [Burma], Thailand, Vietnam, Brunei, East Timor, Indonesia, Philippines and Singapore in highlighting both traditional and scientific knowledge or background of the selected potential herbs. The available literature was searched in the following scientific database such as PubMed, Google Scholar, Science Direct and Springer for publications and patents. In view of traditional uses, herbs like Allium sativum, Aloe vera, Centella asiatica, Curcuma longa, Hibiscus rosa-sinensis, Lawsonia inermis and Tamarindus indica L. were classified as need of special mention. Many herbs have been scientifically evaluated for their cosmetic potentials such as anti-aging, anti-acne, melanogenic and anti-tyrosinase activities. The great void remains for a systematic study, thorough review of scientific report that provides a basis for the use of specific herbs due to their efficacy as cosmetics. In addition, two of the Malay herbs; Labisia pumila (Kacip Fatimah) and Ficus deltoidea (Mas cotek), are proposed to be clinically studied for their safety in cosmetic application aspects wherein the need for safety evaluation and fruitful application of herbal cosmetics were emphasized.

Cosmetic potential of Southeast Asian herbs: an overview

One of the most promising plants in biological screening test results of thirteen Artocarpus species was Artocarpus obtusus FM Jarrett and detailed phytochemical investigation of powdered dried bark of the plant has led to the isolation and identification of three xanthones; pyranocycloartobiloxanthone A (1), dihydroartoindonesianin C (2) and pyranocycloartobiloxanthone B (3). These compounds were screened for antioxidant, antimicrobial and tyrosinase inhibitory activities. Pyranocycloartobiloxanthone A (1) exhibited a strong free radical scavenger towards DPPH free radicals with IC50 value of 2 µg/mL with prominent discoloration observed in comparison with standard ascorbic acid, α-tocopherol and quercetin, The compound also exhibited antibacterial activity against methicillin resistant Staphylococcus aureus (ATCC3359) and Bacillus subtilis (clinically isolated) with inhibition zone of 20 and 12 mm, respectively. However the other two xanthones were found to be inactive. For the tyrosinase inhibitory activity, again compound (1) displayed strong activity comparable with the standard kojic acid.

https://www.mdpi.com/1420-3049/17/5/6071/pdf

Muhamad Aizat Mohd Amin

Papers

Antioxidant, Antimicrobial and Tyrosinase Inhibitory Activities of Xanthones Isolated from Artocarpus obtusus F.M. Jarrett