Barbarin as a New Tyrosinase Inhibitor from Barbarea orthocerus

Abstract

A tyrosinase inhibitor was isolated from the whole plant of Barbarea orthocerus Led. (Brassicaceae) by activity-guided fractionation, and identified as (R)-5-phenyl-2-oxazolidinethione (barbarin) by structural analysis followed by comparison with reported spectral data. The compound exhibited significant inhibitory effects on mushroom and murine tyrosinases at more than 1.6 x 10(-5) M. Barbarin exhibited IC50 values of 4.2 x 10(-5) M on mushroom tyrosinase and of 4.8 x 10(-5) M on murine tyrosinase. Kojic acid as a positive control exhibited IC50 values of 3.4 x 10(-5) M and 6.0 x 10(-5) M on mushroom and murine tyrosinases, respectively. Therefore, barbarin exhibited a similar level of inhibitory potency with kojic acid used as a positive control. In a kinetic study with various concentrations of L-dopa as the substrate, barbarin was identified as an uncompetitive inhibitor and kojic acid as a mixed inhibitor of both mushroom and murine tyrosinases. Barbarin exhibited KEIS values of 3.3 x 10(-5) M and 3.6 x 10(-5) M on mushroom and murine tyrosinases, respectively. Kojic acid exhibited KEIS and KEI values of 2.4 x 10(-5) M and 2.2 x 10(-5) M on mushroom tyrosinase and those of 8.9 x 10(-5) M and 7.2 x 10(-5) M on murine tyrosinase, respectively.

Oxyresveratrol and Hydroxystilbene Compounds

“…Tyrosinase is also responsible for the undesired enzymatic browning of food products originating from plant and crustacean that takes place during postharvest handling, which causes a decrease in market value (19 -21). Therefore, novel tyrosinase inhibitors are of great concern to food technologists and processors (22)(23)(24).In animals, melanin pigments are produced by melanocytes and deposited throughout the epidermis, which is the determinant of skin color (25-28). However, disturbances in the amount and distribution of melanin pigments might ultimately provide clues to several diseases.…”

Whitening Agents from Reseda luteola L. and Their Chemical Characterization Using Combination of CPC, UPLC-HRMS and NMR

“…If the R. luteola anti-inflammatory and anti-oxidant activities, mainly credited to its luteolin content, have already been discussed [20], to our knowledge, the literature only alludes to its skin whitening briefly. In fact, R. luteola, like other species from the order Brassicales, contains glucosinolates (sulfur-and nitrogen-containing secondary metabolites) and notably glucobarbarin, the hydrolysis of which leads to barbarin (= (R)-5-phenyl-2-oxazolidinethione), which is identified as a potent inhibitor of mushroom and murine tyrosinases [21,22]. The objective of this work was hence to assess whether barbarin or other compounds yet to identify, are responsible for the whitening activity of R. luteola extracts.…”

“…The HPLC fingerprinting of this extract revealed the presence of two groups of components: a series of flavonoid derivatives eluting between 6 and 19 min and a series of highly apolar compounds eluting between 42 and 58 min ( Figure 1). and murine tyrosinases [21,22]. The objective of this work was hence to assess whether barbarin or other compounds yet to identify, are responsible for the whitening activity of R. luteola extracts.…”

Glucosinolate hydrolysis products in the crucifer Barbarea vulgaris include a thiazolidine-2-one from a specific phenolic isomer as well as oxazolidine-2-thiones

“…A general effect of OATs can be disturbance of certain redox reactions, similar to the known OAT disturbance of iodine metabolism in the mammalian thyroid gland (Bille et al, 1983;Vanderpas, 2006). Interference with a specific enzyme reaction in melanin biosynthesis, tyrosinase (EC 1.14.18.1), has also been reported (Seo et al, 1999), but has not been linked to toxic effects. Finally, with the identification of the product of 3 as a thiazolidine-2-one (TAO) (Fig.…”