Potent Tyrosinase Inhibitors Research Articles

Synthesis and evaluation of bibenzyl glycosides as potent tyrosinase inhibitors

Bibenzyl glycosides 1– 6 were synthesized from 2,4-dihydoxybenzaldehyde and xylose, glucose, cellobiose or maltose. The key steps in the synthesis were the Wittig reaction and trichloroacetimidate glycosylation. Tests for tyrosinase inhibitory activity showed that all were significantly active, indicating that they are unique hydrophilic tyrosinase inhibitors. Bibenzyl xyloside 2 is a particularly potent inhibitor (IC 50 = 0.43 μM, 17 times higher than that of kojic acid). These results suggest that the hydrophilic cavity of tyrosinase might accommodate the bulky carbohydrate on the bibenzyl scaffold.

Synthesis and biological activity of hydroxybenzylidenyl pyrrolidine-2,5-dione derivatives as new potent inhibitors of tyrosinase

In this study, we describe the synthesis and tyrosinase inhibitory activity of a new family of hydroxybenzylidenyl pyrrolidine-2,5-dione compounds. Among them, compound 3f (HMP) exhibited the highest inhibition, 83.87%, at a concentration of 20 μM, on the L-DOPA oxidase activity of mushroom tyrosinase. We also predicted the tertiary structure of tyrosinase, simulated its docking with HMP and confirmed that HMP strongly interacts with tyrosinase residues. This result suggested that the binding activity of HMP with tyrosinase could be high. Based on these results, we determined the IC50 value for HMP inhibition of mushroom tyrosinase activity. HMP inhibited mushroom tyrosinase with an IC50 value of 2.23 ± 0.44 μM, which is more potent than the anti-tyrosinase activity of kojic acid (IC50 = 20.99 ± 1.80 μM), a well-known tyrosinase inhibitor. Kinetic analysis of tyrosinase inhibition revealed that HMP is a competitive inhibitor (Ki = 4.24 × 10−7 M at 1.25 μM and Ki = 1.82 × 10−6 M at 20 μM). HMP also inhibited melanin production and tyrosinase activity in B16F10 melanoma cells (B16 cells). These data strongly suggest that HMP can suppress the production of melaninvia the modulation of tyrosinase activity.

Surface modification for small-molecule microarrays and its application to the discovery of a tyrosinase inhibitor

Small-molecule microarrays are powerful, high-throughput tools for gathering information about direct binding events between proteins of interest and small molecules. However, nonspecific binding on modified glass slides is the major factor reducing the quality of information obtained in proteomic screening with small-molecule microarrays. To improve the signal-to-noise ratio by suppressing the background signal, we tested several surface modification methods for glass slides. Jeffamine-coated slides showed a high fluorescence signal and a significantly enhanced signal-to-noise ratio. We applied this surface modification to proteomic screening of potential tyrosinase inhibitors with a small-molecule microarray and identified 2,4,4'-trihydroxychalcone as a new small-molecule binder to tyrosinase. Its actual binding and inhibitory effects on tyrosinase were validated using an SPR binding assay and an enzyme-based inhibition assay, respectively. Thus, we successfully demonstrate the application of Jeffamine-based modification to proteomics screening with small-molecule microarrays.

2-Phenyl-1,4-benzopyrone 유도체 (Flavones)의 Tyrosinase 저해활성에 관한 3D-QSARs 분석과 분자도킹

기질분자로서 polyhydroxy 치환된 2-phenyl-l,4-benzopyrone 유도체(Flavones)(1-25)들의 hydroxyl 치환기(<TEX>$R_1-R_9$</TEX>)가 변화함에 따른 Tyrosinase(PDB ID: oxy-form; 1WX2)에 대한 저해활성을 이해하기 위하여 분자도킹과 3차원적인 정량적 구조활성관계 (3D-QSARs: CoMFA 및 CoMSIA)가 연구되었다. 그 결과, 통계적으로 CoMFA 1 및 CoMSIA 1 모델이 가장 양호한 3D-QSARs 모델이었다. 또한, 순차 혼합화 분석결과로부터 CoMSIA 1 모델(<TEX>$dq^2'/dr_{yy'}^2$</TEX>=1.009 및 <TEX>$q^2$</TEX>=0.511)이 우연상관성에 저촉되지 않는 최적화 모텔이었으며 최적화된 CoMSIA 1 모델의 tyrosinase에 대한 저해활성은 기질분자의 정전기장(51.4%)에 의존적이었다. Tyrosinase의 반응점에 대한 3D-QSAR 모델의 등고도는 수용체로서 tyrosinase과 저해제로서 2-phenyl-l,4-benzopyrone 기질분자 사이의 새로운 상호작용 관계를 이해하는 계기가 되었다. 그러므로 이 결과들은 새로운 잠재적인 tyrosinase 저해제의 최적화에 적용될 수 있을 것이다. To understand the inhibitory activity with changing hydroxyl substituents (<TEX>$R_l-R_9$</TEX>) of polyhydroxy substituted 2-phenyl-l,4-benzopyrone analogues (1-25) against tyrosinase (PDB ID: oxy-form; 1WX2), molecular docking and the three dimensional quantitative structure-activity relationships (3D-QSARs: Comparative molecular field analysis (CoMFA) & Comparative molecular similarity indices analysis (CoMSIA)) were studied quantitatively. The statistically best models were CoMFA 1 and CoMSIA 1 model from the results. The optimized CoMSIA 1 model with the sensitivity of the perturbation and the prediction produced (<TEX>$dq^2'/dr_{yy'}^2$</TEX>=1.009 & <TEX>$q^2$</TEX>=0.51l) by a progressive scrambling analysis were not dependent on chance correlation. The inhibitory activities with optimized CoMSIA 1 model were dependent upon electrostatic factor (51.4%) of substrate molecules. Contour mapping the 3D-QSAR models to the active site of tyrosinase provides new insight into the interaction between tyrosinase as receptor and 2-phenyl-l,4-benzopyrone analogues as inhibitor. Therefore, the results will he able to apply to the optimization of a new potent tyrosinase inhibitors.

Synthesis and biological evaluation of polyhydroxy benzophenone as mushroom tyrosinase inhibitors

A series of polyhydroxy benzophenone were synthesized and evaluated as mushroom tyrosinase inhibitors. The results demonstrated that most of the target compounds had remarkable inhibitory activities on mushroom tyrosinase. Among all these compounds, 2,3,4,3′,4′,5′-hexahydroxy-diphenylketone 10 was found to be the most potent tyrosinase inhibitor with IC50 value of 1.4 μM. In addition, the inhibition kinetics analyzed by Lineweaver–Burk plots revealed that such compounds were competitive inhibitors. These results suggested that such compounds might be utilized for the development of new candidate for treatment of dermatological disorders.

Screening of marine algae for potential tyrosinase inhibitor: those inhibitors reduced tyrosinase activity and melanin synthesis in zebrafish.

In order to find new anti-browning and whitening agents in this study, we investigated 43 indigenous marine algae for tyrosinase inhibitory activity. The extracts from Endarachne binghamiae, Schizymenia dubyi, Ecklonia cava (EC) and Sargassum silquastrum (SS) evidenced potent tyrosinase inhibitory activity similar to that of positive control, kojic acid. Among those marine algae, EC and SS are distributed abundantly on Jeju Island. Therefore, we selected those two species for further studies. Our results evidenced that both species reduced cellular melanin synthesis and tyrosinase activity. On the other hand, we utilized zebrafish as an alternative in vivo model. All the tested samples evidenced excellent inhibitory effects on the pigmentation of zebrafish, most likely due to their potential tyrosinase inhibitory activity. In simultaneous in vivo toxicity tests, no toxicity was observed in either algal species, on the other hand, toxicity was observed in positive controls. These results provided that EC and SS extract could be used as an ingredient for whiting cosmetics and that zebrafish is an alternative in vivo model.

Synthesis and Structure−Activity Relationship Study of Deoxybenzoins on Relaxing Effects of Porcine Coronary Artery

Deoxybenzoins are potent antioxidants and tyrosinase inhibitors with potential to be developed as food preservatives and cosmetic ingredients. To explore the potential in cardiovascular protection, 25 polyphenolic deoxybenzoins were synthesized and evaluated for inhibitory effects on KCl-induced porcine coronary arterial contraction. The results revealed deoxybenzoins are significant inhibitors of KCl-induced arterial contraction. Among those synthesized, two-thirds of the deoxybenzoins exhibited moderate to good efficacy on relaxing contracted artery including 2,4-dihydroxydeoxybenzoin with EC50=3.30 μM (Emax=100%, n=7) and 2,4-dihydroxy-4'-methoxydeoxybenzoin EC50=3.70 μM (Emax=100%, n=5). Deoxybenzoins displayed an endothelium-dependent relaxing manner on the contracted artery; the contractile responses of neither endothelium denuded nor L-NAME deactivated rings were inhibited. The structure-activity relationships of deoxybenzoin on arterial relaxing effects concluded that the 2,4-dihydroxylated deoxybenzoins presented a potential vascular relaxing pharmacophore, with favoring substitution on ring B in the order of H≥p-OMe>p-OH>o-OMe>m,p-diOMe≥m-OMe.

Design and synthesis of biphenyl derivatives as mushroom tyrosinase inhibitors

Two new series of biphenyls, analogs of aglycone of natural product fortuneanoside E, were prepared using Suzuki–Miyaura cross-coupling and selective magnesium iodide demethylation/debenzylation, and their mushroom tyrosinase inhibitory activity was evaluated. Most of the 4-hydroxy-3,5-dimethoxyphenyl biphenyl compounds (series II, 20–36) were in general more active than 3,4,5-trimethoxyphenyl biphenyl compounds (series I, 1–19). Structure–activity relationships study showed that monosaccharide substituents, such as glucose, were not necessary and the presence of 4-hydroxy-3,5-dimethoxyphenyl moiety was crucial for inhibitory activity. Among the compounds synthesised, compound 21 (IC50=0.02mM) was found to be the most active one, which exhibited an activity that was 7 times higher than that of fortuneanoside E (IC50=0.14mM) and 10 times higher than that of arbutin (IC50=0.21mM), known as potent tyrosinase inhibitors. The inhibition kinetics analyzed by Lineweaver–Burk plots revealed that compound 21 was a competitive inhibitor (Ki=0.015mM).

New potent inhibitors of tyrosinase: Novel clues to binding of 1,3,4-thiadiazole-2(3H)-thiones, 1,3,4-oxadiazole-2(3H)-thiones, 4-amino-1,2,4-triazole-5(4H)-thiones, and substituted hydrazides to the dicopper active site

A series of 1,3,4-thiadiazole-2(3H)-thiones, 1,3,4-oxadiazole-2(3H)-thiones, 4-amino-1,2,4-triazole-5(4H)-thiones, and substituted hydrazides were tailored and synthesized as new potent inhibitors of tyrosinase. The rationale for inhibitor design was based on the active site structural evidence from the crystal structures of bacterial tyrosinase and potato catechol oxidase enzymes. Kinetic and active site binding studies suggested mono-dentate binding of thiadiazole, oxadiazole, and triazole rings to the active site dicopper center of tyrosinase including hydrophobicity contributing to the potent inhibition. Kinetic plots showed mixed-type of inhibition by all 25 compounds. Substitutions at C3 of the triazole ring and C5 of the thiadiazole/oxadiazole rings were found to be playing a major role in the high binding affinity to tyrosinase. The current work may help develop new potent tyrosinase inhibitors against hyperpigmentation including potential insecticides.

Natural ortho-dihydroxyisoflavone derivatives from aged Korean fermented soybean paste as potent tyrosinase and melanin formation inhibitors

Natural o-dihydroxyisoflavone (ODI) derivatives with variable hydroxyl substituent at the aromatic ring of isoflavone and three known isoflavones were isolated from five-year-old Korean fermented soybean paste ( Doenjang) and evaluated as potent inhibitors on tyrosinase activity and melanin formation in melan-a cells comparing with other known isoflavones, 7,8,4′-trihydroxyisoflavone ( 1) and 7,3′,4′-trihydroxyisoflavone ( 2) inhibited tyrosinase by 50% at a concentration of 11.21 ± 0.8 μM and 5.23 ± 0.6 μM (IC 50), respectively, whereas, 6,7,4′-trihydroxyisoflavone ( 3), daidzein ( 4), glycitein ( 5) and genistein ( 6) showed very low inhibition activity. Furthermore, those compounds significantly suppressed the cellular melanin formation by 50% at a concentration of 12.23 ± 0.7 μM ( 1), 7.83 ± 0.7 μM ( 2), and 57.83 ± 0.5( 6) and show more activity than arbutin. But, compounds 3, 4, and 5 showed lower inhibition activity. This study shows that the position of hydroxyl substituent at the aromatic ring of isoflavone plays an important role in the intracellular regulation of melanin formation in cell-based assay system.

Synthesis and biological evaluation of novel 4-hydroxybenzaldehyde derivatives as tyrosinase inhibitors

A series of novel 4-hydroxybenzaldehyde derivatives were synthesized and their inhibitory effects on the diphenolase activity of mushroom tyrosinase were investigated. Most of target compounds had more potent inhibitory activities than the parent compound 4-hydroxybenzaldehyde (IC50=1.22mM). Interestingly, compound 3c bearing a dimethoxyl phosphate was found to be the most potent inhibitor with IC50 value of 0.059mM. The inhibition kinetics analyzed by Lineweaver–Burk plots revealed that compound 3c was a non-competitive inhibitor (KI=0.0368mM). In particular, compound 3c showed no side effects at dose of 1600mg/kg in mice. These results suggested that such compounds might be served as lead compounds for further designing new potential tyrosinase inhibitors.

Tyrosinase inhibitory effect and inhibitory mechanism of tiliroside from raspberry

Tiliroside was found to inhibit both monophenolase and diphenolase activity of mushroom tyrosinase. The lag time of tyrosine oxidation catalyzed by mushroom tyrosinase was obviously lengthened; 0.337 mM of tiliroside resulted in the lag time extension from 46.7 s to 435.1 s. A kinetic analysis shown that tiliroside was a competitive inhibitor for monophenolase and diphenolase with Ki values of 0.052 mM and 0.26 mM, respectively. Furthermore, tiliroside showed 34.5% (p < 0.05) inhibition of intracellular tyrosinase activity and 54.1% (p < 0.05) inhibition of melanin production with low cytotoxicity on B16 mouse melanoma cells at 0.168 mM. In contrast, arbutin displayed 9.1% inhibition of cellular tyrosinase activity and 29.5% inhibition of melanin production at the same concentration. These results suggested that tiliroside was a potent tyrosinase inhibitor and might be used as a skin-whitening agent and pigmentation medicine.

Effects of hydroquinone and its glucoside derivatives on melanogenesis and antioxidation: Biosafety as skin whitening agents

The biosafety of hydroquinone and its derivatives as skin whitening agent remains controversial. Here, we investigated the effects of hydroquinone, arbutin, and deoxyarbutin (d-arb) on melanogenesis and antioxidation using cultured melan-a melanocytes in the presence or absence of ultraviolet A (UVA)-induced oxidative stress and determined whether d-arb enables to be an alterative to hydroquinone and arbutin for skin whitening use. d-arb was synthesized in this study by removing all hydroxyl groups from the glucose side-chain of arbutin. Tyrosinase activity was measured by (14)C-tyrosine incorporation, the intracellular reactive oxygen species (ROS) level was monitored by H(2)DCFDA fluorescence labeling, and the cell viability was determined by MTT assay in murine melan-a melanocytes treated with hydroquinone, arbutin and deoxyarbutin in the presence or absence of UVA-induced oxidative stress. The cytotoxicity of hydroquinone and arbutin except for d-arb was increased while the cells exposed to a nontoxic dose (3J/cm(2)) of UVA irradiation. Suppressed ROS generation was noted by the treatment of d-arb to compare with arbutin and hydroquinone. All three compounds had a similar inhibition on tyrosinase activity in dose-dependent manners with two- to three-fold decreases over the untreated control. There was no change in expression of tyrosinase protein in cells treated with arbutin or hydroquinone, but a decreased protein expression of tyrosinase was seen in deoxyarbutin-treated cells. Deoxyarbutin exerts potent tyrosinase inhibition, lessened cytotoxicity, and certain antioxidation potential, may serve as an effective and safe alternative to hydroquinone for use in skin whitening.

N-[(Dihydroxyphenyl)acyl]serotonins as potent inhibitors of tyrosinase from mouse and human melanoma cells

A series of N-acyl derivatives of tyramine, tryptamine, and serotonin were synthesized and tested on anti-melanogenic activity. The serotonin derivatives such as N-caffeoylserotonin (3) and N-protocatechuoylserotonin (9) were inhibitory to tyrosinase from mouse B16 and human HMV-II melanoma cells, while the corresponding derivatives of tryptamine and 5-methoxytryptamine were almost inactive or less active than the serotonin derivatives. The inhibitory activity of the serotonin derivatives increased with increasing number of phenolic hydroxyl groups in the acyl moiety. Melanin formation in the culture of B16 cells was suppressed by 3 and 9 with no cytotoxicity in the concentration range tested (IC50=15, 3 and 111μM for 3, 9, and kojic acid, respectively). Thus the N-acylserotonin derivatives having a dihydroxyphenyl group are potential anti-melanogenic agents. Their inhibition of tyrosinase is primarily performed through the 5-hydroxyindole moiety and further strengthened by the phenolic hydroxyl groups in the acyl moiety.

An updated review of tyrosinase inhibitors.

Tyrosinase is a multifunctional, glycosylated, and copper-containing oxidase, which catalyzes the first two steps in mammalian melanogenesis and is responsible for enzymatic browning reactions in damaged fruits during post-harvest handling and processing. Neither hyperpigmentation in human skin nor enzymatic browning in fruits are desirable. These phenomena have encouraged researchers to seek new potent tyrosinase inhibitors for use in foods and cosmetics. This article surveys tyrosinase inhibitors newly discovered from natural and synthetic sources. The inhibitory strength is compared with that of a standard inhibitor, kojic acid, and their inhibitory mechanisms are discussed.

Tyrosinase inhibitory constituents from the stems of Maackia fauriei

Bioassay-guided investigation of the stems of Maackia fauriei led to the isolation of seven flavonoid constituents, formononetin (1), genistein (2), daidzein (3), texasin (4), tectorigenin (5), odoratin (6) and mirkoin (7). Their structures were elucidated on the basis of spectral studies as well as by comparison with literature data. Tyrosinase inhibition activities were carried out on the isolated compounds. Among these, mirkoin (7) was identified as a potent tyrosinase inhibitor. It inhibited mushroom tyrosinase with an IC(50) value of 0.005 mm, which is ten times more active than kojic acid (IC(50) = 0.045 mm). The inhibition kinetics, analysed by Lineweaver-Burk plots, indicated mirkoin (7) to be a competitive inhibitor of tyrosinase when L-tyrosinase was used as a substrate. The results suggest that hydroxyl groups at C-4' in the B ring of flavonoids play an important role in the tyrosinase inhibition activities. Interestingly, compounds 4-7 were isolated for the first time from this plant.

PRELIMINARY STUDIES ON THE USE OF WATER ACTIVITY (AW) MEASUREMENTS FOR POSSIBLE APPLICATIONS IN THE PLANT EXTRACT INDUSTRY

Artocarpus lakoocha heartwood extract (Family Moraceae) and its main active constituent oxyresveratrol are potent tyrosinase inhibitors. Recently we have shown that the extract lightened the skin in volunteers and possesses several ROS scavenging activities [1, 2]. In this study we evaluated A. lakoocha heartwood extract and oxyresveratrol for their anti-aging activities in cultured fibroblasts. Using the MTT assay, the proliferative effect of A. lakoocha extract and that of oxyresveratrol was similar to the one of epigallocatechin gallate, french pine bark extract, L-ascorbic acid and Trolox® in the same concentration range (25 – 100 µg/ml). All the test antioxidants were also capable of protecting the fibroblasts against cell damages caused by hydrogen peroxide and UV-A radiation. Based on the extent of the LDH release from the fibroblasts, A. lakoocha, oxyresveratrol, pine bark and Trolox® caused less membrane irritation than L-ascorbic acid and EGCG when compared at the same concentration (100µg/ml). A. lakoocha and oxyresveratrol also showed a good anti-collagenase activity, with the respective mean IC50 of 58.8 and 153.1 µg/mL, which were less potent than EGCG (8.0 µg/mL) and pine bark (21.9 µg/mL) but much more potent than L-ascorbic acid (1.331 mg/mL) and Trolox® (2.348 mg/mL). Moreover, both A. lakoocha and oxyresveratrol could reduce the extent of DNA damages caused by UV-A as detected by flow cytometry. In conclusion, the multi-functional beneficial effects of A. lakoocha heartwood extract may have a strong potential for the use in cosmetic and other health-related products. Acknowledgements: National Research Council of Thailand provided funding.

Potent Antielastase and Antityrosinase Activities of Astilbe chinensis

Problem statement: In the current scenario, photo-aging is a major problem causing skin wrinkling and hyperpigmentation. Therefore, elastase and tyrosinase inhibitors play an important role in the treatment of skin aging and thus, gaining a special attention in cosmetic industries. Approach: In the screening of Korean medicinal plants to search the potent elastase and tyrosinase inhibitors, the extract of the rhizomes of Astilbe chinensis (A. chinensis) exhibited the strongest potential. Further the crude 100% methanolic extract of A. chinensis along with its n-hexane, methylene chloride, ethyl acetate and aqueous fractions were investigated for elastase and tyrosinase enzyme inhibition activities. Results: The A. chinensis extracts showed remarkable elastase inhibitory activities (at a concentration of 20 μg 155 μL-1 reaction) ranging from 38-92% and tyrosinase inhibition activities (at a concentration of 20 μg 150 μL-1 reaction) ranging from 2-90%. Among all the fractions, water fraction demonstrated the highest elastase and tyrosinase inhibitory activities (92 and 90%, respectively). Conclusion: Based on the noteworthy antielastase and antityrosinase activities by the rhizome of A. chinensis, it might prove a strong candidate as an active ingredient in cosmaceutical formulations and further in vitro and in vivo investigations is needed.

Antioxidative and Skin-Whitening Effect of an Aqueous Extract ofSalicornia herbacea

Salicornia herbacea (SH) is a halophyte that grows in the salt marshes along the coastline of South Korea, and is known to have antioxidative activity. In this study, the antioxidative and skin-whitening effects of SH aqueous extract were investigated in human dermal fibroblasts (HDFs) and B16 melanoma cells. The water extract of SH had potent antioxidative capacity and protected HDFs from tert-butyl hydroperoxide (tbOOH)-induced oxidative stress in a dose-dependent manner. In a cell cycle analysis, pretreatment with SH reversed the apoptotic cell death induced by tbOOH in HDFs. Additionally, the incubation of SH in mushroom tyrosinase inhibited the oxidation of l-dopa to o-dopaquinone, which implies that SH is a potent tyrosinase inhibitor. An SH treatment to B16 melanoma cells decreased the synthesis of melanin and inhibited tyrosinase activity. These results collectively indicate that SH had antioxidative and whitening effects on skin and would be a good candidate for skin rejuvenating agent.

Design, Synthesis and Biological Evaluation of Hydroxy- or Methoxy-Substituted Phenylmethylenethiosemicarbazones as Tyrosinase Inhibitors

A series of hydroxy- or methoxy-substituted phenylmethylenethiosemicarbazones were designed, synthesized and evaluated as mushroom tyrosinase inhibitors. The results demonstrated that most of target compounds had remarkable inhibitory activities on mushroom tyrosinase. Interestingly, compound 2h was found to be the most potent tyrosinase inhibitor with IC50 value of 0.18 microM. The possible interaction mode between compound 2h and tyrosinase was proposed. In addition, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities of select compounds (IC50<10.0 microM) were also investigated. Compounds 2d, 2e, 2h, 2i and 2l exhibited more potent DPPH radical scavenging activity than well-known antioxidants ascorbic acid (Vc) and tertiary butyl hydroquinone (TBHQ). These results suggested that such compounds might be utilized for the development of new candidate for treatment of dermatological disorders.