Tyrosinase Inhibitory Activity Research Articles

Study of the Effects of Novel Analogs of Calebin-A on Melanogenesis

In our previous study, we documented the anti-melanogenic efficacy of calebin-A (CBA), which is a curcuminoid analog. The effects of its newly synthesized analogs, i.e., bisdemethoxy calebin (BD), demethoxycalebin-1 (DA1), demethoxycalebin-2 (DA2), and tetrahydrocalebin-A (THCBA), on melanogenesis have not been examined yet. Herein, we evaluated these four CBA analogs to determine their impacts on the enzymatic activity of mushroom tyrosinase. Additionally, we examined their effects on melanogenesis and the tyrosinase activity in B16F10 mouse and MNT-1 human melanoma cells. The antioxidant activity of the analogs was also assessed. Our results revealed that BD was ineffective, while DA1 and DA2 showed similar antioxidant activities, with THCBA exhibiting the greatest antioxidant activity. Next, the diphenolase activity assay results revealed that DA1 showed the most excellent inhibitory efficacy, DA2 and BD showed similar inhibition profiles, and THCBA was ineffective. In addition, the results of the monophenolase activity showed a similar pattern, except that THCBA suppressed the activity. The four analogs were evaluated for any cytotoxicity over a 48 h duration in B16F10 and HaCaT keratinocytes, where DA1 exerted cytotoxicity at the concentration of 50 µM. Based on this, the analogs were evaluated over a 10–50 µM concentration range, while DA1 was evaluated over 10–35 µM. BD showed the greatest efficacy at multiple concentrations in significantly diminishing melanogenesis in hormone-stimulated B16F10 cells, while DA1 and DA2 suppressed melanin at 35 and 50 µM, respectively, and THCBA stimulated melanogenesis at 50 µM. In addition, BD and DA1 suppressed tyrosinase activity in B16F10 cells, with no effect in the case of DA2 and THCBA analogs. However, in MNT-1 cells, only DA1 showed efficacy in suppressing melanin production while the other three analogs were ineffective. Interestingly, BD and DA1 suppressed MNT-1 cell tyrosinase activity. Collectively, our results indicate that of the four analogs, DA1 merits further investigation as a potential compound for hyperpigmentation skin disorders. Additional research is necessary to delineate the molecular mechanisms underlying the melanogenesis-inhibitory effect of CBA analogs and examine their efficacy in diminishing melanogenesis in normal human melanocytes.

Cyclo(l-Pro-l-Tyr) Isolated from the Human Skin Commensal Corynebacterium tuberculostearicum Inhibits Tyrosinase.

Melanin is produced by melanocytes to protect human skin from harmful ultraviolet radiation. During skin cell renewal, melanin and dead skin cells are disposed of. However, prolonged exposure to ultraviolet rays or aging can disturb this cycle, leading to skin hyperpigmentation due to melanin accumulation. Tyrosinase is a crucial enzyme involved in melanin biosynthesis. Although various compounds, including tyrosine inhibitors, that counteract melanin accumulation have been reported, some, such as hydroquinone, are toxic and can cause vitiligo. Meanwhile, the skin is the largest organ and the outermost layer of the immune system, containing a diverse range of bacteria that produce low-toxicity compounds. In the current study, we aim to identify metabolites produced by skin microbiota that inhibit tyrosinase. Specifically, mushroom tyrosinase served as the study model. Following commensal skin bacteria screening, Corynebacterium tuberculostearicum was found to inhibit tyrosinase activity. The active compound was cyclo(l-Pro-l-Tyr); commercially available cyclo(l-Pro-l-Tyr) also exhibited inhibitory activity. Docking simulations suggested that cyclo(l-Pro-l-Tyr) binds to the substrate-binding site of mushroom tyrosinase, obstructing the substrate pocket and preventing its activity. Hence, cyclo(l-Pro-l-Tyr) might have potential applications as a cosmetic agent and food additive.

Cyclo(l-Pro-l-Tyr) Isolated from the Human Skin Commensal Corynebacterium tuberculostearicum Inhibits Tyrosinase

Melanin is produced by melanocytes to protect human skin from harmful ultraviolet radiation. During skin cell renewal, melanin and dead skin cells are disposed of. However, prolonged exposure to ultraviolet rays or aging can disturb this cycle, leading to skin hyperpigmentation due to melanin accumulation. Tyrosinase is a crucial enzyme involved in melanin biosynthesis. Although various compounds, including tyrosine inhibitors, that counteract melanin accumulation have been reported, some, such as hydroquinone, are toxic and can cause vitiligo. Meanwhile, the skin is the largest organ and the outermost layer of the immune system, containing a diverse range of bacteria that produce low-toxicity compounds. In the current study, we aim to identify metabolites produced by skin microbiota that inhibit tyrosinase. Specifically, mushroom tyrosinase served as the study model. Following commensal skin bacteria screening, Corynebacterium tuberculostearicum was found to inhibit tyrosinase activity. The active compound was cyclo(l-Pro-l-Tyr); commercially available cyclo(l-Pro-l-Tyr) also exhibited inhibitory activity. Docking simulations suggested that cyclo(l-Pro-l-Tyr) binds to the substrate-binding site of mushroom tyrosinase, obstructing the substrate pocket and preventing its activity. Hence, cyclo(l-Pro-l-Tyr) might have potential applications as a cosmetic agent and food additive.

Phytochemistry, Anti-Tyrosinase, and Anti-Diabetes Studies of Extracts and Chemical Constituents of Dicerothamnus rhinocerotis Leaves

Dicerothamnus rhinocerotis (L.f.) Koekemoer, also known as rhinoceros bush and previously called Elytropappus rhinocerotis (L.f.) Less., is from the Asteraceae plant family. The plant is traditionally used to treat indigestion, stomach ulcers, influenza, and diarrhea. This study was aimed at investigating the phytochemistry, anti-glucosidase, anti-amylase, and anti-tyrosinase effects of D. rhinocerotis as research in this area is limited. The air-dried plant materials were macerated in 80% methanol (MeOH) and fractionated between hexane, dichloromethane (DCM), ethyl acetate (EtOAc), and butanol (BuOH). Column chromatography on silica gel was employed for the isolation of the compounds. A total of six compounds (1–6) were isolated from the fractions viz. acacetin (1), 15-hydroxy-cis-clerodan-3-ene-18-oic-acid (2), acacetin-7-glucoside (3), pinitol (4), apigenin (5), and β-sitosterol-3-O-glycoside (6). Compounds 2–4 and 6 are reported for the first time from this plant. Among the different fractions, the BuOH and EtOAc fractions had strong tyrosinase inhibitory activities with IC50 values of 13.7 ± 1.71 and 11.6 ± 2.68 µg/mL, respectively, while among the isolated compounds, apigenin (5) had the strongest inhibitory activity, with an IC50 of 14.58 µM, which competes favorably with Kojic acid (17.26 µM). The anti-glucosidase assay showed good activity in three of the fractions and compound 5, while the anti-amylase assays did not show significant inhibition activity.

Design, synthesis, and anti-melanogenic efficacy of 2-mercaptobenzoxazoles with nanomolar tyrosinase activity inhibition

Tyrosinase is a metalloenzyme that contains copper(II) ions. We designed and synthesized eight known low-molecular-weight 2-mercaptobenzoxazole (2-MBO) analogs as tyrosinase inhibitors. Our focus was on the mercapto functional group, which interacts with copper ions. Analogs 1–3 exhibited mushroom tyrosinase inhibitory activity at the nanomolar level and demonstrated strong potency with extremely low half-maximal inhibitory concentration (IC50) values of 80–90 nM for l-dopa and 100–240 nM for l-tyrosine. Analogs 2, 4, and 5 showed the most potent anti-melanogenic effects in B16F10 cells, and their mode of action was demonstrated by kinetic analysis. Their anti-melanogenic effects were similar to the tyrosinase inhibition results, suggesting that their anti-melanogenic effects could be attributed to their tyrosinase inhibitory ability. Experiments using copper-chelating activity assays and changes in tyrosinase inhibitory activity with and without CuSO4 demonstrated that 2-MBO analogs inhibit tyrosinase activity by chelating the copper ions of tyrosinase. In conclusion, the 2-MBO analogs show potential as anti-melanogenic agents with potent tyrosinase inhibitory activity.

Effects of Vitamin C and SH-Polypeptide-10 Cosmetic Ingredients on Wrinkle Improvement and Skin Whitening

In this study, 20 female subjects in their 30s to 50s used cosmetics containing the main ingredients vitamin C and SH-Polypeptide-10 in an environment exposed to ultraviolet rays, and underwent clinical trials to determine the effects of improving wrinkles, brightness, and whitening of the skin. Efficacy evaluation was performed. Wrinkles around the eyes significantly decreased from 0.0592 to 0.0507(p<0.001), and the wrinkle improvement effect decreased by 16.78%(p<0.05). Skin brightness significantly decreased from 65.44 to 67.04 in the experimental group(p<0.001), and skin brightness increased by 2.45%(p<0.05). Additionally, the skin whitening effect significantly decreased from 66.38 to 55.51(p<0.001), and melanin pigment decreased by 19.57%(p<0.05). The cosmetics used in this experiment were shown to have antioxidant effects that protect cells from oxidative stress, increase transdermal permeability, promote epidermal cell growth and cell regeneration, inhibit tyrosinase activity and promote collagen formation. Overall, the use of cosmetics containing vitamin C and SH-Polypeptide-10 as main ingredients resulted in significant improvement in the experimental group, which can be seen as having a positive effect on improving wrinkles around the eyes and skin whitening.

Efficiency of freeze- and spray-dried microbial preparation as active dried starter culture in kombucha fermentation.

Kombucha is a widely consumed fermented beverage produced by fermenting sweet tea with a symbiotic culture of bacteria and yeast (SCOBY). The dynamic nature of microbial communities in SCOBY may pose challenges to production scale-up due to unpredictable variations in microbial composition. Using identified starter strains is a novel strategy to control microorganism composition, thereby ensuring uniform fermentation quality across diverse batches. However, challenges persist in the cultivation and maintenance of these microbial strains. This study examined the potential of microencapsulated kombucha fermentation starter cultures, specifically Komagataeibacter saccharivorans, Levilactobacillus brevis and Saccharomyces cerevisiae, through spray-drying and freeze-drying. Maltodextrin and gum arabic-maltodextrin were employed as carrier agents. Our results revealed that both spray-dried and freeze-dried samples adhered to physicochemical criteria, with low moisture content (2.18-7.75%) and relatively high solubility (65.75-87.03%) which are appropriate for food application. Freeze-drying demonstrated greater effectiveness in preserving bacterial strain viability (88.30-90.21%) compared to spray drying (74.92-78.66%). Additionally, the freeze-dried starter strains demonstrated similar efficacy in facilitating kombucha fermentation, compared to the SCOBY group. The observations included pH reduction, acetic acid production, α-amylase inhibition and elevated total polyphenol and flavonoid content. Moreover, the biological activity, including antioxidant potential and in vitro tyrosinase inhibition activity, was enhanced in the same pattern. The freeze-dried strains exhibited consistent kombucha fermentation capabilities over a three-month preservation, regardless of storage temperature at 30 or 4 °C. These findings highlight the suitability of freeze-dried starter cultures for kombucha production, enable microbial composition control, mitigate contamination risks and ensure consistent product quality. © 2024 Society of Chemical Industry.

Anti-Melanogenic Activity of Ethanolic Extract from Garcinia atroviridis Fruits Using In Vitro Experiments, Network Pharmacology, Molecular Docking, and Molecular Dynamics Simulation.

Melanin, the pigment responsible for human skin color, increases susceptibility to UV radiation, leading to excessive melanin production and hyperpigmentation disorders. This study investigated the ethanolic extract of Garcinia atroviridis fruits for its phenolic and flavonoid contents, antioxidant activity, and impact on melanogenesis pathways using qRT-PCR and Western blot analysis. Utilizing network pharmacology, molecular docking, and dynamics simulations, researchers explored G. atroviridis fruit extract's active compounds, targets, and pharmacological effects on hyperpigmentation. G. atroviridis fruit extract exhibited antioxidant properties, scavenging DPPH• and ABTS•+ radicals radicals and chelating copper. It inhibited cellular tyrosinase activity and melanin content in stimulated B16F10 cells, downregulating TYR, TRP-1, phosphorylated CREB, CREB, and MITF proteins along with transcription levels of MITF, TYR, and TRP-2. LC-MS analysis identified thirty-three metabolites, with seventeen compounds selected for further investigation. Network pharmacology revealed 41 hyperpigmentation-associated genes and identified significant GO terms and KEGG pathways, including cancer-related pathways. Kaempferol-3-O-α-L-rhamnoside exhibited high binding affinity against MAPK3/ERK1, potentially regulating melanogenesis by inhibiting tyrosinase activity. Stable ligand-protein interactions in molecular dynamics simulations supported these findings. Overall, this study suggests that the ethanolic extract of G. atroviridis fruits possesses significant antioxidant, tyrosinase inhibitory, and anti-melanogenic properties mediated through key molecular targets and pathways.

Comparative evaluation of six commercial adult toothpaste formulations reveals cytotoxicity and altered functions in a human oral melanocyte model: an in vitro study.

This study aims to compare six commercial adult toothpaste (labeled as A, B, C, D, E, and F) for cytotoxicity and melanocyte function alterations in vitro using primary human epidermal melanocytes from a Caucasian donor (HEMn-LP cells) as a model of oral melanocytes. Cells were incubated with toothpaste extracts (50% w/v) in culture media at dilutions (1:25, 1:50, 1:100, 1:200, 1:500, 1:800, and 1:1000) for 24h. MTS and LDH assays were used to assess cytotoxicity. The effects of noncytotoxic toothpaste concentrations on melanocyte functional endpoints were then examined using spectrophotometric methods. All toothpaste showed concentration-dependent cytotoxicity that was heterogeneous across toothpaste containing SLS detergent. IC50 values of cytotoxicity followed the order: A = E > C > B > D > F. To compare toothpaste, they were tested at 1:800 and 1:1000 dilutions that were noncytotoxic after 24h. None of the toothpaste affected cellular melanin production. However, toothpaste A, C, and D suppressed tyrosinase activity at both dilutions, while toothpaste B suppressed tyrosinase activity only at 1:800 dilution. Toothpaste A, C, E, and F elevated ROS production at 1:800 dilution, with no change at 1:1000 dilution. Toothpaste has a heterogeneous effect on melanocytes. Toothpaste B, E, and F at 1:1000 dilution were the safest as they did not alter melanocyte functions at this dilution, although toothpaste F is the least cytotoxic of these. Future studies are necessary to expand these results in a physiological environment of oral tissue. The findings of this study provide novel insight into the biocompatibility studies of toothpaste on oral melanocytes. They can aid dental practitioners and consumers in selecting noncytotoxic toothpaste that do not contribute to ROS generation by melanocytes in the oral cavity or lead to cytotoxicity and impaired cellular function.

Phytochemical study, antioxidant and tyrosinase inhibitory activities of Pentzia monodiana Maire

Chemical investigation of the aerial parts of Pentzia monodiana Maire led to the isolation and identification of one sesquiterpene lactone glucoside of the guaianolide type (dihydropseudoivalin-4-O-β-d-glucopyranoside), along with nine known compounds including one diterpenoid, two sesquiterpenoids, three lignanes and three flavonoids. Their structures were established on the basis of spectroscopic analysis. All these compounds were evaluated for their DPPH radical scavenging and tyrosinase inhibitory activities. Only lignanes and flavonoids showed good to moderate DPPH radical scavenging activity with EC50 ranging from 10.6 to 47.5 μM. The new sesquiterpene lactone glucoside showed low tyrosinase inhibitory activity whereas the isolated lignanes and flavonoids exhibited a moderate activity with IC50 ranging from 45.4 to 97.2 μM).

Phytochemical profiling, antioxidant, and tyrosinase inhibitory potential of the Acacia cyclops trunk bark: in vitro combined with in silico approach.

The aim of this study was to analyze the phytochemical profile of Acacia cyclops trunk bark ethyl acetate extract using LC-tandem mass spectrometry for the first time, along with evaluating its antioxidant and anti-tyrosinase properties. Consequently, we determined the total phenolic and flavonoid contents of the extract under investigation and identified and quantified 19 compounds, including phenolic acids and flavonoids. In addition to assessing their antioxidant potential against DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2'-azino-bis-[3-ethylbenzothiazoline-6-sulfonic] acid) assays, in vitro and in silico studies were conducted to evaluate the tyrosinase inhibitory properties of the A. cyclops extract. The ethyl acetate trunk bark extract exhibited a substantial total phenolic content and demonstrated significant antioxidant activity in terms of free radical scavenging, as well as notable tyrosinase inhibitory action (half-maximal inhibitory concentration [IC50] = 14.08 ± 1.10 μg/mL). The substantial anti-tyrosinase activity of the examined extract was revealed through molecular docking analysis and druglikeness prediction of the main selected compounds. The findings suggest that A. cyclops extract holds promise as a potential treatment for skin hyperpigmentation disorders.

Unveiling the Potential of Ultrasonic-Assisted Ethanol Extract from Sargassum horneri in Inhibiting Tyrosinase Activity and Melanin Production in B16F10 Murine Melanocytes.

Melanogenesis, regulated by genetic, hormonal, and environmental factors, occurs in melanocytes in the basal layer of the epidermis. Dysregulation of this process can lead to various skin disorders, such as hyperpigmentation and hypopigmentation. Therefore, the present study investigated the effect of ultrasonic-assisted ethanol extract (SHUE) from Sargassum horneri (S. horneri), brown seaweed against melanogenesis in α-melanocyte-stimulating hormone (MSH)-stimulated B16F10 murine melanocytes. Firstly, yield and proximate compositional analysis of the samples were conducted. The effect of SHUE on cell viability has been evaluated by using 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. After that, the melanin content and cellular tyrosinase activity in α-MSH-stimulated B16F10 murine melanocytes were examined. Western blot analysis was carried out to investigate the protein expression levels of microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP1), and tyrosinase-related protein-2 (TRP2). In addition, the effect of extracellular signal-regulated kinase (ERK) on the melanogenesis process was assessed via Western blotting. As per the analysis, SHUE contained the highest average yield on a dry basis at 28.70 ± 3.21%. The findings showed that SHUE reduced the melanin content and cellular tyrosinase activity in α-MSH-stimulated B16F10 murine melanocytes. Additionally, the expression levels of MITF, TRP1, and TRP2 protein were significantly downregulated by SHUE treatment in α-MSH-stimulated B16F10 murine melanocytes. Moreover, SHUE upregulated the phosphorylation of ERK and AKT in α-MSH-stimulated B16F10 murine melanocytes. In addition, experiments conducted using the ERK inhibitor (PD98059) revealed that the activity of SHUE depends on the ERK signaling cascade. These results suggest that SHUE has an anti-melanogenic effect and can be used as a material in the formulation of cosmetics related to whitening and lightening.

Enhancing Secondary Metabolite Production in Pelargonium graveolens Hort. Cell Cultures: Eliciting Effects of Chitosan and Jasmonic Acid on Bioactive Compound Production

This study explores the effects of chitosan (CHT) and jasmonic acid (JA) elicitors on rose-scented geranium (Pelargonium graveolens Hort.) cell suspension cultures, aiming to enhance the production of phenolics and flavonoids and antioxidant properties. Elicitation with CHT and JA resulted in varied biomass yields and callus characteristics, with higher concentrations generally leading to increased phenolic accumulation. Optimal biomass was achieved with CHT4 (75 mg/mL) and JA3 (50 µM) treatments. HPLC-DAD analysis revealed changes in phenolic compound composition and quantities, with specific compounds induced by either CHT4 or JA3. For instance, gallic acid content increased significantly in CHT4-treated cells, while catechin content increased notably in both CHT4 and JA3 treatments. Antioxidant enzyme activities like superoxide dismutase and peroxidase increased with elicitor concentration, particularly in CHT4 and JA3 treatments. Both treatments exhibited potent antioxidant activity, with JA3 exhibiting the lowest IC50 value in the DPPH assay and highest total antioxidant capacity (TAC) values. Surprisingly, both CHT4 and JA3 extracts effectively inhibited tyrosinase activity. These findings underscore the efficacy of CHT and JA elicitors in enhancing phenolic and flavonoid production, boosting antioxidant capacity, and inhibiting tyrosinase activity in P. graveolens cultures, offering promising implications for further research and industrial applications in pharmaceutical and cosmetic sectors.

Physicochemical Characterization, Antioxidant and Tyrosinase Inhibitory Activities of Coffea Robusta Monofloral Honey from Dak Lak Province, Vietnam.

Robusta coffee blossom honey stands as a key regional product in Dak Lak province, Vietnam. Despite its significance, there exists a dearth of scientific data for assessing its quality. This study aims to fill this gap by characterizing the physicochemical properties and biological activities of coffee blossom honeys from three distinct sub-regions within Dak Lak province, Vietnam. These activities include ferric reducing power (FRP), DPPH and ABTS radical scavenging, as well as tyrosinase inhibitory activities. Moreover, the study compares these honey samples with other popular varieties in Vietnam, such as Lychee and Longan honeys. The physicochemical parameters of the honey samples meet the standards set by Codex Alimentarius 2001. Through UPLC analysis, eleven compounds were identified, with caffeine serving as a marker for coffee honey. Furthermore, by employing multiple factor analysis (MFA), it was observed that certain physicochemical properties correlate positively with tyrosinase inhibitory, DPPH, ABTS free radicals scavenging activities, and FRP. Notably, tyrosinase inhibitory activity exhibited a positive correlation with antioxidant activity. These findings underscore the high quality of Coffea robusta honey, showcasing its potent antioxidant and tyrosinase inhibitory activities.

Bionic synthesis of novel monoterpenoid indole alkaloid-like analogs with tyrosinase inhibition activity based on loganetin

A series of novel monoterpenoid indole alkaloid (MIA)-like analogs (1–24) were synthesized by using a biomimetic synthetic strategy and combinatorial chemistry. The tyrosinase inhibitory activities and antioxidant properties of these compounds were assessed through tyrosinase inhibition assay, DPPH and ABTS free radicals scavenging assays, respectively. The results showed that most synthesized compounds (2, 4–8, 10–12, 14–17, 19) exhibited significant inhibitory activities against both monophenolase and diphenolase. In particular, compound 14, with an IC50 value of 0.18 ± 0.02 mM, displayed approximately 72-fold stronger monophenolase inhibitory activity than that of loganetin with an IC50 value of 12.76 ± 1.00 mM. Similarly, compound 17 exhibited the best diphenolase inhibitory activity (IC50, 0.30 ± 0.09 mM), which was approximately 47 times higher than that of loganetin (IC50, 14.05 ± 0.47 mM). Additionally, six compounds (3, 13–17) showed significant in vitro antioxidant activities. Compound 17 exhibited the most promising ABTS radical scavenging activity with an IC50 value of 2.90 ± 0.07 μM, while compound 15 exhibited the highest DPPH free radical scavenging capacity with an IC50 value of 17.59 ± 0.21 μM. The structure-activity relationships analysis revealed that the substituents at C-5 and C-11 in the tryptamine moiety might significantly impact antioxidant activity. Furthermore, the detailed interactions and binding modes of the most potent derivative toward tyrosinase were elucidated by a molecular docking study, which indicated that 14 and 17 might exert their inhibitory effects by binding to key amino acid residues (His 85 and His 263) at the tyrosinase active site.

Mitigation of oxidative stress and inflammatory factors, along with the antibrowning and antimicrobial effects of cassia seed microbial fermentation solution.

Cassia seeds, originating from the mature seeds of leguminous cassia species, possess pharmacological effects attributed to their rich composition of various active ingredients, notably anthraquinones. While current research predominantly focuses on pharmaceutical extractions, there has been limited progress in fermentation studies. Our study aimed to enhance the content of active compounds such as anthraquinones, flavonoids, and polyphenols using microbial fermentation techniques. We specifically optimized a fermentation system through a single-factor experimental design. The antioxidant properties of the fermentation solution were validated through assays involving HaCaT cells and zebrafish. We observed effective suppression of inflammatory reactions in both RAW264.7 cells and transgenic zebrafish by the fermentation solution. Moreover, significant inhibition of tyrosinase activity and melanin production was evident in B16-F10 cells and zebrafish. Positive outcomes were also obtained in antibacterial assays and chick embryo experiments. These findings highlight the potential of cassia seed fermentation solution as a safe and eco-friendly material in food chemistry and biomedical sciences.

Diversity in Pyracantha fortuneana fruits maturity stages enables discrepancy in the phenolic compounds, antioxidant activity, and tyrosinase inhibitory activity.

Pyracantha fortuneana (P. fortuneana) fruit is a wild fruit that is popular because of its delicious taste and numerous nutrients, and phenolic compounds are considered to be the main bioactive components in P. fortuneana fruits. However, the relationship between phenolic compounds and their antioxidant and tyrosinase (TYR) inhibitory activities during the ripening process is still unclear. The study compared the influence of the five developmental stages on the accumulation of phenolic compounds, antioxidant activity, and TYR inhibitory activity in the fruits of P. fortuneana. The compounds were identified by offline two-dimensional liquid chromatography-electrochemical detection (2D-LC-ECD) combined with liquid chromatography-tandem mass spectrometry, and the main active ingredients were quantified. The results showed that stage II had higher total phenolic and flavonoid content, as well as higher antioxidant and TYR inhibitory activity, but the total anthocyanin content was lowest at this stage. A total of 30 compounds were identified by 2D-LC-ECD. Orthogonal partial least squares discriminant analysis screened out six major potential markers, including phenolic acids, procyanidins, and flavonoids. In addition, it was found that caffeoylquinic acids, procyanidins, and flavonoids were higher in stage II than in stages I, III, IV, and V, whereas anthocyanins accumulated gradually from stages III to V. Therefore, this study suggests that the changes in antioxidant and TYR inhibitory activities of P. fortuneana during the five developmental stages may be due to the transformation of procyanidins, caffeoylquinic acids, and phenolic glycosides into other forms during the fruit maturation process. Practical Application: Differences in chemical constituents, antioxidant, and tyrosinase inhibitory activities in fruit maturity stages of P. fortuneana were elucidated to provide reference for rational harvesting and utilization of the fruits and their bioactive components. These findings are expected to provide a comprehensive assessment of the bioactive profile and guide the food industrial production.

Active Constituents with Tyrosinase Inhibitory Activities from Waste Tobacco Leaves.

One novel compound, (R)-3, 6-diethoxy-4-hydroxycyclohex-3-en-1-one (1) and thirteen known compounds were isolated from the waste tobacco leaves. The structures of two compounds (1-2) were confirmed and attributed firstly by the extensive spectroscopic data, including 1D/2D NMR, IR, HR-ESI-MS, CD, and ECD spectra. Notably, seven compounds (2, 3, 9, 10, 11, 12, and 13) exhibited better tyrosinase inhibitory activity than the positive control kojic acid. The binding modes of these compounds revealed that their structure formed strong hydrogen bonds and van der Waals forces with the active sites of tyrosinase. These results indicated that waste tobacco leaves are good resources for developing tyrosinase inhibitors.

Discovery of superior bioactive peptides of two edible Lentinus mushrooms protein hydrolysate in biological activities: tyrosinase inhibitory and antioxidant activity

Discovery of superior bioactive peptides of two edible Lentinus mushrooms protein hydrolysate in biological activities: tyrosinase inhibitory and antioxidant activity

Evaluation of a panel of furochromenones as the activator and inhibitor of tyrosinase.

Tyrosinase is a copper-containing enzyme involved in the biosynthesis of melanin pigment. While the excess production of melanin causes hyperpigmentation of human skin, hypopigmentation results in medical conditions like vitiligo. Tyrosinase inhibitors could be used as efficient skin whitening agents and tyrosinase agonists could be used for enhanced melanin synthesis and skin protection from UV exposure. Among a wide range of tyrosinase-regulating compounds, natural and synthetic derivatives of furochromenones, such as 8-methoxypsoralen (8-MOP), are known to both activate and inhibit tyrosinase. We recently reported a synthetic approach to generate a variety of dihydrofuro[3,2-c]chromenones and furo[3,2-c]chromenones in a metal-free condition. In the present study, we investigated these compounds for their potential as antagonists or agonists of tyrosinase. Using fungal tyrosinase-based invitro biochemical assay, we obtained one compound (3k) which could inhibit tyrosinase activity, and the other compound (4f) that stimulated tyrosinase activity. The kinetic studies revealed that compound 3k caused 'mixed' type tyrosinase inhibition and 4f stimulated the catalytic efficiency. Studying the mechanisms of these compounds may provide a basis for the development of new effective tyrosinase inhibitors or activators.