Antityrosinase mechanism of ellagic acid in vitro and its effect on mouse melanoma cells

7-(Diethylamino) coumarin-3-carboxylic acid as a novel antibrowning agent: Activity and mechanism

Browning caused by polyphenol oxidase (PPO) and microorganisms significantly impacts the nutritional quality of fruits and vegetables. This study identified 7-(Diethylamino) coumarin-3-carboxylic acid (7-DCCA) as an effective inhibitor of both PPO and bacteria. Enzyme assays revealed that 7-DCCA competitively inhibits PPO activity with an IC50 value of 0.275 ± 0.002 mM. Fluorescence and molecular simulation methods demonstrated that 7-DCCA forms a complex with PPO through hydrogen bonding and hydrophobic interactions, altering the enzyme's structure and reducing its activity. Thermogravimetric and differential scanning calorimetry (DSC) assays showed that 7-DCCA stabilizes PPO, delaying its thermal decomposition. Antibacterial tests proved that 7-DCCA inhibits Staphylococcus aureus and Escherichia coli by disrupting cell membranes. Additionally, 7-DCCA suppressed PPO and peroxidase activities, delaying phenolic oxidation and preventing browning in fruits and vegetables. Cytotoxicity assays confirmed its safety, with over 85 % cell viability at concentrations up to 0.1 mM. Stability experiments verified that 7-DCCA had greatly light and thermal stability. This study highlighted 7-DCCA as a promising antibrowning agent with potential application in food preservation.

Ethanolic Extract of Bergenia purpurascens Exhibits Antimelanogenic Effects in B16F10 Cells through Multiple Mechanisms That Suppress Tyrosinase

Bergenia purpurascens, renowned for its antibacterial and antioxidant properties, remains relatively unexplored in its impact on melanogenesis. This study delves into the antimelanogenic potential of the ethanol extract derived from B. purpurascens (BPE). Our investigations reveal the robust antioxidant capabilities of the BPE, along with its effective inhibition of mushroom tyrosinase activity. Remarkably, these effects were significantly stronger than those observed with arbutin, the positive control. In vitro assays demonstrate the BPE's efficacy in reducing the melanin content and tyrosinase activity in α-MSH-stimulated B16F10 cells. Immunofluorescence and qPCR analyses further reveal the BPE's ability to inhibit MITF-mediated gene expression levels associated with melanogenesis, including Trp-1, Trp-2, and tyrosinase. These findings suggest that the extract operates through dual mechanisms, suppressing both tyrosinase activity and key transcription factor-mediated downstream signaling. Utilizing UPLC-MS/MS analysis, we identified six key compounds implicated in tyrosinase activity inhibition and melanogenesis suppression. Docking simulations confirm moderate binding affinities between these compounds and tyrosinase. This study highlights the potential of B. purpurascens as a novel natural agent for depigmentation in medicinal and cosmetic applications, elucidating its dual mechanism of action in melanogenesis inhibition.

Computational studies of tyrosinase inhibitors

Computational studies have significantly advanced the understanding of tyrosinase (TYR) function, mechanism, and inhibition, accelerating the development of more effective and selective inhibitors. This chapter provides an overview of in silico studies on TYR inhibitors, emphasizing key inhibitory chemotypes and the main residues involved in ligand-target interactions. The chapter discusses tools applied in the context of TYR inhibitor development, e.g., structure-based virtual screening, molecular docking, artificial intelligence, and machine learning algorithms.

UHPLC-ESI-QTOF-MS metabolite profiles of different extracts from Pelargonium endlicherianum parts and their biological properties based on network pharmacological approaches

In the present study, we aimed to investigate the chemical profiles and biological activities of different extracts (ethyl acetate, dichloromethane, ethanol, and water) of Pelargonium endlicherianum parts (aerial parts and roots). Free radical scavenging, reducing power, phosphomolybdenum, and metal chelating were assayed for antioxidant properties. To detect enzyme inhibitory properties, cholinesterase, amylase, glucosidase, and tyrosinase were chosen as target enzymes. The ethanol extract of the aerial parts contained higher amounts of total bioactive compounds (120.53 mg GAE/g-24.46 mg RE/g). The ethanol and water extracts of these parts were tentatively characterized by UHPLC-ESI-QTOF-MS and 95 compounds were annotated. In addition, the highest acetylcholiesterase (3.74 mg GALAE/g) and butyrylcholinesterase (3.92 mg GALAE/g) abilities were observed by the ethanol extract of roots. The water extract from aerial parts exhibited the most pronounced inhibitory effects on multiple cancer cell lines, especially A549 (IC50: 23.2 µg/mL) and HT-29 (IC50: 27.43 µg/mL) cells. Using network pharmacology, P. endlicherianum compounds were studied against cancer, revealing well-connected targets such as epidermal growth factor receptor (EGFR), phosphoinositide-3-kinase (PI3K), AKT, receptor tyrosine-protein kinase erbB-2, and growth factor receptor bound protein 2 (GRB2) with significant impact on cancer-related pathways. The results could open a new path from natural treasure to functional applications with P. endlicherianum and highlight a new study on other uninvestigated Pelargonium species.

6,7-Bis-(2-methoxyethoxy)-4(3H)-quinazolinone as a novel inhibitor of tyrosinase and potential anti-browning agent of fresh-cut apples

6,7-Bis-(2-methoxyethoxy)-4(3H)-quinazolinone (BMEQ) was selected from quinazolinones for its strong tyrosinase inhibitory activity (IC50 = 160 ± 6 μM). It suppressed tyrosinase activity in a competitive way and quenched the fluorescence of the enzyme through a static mechanism. The binding of BMEQ to tyrosinase increased the hydrophobicity of the latter and facilitated non-radiative energy transfer between them. The formation of BMEQ-tyrosinase complex was driven by hydrogen bonds and hydrophobic interactions, and it loosened the basic framework structure of tyrosinase, affecting the conformation of the enzyme, and leading to a decrease in tyrosinase activity. In addition, the BMEQ postponed the oxidation of phenolics and flavonoids by inhibiting polyphenol oxidase (PPO) and peroxidase (POD), which resulted in the inhibition of the browning of fresh-cut apples. This study identified a novel tyrosinase inhibitor BMEQ and verified its potential application for improving the preservation of postharvest fruits.

Treatments of heating and ultrasound improve the inhibition of gallocatechin gallate on tyrosinase

BACKGROUND

Gallocatechin gallate (GCG), a catechin of tea polyphenols, possesses inhibitory ability against tyrosinase, but few studies have reported how common processing methods affect it. In this research, the influence of heating and ultrasound treatments on the inhibition of GCG against tyrosinase was explored by ultraviolet-visible absorption, fluorescence spectroscopy, high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry.

RESULTS

Both heating and ultrasound treatments of GCG alone improved GCG's inhibitory ability against tyrosinase compared with the untreated, and a combination of heating and ultrasound treatment (100 °C, 20 min + 630 W, 20 min) further decreased the relative tyrosinase activity to 26.8%. The treated GCG exhibited a stronger fluorescence quenching effect on tyrosinase, but did not have any influence on the static quenching mechanism. Compared to the untreated GCG, the binding constants of treated GCG by heating, ultrasound and their combination with tyrosinase significantly increased, but the number of binding sites was still approximately one and the main driving force of the treated GCG was still hydrophobic interaction. After treatments of heating, ultrasound and their combination, the composition of GCG solutions was changed.

CONCLUSION

The enhanced inhibition of treated GCG on tyrosinase may be due to partial conversion of GCG into epigallocatechin-3-gallate (EGCG) and gallic acid (GA), which may cooperate with GCG to better inhibit the enzyme activity. This study has provided some valuable information for the application of catechins against tyrosinase in food processing and cosmetic industry. © 2022 Society of Chemical Industry.

Antioxidant and in vitro cosmeceutical activities of chestnut inner shell fermented by Monascus kaoliang

Chestnut inner shell (CIS) was fermented at 30 °C for 12 day using Monascus kaoliang, either in solid or submerged state, and alcohol extracts (70% ethanol) of the fermented CIS were examined for their antioxidant (total phenol content and diphenylpicrylhydrazyl radical scavenging activity) and in vitro cosmeceutical activities (tyrosinase and elastase inhibitory activities). Both activities were significantly increased by the M. kaoliang-fermentation, more apparently by submerged fermentation (SMF) than by solid-state fermentation (SSF). The cosmeceutical activity reached its maximum value on the 3rd day of fermentation. The residual amounts of phenolic acids and catechins in the CIS extracts were increased by the fermentation, up to 395.0 and 344.3 µg/g, respectively. More phenolic acids were produced by SMF than SSF, whereas more catechins were produced by SSF than SMF. Therefore, SMF using M. kaoliang was an efficient process for the utilization of CIS as a source of cosmeceuticals.

Inhibition of albendazole and 2-(2-aminophenyl)-1H-benzimidazole against tyrosinase: mechanism, structure-activity relationship, and anti-browning effect

BACKGROUND

Tyrosinase is the key enzyme involved in enzymatic browning of plant-derived foods. Inhibition of tyrosinase activity contributes to the control of food browning. Due to safety regulations or other issues, most identified tyrosinase inhibitors are not suitable for practical use. Therefore, it is necessary to search for novel tyrosinase inhibitors. In this study, the anti-tyrosinase activity and mechanism of albendazole and 2-(2-aminophenyl)-1H-benzimidazole (2-2-A-1HB) were investigated through ultraviolet-visible absorption spectroscopy, fluorescence spectra, molecular docking, and molecular dynamic (MD) simulation. The anti-browning effect of albendazole on fresh-cut apples was then elucidated.

RESULTS

Albendazole and 2-2-A-1HB were both efficient tyrosinase inhibitors with IC₅₀ of 51 ± 1.5 and 128 ± 1.3 μmol L^-1 , respectively. Albendazole suppressed tyrosinase non-competitively and formed tyrosinase-albendazole complex statically. Hydrogen bond and hydrophobic interaction were major driving forces in stabilizing the tyrosinase-albendazole complex. While 2-2-A-1HB inhibited the enzyme competitively and quenched its intrinsic fluorescence through a static mechanism, it generated strong binding affinity with tyrosinase through hydrophobic interaction. MD simulations further validated that albendazole/2-2-A-1HB could form stable complexes with tyrosinase and loosened its basic framework structure, leading to a change in secondary structure and conformation. In addition, albendazole could delay the browning of fresh-cut apples by inhibiting the activity of polyphenol oxidase, peroxidase and phenylalanine ammonia-lyase, and reducing the oxidation of phenolic compounds.

CONCLUSION

This research might provide a deep view of tyrosinase inhibition by benzimidazole derivatives and a theoretical basis for developing albendazole as a potential fresh-keeping agent. © 2023 Society of Chemical Industry.

Possible Mechanisms of Oxidative Stress-Induced Skin Cellular Senescence, Inflammation, and Cancer and the Therapeutic Potential of Plant Polyphenols

As the greatest defense organ of the body, the skin is exposed to endogenous and external stressors that produce reactive oxygen species (ROS). When the antioxidant system of the body fails to eliminate ROS, oxidative stress is initiated, which results in skin cellular senescence, inflammation, and cancer. Two main possible mechanisms underlie oxidative stress-induced skin cellular senescence, inflammation, and cancer. One mechanism is that ROS directly degrade biological macromolecules, including proteins, DNA, and lipids, that are essential for cell metabolism, survival, and genetics. Another one is that ROS mediate signaling pathways, such as MAPK, JAK/STAT, PI3K/AKT/mTOR, NF-κB, Nrf2, and SIRT1/FOXO, affecting cytokine release and enzyme expression. As natural antioxidants, plant polyphenols are safe and exhibit a therapeutic potential. We here discuss in detail the therapeutic potential of selected polyphenolic compounds and outline relevant molecular targets. Polyphenols selected here for study according to their structural classification include curcumin, catechins, resveratrol, quercetin, ellagic acid, and procyanidins. Finally, the latest delivery of plant polyphenols to the skin (taking curcumin as an example) and the current status of clinical research are summarized, providing a theoretical foundation for future clinical research and the generation of new pharmaceuticals and cosmetics.

Arbutus unedo: Innovative Source of Antioxidant, Anti-Inflammatory and Anti-Tyrosinase Phenolics for Novel Cosmeceuticals

Phenolic compounds are valuable cosmetic ingredients. They display skin protective potential and play an important role in preserving cosmetic formulations due to their ability to neutralize free radicals. Considering this fact, the current study aims to obtain a phenolic-enriched fraction from Arbutus unedo for topical application in cosmeceutical products. The chemical composition and the antioxidant, anti-inflammatory, and anti-tyrosinase activities of different extracts from the plant were investigated and compared. Samples were obtained by maceration, reflux, and ultrasound using water and ethanol. The findings indicated that the extraction methods impacted the phytochemical composition of the extracts. The high-performance liquid chromatography with diode-array detection (HPLC–DAD) analysis showed a wide range of phenolic compounds, comprising phenolic acids and flavonoids. Among the extracts, the water reflux had significant levels of both total polyphenols, flavonoids, and tannins and possessed the most important content on hyperoside. It displayed the most significant antioxidant activities with high antiradical and reducing power, as well as strong total antioxidant activity. It possesses a promising whitening effect with high anti-tyrosinase activities. Furthermore, it shows no cytotoxicity and moderate anti-inflammatory activity. Finally, due to its high yield efficiency and activities, water reflux was selected to formulate a cosmeceutical oil-in-water nanoemulsion that displayed optimal pH and stability.

Ellagic acid activates the Keap1-Nrf2-ARE signaling pathway in improving Parkinson's disease: A review

Parkinson's disease (PD) is a familiar neurodegenerative disease, accompanied by motor retardation, static tremor, memory decline and dementia. Heredity, environment, age and oxidative stress have been suggested as key factors in the instigation of PD. The Keap1-Nrf2-ARE signaling is one of the most significant anti- oxidative stress (OS) pathways. The Keap1 is a negative regulator of the Nrf2. The Keap1-Nrf2-ARE pathway can induce cell oxidation resistance and reduce nerve injury to treat neurodegenerative diseases. Ellagic acid (EA) can inhibit the Keap1 to accumulate the Nrf2 in the nucleus, and act on the ARE to produce target proteins, which in turn may alleviate the impact of OS on neuronal cells of PD. This review analyzes the structure and physiological role of EA, along with the structure, composition and functions of the Keap1-Nrf2-ARE signaling pathway. We further expound on the mechanism of ellagic acid in its activation of the Keap1-Nrf2-ARE signaling pathway, as well as the relationship between EA in impairing the TLR4/Myd88/NF-κB and Nrf2 pathways. Ellagic acid has the potentiality of improving PD by activating the Keap1-Nrf2-ARE signaling pathway and scavenging free radicals.

Ellagic acid as a potent anticancer drug: A comprehensive review on in vitro, in vivo, in silico, and drug delivery studies

Ellagic acid as a polyphenol or micronutrient, which can be naturally found in different vegetables and fruits, has gained considerable attention for cancer therapy due to considerable biological activities and different molecular targets. Ellagic acid with low hydrolysis and lipophilic and hydrophobic nature is not able to be absorbed in circulation. So, accumulation inside the intestinal epithelial cells or metabolization to other urolithins leads to the limitation of direct evaluation of EA effects in clinical studies. This review focuses on the studies which supported anticancer activity of pure or fruit-extracted ellagic acid through in vitro, in vivo, in silico, and drug delivery methods. The results demonstrate ellagic acid modulates the expression of various genes incorporated in the cancer-related process of apoptosis and proliferation, inflammation related-gens, and oxidative-related genes. Moreover, the ellagic acid formulation in carriers composed of lipid, silica, chitosan, iron- bovine serum albumin nanoparticles obviously enhanced the stable release and confident delivery with minimum loss. Also, in silico analysis proved that ellagic acid was able to be placed at a position of cocrystal ADP, in the deep cavity of the protein target, and tightly interact with binding pocket residues leading to suppression of substrate availability of protein and its activation inhibition.

Natural products in cosmetics

The global cosmetics market reached US$500 billion in 2017 and is expected to exceed US$800 billion by 2023, at around a 7% annual growth rate. The cosmetics industry is emerging as one of the fastest-growing industries of the past decade. Data shows that the Chinese cosmetics market was US$60 billion in 2021. It is expected to be the world's number one consumer cosmetics market by 2050, with a size of approximately US$450 billion. The influence of social media and the internet has raised awareness of the risks associated with the usage of many chemicals in cosmetics and the health benefits of natural products derived from plants and other natural resources. As a result, the cosmetic industry is now paying more attention to natural products. The present review focus on the possible applications of natural products from various biological sources in skin care cosmetics, including topical care products, fragrances, moisturizers, UV protective, and anti-wrinkle products. In addition, the mechanisms of targets for evaluation of active ingredients in cosmetics and the possible benefits of these bioactive compounds in rejuvenation and health, and their potential role in cosmetics are also discussed.

The bioactivity and applications of pomegranate peel extract: A review

Pomegranate peel (PP) is a by-product in the processing of pomegranate products, which is usually discarded as a waste. However, a large number of researches have shown that pomegranate peel extract (PPE) is rich in a variety of phenolic substances, among which ellagic acid (EA), as one of the main active components, has significant biological activities, such as anti-oxidation, anti-tumor, anti-inflammatory, neuroprotection, anti-viral, and anti-bacterial. We analyzed the mechanism of EA's biological activity, and discussed its application in the food industry, for instance, food preservation, food additives, and functional foods. Combined with the research status of PPE, we discussed the limitations and development potential of PPE, in order to provide theoretical reference and scientific basis for the development and utilization of pomegranate by-products. PRACTICAL APPLICATIONS: Pomegranate peel (PP), the inedible part of the fruit, is usually treated as waste. In recent years, researchers have been committed to exploring various bioactive ingredients in PP and exploring its potential benefits to human health, which has far-reaching significance. In this paper, the chemical constituents of polyphenols in PP were reviewed, mainly focusing on the biological activity and mechanism of ellagic acid (EA). We reviewed the applications and invention patents of pomegranate peel extract (PPE) in food field, including food preservation, food additive, and functional foods, providing reference for the recycling and reuse of PP.

Effect of ascorbic acid on tyrosinase and its anti-browning activity in fresh-cut Fuji apple

Tyrosinase (polyphenol oxidase) is the key enzyme of enzymatic browning in fruits and vegetables. In this research, the impact of ascorbic acid on tyrosinase and its anti-browning effect on fresh-cut Fuji apple were investigated. Ascorbic acid had a dual effect on tyrosinase with a half inhibitory concentration (IC₅₀ ) of 13.40 ± 0.05 µM. Fluorescence assay demonstrated that ascorbic acid interacted with tyrosinase in a dynamic contaction caused by Förster's resonance energy transfer (FRET) and induced a conformational change of the enzyme. Thermodynamic analysis, copper interaction, and molecular docking further confirmed that ascorbic acid could chelate the copper ions located in active center and interact with amino acid residues of tyrosinase via hydrophobic interaction. In addition, ascorbic acid prevented the browning of fresh-cut apples by increasing APX activity and inhibiting PPO and POD activities which reduce the oxidation of total phenolics and flavonoids. PRACTICAL APPLICATIONS: The present study demonstrated that ascorbic acid had a strong inhibitory activity against tyrosinase (IC₅₀ = 13.40 ± 0.05 µM) and anti-browning activity against fresh-cut Fuji apple. It could delay the browning degree of apple juice, increase APX activity, inhibit PPO and POD activities, and reduce the oxidation of total phenolics and flavonoids. These findings provided a basis for the feasible application of ascorbic acid on the preservation of fruits.

Ellagic acid inhibits high glucose-induced injury in rat mesangial cells via the PI3K/Akt/FOXO3a signaling pathway

The pathological damage of mesangial cells serves an important role in the occurrence and development of diabetic nephropathy. Ellagic acid has been reported to possess antioxidant, antitumor, antiviral and anti-inflammatory properties in several diseases, but the roles of ellagic acid in diabetic nephropathy are unclear. The main aim of the present study was to investigate the effect of ellagic acid on high glucose-induced mesangial cell damage. The results revealed that high glucose could induce the hyperproliferation of mesangial cells, decrease the activity of superoxide dismutase, increase the malondialdehyde content, the level of reactive oxygen species, the secretion of inflammatory factors (TNF-α, IL-1β and IL-6) and the synthesis of extracellular matrix (Fibronectin, MMP-9 and TIMP-1) and activate the PI3K/Akt/FOXO3a signaling pathway. Ellagic acid could attenuate the injury of mesangial cells induced by high glucose in a concentration-dependent manner and its effect was consistent with that of a PI3K inhibitor (LY294002). Moreover, a PI3K agonist (740Y-P) reversed the protective effect of ellagic acid on mesangial cells induced by high glucose. In conclusion, ellagic acid protected mesangial cells from high glucose-induced injury in a concentration-dependent manner. The mechanism may be associated with ellagic acid inhibiting the activation of the PI3K/Akt signaling pathway and reducing the expression levels of downstream transcription factor FOXO3a.

Anti-polyphenol oxidase properties of total flavonoids from young loquat fruits: inhibitory activity and mechanism

This study investigated anti-polyphenol oxidase activity and mechanism of purified total flavonoids (PTF) from young loquat fruits. PTF remarkably inhibited the activity of polyphenol oxidase (PPO) with an IC₅₀ value of 21.03 ± 2.37 μg/mL. Based on enzyme kinetics, PTF was found to be a potent, mixed-type, and reversible inhibitor of PPO. The fluorescence intensity of PPO was quenched by PTF through forming a PTF-PPO complex in a static procedure. Therefore, this study authenticated PTF as an efficient PPO inhibitor, which would contribute to their utilization in food industry.