Furan inhibitory activity against tyrosinase and impact on B16F10 cell toxicity

Interaction of the extracellular protease from Staphylococcus xylosus with meat proteins elucidated via spectroscopic and molecular docking

This study aimed to assess the effect of an external protease secreted by Staphylococcus (S.) xylosus on the hydrolysis and flavor properties of meat protein. The results indicated that the protease significantly increased the solubility of myofibrillar proteins (MPs) and sarcoplasmic proteins (SPs) in water (P < 0.05), and altered their surface hydrophobicity and secondary structure. The results of micromorphological and free amino acids analyses suggested that the protease degraded the large and insoluble meat protein aggregates into small molecular proteins with uniform distribution and amino acids, especially glycine, glutamic acid, leucine, and cysteine. Moreover, the protease-catalyzed hydrolysis promoted the formation of some volatile compounds in the MPs and SPs. Additionally, molecular docking analysis suggested that hydrogen bond and hydrophobic interaction promoted the formation of a S. xylosus protease/meat protein complex. These results provided a basis for the future application of S. xylosus protease in meat products.

Inhibition of cinnamic acid and its derivatives on polyphenol oxidase: Effect of inhibitor carboxyl group and system pH

Phenolic acids are promising inhibitors of polyphenol oxidase (PPO), but the effects of carboxyl group and pH on their inhibition effects are still unclear. In this study, methyl cinnamate, cinnamic acid and 4-carboxycinnamic acid were investigated by their inhibitory effects with pH varied from 6.8 to 5.0. Results showed that 4-carboxycinnamic acid had the strongest inhibitory effect on PPO, followed by cinnamic acid and methyl cinnamate. Acidic pH enhanced the inhibitory effects of cinnamic acid and its derivatives on PPO, and the enhancement degree, IC50 and Ki declining degree were followed as 4-carboxycinnamic acid > cinnamic acid > methyl cinnamate. Methyl cinnamate exhibited competitive inhibition on PPO, while cinnamic acid and 4-carboxycinnamic acid exhibited mixed-type inhibition. Inhibitors induced slight changes in the secondary and tertiary structures of PPO, which were enhanced by acidic pH. Molecular docking results showed that 4-carboxycinnamic acid exhibited the strongest binding ability, and the main interaction forces were around carboxyl groups, and acidic pH enhanced the binding effect through more interactions and lower binding energy. This study could provide new insights into industrial application of cinnamic acid and its derivatives for the control of enzymatic browning of fruits and vegetables.

Targeting metabolic reprogramming in hepatocellular carcinoma to overcome therapeutic resistance: A comprehensive review

Hepatocellular carcinoma (HCC) poses a heavy burden on human health with high morbidity and mortality rates. Systematic therapy is crucial for advanced and mid-term HCC, but faces a significant challenge from therapeutic resistance, weakening drug effectiveness. Metabolic reprogramming has gained attention as a key contributor to therapeutic resistance. Cells change their metabolism to meet energy demands, adapt to growth needs, or resist environmental pressures. Understanding key enzyme expression patterns and metabolic pathway interactions is vital to comprehend HCC occurrence, development, and treatment resistance. Exploring metabolic enzyme reprogramming and pathways is essential to identify breakthrough points for HCC treatment. Targeting metabolic enzymes with inhibitors is key to addressing these points. Inhibitors, combined with systemic therapeutic drugs, can alleviate resistance, prolong overall survival for advanced HCC, and offer mid-term HCC patients a chance for radical resection. Advances in metabolic research methods, from genomics to metabolomics and cells to organoids, help build the HCC metabolic reprogramming network. Recent progress in biomaterials and nanotechnology impacts drug targeting and effectiveness, providing new solutions for systemic therapeutic drug resistance. This review focuses on metabolic enzyme changes, pathway interactions, enzyme inhibitors, research methods, and drug delivery targeting metabolic reprogramming, offering valuable references for metabolic approaches to HCC treatment.

Furan promotes cytotoxic effects through DNA damage and cell apoptosis in Leydig cells

Furan is an organic chemical that can cause adverse effects on human health and is formed as a result of the thermal decomposition of many food components during cooking, storage, and processing techniques. Studies have shown that exposure to furan causes nephrotoxicity, hepatotoxicity, immunotoxicity, and reproductive toxicity. According to our current knowledge of the literature, the genotoxic mode of action of furan is highly controversial. The genotoxic effects of furan on the male reproductive system, however, have not been studied. In this study, the TM3 Leydig cell line was treated with 750, 1500, and 3000 μM concentrations of furan for 24 h. Following the completion of the exposure period, the cytotoxicity of furan in TM3 Leydig cells was assessed using a cell viability assay and a spectrophotometric measurement of lactate dehydrogenase (LDH) enzyme levels. The double fluorescence staining method was used to demonstrate furan-induced apoptosis, and DNA damage was shown using the micronucleus, comet, and chromosomal aberration assays. The result indicated that furan administration of Leydig cells resulted in an increase in structural chromosomal aberration, comet, and micronucleus formation, reduced cell viability, increased LDH activity, and a higher incidence of apoptotic cells. These findings revealed that furan induces DNA damage in TM3 Leydig cells, causing genotoxicity and DNA damage-induced cytotoxicity.

Assessment of the oxidative damage and apoptotic pathway related to furan cytotoxicity in cultured mouse Leydig cells

Research on heat-induced food contamination is being given more attention as a result of the health risks that have been publicly revealed in recent years. Furan is known as a colorless, combustible, heterocyclic aromatic organic molecule and is formed when food products are processed and stored. It has been established that furan, which is inevitably ingested, has a deleterious impact on human health and causes toxicity. Furan is known to have adverse effects on the immune system, neurological system, skin, liver, kidney, and fat tissue. Infertility caused by furan is a result of its damaging effects on several tissues and organs as well as the reproductive system. Although studies on the adverse effects of furan on the male reproductive system have been performed, there is no study revealing apoptosis in Leydig cells at the gene level. In this study, TM3 mouse Leydig cells were exposed to 250- and 2,500-μM concentrations of furan for 24 h. The findings demonstrated that furan decreased cell viability and antioxidant enzyme activity while increasing lipid peroxidation, reactive oxygen species, and apoptotic cell rates. Furan also increased the expression of the important apoptotic genes Casp3 and Trp53 while decreasing the expression of another pro-apoptotic gene, Bcl2, and antioxidant genes Sod1, Gpx1, and Cat. In conclusion, these results imply that furan may cause loss of cell function in mouse Leydig cells responsible for testosterone biosynthesis by impairing the efficiency of the antioxidant system, possibly by inducing cytotoxicity, oxidative stress, and apoptosis.

Heterocyclic Compounds as Synthetic Tyrosinase Inhibitors: Recent Advances

Tyrosinase is a copper-containing enzyme which is widely distributed in nature (e.g., bacteria, mammals, fungi) and involved in two consecutive steps of melanin biosynthesis. In humans, an excessive production of melanin can determine hyperpigmentation disorders as well as neurodegenerative processes in Parkinson's disease. The development of molecules able to inhibit the high activity of the enzyme remain a current topic in medicinal chemistry, because the inhibitors reported so far present several side effects. Heterocycle-bearing molecules are largely diffuse in this sense. Due to their importance as biologically active compounds, we decided to report a comprehensive review of synthetic tyrosinase inhibitors possessing heterocyclic moieties reported within the last five years. For the reader's convenience, we classified them as inhibitors of mushroom tyrosinase (Agaricus bisporus) and human tyrosinase.

Effects of ultrasound treatment on muscle structure, volatile compounds, and small molecule metabolites of salted Culter alburnus fish

This study investigated the effects of ultrasound treatment on the quality of salted Culter alburnus fish. The results showed that with the increasing ultrasound power, the structural degradation of muscle fibers was intensified, and the conformation of myofibrillar protein was significantly changed. The high-power ultrasound treatment group (300 W) had relatively higher thiobarbiturate reactive substance content (0.37 mg malondialdehyde eq/kg) and peroxidation value (0.63 mmol/kg). A total of 66 volatile compounds were identified with obvious differences among groups. The 200 W ultrasound group exhibited fewer fishy substances (Hexanal, 1-Pentene-3-ol, and 1-Octane-3-ol). Compared with control group, ultrasound groups (200, 300 W) contained more umami taste-related amino peptides such as γ-Glu-Met, γ-Glu-Ala, and Asn-pro. In the ultrasound treatment group, L-isoleucine and L-methionine, which may be used as flavor precursors, were significantly down-regulated, while carbohydrates and its metabolites were up-regulated. Amino acid, carbohydrate, and FA (fatty acyls) metabolism products in salted fish were enriched by ultrasound treatment, and those products might ultimately be related to the taste and flavor of salted fish.

Theoretical study on the degradation mechanism, kinetics and toxicity for aqueous ozonation reaction of furan derivatives

The compounds including Furan-2,5-dicarboxylic acid (FDCA), 2-methyl-3-furoic acid (MFA), and 2-furoic acid (FA), containing Furan rings are considered to be possessing high ozone reactivity, although in depth studies of their ozonation processes have not been carried out yet. Hence, mechanism, kinetics and toxicity by quantum chemical, and their structure activity relationship are being investigated in this study. Studies of reaction mechanisms revealed that during the ozonolysis of three furan derivatives containing C=C double bond, furan ring opening occurs. At temperature (298 K) and pressure of 1 atm the degradations rates of 2.22 × 10³ M^-1 s^-1 (FDCA), 5.81 × 10⁶ M^-1 s^-1 (MFA) and 1.22 × 10⁵ M^-1 s^-1 (FA) suggested that the reactivity order is: MFA > FA > FDCA. In the presence of water, oxygen and ozone, the primary product of ozonation, the Criegee intermediates (CIs) would produce lower molecule weight of aldehydes and carboxylic acids by undergoing degradation pathways. The aquatic toxicity reveals that three furan derivatives play green chemicals roles. Significantly, most of degradation products are least harmful to organisms residing the hydrosphere. The mutagenicity and developmental toxicity of FDCA is minimum as compared to FA and MFA, which shows the applicability of FDCA in a wider and broader field. Results of this study revealed its importance in the industrial sector and degradation experiments.

Control of Beany Flavor from Soybean Protein Raw Material in Plant-Based Meat Analog Processing

The development of plant-based meat analogs is currently hindered by the beany flavor generated by raw soybean protein and extrusion processing. Wide concern has led to extensive research on the generation and control of this unwanted flavor, as an understanding of its formation in raw protein and extrusion processing and methods through which to control its retention and release are of great significance for obtaining ideal flavor and maximizing food quality. This study examines the formation of beany flavor during extrusion processing as well as the influence of interaction between soybean protein and beany flavor compounds on the retention and release of the undesirable flavor. This paper discusses ways to maximize control over the formation of beany flavor during the drying and storage of raw materials and methods to reduce beany flavor in products by adjusting extrusion parameters. The degree of interaction between soybean protein and beany compounds was found to be dependent on conditions such as heat treatment and ultrasonic treatment. Finally, future research directions are proposed and prospected. This paper thus provides a reference for the control of beany flavor during the processing, storage, and extrusion of soybean raw materials used in the fast-growing plant-based meat analog industry.

Ultrasonic-Assisted Synthesis of Benzofuran Appended Oxadiazole Molecules as Tyrosinase Inhibitors: Mechanistic Approach through Enzyme Inhibition, Molecular Docking, Chemoinformatics, ADMET and Drug-Likeness Studies

Furan-oxadiazole structural hybrids belong to the most promising and biologically active classes of oxygen and nitrogen containing five member heterocycles which have expanded therapeutic scope and potential in the fields of pharmacology, medicinal chemistry and pharmaceutics. A novel series 5a-j of benzofuran-oxadiazole molecules incorporating S-alkylated amide linkage have been synthesized using ultrasonic irradiation and screened for bacterial tyrosinase inhibition activity. Most of the synthesized furan-oxadiazole structural motifs exhibited significant tyrosinase inhibition activity in the micromolar range, with one of the derivatives being more potent than the standard drug ascorbic acid. Among the tested compounds, the scaffold 5a displayed more tyrosinase inhibition efficacy IC₅₀ (11 ± 0.25 μM) than the ascorbic acid IC₅₀ (11.5 ± 0.1 μM). Compounds 5b, 5c and 5d efficiently inhibited bacterial tyrosinase with IC₅₀ values in the range of 12.4 ± 0.0-15.5 ± 0.0 μM. The 2-fluorophenylacetamide containing furan-oxadiazole compound 5a may be considered as a potential lead for tyrosinase inhibition with lesser side effects as a skin whitening and malignant melanoma anticancer agent.

The Luteolinidin and Petunidin 3-O-Glucoside: A Competitive Inhibitor of Tyrosinase

The enzyme tyrosinase plays a key role in the early stages of melanin biosynthesis. This study evaluated the inhibitory activity of anthocyanidin (1) and anthocyanins (2-6) on the catalytic reaction. Of the six derivatives examined, 1-3 showed inhibitory activity with IC₅₀ values of 3.7 ± 0.1, 10.3 ± 1.0, and 41.3 ± 3.2 μM, respectively. Based on enzyme kinetics, 1-3 were confirmed to be competitive inhibitors with K_i values of 2.8, 9.0, and 51.9 μM, respectively. Molecular docking analysis revealed the formation of a binary encounter complex between 1-3 and the tyrosinase catalytic site. Luteolinidin (1) and petunidin 3-O-glucoside (2) may serve as tyrosinase inhibitors to block melanin production.

Tyrosinase inhibitory mechanism and the anti-browning properties of piceid and its ester

Different mechanisms for inhibiting tyrosinase can be exploited to avoid quality losses caused by the enzymatic browning of fruits and vegetables. Piceid (PI) and piceid 6″-O- azelaic acid ester (PIA) are oxidized by tyrosinase; however, their oxidation products may have inhibitory effects on tyrosinase. This notion is because l-DOPA oxidation was inhibited after the pre-incubation of PI/PIA with tyrosinase, however, l-DOPA oxidation was not affected if this pre-incubation was not performed. Circular dichroism analysis indicated a conformational change in the secondary structure of tyrosinase after pre-incubation. Further, molecular docking and enzyme reaction kinetics assays were employed to reveal the mechanism underlying the effects of PI/PIA on tyrosinase in the absence of pre-incubation with tyrosinase. PI/PIA had anti-browning effects in the potato models. The increased rate of A₄₂₀ in PI/PIA groups at 24 h were 281% and 279%, which were approximately 2.4- and 2.5-fold lower than that of control (668%).

Tyrosinase inhibition by novel benzimidazole-thione Schiff base derivatives

Background:

Tyrosinase is the enzyme responsible for the conversion of tyrosine to dopaquinone, which is related to melanoma, neurodegenerative disorders, freckles, pigmented acne and age spots. Controlling the tyrosinase activity could be an important way for treating overproduction of melanin.

Objective:

The development of safe and specific tyrosinase inhibitors could be used to treat hypermelanosis.

Methods:

5-nitro-1H-benzo[d]imidazole-2(3H)-thione was synthesized from 4-nitro-o-phenylenediamine and carbon disulfide. The nitro group of 5-nitro-1H- S-1 ESI-HRMS benzo[d]imidazole-2(3H)-thione was reduced with iron powder. The 5-amino-1H-benzo[d]imidazole- 2(3H)-thione Schiff base derivatives were obtained by the reaction of 5-amino-1H-benzo[d]imidazole-2(3H)-thione with substituted benzaldehyde. The tyrosinase inhibitory activities were investigated. The studies of kinetic analysis, metal-chelating properties, docking and cytotoxicity were also performed.

Results:

All of the compounds showed strong tyrosinase inhibitory activities with 5-((4-nitrobenzylidene) amino)-1H-benzo [d]imidazole-2(3H)-thione (S-4) as the best tyrosinase inhibitor with an IC50 value of 4.8 ± 1.4 nM. Compound S-4 exhibited mixed type inhibition of mushroom tyrosinase, with Ki 15 nM and Kis 42 nM. Copper binding to S-4 was detected spectrophotometrically and 1-100 ìÌ S-4 displayed negligible cytotoxicity to murine B16 melanoma cells.

Conclusion:

Our results demonstrated that these benzimidazolethione Schiff base derivatives might be promising candidates as tyrosinase inhibitors.

Drying methods influence the physicochemical and functional properties of seed-used pumpkin

The effects of far-infrared radiation drying (FIRD), freeze drying (FD), vacuum drying (VD), and hot air drying (HAD) on appearance, physicochemical properties, antioxidant activities, antityrosinase capacity using B16F10 melanoma cell from seed-used pumpkins (hull-less pumpkin and hull pumpkin) were evaluated. Results suggested that hull-less pumpkin (HLP) dehydrated by FIRD provided the highest total polyphenols content (37.11 ± 1.05 mg GAE/ g DW) and the ability of scavenging free radicals. HPLC analysis exhibited that coumaric acid was predominant phenolic acid in pumpkin. The correlation analysis demonstrated that polyphenolic compounds were related to antioxidant capacity. HLP-FD possessed better colour, higher preservation of β-carotene, ascorbic acid and higher sugar contents compared with HLP-HAD. The highest antityrosinase activity was recorded in HLP-VD with a concentration of 37.16%. The melanin inhibition increased to 76.61%, and intracellular tyrosinase activity in B16F10 melanoma cells decreased to 88.63% at 800 μg/mL of polyphenol extract.

Inhibitory mechanism of two homoisoflavonoids from Ophiopogon japonicus on tyrosinase activity: insight from spectroscopic analysis and molecular docking

The inhibition mechanism of two homoisoflavonoids from Ophiopogon japonicus including methylophiopogonanone A (MO-A) and methylophiopogonanone B (MO-B) on tyrosinase (Tyr) was studied by multiple spectroscopic techniques and molecular docking. The results showed that the two homoisoflavonoids both inhibited Tyr activity via a reversible mixed-inhibition, with a half inhibitory concentration (IC50) of (10.87 ± 0.25) × 10-5 and (18.76 ± 0.14) × 10-5 mol L-1, respectively. The fluorescence quenching and secondary structure change of Tyr caused by MO-A and B are mainly driven by hydrophobic interaction and hydrogen bonding. Molecular docking analysis indicated that phenylmalandioxin in MO-A and methoxy in MO-B could coordinate with a Cu ion in the active center of Tyr, and interacted with amino acid Glu322 to form hydrogen bonding, occupying the catalytic center to block the entry of the substrate and consequently inhibit Tyr activity. This study may provide new perspectives on the inhibition mechanism of MO-A and MO-B on Tyr and serve a scientific basis for screening effective Tyr inhibitors.

Efficient tyrosinase nano-inhibitor based on carbon dots behaving as a gathering of hydrophobic cores and key chemical group

Small organic molecules have been extensively applied to achieve enzymatic inhibition. Although numerous efforts have been made to deliver efficient inhibitors, small inhibitors applications are hindered by many drawbacks. Moreover, reporters comprising nanoparticle inhibitory activity against enzymes are very scarce in the literature. In this scenario, carbon nanodots (CDs) emerge as promising candidates for efficient enzyme inhibition due to their unique properties. Here, CDs specific molecular characteristics (core composition and chemical surface groups) have been investigated to produce a more potent enzyme inhibition. Mushroom tyrosinase (mTyr) has been adopted as an enzymatic prototype. The CDs revealed a high affinity to mTyr (Ka ≈ 10⁶ M^-1), mainly through hydrophobic forces and followed by slight mTyr structural alteration. CDs competitively inhibit mTyr, with low inhibition constant (K_I = 517.7 ± 17.0 nM), which is up 70 fold smaller then the commercial inhibitor (kojic acid) and the starch nanoparticles previously reported. The results expose that the CDs act as a hydrophobic agglomerate with carboxyl groups on its surface, mimicking characteristics found on small molecule inhibitors (but with superior performance). All these results highlight the CD excellent potential as an efficient low toxic Tyr inhibitor, opening the prospect of using these nanoparticles in the cosmetic and food industries.

Fluorescence copolymer-based dual-signal monitoring tyrosinase activity and its inhibitor screening via blue-green emission transformation

Tyrosinase (TYR) is a crucial enzyme in melanin metabolism and catecholamine production, its abnormal overexpression is closely associated with many human diseases involving melanoma cancer, vitiligo, Parkinson's disease and so on. Herein, a dual-signal fluorescence sensing system for monitoring TYR activity is constructed depending on the transformation of blue-green fluorescence emission of copolymer. The developed sensing system is based on TYR catalyzing the hydroxylation of mono-phenol to o-diphenol and the conversion of fluorescence copolymer (FCP) blue emission (430 nm) and green emission (535 nm) in the presence of PEI. In the system, both blue and green emission exhibit a high selectivity and sensitivity (S/B up to 300 and 30 for blue and green emission, respectively) toward TYR in the range from 0.5 to 2.5 U/mL with the detection limit of 0.002 U/mL and 0.06 U/mL, respectively. Additionally, this assay is used to detect TYR in human serum with excellent recovery even at 30% human serum concentrations. Furthermore, it still has been successfully applied to TYR inhibitor screening by taking kojic acid as a model. We believe that our developed sensor has great potential application in TYR-associated disease diagnosis and treatment and drug discovery.

(E)-1-(Furan-2-yl)-(substituted phenyl)prop-2-en-1-one Derivatives as Tyrosinase Inhibitors and Melanogenesis Inhibition: An In Vitro and In Silico Study

A series of (E)-1-(furan-2-yl)prop-2-en-1-one derivatives (compounds 1–8) were synthesized and evaluated for their mushroom tyrosinase inhibitory activity. Among these series, compound 8 (2,4-dihydroxy group bearing benzylidene) showed potent tyrosinase inhibitory activity, with respective IC₅₀ values of 0.0433 µM and 0.28 µM for the monophenolase and diphenolase as substrates in comparison to kojic acid as standard compound 19.97 µM and 33.47 µM. Moreover, the enzyme kinetics of compound 8 were determined to be of the mixed inhibition type and inhibition constant (K_i) values of 0.012 µM and 0.165 µM using the Lineweaver-Burk plot. Molecular docking results indicated that compound 8 can bind to the catalytic and allosteric sites 1 and 2 of tyrosinase to inhibit enzyme activity. The computational molecular dynamics analysis further revealed that compound 8 interacted with two residues in the tyrosinase active site pocket, such as ASN260 and MET280. In addition, compound 8 attenuated melanin synthesis and cellular tyrosinase activity, simulated by α-melanocyte-stimulating hormone and 1-methyl-3-isobutylxanthine. Compound 8 also decreased tyrosinase expressions in B16F10 cells. Based on in vitro and computational studies, we propose that compound 8 might be a worthy candidate for the development of an antipigmentation agent.

A new lectin from the floral capitula of Egletes viscosa (EgviL): Biochemical and biophysical characterization and cytotoxicity to human cancer cells

Egletes viscosa is a plant with therapeutic value due to its antibacterial, antinociceptive and gastroprotective properties. This study aimed to purify, characterize, and evaluate the cytotoxicity of a lectin (EgviL) from the floral capitula of E. viscosa. The lectin was isolated from saline extract through precipitation with ammonium sulfate followed by Sephadex G-75 chromatography. The molecular mass and isoelectric point (pI) of EgviL were determined as well as its temperature and pH stability. Physical-chemical parameters of interaction between EgviL and carbohydrates were investigated by fluorescence quenching and ¹H nuclear magnetic resonance (NMR). Cytotoxicity was investigated against human peripheral blood mononuclear cells (PBMCs) and neoplastic cells. EgviL (28.8 kDa, pI 5.4) showed hemagglutinating activity stable towards heating until 60 °C and at the pH range 5.0-7.0. This lectin is able to interact through hydrophobic and electrostatic bonds with galactose and glucose, respectively. EgviL reduced the viability of PBMCs only at the highest concentration tested (100 μg/mL) while was toxic to Jurkat E6-1 cells with IC₅₀ of 24.1 μg/mL,inducing apoptosis. In summary, EgviL is a galactose/glucose-binding protein with acidic character, stable to heating and with cytotoxic effect on leukemic cells.

Crystal structure of N'-[4-(di-methyl-amino)-benzyl-idene]furan-2-carbohydrazide monohydrate

The condensation of 2-furoic hydrazide and 4-dimethyl amino-benzaldehyde in ethanol yielded a yellow solid formulated as the title compound, C14H15N3O2·H2O. The crystal packing is stabilized by inter-molecular O(water)-H⋯O,N(carbohydrazide) and N-H⋯O(water) hydrogen bonds, which form a two-dimensional network along the bc plane. Additional C-H⋯O inter-actions link the mol-ecules into a three-dimensional network. The dihedral angle between the mean planes of the benzene and the furan ring is 34.47 (6)°. The carbohydrazide moiety, i.e., the C=N-N-C=O fragment and the benzene ring are almost coplanar, with an angle of 6.75 (9)° between their mean planes.

In Vitro Enzyme Inhibitory Properties, Secondary Metabolite Profiles and Multivariate Analysis of Five Seaweeds

Seaweeds have been exploited as both food products and therapeutics to manage human ailments for centuries. This study investigated the metabolite profile of five seaweeds (Halimeda spp., Spyridia hypnoides (Bory de Saint-Vincent) Papenfuss, Valoniopsis pachynema (G. Martens) Børgesen, Gracilaria fergusonii J. Agardh and Amphiroa anceps (Lamarck) Decaisne using ultra-high-performance liquid chromatography coupled with electrospray ionization mass spectrometry (UHPLC-ESI-MS/MS). Furthermore, these seaweeds were assessed for antioxidant and inhibitory effects against α-amylase, α-glucosidase, acetyl-cholinesterase (AChE), butyryl-cholinesterase (BChE) and tyrosinase. Valoniopsis pachynema and A. anceps yielded the highest flavonoid (4.30 ± 0.29 mg RE/g) and phenolic content (7.83 ± 0.08 mg RE/g), respectively. Additionally, A. anceps exhibited significant antioxidant properties with all assays and significantly depressed BChE (IC₅₀ = 6.68 ± 0.83 mg/mL) and α-amylase activities (IC₅₀ = 5.34 ± 0.14 mg/mL). Interestingly, the five seaweeds revealed potent inhibitory effects against tyrosinase activity. In conclusion, A. anceps might be considered as a key source of phytoantioxidants and a potential candidate to develop nutritional supplements. Besides, the five tested seaweeds warrant further study and may be exploited as promising natural sources for managing hyperpigmentation.

Inhibitory mechanism of epicatechin gallate on tyrosinase: inhibitory interaction, conformational change and computational simulation

Epicatechin gallate can inhibit the activity of tyrosinase in a mixed-type manner.