Insights on the Inhibitory Power of Flavonoids on Tyrosinase Activity: A Survey from 2016 to 2021

Chemometric discrimination of eight citrus plants utilizing chromatographic and spectroscopic techniques and insights into their biological potentials

Citrus sinensis balady orange, C. sinensis navel orange, C. paradisi, C. limon, C. sinensis bloody orange, C. sinensis sweet orange, C. aurantium var. amara and C. reticulata were successfully discriminated using chromatographic and spectroscopic techniques coupled with chemometrics. Ultraviolet spectroscopy (UV), and nuclear magnetic resonance spectroscopy (NMR) managed to discriminate the alcohol extract samples to six and five clusters respectively on exposing the obtained data to Principle component analysis (PCA). High performance liquid chromatography (HPLC) was utilized for differentiating the different samples based upon their rutin content where C. aurantium demonstrated the highest rutin content (0.795 mg/mL). LC-ESI-MS led to the identification of 35 compounds belonging mainly to flavonoids and limonoids. In vitro biological investigations including DDPH, ABTS, FRAP and enzyme inhibitory activities revealed the promising antioxidant, neuroprotective, anti-hyperglycaemic and skin-lightning potentials of citrus samples that were correlated with the total phenol and flavonoid contents. In silico ADME/TOPKAT reflected the acceptable pharmacokinetic, pharmacodynamic and toxicity properties of the identified secondary metabolites.

Antimicrobial, Antioxidant, and Antityrosinase Activities of Morina persica L. and Its Isolated Compounds

In this study, the isolation of compounds from the aerial parts of Morina persica L. and the antimicrobial, antioxidant and antityrosinase activities of various polarity extracts and isolated compounds were investigated. Column chromatography methods were used for isolation. A microdilution method was used to determine antimicrobial activity; Folin-Ciocalteu method was used to determine total phenolic content; DPPH and ABTS radical scavenging- capacity methods were used to determine antioxidant activity; and a mushroom tyrosinase method was used to determine antityrosinase activity. Kaempferol-3-O-β-glucopyranoside (astragalin) and quercetin-3-O-rutinoside (rutin) were isolated from M. persica. The extracts and compounds showed higher activity against Staphylococcus aureus and Enterococcus faecalis than other tested bacteria. The highest phenolic content, DPPH, and ABTS radical scavenging activity were detected in an ethyl acetate extract at 50 μg/mL concentration. The methanol extract showed the highest antityrosinase effect at 200 μg/mL concentration.

Combining chemical profiles and biological abilities of different extracts from Tanacetum nitens ( Boiss. & Noë) Grierson using network pharmacology

Tanacetum nitens ( Boiss. & Noë)  Grierson is an aromatic perennial herb used in Turkish traditional medicine to treat headache, fever, and skin diseases. This study aimed to investigate the chemical composition, antioxidant, enzyme inhibition, and cytotoxic properties of T. nitens aerial parts. Organic solvent extracts were prepared by sequential maceration in hexane, dichloromethane, ethyl acetate, and methanol while aqueous extracts were obtained by maceration or infusion. Nuclear magnetic resonance (NMR) and LC-DAD-MS analysis allowed the identification and quantification of different phytoconstituents including parthenolide, tanacetol B, tatridin B, quinic acid derivatives, β-sitosterol, and glycoside derivatives of quercetin and luteolin. The type and amount of these phytochemicals recovered by each solvent were variable and significant enough to impact the biological activities of the plant. Methanolic and aqueous extracts displayed the highest scavenging and ions-reducing properties while the dichloromethane and ethyl acetate extracts exerted the best total antioxidant activity and metal chelating power. Results of enzyme inhibition activity showed that the hexane, ethyl acetate, and dichloromethane extracts had comparable anti-acetylcholinesterase activity and the latter extract revealed the highest anti-butyrylcholinesterase activity. The best α-amylase and α-glucosidase inhibition activities were obtained from the hexane extract. The dichloromethane and ethyl acetate extracts exhibited the highest cytotoxic effect against the prostate carcinoma DU-145 cells. In conclusion, these findings indicated that T. nitens can be a promising source of biomolecules with potential therapeutic applications.

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.

Exploring the Phytochemical Composition and the Bioactive Properties of Malbec and Torrontés Wine Pomaces from the Calchaquíes Valleys (Argentina) for Their Sustainable Exploitation

Hydroalcoholic extracts from Malbec and Torrontés wine pomaces (Vitis vinifera L.) originating from the high-altitude vineyards of Argentina's Calchaquí Valleys were characterized. Total phenolics, hydroxycinnamic acids, orthodiphenols, anthocyanins, non-flavonoid phenolics, total flavonoids, flavones/flavonols, flavanones/dihydroflavonols, and tannins were quantified through spectrophotometric methods, with the Malbec extract exhibiting higher concentrations in most of phytochemical groups when compared to Torrontés. HPLC-DAD identified more than 30 phenolic compounds in both extracts. Malbec displayed superior antiradical activity (ABTS cation, nitric oxide, and superoxide anion radicals), reduction power (iron, copper, and phosphomolybdenum), hypochlorite scavenging, and iron chelating ability compared to Torrontés. The cytotoxicity assessments revealed that Torrontés affected the viability of HT29-MTX and Caco-2 colon cancer cells by 70% and 50%, respectively, at the highest tested concentration (1 mg/mL). At the same time, both extracts did not demonstrate acute toxicity in Artemia salina or in red blood cell assays at 500 µg/mL. Both extracts inhibited the lipoxygenase enzyme (IC50: 154.7 and 784.7 µg/mL for Malbec and Torrontés), with Malbec also reducing the tyrosinase activity (IC50: 89.9 µg/mL), and neither inhibited the xanthine oxidase. The substantial phenolic content and diverse biological activities in the Calchaquí Valleys' pomaces underline their potentialities to be valorized for pharmaceutical, cosmetic, and food industries.

Exploring Chemical Composition, Antioxidant, Enzyme Inhibitory and Cytotoxic Properties of Glaucium acutidentatum Hausskn. & Bornm. from Turkey Flora: A Novel Source of Bioactive Agents to Design Functional Applications

The present study was performed to determine the chemical constituents, cytotoxicity, antioxidant and enzyme inhibition activities of the aerial parts of Glaucium acutidentatum Hausskn. and Bornm. (family Papaveraceae). Methanolic and aqueous extracts were prepared by maceration, homogenizer-assisted extraction (HAE) and infusion. Results showed that the highest total phenolic and flavonoids contents were obtained from the methanol extracts obtained by HAE (53.22 ± 0.10 mg GAE/g) and maceration (30.28 ± 0.51 mg RE/g), respectively. The aporphine, beznyltetrahydroisoquinoline, and protopine types of Glaucium alkaloids have been tentatively identified. Among them, glaucine was identified in all extracts. Flavonoids, phenolic acids, coumarins, organic acids and fatty acids were also detected. Methanolic extract obtained using the HAE method displayed the highest anti-DPPH (41.42 ± 0.62 mg TE/g), total antioxidant (1.20 ± 0.17 mmol TE/g), Cu2+ (113.55 ± 6.44 mg TE/g), and Fe3+ (74.52 ± 4.74 mg TE/g) reducing properties. The aqueous extracts obtained by infusion and HAE methods exerted the best anti-ABTS (103.59 ± 1.49 mg TE/g) and chelating (19.81 ± 0.05 mg EDTAE/g) activities, respectively. Methanolic extract from HAE recorded the highest acetylcholinesterase (2.55 ± 0.10 mg GALAE/g) and α-amylase (0.51 ± 0.02 mmol ACAE/g) inhibition activities, while that obtained by maceration showed the best butyrylcholinesterase (3.76 ± 0.31 mg GALAE/g) inhibition activity. Both extracts revealed the best tyrosinase inhibitory activity (25.15 ± 1.00 and 26.79 ± 2.36 mg KAE/g, p ≥ 0.05). G. acutidentatum maceration-derived aqueous extract showed selective anticancer activity against cells originating from human hypopharyngeal carcinoma. In conclusion, these findings indicated that G. acutidentatum is a promising source of alkaloids and phenolic compounds for variable pharmaceutical formulations.

Chemical Profiling and Enzyme Inhibitory Activities of Essential Oil Isolated from Pistacia khinjuk Leaves: Insights On GC-MS Analysis and Skin Aging-Relevant Enzymes

Pistacia khinjuk is a species of flowering plants belonging to family Anacardiaceae, with promising pharmacological activities like antioxidants, anti-inflammatory, antiviral, and antimicrobial. This study aimed to investigate the GC-MS chemical composition of essential oil isolated from Pistacia khinjuk leaves and its inhibitory properties against aging-relevant enzymes such a collagenase and elastase. The isolated oil showed predominance of β-cadinene (15.34 %), γ-amorphene (8.50 %), α-cadinol (8.14 %), τ-cadinol (7.57 %), (E)-β-caryophyllene (5.77 %), α-pinene (4.70 %), phytol (4.57 %), α-muurolene (3.30 %), (+)-epi-bicyclosesquiphellandrene (3.21 %), and cubenene (3.16 %). Further, it showed remarkable inhibitory activities against collagenase and elastase with IC50 values of 15.61±0.69 and 41.12±2.09 μg/mL, respectively compared to epigallocatechin gallate (IC50=29.52±1.3 μg/mL and 26.86±1.37 μg/mL). as a conclusion, the leaf oil is recommended for topical cosmetic preparations to retard skin aging symptoms such as wrinkles. However, the bioavailability assessment and toxicological profile should be considered in the future studies.

Phytochemical analysis and biological investigation of Cheilanthes tenuifolia (Burm.f.) Swartz

Introduction: Cheilanthes tenuifolia is an evergreen ornamental small fern, belonging to the family Pteridaceae, that grows in warm and rocky regions worldwide. Many species of Cheilanthes genus are evidently endowed with important phytochemicals and bioactivities. This study aimed to perform a preliminary phytochemical analysis of Cheilanthes tenuifolia leaves alongside an evaluation of free radical scavenging, anti-inflammatory, antimicrobial, and clot lysis activities of extract fractions. Materials and methods: A preliminary phytochemical analysis was done after fractionation of ethanolic extract (ECT) with n-hexane (HCT) and chloroform (CCT). Then, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, egg albumin and RBC membrane stabilization tests, disc diffusion, and human blood clot lysis assays were performed. Results: Phytochemical investigations suggested that the plant is rich in alkaloids, glycosides, tannins, and flavonoids. All obtained fractions exhibited concentration-dependent radical scavenging, inhibition of egg protein denaturation and RBC membrane lysis capacities. Except for antifungal tests, ECT exhibited better DPPH radical scavenging, anti-inflammatory, antibacterial, and clot lysis capacities than HCT and CCT fractions. However, all fractions exhibited a mild anti-inflammatory activity. Conclusion: C. tenuifolia might be a good source of antioxidant, anti-microbial, and anti-atherothrombotic agents. Further studies are required to isolate and characterize the active principles liable for each bioactivity, along with possible molecular interactions.

Chemical characterization of three different extracts obtained from Chelidonium majus L. (Greater celandine) with insights into their in vitro, in silico and network pharmacological properties

Plant species C. majus, which is a very rich source of secondary metabolites, was used to obtain extracts, using a conventional extraction technique. For the extraction of bioactive molecules, three solvents were used: ethyl acetate, methanol and water, which differ from each other based on their polarity. The obtained extracts were examined in terms of chemical composition, antioxidant, enzyme inhibitory activity, and cytotoxic effects. The research results indicate that methanol was a better and more efficient extractant in the process of isolating bioactive compounds than ethyl acetate and water. The chemical composition of this solvent, i.e. its polarity, contributed the most to the extraction of alkaloids and flavonoids. The high content of total phenolic compounds in the methanol extract, as well as individual alkaloids, caused a very strong antioxidant activity, as well as a strong inhibitory power when it comes to inhibiting the excessive activity of cholinesterase and tyrosinase. Methanol and ethyl acetate extracts achieved very good cytotoxic activity against cancerous cells HGC-27 and HT-29 and did not exert a toxic effect on non-cancerous cell lines (HEK293). Extracts of plant species C. majus, especially methanol extract could be characterized as a very good starting plant material for the formulation of products intended for various branches of the food and pharmaceutical industry.

Development of chemometric-assisted supercritical fluid extraction of effective and natural tyrosinase inhibitor from Syzygium aqueum leaves

Tyrosinase is a key enzyme in enzymatic browning, causing quality losses in food through the oxidation process. Thus, the discovery of an effective and natural tyrosinase inhibitor via green technology is of great interest to the global food market due to food security and climate change issues. In this study, Syzygium aqueum (S. aqueum) leaves, which are known to be rich in phenolic compounds (PC), were chosen as a natural source of tyrosinase inhibitor, and the effect of the sustainable, supercritical fluid extraction (SFE) process was evaluated. Response surface methodology-assisted supercritical fluid extraction (RSM-assisted SFE) was utilized to optimize the PCs extracted from S. aqueum. The highest amount of PC was obtained at the optimum conditions (55 °C, 3350 psi, and 70 min). The IC50 (661.815 μg/mL) of the optimized extract was evaluated, and its antioxidant activity (96.8 %) was determined. Gas chromatography-mass spectrometry (GC-MS) results reveal that 2',6'-dihydroxy-4'-methoxychalcone (2,6-D4MC) (82.65 %) was the major PC in S. aqueum. Chemometric analysis indicated that 2,6-D4MC has similar chemical properties to the tyrosinase inhibitor control (kaempferol). The toxicity and physiochemical properties of the novel 2,6-D4MC from S. aqueum revealed that the 2,6-D4MC is safer than kaempferol as predicted via absorption, distribution, metabolism, and excretion (ADME) evaluation. Enzyme kinetic analysis shows that the type of inhibition of the optimized extract is non-competitive inhibition with Km = 1.55 mM and Vmax = 0.017 μM/s. High-performance liquid chromatography (HPLC) analysis shows the effectiveness of S. aqueum as a tyrosinase inhibitor. The mechanistic insight of the tyrosinase inhibition using 2,6-D4MC was successfully calculated using density functional theory (DFT) and molecular docking approaches. The findings could have a significant impact on food security development by devising a sustainable and effective tyrosinase inhibitor from waste by-products that is aligned with the United Nation's SDG 2, zero hunger.

The possible role of nuclear factor erythroid-2-related factor 2 activators in the management of Covid-19

COVID-19 is caused by a novel SARS-CoV-2 leading to pulmonary and extra-pulmonary manifestations due to oxidative stress (OS) development and hyperinflammation. COVID-19 is primarily asymptomatic though it may cause acute lung injury (ALI), acute respiratory distress syndrome (ARDS), systemic inflammation, and thrombotic events in severe cases. SARS-CoV-2-induced OS triggers the activation of different signaling pathways, which counterbalances this complication. One of these pathways is nuclear factor erythroid 2-related factor 2 (Nrf2), which induces a series of cellular interactions to mitigate SARS-CoV-2-mediated viral toxicity and OS-induced cellular injury. Nrf2 pathway inhibits the expression of pro-inflammatory cytokines and the development of cytokine storm in COVID-19. Therefore, Nrf2 activators may play an essential role in reducing SARS-CoV-2 infection-induced inflammation by suppressing NLRP3 inflammasome in COVID-19. Furthermore, Nrf2 activators can attenuate endothelial dysfunction (ED), renin-angiotensin system (RAS) dysregulation, immune thrombosis, and coagulopathy. Thus this mini-review tries to clarify the possible role of the Nrf2 activators in the management of COVID-19. Nrf2 activators could be an effective therapeutic strategy in the management of Covid-19. Preclinical and clinical studies are recommended in this regard.

Investigation on the inhibition mechanism and binding behavior of paeonol to tyrosinase and its anti-browning property by multi-spectroscopic and molecular docking methods

Paeonol, as one effective tyrosinase inhibitor, had been used as food preservative and clinical medication for skin disorders. In this study, the inhibition mechanism and binding behavior of paeonol to tyrosinase and its anti-browning property were investigated using multi-spectroscopic and molecular docking methods. Activity assay and kinetic results confirmed paeonol as a reversible mixed-type tyrosinase inhibitor. Results of the mechanistic studies were clarified using fluorescence quenching, synchronous fluorescence, CD spectra and 3D fluorescence, and showed that the binding of paeonol to tyrosinase might change the chromophore microenvironment and conformation of tyrosinase to inhibit enzyme catalytic activity. Molecular docking results revealed the detailed binding between paeonol and tyrosinase. Moreover, paeonol could prevent the browning of fresh-cut apples, as well as inhibiting PPO and POD activities and increasing APX activity. All above findings established a reliable basis for the inhibitory mechanism of paeonol against tyrosinase and therefore contributed to its application in anti-browning.

Impact of Sodium Silicate Supplemented, IR-Treated Panax Ginseng on Extraction Optimization for Enhanced Anti-Tyrosinase and Antioxidant Activity: A Response Surface Methodology (RSM) Approach

Ginseng has long been widely used for its therapeutic potential. In our current study, we investigated the impact of abiotic stress induced by infrared (IR) radiations and sodium silicate on the upregulation of antioxidant and anti-tyrosinase levels, as well as the total phenolic and total flavonoid contents of the Korean ginseng (Panax ginseng C.A. Meyer) variety Yeonpoong. The RSM-based design was used to optimize ultrasonic-assisted extraction time (1-3 h) and temperature (40-60 °C) for better anti-tyrosinase activity and improved antioxidant potential. The optimal extraction results were obtained with a one-hour extraction time, at a temperature of 40 °C, and with a 1.0 mM sodium silicate treatment. We recorded maximum anti-tyrosinase (53.69%) and antioxidant (40.39%) activities when RSM conditions were kept at 875.2 mg GAE/100 g TPC, and 3219.58 mg catechin/100 g. When 1.0 mM sodium silicate was added to the media and extracted at 40 °C for 1 h, the highest total ginsenoside content (368.09 mg/g) was recorded, with variations in individual ginsenosides. Ginsenosides Rb1, Rd, and F2 were significantly affected by extraction temperature, while Rb2 and Rc were influenced by the sodium silicate concentration. Moreover, ginsenoside F2 increased with the sodium silicate treatment, while the Rg3-S content decreased. Interestingly, higher temperatures favored greater ginsenoside diversity while sodium silicate impacted PPD-type ginsenosides. It was observed that the actual experimental values closely matched the predicted values, and this agreement was statistically significant at a 95% confidence level. Our findings suggest that the application of IR irradiation in hydroponic systems can help to improve the quality of ginseng sprouts when supplemented with sodium silicate in hydroponic media. Optimized extraction conditions using ultrasonication can be helpful in improving antioxidant and anti-tyrosinase activity.

Analysis of Three Species of Cassipourea Traditionally Used for Hypermelanosis in Selected Provinces in South Africa

There is a growing demand and use of herbal cosmetics for skin purposes due to their perceived safety when applied to the skin. Three Cassipourea species commonly known as "ummemezi" are used interchangeably by women in rural areas of Eastern Cape and KwaZulu-Natal provinces to treat hypermelanosis as well as sun protection. We conducted a phytochemical comparison of three Cassipourea species; Cassipourea flanaganii (Schinz) Alston, Cassipourea gummiflua Tul. verticillata (N.E.Br.) J. Lewis and Cassipourea malosana (Baker) Alston by Liquid Chromatography-Mass Spectrometry (LC-MS/MS) analysis in negative mode. The results obtained from the LC-MS/MS yielded a total number of twenty-four compounds of different chemical classes, including fatty acids, steroids, di- and tri-terpenoids, flavonoids, phenolic acids, and eighteen among them were tentatively identified. The LC-MS /MS analysis showed that the three studied Cassipourea extracts contain compounds that have anti-tyrosinase activity and consequently. The presence of these compounds, either in synergy or individually, can be attributed to the anti-tyrosinase effect. Although the traditional names of the species are used interchangeably, they are different, however, they possess similar skin-lightening properties. Despite the recent popularity of modern cosmetic products, plants continue to play an important role in the local cosmetics industry in South Africa's Eastern Cape and KwaZulu-Natal community provinces.

The efficacy of natural bioactive compounds against prostate cancer: Molecular targets and synergistic activities

Globally, prostate cancer (PCa) is regarded as a challenging health issue, and the number of PCa patients continues to rise despite the availability of effective treatments in recent decades. The current therapy with chemotherapeutic drugs has been largely ineffective due to multidrug resistance and the conventional treatment has restricted drug accessibility to malignant tissues, necessitating a higher dosage resulting in increased cytotoxicity. Plant-derived bioactive compounds have recently attracted a great deal of attention in the field of PCa treatment due to their potent effects on several molecular targets and synergistic effects with anti-PCa drugs. This review emphasizes the molecular mechanism of phytochemicals on PCa cells, the synergistic effects of compound-drug interactions, and stem cell targeting for PCa treatment. Some potential compounds, such as curcumin, phenethyl-isothiocyanate, fisetin, baicalein, berberine, lutein, and many others, exert an anti-PCa effect via inhibiting proliferation, metastasis, cell cycle progression, and normal apoptosis pathways. In addition, multiple studies have demonstrated that the isolated natural compounds: d-limonene, paeonol, lanreotide, artesunate, and bicalutamide have potential synergistic effects. Further, a significant number of natural compounds effectively target PCa stem cells. However, further high-quality studies are needed to firmly establish the clinical efficacy of these phytochemicals against PCa.

Dietary flavonoid myricetin 3-O-galactoside suppresses α-melanocyte stimulating hormone-induced melanogenesis in B16F10 melanoma cells by regulating PKA and ERK1/2 activation

Melanogenesis is the process where skin pigment melanin is produced through tyrosinase activity. Overproduction of melanin causes skin disorders such as freckles, spots, and hyperpigmentation. Myricetin 3-O-galactoside (M3G) is a dietary flavonoid with reported bioactivities. M3G was isolated from Limonium tetragonum and its anti-melanogenic properties were investigated in α-melanocyte stimulating hormone-stimulated B16F10 melanoma cells. The in vitro anti-melanogenic capacity of M3G was confirmed by inhibited tyrosinase and melanin production. M3G-mediated suppression of melanogenic proteins, tyrosinase, microphthalmia-associated transcription factor (MITF), and tyrosinase-related proteins (TRP)-1 and TRP-2, were confirmed by mRNA and protein levels, analyzed by RT-qPCR and Western blot, respectively. Furthermore, M3G suppressed Wnt signaling through the inhibition of PKA phosphorylation. M3G also suppressed the consequent phosphorylation of CREB and nuclear levels of MITF. Analysis of MAPK activation further revealed that M3G increased the activation of ERK1/2 while p38 and JNK activation remained unaffected. Results showed that M3G suppressed melanogenesis in B16F10 cells by decreasing tyrosinase production and therefore inhibiting melanin formation. A possible action mechanism was the suppression of CREB activation and upregulation of ERK phosphorylation which might cause the decreased nuclear levels of MITF. In conclusion, M3G was suggested to be a potential nutraceutical with anti-melanogenic properties.

Antioxidant activity, anti-tyrosinase activity, molecular docking studies, and molecular dynamic simulation of active compounds found in nipa palm vinegar

Tyrosinase is a key enzyme in melanogenesis and its inhibitors have become increasingly because of their potential activity as hypopigmenting agents which have less side effects. Nipa palm vinegar is an aqueous product that is normally used as a food supplement. The aim of this study was to study the determination of antioxidant activity and tyrosinase inhibitory activities of aqueous extract of original nipa palm vinegar (AE O-NPV), nipa palm vinegar powder (NPV-P) and aqueous extract of nipa palm vinegar powder (AE NPV-P) were examined. Nipa palm vinegars were evaluated the phenolic and flavonoid content, and the active compounds which were submitted to molecular docking and molecular dynamic simulation, chemoinformatics, rule of five, skin absorption and toxicity. The highest phenolic and flavonoid contents in the AE O-NPV were 2.36 ± 0.23 mg gallic acid equivalents/g extract and 5.11 ± 0.59 mg quercetin equivalents/g, and the highest ABTS radical cation scavenging activity was also found. The AE O-NPV, NPV-P and AE NPV-P showed anti-mushroom tyrosinase activity. The HPLC analysis showed that there were vanillic acid and three flavonoids (catechin, rutin and quercetin). The molecular docking study revealed that the binding of the vanillic acid and three flavonoids occurred in the active site residues (histidine and other amino acids). Moreover, the number of hydrogen bond acceptors/donors, solubility, polar surface area and bioavailability score of the vanillic acid and three flavonoids were acceptable compared to Lipinski's Rule of Five. The molecular dynamic simulation showed that vanillic acid interacts with HIS284 through π-π stacking hydrophobic interactions and forms a metal-acceptor interaction with the copper molecule at the tyrosinase active site. All compounds revealed good skin permeability and nontoxicity. Nipa palm vinegar could be a promising source of a new ingredient for tyrosinase inhibition for cosmetics or pharmaceutical products.

Natural tyrosinase enzyme inhibitors: A path from melanin to melanoma and its reported pharmacological activities

The skin containing melanin pigment acts as a protective barrier and counteracts the UVR and other environmental stressors to maintain or restore disrupted cutaneous homeostasis. The production of melanin pigment is dependent on tyrosine levels. L-tyrosine and L-dihydroxyphenylalanine (L-DOPA) can serve both as a substrates and intermediates of melanin synthetic pathway and as inducers and positive regulators of melanogenesis. The biosynthesis of melanin is stimulated upon exposure to UVR, which can also stimulate local production of hormonal factors, which can stimulate melanoma development by altering the chemical properties of eu- and pheomelanin. The process of melanogenesis can be altered by several pathways. One involves activation of POMC, with the production of POMC peptides including MSH and ACTH, which increase intracellular cAMP levels, which activates the MITF, and helps to stimulate tyrosinase (TYR) expression and activity. Defects in OCA1 to 4 affects melanogenic activity via posttranslational modifications resulting in proteasomal degradation and reducing pigmentation. Further, altering, the MITF factor, helps to regulate the expression of MRGE in melanoma, and helps to increase the TYR glycosylation in ER. CRH stimulates POMC peptides that regulate melanogenesis and also by itself can stimulate melanogenesis. The POMC, P53, ACTH, MSH, MC1R, MITF, and 6-BH4 are found to be important regulators for pigmentation. Melanogenesis can affect melanoma behaviour and inhibit immune responses. Therefore, we reviewed natural products that would alter melanin production. Our special focus was on targeting melanin synthesis and TYR enzyme activity to inhibit melanogenesis as an adjuvant therapy of melanotic melanoma. Furthermore, this review also outlines the current updated pharmacological studies targeting the TYR enzyme from natural sources and its consequential effects on melanin production.

Applications of Probiotic Constituents in Cosmetics

Over the past few decades, research on the benefits of beneficial microorganisms on skin health has expanded and attracted a lot of attention. Today, a wide range of probiotic products are becoming available. With their extensive component profiles and varied physiological effects, probiotics, as well as extracts of them, have a significant impact on cosmetics. However, the present boom in consumer interest in alternatives has broadened the probiotic industry's research and development frontiers. Considering the foregoing, it should come as no surprise that probiotics are highly valued for their proven anti-aging, skin whitening, anti-inflammatory, and photoprotective effects. This review aims to compile information on probiotics' properties, their extracts, and preparations used in cosmetics. It also further summarizes research and applications on probiotic fermentation to promote the use of probiotic fermentation products in cosmetics. Notably, this review also adds information on particular properties and mechanisms of action of probiotics, which fills a gap in the research and application of probiotics in skin treatment and care. Their antioxidant and anti-aging qualities have received particular consideration. This review provides a new basis for the broad application of probiotics in cosmetics.

Antioxidant and Enzyme Inhibitory Activities of Rhoifolin Flavonoid: In Vitro and in Silico Studies

Rhoifolin (apigenin-7-O-β-neohesperidoside) belongs to the class of flavonoids and was reported to exhibit anti-inflammatory, cytotoxic, antidiabetic, hepatoprotective, and cardioprotective activities. The current study presents the in-vitro evaluation of the antioxidative effects of rhoifolin by many assays, namely DPPH, CUPRAC, ABTS, phosphomolybdenum, and FRAP. Enzyme inhibitory potential was also evaluated for acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, amylase, and glucosidase enzymes. While results revealed weak antioxidant activities for rhoifolin, the compound demonstrated some promising enzyme inhibitory effects against BChE (4.03 mg GALAE/g) and tyrosinase (7.44 mg KAE/g) but was not active on AChE. Regarding anti-diabetic enzymes, the compound was active on amylase but did not show any inhibition effect on glucosidase. In-silico molecular docking study was performed for rhoifolin on the active site of NADPH oxidase, BChE, and amylase enzymes to verify the observed enzyme inhibitory effect. Good binding affinities were observed for rhoifolin on all the docked enzymes, revealing numerous hydrogen bonds, carbon-hydrogen, van der Waals interactions. This is the first study to evaluate the enzyme inhibition potential of rhoifolin. We concluded that the increase in the degree of glycosylation might decrease the antioxidant abilities of flavonoids and that rhoifolin had moderate enzyme inhibition abilities to be investigated in future studies.

Quercetin Alleviates Lipopolysaccharide-Induced Cell Oxidative Stress and Inflammatory Responses via Regulation of the TLR4-NF-κB Signaling Pathway in Bovine Rumen Epithelial Cells

Subacute rumen acidosis (SARA) will cause an increase in endotoxin, which will have a negative effect on the bovine rumen epithelial cells (BREC). Flavonoids are effective in treating inflammation caused by endotoxin. Quercetin is a vital flavonoid widely occurring in fruits and vegetables and has received significant interest as a prospective anti-inflammatory antioxidant. Nonetheless, quercetin's protective machinery against such damage to BREC induced by lipopolysaccharide (LPS) remains unclear. A combined quercetin and LPS-induced BREC inflammation model was utilized to elucidate the effect of quercetin protecting BREC from LPS-induced injury. After treating BREC with different doses of LPS (1, 5, and 10 μg/mL) for 6 h or 24 h, the mRNA expression of inflammatory factors was detected. Our experimental results show the establishment of the BREC inflammation model via mRNA high expression of pro-inflammatory cytokines in BREC following 6 h treatment with 1 µg/mL LPS. The promotive effect of 80 μg/mL quercetin on BREC growth via the cell counting kit-8 (CCK8) assay was observed. The expression of pro-inflammatory cytokines and chemokines, notably tumor necrosis factor α (TNF-α), Interleukin 1β (IL-1β), IL-6, CC-motif chemokine ligand 2 (CCL2), CCL20, CCL28, and CXC motif chemokine 9 (CXCL9), etc., was significantly reduced by quercetin supplementation. We also analyzed the mRNA detection of related pathways by qRT-PCR. Our validation studies demonstrated that quercetin markedly curbed the mRNA expression of the toll-like receptor 4 (TLR4) and myeloid differentiation primary response protein (MyD88) and the nuclear factor-κB (NF-κB) in LPS-treated BREC. In addition, western blot result outcomes confirmed, as expected, that LPS significantly activated phosphorylation of p44/42 extracellular regulated protein kinases (ERK1/2) and NF-κB. Unexpectedly, this effect was reversed by adding quercetin. To complement western blot results, we assessed p-ERK1/2 and p-p65 protein expression using immunofluorescence, which gave consistent results. Therefore, quercetin's capacity to bar the TLR4-mediated NF-κB and MAPK signaling pathways may be the cause of its anti-inflammatory effects on LPS-induced inflammatory reactions in BREC. According to these results, quercetin may be utilized as an anti-inflammatory medication to alleviate inflammation brought on by high-grain feed, and it also lays out a conceptual foundation regarding the development and utilization of quercetin in the later stage.

Antioxidant and antiaging activities of Cinnamomum burmannii, Michelia champaca and their combinations

Aging is a natural skin process that occurs due to intrinsic and extrinsic factors, such as excessive exposure to ultraviolet light (photoaging). The mechanism of damage involves the production of excess free radicals that trigger oxidative stress in the skin. Determining the natural products that have high antioxidant activities as antiaging is important. Cinnamomum burmannii and Michelia champaca are typical Aceh plants that are believed to have high antioxidant effects. The aim of this study was to determining the contents of C. burmannii and M. champaca as well as to determine the antioxidant and antiaging activities of either individually or combinations. The qualitative phytochemical and semi-quantitative analysis of the extracts were measured using gas chromatography-mass spectroscopy (GC-MS). The antioxidant activity was examined by radical scavenging using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical method while the antiaging activity was measured using the tyrosinase enzyme inhibition test. The phenolic and flavonoid contents of C. burmannii were higher than M. champaca (66.34 vs 24.71 mg gallic acid equivalent/gr and 80.52 vs 60.20 mg quercetin equivalent/gr, respectively. The inhibitory concentration (IC50) of M. champaca extract in inhibiting DPPH indicated that M. champaca had a better antioxidant activity than C. burmannii. The combination of C. burmannii and M. champaca extracts had a lower IC50 compared to M. champaca alone. C. burmannii and M. champaca extracts had a weak potential to inhibit tyrosinase activity (IC50 value ≥1000 μg/mL). In conclusion, this study indicates that M. champaca and C. burmannii have strong antioxidant activities and these might associate with polyphenol contents.

Chemical characterization of the polyphenolic rich fraction of Thunbergia erecta and its therapeutic potential against doxorubicin and cyclophosphamide-induced cognitive impairment in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Thunbergia erecta (Benth.) was traditionally used as anxiolytic, sedative and antidepressant.

AIM OF THE STUDY

The study aimed to characterize T. erecta leaf ethyl acetate fraction of alcohol extract (TEAF) and evaluate its neuroprotective effect on doxorubicin and cyclophosphamide-induced chemobrain.

MATERIALS AND METHODS

Chemical profiling of TEAF was done using (Liquid chromatography coupled with mass (LC-ESI-MS/MS). In vivo chemobrain model was performed by cognitive impairment induced by doxorubicin and cyclophosphamide. Behavioral assessments included moris water maze, y maze, novel object recognition task and passive avoidance tests. Histological examination and oxidative stress markers were investigated. Protein expression of HMDGB1/RAGE/pNF-κB pathway markers was done using western blotting. All results were applied to hippocampus and prefrontal cortex of rats. Molecular docking was done within the active sites of Human Receptor for Advanced Glycation Endproducts (RAGE) using Discovery studio software.

RESULTS

Twenty-one phytoconstituents, mostly polyphenolics, were characterized in TEAF of which eleven compounds were tentatively identified for the first time from T. erecta leaves where rosmarinic acid (11) represents the most prevailing compound. TEAF resulted in a marked dose-dependent amelioration of the histopathological changes evidenced by normal histological structure demonstrated in the hypocampal gesture of rats. TEAF demonstrated an enhanced memory and learning functioning in the different behavioral tests assessed especially at 200 mg/kg. It showed significant long-term spatial memory enhancement manifested by 50.32% increase in probe trial relative to chemobrain-induced group. It showed pronounced antioxidant activity evidenced by the significant elevation of prefrontal cortical and hippocampal reduced glutathione levels by 2.45 and 2.65 folds, respectively relative to the chemobrain-induced group. The pronounced reduction in hydrogen peroxide (1.24-1.93 folds) and malondialdehyde levels (1.42-2.60 folds) with significant elevation of catalase activity (12.65-31.47%) induced by TEAF supported its potent antioxidant activity. TEAF reversed the inflammatory cytokines release induced by chemotherapy via its interference with HMGB1/RAGE pathway suppressing the expression of HMBG1, RAGE, p65 (NF-kB), and IL-1β. In silico studies showed that rosmarinic acid displayed the best fitting at the active site of RAGE (ΔG = -40.39 kcal/mol).

CONCLUSIONS

Thunbergia erecta can act as a promising remedy for chemobrain that further consolidates its traditional importance.

Leveraging the 3-Chloro-4-fluorophenyl Motif to Identify Inhibitors of Tyrosinase from Agaricus bisporus

Tyrosinase (EC 1.14.18.1) is implicated in melanin production in various organisms. There is a growing body of evidence suggesting that the overproduction of melanin might be related to several skin pigmentation disorders as well as neurodegenerative processes in Parkinson's disease. Based on this consideration, the development of tyrosinase inhibitors represents a new challenge to identify new agents in pharmaceutical and cosmetic applications. With the goal of identifying tyrosinase inhibitors from a synthetic source, we employed a cheap and facile preliminary assay using tyrosinase from Agaricus bisporus (AbTYR). We have previously demonstrated that the 4-fluorobenzyl moiety might be effective in interactions with the catalytic site of AbTYR; moreover, the additional chlorine atom exerted beneficial effects in enhancing inhibitory activity. Therefore, we planned the synthesis of new small compounds in which we incorporated the 3-chloro-4-fluorophenyl fragment into distinct chemotypes that revealed the ability to establish profitable contact with the AbTYR catalytic site. Our results confirmed that the presence of this fragment is an important structural feature to improve the AbTYR inhibition in these new chemotypes as well. Furthermore, docking analysis supported the best activity of the selected studied compounds, possessing higher potency when compared with reference compounds.

Understanding the Chemical Composition and Biological Activities of Different Extracts of Secamone afzelii Leaves: A Potential Source of Bioactive Compounds for the Food Industry

Secamone afzelii (Roem. & Schult.) K. Schum (family Asclepiadaceae) is a creeping woody climber used to treat ailments in many traditional medicine systems. The present study aims to examine the antioxidant and enzyme inhibition activities of S. afzelii leaf using different compositions of methanol-water mixture as an extraction solvent. The extracts were characterized by HPLC-ESI-MSⁿ in terms of chemical compounds. The in silico results show that compound 23 (quercitrin) has the higher docking scores among the selected substances and the MD simulation revealed that the interactions with the enzymatic pocket are stable over the simulation time and strongly involve the tyrosinase catalytic Cu atoms. All together the results showed that both 80% and 100% methanolic extracts contained significantly (p < 0.05) the highest total phenolics content while the highest content of total flavonoids was significantly (p < 0.05) extracted by 100% methanol. About 26 compounds were tentatively identified by HPLC-ESI-MSⁿ and 6 of them were quantified using standards. Results showed that the extracts were rich in flavonoids with a relatively high abundance of two kaempferol glycosides comprising 60% of quantified compounds. The 100% and 80% methanol extracts recorded significantly (p < 0.05) the highest total antioxidant, DPPH and ABTS activity as well as tyrosinase and ⍺-amylase inhibitory activities. The best significant (p < 0.05) cholinesterase inhibitory activity and reducing capacity of Fe⁺⁺⁺ and Cu⁺⁺ was recorded from the 80% methanolic extract while 100% ethanolic extract gave the highest significant (p < 0.05) butyrylcholinesterase inhibitory activity. The best glucosidase activity was observed in the 50% and 80% methanolic extracts. Although the water extract displayed the least total phenolics and flavonoids content and consequently the lowest antioxidant and enzyme inhibition activity, it displayed significantly (p < 0.05) the highest chelating power. In conclusion, these results demonstrated the richness of S. afzelii leaf as a potential source of bioactive compounds for the food industry, for the preparation of food supplements and functional foods.

Oxidation of baicalein by tyrosinase and by o-quinones

Baicalein (5,6,7-trihydroxyflavone) has been previously described as an inhibitor of tyrosinase (Guo et al. Int. J. Biol. Macromol. 118 (2018) 57-68). However, long before this article was published this flavonoid had been shown to be a substrate of this enzyme and a catecholic cofactor partially abolishing the lag-phase during oxidation of l-tyrosine. Other compounds with a 1,2,3-triphenol moiety, such as pyrogallol, gallic acid and its esters are also oxidized by tyrosinase. Gallic acid was also shown to reduce tyrosinase-generated o-quinones. We have demonstrated that baicalein is also rapidly oxidized by o-quinones generated from catechols by tyrosinase or by treatment with sodium periodate. Smaller changes of absorbance at 475 nm during oxidation of l-dopa by tyrosinase in the presence of baicalein do not result from enzyme inhibition but from reduction of dopaquinone by baicalein. This reaction prevents formation of dopachrome giving an effect of inhibition, which is only apparent. The actual reaction rates did not decrease but increased in the presence of baicalein, which we demonstrated by measurements of oxygen consumption.

Essential Oil Compounds of Andaliman (Zanthoxylum acanthopodium DC.) Fruit Varieties and Their Utilization as Skin Anti-Aging Using Molecular Docking

Exposure to UV/infrared (IR) radiation is the main extrinsic factor that changes skin morphology and affects the increase in reactive oxygen species (ROS) in skin aging. Ten varieties of andaliman (Zanthoxylum acanthopodium DC.) fruit are presumed to have skin anti-aging compounds via an enzyme-inhibition mechanism. This study aims to compare ten essential oils (EOs) of andaliman fruit varieties, group them according to their varieties, and obtain the chemical components that can be used as potential skin anti-aging agents using molecular docking. EOs were isolated by hydrodistillation, and the determination of the chemical compounds was performed using gas chromatography-mass spectrometry (GC-MS). Using the Orange data mining software, a heatmap was used for grouping and showing the abundance of the compounds of ten varieties. Finally, molecular docking was conducted using the software AutoDockTools 1.5.7. There were 97 chemical components in the ten EOs of andaliman fruit varieties, with the main chemical components being geranyl acetate (29.87%) and D-limonene (26.49%), and they were grouped into three clusters. The chemical components that are prospective candidates as skin anti-aging agents are geranyl acetate and D-limonene, found in abundance in the Sihalus variety of andaliman fruit. These can be developed for applications in the pharmaceutical industry.

Pharmacological activities and effective substances of the component-based Chinese medicine of Ginkgo biloba leaves based on serum pharmacochemistry, metabonomics and network pharmacology

As a potential drug candidate for the treatment of hypertension and complications, it is speculated that the component-based Chinese medicine of Ginkgo biloba leaves (GBCCM) which mainly composed of flavonoid aglycones (FAs) and terpene lactones (TLs) may have different pharmacological effects at different doses or ratios. Taking the normal mice as the study object, metabonomics was conducted by giving different doses of GBCCM. Based on the components of GBCCM absorbed into the blood, the network pharmacological prediction was carried out. By integrating the results of metabonomics and network pharmacology, predict the possible pharmacological effects of GBCCM and conduct experimental verification. It was found that eight of the 19 compounds in GBCCM could be absorbed into the blood. GBCCM mainly affected the signal pathways of unsaturated fatty acid, pyruvate, bile acid, melanin and stem cells. It was speculated that GBCCM might have activities such as lowering blood pressure, regulating stem cell proliferation and melanogenesis. By establishing the models of mushroom tyrosinase, rat bone marrow mesenchymal stem cells (BMSCs) and spontaneously hypertensive rats (SHRs), we found that FAs and TLs showed synergistic effect in hypertension and tyrosinase models, and the optimal ratio was 3:2 (4.4 mg/kg) and 1:1 (0.4 mg/ml), respectively. As effective substances, FAs significantly promoted the proliferation of rat BMSCs on the third and fifth days at the concentration of 0.2 μg/ml (p &lt; 0.05). GBCCM showed a variety of pharmacological effects at different doses and ratios, which provided an important reference for the druggability of GBCCM.

Coumarin-Based Compounds as Inhibitors of Tyrosinase/Tyrosine Hydroxylase: Synthesis, Kinetic Studies, and In Silico Approaches

Cancer represents the main cause of morbidity and mortality worldwide, constituting a serious health problem. In this context, melanoma represents the most aggressive and fatal type of skin cancer, with death rates increasing every year. Scientific efforts have been addressed to the development of inhibitors targeting the tyrosinase enzyme as potential anti-melanoma agents due to the importance of this enzyme in melanogenesis biosynthesis. Coumarin-based compounds have shown potential activity as anti-melanoma agents and tyrosinase inhibitors. In this study, coumarin-based derivatives were designed, synthesized, and experimentally evaluated upon tyrosinase. Compound FN-19, a coumarin-thiosemicarbazone analog, exhibited potent anti-tyrosinase activity, with an IC50 value of 42.16 ± 5.16 µM, being more active than ascorbic acid and kojic acid, both reference inhibitors. The kinetic study showed that FN-19 acts as a mixed inhibitor. Still, for this compound, molecular dynamics (MD) simulations were performed to determine the stability of the complex with tyrosinase, generating RMSD, RMSF, and interaction plots. Additionally, docking studies were performed to elucidate the binding pose at the tyrosinase, suggesting that the hydroxyl group of coumarin derivative performs coordinate bonds (bidentate) with the copper(II) ions at distances ranging from 2.09 to 2.61 Å. Then, MM/PBSA calculations revealed that van der Waals interactions are the most relevant intermolecular forces for complex stabilization. Furthermore, it was observed that FN-19 has a binding energy (ΔEMM) value similar to tropolone, a tyrosinase inhibitor. Therefore, the data obtained in this study will be useful for designing and developing novel coumarin-based analogs targeting the tyrosinase enzyme.

Recent advances in the discovery, biosynthesis, and therapeutic potential of isocoumarins derived from fungi: a comprehensive update

Microorganisms still remain the main hotspots in the global drug discovery avenue. In particular, fungi are highly prolific producers of vast structurally diverse specialized secondary metabolites, which have displayed a myriad of biomedical potentials. Intriguingly, isocoumarins is one distinctive class of fungal natural products polyketides, which demonstrated numerous remarkable biological and pharmacological activities. This review article provides a comprehensive state-of-the-art over the period 2000-2022 about the discovery, isolation, classifications, and therapeutic potentials of isocoumarins exclusively reported from fungi. Indeed, a comprehensive list of 351 structurally diverse isocoumarins were documented and classified according to their fungal sources [16 order/28 family/55 genera] where they have been originally discovered along with their reported pharmacological activities wherever applicable. Also, recent insights around their proposed and experimentally proven biosynthetic pathways are also briefly discussed.

Protective effect of acrocarpus fraxinifolius extract against hepatic fibrosis induced by Gamma irradiation and carbon tetrachloride in albino rats

PURPOSE

Liver fibrosis is considered as one of the ultimate outcomes of chronic liver disorders, characterized by outrageous cell proliferation and abnormal deposition of extracellular matrix, resulting in sever pathological distortions in the architecture and performance of liver tissues. The present study aimed to investigate the protective properties of aqueous methanol extract of Acrocarpus fraxinifolius leaves (AFL) against liver fibrosis induced by dual toxicity of γ-irradiation and carbon tetrachloride (CCl₄) in rats.

METHODS

The animals were exposed to 2 Gy irradiation once/week concurrently with intraperitoneal administration of CCl₄ (0.2 mL/100 g body weight) for seven weeks. Afterwards, liver toxicity and fibrosis were assessed biochemically at cellular and molecular as well as histopathological levels.

RESULTS

The livers of intoxicated rats showed distinct structural and functional changes, compared with the normal rats. The administration of AFL (500 mg/kg, p.o) significantly ameliorated the histopathological manifestations of fibrotic liver evidenced by mitigated steatosis progression, necrosis, fibrotic septa, apoptotic bodies, and immunochistochemical studies of alpha-smooth muscle actin. Also, AFL increased the final body weight, total protein, albumin levels and albumin/globulin ratio. While, the absolute liver weight, liver enzymes, total cholesterol and triglycerides were reduced. A significant modulation was observed in hydroxyproline, transforming growth factor-β and collagen-1expression. Furthermore, AFL exerted a direct effect on liver fibrosis by promoting extracellular matrix degradation via overexpression of the tissue inhibitor metalloproteinase-1, coupled with decease of metalloproteinase-9 activity.

CONCLUSIONS

Our findings suggested that AFL effectively improved the architecture of fibrotic liver and modified the biochemical markers of liver fibrosis.

Morus alba L. root decreases melanin synthesis via sphingosine-1-phosphate signaling in B16F10 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Morus alba L. has long been used for beauty in many Asian countries and regions, including anti-aging and hyperpigmentation.

AIM OF THE STUDY

This study aimed at the inhibitory effect of Morus alba L. root on melanogenesis in B16F10 melanoma cells and the mechanism involved.

MATERIALS AND METHODS

This study evaluated the anti-melanogenic effect of Morus alba L. root extract (MAR) on B16F10 melanoma cells by assessing cell viability, melanin accumulation, cellular tyrosinase activity, intra/inter-cellular S1P levels, cellular S1P-related metabolic enzyme activity, and western blot analysis. In addition, the potential S1P lyase (S1PL) inhibitory constituents in MAR were identified by LC-MS/MS.

RESULTS

Without affecting the viability of B16F10 melanoma cells, MAR inhibited intracellular tyrosinase activity in a dose-dependent manner, thereby reducing the accumulation of melanin. MAR also downregulated the expression level of MITF via activating the ERK signaling pathway. Furthermore, MAR increased the intra/inter-cellular S1P by inhibiting S1PL. Several compounds with inhibitory S1PL activity have been identified in MAR, such as mulberroside A and oxyresveratrol.

CONCLUSIONS

The anti-melanogenic effects of MAR mainly involve promoting MITF degradation mediated via S1P-S1PR3-ERK signaling through increasing cellular S1P levels by inhibiting S1PL activity.

Pinostrobin Suppresses the α-Melanocyte-Stimulating Hormone-Induced Melanogenic Signaling Pathway

Pinostrobin is a dietary flavonoid found in several plants that possesses pharmacological properties, such as anti-cancer, anti-virus, antioxidant, anti-ulcer, and anti-aromatase effects. However, it is unclear if pinostrobin exerts anti-melanogenic properties and, if so, what the underlying molecular mechanisms comprise. Therefore, we, in this study, investigated whether pinostrobin inhibits melanin biosynthesis in vitro and in vivo, as well as the potential associated mechanism. Pinostrobin reduced mushroom tyrosinase activity in vitro in a concentration-dependent manner, with an IC₅₀ of 700 μM. Molecular docking simulations further revealed that pinostrobin forms a hydrogen bond, as well as other non-covalent interactions, between the C-type lectin-like fold and polyphenol oxidase chain, rather than the previously known copper-containing catalytic center. Additionally, pinostrobin significantly decreased α-melanocyte-stimulating hormone (α-MSH)-induced extracellular and intracellular melanin production, as well as tyrosinase activity, in B16F10 melanoma cells. More specifically, pinostrobin inhibited the α-MSH-induced melanin biosynthesis signaling pathway by suppressing the cAMP-CREB-MITF axis. In fact, pinostrobin also attenuated pigmentation in α-MSH-stimulated zebrafish larvae without causing cardiotoxicity. The findings suggest that pinostrobin effectively inhibits melanogenesis in vitro and in vivo via regulation of the cAMP-CREB-MITF axis.

Investigation of phenyllactic acid as a potent tyrosinase inhibitor produced by probiotics

Melanogenesis is responsible for skin pigmentation and the enzymatic browning of foods. Tyrosinases play a major role in melanin synthesis, and many attempts have been made to identify new natural tyrosinase inhibitors, but few have sought to do in microbes. Postbiotics are bioactive compounds produced by the metabolism of probiotics and have been reported to be safe and effective. In this study, we evaluated the tyrosinase inhibitory effects of culture supernatants of probiotics and discovered novel bacterial metabolites that can be used as a potent tyrosinase inhibitor based on metabolomics. Cultures of Bifidobacterium bifidum IDCC 4201 and Lactiplantibacillus plantarum IDCC 3501 showed effective anti-tyrosinase, reduced melanin synthesis, and altered protein expression associated with the melanogenesis pathway. Comparative metabolomics analyses conducted by GC-MS identified metabolites commonly produced by B. bifidum and L. plantarum. Of eight selected metabolites, phenyllactic acid exhibited significant tyrosinase-inhibitory activity. Our findings suggest that applications of probiotic culture supernatants containing high amounts of phenyllactic acid have potential use as anti-melanogenesis agents in food and medicines.

Differential Metabolomic Fingerprinting of the Crude Extracts of Three Asteraceae Species with Assessment of Their In Vitro Antioxidant and Enzyme-Inhibitory Activities Supported by In Silico Investigations

The Asteraceae is a large family, rich in ornamental, economical, and medicinally valuable plants. The current study involves the analytical and pharmacological assessment of the methanolic extracts of three less investigated Asteraceae plants, namely Echinops ritro, Centaurea deflexa, and Tripleurospermum decipiens, obtained by three different extraction methodologies viz. maceration (MAC), ultrasound-assisted extraction (UAE), and homogenizer-assisted extraction (HAE). LC-MS-MS analysis of E. ritro, C. deflexa, and T. decipiens extracts led to the identification of ca. 29, 20, and 33 metabolites, respectively, belonging to flavonoids, phenolic acids, and fatty acids/amides. Although there were significant differences in the quantitative metabolite profiles in the extracts of E. ritro and T. decipiens based on the used extraction method, no significant variation was observed in the extracts of C. deflexa in the three implemented extraction techniques. The antioxidant activities of the nine extracts were assessed in vitro using six different assays viz. DPPH, ABTS, CUPRAC, FRAP, PDA, and metal chelation assay (MCA). The HAE/UAE extracts of E. ritro and the UAE/ MAC extracts of C. deflexa displayed the highest antioxidant activity in the DPPH assay, while the UAE extract of T. decipiens showed the strongest antioxidant activity in both the CUPRAC and MCA assays. The enzyme inhibitory activities of the nine extracts were studied in vitro on five different enzymes viz. tyrosinase, α-amylase, α-glucosidase, acetylcholinesterase (AChE), and butyrylcholinestrase (BChE), affecting various pathological diseases. Concerning C. deflexa, its MAC /UAE extracts showed the strongest inhibition on α-amylase, while its UAE/HAE extracts displayed strong inhibitory power on AChE. However, no significant difference was observed on their effects on tyrosinase or BChE. For T. decipiens, its UAE/HAE showed potent inhibition to α-glucosidase, MAC/ HAE significantly inhibited AChE and BChE, while UAE could strongly inhibit tyrosinase enzyme. For E. ritro, all extracts equally inhibited α-amylase and α-glucosidase, MAC/HAE strongly affected tyrosinase, HAE/MAC best inhibited BChE, while HAE inhibited AChE to a greater extent. Chemometric analysis using PCA plot was able to discriminate between the plant samples and between the implemented extraction modes. The in vitro enzyme inhibitory activities of the extracts were supported by in silico data, where metabolites, such as the lignan arctiin and the flavonoid vicenin-2, dominating the extract of C. deflexa, displayed strong binding to AChE. Similarly, chlorogenic and dicaffeoyl quinic acids, which are some of the major metabolites in the extracts of E. ritro and T. decipiens, bound with high affinity to α-glucosidase.

Tyrosinase Inhibition Activity and Phytochemical Screening of Melaleuca leucadendron L. Leaves

Melaleuca leucadendron L. is a plant whose almost all parts (bark, leaves, twigs, and fruit) can be used as medicine, such as antioxidants, antifungals, sedative effects, and anti-hyaluronidase. This research was conducted to determine tyrosinase inhibition activity and compound content of M. leucadendron leaves. Maceration of M. leucadendron leaves was done in methanol, then carried out liquid-liquid fractionation with n-butanol, chloroform, and water. Methanol extract, butanol fraction, chloroform fraction, and water fraction were tested for phytochemical screening and tyrosinase inhibition using L-DOPA substrate with an ELISA plate well reader. The results of the tyrosinase inhibition activity test at concentrations of 100, 1000 and 10000 μg/mL respectively showed that methanol extract 29.532%, 55.227%, 89.583%; butanol fraction 29.313%, 59.174%, 94.737%, chloroform fraction 21.820%, 24.671%; 53.765%; water fraction 24,086%, 47.661%, 91.118%. Inhibition of the tyrosinase enzyme is shown through the IC50 value from methanol extract, butanol fraction and water fraction, and kojic acid as a positive control, respectively 645.438 μg/mL, 517.935 μg/mL, 669.403 μg/mL, 50.064 μg/mL. Phytochemical screening showed that the extract and fraction contained tannins, flavonoids, saponins, terpenes, and steroids. These results indicate that the butanol fraction is more potent as an anti-tyrosinase agent than the others.

Genus Lupinus (Fabaceae): a review of ethnobotanical, phytochemical and biological studies

OBJECTIVES

Lupinus is a large and diverse genus comprising approximately 200 species, belonging to the family Fabaceae. Lupinus plants have been used for heart stimulants, nerves, urinary tract infections, skin disorders, and psoriasis in folk medicine. This review aims to recap the traditional medicinal uses, nutritional value, phytochemical profile, and biological activities of Lupinus species.

KEY FINDINGS

From the literature survey, Lupinus is considered as a factory of various phytochemicals like flavonoids, iso-flavonoids, alkaloids, triterpenoids. The presence of proteins, essential fatty acids, and amino acids, as well as alkaloids, minerals, and dietary fibers, indicated that the plants in this genus had a high nutritional value. The Lupinus extracts displayed promising antidiabetic, anticancer, antimicrobial, antidiabetic, antihypertensive, antioxidant, anti-inflammatory, and antimicrobial activities.

CONCLUSIONS

The current review provides updated information that could drive the researchers for further studies. The in vitro and in vivo experiments have demonstrated various pharmacological properties. Some pharmacokinetic and toxicological investigations are warranted to ensure its safety and validity for human use.

Mechanisms of ultraviolet-induced melasma formation: A review

Melasma, a pigmentation disorder, commonly occurs in exposed skin areas and can be attributed to several factors. Ultraviolet radiation (UVR) is the primary factor that induces and aggravates melasma. Considering gene expression, exposed skin areas experience abnormal gene expression, involving melanin metabolism, oxidative stress, impaired skin barrier function, and abnormal composition of nerve factors. From a histological perspective, UVR can cause basement membrane collapse, melanocyte sinking, and disorders of skin lipid metabolism. Emerging therapies have focused on these pathological alterations in melasma, including platelet-rich plasma, mesotherapy, and phytochemicals. Understanding the role of UVR in the development of melasma can facilitate early prevention and highlight the future direction of melasma treatment.

Rifampicin is not an inhibitor of tyrosinase

Rifampicin has been previously described as an inhibitor of tyrosinase (Chai et al., Int. J. Biol. Macromol. 102 (2017) 425-430). However, rifampicin contains a p-diphenol group and compounds with such a moiety have been shown before to reduce tyrosinase-generated o-quinones. Rifampicin also shows strong absorption in a region completely overlapping with the visible absorption band of dopachrome, the oxidation product of L-tyrosine and L-dopa, whose concentration is measured spectrophotometrically in the standard enzymatic assay to monitor the activity of tyrosinase. We have demonstrated that rifampicin is also rapidly oxidized by o-quinones generated from catechols by tyrosinase or by treatment with sodium periodate. Smaller changes of absorbance at 475 nm during oxidation of L-dopa by tyrosinase in the presence of rifampicin do not result from enzyme inhibition but from oxidation of rifampicin by dopaquinone, which leads to rapid decrease of rifampicin absorption in this range. The actual reaction rates are not affected, which we have demonstrated by measurements of oxygen consumption. Rifampicin behaves therefore as other compounds with reducing properties, such as ascorbic acid, hydroquinone, hydrazine derivatives, and flavonoids, some of which have also been incorrectly described before as inhibitors of tyrosinase.

Anethole rich Clausena heptaphylla (Roxb.) Wight & Arn., essential oil pharmacology and genotoxic efficiencies

Anethole, a widely used industrial flavoring agent is majorly sourced from anise and star anise. The present study is aimed to the in-depth pharmacological analysis i.e. anti-diabetic, skin whitening, neurodegenerative disorder inhibitory activities of anethole-rich Clausena heptaphylla leaf essential oil (ARCHEO) (88.59%) as revealed by the Gas Chromatography/Mass Spectrometry (GC/MS) analysis and further confirmed by proton nuclear magnetic resonance ¹H-NMR as well as to compare with standard compound anethole. ARCHEO (ABTS EC₅₀ 6.97 ± 0.004 µg/mL; Protease assay 4.51 ± 0.004 µg/mL) outperformed the standard compound anethole (ABTS EC₅₀ 9.48 ± 0.048 µg/mL; Protease assay EC₅₀ 22.64 ± 0.016 µg/mL) in antioxidant and anti-inflammatory experiments. ARCHEO was also shown to be more effective than the reference compound anethole in terms of anti-diabetic activity (EC₅₀ 22.35 ± 0.121 µg/mL), tyrosinase inhibitory activity (EC₅₀ 16.45 ± 0.012 µg/mL), and anti-cholinesterase activity (EC₅₀ 22.32 ± 0.016 µg/mL). However, ARCHEO exhibited lower antimicrobial activity towards all the tested microbes compared to standard compound anethole and as for the MIC, ARCHEO was effective only towards Salmonella typhimurium (60 µg/mL), Streptococcus mutans (20 µg/mL), and Aspergillus fumigatus (75 µg/mL). ARCHEO (11.11%) and anethole (12.33%) showed no genotoxic effect based on Allium cepa assay mitotic index value. Thus, ARCHEO could be a commercially viable and widely available cheaper source of anethole, which has buoyant demand in the field of food flavoring, fragrance, and pharmaceutical industries.

A New Xanthone Glycoside from Mangifera indica L.: Physicochemical Properties and In Vitro Anti-Skin Aging Activities

A new xanthone glycoside, 1,3,5,6-tetrahydroxyxanthone-C-4-β-d-glucopyranoside was isolated from the methanol extract of Mangifera indica leaves (Anacardiaceae) growing in Egypt. The structure was clarified by 1D and 2D-NMR spectroscopic data. The physicochemical properties of the compound such as lipophilicity, solubility, and formulation considerations were predicted via in silico ADMET technique using the SwissADME server. This technique provided Lipinski’s rule of five, such as GIT absorption, distribution, metabolism, and skin permeation. The in vitro inhibitory activities against aging-mediated enzymes such as collagenase, elastase, hyaluronidase, and tyrosinase were assessed. The compound exhibited remarkable anti-collagenase, anti-elastase, anti-hyaluronidase, and anti-tyrosinase effects with IC₅₀ values of 1.06, 419.10, 1.65, and 0.48 µg/mL, respectively, compared to the positive control. The compound showed promising predicted aqueous solubility and reasonable skin penetration suggesting the suitability of the compound for topical formulation as an anti-aging agent for cosmetic preparations.

Microbial Transformation and Biological Activities of the Prenylated Aromatic Compounds from Broussonetia kazinoki

Broussonetia kazinoki has been used as a traditional medicine for the treatment of burns and acne, and its extracts have been found to show tyrosinase inhibitory and anticancer activities. In this study, the tyrosinase inhibitory and cytotoxic activities of B. kazinoki were explored, leading to the isolation of kazinol C (1), kazinol E (2), kazinol F (3), broussonol N (4), and kazinol X (5), of which the compounds 4 and 5 have not been previously reported. Microbial transformation has been recognized as an efficient tool to generate more active metabolites. Microbial transformation of the major compounds 1 and 3 was conducted with Mucor hiemalis, where four glucosylated metabolites (6-9) were produced from 1, while one hydroxylated (10) and one glucosylated (11) metabolites were obtained from 3. Structures of the isolated metabolites were determined by extensive spectroscopic analyses. All compounds were evaluated for their tyrosinase inhibitory and cytotoxic activities. Compound 3 and its metabolites, kazinol Y (10) and kazinol F-4″-O-β-d-glucopyranoside (11), exhibited the most potent tyrosinase inhibitory activities with the IC₅₀ values ranging from 0.71 to 3.36 µM. Meanwhile, none of the metabolites, except for kazinol C-2',3″-di-O-β-d-glucopyranoside (7), showed moderate cytotoxic activities (IC₅₀ 17.80 to 24.22 µM) against A375P, B16F10 and B16F1 cell lines.