Tyrosinase Inhibitory Activity Research Articles

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Active Constituents with Tyrosinase Inhibitory Activities from Waste Tobacco Leaves.

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

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

This study investigated protein hydrolysates obtained from Lentinus squarrosulus and Lentinus edodes fruiting bodies via gastric protease hydrolysis and ultrafiltration, yielding peptides with a molecular weight below 6.5kDa. These hydrolysates displayed significant tyrosinase inhibitory activity similar to positive controls, peptide from Chinese quince seed (RHAKF) and kojic acid. L. squarrosulus-derived hydrolysates exhibited superior antioxidant properties compared to L. edodes in DPPH (47% vs. 23%) and ABTS (77% vs. 23%) assays. Identified bioactive peptides, particularly LILGGSSS from L. squarrosulus, interacted with tyrosinase through hydrogen bonds at specific residues. Notably, these protein hydrolysates showcased potent tyrosinase inhibition without cytotoxic effects, presenting promising prospects for addressing hyperpigmentation caused by excessive tyrosinase activity from stress or UV exposure.

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

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

Biochemical and In Silico Studies on Triazole Derivatives as Tyrosinase Inhibitors: Potential Treatment of Hyperpigmentation Related Skin Disorders.

Tyrosinase is a versatile, glycosylated copper-containing oxidase enzyme that mainly catalyzes the biosynthesis of melanin in mammals. Its overexpression leads to the formation of excess melanin, resulting in hyperpigmentary skin disorders, such as dark spots, melasma, freckles, etc. Therefore, inhibition of tyrosinase is a therapeutic approach for the treatment of hyperpigmentation. The current study focused on evaluating tyrosinase inhibitory activities of triazole derivatives 1-20, bearing different substituents on the phenyl ring. 17 derivatives have shown a potent tyrosinase inhibition with IC50 values between 1.6 to 13 μM, as compared to the standard drug, i.e., kojic acid (IC50 = 24.1 ± 0.5 μM). Particularly, compounds 11 and 15 displayed 12 times more potent inhibitory effects than the kojic acid. The structure-activity relationship revealed that substituting halogens at the C-4 position of the benzene ring renders remarkable anti-tyrosinase activities. Compounds 1-3 and 8 showed a competitive type of inhibition, while compounds 5, 11, and 15 showed a non-competitive mode of inhibition. Next, we performed molecular docking analyses to study the binding modes and interactions between the ligands (inhibitors) and the active site of the tyrosinase enzyme (receptor). Besides this, we have assessed the toxicity profile of inhibitors on the BJ human fibroblast cell line. The majority of the newly identified tyrosinase inhibitors were found to be noncytotoxic. The results presented herein form the basis of further studies on triazole derivatives as potential drug leads against tyrosinase-related diseases.

The Antityrosinase Activity of Mitragyna speciosa Korth Leaf Ethanolic Extract

The kratom plant (Mitragyna speciosa Korth) is a the plant that is traditionally used to soften the skin. Kratom leaves have very strong antioxidant activity so they are predicted also to have anti-tyrosinase activity. The potential inhibition of tyrosinase enzyme activity is thought to come from the content of flavonoid compounds, polyphenols, steroids, tannins, and quinones. This research aims to determine the tyrosinase inhibitory activity of ethanol extract of M. speciosa leaves. The inhibitory activity of the tyrosinase enzyme using L-DOPA as substrate and kojic acid as positive control. Antityrosinase testing was carried out by in vitro method using UV-vis spectrophotometer through determination of IC50 value. The results of the antityrosinase activity test of ethanol extract of M. speciosa leaves showed an IC50 value of 2117.708 ppm. The ethanol extract of M. speciosa leaves is scientifically proven to have antityrosinase activity with a weak category.

In Vitro Evaluation of Purple Sweet Potato Leaf Extract (Ipomoea batatas) as a Tyrosinase Inhibitor and Malondialdehyde Formation Inhibitor

The study purple sweet potato is known to contain flavonoids, a class of natural polyphenols with the capability to mitigate skin pigmentation. The research aims to assess the antioxidant and tyrosinase inhibitory activities of purple sweet potato extracts obtained through hexane, ethyl acetate, ethanol, and water solvents. The results of phytochemical identification show that the extract contains various secondary metabolites which have the potential to act as antioxidants. The DPPH method IC50 values of 6948.12ppm for n-hexane, 3015.19ppm for ethyl acetate, 128.05ppm for ethanol, and 791.77ppm for water extract. The MDA inhibitor test IC50 values of 2067.02ppm for n-hexane, 1968.13ppm for ethyl acetate, 116.14ppm for ethanol, and 921.14ppm for water extract. In the tyrosinase inhibitor assay, IC50 values were 1328.29ppm for n-hexane, 1245.13ppm for ethyl acetate, 217.35ppm for ethanol, and 391.21ppm for water extract. Tuckey test statistics, ethanol extract was not significantly different from the positive control in the DPPH test, MDA inhibitor and tyrosinase test. These findings suggest that purple sweet potato extracts, particularly the ethanol extract, hold promise as natural ingredients with antioxidant and tyrosinase inhibitory properties, making them potential candidates for safe and effective skin brightening formulations.

Melatonin/Sericin Wound Healing Patches: Implications for Melanoma Therapy.

Melatonin and sericin exhibit antioxidant properties and may be useful in topical wound healing patches by maintaining redox balance, cell integrity, and regulating the inflammatory response. In human skin, melatonin suppresses damage caused by ultraviolet radiation (UVR) which involves numerous mechanisms associated with reactive oxygen species/reactive nitrogen species (ROS/RNS) generation and enhancing apoptosis. Sericin is a protein mainly composed of glycine, serine, aspartic acid, and threonine amino acids removed from the silkworm cocoon (particularly Bombyx mori and other species). It is of interest because of its biodegradability, anti-oxidative, and anti-bacterial properties. Sericin inhibits tyrosinase activity and promotes cell proliferation that can be supportive and useful in melanoma treatment. In recent years, wound healing patches containing sericin and melatonin individually have attracted significant attention by the scientific community. In this review, we summarize the state of innovation of such patches during 2021-2023. To date, melatonin/sericin-polymer patches for application in post-operational wound healing treatment has been only sparingly investigated and it is an imperative to consider these materials as a promising approach targeting for skin tissue engineering or regenerative dermatology.

Anti-Melanogenic Effects of Takifugu flavidus Muscle Hydrolysate in B16F10 Melanoma Cells and Zebrafish.

Abnormal melanogenesis can lead to hyperpigmentation. Tyrosinase (TYR), a key rate-limiting enzyme in melanin production, is an important therapeutic target for these disorders. We investigated the TYR inhibitory activity of hydrolysates extracted from the muscle tissue of Takifugu flavidus (TFMH). We used computer-aided virtual screening to identify a novel peptide that potently inhibited melanin synthesis, simulated its binding mode to TYR, and evaluated functional efficacy in vitro and in vivo. TFMH inhibited the diphenolase activities of mTYR, reducing TYR substrate binding activity and effectively inhibiting melanin synthesis. TFMH indirectly reduced cAMP response element-binding protein phosphorylation in vitro by downregulating melanocortin 1 receptor expression, thereby inhibiting expression of the microphthalmia-associated transcription factor, further decreasing TYR, tyrosinase related protein 1, and dopachrome tautomerase expression and ultimately impeding melanin synthesis. In zebrafish, TFMH significantly reduced black spot formation. TFMH (200 μg/mL) decreased zebrafish TYR activity by 43% and melanin content by 52%. Molecular dynamics simulations over 100 ns revealed that the FGFRSP (T-6) peptide stably binds mushroom TYR via hydrogen bonds and ionic interactions. T-6 (400 μmol/L) reduced melanin content in B16F10 melanoma cells by 71% and TYR activity by 79%. In zebrafish, T-6 (200 μmol/L) inhibited melanin production by 64%. TFMH and T-6 exhibit good potential for the development of natural skin-whitening cosmetic products.

Antioxidant, Tyrosinase Inhibition Activity, and In Vitro SPF Evaluation of Pepino Fruit Extract (Solanum muricatum Aiton) in Different Solvent Types and Concentrations

Solvent is a key factor that affects the effectiveness of active compound extraction from plant materials (simplisia). This study aimed to determine the optimal type and concentration of solvent used in the extraction of pepino fruit based on the parameter of antioxidant and tyrosinase inhibition activity, as well as Sun Protection Factor (SPF) value. The extraction was carried out using the maceration method with ethanol or ethyl acetate as the solvent, each at concentrations of 50%, 70%, and 96%, respectively. The antioxidant activity of the extracts was evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. The inhibition of tyrosinase and the determination of the SPF value were carried out using in vitro test. The results showed that the ethyl acetate extract was better than that of the ethanol extract in terms of antioxidant activity, tyrosinase inhibition, and SPF value. In the ethyl acetate solvent, a concentration of 96% provided the strongest antioxidant, tyrosinase inhibition activity, and the second highest in SPF test. It can be concluded that the optimal solvent for extracting pepino fruit as promising compound for sunscreen formulation is 96% ethyl acetate.

The Effect of α-Arbutin on UVB-Induced Damage and Its Underlying Mechanism.

Ultraviolet radiation can heighten tyrosinase activity, stimulate melanocyte production, impede the metabolism of numerous melanocytes, and result in the accumulation of plaques on the skin surface. α-Arbutin, a bioactive substance extracted from the arbutin plant, has been widely used for skin whitening. In this study, the whitening effect of α-arbutin by inhibiting tyrosinase activity and alleviating the photoaging effect induced by UVB are investigated. The results indicate that α-arbutin can inhibit skin inflammation, and its effectiveness is positively correlated with concentration. Moreover, α-arbutin can reduce the skin epidermal thickness, decrease the number of inflammatory cells, and down-regulate the expression levels of IL-1β, IL-6 and TNF-α, which are inflammatory factors. It also promotes the expression of COL-1 collagen, thus playing an important role in anti-inflammatory action. Network pharmacology, metabolomics and transcriptomics further confirm that α-arbutin is related to the L-tyrosine metabolic pathway and may interfere with various signaling pathways related to melanin and other photoaging by regulating metabolic changes. Therefore, α-arbutin has a potential inhibitory effect on UVB-induced photoaging and possesses a whitening effect as a cosmetic compound.

Isolation, purification, and biological activities of polysaccharides from Amorpha fruticosa flowers

The extraction, isolation, structural characterisation and biological activities of polysaccharides from Amorpha fruticosa flowers were investigated. First, the crude polysaccharide AFP was extracted, and two major purified polysaccharide fractions AFP-2 and AFP-3 were isolated. The molecular weight and monosaccharide compositions of AFP-2 and AFP-3 were determined. Then the antioxidant activities of AFP, AFP-2 and AFP-3 were assessed by DPPH radical, β-Carotene bleaching and hydroxyl radical assays. All three tested polysaccharides showed good antioxidant activity while AFP was the strongest one. The study also showed that AFP, AFP-2 and AFP-3 have good tyrosinase inhibition, moisture absorption and retention activities. The results will provide a helpful reference for the application of polysaccharide from Amorpha fruticosa flowers as a natural cosmetic ingredient.

Tyrosinase and Peroxiredoxin Inhibitory Action of Ethanolic Extracts of Memecylon malabaricum Leaves

The study aimed to determine the tyrosinase and peroxiredoxin inhibitory action of ethanolic extracts of Memecylon malabaricum leaves. The phytoconstituents present in Memecylon malabaricum were analysed for their inhibitory activity against the tyrosinase and peroxiredoxin enzymes by molecular docking, and their molecular interactions were confirmed. The Qikprop module checked their pharmacokinetic profiles. The ethanolic extracts were prepared, and they were analysed for antityrosinase and antioxidant activity by in vitro methods. All the fourteen phytoconstituents obtained from Memecylon malabaricum were docked with two proteins, tyrosinase (5I38) and peroxiredoxin (1HD2), and MM1 was the well-interacted compound. The ethanolic extract was evaluated for tyrosinase inhibitory activity and antioxidant activity using the DPPH radical scavenging method and was compared with the standard ascorbic acid. It was concluded that the ethanolic extract of Memecylon malabaricum was active, and further pharmacological studies were needed to confirm their potency.

Classification of buckwheat honey produced in Kazakhstan according to their biochemical ingredients and bioactivities by chemometric approach

Herein, nineteen buckwheat honey samples collected from 19 stations of different ecological zones of Kazakhstan were analysed for their pollen density, physicochemical properties, chemical composition, antioxidant, anticholinesterase, tyrosinase inhibitory, and urease inhibitory activities with chemometric approaches. Twelve phenolic compounds and fumaric acid were identified using HPLC-DAD, and mainly fumaric, p-hydroxybenzoic, p-coumaric, trans-2-hydroxy cinnamic acids, and chrysin were detected in all samples. The honey samples collected from the Northern zone exhibited best antioxidant activity in lipid peroxidation inhibitory (IC50:8.65 ± 0.50 mg/mL), DPPH• (IC50:17.07 ± 1.49 mg/mL), ABTS•+ (IC50:8.90 ± 0.65 mg/mL), CUPRAC (A0.50:7.51 ± 0.30 mg/mL) and metal chelating assay (IC50:10.39 ± 0.71 mg/mL). In contrast, South-eastern zone samples indicated better acetylcholinesterase (55.57 ± 0.83%), butyrylcholinesterase (49.59 ± 1.09%), tyrosinase (44.40 ± 1.21%), and moderate urease (24.57 ± 0.33%) inhibitory activities at 20 mg/mL. The chemometric classification of nineteen buckwheat honey was performed using PCA and HCA techniques. Both were supported by correlation analysis. Thirteen compounds contributed significantly to the clustering of buckwheat honey based on geographical origin.