A comprehensive review of the therapeutic potential of α-arbutin

Determination of arbutin in vitro and in vivo by LC-MS/MS: Pre-clinical evaluation of natural product arbutin for its early medicinal properties

ETHNOPHARMACOLOGICAL RELEVANCE

Arbutin is a naturally occurring glucoside extracted from plants, known for its antioxidant and tyrosinase inhibiting properties. It is widely used in cosmetic and pharmaceutical industries. With in-depth study of arbutin, its application in disease treatment is expanding, presenting promising development prospects. However, reports on the metabolic stability, plasma protein binding rate, and pharmacokinetic properties of arbutin are scarce.

AIM OF THE STUDY

The aim of this study is to enrich the data of metabolic stability and pharmacokinetics of arbutin through the early pre-clinical evaluation, thereby providing some experimental basis for advancing arbutin into clinical research.

MATERIALS AND METHODS

We developed an efficient and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for determining arbutin in plasma. We investigated the metabolic and pharmacokinetic properties of arbutin through in vitro metabolism assay, cytochrome enzymes P450 (CYP450) inhibition studies, plasma protein binding rate analysis, Caco-2 cell permeability tests, and rat pharmacokinetics to understand its in vivo performance.

RESULTS

In vitro studies show that arbutin is stable, albeit with some species differences. It exhibits low plasma protein binding (35.35 ± 11.03% ∼ 40.25 ± 2.47%), low lipophilicity, low permeability, short half-life (0.42 ± 0.30 h) and high oral bioavailability (65 ± 11.6%). Arbutin is primarily found in the liver and kidneys and is eliminated in the urine. It does not significantly inhibit CYP450 up to 10 μM, suggesting a low potential for drug interactions. Futhermore, preliminary toxicological experiments indicate arbutin's safety, supporting its potential as a therapeutic agent.

CONCLUSION

This study provides a comprehensive analysis the drug metabolism and pharmacokinetics (DMPK) of arbutin, enriching our understanding of its metabolism stability and pharmacokinetics properties, It establishes a foundation for further structural optimization, pharmacological studies, and the clinical development of arbutin.

De novo biosynthesis of β-arbutin in Corynebacterium glutamicum via pathway engineering and process optimization

BACKGROUND

β-Arbutin, a hydroquinone glucoside found in pears, bearberry leaves, and various plants, exhibits antioxidant, anti-inflammatory, antimicrobial, and anticancer effects. β-Arbutin has wide applications in the pharmaceutical and cosmetic industries. However, the limited availability of high-performance strains limits the biobased production of β-arbutin.

RESULTS

This study established the β-arbutin biosynthetic pathway in C. glutamicum ATCC13032 by introducing codon-optimized ubiC, MNX1, and AS. Additionally, the production titer of β-arbutin was increased by further inactivation of csm and trpE to impede the competitive metabolic pathway. Further modification of the upstream metabolic pathway and supplementation of UDP-glucose resulted in the final engineered strain, C. glutamicum AR11, which achieved a β-arbutin production titer of 7.94 g/L in the optimized fermentation medium.

CONCLUSIONS

This study represents the first successful instance of de novo β-arbutin production in C. glutamicum, offering a chassis cell for β-arbutin biosynthesis.

Nutrient-delivery and metabolism reactivation therapy for melanoma

To fulfil the demands of rapid proliferation, tumour cells undergo significant metabolic alterations. Suppression of hyperactivated metabolism has been proven to counteract tumour growth. However, whether the reactivation of downregulated metabolic pathways has therapeutic effects remains unexplored. Here we report a nutrient-based metabolic reactivation strategy for effective melanoma treatment. L-Tyrosine-oleylamine nanomicelles (MTyr-OANPs) were constructed for targeted supplementation of tyrosine to reactivate melanogenesis in melanoma cells. We found that reactivation of melanogenesis using MTyr-OANPs significantly impeded the proliferation of melanoma cells, primarily through the inhibition of glycolysis. Furthermore, leveraging melanin as a natural photothermal reagent for photothermal therapy, we demonstrated the complete eradication of tumours in B16F10 melanoma-bearing mice through treatment with MTyr-OANPs and photothermal therapy. Our strategy for metabolism activation-based tumour treatment suggests specific nutrients as potent activators of metabolic pathways.

Arbutin intervention ameliorates memory impairment in a rat model of lysolecethin induced demyelination: Neuroprotective and anti-inflammatory effects

Cognitive impairment (CI) and memory deficit are prevalent manifestations of multiple sclerosis (MS). This study explores the therapeutic potential of arbutin on memory deficits using a rat hippocampal demyelination model induced by lysophosphatidylcholine (LPC). Demyelination was induced by bilateral injection of 1% LPC into the CA1 area of the hippocampus, and the treated group received daily arbutin injections (50 mg/kg, i.p) for two weeks. Arbutin significantly improved memory impairment 14 days post-demyelination as assessed by Morris water maze test. Histological and immunohistochemical analyses demonstrated that arbutin reduced demyelination suppressed pro-inflammatory markers (IL-1β, TNF-α) and increased anti-inflammatory cytokine IL-10. Arbutin also diminished astrocyte activation, decreased iNOS, enhanced anti-oxidative factors (Nrf2, HO-1), and exhibited neuroprotective effects by elevating myelin markers (MBP) and brain derived neurotrophic factor (BDNF). These findings propose arbutin as a potential therapeutic candidate for multiple sclerosis-associated memory deficits, warranting further clinical exploration.

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.

Preparation and efficacy verification of three-dimensional printed partitioned multi-effect precision-care gel facial mask

OBJECTIVE

A partition multi-effect precision-care gel facial mask conforming to facial skin characteristics was prepared using three-dimensional (3D) printing technology.

METHODS

First, the hydrogel matrix and humectant of a 3D-printed gel for facial masks were screened, and three 3D-printed gels of arbutin, hexapeptide, and salicylic acid were prepared with whitening, wrinkle removal, and oil control functions, respectively. Skin irritation tests were performed on the gels. Physicochemical properties such as pH, heat and cold tolerance were evaluated. The efficacy of three 3D-printed gels was assessed by measuring melanin value, wrinkle depression score, and oil secretion. Finally, the facial mask model design and printing parameters were studied, and a partition multi-effect precision-care gel facial mask was printed in line with facial skin characteristics.

RESULTS

For the 3D-printed facial mask, the gel prescription with 2% hydroxyethyl cellulose gel as matrix and 7% glycerol as humectant was the best. The prepared 3D-printed gel did not irritate the human skin, and its physicochemical properties met the Chinese facial mask industry standard (QB/T2872-2017). We showed that three types of 3D-printed gels containing arbutin, hexapeptide, and salicylic acid could be applied to the corresponding parts of the face to solve different problems, such as facial skin dullness, wrinkles, and oil secretion. Therefore, according to facial physiological characteristics, the facial mask model was designed for the forehead and nasolabial fold, which needs to be anti-wrinkled; the cheek, which needs to be whitened; and the nose and chin, which need oil control. The optimal printing parameters were 0.26 mm nozzle diameter, 90 mm/s printing speed, 30% filling density, 140% wire extrusion ratio, and 0.25 mm layer height. Different skin care effects can be achieved using a three-nozzle printer to print arbutin, hexapeptide, or salicylic acid gel on the mask's forehead and nasolabial fold, cheek, and nose and chin, respectively.

CONCLUSION

The 3D-printed partition multi-effect care gel facial mask prepared according to the skin features of different parts of the face can overcome the problem of the single skincare effect of the mass-produced facial masks.

Theoretical framework to evaluate antioxidant synergistic effects from the coextraction of marjoram, rosemary and parsley

Synergies between compounds in food ingredients have been commonly obtained by the mixing of extracts produced individually. A different approach, based on the coextraction of plants and a new theoretical framework to identify synergistic and antagonistic effects in the coextracts, has been proposed in this study for the first time. The Pressurized Liquid Extraction (PLE) of rosemary and marjoram with parsley at several plant ratios was carried out and the antioxidant activity (ABTS and cellular assays) and phenolic compounds of the extracts were evaluated. Synergistic effects on the antioxidant activity of the extracts were identified from all the plant combinations. The HPLC-PAD analysis of the samples did not show a relation between the concentration of the main phenolic compounds in the coextracts and the observed antioxidant synergistic effects. The proposed theoretical framework may be successfully used for the determination of synergies in the bioactivity of extracts obtained by coextraction.

Selection of a Digitalis purpurea Cell Line with Improved Bioconversion Capacity of Hydroquinone into Arbutin

This study aimed to investigate the biotransformation capabilities of a hydroquinone-tolerant Digitalis purpurea cell line (DpHQ) for bioconverting hydroquinone (HQ) into arbutin, a compound with significant therapeutic and cosmetic applications. The research evaluated the influence of various HQ concentrations, feeding protocols, and carbon sources on arbutin bioconversion yield. By using HPLC-MS for the quantification of arbutin in biomass and medium, the study revealed that higher precursor (HQ) concentration led to a more pronounced growth inhibition under single dosing than sequential dosing. At lower sugar (3%) and precursor (4 mM HQ) levels, arbutin predominantly remained within the cells, whereas higher sugar (6%) and HQ (5-6 mM) levels promoted its release into the medium. Arbutin production ranged from 591 mg/L under single dosing to 3049 mg/L with sequential dosing, with the highest yield being achieved with 5 mM HQ in divided doses and 6% glucose. This study holds novelty for being the first to demonstrate the DpHQ's tolerance to high concentrations of HQ and its efficient capabilities to bioconvert HQ to arbutin, indicating that D. purpurea is equipped with the enzymes required for this process. These aspects highlight its potential as a biotechnological source for arbutin synthesis.

Hacking the International Nomenclature of Cosmetic Ingredients List- How to Read Ingredients in Cosmetic Products and What Is Important for a Dermatologist to Know?

Skin specialists and practitioners are commonly requested to recommend on cosmetic products to improve skin appearance and address certain "non-medical" concerns. During residency and further education, dermatologists rarely expand their knowledge regarding cosmetic ingredients, except if they are a cause of medical condition or disease, such as contact dermatitis. This review provides guidelines to the INCI list structure, together with basic principles of cosmetic products formulation.

Valorization of biomass polyphenols as potential tyrosinase inhibitors

Tyrosinases (TYRs; EC 1.14.18.1) catalyze two sequential oxidative reactions of the melanin biosynthesis pathway and play an important role in mammalian pigmentation and enzymatic browning of fruit and vegetables. Inhibition of TYR activity is therefore an attractive target for new drugs and/or food ingredients. In addition, increasing evidence suggests that TYR regulation could be a novel target for treatments of cancer and Parkinson's disease. Biomasses, notably industrial byproducts and biowaste, are good sustainable sources of phytochemicals that may be valorized into bioactive compounds including TYR inhibitors. This review presents potential applications of biomass-derived polyphenols targeting TYR inhibition. Insights into structure-activity relationships of several polyphenols and their glycosides are highlighted. Finally, some remarks and perspectives on research into new TYR inhibitors from biomass waste are provided.

Preparation and characterization of brain-targeted polymeric nanocarriers (Frankincense-PMBN-lactoferrin) and in-vivo evaluation on an Alzheimer's disease-like rat model induced by scopolamine

Experiments have demonstrated that frankincense may offer protection against scopolamine-induced Alzheimer's disease by mitigating cholinergic dysfunction and inhibiting inflammatory mediators. Nevertheless, its instability and limited water solubility lead to diminished medicinal efficacy. In this study, we utilized PMBN (poly [MPC-co-(BMA)-co-(MEONP)]) as a nanocarrier for targeted brain drug delivery of frankincense, employing lactoferrin as a ligand for precise targeting. Characterization of nanoparticle properties was conducted through FTIR and FESEM analysis, and the in-vitro drug release percentage from the nanoparticles was quantified. To induce Alzheimer's-like dementia in rats, scopolamine was intraperitoneally administered at a dose of 1 mg/kg/day for 14 days. Subsequently, behavioral assessments (Y-maze, passive avoidance test, tail suspension test) were performed, followed by evaluations of acetylcholinesterase (AChE), reduced glutathione (GSH), catalase (CAT), and brain histopathology at the conclusion of the treatment period. The results revealed that the nanoparticles had a size of 106.6 nm and a zeta potential of -3.8 mV. The maximum release of frankincense in the PBS environment from PMBN nanoparticles was 18.2 %, in accordance with the Peppas model. Behavioral tests indicated that targeted drug nanoparticles (F-PMBN-Lf) exhibited the capability to alleviate stress and depression while enhancing short-term memory in scopolamine-induced animals. Additionally, F-PMBN-Lf counteracted the scopolamine-induced elevation of AChE activity and GSH levels. However, it resulted in decreased activity of the antioxidant enzyme CAT compared to the scopolamine group. Histological analysis of brain tissue suggested that F-PMBN-Lf exerted a notable neuroprotective effect, preserving neuronal cells in contrast to the scopolamine-induced group. It appears that the polymer nanoparticles containing this plant extract have introduced a novel neuroprotective approach for the treatment of Alzheimer's disease.

Synthesis, in silico modelling, and in vitro biological evaluation of substituted pyrazole derivatives as potential anti-skin cancer, anti-tyrosinase, and antioxidant agents

Twenty-five azole compounds (P1-P25) were synthesised using regioselective base-metal catalysed and microwave-assisted approaches, fully characterised by high-resolution mass spectrometry (HRMS), nuclear magnetic resonance (NMR), and infrared spectra (IR) analyses, and evaluated for anticancer, anti-tyrosinase, and anti-oxidant activities in silico and in vitro. P25 exhibited potent anticancer activity against cells of four skin cancer (SC) lines, with selectivity for melanoma (A375, SK-Mel-28) or non-melanoma (A431, SCC-12) SC cells over non-cancerous HaCaT-keratinocytes. Clonogenic, scratch-wound, and immunoblotting assay data were consistent with anti-proliferative results, expression profiling therewith implicating intrinsic and extrinsic apoptosis activation. In a mushroom tyrosinase inhibition assay, P14 was most potent among the compounds (half-maximal inhibitory concentration where 50% of cells are dead, IC50 15.9 μM), with activity greater than arbutin and kojic acid. Also, P6 exhibited noteworthy free radical-scavenging activity. Furthermore, in silico docking and absorption, distribution, metabolism, excretion, and toxicity (ADMET) simulations predicted prominent-phenotypic actives to engage diverse cancer/hyperpigmentation-related targets with relatively high affinities. Altogether, promising early-stage hits were identified - some with multiple activities - warranting further hit-to-lead optimisation chemistry with further biological evaluations, towards identifying new skin-cancer and skin-pigmentation renormalising agents.

Influence of Five Drying Methods on Active Compound Contents and Bioactivities of Fresh Flowers from Syringa pubescens Turcz

The flower of Syringa pubescens Turcz. is used in Chinese folk medicine and also as a flower tea for healthcare. The effects of five drying methods on the active compound contents, the antioxidant abilities, anti-inflammatory properties and enzyme inhibitory activities were evaluated. The plant materials were treated using shade-drying, microwave-drying, sun-drying, infrared-drying and oven-drying. The seven active compounds were simultaneously determined using an HPLC method. Furthermore, the chemical profile was assessed using scanning electron microscopy, ultraviolet spectroscopy and infrared spectroscopy. The antioxidant capacities and protective effects on L02 cells induced with hydrogen peroxide were measured. The anti-inflammatory effects on lipopolysaccharide-induced RAW264.7 cells were investigated. The enzyme inhibitory activities were determined against α-amylase, α-glucosidase cholinesterases and tyrosinase. The results indicated that drying methods had significant influences on the active compound contents and biological properties. Compared with other samples, the OD samples possessed low IC50 values with 0.118 ± 0.004 mg/mL for DPPH radical, 1.538 ± 0.0972 for hydroxyl radical and 0.886 ± 0.199 mg/mL for superoxide radical, while the SHD samples had stronger reducing power compared with other samples. The SHD samples could be effective against H2O2-induced injury on L02 cells by the promoting of T-AOC, GSH-PX, SOD and CAT activities and the reducing of MDA content compared with other samples. Furthermore, SPF samples, especially the SHD sample, could evidently ameliorate inflammation through the inhibition of IL-6, IL-1β and TNF-α expression. All the studied SPF samples exhibited evidently inhibitory effects on the four enzymes. The IC50 values of inhibitory activity on α-glucosidase and α-amylase from SHD sample were 2.516 ± 0.024 and 0.734 ± 0.034 mg/mL, respectively. SD samples had potential inhibitory effects on cholinesterases and tyrosinase with IC50 values of 3.443 ± 0.060 and 1.732 ± 0.058 mg/mL. In consideration of active compound contents and biological activities, it was recommended that SHD and SD be applied for drying SPF at an industrial scale.

Biological and clinical significance of the glypican-3 gene in human lung adenocarcinoma: An in silico analysis

Glypican-3 (GPC3), a membrane-bound heparan sulfate proteoglycan, has long been found to be dysregulated in human lung adenocarcinomas (LUADs). Nevertheless, the function, mutational profile, epigenetic regulation, co-expression profile, and clinicopathological significance of the GPC3 gene in LUAD progression are not well understood. In this study, we analyzed cancer microarray datasets from publicly available databases using bioinformatics tools to elucidate the above parameters. We observed significant downregulation of GPC3 in LUAD tissues compared to their normal counterparts, and this downregulation was associated with shorter overall survival (OS) and relapse-free survival (RFS). Nevertheless, no significant differences in the methylation pattern of GPC3 were observed between LUAD and normal tissues, although lower promoter methylation was observed in male patients. GPC3 expression was also found to correlate significantly with infiltration of B cells, CD8+, CD4+, macrophages, neutrophils, and dendritic cells in LUAD. In addition, a total of 11 missense mutations were identified in LUAD patients, and ~1.4% to 2.2% of LUAD patients had copy number amplifications in GPC3. Seventeen genes, mainly involved in dopamine receptor-mediated signaling pathways, were frequently co-expressed with GPC3. We also found 11 TFs and 7 miRNAs interacting with GPC3 and contributing to disease progression. Finally, we identified 3 potential inhibitors of GPC3 in human LUAD, namely heparitin, gemcitabine and arbutin. In conclusion, GPC3 may play an important role in the development of LUAD and could serve as a promising biomarker in LUAD.

Protective effect of arbutin against cyclophosphamide-induced oxidative stress, inflammation, and hepatotoxicity via Nrf2/HO-1 pathway in rats

Cyclophosphamide (CP) is a potent anticancer drug widely employed in chemotherapy against various types of cancer. However, CP leads to toxicity to non-targeted organs, including the liver and this limits its clinical use. This study explored the role of arbutin (ARB) against CP-mediated oxidative and inflammatory reactions and hepatotoxicity. Rats were administered ARB (25 and 50 mg/kg) for 14 days and CP (150 mg/kg). CP triggered liver tissue injury with marked increase in serum AST, ALT, ALP, and bilirubin, and hepatic malondialdehyde (MDA) and nitric oxide (NO) coupled with diminution of GSH, SOD, catalase, and GPx. Liver NF-kB p65, NOS, IL-6, TNF-α, Bax and caspase-3 were upregulated by CP injection and IL-10 and Bcl-2 were decreased. ARB prevented liver injury, suppressed MDA, NO, NF-kB p65, inflammatory markers, Bax and caspase-3 in CP-treated rats. ARB restored antioxidants, IL-10 and Bcl-2, and enhanced Nrf2 and hemeoxygenase-1 (HO) both gene and protein in the liver of rats. In conclusion, these results pinpointed the protective role of ARB on oxidative and inflammatory reactions, apoptosis, and hepatotoxicity in rats. This hepatoprotective activity was linked to the ability of ARB to modulate Nrf2/HO-1 pathway.

Fabrication of polyvinyl pyrrolidone-K90/Eudragit RL100-based dissolving microneedle patches loaded with alpha-arbutin and resveratrol for skin depigmentation

Alpha-arbutin (AA) and resveratrol (Res) are widely used in skin-lightening products. However, current topical formulations have minimal skin-lightening effects due to the low absorption and poor solubility of these active compounds. This study investigated the efficacy and safety of using dissolving microneedle (DMN) patches to improve the delivery of AA and Res for skin depigmentation. The DMN patches (F0-F3) fabricated from polyvinyl pyrrolidone-K90 (PVP-K90)/Eudragit RL100 blends successfully penetrated excised porcine skin and showed sufficient mechanical strength to resist compression forces. Loading DMNs with 10% AA and 2% Res at a ratio of 5 : 1 (F3) resulted in a synergistic interaction between the drugs with desirable dissolving ability, drug loading, and stability. Furthermore, both in vitro and in vivo studies revealed that the use of F3 DMN patches successfully enhanced the intradermal delivery of AA and Res over a 24 h period, with the delivered amount being higher (∼2.6 times) than that provided by a cream formulation (P < 0.05). After removing the DMN patches, the mice's skin was spontaneously and completely resealed within 12 h. In clinical studies, F3 DMN patches slightly decreased the melanin index of the participants without causing skin irritation or erythema at any time during the 24 h period when the patches were applied (P < 0.05). Moreover, application of the patches for 24 h was not found to affect skin hydration, transepidermal water loss, or skin elasticity. Therefore, AA/Res-loaded DMN patches could offer a promising approach for the effective local delivery of cosmetic agents for skin depigmentation.

Green-Efficient Enzymatic Synthesis and Characterization of Liposoluble 6'/6″-O-Lauryl Phenolic Glycosides with Enhanced Intestinal Permeability

Arbutin, salidroside, polydatin, and phlorizin are typically natural bioactive phenolic glycosides. To improve the liposolubility and bioavailability, highly liposoluble derivatives including 6'-O-lauryl arbutin, 6'-O-lauryl salidroside, 6″-O-lauryl polydatin, and 6″-O-lauryl phlorizin were efficiently synthesized by enzymatic acylation in a green solvent 2-MeTHF. Their reaction conversions reached 84.4, 99.5, 99.8, and 89.1%, respectively, when catalyzed by Lipozyme 435 at 20 mg/mL at 50 °C. As expected, the derivatives had high log P (1.66-2.37) and retained good antioxidant activity, making them potential alternatives to butylated hydroxytoluene (BHT) and tert-butyl-hydroquinone (TBHQ) in lipid systems. Then, the intestinal permeability characteristics and metabolism of phenolic glycosides and their derivatives were investigated based on Caco-2 monolayers. The permeability of polydatin and phlorizin was mainly through active transport, but that of arbutin and salidroside involved both passive diffusion and active uptake. The acylated derivatives suffered from severe CES-mediated hydrolysis but exhibited a larger transported amount than phenolic glycosides.

Evaluating the Application Potential of a Recombinant Ganoderma Protein as Bioactive Ingredients in Cosmetics

The aim of this study was to evaluate the application potential of a recombinant fungal immunomodulatory protein from Ganoderma lucidum (rFIP-glu). First, a recombinant plasmid pPIC9K::FIP-glu-His was transferred into Pichia pastoris for the production of protein. The protein was then to assess its free radical scavenging abilities and the effect on the viability of both human immortalized keratinocytes (HaCaT cells) and mouse B16-F10 melanoma cells (B16 cells) in vitro, followed by the effect on the melanin synthesis of B16 cells. The results of SDS-PAGE and western blot showed that rFIP-glu was successfully expressed. Furtherly, a bioactivity assay in vitro indicated that the scavenging rate of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals reached 84.5% at 6.0 mg/mL (p ≤ 0.0001) of rFIP-glu, showing strong antioxidant activity. Subsequently, a safety evaluation demonstrated that rFIP-glu promoted the proliferation of HaCaT cells, with the cell viability reaching 124.3% at 48 μg/mL (p ≤ 0.01), regarding the cell viability of B16 cells after exposure to rFIP-glu (48 μg/mL) significantly inhibited, to 80.7% (p ≤ 0.01). Besides, rFIP-glu inhibited the melanin synthesis of B16 cells in a dose-dependent manner from 100–1000 μg/mL, and rFIP-glu at 500 μg/mL (p ≤ 0.01) exhibited the highest intracellular melanin amount reduction of 16.8%. Furthermore, a mechanism analysis showed that rFIP-glu inhibited tyrosinase (TYR) activity by up-regulating the expression of the microphthalmia-associated transcription factor (MITF) and down-regulating the gene expression of TYR and tyrosinase-related protein-1 (TYRP-1), thus inhibiting melanin synthesis. The data implied that rFIP-glu had significant antioxidant activity and whitening potency. It should be used as raw materials for cosmeceutical applications.

Unraveling the therapeutic potential of natural products in the prevention and treatment of leukemia

Leukemia is a heterogeneous group of hematological malignancies distinguished by differentiation blockage and uncontrolled proliferation of myeloid or lymphoid progenitor cells in the bone marrow (BM) and peripheral blood (PB). There are various types of leukemia in which intensive chemotherapy regimens or hematopoietic stem cell transplantation (HSCT) are now the most common treatments associated with severe side effects and multi-drug resistance in leukemia cells. Therefore, it is crucial to develop novel therapeutic approaches with adequate therapeutic efficacy and selectively eliminate leukemic cells to improve the consequences of leukemia. Medicinal plants have been utilized for ages to treat multiple disorders due to their diverse bioactive compounds. Plant-derived products have been used as therapeutic medication to prevent and treat many types of cancer. Over the last two decades, 50 % of all anticancer drugs approved worldwide are from natural products and their derivatives. Therefore this study aims to review natural products such as polyphenols, alkaloids, terpenoids, nitrogen-containing, and organosulfur compounds as antileukemic agents. Current investigations have identified natural products efficiently destroy leukemia cells through diverse mechanisms of action by inhibiting proliferation, reactive oxygen species production, inducing cell cycle arrest, and apoptosis in both in vitro, in vivo, and clinical studies. Current investigations have identified natural products as suitable promising chemotherapeutic and chemopreventive agents. It played an essential role in drug development and emerged as a possible source of biologically active metabolites for therapeutic interventions, especially in leukemia. DATA AVAILABILITY: Data will be made available on request.

Combinatorial metabolic engineering enables high yield production of α-arbutin from sucrose by biocatalysis

α-Arbutin has been widely used as a skin-whitening ingredient. Previously, we successfully produced α-arbutin via whole-cell biocatalysis and found that the conversion rate of sucrose to α-arbutin was low (~45%). To overcome this issue, herein, we knocked out the genes of enzymes related to the sucrose hydrolysis, including sacB, sacC, levB, and sacA. The sucrose consumption was reduced by 17.4% in 24 h, and the sucrose conversion rate was increased to 51.5%. Furthermore, we developed an inducible protein degradation system with Lon protease isolated from Mesoplasma florum (MfLon) and proteolytic tag to control the PfkA activity, so that more fructose-6-phosphate (F6P) can be converted into glucose-1-phosphate (Glc1P) for α-arbutin synthesis, which can reduce the addition of sucrose and increase the sucrose conversion efficiency. Finally, the pathway of F6P to Glc1P was enhanced by integrating another copy of glucose 6-phosphate isomerase (Pgi) and phosphoglucomutase (PgcA); a high α-arbutin titer (~120 g/L) was obtained. The sucrose conversion rate was increased to 60.4% (mol/mol). In this study, the substrate utilization rate was boosted due to the attenuation of its hydrolysis and the assistance of the intracellular enzymes that converted the side product back into the substrate for α-arbutin synthesis. This strategy provides a new idea for the whole-cell biocatalytic synthesis of other products using sucrose as substrate, especially valuable glycosides.Key points The genes of sucrose metabolic pathway were knocked out to reduce the sucrose consumption. The by-product fructose was reused to synthesize α-arbutin. The optimized whole-cell system improved sucrose conversion by 15.3%.

Sustained Release Microneedles: Materials and Applications in Facial Rejuvenation

Wrinkled and loose skin resulting from collagen degradation along with fibers decreasing reflects the youth diminishing. Microneedles (MNs) have opened up new avenues for the development of painless and noninvasive transdermal drug delivery systems for facial rejuvenation. Encapsulated drugs or molecules are transmitted to targeted tissues via percutaneous microchannels, which eliminate potential gastric stimulation or first-pass metabolic effects, as well as boost patient compliance. Although MNs are considered effective and feasible therapeutic alternatives to metals, silicon, and polymers, traditional procedures with reduction processes continue to encounter methodological limitations. In recent years, promising additive manufacturing processes such as three-dimensional printing and two-photon polymerization manufacturing have been developed with the aim of overcoming the limitations by traditional processes to facilitate an efficient and economic production mode. This review summarizes the design, material selection, and manufacturing method for recently advanced MN systems. Furthermore, we also highlight specific polymeric or natural microneedle products, like hyaluronan, plant derivates, and vitamins, for esthetic applications in this review. Impact Statement In this review, the materials and manufactural routes of microneedles (MNs) are detailed. Moreover, similar to the diagnostic or therapeutic MNs, the feature of dispensation with training and ready-to-use is perfect for beautification and anti-aging, which necessitate repeated and long-term usage. Furthermore, the specific polymeric or natural products for esthetic applications of MNs are highlighted in this review.

Efficient Whole-Cell Biotransformation for α-Arbutin Production through the Engineering of Sucrose Phosphorylase Combined with Engineered Cell Modification

α-Arbutin is extensively used in cosmetic industries. The lack of highly active enzymes and the cytotoxicity of hydroquinone limit the biosynthesis of α-arbutin. In this study, a whole-cell biocatalytic approach based on enzyme engineering and engineered cell modification was identified as effective in enhancing α-arbutin production. First, a sucrose phosphorylase (SPase) mutant with higher enzyme activity was obtained by experimental screening. Next, to avoid the oxidation of hydroquinone, we established an anaerobic process to improve the robustness of the cells by knocking out lytC, sdpC, and skfA in Bacillus subtilis and overcoming the inhibitory effect of a high concentration of hydroquinone. Finally, the engineered strain was used for biotransformation in a 5 L fermenter with batch feeding for 24 h. The final yield of α-arbutin achieved was 129.6 g/L, which may provide a basis for the large-scale industrial production of α-arbutin.

Copper chelating peptides derived from tilapia (Oreochromis niloticus) skin as tyrosinase inhibitor: Biological evaluation, in silico investigation and in vivo effects

Binuclear copper ions at the active site determine the catalysis of tyrosinase (TYR)¹ whose activity can be inhibited by copper's chelation with other compounds. In this study, tilapia (Oreochromis niloticus) skin was used to generate TYR-inhibitory peptides after being treated by different enzymes and 4 h-Alcaline protease hydrolysate exhibited the highest TYR inhibition and copper chelation. Immobilized metal affinity chromatography was used for purifying copper chelating peptides, among which PFRMY (IC₅₀: 0.43 ± 0.08 mg/mL) and RGFTGM (IC₅₀: 1.61 ± 0.04 mg/mL) exhibited the highest TYR-inhibitory capacity and the lowest docking energy. Both two peptides inhibited TYR in a mixed manner and interacted with key residues binding to copper ions within TYR mainly by hydrogen bonds and hydrophobic forces, while PFRMY had a more compact and stable conjugation with TYR. Zebrafish assay revealed that PFRMY reduced not only melanin synthesis but in vivo TYR activity.

Elucidating the Role of Santalol as a Potent Inhibitor of Tyrosinase: In Vitro and In Silico Approaches

This research work focuses on the potential application of an organic compound, santalol, obtained from santalum album, in the inhibition of the enzyme tyrosinase, which is actively involved in the biosynthesis of melanin pigment. Over-production of melanin causes undesirable pigmentation in humans as well as other organisms and significantly downgrades their aesthetic value. The study is designed to explain the purification of tyrosinase from the mushroom Agaricus bisporus, followed by activity assays and enzyme kinetics to give insight into the santalol-modulated tyrosinase inhibition in a dose-dependent manner. The multi-spectroscopic techniques such as UV-vis, fluorescence, and isothermal calorimetry are employed to deduce the efficiency of santalol as a potential candidate against tyrosinase enzyme activity. Experimental results are further verified by molecular docking. Santalol, derived from the essential oils of santalum album, has been widely used as a remedy for skin disorders and a potion for a fair complexion since ancient times. Based on enzyme kinetics and biophysical characterization, this is the first scientific evidence where santalol inhibits tyrosinase, and santalol may be employed in the agriculture, food, and cosmetic industries to prevent excess melanin formation or browning.

Arbutin-modified microspheres prevent osteoarthritis progression by mobilizing local anti-inflammatory and antioxidant responses

Osteoarthritis (OA) is a common degenerative joint disease worldwide and currently there is no effective strategy to stop its progression. It is known that oxidative stress and inflammation can promote the development of OA, and therapeutic strategies against these conditions may alleviate OA. Arbutin (ARB), a major ingredient of the Chinese medicinal herb cowberry leaf, exerts good antioxidant and anti-inflammatory activities yet has not been studied in OA. Here we developed ARB-loaded gelatine methacryloyl-Liposome (GM-Lipo@ARB) microspheres which showed long-term release of ARB and excellent cartilage-targeting effects. The ARB-loaded microspheres effectively reduced the inflammatory response in interleukin (IL)-1β-treated arthritic chondrocytes. Moreover, the synthesized GM-Lipo@ARB microspheres regulated cartilage extracellular matrix (ECM) homeostasis through anti-inflammation effect via inhibiting NF-κB signaling and anti-oxidative stress effect via activating Nrf2 pathway. Intra-articular use of GM-Lipo@ARB can effectively reduce inflammation and oxidative stress in the articular cartilage and thus, attenuating OA progression in a mouse model. The study proposed a novel ARB-laden functional microsphere, GM-Lipo@ARB, and demonstrated that this compound may be used as an alternative therapeutics for treating OA.

Supercritical Carbon Dioxide Extraction Process for Hibiscus taiwanensis S. Y. Hu and Tyrosinase Inhibitory Activity of Its Extract

In this study, the bioactive components in the stem of Hibiscus taiwanensis S. Y. Hu were extracted by supercritical carbon dioxide (SC-CO2), and the inhibition activity of the extract tyrosinase was analyzed. When the particle size of the powder was controlled to be 50 mesh, the effects of temperatures (40, 45, 50, 55, and 60 °C), pressures (15, 20, 25, 30, and 35 MPa), concentrations of entrainment agent (ethanol) (60, 80, and 95%) and CO2 flow rates (80, 100, 120, and 140 L/min) on the extraction rate, respectively, were studied with the single-variable method. The optimal parameters included an extraction temperature of 55 °C, an extraction pressure of 30 MPa, 80% ethanol as the entrainment agent, and the CO2 flow rate of 100 L/min. Under the optimal conditions, the extraction rate of Hibiscus taiwanensis S. Y. Hu reached more than 0.5% within 2 h. At the same time, the chemical compositions of the extract were investigated by using high-resolution liquid chromatography-mass spectrometry (LC-MS) equipped with a linear ion trap-electrostatic field orbital trap. In addition, the related activity of extract in the stem Hibiscus taiwanensis S. Y. Hu was evaluated by tyrosinase inhibition experiments. The results showed that the inhibition rate of the extract with a concentration of 0.25 mg/mL to tyrosinase reached 35.60%, indicating that the extract by SC-CO2 had the potential to be used for whitening active raw materials.

Advances in Biomedical Functions of Natural Whitening Substances in the Treatment of Skin Pigmentation Diseases

Pigmentation diseases can lead to significant color differences between the affected part and the normal part, resulting in severe psychological and emotional distress among patients. The treatment of pigmentation diseases with good patient compliance is mainly in the form of topical drugs. However, conventional hydroquinone therapy contributes to several pathological conditions, such as erythema, dryness, and skin desquamation, and requires a longer treatment time to show significant results. To address these shortcomings, natural whitening substances represented by kojic acid and arbutin have gradually become the candidate ingredients of traditional local preparations due to their excellent biological safety. This review focuses on several natural whitening substances with potential therapeutic effects in pigmentation disease and their mechanisms, and a thorough discussion has been conducted into the solution methods for the challenges involved in the practical application of natural whitening substances.

Clinical Potential of Himalayan Herb Bergenia ligulata: An Evidence-Based Study

Herbal products have been used in traditional systems of medicine and by ethnic healers for ages to treat various diseases. Currently, it is estimated that about 80% of people worldwide use herbal traditional medicines against various ailments, partly due to easy accessibility and low cost, and the lower side effects they pose. Bergenia ligulata, a herb ranging from the Himalayas to the foothills, including the north-eastern states of India, has traditionally been used as a remedy against various diseases, most prominently kidney stones. The medicinal properties of B. ligulata have been attributed to bergenin, its most potent bioactive component. Apart from bergenin, the other compounds available in B. ligulata are arbutin, gallic acid, protocatechuic acid, chlorogenic acid, syringic acid, catechin, ferulic acid, afzelechin, paashaanolactone, caryophyllene, 1,8-cineole, β-eudesmol, stigmasterol, β-sitosterol, parasorbic acid, 3-methyl-2-buten-1-ol, phytol, terpinen-4-ol, tannic acid, isovalaric acid, avicularin, quercetin, reynoutrin, and sitoinoside I. This review summarizes various medicinal properties of the herb, along with providing deep insight into its bioactive molecules and their potential roles in the amelioration of human ailments. Additionally, the possible mechanism(s) of action of the herb's anti-urolithiatic, antioxidative, antipyretic, anti-diabetic, anti-inflammatory and hepatoprotective properties are discussed. This comprehensive documentation will help researchers to better understand the medicinal uses of the herb. Further studies on B. ligulata can lead to the discovery of new drug(s) and therapeutics for various ailments.

Arbutin improves gut development and serum lipids via Lactobacillus intestinalis

Arbutin has been widely studied in whitening, anti-inflammatory, and antioxidant. However, the interaction between arbutin and intestinal microbes has been rarely studied. Thus, mice were treated with arbutin concentrations of 0, 0.1, 0.2, 0.4, and 1 mg/ml. We found that arbutin promoted gut development such as villus length, villus areas, and villus length/crypt depth (L/D). Total cholesterol (TC), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) were significantly reduced by low concentrations of arbutin. Importantly, we analyzed the microbial composition in the control and 0.4 mg/ml arbutin group and found that the abundance of Lactobacillus intestinalis (L. intestinalis) was highest and enhanced in arbutin. Further, mice were fed with oral antibiotics and antibiotics + 0.4 mg/ml arbutin and then we transplanted fecal microbes from oral 0.4 mg/ml arbutin mice to mice pretreated with antibiotics. Our results showed that arbutin improves gut development, such as villus width, villus length, L/D, and villus areas. In addition, L. intestinalis monocolonization was carried out after a week of oral antibiotics and increased villus length, crypt depth, and villus areas. Finally, in vitro arbutin and L. intestinalis co-culture showed that arbutin promoted the growth and proliferation of L. intestinalis. Taken together, our results suggest that arbutin improves gut development and health of L. intestinalis. Future studies are needed to explore the function and mechanism of L. intestinalis affecting gut development.

Arbutin Protects Retinal Pigment Epithelium Against Oxidative Stress by Modulating SIRT1/FOXO3a/PGC-1α/β Pathway

Age-related macular degeneration (AMD), which is the leading cause of blindness among the elderly in western societies, is majorly accompanied by retinal pigment epithelium (RPE) degeneration. Because of the irreversible RPE cell loss among oxidative stress, it is crucial to search for available drugs for atrophic (dry) AMD. RNA-Seq analysis revealed that genes related to aging and mitochondrial health were differentially expressed under Arbutin treatment, whereas compared to oxidative injury, our study demonstrated that Arbutin substantially abrogated oxidative stress-induced cell senescence and apoptosis linked to intracellular antioxidant enzyme system homeostasis maintenance, restored mitochondrial membrane potential (MMP), and reduced the SA-β-GAL accumulation in RPE. Furthermore, Arbutin alleviated oxidative stress-mediated cell apoptosis and senescence via activation of SIRT1, as evidenced by the increase of the downstream FoxO3a and PGC-1α/β that are related to mitochondrial biogenesis, and the suppression of NF-κB p65 inflammasome, whereas rehabilitation of oxidative stress by SIRT1 inhibitor attenuated the protective effect of Arbutin. In conclusion, we validated the results in an in vivo model constructed by NAIO₃-injured mice. OCT and HE staining showed that Arbutin sustained retinal integrity in the case of oxidative damage in vivo, and the disorder of RPE cytochrome was alleviated through fundus observation. In summary, our findings identified that oxidative stress-induced mitochondrial malfunction and the subsequent senescence acceleration in RPE cells, whereas Arbutin inhibited TBHP-induced RPE degeneration via regulating the SIRT1/Foxo3a/PGC-1α/β signaling pathway. These findings suggested that Arbutin is a new agent with potential applications in the development of AMD diseases.

Potential Utility of Natural Products against Oxidative Stress in Animal Models of Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune-mediated degenerative disease of the central nervous system (CNS) characterized by immune cell infiltration, demyelination and axonal injury. Oxidative stress-induced inflammatory response, especially the destructive effect of immune cell-derived free radicals on neurons and oligodendrocytes, is crucial in the onset and progression of MS. Therefore, targeting oxidative stress-related processes may be a promising preventive and therapeutic strategy for MS. Animal models, especially rodent models, can be used to explore the in vivo molecular mechanisms of MS considering their similarity to the pathological processes and clinical signs of MS in humans and the significant oxidative damage observed within their CNS. Consequently, these models have been used widely in pre-clinical studies of oxidative stress in MS. To date, many natural products have been shown to exert antioxidant effects to attenuate the CNS damage in animal models of MS. This review summarized several common rodent models of MS and their association with oxidative stress. In addition, this review provides a comprehensive and concise overview of previously reported natural antioxidant products in inhibiting the progression of MS.

Enzymatic Biosynthesis of Simple Phenolic Glycosides as Potential Anti-Melanogenic Antioxidants

Simple phenolics (SPs) and their glycosides have recently gained much attention as functional skin-care resources for their anti-melanogenic and antioxidant activities. Enzymatic glycosylation of SP aglycone make it feasible to create SP glycosides with updated bioactive potentials. Herein, a glycosyltransferase (GT)-encoding gene was cloned from the fosmid libraries of Streptomyces tenjimariensis ATCC 31603 using GT-specific degenerate PCR followed by in silico analyses. The recombinant StSPGT was able to flexibly catalyze the transfer of two glycosyl moieties towards two SP acceptors, (hydroxyphenyl-2-propanol [HPP2] and hydroxyphenyl-3-propanol [HPP3]), generating stereospecific α-anomeric glycosides as follows: HPP2-O-α-glucoside, HPP2-O-α-2″-deoxyglucoside, HPP3-O-α-glucoside and HPP3-O-α-2″-deoxyglucoside. This enzyme seems not only to prefer UDP-glucose and HPP2 as a favorable glycosyl donor and acceptor, respectively but also differentiates the positional difference of the hydroxyl function as acceptor catalytic sites. Paired in vitro and in vivo antioxidant assays represented SPs and their corresponding glycosides as convincing antioxidants in a time- and concentration-dependent manner by scavenging DPPH radicals and intracellular ROS. Even compared to the conventional agents, HPP2 and glycoside analogs displayed improved tyrosinase inhibitory activity in vitro and still suppressed in vivo melanogenesis. Both HPP2 glycosides are further likely to exert the best inhibitory activity against elastase, eventually highlighting these glycosides with enhanced anti-melanogenic and antioxidant activities as promising anti-wrinkle hits.

Modulatory Impact of Lamiaceae Metabolites on Apoptosis of Human Leukemia Cells

Lamiaceae species are rich sources of biologically active compounds which have been applied in medicine since ancient times. Especially their antineoplastic properties have been thoroughly studied with respect to their putative application in chemoprevention and adjuvant therapy of cancer. However, the most known biological effects of Lamiaceae have been ascribed to their essential oil fractions, whereas their (poly)phenolic metabolites being also abundant in these plants, are much less recognized, nevertheless contributing to their beneficial properties, such as anti-cancer actions. The aim of this study was to evaluate the impact of dried aqueous extracts from common thyme (Thymus vulgaris L.) (ExTv), wild thyme (Thymus serpyllum L.) (ExTs), sweet marjoram (Origanum majorana L.) (ExOm), and peppermint (Mentha × piperita L.) (ExMp), as well as (poly)phenolic compounds: caffeic acid (CA), rosmarinic acid (RA), lithospermic acid (LA), luteolin-7-O-β-glucuronide (Lgr), luteolin-7-O-rutinoside (Lr), eriodictyol-7-O-rutinoside (Er), and arbutin (Ab), on unstimulated Jurkat cells, in comparison with their effect on staurosporine-stimulated Jurkat cells. Jurkat T cells were incubated with different concentrations of ExTv, ExTs, ExOm, ExMp, Lgr, LA, Er, Lr, RA, CA, or Ab. Subsequently, staurosporine was added to half of the samples and flow cytometry combined with fluorescence-activated cell sorting analysis was conducted, which allowed for the selection of early and late apoptotic cells. Both ExTs and ExOm stimulated apoptosis of Jurkat cells and enhanced the proapoptotic effect of staurosporine. Conversely, ExTv and ExMp demonstrated no clear effect on apoptosis. CA and RA raised the staurosporine-induced apoptotic effect. The impact of Er and Lgr on Jurkat cells showed fluctuations depending on the compound concentration. Neither Er nor Ab altered staurosporine-induced apoptosis in Jurkat cells, whereas Lgr seemed to weaken the proapoptotic action of staurosporine. The most evident observation in this study was the pro-apoptotic action of ExTs and ExOm observed both in staurosporine-unstimulated and stimulated Jurkat cells. Additionally, an enhancement of staurosporine-induced apoptosis by caffeic and rosmarinic acids was reported. Therefore, it might be concluded that these are the mixtures of biologically active polyphenols which often exert more pronounced beneficial effects than purified molecules.

Recent Progress on Feasible Strategies for Arbutin Production

Arbutin is a hydroquinone glucoside and a natural product present in various plants. Arbutin potently inhibits melanin formation. This property has been exploited in whitening cosmetics and pharmaceuticals. Arbutin production relies mainly on chemical synthesis. The multi-step and complicated process can compromise product purity. With the increasing awareness of sustainable development, the current research direction prioritizes environment-friendly, biobased arbutin production. In this review, current strategies for arbutin production are critically reviewed, with a focus on plant extraction, chemical synthesis, biotransformation, and microbial fermentation. Furthermore, the bottlenecks and perspectives for future direction on arbutin biosynthesis are discussed.

Effects of arbutin on glucose uptake by glucose transporter 4 (GLUT4) and its cytoprotective properties in L6 skeletal muscle cell line

It has been well known that oxidative stress and increased intracellular reactive oxygen species (ROS) have a pivotal role in disrupting the insulin signaling pathways leading to cellular insulin resistance. In this study, we evaluated arbutin's effects on glucose uptake by GLUT4 and cytoprotective properties in the L6 skeletal muscle cell line. The effect of arbutin and tertiary butyl hydrogen peroxide (t-BHP) on glucose uptake in cultured L6 cells was investigated by flow cytometry. We also evaluated gene expression levels of GLUT1 and GLUT4 in the L6 cells by quantitative real-time polymerase chain reaction analysis. The results from the study demonstrated that the optimum ROS generation occurred 3 h after 100 µM t-BHP treatment and pretreatment with arbutin (500 and 1000 µM) significantly inhibited the t-BHP induced ROS generation (p < .05). Our result indicated that 3 h pretreatment of L6 cells with 1000 μM of arbutin before 50 μM t-BHP significantly increased glucose uptake than the 50 μM t-BHP alone group (p < .05). Our findings may suggest that an increase in the uptake of 2-NBDG by L6 cells with arbutin pretreatment can be associated with increased expression of GLUT4 and GLUT1 under oxidative stress.

Kojic Acid Showed Consistent Inhibitory Activity on Tyrosinase from Mushroom and in Cultured B16F10 Cells Compared with Arbutins

Kojic acid, β-arbutin, α-arbutin, and deoxyarbutin have been reported as tyrosinase inhibitors in many articles, but some contradictions exist in their differing results. In order to provide some explanations for these contradictions and to find the most suitable compound as a positive control for screening potential tyrosinase inhibitors, the activity and inhibition type of the aforementioned compounds on monophenolase and diphenolase of mushroom tyrosinase (MTYR) were studied. Their effects on B16F10 cells melanin content, tyrosinase (BTYR) activity, and cell viability were also exposed. Results indicated that α-arbutin competitively inhibited monophenolase activity, whereas they uncompetitively activated diphenolase activity of MTYR. β-arbutin noncompetitively and competitively inhibited monophenolase activity at high molarity (4000 µM) and moderate molarity (250–1000 µM) respectively, whereas it activated the diphenolase activity of MTYR. Deoxyarbutin competitively inhibited diphenolase activity, but could not inhibit monophenolase activity and only extended the lag time. Kojic acid competitively inhibited monophenolase activity and competitive–noncompetitive mixed-type inhibited diphenolase activity of MTYR. In a cellular experiment, deoxyarbutin effectively inhibited BTYR activity and reduced melanin content, but it also potently decreased cell viability. α-arbutin and β-arbutin dose-dependently inhibited BTYR activity, reduced melanin content, and increased cell viability. Kojic acid did not affect cell viability at 43.8–700 µM, but inhibited BTYR activity and reduced melanin content in a dose-dependent manner. Therefore, kojic acid was considered as the most suitable positive control among these four compounds, because it could inhibit both monophenolase and diphenolase activity of MTYR and reduce intercellular melanin content by inhibiting BTYR activity without cytotoxicity. Some explanations for the contradictions in the reported articles were provided.

Arbutin as a Skin Depigmenting Agent with Antimelanogenic and Antioxidant Properties

Arbutin is a compound of hydroquinone and D-glucose, and it has been over 30 years since there have been serious studies on the skin lightening action of this substance. In the meantime, there have been debates and validation studies about the mechanism of action of this substance as well as its skin lightening efficacy and safety. Several analogs or derivatives of arbutin have been developed and studied for their melanin synthesis inhibitory action. Formulations have been developed to improve the stability, transdermal delivery, and release of arbutin, and device usage to promote skin absorption has been developed. Substances that inhibit melanin synthesis synergistically with arbutin have been explored. The skin lightening efficacy of arbutin alone or in combination with other active ingredients has been clinically evaluated. Combined therapy with arbutin and laser could give enhanced depigmenting efficacy. The use of arbutin causes dermatitis rarely, and caution is recommended for the use of arbutin-containing products, especially from the viewpoint that hydroquinone may be generated during product use. Studies on the antioxidant properties of arbutin are emerging, and these antioxidant properties are proposed to contribute to the skin depigmenting action of arbutin. It is hoped that this review will help to understand the pros and cons of arbutin as a cosmetic ingredient, and will lead to future research directions for developing advanced skin lightening and protecting cosmetic products.

A comprehensive review of the therapeutic potential of curcumin nanoformulations

Today, due to the prevalence of various diseases such as the novel coronavirus (SARS-CoV-2), diabetes, central nervous system diseases, cancer, cardiovascular disorders, and so on, extensive studies have been conducted on therapeutic properties of natural and synthetic agents. A literature review on herbal medicine and commercial products in the global market showed that curcumin (Cur) has many therapeutic benefits compared to other natural ingredients. Despite the unique properties of Cur, its use in clinical trials is very limited. The poor biopharmaceutical properties of Cur such as short half-life in plasma, low bioavailability, poor absorption, rapid metabolism, very low solubility (at acidic and physiological pH), and the chemical instability in body fluids are major concerns associated with the clinical applications of Cur. Recently, nanoformulations are emerging as approaches to develop and improve the therapeutic efficacy of various drugs. Many studies have shown that Cur nanoformulations have tremendous therapeutic potential against various diseases such as SARS-CoV-2, cancer, inflammatory, osteoporosis, and so on. These nanoformulations can inhibit many diseases through several cellular and molecular mechanisms. However, successful long-term clinical results are required to confirm their safety and clinical efficacy. The present review aims to update and explain the therapeutic potential of Cur nanoformulations.