Surface-exposed chaperonin 60 derived from Propionibacterium freudenreichii MJ2 inhibits adipogenesis by decreasing the expression of C/EBPα/PPARγ.

Recent studies have shown that the health benefits of probiotics are not limited to those offered by living bacteria. It was reported that both live and killed cells of Propionibacterium freudenreichii MJ2 (MJ2) isolated from raw milk showed antiobesity activity in 3T3-L1 cells and high-fat diet-induced obese mice. This study was aimed at identifying the active component(s) responsible for the antiadipogenic activity of MJ2. Cell wall, surface protein, and cytoplasmic fractions of MJ2 were investigated for their inhibitory effects on adipogenesis in 3T3-L1 cells. Adipocytes treated with the surface protein fraction showed significantly lower lipid accumulation. Using the MASCOT algorithm following LC-MS/MS analysis, 131 surface proteins were identified and they were principally classified into three categories (network clusters related to ribosomes, carbon metabolism, and chaperones). Among them, chaperonin 60 (Cpn60) was selected as a potential candidate protein. Cpn60 inhibited lipid accumulation and adipogenesis during the early period of differentiation (days 0-2) and decreased expression of genes related to adipogenesis (Pparg and Cebpa) and lipogenesis (Fas and Scd1). The expression of Gata2/3, which suppresses adipogenesis, significantly increased in Cpn60-treated cells. Moreover, the nuclear translocation of C/EBPß was inhibited by Cpn60 treatment. In conclusion, Cpn60, a surface protein in MJ2, shows antiadipogenic activity by reducing the expression of C/EBPß through the upregulation of Gata2/3 expression followed by downregulation of Pparg and Cebpa expression.

Anti-asthma and antitussive effects of a fermented extract of a mixture of Ramulus mori, Anthriscus sylvestris, and Salvia plebeian.

Respiratory immunity is getting more important recently due to outbreak of respiratory diseases and increasing the concentration of fine dust. The aim of this study was to investigate respiratory protection effect of a fermented extract of medicinal plants (FEMP) containing Ramulus mori, Salvia plebeia, and Anthriscus sylvestris. The expression levels of IL-8 and IL-17 in LPS/poly-L-arginine (PLA) and FEMP-cotreated A549 cells were lower than those in LPS/PLA only-treated cells. The levels of IgE, IL-17, and IL-4 in the bronchoalveolar lavage fluid (BALF) and serum of FEMP-treated mice with ovalbumin/LPS-induced asthma were lower than the control levels. The lung inflammation score and the number of inflammatory cells in the BALF decreased by FEMP treatment. In the citric acid-induced coughing guinea pig, the FEMP treatment decreased the number of coughs. Therefore, FEMP shows anti-asthmatic and antitussive activities without hepatotoxicity and can be used as a compound aiming to improve respiratory health. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10068-021-00955-3.

Oxyresveratrol Ameliorates Dextran Sulfate Sodium-Induced Colitis in Rats by Suppressing Inflammation.

Colitis causes destruction of the intestinal mucus layer and increases intestinal inflammation. The use of antioxidants and anti-inflammatory agents derived from natural sources has been recently highlighted as a new approach for the treatment of colitis. Oxyresveratrol (OXY) is an antioxidant known to have various beneficial effects on human health, such as anti-inflammatory, antibacterial activity, and antiviral activity. The aim of this study was to investigate the therapeutic effect of OXY in rats with dextran sulfate sodium (DSS)-induced acute colitis. OXY ameliorated DSS-induced colitis and repaired damaged intestinal mucosa. OXY downregulated the expression of pro-inflammatory cytokine genes (TNF-α, IL-6, and IL-1ß) and chemokine gene MCP-1, while promoting the production of anti-inflammatory cytokine IL-10. OXY treatment also suppressed inflammation via inhibiting cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression in the colon, as well as the activity of myeloperoxidase (MPO). OXY exhibited anti-apoptotic effects, shifting the Bax/Bcl-2 balance. In conclusion, OXY might improve DSS-induced colitis by restoring the intestinal mucus layer and reducing inflammation within the intestine.

Efficacy of Ethanolic Extract of Opuntia ficus-indica var. saboten Stems for Improving Cognitive Function in Elderly Subjects 55-85 Years of Age: A Randomized, Double-Blind, Placebo-Controlled Study.

Many natural compounds have been reported to improve cognitive function in cell- and animal-based studies. In this clinical trial, we evaluated the efficacy of ethanolic extract of Opuntia ficus-indica var. saboten stem for improving cognitive function using a randomized, double-blind, placebo-controlled trial (n = 81) in aged people. After 12 weeks of administration of OFE (a mixture of ethanolic extract of O. ficus-indica var. Saboten stem and dextrin) or placebo, the effect on cognitive function was assessed. Overall, OFE did not show a significant difference from the placebo in terms of efficacy. However, the cognitive function significantly improved in the OFE group compared with the placebo group in the subgroup ≤70 years of age, which means that the effect of OFE administration exhibits an age-dependent effect. In addition, the safety of OFE was confirmed by analyzing blood test results, vital signs, and electrocardiograms. In conclusion, OFE administration in participants ≤70 years of age shows a positive effect on overall cognitive function. The trial was registered on CRIS (the Clinical Research Information Service), administered by the Korea Centers for Disease Control & Prevention (Registration Number: KCT0003766; URL: https://cris.nih.go.kr/cris/en/search/search_result_st01.jsp?seq=12957).

Fermented Platycodon grandiflorum Extracts Relieve Airway Inflammation and Cough Reflex Sensitivity In Vivo.

Platycodon grandiflorum (PG) has been extensively utilized as an herb to relieve phlegm. In this study, the effects of PG root extracts on airway inflammation and cough reflex were investigated, especially using fermented PG extracts (FPE) to increase an active compound, platycodin D by fermentation. FPE significantly reduced the numbers of eosinophils and total cells in the bronchoalveolar lavage fluid (BALF) obtained from lipopolysaccharide/ovalbumin (LPS/OVA)-induced asthma mice versus those of vehicle control. Moreover, in the BALF and the serum, FPE significantly reduced the concentration of IL-17E, a proinflammatory cytokine that causes TH2 immunity, including eosinophil amplification. It was also demonstrated that FPE might relieve inflammations through histological analysis of the lung separated from each mouse. Furthermore, in cough reflex guinea pigs induced by citric acid treatment, FPE treatment significantly reduced the number of coughs versus that of vehicle control, and consequently decreased cough reflex sensitivity. In addition, the total cell number and eosinophils significantly decreased in the BALF obtained from each guinea pig versus that of vehicle control. In in vitro study, pretreatment with FPE in LPS-stimulated RAW264.7 cells significantly reduced the levels of proinflammatory cytokines such as TNF-α, IL-6, and IL-1ß, and inducible nitric oxide synthases (iNOS). Therefore, we demonstrated that FPE relieved airway inflammation and cough reflex sensitivity in vivo, and exhibited anti-inflammatory effects through suppression of iNOS and several proinflammatory cytokines. These findings suggest that FPE might have a beneficial effect on respiratory health, and may be useful as a functional food to prevent respiratory diseases.

Gamma Aminobutyric Acid Increases Absorption of Glycine-Bound Iron in Mice with Iron Deficiency Anemia.

Iron deficiency is a leading cause of anemia. Amino acids are known to promote the absorption of both soluble and insoluble iron. The bioavailability of organic iron is higher than that of inorganic iron. Therefore, the aim of this study was to evaluate the iron absorption of glycine-bound iron (an organic iron) and a combination of glycine-bound iron and gamma aminobutyric acid (GABA) in mice with iron deficiency anemia (IDA). Mice were fed an iron-deficient diet for 3 weeks, followed by oral administration of GABA, inorganic iron, glycine-bound iron, or GABA plus glycine-bound iron for 5 weeks. Ferritin storage in the spleen was measure by immunohistochemistry (IHC). Iron deposition in the liver and spleen tissues was analyzed using atomic absorption spectrometry. Expression levels of iron absorption-related genes were measured by quantitative real-time polymerase chain reaction (qPCR). Iron absorption was enhanced in the glycine-bound iron-treated group compared with the inorganic iron-treated group. Hemoglobin, serum Fe, ferritin, and liver iron levels did not increase in mice treated with GABA alone. However, mice administered GABA in combination with glycine-bound iron showed higher iron absorption than those administered organic iron alone. Our results indicate that glycine-bound iron in combination with GABA might exert a synergistic effect on iron absorption and bioavailability, suggesting that the addition of GABA to existing iron supplements might increase their effectiveness for treating IDA.

Antiobesity effect of ethanolic extract of Ramulus mori in differentiated 3T3-L1 adipocytes and high-fat diet-induced obese mice.

ETHNOPHARMACOLOGICAL RELEVANCE: The mulberry (Morus alba L.) is a plant that mainly grows in East Asian countries such as Korea and China and has been used as a folk remedy for improving inflammation, cancer, and diabetes. Ramulus mori, the twig of Morus alba L., is known as "sangzhi" or "ppongnamugazhi" in Korea and used as a traditional medicine. Moreover, its effective compounds show some health benefits such as cholesterol reduction and attenuation of acute colitis. AIM OF THE STUDY: As the number of obese people is increasing worldwide, the demand for diet drugs or products to treat obesity is also increasing. In this study, we investigated the antiobesity effect of the ethanolic extract of Ramulus mori (ERM) using differentiated 3T3-L1 adipocytes and a high-fat diet (HFD)-induced obese mouse model. METHODS: The expression levels of genes and proteins related to adipogenesis, lipogenesis, and lipolysis were analyzed by quantitative real-time PCR (qPCR) and western blot, respectively. Oil red O staining was carried out to determine the amount of neutral lipids deposited in the liver. RESULTS: Compared with the ERM-untreated group, the ERM-treated groups exhibited reduced expression levels of genes involved in adipogenesis and lipogenesis in differentiated adipocytes and in HFD-induced obese mice, while the expression levels of genes involved in lipolysis increased. The administration of ERM to HFD-induced obese mice reduced the body weight, liver weight, and epididymal adipose tissue weight. Compared with the untreated HFD-induced obese mice, the ERM-treated mice exhibited decreased serum lipid levels. ERM treatment also reduced lipid accumulation in the liver, which was confirmed by oil red O staining. CONCLUSION: ERM has the potential to be an effective natural material for reducing obesity.

An oral toxicity test in rats and a genotoxicity study of extracts from the stems of Opuntia ficus-indica var. saboten.

BACKGROUND: Opuntia ficus-indica var. saboten (OFIS) is used widely in Korea to treat constipation due to its diuretic effects and its enhancement of bowel function and appetite. However, its safety has not yet been established. The aim of this study was to evaluate the repeated oral toxicity and genotoxicity of OFIS extract (OE). METHODS: White female and male Sprague Dawley rats (n = 6) were divided into 4 groups, and OE was administered to them orally (0, 500, 1000, and 2000 mg/kg/day, respectively) for one week. The Ames test, the chromosomal aberration assay, and the mammalian micronucleus test were performed to determine the OE genotoxicity. The Ames test was conducted using Salmonella typhimurium (S. typhimurium) strains TA100, TA1535, TA98, and TA153 and Escherichia coli (E. coli) WP2 urvA, and Chinese hamster lung (CHL) cells were used for the chromosomal aberration assay. The mammalian micronucleus test was performed using mouse bone marrow cells. RESULTS: This study revealed that OE administration did not alter the normal rat behavior, body weight gain, and food and water consumption with respect to the normal controls. In addition, there were no toxic effects observed during the ophthalmological test. The biochemical hematological and serum values as well as urinalysis parameters and organ weights were all similar to those of the normal control group. In addition, no mutagenicity effects from the OE were found in S. typhimurium or E. coli with or without S9 activation according to the Ames test. The OE did not significantly alter the number of structural aberrations in the CHL cells in the presence or absence of S9 activation. The oral administration of OE also caused no significant increase in the number of micronucleated polychromatic erythrocytes or in the mean ratio of polychromatic to total erythrocytes. CONCLUSIONS: In conclusion, OE could be considered as a reliable and safe herbal medicine or functional food since no toxicity was found under the conditions of this study.

Oxyresveratrol stimulates mucin production in an NAD+-dependent manner in human intestinal goblet cells.

The intestinal mucus layer plays an important role in the management of inflammatory bowel disease. The aim of this study was to investigate the effects of oxyresveratrol (OXY), an antioxidant, on the stimulation of mucin production in human LS 174T goblet cells and the underlying mechanism thereof. OXY increased MUC2 expression at both the mRNA and protein levels. By performing two-dimensional gel electrophoresis, we found that the expression of nicotinic acid phosphoribosyltransferase1 (NaPRT1) in OXY-treated LS 174T cells was greatly increased compared with that in negative control cells. In addition, the NAD+/NADH ratio was increased in proportion to OXY in LS 174T cells. The expression of NAD+-synthesis enzymes, NaPRT1, nicotinamide riboside kinase1 (NRK1) and nicotinamide mononucleotide adenylyltransferase1 (Nmnat1) was significantly increased at both the mRNA and protein levels in OXY-treated LS 174T cells. The inhibition of NaPRT1 and NRK1 did not decrease MUC2 expression after inhibiting by small interfering RNA (siRNA)-NaPRT1 and siRNA-NRK1, respectively; however, inhibition of Nmnat by an Nmnat inhibitor decreased MUC2 expression in a dose-dependent manner. In conclusion, OXY increases NAD+ levels, resulting in the stimulation of MUC2 expression in LS 174T cells. These findings present a novel role for NAD+ in stimulation of MUC2 expression.

Oxyresveratrol improves tight junction integrity through the PKC and MAPK signaling pathways in Caco-2 cells.

Strengthening intestinal tight junctions (TJ) provides an effective barrier from the external environment and is important for recovery from inflammatory bowel disease. Oxyresveratrol (OXY), an isomer of hydroxylated resveratrol, is isolated from many plants. The aim of this study was to investigate the effect of OXY on intestinal TJ and to elucidate the mechanism underlying the OXY-mediated increase in TJ integrity in human intestinal Caco-2 cells. OXY-treated Caco-2 cell monolayers showed decreased monolayer permeability as evaluated by paracellular transport assay. The results showed that OXY significantly increased the levels of TJ-related genes and proteins (Claudin-1, Occludin and ZO-1) compared with those of the negative control. OXY activated protein kinase C (PKC) and increased expression levels of mitogen-activated protein kinase (MAPK) genes. OXY also increased gene and protein levels of the transcription factor Cdx-2. Expression levels of TJ, PKC and Cdx-2 proteins and transepithelial electrical resistance (TEER) value decreased in OXY-treated Caco-2 cells following treatment with a pan-PKC inhibitor compared with those of the untreated control. In conclusion, OXY strengthens the integrity of the intestinal TJ barrier via activation of the PKC and MAPK pathways.

Conditioned medium from LS 174T goblet cells treated with oxyresveratrol strengthens tight junctions in Caco-2 cells.

BACKGROUND: Strengthening of intestinal tight junctions provides an effective barrier from the external environment. Goblet cell-derived trefoil factor 3 (TFF3) increases transepithelial resistance by upregulating the expression of tight junction proteins. Oxyresveratrol (OXY) is a hydroxyl-substituted stilbene found in the roots, leaves, stems, and fruit of many plants and known to have various biological activities. In this study, we investigated the strengthening effect of OXY on intestinal tight junctions through stimulation of TFF production in goblet cells. METHODS: We prepared conditioned medium from LS 174T goblet cells treated with OXY (GCO-CM) and investigated the effect of GCO-CM on strengthening tight junctions of Caco-2 cells. The mRNA and protein expression levels of major tight junction components (claudin-1, occludin, and ZO-1) were measured by quantitative real-time PCR and western blotting, respectively. Transepithelial electric resistance (TEER) was measured using an ohm/V meter. Monolayer permeability was evaluated by paracellular transport of fluorescein isothiocyanate-dextran. RESULTS: OXY showed a strong antioxidant activity. It significantly increased the expression level of TFF3 in LS 174T goblet cells. GCO-CM prepared by treatment with 2.5, 5, and 10µg/ml OXY did not show cytotoxicity in Caco-2 cells. GCO-CM increased the mRNA and protein expression levels of claudin-1, occludin, and ZO-1. It also significantly increased tight junction integrity and reduced permeability in a dose-dependent manner. CONCLUSION: OXY stimulates the expression of TFF3 in goblet cells, which might increase the integrity of the intestinal tight junction barrier.

Brief Communication: SIR-2.1-dependent lifespan extension of Caenorhabditis elegans by oxyresveratrol and resveratrol.

Resveratrol (RES) has been studied for its effects on the lifespan extension of Caenorhabditis elegans, but controversy still remains on its mechanism related with SIR-2. In this study, longevity assay was performed to confirm SIR-2-dependent lifespan extension of C. elgeans with RES and oxyresveratrol (OXY), an isomer of hydroxylated RES using loss-of-function mutants of C. elegans including sir-2.1 mutant. The results showed that OXY and RES significantly (P < 0.05) extended the lifespan of C. elegans compared with the control. OXY and RES also significantly (P < 0.05) increased the mRNA expression levels of sir-2.1 and aak-2 in a dose-dependent manner and increased the protein expression levels of SIR-2.1. OXY and RES treatment extended the lifespan in daf-16 loss-of-function mutants, which suggested that lifespan extension was not occurring via the activation of DAF-16. However, OXY and RES failed to extend the lifespan in loss-of-function mutants of sir-2.1 and aak-2 Therefore, OXY and RES extend the lifespan of C. elegans by overexpression of SIR-2.1, which is related to lifespan extension through calorie restriction and the AMP-activated protein kinase (AMPK) pathway, although this process is independent of the FOXO/DAF-16 pathway.

Bee Venom Promotes Hair Growth in Association with Inhibiting 5α-Reductase Expression.

Alopecia is an important issue that can occur in people of all ages. Recent studies show that bee venom can be used to treat certain diseases including rheumatoid arthritis, neuralgia, and multiple sclerosis. In this study, we investigated the preventive effect of bee venom on alopecia, which was measured by applying bee venom (0.001, 0.005, 0.01%) or minoxidil (2%) as a positive control to the dorsal skin of female C57BL/6 mice for 19 d. Growth factors responsible for hair growth were analyzed by quantitative real-time PCR and Western blot analysis using mice skins and human dermal papilla cells (hDPCs). Bee venom promoted hair growth and inhibited transition from the anagen to catagen phase. In both anagen phase mice and dexamethasone-induced catagen phase mice, hair growth was increased dose dependently compared with controls. Bee venom inhibited the expression of SRD5A2, which encodes a type II 5α-reductase that plays a major role in the conversion of testosterone into dihydrotestosterone. Moreover, bee venom stimulated proliferation of hDPCs and several growth factors (insulin-like growth factor 1 receptor (IGF-1R), vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF)2 and 7) in bee venom-treated hDPCs dose dependently compared with the control group. In conclusion, bee venom is a potentially potent 5α-reductase inhibitor and hair growth promoter.

An ethanol extract of Ramulus mori improves blood circulation by inhibiting platelet aggregation.

Inappropriate platelet aggregation can cause blood coagulation and thrombosis. In this study, the effect of an ethanol extract of Ramulus mori (ERM) on blood circulation was investigated. The antithrombotic activity of ERM on rat carotid arterial thrombosis was evaluated in vivo, and the effect of ERM on platelet aggregation and blood coagulation time was evaluated ex vivo. To evaluate the safety of ERM, its cytotoxicity to platelets and its effect on tail bleeding time were assessed; ERM was not toxic to rat platelets and did not prolong bleeding time. Moreover, administering ERM to rats had a significant preventive effect on carotid arterial thrombosis in vivo, and significantly inhibited adenosine diphosphate- and collagen-induced platelet aggregation ex vivo, whereas it did not prolong coagulation periods, such as prothrombin time and activated partial thromboplastin time. The results suggest that ERM is effective in improving blood circulation via antiplatelet activity rather than anticoagulation activity.

Antihyperlipidemic effects of rhapontin and rhapontigenin from rheum undulatum in rats fed a high-cholesterol diet.

Rhapontin was purified from a methanol extract from the roots of Rheum undulatum, and rhapontigenin was produced by an enzymatic transformation of rhapontin. Rats were fed a high-cholesterol diet to induce hyperlipidemia, followed by oral treatment with rhapontin or rhapontigenin (1-5 mg/kg/day). Rhapontin and rhapontigenin treatment resulted in a significant (p<0.05) dose-dependent decrease in the serum lipid level, while the high-density lipoprotein cholesterol level increased slightly compared with the experimental control. Furthermore, rhapontin and rhapontigenin treatment improved the pathological characteristics of the degenerating fatty liver in high-cholesterol diet-induced hyperlipidemic rats dose-dependently. Aspartate aminotransferase and alanine aminotransferase levels in rhapontin- and rhapontigenin-treated hyperlipidemic rats were not significantly different from those in the control. These results indicate that rhapontin and rhapontigenin can be used as potent antihyperlipidemic agents.

Antihyperlipidemic effects of stilbenoids isolated from Morus alba in rats fed a high-cholesterol diet.

Mulberroside A (MUL) was purified from an ethanol extract of Morus alba root, and oxyresveratrol (OXY) was produced by enzymatic conversion of MUL. Normal rats, Triton WR-1339-induced hyperlipidemic rats, and high-cholesterol diet (HCD)-induced hyperlipidemic rats were orally treated with MUL or OXY (1-5mg/kg/day). MUL and OXY were administered 1h prior to concomitant treatment with Triton WR-1339 for a further 24h, whereas the drugs were administered concurrently with HCD for 4weeks. Oral MUL and OXY pre-treatment vs. water pre-treatment of Triton WR-1339-induced hyperlipidemic rats significantly (p<0.05) reduced the levels of serum lipids in a dose-dependent manner, while high-density lipoprotein cholesterol (HDL-C, or "good" cholesterol) levels were increased. Oral MUL and OXY treatment of HCD-fed rats also showed a significant (p<0.05) dose-dependent decrease in serum lipids, coronary artery risk index (CRI), and atherogenic index (AI), but not HDL-C. Furthermore, MUL and OXY treatment of HCD-induced hyperlipidemic rats demonstrated a significant dose-dependent improvement in the histological features of hepatic fatty degeneration. Aspartate aminotransferase and alanine aminotransferase values in OXY-treated normal rats were not significantly different from those in water-treated control rats. These results indicate that MUL and OXY might be developed as novel antihyperlipidemic agents.

Effect of water-soluble fraction of cherry tomatoes on the adhesion of probiotics and Salmonella to intestinal epithelial cells.

BACKGROUND: Tomato is one of the most consumed vegetables in the world and contains many valuable nutritional components. Here we investigate the prebiotic effects of cherry tomatoes for improving gut health. RESULTS: Water-soluble dietary fiber was prepared from fresh and processed (heat treatment at 80 °C for 15 min) cherry tomato samples, each with and without Viscozyme L treatment. In the adhesion assays, all water-soluble dietary fiber samples improved adhesion of probiotics (Lactobacillus rhamnosus and Bifidobacterium bifidum) to intestinal epithelial cells (Caco-2 cells). Heat treatment in the preparation of juice from cherry tomatoes showed no significant effect on the adhesion of probiotics to Caco-2 cells. The oligofructose content of samples affected the intestinal adhesion of probiotic bacteria, with higher oligosaccharide concentrations associated with greater adhesion of probiotics and more inhibition of the adhesion of pathogens to Caco-2 cells. CONCLUSION: The present results suggest that cherry tomato can act as a prebiotic, with oligofructose potentially being one of its major prebiotic components.

Evaluation of the inhibition of mushroom tyrosinase and cellular tyrosinase activities of oxyresveratrol: comparison with mulberroside A.

The inhibitory effects of oxyresveratrol, the aglycone of mulberroside A, on mushroom and cellular tyrosinase activities and melanin synthesis were evaluated. Mulberroside A and oxyresveratrol showed inhibitory activity against mushroom tyrosinase, with oxyresveratrol demonstrating a greater inhibitory effect than that of mulberroside A. Oxyresveratrol and mulberroside A strongly inhibited melanin production in Streptomyces bikiniensis and exhibited dose-dependent inhibition of tyrosinase activity and inhibition of melanin synthesis in B16F10 melanoma cells. However, the compounds exhibited nearly similar inhibitory effects on the activity of cellular tyrosinase and melanin synthesis in murine melanocytes. The inhibition of melanin synthesis by mulberroside A and oxyresveratrol was involved in suppressing the expression level of melanogenic enzymes, tyrosinase, tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2). These results indicate that the inhibition rate of mushroom tyrosinase might not provide an accurate estimate of the inhibition rate of melanin synthesis in melanocytes.

Inhibitory effect of mulberroside A and its derivatives on melanogenesis induced by ultraviolet B irradiation.

Mulberroside A was isolated from the ethanol extract of Morus alba roots. The enzymatic hydrolysis of mulberroside A with Pectinex produced oxyresveratrol and oxyresveratrol-3-O-glucoside. We tested oxyresveratrol, oxyresveratrol-3-O-glucoside, and mulberroside A to determine whether they could inhibit ultraviolet B (UVB) irradiation-induced melanogenesis in brown guinea pig skin. Topical application of mulberroside A, oxyresveratrol, and oxyresveratrol-3-O-glucoside reduced the pigmentation in guinea pig skin. These compounds suppressed the expression of melanogenic enzymes tyrosinase, tyrosinase-related protein-1, and microphthalmia transcription factor. The anti-melanogenesis effect was highest with oxyresveratrol, intermediate with oxyresveratrol-3-O-glucoside, and lowest with mulberroside A. Mulberroside A is a glycosylated stilbene of oxyresveratrol; thus, the deglycosylation of mulberroside A resulted in enhanced inhibition of melanogenesis. Histological analysis with Fontana-Masson staining confirmed that these compounds significantly reduced the melanin content in the epidermis of UVB-irradiated guinea pig skin compared to the vehicle control. Thus, these compounds effectively reduced pigmentation and may be suitable cosmetic agents for skin whitening.

Biotransformation of mulberroside A from Morus alba results in enhancement of tyrosinase inhibition.

Mulberroside A, a glycosylated stilbene, was isolated and identified from the ethanol extract of the roots of Morus alba. Oxyresveratrol, the aglycone of mulberroside A, was produced by enzymatic hydrolysis of mulberroside A using the commercial enzyme Pectinex. Mulberroside A and oxyresveratrol showed inhibitory activity against mushroom tyrosinase with an IC(50) of 53.6 and 0.49 microM, respectively. The tyrosinase inhibitory activity of oxyresveratrol was thus approximately 110-fold higher than that of mulberroside A. Inhibition kinetics showed mulberroside A to be a competitive inhibitor of mushroom tyrosinase with L-tyrosine and L-DOPA as substrate. Oxyresveratrol showed mixed inhibition and noncompetitive inhibition against L-tyrosine and L-DOPA, respectively, as substrate. The results indicate that the tyrosinase inhibitory activity of mulberroside A was greatly enhanced by the bioconversion process.