Antinociceptive Effect of Dendrobii caulis in Paclitaxel-Induced Neuropathic Pain in Mice.

Paclitaxel-induced neuropathic pain (PINP) is a serious adverse effect of chemotherapy. Dendrobii caulis (D. caulis) is a new food source used as herbal medicine in east Asia. We examined the antinociceptive effects of D. caulis extract on PINP and clarified the mechanism of action of transient receptor potential vanilloid 1 receptor (TRPV1) in the spinal cord. PINP was induced in male mice using multiple intraperitoneal injections of paclitaxel (total dose, 8 mg/kg). PINP was maintained from D10 to D21 when assessed for cold and mechanical allodynia. Oral administration of 300 and 500 mg/kg D. caulis relieved cold and mechanical allodynia. In addition, TRPV1 in the paclitaxel group showed increased gene and protein expression, whereas the D. caulis 300 and 500 mg/kg groups showed a significant decrease. Among various substances in D. caulis, vicenin-2 was quantified by high-performance liquid chromatography, and its administration (10 mg/kg, i.p.) showed antinociceptive effects similar to those of D. caulis 500 mg/kg. Administration of the TRPV1 antagonist capsazepine also showed antinociceptive effects similar to those of D. caulis, and D. caulis is thought to exhibit antinociceptive effects on PINP by modulating the spinal TRPV1.

The effect of ginger extract on cisplatin-induced acute anorexia in rats.

Cisplatin is a platinum-based chemotherapeutic agent widely used to treat various cancers. However, several side effects have been reported in treated patients. Among these, acute anorexia is one of the most severe secondary effects. In this study, a single oral administration of 100 or 500 mg/kg ginger extract (GE) significantly alleviated the cisplatin-induced decrease in food intake in rats. However, these body weight and water intake decreases were reversed in the 100 mg/kg group rats. To elucidate the underlying mechanism of action, serotonin (5-HT) and 5-HT2C, 3A, and 4 receptors in the nodose ganglion of the vagus nerve were investigated. The results showed that cisplatin-induced increases in serotonin levels in both the blood and nodose ganglion tissues were significantly decreased by100 and 500 mg/kg of GE administration. On 5-HT receptors, 5-HT3A and 4, but not 2C receptors, were affected by cisplatin, and GE 100 and 500 mg/kg succeeded in downregulating the evoked upregulated gene of these receptors. Protein expression of 5-HT3A and 4 receptors were also reduced in the 100 mg/kg group. Furthermore, the injection of 5-HT3A, and 4 receptors antagonists (palonostron, 0.1 mg/kg, i.p.; piboserod, 1 mg/kg, i.p., respectively) in cisplatin treated rats prevented the decrease in food intake. Using high-performance liquid chromatography (HPLC) analysis, [6]-gingerol and [6]-shogaol were identified and quantified as the major components of GE, comprising 4.12% and 2.15% of the GE, respectively. Although [6]-gingerol or [6]-shogaol alone failed to alleviate the evoked anorexia, when treated together, the effect was significant on the cisplatin-induced decrease in food intake. These results show that GE can be considered a treatment option to alleviate cisplatin-induced anorexia.

Phlomidis Radix Extract Alleviates Paclitaxel-Induced Neuropathic Pain by Modulating Spinal TRPV1 in Mice.

Paclitaxel is a chemotherapeutic drug reported to have excellent activity against tumors; however, various side effects, including peripheral neuropathy, limit its use in some cases. In this study, the effect of Phlomidis radix (P.Radix) extract was assessed on paclitaxel-induced cold and mechanical peripheral neuropathy in mice. Multiple paclitaxel injections (accumulative dose of 8 mg/kg, i.p.) induced increased behavioral responses to cold and mechanical stimuli in mice from D10 to D21 after the first paclitaxel injection. Cold and mechanical stimuli were performed by acetone drop and von Frey filament, respectively. Oral administrations of 25% ethanol extract of P.Radix (300 and 500 mg/kg) relieved cold and mechanical pain in a dose-dependent manner. Furthermore, among the various transient receptor potential (TRP) cation channel subfamilies, paclitaxel upregulated the spinal gene expression of transient receptor potential vanilloid 1 (TRPV1) and melastatin 4 (TRPM4), but not ankyrin 1 (TRPA1). However, 500 mg/kg but not 300 mg/kg of P.Radix extract significantly downregulated the gene expression of TRPV1 but not TRPM4. Among the components of P.Radix, sesamoside was identified and quantified by high-performance liquid chromatography (HPLC), and the administration of sesamoside (7.5 mg/kg, i.p.) showed a similar analgesic effect to 300 mg/kg P.Radix. These results suggest that P.Radix and sesamoside should be considered when treating paclitaxel-induced neuropathic pain.

Involvement of the Spinal Serotonergic System in the Analgesic Effect of [6]-Shogaol in Oxaliplatin-Induced Neuropathic Pain in Mice.

Oxaliplatin is a chemotherapy drug that can induce severe acute neuropathy in patients within hours of treatment. In our previous study, 10 mg/kg [6]-shogaol (i.p.) significantly alleviated cold and mechanical allodynia induced by a 6 mg/kg oxaliplatin injection (i.p.); however, the precise serotonin-modulatory effect has not been investigated. In this study, we showed that intrathecal injections of NAN-190 (5-HT1A receptor antagonist, 1 µg) and MDL-72222 (5-HT3 receptor antagonist, 15 µg), but not ketanserin (5-HT2A receptor antagonist, 1 µg), significantly blocked the analgesic effect of [6]-shogaol (10 mg/kg, i.p.). Furthermore, the gene expression of the serotonin-synthesizing enzyme tryptophan hydroxylase 2 (TPH2) and serotonin levels in the spinal cord and serum were significantly downregulated (p < 0.0001 and p = 0.0002) and upregulated (p = 0.0298 and p = 0.0099) after oxaliplatin and [6]-shogaol administration, respectively. Moreover, both the gene and protein expression of the spinal serotonin receptors 5-HT1A and 5-HT3 significantly increased after [6]-shogaol injections (p < 0.0001). Finally, intrathecal injections of both receptor agonists (8-OH-DPAT; 5-HT1A receptor agonist, 10 µg and m-CPBG; 5-HT3 receptor agonist, 15 µg) mimicked the effects of [6]-shogaol in oxaliplatin-injected mice. Taken together, these results demonstrate that [6]-shogaol attenuates oxaliplatin-induced neuropathic pain by modulating the spinal serotoninergic system.

Red Ginger Extract Prevents the Development of Oxaliplatin-Induced Neuropathic Pain by Inhibiting the Spinal Noradrenergic System in Mice.

Oxaliplatin is a well-known chemotherapeutic drug that is widely used to treat colorectal cancer. However, it can induce acute side effects in up to 90% of patients. Serotonin and norepinephrine reuptake inhibitors (SNRIs) are used as first-choice drugs; however, even SNRIs are known to be effective only in treatment and not for prevention. Therefore, finding a drug that can prevent the development of cold and mechanical forms of allodynia induced by oxaliplatin is needed. This study demonstrated that multiple oral administrations of 100 mg/kg and 300 mg/kg of red ginger extract could significantly prevent pain development in mice. The role of the noradrenergic system was investigated as an underlying mechanism of action. Both the spinal α1- and α2-adrenergic receptors were significantly downregulated after treatment. Furthermore, the noradrenaline levels in the serum and spinal cord were upregulated and downregulated after treatment with paclitaxel and red ginger, respectively. As the active sub-component of red ginger, ginsenoside Rg3 (Rg3) was identified and quantified using HPLC. Moreover, multiple intraperitoneal injections of Rg3 prevented the development of pain in paclitaxel-treated mice, suggesting that RG3 may induce the effect of red ginger extract.

Effects of gamma aminobutyric acid on performance, blood cell of broiler subjected to multi-stress environments.

OBJECTIVE: Stress factors such as high temperatures, overcrowding, and diurnal temperature range exert profound negative effects on weight gain and productivity of broiler chickens. The potential of gamma aminobutyric acid (GABA) as an excitatory neurotransmitter was evaluated under various stress conditions in this study. METHODS: The experiment was conducted under four different environmental conditions: normal, high temperature, overcrowded, and in an overcrowded-diurnal temperature range. The experimental groups were divided into (-) control group without stress, (+) control group with stress, and G50 group (GABA 50 mg/kg) with stress. Weight gain, feed intake, and feed conversion ratio were measured, and stress reduction was evaluated through hematologic analysis. RESULTS: The effects of GABA on broilers in four experimental treatments were evaluated. GABA treated responded to environmental stress and improved productivity in all the experimental treatments. The magnitude of stress observed was highest at high temperature, followed by the overcrowded environment, and was least for the overcrowded-diurnal temperature range. CONCLUSION: Various stress factors in livestock rearing environment can reduce productivity and increase disease incidence and mortality rate. To address these challenges, GABA, an inhibitory neurotransmitter, was shown to reduce stress caused due to various environmental conditions and improve productivity.

Anti-adipogenic Effects of Sulforaphane-rich Ingredient with Broccoli Sprout and Mustard Seed in 3T3-L1 Preadipocytes.

Glucoraphanin (GRA) is a precursor of sulforaphane (SFN), which can be synthesized by the enzyme myrosinase. In this study, we developed and validated HPLC analytical methods for the determination of GRA and SFN in mustard seed powder (MSP), broccoli sprout powder (BSP), and the MSP-BSP mixture powder (MBP), and evaluated their anti-adipogenic effects in 3T3-L1 adipocytes. We found that the analysis methods were suitable for the determination of GRA and SFN in MSP, BSP, and MBP. The content of GRA in BSP was 131.11 ± 1.84 µmol/g, and the content of SFN in MBP was 162.29 ± 1.24 µmol/g. In addition, BSP and MBP effectively decreased lipid accumulation content without any cytotoxicity. Both BSP and MBP significantly inhibited the expression of adipogenic proteins and increased the expression of proteins related to lipolysis and lipid metabolism. BSP and MBP inhibited the expression of adipocyte protein 2 (aP2), CCAAT/enhancer-binding protein-α (C/EBP-α), and peroxisome proliferator-activated receptor-γ (PPAR-γ) in 3T3-L1 adipocytes, and inhibited the expression of fatty acid synthase (FAS) through AMP-activated protein kinase (AMPK). Meanwhile, BSP and MBP also increased the expression of the lipolysis-related proteins, uncoupling protein-1 (UCP-1) and carnitine palmitoyltransferase-1 (CPT-1). Moreover, MBP exerted anti-adipogenic to a greater extent than BSP in 3T3-L1 preadipocytes.

Anti-Obesogenic Effects of Sulforaphane-Rich Broccoli (Brassica oleracea var. italica) Sprouts and Myrosinase-Rich Mustard (Sinapis alba L.) Seeds In Vitro and In Vivo.

Glucoraphanin (GRA), a glucosinolate particularly abundant in broccoli (Brassica oleracea var. italica) sprouts, can be converted to sulforaphane (SFN) by the enzyme myrosinase. Herein, we investigated the anti-obesogenic effects of broccoli sprout powder (BSP), mustard (Sinapis alba L.) seed powder (MSP), and sulforaphane-rich MSP-BSP mixture powder (MBP) in bisphenol A (BPA)-induced 3T3-L1 cells and obese C57BL/6J mice. In vitro experiments showed that MBP, BSP, and MSP have no cytotoxic effects. Moreover, MBP and BSP inhibited the lipid accumulation in BPA-induced 3T3-L1 cells. In BPA-induced obese mice, BSP and MBP treatment inhibited body weight gain and ameliorated dyslipidemia. Furthermore, our results showed that BSP and MBP could activate AMPK, which increases ACC phosphorylation, accompanied by the upregulation of lipolysis-associated proteins (UCP-1 and CPT-1) and downregulation of adipogenesis-related proteins (C/EBP-α, FAS, aP2, PPAR-γ, and SREBP-1c), both in vitro and in vivo. Interestingly, MBP exerted a greater anti-obesogenic effect than BSP. Taken together, these findings indicate that BSP and MBP could inhibit BPA-induced adipocyte differentiation and adipogenesis by increasing the expression of the proteins related to lipid metabolism and lipolysis, effectively treating BPA-induced obesity. Thus, BSP and MBP can be developed as effective anti-obesogenic drugs.

Codonopsis lanceolata and its active component Tangshenoside I ameliorate skeletal muscle atrophy via regulating the PI3K/Akt and SIRT1/PGC-1α pathways.

BACKGROUND: Skeletal muscle atrophy is caused by aging, disuse, malnutrition, and several diseases. However, there are still no effective drugs or treatments for muscle atrophy. Codonopsis lanceolata (CL), a traditional medicinal plant and food, has been reported to have anti-oxidative, anti-inflammatory, anti-tumor, and anti-obesity effects. PURPOSE: This study aimed to investigate the efficacy and active component of CL on muscle atrophy in vitro and to confirm the effect of CL and its active component on muscle atrophy and the underlying molecular mechanisms in vivo. STUDY: design/Methods This study used the dexamethasone (Dex)-induced muscle atrophy C2C12 myotube model and immobilization (IM)-induced muscle atrophy C57BL/6 mice model. In vitro study, the myotube diameter was measured. In vivo study, the grip strength, muscle mass (quadriceps, gastrocnemius, and soleus) and muscle fiber cross-sectional area (CSA) was measured. Western blot analysis and qRT-PCR were performed to confirm the underlying molecular mechanisms Results:In vitro study, CL and its main component, Tangshenoside I (TSI), effectively restored C2C12 myotube diameters decreased by Dex. Surprisingly, TSI was identified as the active component responsible for the overall efficacy of CL on muscle atrophy. In vivo study, CL and TSI, dose-dependently increased grip strength, mass muscle, and muscle fiber CSA reduced by IM. In the molecular mechanism studies, CL and TSI increased muscle protein synthesis via activating the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin complex 1 (mTORC1) pathway and decreased muscle protein degradation via inhibiting the muscle ring finger-1 (MuRF1) and muscle atrophy F-box protein (Atrogin-1) expressions. It also upregulated mitochondrial biogenesis via the silent information regulator 1 (SIRT1)/ peroxisome proliferator-activated receptor gamma and coactivator-1 alpha (PGC-1α) pathway. CONCLUSION: This study suggests that CL and its active component, TSI, can be potential drug candidates for the prevention and treatment of muscle atrophy.

The involvement of the noradrenergic system in the antinociceptive effect of cucurbitacin D on mice with paclitaxel-induced neuropathic pain.

Paclitaxel (sold under the brand name Taxol) is a chemotherapeutic drug that is widely used to treat cancer. However, it can also induce peripheral neuropathy, which limits its use. Although several drugs are used to attenuate neuropathy, no optimal treatment is available to date. In this study, the effect of cucurbitacins B and D on paclitaxel-induced neuropathic pain was assessed. Multiple paclitaxel injections (a cumulative dose of 8 mg/kg, i. p.) induced cold and mechanical allodynia from days 10 to 21 in mice, and the i. p. administration of 0.025 mg/kg of cucurbitacins B and D attenuated both allodynia types. However, as cucurbitacin B showed a more toxic effect on non-cancerous (RAW 264.7) cells, further experiments were conducted with cucurbitacin D. The cucurbitacin D dose-dependently (0.025, 0.1, and 0.5 mg/kg) attenuated both allodynia types. In the spinal cord, paclitaxel injection increased the gene expression of noradrenergic (α 1-and α 2-adrenergic) receptors but not serotonergic (5-HT1A and 3) receptors. Cucurbitacin D treatment significantly decreased the spinal α 1- but not α 2-adrenergic receptors, and the amount of spinal noradrenaline was also downregulated. However, the tyrosine hydroxylase expression measured via liquid chromatography in the locus coeruleus did not decrease significantly. Finally, cucurbitacin D treatment did not lower the anticancer effect of chemotherapeutic drugs when co-administered with paclitaxel in CT-26 cell-implanted mice. Altogether, these results suggest that cucurbitacin D could be considered a treatment option against paclitaxel-induced neuropathic pain.

Environmental obesogens (bisphenols, phthalates and parabens) and their impacts on adipogenic transcription factors in the absence of dexamethasone in 3T3-L1 cells.

Endocrine-disrupting chemicals (EDCs) are exogenous compounds that are capable of blocking or mimicking the action of bioidentical hormones. Obesogenic EDCs, commonly called obesogens, play an important role in adipogenesis. This study was carried out to determine the effects of select obesogens and their alternatives on adipogenesis in 3T3-L1 cells under dexamethasone (DEX)-free conditions. Preadipocytes were treated with a cocktail of 3-isobutyl-1-methylxanthine (IBMX) and insulin to which an obesogen (viz., bisphenol A (BPA) or its analogs BPS and BPF; dioctyl terephthalate; tris (2-ethylhexyl) trimellitate; or various parabens) had been added. A mixture containing IBMX, insulin, and DEX, which constitute the typical hormonal cocktail required for adipocyte differentiation, was used as the control against which the other groups were measured. The obesogens and the PBA analogs all had evident adipogenic effects under DEX-free conditions, as was determined by estimating the lipid accumulation levels in the cells using Oil Red O staining. Furthermore, the expression of adipogenic transcription factors (CCAAT/enhancer-binding protein-alpha, peroxisome proliferator-activated receptor-gamma, and adipocyte protein 2) was induced by 20 µM of BPA, BPS, or BPF at both the mRNA and protein levels, as determined through reverse transcription-polymerase chain reaction and western blot assays. Taken together, the results reveal that adipocyte differentiation can be induced by obesogens and their alternatives in the absence of DEX.

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.

Gamma-Aminobutyric Acid Increases Erythropoietin by Activation of Citrate Cycle and Stimulation of Hypoxia-Inducible Factors Expression in Rats.

Erythropoietin (EPO) is the primary regulator of erythropoiesis in the mammalian fetus and adult. Deficiency of EPO induces anemia. In this study, we investigated the effect of gamma-aminobutyric acid (GABA) on serum EPO levels and erythropoiesis in rats. Expression levels of Epo-related genes were measured by quantitative real-time PCR (qPCR) and expression of Epo and Epo receptor (Epor) proteins were measured by immunohistochemistry. The gene and protein expression profiles of kidney tissue in GABA-treated rats were evaluated by ribonucleic acid (RNA) sequencing and two-dimensional electrophoresis (2-DE), respectively. GABA significantly increased serum EPO levels and expression levels of Epo and Epor. GABA increased expression levels of hypoxia-inducible factor (Hif)-1 and Hif-2. Seven proteins with expression levels showing >2-fold change were identified by 2-DE followed by MALDI-TOF MS in GABA-treated rat kidney. The top KEGG pathway from the identified proteins was the tricarboxylic acid cycle, and nicotinamide adenine dinucleotide (NADH) dehydrogenase, succinate dehydrogenase, and isocitrate dehydrogenase were identified as key proteins. GABA treatment significantly increased ATP levels and NADH dehydrogenase activity in a dose-dependent manner. In conclusion, GABA shows a new physiological role in EPO production, and it can thus can contribute to the prevention of anemia when used alone or in combination with other anemia treating drugs.

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.

Hypouricemic Effect of Ethanol Extract of Aster glehni Leaves in Potassium Oxonate-Induced Hyperuricemic Rats.

The prevalence of gout is increasing worldwide, and control of serum uric acid level has been regarded as one of the therapeutic methods for gout. Inhibition of xanthine oxidase (XO) activity which can oxidize hypoxanthine to uric acid has been commonly proposed to decrease serum uric acid level. The aim of this study was to demonstrate the hypouricemic effect of ethanol extract of Aster glehni leaves (EAG) by in vitro and in vivo study in potassium oxonate (PO)-induced hyperuricemic rats. EAG possessed 132.5 ± 6.8 mg QE/g of total flavonoid and showed antioxidant activity. EAG showed in vitro and in vivo inhibitory activity against XO and significantly decreased serum uric acid level in PO-induced hyperuricemic rats without liver toxicity. These results show that EAG significantly attenuates hyperuricemia by inhibiting XO activity, which resulted in the decrease of serum uric acid level. Therefore, EAG might possess a potential therapeutic ability for improving gout.

Probiotic Potential of Enterococcus faecium Isolated from Chicken Cecum with Immunomodulating Activity and Promoting Longevity in Caenorhabditis elegans.

Probiotics, including Enterococcus faecium, confer a health benefit on the host. An Enterococcus strain was isolated from healthy chicken cecum, identified as E. faecium by 16S rDNA gene sequence analysis, and designated as E. faecium L11. To evaluate the potential of E. faecium L11 as a probiotic, the gastrointestinal tolerance, immunomodulatory activity, and lifespan extension properties of the strain were assayed. E. faecium L11 showed >66% and >62% survival in artificial gastric juice (0.3% pepsin, pH 2.5) and simulated small intestinal juice (0.5% bile salt and 0.1% pancreatin), respectively. Heat-killed E. faecium L11 significantly (p < 0.05) increased immune cell proliferation compared with controls, and stimulated the production of cytokines (IL-6 and TNF-α) by activated macrophages obtained from ICR mice. In addition, E. faecium L11 showed a protective effect against Salmonella Typhimurium infection in Caenorhabditis elegans. In addition, feeding E. faecium L11 significantly (p < 0.05) extended the lifespan of C. elegans compared with the control. Furthermore, genes related to aging and host defense were upregulated in E. faecium L11-fed worms. In conclusion, E. faecium L11, which prolongs the lifespan of C. elegans, may be a potent probiotic supplement for livestock.

Rhapontigenin converted from rhapontin purified from Rheum undulatum enhances the inhibition of melanin synthesis.

Rhapontigenin was produced from rhapontin isolated from a methanol extract of Rheum undulatum roots by enzymatic transformation. Rhapontin and rhapontigenin exhibited dose-dependent inhibition of tyrosinase activity and melanin synthesis in B16F10 melanoma cells, but the inhibitory activity of rhapontigenin was greater than that of rhapontin. Thus the bioconversion of rhapontin enhanced its ability to inhibit cellular tyrosinase activity and melanin synthesis.

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.