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At least 19 recordsLinked to original sources
PubMed2003

Syntheses of arbutin-alpha-glycosides and a comparison of their inhibitory effects with those of alpha-arbutin and arbutin on human tyrosinase.

The effects of 4-hydroxyphenyl alpha-glucopyranoside (alpha-arbutin) and 4-hydroxyphenyl beta-glucopyranoside (arbutin) on the activity of tyrosinase from human malignant melanoma cells were examined. The inhibitory effect of alpha-arbutin on human tyrosinase was stronger than that of arbutin. The K(i) value for alpha-arbutin was calculated to be 1/20 that for arbutin. We then synthesized arbutin-alpha-glycosides by the transglycosylation reaction of cyclomaltodextrin glucanotransferase using arbutin and starch, respectively, as acceptor and donor molecules. The structural analyses using 13C- and 1H-NMR proved that the transglycosylated products were 4-hydroxyphenyl beta-maltoside (beta-Ab-alpha-G1) and 4-hydroxyphenyl beta-maltotrioside (beta-Ab-alpha-G2). These arbutin-alpha-glycosides exhibited competitive type inhibition on human tyrosinase, and their K(i) values were calculated to be 0.7 mM and 0.9 mM, respectively. These arbutin-alpha-glycosides possessed stronger inhibitory activity than arbutin, but less activity than alpha-arbutin. These results suggested that the alpha-glucosidic linkage of hydroquinone-glycosides plays an important role in the inhibitory effect on human tyrosinase.

Arbutin↗
PubMed1999

Lipid composition determines the effects of arbutin on the stability of membranes.

Arbutin (hydroquinone-beta-D-glucopyranoside) is an abundant solute in the leaves of many freezing- or desiccation-tolerant plants. Its physiological role in plants, however, is not known. Here we show that arbutin protects isolated spinach (Spinacia oleracea L.) thylakoid membranes from freeze-thaw damage. During freezing of liposomes, the presence of only 20 mM arbutin led to complete leakage of a soluble marker from egg PC (EPC) liposomes. When the nonbilayer-forming chloroplast lipid monogalactosyldiacylglycerol (MGDG) was included in the membranes, this leakage was prevented. Inclusion of more than 15% MGDG into the membranes led to a strong destabilization of liposomes during freezing. Under these conditions arbutin became a cryoprotectant, as only 5 mM arbutin reduced leakage from 75% to 20%. The nonbilayer lipid egg phosphatidylethanolamine (EPE) had an effect similar to that of MGDG, but was much less effective, even at concentrations up to 80% in EPC membranes. Arbutin-induced leakage during freezing was accompanied by massive bilayer fusion in EPC and EPC/EPE membranes. Twenty percent MGDG in EPC bilayers completely inhibited the fusogenic effect of arbutin. The membrane surface probes merocyanine 540 and 2-(6-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl)amino)hexanoyl-1-hexadecanoyl-sn-glycero-3-phosph ocholi ne (NBD-C(6)-HPC) revealed that arbutin reduced the ability of both probes to partition into the membranes. Steady-state anisotropy measurements with probes that localize at different positions in the membranes showed that headgroup mobility was increased in the presence of arbutin, whereas the mobility of the fatty acyl chains close to the glycerol backbone was reduced. This reduction, however, was not seen in membranes containing 20% MGDG. The effect of arbutin on lipid order was limited to the interfacial region of the membranes and was not evident in the hydrophobic core region. From these data we were able to derive a physical model of the perturbing or nonperturbing interactions of arbutin with lipid bilayers.

4-Chloro-7-nitrobenzofurazan↗
PubMed1996

Arbutin inhibits PLA2 in partially hydrated model systems.

Arbutin is a glycosylated hydroquinone found at high concentrations in certain plants capable of surviving extreme and sustained dehydration. In this paper, we examine a potential role of this molecule in anhydrobiosis. We have studied its effects on the physical properties of phospholipids and on preservation of liposomes during drying. Arbutin depresses the gel to liquid crystalline phase transition temperature of dry phospholipids, as measured by differential scanning calorimetry, with a pattern similar to that seen in phospholipids dried with the disaccharide trehalose. Unlike trehalose, however, arbutin does not protect dry liposomes from leaking their contents. Also, using Fourier transform infrared spectroscopy, we found an increase in the vibrational frequency of the phosphate asymmetric stretch in partially hydrated phospholipids in the presence of arbutin. Trehalose, by contrast, depresses the frequency of the phosphate in dry phospholipids, indicating that the modes of interaction of trehalose and arbutin with the bilayer are different. Previously, we have shown that phospholipases can be active in liposomes with surprisingly low water contents. Based on the structural similarity of arbutin to a known inhibitor of phospholipase A2 (PLA2), it appeared possible that arbutin might serve as an inhibitor of phospholipases. Liposomes of varying composition were lyophilized in the presence and absence of phospholipases. When the liposomes were partially rehydrated at 76% relative humidity, arbutin inhibited PLA2, but did not inhibit phospholipases B or C. Accumulation of enzyme product in the liposome membranes was measured by analytical thin layer chromatography, and was taken as a measure of enzyme activity. Arbutin did not inhibit any of the enzymes in the presence of excess water. Based on these data, hypotheses are presented concerning the mechanism of PLA2 inhibition by arbutin in the mostly dehydrated state.

Arbutin↗
PubMed2006

Mutagenicity of arbutin in mammalian cells after activation by human intestinal bacteria.

Arbutin (hydroquinone-beta-D-glucopyranoside) is present in various food plants. Its aglycone, hydroquinone, is mutagenic and carcinogenic. We investigated whether hydroquinone may be released under conditions encountered in the human gastrointestinal tract. Arbutin was stable in artificial gastric juice. Fecal slurries from nine human subjects completely converted arbutin (2 mM) into hydroquinone. Four of nine representative human intestinal species investigated, namely Eubacterium ramulus, Enterococcus casseliflavus, Bacteroides distasonis, and Bifidobacterium adolescentis, deglycosylated arbutin at rates of 21.08, 16.62, 8.43 and 3.59 nmol x min(-1) x (mg protein)(-1), respectively. In contrast, homogenates from small intestinal mucosa and cytosolic fractions from colon mucosa deglycosylated arbutin at substantially lower rates: 0.50 and 0.09 nmol x min(-1) x (mg protein)(-1), respectively. Arbutin, unlike hydroquinone, did not induce gene mutations in Chinese hamster V79 cells in the absence of an activating system. However, in the presence of cytosolic fractions from E. ramulus or B. distasonis, arbutin was strongly mutagenic. Cytosolic fraction from Escherichia coli, showing no arbutin glycosidase activity, was not able to activate arbutin in this model system. The release of the proximate mutagen hydroquinone from arbutin by intestinal bacteria in the immediate vicinity of the colon mucosa may pose a potential risk.

Adult↗
PubMed1998

Interactions of arbutin with dry and hydrated bilayers.

The glycosylated hydroquinone arbutin (4-hydroxyphenyl-beta-D-glucopyranoside) is abundant in certain resurrection plants, which can survive almost complete dehydration for prolonged periods. Little is known about the role of arbutin in vivo, but it is thought to contribute toward survival of the plants in the dry state. We have investigated the interactions of arbutin with model membranes under conditions of high and low hydration, as well as the possible participation of arbutin in carbohydrate glasses formed at low water contents. Retention of a trapped soluble marker inside large unilamellar vesicles and fusion of vesicles was monitored by fluorescence spectroscopy. Effects of arbutin on glass-transition temperatures and hydrated membrane phase-transition temperatures were measured by differential scanning calorimetry. The possible insertion of arbutin into membrane bilayers was estimated by following arbutin auto-fluorescence. Evidence is presented that arbutin does not change the glass-transition temperature of a sucrose/trehalose glass, but that arbutin does interact with hydrated membranes by insertion of the phenol moiety into the lipid bilayer. This interaction causes increased membrane leakage during air-drying by a mechanism other than vesicle-vesicle fusion. Implications of these effects on the dehydrated plant cells, as well as possible methods of obviating the damage, are discussed.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2001

The effect of arbutin on membrane integrity during drying is mediated by stabilization of the lamellar phase in the presence of nonbilayer-forming lipids.

Arbutin (4-hydroxyphenyl-beta-glucopyranoside) is a solute accumulated to high concentrations in drought and frost resistant plants. Arbutin can inhibit membrane lysis, both free radical-mediated and enzymatic in nature, and it has been suggested that arbutin might contribute to membrane stabilization in these plants. However, we found that arbutin destabilized phosphatidylcholine vesicles during drying and rehydration, which appears to be inconsistent with the proposed protective function of arbutin for membranes. We also found, however, that arbutin stabilizes membranes containing nonbilayer-forming lipids during freezing. We now report that, in liposomes containing the nonbilayer-forming lipids monogalactosyldiacylglycerol (MGDG) or phosphatidylethanolamine (PE), arbutin served a protective function during drying, as measured by retention of carboxyfluorescein (CF) and extent of vesicle fusion. In hydrated samples containing these lipids, arbutin stabilized the lamellar liquid crystalline phase. Therefore, the interaction between arbutin and lipid membranes and the resulting effects on membrane stability depend, in a complex manner, on the lipid composition of the membrane.

Arbutin↗
PubMed1991

[Inhibitory effect of arbutin on melanogenesis--biochemical study using cultured B16 melanoma cells].

Inhibitory effect of arbutin (hydroquinone-beta-D-glucopyranoside) on the melanogenesis was studied biochemically using cultured B16 melanoma cells. The maximum arbutin concentration lacking an inhibitory effect on cell growth was 5 X 10(-5) M. At this concentration, melanin content per cell was decreased significantly to about 39%, compared with that of arbutin untreated cells. Also, tyrosinase activity of arbutin treated cells was decreased significantly. When arbutin was added to B16 melanoma cell suspension, arbutin was not hydrolyzed to liberate hydroquinone. Further, tyrosinase activity in crude preparations from B16 melanoma cells was inhibited by arbutin. From these results, it is suggested that arbutin can inhibit the melanogenesis by affecting not only the synthesis but also the activity of tyrosinase rather than by killing melanocytes B16 melanoma cells. Also, it is suggested that hydroquinone is not responsible for the inhibitory effect of arbutin on the melanogenesis.

Animals↗
PubMed1998

Arbutin increases the pigmentation of cultured human melanocytes through mechanisms other than the induction of tyrosinase activity.

We assessed the effects of arbutin on the pigmentation of cultured normal human melanocytes. As indicated by a cell-blotting assay, arbutin at concentrations in the range of 0.5-8 mM increased the pigmentation of the cultured melanocytes, while kojic acid at concentrations in the range of 0.5-4 mM decreased the pigmentation. The pigmentation-augmenting effect of arbutin was further confirmed by the results of a cell-pelleting assay, the traditional method of assessment. Treatment of the cells with arbutin increased the melanin content of the cells and the protein content as well. On the other hand, the tyrosinase activity in the cells was reduced by arbutin treatment. The levels of transcription of tyrosinase and tyrosinase related protein-1 genes were not affected by arbutin treatment as indicated by a semi-quantitative reverse transcription-polymerase chain reaction assay. These results demonstrate that arbutin promotes an increase in pigmentation of cultured human melanocytes that is not mediated by augmented tyrosinase activity.

Arbutin↗
PubMed1995

Effects of alpha- and beta-arbutin on activity of tyrosinases from mushroom and mouse melanoma.

The effects of alpha- and beta-arbutin on the activity of tyrosinases from mushroom and mouse melanoma were examined. alpha-Arbutin was synthesized from hydroquinone and starch using glucoside synthetase (GSase). beta-Arbutin inhibited both tyrosinase activities from mushroom and mouse melanoma. alpha-Arbutin inhibited only the tyrosinase from mouse melanoma, 10 times as strongly as beta-arbutin. The IC50 of alpha-arbutin was 0.48 mM and its inhibitory mechanism was speculated to be mixed type inhibition, while that of beta-arbutin was noncompetitive.

Animals↗
PubMed2004

[The effects of aloesin and arbutin on cultured melanocytes in a synergetic method].

OBJECTIVE: To study the effects of aloesin and arbutin on normal cultured human melanocytes in synergetic method. METHODS: Building up the system of cultured human melanocytes. The cultured melanocytes in vitro were treated with the mixture of aloesin and arbutin. The cell viability and tyrosinase activity was measured by MTT assay, utilization of L-Dopa as the substrate respectively; melanin content was measured by image analysis system. Furthermore, the effects of the mixture on melanocytes were compared with that of aloesin and arbutin. RESULTS: The mixture of aloesin and arbutin showed an inhibition on tyrosinase activity of human melanocytes and reduced significantly melanin content. Between the mixture and the single use of aloesin or arbutin, there is significant difference (P < 0.05). On the other hand, the mixture has little influence on melanocytes viability and there is negative significance. CONCLUSION: The mixture of aloesin and arbutin can significantly inhibit the tyrosinase activity and melanogenesis of cultured human melanocytes. It showed the effects of aloesin and arbutin in a synergistic manner. It is worth to give farther study later.

Arbutin↗
PubMed2006

Enzymatic synthesis of arbutin undecylenic acid ester and its inhibitory effect on mushroom tyrosinase.

A novel tyrosinase inhibitor, an arbutin derivative having undecylenic acid at the 6-position of its glucose moiety, was enzymatically synthesized. Its inhibitory activity was studied in vitro by using catechol and phenol as substrates. The IC(50) value of the arbutin ester on tyrosinase using catechol (4 x 10(-4) M) was 1% of that when arbutin (4 x 10(-2) M) was used. Using phenol, IC(50) of the arbutin ester (3 x 10(-4) M) as substrate was 10% of that of arbutin (3 x 10(-3) M). These results suggest that the arbutin ester inhibits the latter part of the tyrosinase reaction, which consists of hydroxylation and oxidation.

Agaricales↗
PubMed2005

Analyses of arbutin and chlorogenic acid, the major phenolic constituents in Oriental pear.

The HPLC retention time, photodiode array UV spectrum analysis, and LC/MS results indicated that arbutin and chlorogenic acid are the main phenolic constituents in Oriental pear. The two compounds exist in different organs of the Yali pear, which is one of the major cultivars of Pyrus bretschnrideri. The contents of arbutin in the leaf bud, floral bud, flower, and young fruit were 11.9, 12.4, 8.29, and 9.92 mg/g fresh weight (FW), respectively. Chlorogenic acid amounts in the same organs were 2.26, 3.22, 5.32, and 3.72 mg/g FW, respectively. During development, the concentration of the two compounds in Yali pears was the greatest in young fruit (9.92 mg/g FW of arbutin and 3.72 mg/g FW of chlorogenic acid), and then declined swiftly with fruit growth to less than 0.400 and 0.226 mg/g FW, respectively, in mature fruit. Large differences existed in the distribution of the two compounds in parts of the mature fruit of 14 Oriental pear cultivars. The greatest concentration of arbutin was found in the peel (1.20 mg/g FW), which was 3-5 times greater than that found in the core and 10-45 times greater than the level in the pulp. The concentration of chlorogenic acid in the core was greater than that in the peel. The compounds in 17 cultivars of Oriental pear, including P. bretschnrideri, Pyrus pyrifolia, Pyrus ussuriensis, and Pyrus sinkiangensis, were compared with those in 5 cultivars of Occidental pear (Pyrus communis). The mean concentration of arbutin in the Oriental pear cultivars was 0.164 mg/g FW, greater than the 0.083 mg/g FW found in the Occidental pear cultivars. The greatest arbutin content was 0.400 mg/g FW, found in the Yali pear. However, the mean concentration of chlorogenic acid in the Oriental pear was 0.163 mg/g FW, less than that found in the Occidental pear (0.309 mg/g FW).

Arbutin↗
PubMed2005

Urinary excretion of arbutin metabolites after oral administration of bearberry leaf extracts.

An HPLC assay with fluorimetric detection of the arbutin metabolites hydroquinone glucuronide (2) and hydroquinone sulphate (6) in urine was developed and validated. Methylarbutin (4) and 6 were synthesised as reference substances. Compound 2 was prepared enzymatically from hydroquinone and uridine 5'-diphosphoglucuronic acid using the glucosyltransferase system of rat liver microsomes and enriched by two liquid-liquid and an additional solid phase extraction. Compound 2 as the main component of this purified product was identified by UV and fluorescence spectroscopy, by HPLC-MS, and by enzymatic hydrolysis to hydroquinone (5). The assay yields precise and accurate urine levels of 2, 5 and 6 in the concentration range expected after oral administration of recommended therapeutic doses of bearberry leaf extract. In a preliminary pharmacokinetic study on 3 volunteers the time-dependent renal excretion of arbutin metabolites 2, 5 and 6 was investigated after ingestion of an aqueous bearberry leaf extract containing an arbutin dose recommended by the German Kommission E. More than half of the administered dose of arbutin was excreted within 4 hours mainly in form of the metabolites 2 and 6 and more than 75 % of the total applied arbutin was excreted within 24 h. The elimination of 5 was negligible in 2 out of 3 volunteers. The excretion of this metabolite in the third test person reached 5.6 % of the total administered arbutin dose. The preliminary pharmacokinetic results confirm that renal elimination of toxicologically critical concentrations of the metabolite 5 will not be expected.

Administration, Oral↗
PubMed1990

[Pharmacological study on Arctostaphylos uva-ursi (L.) Spreng. II. Combined effects of arbutin and prednisolone or dexamethazone on immuno-inflammation].

A study was carried out to examine the combined effect of arbutin isolated from the leaves of Arctostaphylos uva-ursi (L.) Spreng. (Bearberry leaf) and prednisolone or dexamethazone on Type IV allergic reaction-induced immuno-inflammation. Contact dermatitis caused by picryl chloride (PC-CD) and sheep red cell delayed type hypersensitivity (SRBC-DTH) in mice was not inhibited by the oral application of arbutin at 2 divided doses immediately before and 16 h after the application, but arbutin at doses of 10, 50 mg/kg 24 h after the application speedily decreased the swelling of PC-CD and SRBC-DTH. Arbutin plus prednisolone or dexamethazone showed the inhibitory effect on the swelling of PC-CD and SRBC-DTH stronger than that of prednisolone or dexamethazone alone. Prednisolone and dexamethazone decreased the weight of thymus and spleen in intact, PC-CD and SRBC-DTH mice, but arbutin did not show these effects. These results suggest that arbutin may increase the inhibitory action of prednisolone and dexamethazone on PC-CD and SRBC-DTH, but further investigations are required to understand the mechanism involved.

Animals↗
PubMedDate not supplied

[Pharmacological studies on leaf of Arctostaphylos uva-ursi (L.) Spreng. III. Combined effect of arbutin and indomethacin on immuno-inflammation].

A study was carried out to examine the combined effect of arbutin isolated from the leaves of Arctostaphylos uva-ursi (L.) Spreng. (Bearberry leaf) and indomethacin on Type IV allergic reaction-induced immuno-inflammation, carrageenin-induced edema and adjuvant-induced arthritis. Contact dermatitis caused by picryl chloride (PC-CD) and sheep red cell delayed type hypersensitivity (SRBC-DTH) was not inhibited by the oral application of arbutin at 2 divided doses immediately before and 16 h after the application, but arbutin at dose of 50 mg/kg 24 h after the application rapidly decreased the swelling of PC-CD. Arbutin (p.o.) plus indomethacin (s.c.) showed inhibitory effect on the swelling of PC-CD and SRBC-DTH stronger than that of indomethacin alone. When arbutin (p.o.) and indomethacin (s.c.) in a given portion were simultaneously administered, the inhibitory effect was more potent than that of indomethacin alone in both carrageenin-induced edema and adjuvant-induced arthritis. These results suggest that arbutin may increase the inhibitory action of indomethacin on PC-CD, SRBC-DTH, carrageenin-induced edema and adjuvant-induced arthritis, but further investigations are required to understand the mechanism involved.

Animals↗
PubMed1996

Arbutin: mechanism of its depigmenting action in human melanocyte culture.

Arbutin, a naturally occurring beta-D-glucopyranoside of hydroquinone, is effective in the topical treatment of various cutaneous hyperpigmentations characterized by hyperactive melanocyte function. We examined the mechanism of its depigmenting action in human melanocyte cultures. Arbutin inhibited the tyrosinase activity of cultured human melanocytes at noncytotoxic concentrations. It did not affect the expression of tyrosinase mRNA. Melanin production was inhibited significantly by arbutin, as determined by measuring eumelanin radicals with an electron spin resonance spectrometer. The study of the kinetics and mechanism for inhibition of tyrosinase confirms the reversibility of arbutin as a competitive inhibitor of this enzyme. The utilization of L-tyrosine or L-dopa as the substrate suggests a mechanism involving competition with arbutin for the L-tyrosine binding site at the active site of tyrosinase. These results suggest that the depigmenting mechanism of arbutin in humans involves inhibition of melanosomal tyrosinase activity, rather than suppression of the expression and synthesis of tyrosinase.

Arbutin↗
PubMed1999

Aloesin and arbutin inhibit tyrosinase activity in a synergistic manner via a different action mechanism.

In this study, we present evidence that cotreatment of aloesin and arbutin inhibits tyrosinase activity in a synergistic manner by acting through a different action mechanism. Aloesin or arbutin similarly inhibited enzyme activity of human- and mushroom-tyrosinases with an IC50 value of 0.1 or 0.04 mM, respectively. Lineweaver-Burk plots of the enzyme kinetics data showed that aloesin inhibited tyrosinase activity noncompetitively with a Ki value of 5.3 mM, whereas arbutin did it competitively (Maeda, 1996). We then examined whether cotreatment of these agents inhibits the tyrosinase activity in a synergistic manner. The results showed that 0.01 mM aloesin in the presence of 0.03 mM arbutin inhibited activity of mushroom by 80% of the control value and the reverse was also true. The inhibitory effects were calculated to be synergistic according to the Bürgi method. Taken together, we suggest that aloesin along with arbutin inhibits in synergy melanin production by combined mechanisms of noncompetitive and competitive inhibitions of tyrosinase activity.

Agaricales↗
PubMed2006

FTIR analysis of the interaction of arbutin with dimyristoyl phosphatidylcholine in anhydrous and hydrated states.

In this paper, the interaction of arbutin with dimyristoylphosphatidylcholine bilayers was studied by FTIR spectrometry. The results show that arbutin interacts in different extents with the phosphate and carbonyl groups of membranes in the gel state, the liquid crystalline state or subjected to osmotic stress. The effect, in the presence of water, on the antisymmetric stretching of the phosphate groups is qualitatively similar to that found with other molecules composed by a glucose moiety such as trehalose and sucrose. However, significant differences were found between these compounds and arbutin in the carbonyl region. Arbutin displaces the PO2- antisymmetric stretching to lower frequencies in lipids dispersed in water. This indicates strong hydrogen bonding. In contrast, in the solid state, this frequency increases. The effect on the carbonyl groups varies depending on the hydration state of the bilayer, which is achieved by changing the phase state of the bilayer or by osmotic stress. The hydrocarbon region is not affected by arbutin in the excess of water. However, symmetric and antisymmetric stretching of CH2 and CH3 are strongly affected in the dry state.

Arbutin↗