PHYTOTHERAPY RESEARCH Phytother. Res. (2014) Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/ptr.5161

The Effects of Galangin on a Mouse Model of Vitiligo Induced by Hydroquinone Shi-Xia Huo,1 Xin-Ming Liu,1,2 Chun-Hui Ge,1 Li Gao,1 Xiao-Ming Peng,1 Ping-Ping Zhao1 and Ming Yan1* 1

Department of Cell and Molecular Laboratory Xinjiang Institute of Traditional Uighur Medicine, Xinjiang Laboratory of Uighur Medical Prescription, Urumqi, Xinjiang 830049, China 2 Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Beijing 100193, China

Galangin, the main active component of Alpinia officinarum Hance, was tested in a mouse model of vitiligo induced in C57BL/6 mice by the topical application of 2 mL of 2.5% hydroquinone daily to shaved areas (2 × 2 cm) of dorsal skin for 60 days. Thirty days after the final application of hydroquinone, galangin (0.425, and 4.25 mg/kg) was administered orally for 30 days. The hair colour darkened when it grew back after treatment, and histological analysis showed that the number of melanin-containing hair follicles had increased after treatment with all doses of galangin groups and 8-methoxypsoralen (8-MOP, the positive control) compared with the untreated vitiligo group (p < 0.05). The number of skin basal layer melanocytes and melanin-containing epidermal cells had also increased significantly with the application of 4.25 mg/kg of galangin. The concentration of tyrosinase (TYR) in serum was found to have increased, whereas the content of malondialdehyde and the activity of cholinesterase had decreased after treatment with all doses of galangin and 8-MOP, compared with control (p < 0.05). The expression of TYR protein in treated areas of skin also increased with the application of 4.25 mg/kg galangin and 8-MOP. In conclusion, the results showed that galangin was able to improve vitiligo induced by hydroquinone in mice, with the activity related to concentrations of TYR, expression of TYR protein, activity of malondialdehyde and content of cholinesterase. Galangin may therefore be a potential candidate for the treatment of vitiligo, subject to further investigation. Copyright © 2014 John Wiley & Sons, Ltd. Keywords: galangin; vitiligo; mouse; hydroquinone; melanin; melanocytes; cholinesterase; tyrosinase; malondialdehyde.

INTRODUCTION Vitiligo is a cutaneous disorder of depigmentation, characterized by progressive loss of melanocytes. It occurs worldwide and can affect up to 2% of the population, especially younger people. It commonly presents on the centre of the face and the genitals, or localized to the hands and feet, and less commonly on the trunk and proximal extremities (Taieb and Picardo, 2009). Patients with vitiligo often suffer psychoemotional stress and social isolation, although there may be no other physical problems. Sixty-six percent of vitiligo patients have reported feeling embarrassed about their appearance: more than half of patients felt uncomfortable socializing, leading to severe depression in some patients, even to suicide (Porter et al., 1987). Although several treatment options aimed at restoring pigmentation are available, and include excimer laser and surgical treatment as well as steroid therapy (Boissy and Lamoreux, 1988; Manga and Orlow, 2012), they are not used widely because they are not successful for all patients and have side effects, which some find unacceptable. Excimer laser and surgery are painful and expensive, and prolonged steroid use leads to decreased immunity (Falabella, 2000). Therefore, alternative methods are needed.

* Correspondence to: Ming Yan, Department of Cell and Molecular Laboratory Xinjiang Institute of Traditional Uighur Medicine, Xinjiang Laboratory of Uighur Medical Prescription, Urumqi, Xinjiang, 830049, China. E-mail: [email protected]

Copyright © 2014 John Wiley & Sons, Ltd.

Alpinia officinarum Hance has been used traditionally to treat symptoms of vitiligo in Uighur medicine in China (Tuerxun, 1999). Galangin (Fig. 1) is one of the main active constituents of A. officinarum. It has been reported that galangin has antioxidative (Russo et al., 2002), free radical scavenging and anticancer activities (Heo et al., 2001), but to our knowledge, no investigations have been carried out to support its folklore use in vitiligo. This study focuses on the effects of galangin in a mouse model of vitiligo induced by hydroquinone and its potential mechanisms.

MATERIALS AND METHODS Chemicals and reagents. Galangin was purchased from the National Institute for The Control of Pharmaceutical and Biological Products in China. 8-Methoxypsoralen (8-MOP) was purchased from Tokyo Kasei Kogyo Co., Ltd.

Animals and treatment. Male C57BL/6 mice weighing 20 ± 2 g and aged 5–6 weeks were obtained from Beijing Vital River Laboratory Animal Technology Co., Ltd. Animals were kept under 24 ± 1 °C and 60% humidity, with food and water available ad libitum. Briefly, 60 male mice were randomly divided into six groups of ten animals and treated as follows: (a) untreated control vehicle group, treated with distilled water and sodium Received 3 April 2014 Accepted 10 April 2014

S.-X. HUO ET AL.

(Olympus Optical Co, Ltd, Tokyo, Japan), and melanincontaining epidermal cells were counted. This was repeated ten high magnification fields and calculated mean of cells. Figure 1. The chemical structure of galangin.

carboxymethyl cellulose (CMC-Na, 0.5%); (b) control vitiligo model group, treated with hydroquinone (2.5%) and CMC-Na (0.5%); (c) vitiligo positive treatment control, 8-MOP, group, treated with hydroquinone (2.5%) and 8-MOP (4.25 mg/kg); and (d, e) galangintreated vitiligo groups, 0.425 and 4.25 mg/kg, respectively, with the hydroquinone (2.5%) treatment. Hairs were shaved from the dorsal skin of each mouse over an area of 2 × 2 cm. The shaved skin of vehicle control group (a) was smeared with distilled water for 60 days with administration of CMC-Na (0.5%) orally after 30 days; all other groups (b–e) were smeared with by hydroquinone (2.5%) for 60 days, with administration of CMC-Na (0.5%), and either 8-MOP or galangin orally for 30 days, starting at day 31. Hydroquinone (2.5%) was dissolved in distilled water. Mice were sacrificed 2 h after the final administration, and blood and skin tissue were harvested. All animal handling procedures received approval from the Animal Management Ordinance of the Chinese Ministry of Health and the animal experiment standards approved by the Animal management committee of Laboratory Animal Center of Xinjiang. Measurement of melanin-containing hair follicles. The melanin-containing hair follicles in the treat areas of skin of mice were observed by histological analysis (Takeuchi et al., 2004). A portion of the skin was cut and fixed with 10% neutral-buffered formalin, followed by paraffin embedding. Hematoxylin-eosin staining was performed on sections of approximately 5-mm thickness. Fifty hair follicles were observed under the light microscope (×100) (Olympus Optical Co, Ltd, Tokyo, Japan), and melanin-containing hair follicles were counted. Measurement of basal melanocytes. Basal melanocytes in the shaved areas of skin were observed by histological analysis (Birbeck et al., 1961). A portion of the skin was cut and fixed with 10% neutral-buffered formalin, followed by paraffin embedding. Dopa-oxidase staining was performed on sections of approximately 5-mm thickness, and basal melanocytes were stained brown. One hundred cells were observed at high magnification (×400) (Olympus Optical Co, Ltd, Tokyo, Japan), and basal melanocytes were counted. The counts were repeated for ten high magnification fields and the mean cell number calculated. Measurement of melanin-containing epidermal cells. Melanin-containing epidermal cells in the shaved areas of skin were observed by histological analysis (Birbeck et al., 1961). A portion of the skin was cut and fixed with 10% neutral-buffered formalin, followed by paraffin embedding. Lillie staining was performed on sections of approximately 5-mm thickness. The melanin-containing epidermal cells showed dark green. One hundred cells were observed under high magnification (×400) Copyright © 2014 John Wiley & Sons, Ltd.

Concentration of tyrosinase in serum. Tyrosinase (TYR) activity was measured spectrophotometrically. Briefly, the TYR assay was performed in 96-well plates as described by Matsuda et al. (1996), with some modifications. To 30 μL of serum, 10 μL of L-DOPA cofactor 0.25 mM in sodium phosphate buffer (1 M, pH 7.2) was added, and the reaction incubated at 37 °C for 60 min. The reaction was stopped by cooling, and the yield of dopachrome determined spectrophotometrically at 492 nm (BIO-RAD550, Bio-Rad, USA). A linear equation of concentration of TYR and absorbance values was established, y = 0.0207x + 0.1082, r = 0.99518 (Seymour, 1963), and used to calculate the effects of the test samples on the enzyme. Estimation of tyrosinase protein in skin of mice. The expression of TYR protein in the shaved areas of skin was detected by immunohistochemistry (Vries et al., 1998 ). TYR antibody (Santa Cruz, USA) was the first antibody, strept avidin–biotin complex (SABC, Hebei Bio-high technology, China) the second antibody, polysine (Sigma, USA) the coating agent and diaminobenzidine (DAB, Hebei Bio-high technology, China) the reagent. Positive cells were counted in five fields by an image analysis system (Image-Pro Plus v 5.1, Media Cybernetics USA) and were observed at high magnification (×400) (Olympus Optical Co, Ltd, Tokyo, Japan). The number of positive cells was calculated as a percentage.

Estimation of cholinesterase activity and content of malondialdehyde in serum. The CHE activity and MDA content in serum were assayed by kit, according to the manufacturers’ assay kit (Nanjing Jiancheng Bioengineering Co Ltd, China ), used according to the manufacturer’s protocols, and detected by Microplate reader at 520 and 532 nm (BIO-RAD550, Bio-Rad, USA).

Statistical analysis. Results were expressed as the mean ± SD for the number (n) of mice in each experimental group. The overall significance of the results was determined by one-way analysis of variance using the SPSS version 16.0 statistical software package. Probability values (p) less than 0.05 were considered statistically significant.

RESULTS Colour of hair regrowth While the hair colour of mice in all treatments groups turned darker than that of the model group (Fig. 2), it was much greater in the 8-MOP group (the positive control) and in the lower dose (0.425 mg/kg) galangin group. Phytother. Res. (2014)

EFFECTS OF GALANGIN ON MICE VITILIGO MODEL

Effects of galangin on melanin-containing hair follicles, basal melanocytes and epidermal cells Histological analysis showed the effects of galangin on the numbers of melanin-containing follicles, the basal melanocytes and melanin-containing epidermal cells in the shaved skin areas of mice with hydroquinone-induced vitiligo (Table 1). The control vitiligo group (treated with hydroquinone only) showed a significant decrease in melanin-containing follicles, basal melanocytes and melanin-containing epidermal cells compared with the untreated control group. The number of melanincontaining hair follicles in the treated areas was found to be increased at all dosages of galangin and 8-MOP group (p < 0.01, compared with the untreated vitiligo model group), while mice administered 4.25 mg/kg galangin, the cells of basal melanocyte and melanin-containing epidermal cell were increased significantly compared with the model group (p < 0.05; p < 0.01). Effect of galangin on the concentration of tyrosinase and tyrosinase protein expression Figure 3 shows the effects of galangin on the concentration of TYR in the serum of mice with hydroquinone -induced

vitiligo. The concentration of TYR in the group treated with hydroquinone only (vitiligo control group) was significantly lower than that of the untreated control group ( p < 0.01). All three doses of galangin and 8-MOP produced higher concentrations of TYR than that of model group ( p < 0.05). Figure 4 shows the effects of galangin on TYR protein expression in hydroquinone-induced vitiligo. Hydroquinone produced a significant decrease in expression of TYR protein compared with the control group (p < 0.01). Galangin at 4.25 mg/kg dose and 8-MOP elicited an increase in expression of TYR protein significantly, compared with model group (p < 0.01).

Effects of galangin on cholinesterase activity and content of malondialdehyde in serum Table 2 shows that treatment with hydroquinone alone induced a significant increase in the content of MDA and activity of CHE in serum, compared with the untreated control group (p < 0.01). Galangin and 8-MOP produced a significant decrease at all dosages significantly ( p < 0.01), compared with the vitiligo control group.

Figure 2. Hair colour of each group after treatment. (a) Control group; (b) model vitiligo group; (c) 8-MOP group; (d) galangin 0.425 mg/kg; (e) galangin 4.25 mg/kg; Control group (a) was smeared with distilled water for 60 days, administration of sodium carboxymethyl cellulose (0.5%) orally for 30 days; Others (b–e) were smeared with hydroquinone (2.5%) for 60 days, administration of 0.5%CMC-Na, 8-MOP and galangin orally for 30 days, starting at 31st day. This figure is available in colour online at wileyonlinelibrary.com/journal/ptr.

Table 1. Effects of galangin on melanin-containing follicles, basal melanocytes and melanin-containing epidermal cells in dorsal skin of mice (x ± SD, n = 10) Experimental group Control(a) Model(b) 8-MOP(c) Galangin(d) Galangin(e)

Dosage(mg/kg)

Melanin-containing hair follicles

Basal melanocytes

Melanin-containing epidermal cells

/ / 4.25 0.425 4.25

29.00 ± 1.73 17.50 ± 1.41ΔΔ 35.60 ± 2.30** 43.20 ± 2.17** 34.86 ± 1.21**

21.88 ± 2.90 8.40 ± 1.14ΔΔ 9.60 ± 1.14 9.40 ± 1.34 10.86 ± 1.07**

21.25 ± 1.83 10.60 ± 2.19ΔΔ 11.40 ± 1.52 11.80 ± 1.30 15.14 ± 2.61*

8-MOP, 8-methoxypsoralen. ΔΔp < 0.01 versus the control. *p < 0.05 versus the model. **p < 0.01 versus the model. Copyright © 2014 John Wiley & Sons, Ltd.

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Figure 3. Effects of galangin on TYR concentration in serum of mice. Doses as in Fig. 2, that is, (d) galangin 0.425 mg/kg and (e) Galangin 4.25 mg/kg. Data are presented as mean ± SD, n = 10. ΔΔ p < 0.01 versus untreated control group; **p < 0.01 and *p < 0.05 versus model group.

Figure 4. Effects of galangin on tyrosinase protein expression in treated areas of skin of mice. Data are presented as mean ± SD, n = 10. p < 0.01 versus untreated control group; **p < 0.01 and versus vitiligo model group.

Table 2. Effects of galangin on cholinesterase and malondialdehyde in serum of mice (x ± SD, n = 10) Experimental group Control(a) Model(b) 8-MOP(c) Galangin(d) Galangin(e)

Dosage (mg/kg)

MDA (nmol/mL)

CHE (U/mL)

/ / 4.25 0.425 4.25

10.48 ± 0.84 18.22 ± 1.40ΔΔ 15.38 ± 1.74** 15.33 ± 1.29** 15.56 ± 1.37**

55.81 ± 5.97 80.76 ± 6.70ΔΔ 71.34 ± 1.26* 68.09 ± 4.36** 70.64 ± 4.88**

CHE, cholinesterase; MDA, malondialdehyde. ΔΔp < 0.01 versus the control. *p < 0.05 versus the model. **p < 0.01 versus the model.

DISCUSSION The C57BL/6 mouse model is widely used in investigating treatment for vitiligo (Lerner et al., 1986). These mice, which have black hair, show melanin granules in the hair shaft of the dorsal skin (van den Boorn et al., 2009). The formation of melanin is a complex process involving a series of physiological and biochemical processes which including melanocyte migration, division and maturation of melanocytes; formation of melanin Copyright © 2014 John Wiley & Sons, Ltd.

bodies; transportation of melanin granules; and excretion of melanin. The disappearance of epidermal pigment cells and melanin produces the loss of skin colour, which is a characteristic of vitiligo (Mishima et al., 1972; Lerner et al., 1986). Hydroquinone is a moderately effective topical agent for inhibiting hypermelanosis, which acts by inhibiting the TYR-catalysed conversion of tyrosine to melanin. TYR is the rate-limiting enzyme in melanin synthesis (Denton et al., 1952; Palumbo et al., 1991). Depigmentation has been reported in animals from the topical application of hydroquinone (Brun, 1960; Boissy and Manga, 2004), and a clinical study using a cream containing 2% hydroquinone effectively decreased hypermelanosis without untoward effects in 63.5% of 93 patients tested (Fitzpatrick et al., 1966). 8-MOP, the positive control in our study, is used clinically for treating vitiligo (He et al., 2005), and its mechanism of action is thought to be promotion of TYR activity, melanin synthesis and melanocyte proliferation (Lei et al., 1998). Our results showed that, in the vitiligo C57BL/6 hydroquinone mouse model, the hair colour was paler than that of the untreated control group, with a piebald spot on the dorsal skin. Histological analysis showed that the number of melanin-containing follicles, the basal melanocytes and melanin-containing epidermal cells was all decreased by the treatment with hydroquinone compared with the control group. The melanocytes responsible for hair pigmentation are located in the bulb of the follicle where they transfer melanin to cortical keratinocytes of the hair shaft (Commo et al., 2004), and the number of melanin-containing hair follicles directly determines the colour of the hair. Meanwhile, the number of melanin-containing hair follicles was less than that of the control group because the activity of TYR was decreased by hydroquinone. The number of melanin-containing hair follicles was also significantly increased at all dosage of galangin treatment compared with the model vitiligo group. Although vitiligo is an acquired achromia of the skin, the essential cause is a defect in melanogenesis, and several studies have focused on the histopathology of basal melanocytes in the lesional areas of skin. It has been shown that physiologically active melanocytes, and basal melanocytes exhibiting dopa or TYR activity on incubation with suitable substrates, are absent or seldom present in lesional areas of vitiligo (Jarrett and Szabo, 1956). In the dopa-oxidase staining experiment, the number of basal melanocytes increased significantly after administration of galangin, suggesting that it may play a role in the proliferation of basal melanocytes. The number of melanin-containing epidermal cells also increased significantly, indicating that galangin could improve vitiligo induced by hydroquinone in mice. Tyrosinase is the rate-limiting enzyme of melanin synthesis and thus plays an important role in melanin synthesis, and anti-TYR antibodies have been detected in many vitiligo patients. In our study, the concentration of TYR in serum and the expression of TYR protein in the dorsal skin of the vitiligo model group were significantly lower than those of the untreated control group, which is consistent with previous reports (Baharav et al., 1996; Song, 1997; Kemp et al., 1999). After administration of galangin, concentrations of TYR and expression of TYR protein were increased significantly, suggesting these may contribute to the mechanisms by which galangin alleviates vitiligo in this model. Phytother. Res. (2014)

EFFECTS OF GALANGIN ON MICE VITILIGO MODEL

Oxidative stress has been proposed as a predisposing factor in the melanocyte reduction found in vitiligo (Agrawal et al., 2004; Koca et al., 2004). MDA is an endproduct of lipid peroxidation reactions and is accepted as a specific indicator of oxidative stress. Higher levels of MDA have been detected in serum of vitiligo patients together with lower levels of Superoxide dismutase (SOD), vitamins C and E and total antioxidant activity, confirming that oxidative stress may cause melanocyte damage and play an important role in the pathogenesis of vitiligo (Yildirim et al., 2004; Arican and Kurutas, 2008). Autonomic dysfunction in vitiligo patients may be due to increase in CHE activity, by enhancing the metabolism of acetylcholine and thus sympathetic activity and decreasing parasympathetic nervous excitability. Abnormally, high levels of MDA and CHE may reduce the synthesis of melanin and induce the occurrence of vitiligo (Akrem et al., 2009). Our results confirmed that these parameters were increased in the serum of the vitiligo model group and the content of MDA and activity of CHE were decreased by administration with galangin, so this may be another mechanism involved in the effects observed after treatment with galangin. The purpose of this study was to investigate the effect of galangin in a vitiligo model induced by hydroquinone in C57BL/6 mice and its potential mechanisms. The results showed that the hair of mice turned darker after treatment with all doses of galangin and 8-MOP and that the number of melanin-containing hair follicles was increased. The numbers of basal melanocytes and melanin-containing epidermal cells were also increased

significantly at a dose of 4.25 mg/kg of galangin, but not in the 8-MOP group, perhaps because the mechanism of 8-MOP action may not involve basal melanocytes and melanin-containing epidermal cells. The concentrations of TYR in serum were increased, and the content of MDA and activity of CHE were decreased, at all dosages of galangin groups compared with the vitiligo model group. The expression of TYR protein was increased by 4.25 mg/kg galangin. Galangin and 8-MOP were both able to improve vitiligo induced by hydroquinone in mice, but 8-MOP causes irritation and has toxic side effects including loss of appetite and anaemia (Fan et al., 2006), whereas galangin treatment is associated with a low incidence of adverse effects (Zhang, et al., 2013). Our results therefore support the traditional use of A. officinarum for the treatment of vitiligo and show that galangin deserves further, more in-depth study for its potential development as a treatment for this distressing disease.

Acknowledgements This research was supported by the National Natural Science Foundation of China (grant no. 81160556) and Xinjiang Uighur autonomous Region (grant no. 2014003, 201491174, XJYS1104-2013-01)

Conflict of Interest The authors have declared that there is no conflict of interest.

REFERENCES Agrawal D, Shajil E, Marfatia Y, Begum R. 2004. Study on the antioxidant status of vitiligo patients of different age groups in Baroda. Pigment Cell Res 17: 289–294. Akrem J, Mrabet Y, Mohamed H. 2009. Oxidative stress in experimental vitiligo C57Bl/6 mice. Indian J Dermatol 54: 221–224. Arican O, Kurutas EB. 2008. Oxidative stress in the blood of patients with active localized vitiligo. Acta Dermatovenerol Alp Panonica Adriat 17: 12–16. Baharav E, Merimski O, Shoenfeld Y, Zigelman R, et al. 1996. Tyrosinase as an autoantigen in patients with vitiligo. Clin Exp Immunol 105: 84–88. Birbeck MS, Breathnach AS, Everall JD. 1961. An electron microscope study of basal melanocytes and high-level clear cells (langerhans cells) in vitiligo1. J Investig Dermatol 37: 51–64. Boissy RE, Lamoreux ML. 1988. Animal models of an acquired pigmentary disorder--vitiligo. Prog Clin Biol Res 256: 207–218. Boissy RE, Manga P. 2004. On the etiology of contact/ occupational vitiligo. Pigment Cell Res 17: 208–214. van den Boorn JG, Konijnenberg D, Dellemijn TA, et al. 2009. Autoimmune destruction of skin melanocytes by perilesional T cells from vitiligo patients. J Investig Dermatol 129: 2220–2232. Brun R. 1960. Zur experimentellen depigmentierung. J Soc Cosmet Chem 11: 571–580. Commo S, Gaillard O, Bernard BA. 2004. Human hair greying is linked to a specific depletion of hair follicle melanocytes affecting both the bulb and the outer root sheath. Br J Dermatol 150: 435–443. Denton CR, Lerner AB, Fitzpatrick TB. 1952. Inhibition of melanin formation by chemical agents. J Investig Dermatol 18: 119–135. Falabella R. 2000. 24:Surgical therapies for vitiligo. Vitiligo: A Monograph on the Basic and Clinical Sciences 193–194. Fan JY, Yang HL, Liu ZR. 2006. The treatment of vitiligo. Chin J Aesthet Med 15: 1198–1200. Fitzpatrick T, Arndt K, Mofty AE, et al. 1966. Hydroquinone and psoralens in the therapy of hypermelanosis and vitiligo. Arch Dermatol 93: 589. Copyright © 2014 John Wiley & Sons, Ltd.

He W, Han RL, Luo SD. 2005. Study of the therapeutic effect of 8-methoxypsoralen liposome gel on leukodermia in guinea-pig models. China Pharmacy 16: 92–94. Heo MY, Sohn SJ, Au WW. 2001. Anti-genotoxicity of galangin as a cancer chemopreventive agent candidate. Mutat Res Rev Mutat Res 488: 135–150. Jarrett A, Szabo G. 1956. The pathological varieties of vitiligo and their response to treatment with meladinine. Br J Dermatol 68: 313–326. Kemp EH, Waterman EA, Gawkrodger DJ, et al. 1999. Identification of epitopes on tyrosinase which are recognized by autoantibodies from patients with vitiligo. J Investig Dermatol 113: 267–271. Koca R, Armutcu F, Altinyazar H, Gürel A. 2004. Oxidantantioxidant enzymes and lipid peroxidation in generalized vitiligo. Clin Exp Dermatol 29: 406–409. Lei TC, Zhu WY, Xia MY, et al. 1998. Study on regulation of melanogenesis induced by 8-methoxypsoralen and related signal transduction pathways in murine melanoma cells. Pigment Cell Res 11: 396. Lerner AB, Shiohara T, Boissy RE, et al. 1986. A mouse model for vitiligo. J Invest Dermatol 87: 299–304. Manga P, Orlow SJ. 2012. Engineering a new mouse model for vitiligo. J Invest Dermatol 132: 1752–1755. Matsuda H, Higashino M, Nakai Y, et al. 1996. Studies of cuticle drugs from natural sources. Iv. Inhibitory effects of some arctostaphylos plants on melanin biosynthesis. Biol Pharm Bull 19: 153–156. Mishima Y, Kawasaki H, H Pinkus. 1972. Dendritic cell dynamics in progressive depigmentations. Distinctive cytokinetics of dendritic cells revealed by electron microscopy. Arch Dermatol Forsch 243: 67–87. Palumbo A, d’Ischia M, Misuraca G, et al. 1991. Mechanism of inhibition of melanogenesis by hydroquinone. Biochim Biophys Acta 1073: 85–90. Seymour H. 1963. Separation, purification, and properties of two tyrosinases from hamster melanoma. J Biol Chem 238: 2351–2357. Phytother. Res. (2014)

S.-X. HUO ET AL. Porter J, Beuf AH, Lerner A, et al. 1987. Response to cosmetic disfigurement: patients with vitiligo. Cutis cutaneous med practitioner 39: 493. Russo A, Longo R, Vanella A. 2002. Antioxidant activity of propolis: role of caffeic acid phenethyl ester and galangin. Fitoterapia 73: S21–S29. Song Y-H. 1997. Why tyrosinase for treatment of melanoma. The Lancet 350: 82–83. Taieb A, Picardo M. 2009. Clinical practice. Vitiligo. N Engl J Med 360: 160–169. Takeuchi S, Zhang W, Wakamatsu K, et al. 2004. Melanin acts as a potent UVB photosensitizer to cause an atypical mode of cell death in murine skin. Proc Natl Acad Sci U S A 101: 15076–15081.

Copyright © 2014 John Wiley & Sons, Ltd.

Tuerxun YS. 1999. Drug Standard of Ministry of Public Health of the People’s Republic of China(Uygur Medicine). Xinjiang Science and Technology Publishing House: Urumqi. Vries TJ, Trancikova D, Ruiter DJ, et al. 1998. High expression of immunotherapy candidate proteins gp100, MART-1, tyrosinase and TRP-1 in uveal melanoma.Br J Cancer 78: 1156–1161. Yildirim M, Baysal V, Inaloz H, Can M. 2004. The role of oxidants and antioxidants in generalized vitiligo at tissue level. J Eur Acad Dermatol Venereol 18: 683–686. Zhang HT, Li N, Wu J, et al. 2013. Galangin inhibits proliferation of HepG2 cells by activating AMPK via increasing the AMP/TAN ratio in a LKB1-independent manner. Eur J Pharmacol 718: 235–244.

Phytother. Res. (2014)

The effects of galangin on a mouse model of vitiligo induced by hydroquinone.

Galangin, the main active component of Alpinia officinarum Hance, was tested in a mouse model of vitiligo induced in C57BL/6 mice by the topical appli...
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