Pharmacodynamics of frigid zone plant Taxus cuspidata S.et Z.against skin melanin deposition,oxidation,inflammation and allergy

Background:Taxus cuspidata S.et Z.is a precious species of frigid zone plant belonging to the Taxaceae family,which possesses anticancer,anti-inflammatory,hypoglycemic,and antibacterial pharmacological properties.While taxane extracted from Taxus chinensis has been reported to elicit antioxidant activities,whether Taxus cuspidata S.et Z.has skin-protective actions against injuries remained unknown.This study aims to explore the pharmacological effects of three Taxus extracts on skin melanin deposition,oxidation,inflammation,and allergy so as to provide new ideas for the prevention and treatment of various diseases related to skin damage.Methods:Skin melanin deposition was evaluated by measuring melanin content in the skin of guinea pigs by alkali lysis method.Antioxidant capacity was evaluated by measuring superoxide dismutase(SOD)concentration and glutathione(GSH)content in skin tissue homogenates of Kunming mice by SOD assay kit and micro reduced GSH assay kit.The quantitative real-time polymerase chain reaction(qRT-PCR)and western blotting were used to examine the levels of both SOD and recombinant glutathione peroxidase 4(GPX4).Skin inflammation was evaluated by xylene-induced ear swelling test and egg-white-induced paw swelling test in mice.In a mouse model of skin allergy induced by 4-aminopyridine(4-AP),allergy was determined by licking body counts and histamine concentrations in tissue homogenates using enzyme-linked immunosorbent assay(ELISA)kits.Two proinflammatory factors tumor necrosis factor(TNF)-αand interleukin(IL)-1βwere measured by qRT-PCR.Hematoxylin and eosin(HE)staining was conducted to assess the degree of skin lesion.Results:All three Taxus extracts including Taxus chinensis essential oil,Taxus chinensis extract and Taxus chinensis extract compound reduced the melanin deposits in the back skin relative to the non-treated control animals,of which Taxus chinensis essential oil produced the greatest effect.In contrast,the three Taxus extracts elevated SOD and GSH levels in the skin tissues,and the highest increase was seen with Taxus chinensis essential oil.Three Taxus extracts,especially Taxus chinensis essential oil,effectively reduce the rate of ear and paw swelling.All three Taxus extracts reduced the number of body licks,the levels of TNF-αand IL-1β,and the histamine content in tissue homogenates of mice and alleviated skin damage.Consistently,Taxus chinensis essential oil yielded the greatest magnitude of decreases.Conclusion:While all three Taxus extracts possessed the anti-skin melanin deposition,oxidation,and allergy properties,Taxus chinensis essential oil produced the superior effects.

Expression and contribution of microphthalmia-associated transcription factor to the melanin deposition in Liancheng white ducks

The present study investigates the expression of microphthalmia-associated transcription factor(MITF) and its contribution to the melanin deposition in Liancheng white ducks.Nested PCR was used to clone the MITF gene sequence from the skin tissue of female Liancheng white ducks.Ultraviolet spectrophotometry was used to detect the melanin deposition.MITF mRNA expression and melanin deposition in different tissues and organs were detected and their correlation was analyzed.The MITF gene(GenBank number: MG516570) was 1 323 bp in length,contains a complete CDS region(34-1 323 bp) and codes 429 amino acids with 100% homology to the MITF of Anas platyrhynchos and over 95% homology to those of Gallus gallus and Coturnix japonica.Genetic evolution analysis reveals a close relationship of Liancheng white ducks with A.platyrhynchos,and also to lesser extents with Anser cygnoides,silky fowl and G.gallus,as well as Sus scrofa,Ovis aries and other mammals.Real-time quantitative PCR(qPCR) analysis demonstrated that MITF was expressed in skin,gizzard,liver,kidney and muscle,and of these tissues,its expression was the highest in the skin tissue(skin>gizzard>liver>kidney>muscle).Ultraviolet spectrophotometry showed that melanin deposition was positively correlated with the MITF expression level in these five tissues and organs(P<0.05).Together,these results demonstrated a tissue-specific pattern of MITF expression and a positive correlation between MITF expression and melanin deposition,indicating that MITF expression may contribute to the melanin deposition in Liancheng white ducks.

Dietary aflatoxin B1 induces abnormal deposition of melanin in the corium layer of the chicken shank possibly via promoting the expression of melanin synthesis-related genes

San-Huang chicken is a high-quality breed in China with yellow feather, claw and break. However, the abnormal phenomenon of the yellow shank turning into green shank of San-Huang chicken has been a concern, as it seriously reduces the carcass quality and economic benefit of yellow-feathered broilers. In this study, the cause of this abnormal green skin in shank was systematically investigated. Physiological anatomy revealed that the abnormal skin in shank was primarily due to the deposition of melanin under the dermis. After analyzing multiple potential causes such as heredity(pedigree and genetic markers), environment(water quality monitoring) and feed composition(mycotoxin detection), excessive aflatoxin B1(AFB1) in feed was screened, accompanied with a higher L-dihydroxy-phenylalanine(L-DOPA)(P<0.05) and melanin content(P<0.01). So it was speculated that excessive AFB1 might be the main cause of abnormal green skin in shank. Subsequently, the further results showed that a high concentration of AFB1(>170 μg kg–1)indeed induced the abnormal green skin in shank compared to the normal AFB1 content(<10 μg kg–1), and the mRNA levels of TYR, TYRP1, MITE, MC1R and EDN3 genes related to melanin deposition would significantly up-regulate(P<0.01) and the content and activity of tyrosinase(TyR) significantly increased(P<0.05). At the same time, the content of L-DOPA and melanin deposition also increased significantly(P<0.01), which also confirmed the effect of excessive AFB1 on melanin deposition in skin of shank. Results of additional experiments revealed that the AFB1's negative effect on melanin deposition in skin of shank could last for a longer time. Taken together, the results of this study explained the occurrence and possible mechanisms of the abnormal AFB1-related green skin in shank of chickens. Excessive AFB1 in diets increased the L-DOPA content and melanin abnormal deposition in the chicken shank possibly via promoting TyR content and activity, and the expression of melanin synthesis-related genes. Furthermore, our findings once again raised the alarm of the danger of AFB1 in the broiler production.