光甘草定-富勒醇联合应用对抑制酪氨酸酶活性和清除DPPH·的协同作用

目的:探索富勒醇与光甘草定联合应用对酪氨酸酶活性的影响及对DPPH·的清除效果。方法:采用比色法测定光甘草定、富勒醇单独及联合应用对酪氨酸酶活性的抑制及对DPPH·的清除作用。结果:光甘草定对酪氨酸酶的活性有抑制作用,IC50为20.38μmol·L-1;富勒醇对酪氨酸酶仅有很微弱的活性抑制作用且无IC50值;光甘草定、富勒醇清除DPPH·的IC50分别为14.31,47.66 mg·L-1。低浓度光甘草定与富勒醇联合应用,体系对酪氨酸酶的抑制活性明显增强;清除DPPH·的效能也同样增强,合并指数为0.72。结论:低浓度光甘草定与富勒醇联合对酪氨酸酶的抑制作用明显增强;同时,对DPPH·的清除效率呈现协同作用。     

甘草提取物对酪氨酸酶活性的抑制作用

目的研究甘草提取物对酪氨酸酶活性的抑制作用。方法用50%(V/V)乙醇提取甘草中的有效成分,分别以L-酪氨酸、邻苯二酚为底物,在475、390nm处测定溶液的吸光度,观察甘草提取物对单酚酶、双酚酶活性的影响。结果50%(V/V)乙醇甘草提取物对酪氨酸酶有明显的抑制作用(IC50分别为1.94、2.94mg·ml-1)。结论甘草提取物对酪氨酸酶单酚酶、双酚酶的活性均有抑制作用;以邻苯二酚为底物的双酚酶活性测定体系可较好地应用于酪氨酸酶活性的研究。     

甘草黄酮对酪氨酸酶的抑制作用研究

目的研究甘草黄酮对酪氨酸酶的抑制作用。方法以甘草黄酮为材料,通过测定其对酪氨酸单酚酶及二酚酶的抑制活性,并分析其对酪氨酸酶抑制的动力学模型,来评价其抑制酶活性强弱与判断其抑制类型。结果甘草黄酮可有效抑制酪氨酸酶单酚酶与二酚酶的活性,在实验浓度范围内,甘草黄酮对单酚酶、二酚酶活性的抑制率分别为81.26%、76.52%,其IC_(50)值分别为0.524、1.254 mg·mL~(-1)。L-多巴氧化体系动力学分析结果表明,甘草黄酮对酪氨酸酶的抑制类型为可逆性竞争性抑制,由米氏方程可知,随着黄酮浓度的增加,K_m值逐渐增大,V_m值基本保持不变。结论甘草黄酮对酪氨酸酶有较强的抑制作用,可作为潜在的美白剂应用于药学和化妆品行业中。     

三叶青提取物对A375细胞增殖、酪氨酸酶活性及黑色素合成的影响

目的 探讨三叶青乙醇提取物对人恶性黑色素瘤A375细胞增殖、酪氨酸酶活性及黑色素合成的影响.方法 采用MTT比色法,测定不同浓度三叶青乙醇提取物对A375细胞体外抑制作用;比色法测定酪氨酸酶活性和黑色素含量.结果 在质量浓度为1～625μg/ml范围内,随着三叶青乙醇提取物浓度增大可抑制A375细胞的增殖(P＜0 01...     

三叶青提取物对A375细胞增殖、酪氨酸酶活性及黑色素合成的影响

目的探讨三叶青乙醇提取物对人恶性黑色素瘤A375细胞增殖、酪氨酸酶活性及黑色素合成的影响。方法 采用MTT比色法,测定不同浓度三叶青乙醇提取物对A375细胞体外抑制作用;比色法测定酪氨酸酶活性和黑色素含量。结果在质量浓度为1～625μg/ml范围内,随着三叶青乙醇提取物浓度增大可抑制A375细胞的增殖(P<0.01);三叶青乙醇提取物浓度在1～5μg/ml时,对酪氨酸酶活性和黑色素合成抑制有增加趋势;而在25～625μg/ml时,对A375细胞有一定毒性。结论三叶青乙醇提取物在一定浓度范围内(1～625μg/ml)能抑制A375细胞的增殖,且呈剂量依赖关系。     

维药没食子对酪氨酸酶抑制作用的研究

目的研究维药没食子对酪氨酸酶活性的影响。方法以L-酪氨酸作为底物,测定来源于没食子药材中的没食子酸、1,2,3,6-四-O-没食酰基-β-D-葡萄糖苷及没食子总鞣质提取物干预前、后酪氨酸酶的活性的变化,计算酪氨酸酶抑制率。结果没食子酸、1,2,3,6-四-O-没食酰基-β-D-葡萄糖苷及没食子总鞣质提取物对酪氨酸酶的活性均具有明显下调作用,其中1,2,3,6-四-O-没食酰基-β-D-葡萄糖苷对酪氨酸酶的抑制作用最强。结论该研究为深入开发利用没食子药材中的美白成分提供了依据。     

氢化可的松对B-16黑素瘤细胞酪氨酸酶及黑素生成影响研究

目的　探讨氢化可的松体外对酪氨酸酶活性影响 ,以及对小鼠B 16黑素瘤细胞株细胞增殖、黑素合成以及细胞内酪氨酸酶活性的作用。方法　利用四甲基偶氮唑蓝(MTT)比色法测定药物对细胞增殖的影响 ;采用酶学方法研究药物对酪氨酸酶活性的影响 ;用 5 70nm比色法测定黑素含量。结果　氢化可的松体外可激活酪氨酸酶活性 ,增强B16鼠黑素瘤细胞增殖 ,提高酪氨酸酶和黑色素合成能力。结论　氢化可的松可增强酪氨酸酶活性 ,进而促进黑素合成。     

银杏叶中抑制酪氨酸酶活性的成分研究

目的 探明银杏叶中对酪氨酸酶具有抑制作用的活性成分。方法 以体外酪氨酸酶活性抑制检测为导向，对银杏叶提取物中具有抑制活性的萃取部位采用正相、反相硅胶柱色谱和制备HPLC等方法进行逐级分离纯化，获得部分具有抑制活性的化合物，并采用核磁等波谱技术鉴定其结构。结果 从银杏叶95%乙醇提取物中分离纯化，获得了5个对酪氨酸酶具有抑制活性的化合物，分别鉴定为：白果内酯(Ⅰ)、原儿茶酸(Ⅱ)、对香豆酸(Ⅲ)、对羟基苯甲酸(Ⅳ)、间羟基苯甲酸(Ⅴ)。结论 银杏叶中含有能抑制酪氨酸酶的活性成分，具有开发成抑制皮肤黑色素生成药物或美白化妆品的潜在应用价值。     

4味中药乙醇提取物祛黄褐斑作用的比较研究

目的比较白附子、银花、白芨、六月雪4味中药乙醇提取物祛黄褐斑作用的差异,选出作用最强的药材。方法以MTT法测定小鼠B16黑素瘤细胞增殖抑制率、酪氨酸酶活性、黑素含量变化;采用多重比较法进行统计分析。结果银花的浓度为62.5μg.mL-1,白芨、白附子各浓度(500、250、125、62.5μg.mL-1)均对B16鼠黑素瘤细胞增殖抑制作用较强。白附子的浓度为250μg.mL-1或银花的浓度为62.5μg.mL-1对小鼠B16黑素瘤细胞酪氨酸酶活性抑制作用最佳。白附子的浓度为125μg.mL-1对黑素合成抑制作用最好。结论白芨与白附子可作为祛黄褐斑有效成分的候选药材。     

杏仁油对黑色素瘤细胞B16细胞增殖及黑素合成的影响

目的探讨杏仁油对小鼠黑色素瘤细胞B16增殖及黑素合成的影响。方法采用MTT法测定杏仁油对小鼠黑色素瘤细胞B16增殖的影响,L-dopa氧化法测定酪氨酸酶活性,NaOH裂解法测定黑素合成。结果杏仁油浓度在0.1～100μg/mL时对小鼠黑色素瘤细胞B16增殖无影响(P>0.05),对酪氨酸酶活性和黑素含量均呈浓度依赖性抑制,均具有显著性抑制作用(P<0.05)。结论杏仁油对黑色素瘤细胞B16酪氨酸酶活性和黑素生成有较强的剂量相关性抑制作用。     

虎杖提取物对神经病理性疼痛模型大鼠的镇痛作用研究

目的：研究虎杖提取物对神经病理性疼痛模型大鼠的镇痛作用,并探讨其作用机制。方法雄性SD大鼠,随机分为对照组和坐骨神经缩狭模型（chronic construction injury, CCI）组。CCI术后14 d,应用Von Frey法测定机械刺激缩足反射阈值（mechanical withdrawal threshold, MWT）,观察口服不同剂量的虎杖提取物对CCI大鼠机械性痛觉超敏的影响。并考察不同剂量虎杖提取物对CCI大鼠脊髓p-ERK、p-P38水平及小胶质细胞活化的影响。结果虎杖提取物可明显升高CCI大鼠术侧的MWT值（P〈0.05）,而对正常大鼠的MWT值没有显著影响（P〉0.05）。同时虎杖提取物可显著抑制CCI模型大鼠脊髓ERK和p38的磷酸化,并显著抑制IBA-1表达增加。结论虎杖提取物对CCI诱导的机械性痛觉超敏具有显著性的抑制作用,且镇痛作用维持时间长于吗啡,其机制可能是通过抑制脊髓水平ERK和p38的磷酸化,及通过抑制小胶质细胞活化而实现。     

Mulberroside F isolated from the leaves of Morus alba inhibits melanin biosynthesis

The current study was carried out to investigate the in vitro effects of an 85% methanol extract of dried Morus alba leaves on melanin biosynthesis, which is closely related to hyperpigmentation. These extracts inhibited the tyrosinase activity that converts dopa to dopachrome in the biosynthetic process of melanin. Mulberroside F (moracin M-6, 3'-di-O-beta-D-glucopyranoside), which was obtained after the bioactivity-guided fractionation of the extracts, showed inhibitory effects on tyrosinase activity and on the melanin formation of melan-a cells. This compound also exhibited superoxide scavenging activity that is involved in the protection against auto-oxidation. But its activity was low and was weaker than of kojic acid. These results suggest that mulberroside F isolated from mulberry leaves might be used as a skin whitening agent.     

驱白艾力勒思亚散乙醇提取物对小鼠B16黑素瘤细胞增殖及黑素生成的影响

目的研究维药复方驱白艾力勒思亚散(QBALLSYS)乙醇提取物对小鼠B16黑素瘤细胞增殖、黑素合成以及酪氨酸酶活性的影响。方法以MTT法测定培养的B16黑素瘤细胞的增殖活性;氢氧化钠法测定黑素生成量;体外氧化多巴反应方法测定酪氨酸酶活性。结果与空白对照组相比,驱白艾力勒思亚散乙醇提取物对B16黑素瘤细胞的增殖活性、黑素生成量、酪氨酸酶活性均有显著性作用(P<0.05或P<0.01)。驱白艾力勒思亚散乙醇提取物对小鼠B16黑素瘤细胞的增殖活性有上调作用,对细胞黑素生成以及酪氨酸酶的活性均有不同程度的促进作用。结论驱白艾力勒思亚散的乙醇提取物具有促进黑素细胞增殖和合成黑素的作用。     

Inhibitory effects of Morinda citrifolia extract and its constituents on melanogenesis in murine B16 melanoma cells

The objective of this study was to examine the effects of Morinda citrifolia (noni) extract and its constituents on α-melanocyte stimulating hormone (α-MSH)-stimulated melanogenesis in cultured murine B16 melanoma cells (B16 cells). A 50% ethanolic extract of noni seeds (MCS-ext) showed significant inhibition of melanogenesis with no effect on cell proliferation. MCS-ext was more active than noni leaf and fruit flesh extracts. Activity guided fractionation of MCS-ext led to the isolation of two lignans, 3,3'-bisdemethylpinoresinol (1) and americanin A (2), as active constituents. To elucidate the mechanism of melanogenesis inhibition by the lignans, α-MSH-stimulated B16 cells were treated with 1 (5?μM) and 2 (200?μM). Time-dependent increases of intracellular melanin content and tyrosinase activity, during 24 to 72?h, were inhibited significantly by treatment with the lignans. The activity of 1 was greater than that of 2. Western blot analysis suggested that the lignans inhibited melanogenesis by down regulation of the levels of phosphorylation of p38 mitogen-activated protein kinase, resulting in suppression of tyrosinase expression.     

Inhibitory effects of plant extracts on tyrosinase, L-DOPA oxidation, and melanin synthesis

For medical, pharmacological, and cosmetic reasons, the demand for effective and safe depigmentating agents has increased. In this study, 101 plant extracts (methanol or water extracts) were screened for their inhibitory activities against tyrosinase, (L-3, 4,-dihydroxyphenylalanine) L-DOPA oxidation, and melanin biosynthesis in B16 mouse melanoma cells. Of the extracts examined, 31 showed over 50% inhibition of mushroom tyrosinase at a concentration of 666 microg/Ml, and 11 inhibited L-DOPA auto-oxidation at this concentration. In particular, extracts of Broussonetia kazinoki var. humilis (leaves and stems), Broussonetia papyrifera (leaves and bark), Cornus officinalis (fruit), Rhus javanica (gallnut), and Pinus densiflora (leaves) inhibited both tyrosinase activity and L-DOPA oxidation in a concentration-dependent manner. Seventeen plant extracts that inhibited tyrosinase were further tested for their inhibitory effects on melanogenesis. In B16 mouse melanoma cells, extracts of Acorus gramineus, Capsella bursa-pastoris, Morus bombycis, Perilla frutescens var. crispa, Quercus dentate (bark), Rhus javanica (gallnut), Schizopepon bryoniaefolius, or Sophora flavescens markedly inhibited (>50%) melanin synthesis at 50 microg/Ml. These plants represent a potential source of novel whitening agents for ultraviolet (UV)-sensitive skin.     

Depigmentation of melanocytes by the treatment of extracts from traditional Chinese herbs: a cell culture assay

OBJECTIVE: To obtain potential skin whitening agents from traditional Chinese herbs, we tested changes of melanin content in melanocyte cell lines after treatment with extracts of 90 traditional Chinese herbs. METHODS: Mouse melanocyte cell lines were used. Depigmentation activity of the herb extracts were first screened in Mel-Ab cells, and then re-evaluated in melan-a cells and co-culture of melan-a and SP-1 cells. Melanin content and cell viability were the two indications for evaluation. Tyrosinase activity and the expression of melanin synthesis related enzymes in cells treated with the herb extracts were also tested. RESULTS: Nine herb extracts were proved to have depigmentation activity similar to or better than that of arbutin and low cytotoxicity to melanocytes. Two of them were more effective in co-cultured melan-a cells. Most of the effective herb extracts inhibited tyrosinase activity and the expression of tyrosinase. Some of them also inhibited tyrosinase related protein-1 and/or tyrosinase related protein-2 in cultured cells. CONCLUSIONS: We have found 9 herb extracts to be promising skin whitening agents. Among them, water extract of Galla Chinensis and ethanol extract of Radix Clematidis exhibited higher depigmentation activity and caused lower tyrosinase activity in cell culture assays and are worthy to be further studied.     

Inhibitory effect of artocarpanone from Artocarpus heterophyllus on melanin biosynthesis

In our previous efforts to find new tyrosinase inhibitory materials, we investigated 44 Indonesian medicinal plants belonging to 24 families. Among those plants, the extract of Artocarpus heterophyllus was one of the strongest inhibitors of tyrosinase activity. By activity-guided fractionation of A. heterophyllus wood extract, we isolated artocarpanone, which inhibited both mushroom tyrosinase activity and melanin production in B16 melanoma cells. This compound is a strong candidate as a remedy for hyperpigmentation in human skin.     

何首乌降血脂有效部位及量效关系的实验研究

目的研究何首乌降血脂的有效部位及其量效关系。方法选用CO2超临界、系统溶媒（石油醚、乙酸乙酯、正丁醇、75%乙醇、水）和水提醇沉的方法分别对何首乌进行提取,观察各提取物对腹腔注射蛋黄乳液致高血脂症模型小鼠血清总胆固醇（TC）及三酰甘油（TG）的影响,初步明确何首乌降血脂的有效活性部位,并对该有效部位进行量效关系的评定。结果何首乌超临界提取物、乙醇提取物和水提取物均有显著的降低血清TC和TG的作用,其中何首乌超临界提取物的降脂效果优于乙醇提取物和水提取物,其在0.50～1.00g/（kg.d）时降脂效果最佳;何首乌石油醚提取物、乙酸乙酯提取物和水提醇沉物虽也有一定的降血脂作用,但与对照组相比差异无统计学意义。结论何首乌超临界提取物为何首乌降血脂的有效活性部位,其有效剂量范围在0.50～1.25g/（kg.d）之间。