The effects of areca catechu L extract on anti-inflammation and anti-melanogenesis

Ethanolic extract (CC-516) from Areca catechu L was prepared and its various biological activities were evaluated, CC-516 showed potent anti-oxidative, free radical scavenging, and anti-hyaluronidase activity. Anti-oxidative effect of CC-516 (IC _ 50: 45.4 mug/ml) was lower than butylated hydroxytoluene (IC _ 50: 5mug ml), but similar to tocopherol and higher than ascorbic acid. Especially, CC-516 exhibited relatively high free radical scavenging activity (IC _ 50: 10.2 mug/ml) compared to control. CC-516 inhibited effectively hyaluronidase activity (IC _ 50: 416 mug/ml), showed inhibition in vivo on delayed hypersensitivity as well as croton-oil induced ear edema in mice when it was topically applied. These results strongly suggest that CC-516 may reduce immunoregulatory/inflammatory skin trouble. Also, from the results, we have elucidated that CC-516 showed anti-allergic and anti-cytotoxicity activity. The whitening effect of CC-516 shown by the inhibition of mushroom tyrosinase activity with IC _ 50 of 0.48 mg/ml and of melanin synthesis in B16 melanoma cells. This study indicates that CC-516 is effective on anti-inflammatory/anti-melanogenesis, and can be used as a new agent for cosmetics.     

Inhibitory Effects of 150 Plant Extracts on Elastase Activity, and Their Anti-inflammatory Effects

The inhibitory effects of 150 medicinal plants on elastase activity were investigated. Among the 150 plants, six plant extracts (final concentration 1 mg/ml in methanol) exhibited more than 65% of inhibition of elastase activity. The inhibitory effects of six active plants, including Areca catechu (IC50, 42.4 mug/ml), Cinnamonum cassia (IC50, 208.7 mug/ml), Myristica fragrans (IC50, 284.1 mug/ml), Curcuma longa (IC50, 398.4 mug/ml), Alpinia katsumadai (IC50, 465.7 mug/ml) and Dryopteris cassirrhizoma (IC50, 714.4 mug/ml) on the activity of human leukocyte elastase, hyaluronidase and lipid peroxidation were examined. In the lipid peroxidation assay, using the TBA method, three of the six plants, including Curcuma longa (IC50, 45.5 mug/ml), Areca catechu (IC50, 51.0 mug/ml) and Alpinia katsumadai (IC50, 116.3 mug/ml) exhibited more than 70% inhibition at the concentration of 1 mug/ml, but only one plant, Areca catechu (IC50, 563 mug/ml) showed high inhibitory effect on hyaluronidase activity. The results suggest that medicinal plants showing several biological activities may be potent inhibitors of the anti-ageing process in skin. This property might be useful for application in cosmetics.     

石榴皮中鞣花酸的抗衰老性能及机理研究

利用光谱法研究了石榴皮中鞣花酸的抗衰老性能和机理。首先,通过分光光度法考察了鞣花酸对DPPH·、·OH和·O2-等3种自由基的清除率和弹性蛋白酶抑制率,结果证明了鞣花酸抗衰老能力强。其次,以弹性蛋白酶为研究对象,利用光谱法探讨了鞣花酸对弹性蛋白酶的作用机理。结果表明,鞣花酸与弹性蛋白酶发生作用并形成络合物,当鞣花酸的质量浓度为4.57 mg/m L时,鞣花酸对弹性蛋白酶的抑制率高达88.26%。当鞣花酸浓度低于4.0×10-5mol/L时,其荧光猝灭机理主要是静态猝灭,鞣花酸浓度较高时动态猝灭所占比例增加。因此,鞣花酸可以作为天然自由基清除剂与弹性蛋白酶抑制剂应用于抗衰老化妆品中。     

Study of the refirming effect of a plant complex

Loss of skin elasticity is one of the main problems of ageing. This is a mechanical property influenced by elastin, a protein in the dermis which, together with collagen and glycosaminoglycans, makes up the connective tissue. This tissue is affected by a large number of events (such as cutaneous ageing, pregnancy, slimming processes and cellulitis) which eventually cause it to change. At the same time, the metabolism of the proteins of the connective tissue decreases and there is an ever greater presence of enzymes, principally elastases and collagenases, which are responsible for breaking down the elastin and the collagen. One way to prevent such a loss of elasticity is to use active ingredients that are able to inhibit elastase enzymes. A plant complex was prepared using the following plants: lady's thistle (Silybum marianum GAERTN), alchemilla or yarrow (Alchemilla vulgaris L.), horsetail (Equisetum arvense L.) as well as germinated seeds (Glycine soja Siebold and Zucc., Triticum vulgare Vilars, Medicago sativa L., Raphanus sativus L.). The complex was standardized to give the corresponding active principles, silybin, tannins, silicon and peptides, respectively, and in vitro enzymatic tests were carried out to establish its ability to inhibit elastase. The study of enzymatic inhibition was carried out using two enzymes: (1) porcine pancreatic elastase (PPE), and (2) human leukocyte elastase (HLE). The results showed that the plant complex presents non-competitive inhibition in the order of 41.0% against PPE and 50.0% against HLE. An in vivo test was made alongside the in vitro test using an SEM 474 Cutometer (Courage & Khazaka) to study the elasticity of the skin, and positive effects were obtained when applying a cosmetic formulation containing 5% of the plant complex. Image analysis of duplicates of the cutaneous surface, before and after treatment began with a product containing 5% of plant complex and showed that wrinkles were decreased by 36.7%.     

以秀丽隐杆线虫为模式生物的蓝莓果酒抗氧化及抗衰研究

为探讨不同组分的蓝莓果酒对秀丽隐杆线虫抗氧化性能与抗细胞凋亡的影响,从而确定蓝莓果酒中主要物质的浓度及食用功能特性。以秀丽隐杆线虫(Caenorhabditis elegans)为模式生物,a组在蓝莓果酒的酒精度(体积分数)为14%的基础上,通过改变其原花青素(proanthocyanidin,PC)含量设置6个喂食组,b组在蓝莓果酒的原花青素含量为3mg/mL的基础上,通过改变其酒精度设置7个喂食组,对照组线虫以大肠杆菌OP50喂养,检测各组线虫的抗氧化酶活力以及细胞凋亡情况。结果表明:蓝莓酒中的原花青素是延缓衰老的有效成分,低浓度酒精(10%)也能延缓衰老,但是当酒精度(体积分数)高于10%时,则具有反作用,原花青素浓度为3mg/mL、酒精度(体积分数)为10%的蓝莓果酒对线虫的抗衰老作用最佳。     

Inhibitory effects of natural plants of Jeju Island on elastase and MMP-1 expression

In order to search for new active cosmetic ingredients of natural origin, we screened about 60 plants collected from Jeju Island, which is located in the southernmost part of the Republic of Korea. We investigated their free radical scavenging activity, elastase inhibition activity, and reduction of MMP-1 mRNA expression for the development of anti-aging ingredients as raw materials for use in cosmetics. In the free radical scavenging capacity assay, 12 extracts, including Typha orientalis (seed) and Torreya nucifera (leaf), showed significant free radical scavenging activity (up to SC50 < 30 μg/ml). Among these extracts, Nymphaea tetragona (rhizome) extract showed the highest free radical scavenging activity (SC50 = 4.7 μg/ml). In the anti-elastase inhibition assay, seven extracts, including T. orientalis (seed) and Persicaria hydropiper (whole plant), showed high inhibitory activity (>50% at 100 μg/ml). Among these extracts, P. hydropiper (whole plant) extract showed the highest elastase inhibition activity (IC50 = 46.7 μg/ml). In the MMP-1 expression assay using RT-PCR, T. orientalis (seed), Pyrrosia hastata (root), and Capsicum annum (whole plant) showed slightly lower inhibition activity than EGCG, which was used as a control. Furthermore, four extracts, including P. hydropiper (whole plant), Filipendula glaberrima (root), N. tetragona (root), and Camellia japonica (leaf), completely inhibited the expression of MMP-1 in human fibroblast cells. The results showed that four of the 60 plant extracts may hold potential for use as natural active ingredients for anti-aging cosmetics.     

Inhibition of human neutrophil elastase by wheat ceramides

Ceramides, composed of sphingosine N -acyl linked to fatty acids have become widely used in cosmetology. They play several physiological roles in the regulation of skin barrier function. Human neutrophil elastase (HNE) can be inhibited by long-chain fatty acids and their derivatives; it was therefore postulated that plant ceramides could be inhibitors of HNE. Ceramides were extracted from wheat, isolated and characterized. The main fatty acids were 16:0, 18:1, 18:2 and the sphingoid moiety was phytosphingosine. Concentrations necessary to reach 50% inhibition of HNE were, respectively, 33 and 41 μg ml^-1 for non-glycosyl ceramides (CER) and glycosyl ceramides (gly-CER) when using a synthetic specific substrate. Similar extents of inhibition were obtained using a physiological substrate, insoluble elastin. Ex vivo studies showed that CER protected human skin elastic fibres against HNE degradation. Ceramides, being natural non-toxic substances, besides their role in cosmetics, could be of pharmacological interest in dermal inflammatory disorders.     

Identification of novel peptides with high stability against in vitro hydrolysis from bovine elastin hydrolysates and evaluation of their elastase inhibitory activity

Surviving in the gastrointestinal tract is crucial for biopeptides to exert physiological effects in vivo. To enrich elastase inhibitory peptides with high digestive stability, elastin peptides was separated by using ultrafiltration and macroporous resin column, then changes in elastase inhibitory activity, amino acid composition and peptide profile of elastin peptides during in vitro digestion were measured. The results revealed that the fraction F3 eluted by 40% ethanol displayed high digestive stability possibly due to the high content of Pro-containing peptides (20.25%). Particularly, thirty peptides in F3 exhibited high digestive stability and most of them contained GV and/or PG fragment. Since GV and PG could inhibit 35.70% and 51.77% elastase activity at the concentration of 20 mm , respectively, peptides in F3 survived in in vitro digestion which contained GV and PG sequence might be potential elastase inhibitors. This provides an approach for preparation of peptides with high bioactivity and digestive stability.     

羊乳酪蛋白酶解物对秀丽线虫衰老的改善作用

该研究利用秀丽隐杆线虫（Caenorhabditis elegans）模型研究了羊乳酪蛋白酶解物（Goat Milk Casein Hydrolysates,GMCH）的抗衰老及体内外抗氧化作用。通过对比GMCH实验组和大肠杆菌对照组秀丽线虫的寿命、运动能力、脂褐素水平等指标来研究GMCH的抗衰老作用,通过自由基清除实验以及测定线虫体内抗氧化酶活性评价GMCH的体内外抗氧化活力,同时测定秀丽线虫在过氧化氢、百草枯及热应激条件下的寿命。结果表明,与对照组相比,喂食0.1 mg/mL羊乳酪蛋白酶解物的线虫的平均寿命延长9.33%,体内脂褐素水平降低了65.00%,同时GMCH对线虫的生殖能力和运动能力没有负面影响,对线虫氧化应激和热应激有一定的保护作用;GMCH具有一定的体外抗氧化能力并且能够提高线虫体内抗氧化酶活力,与对照组相比,实验组SOD活力提高43.30%、CAT活力提高124.40%、GSH活力提高176.90%、MDA含量降低78.70%。综上所述,GMCH能够延长线虫的寿命,降低线虫体内脂褐素积累,提高线虫在应激条件下的抵抗能力和体内抗氧化酶活力,具有较好的抗衰老活性。     

猪皮胶原多肽的体外抗氧化特性研究

以猪皮胶原多肽为原料,研究其羟自由基清除能力、还原能力、对Fe2+诱导的脂质过氧化抑制能力以及对猪油氧化的抑制效果,考察其体外抗氧化特性.结果表明:在10mg/mL～50mg/mL浓度范围内,猪皮胶原多肽具有一定的羟自由基清除能力、还原能力和对Fe2+诱导的脂质过氧化抑制能力,且随着浓度的增加抗氧化作用也增强,当浓度为50mg/mL时,对羟自由基的清除率为56.38％,还原力为0.909,对Fe2+诱导的脂质过氧化抑制率为43.34％;不同添加量的猪皮胶原多肽对猪油氧化均有明显的抑制作用,当添加量为2％时,抗氧化效果优于0.02％的叔丁基羟基茴香醚(BHA).猪皮胶原多肽具有一定的体外抗氧化作用.     

弹性蛋白酶产生菌的分离鉴定和发酵条件研究

从污水河的土壤中采集样品,分离得到一株产胞外弹性蛋白酶活性较高且稳定的细菌。经初步鉴定属枯草芽孢杆菌(Bacillus subtilis B1),其酶活力为74.25U/ml。对其进行物理诱变,诱变后的菌株(B9)产酶活性有较大的提高。B9酶活力为120.00U/ml,较原菌株提高了1.62倍。同时研究了其产酶最适条件,产酶最适碳源为蔗糖,最适氮源为干酪素,并对碳源、氮源和生长因子进行了正交试验,研究发现氮源对产酶的影响最大。当蔗糖的用量为4%、干酪素为3%、玉米提取液为0.1%时具有较高的产酶水平。最适发酵初始pH为8.0、300ml最适摇瓶装量为40ml、最适接种量为3%。经发酵条件的优化后,B9酶活达到311.54U/ml、提高了2.59倍;较以往国内报道的酶活要高。     

分批与流加发酵法生产纤维素酶的研究

采用里氏木霉ＲｕｔＣ－３０,对２．５Ｌ罐分批和流加发酵产酶条件及优化进行了系统研究。通过研究不同浓度的ＳｏｌｋａＦｌｏｃ（纤维素粉）对分批发酵产酶的影响,发现菌体浓度与产酶量随底物浓度增加而增加,当采用５０ｇ／ＬＳｏｌｋａＦｌｏｃ复合１０ｇ／Ｌ麸皮为碳源时,菌体浓度和产酶量最大,最大ＤＣＷ１３．８２ｇ／Ｌ,ＣＭＣａｓｅ２３４．２Ｕ／ｍｌ,ＦＰＡ２１．２５Ｕ／ｍｌ,但ＳｏｌｋａＦｌｏｃ增加至６０ｇ／Ｌ,高浓度底物对菌体初始生长产生强烈抑制,产酶下降。通过研究不同初始Ｓｏｌ－ｋａＦｌｏｃ浓度对流加发酵产酶的影响,发现当初始底物浓度为５０ｇ／ＬＳｏｌｋａＦｌｏｃ复合１０ｇ／Ｌ麸皮时,菌体量和产酶均达到最大值,分别为ＤＣＷ１５．４１ｇ／Ｌ,ＣＭＣａｓｅ３５９．７Ｕ／ｍｌ,ＦＰＡ３０．６Ｕ／ｍｌ,高菌体量是获得纤维素酶高产的关键因素之一。此外用硫铵盐析法对纤维素酶进行了提取。     

酸枣提取物的抗氧化及抗衰老作用

目的:研究酸枣提取物体外和体内抗氧化及抗衰老作用.方法:对不同质量浓度酸枣提取物(0.05、0.10、0.20、0.40、0.60、0.80、1.00 mg/mL)进行1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除率、羟自由基清除率及Fe3+还原能力测定,评价酸枣提取物体外抗氧化活性;以不同质量分数(0.1％、0...     

海参内脏酶解物和体壁溶出物的护肤功效评价

该研究以海参加工副产物为试验材料,将海参体壁酶解物作为对照,分别考察了海参内脏酶解物和体壁溶出物的保湿、防晒、抗氧化、美白及抗衰老功能,旨在对海参加工副产物的护肤功效进行评价。试验数据表明,内脏酶解物和体壁溶出物在保湿、防晒、抗氧化、抗衰老功能上优于体壁酶解物。其中内脏酶解物的吸湿保湿、抗衰老功能综合评价最佳：在81% RH的12 h吸湿率和保湿率分别为52.51%和95.04%,弹性蛋白酶抑制率达到26.34%;体壁溶出物在防晒、抗氧化功能上表现最佳：在UVC和UVB波段的紫外吸收率分别为94.52%和33.89%,DPPH自由基清除率的IC50为3.00 mg/mL,ABTS与FRAP法总抗氧化能力分别为4.48 mmol/g和5.91 mmol/g。美白功能方面,体壁溶出物及内脏酶解物对酪氨酸酶活性抑制率的IC50分别为49.43 mg/mL和40.00 mg/mL,美白功能低于体壁酶解物（IC50=16.82 mg/mL）,但也能发挥很好的美白作用。在应用中,可以有效利用两种副产物在护肤功效上的作用优势,将二者联合应用或者作为体壁酶解物的补充应用在护肤品上,实现海参加工副产物的高效开发利用。     

Angiotensin I-converting enzyme inhibitory properties of whey protein digests: concentration and characterization of active peptides

The aim of this study was to identify whey-derived peptides with angiotensin I-converting enzyme (ACE) inhibitory activity. The bovine whey proteins alpha-lactalbumin and beta-lactoglobulin were hydrolysed with pepsin, trypsin, chymotrypsin, pancreatin, elastase or carboxypeptidase alone and in combination. The total hydrolysates were fractionated in a two step ultrafiltration process, first with a 30 kDa membrane and then with a 1 kDa membrane. Inhibition of ACE was analysed spectrophotometrically. The peptides were isolated by chromatography and identified by mass and sequencing analysis. The most potent inhibitory peptides were synthesized by the 9-fluorenylmethoxycarbonyl solid phase method. Inhibition of ACE was observed after hydrolysis with trypsin alone, and with an enzyme combination containing pepsin, trypsin and chymotrypsin. Whey protein digests gave a 50% inhibition (IC50) of ACE activity at concentration ranges within 345-1733 micrograms/ml. The IC50 values for the 1-30 kDa fractions ranged from 485 to 1134 micrograms/ml and for the < 1 kDa fraction from 109 to 837 mg/ml. Several ACE-inhibitory peptides were isolated from the hydrolysates by reversed-phase chromatography, and the potencies of the purified peptide fractions had IC50 values of 77-1062 microM. The ACE-inhibitory peptides identified were alpha-lactalbumin fractions (50-52), (99-108) and (104-108) and beta-lactoglobulin fractions (22-25), (32-40), (81-83), (94-100), (106-111) and (142-146).     

Connective tissue and aging

Human skin is composed of epidermal and dermal layers, each of which has its own functional importance. Dermis consist of a fine network of collagen fibers, elastic fibers, and other components of the extracellular matrix (ECM). ECM consist primarily of proteins and complex sugars, which form fibrillar networks and a ground substance. Collagen is an important structural component of skin connective tissue and provides the tensile strength of skin. Approximately 70–80% of the dry weight of skin consists of collagen. The most abundant collagen types in skin are types I and III; the former accounts for 80% of the total collagen content of skin and the latter for approximately 15%. The other collagen types present in skin include type IV collagen, which is abundant in the basement membrane (BM); type V collagen, which is located pericellularly; type VI collagen, which plays a role in matrix assembly and is present as microfibrils between collagen fibers; and type VII collagen, which is a structural component of anchoring fibrils. Elastin accounts for only about 1–2% of the dry weight of skin but is important for the maintenance of skin elasticity and resilience. Glycosaminoglycans are of central importance for the maintenance of a water balance in skin, even though the quantities in ECM are small (0.1–0.3% of the dry weight of skin). In the dermis fibroblasts are responsible for the synthesis of ECM proteins. The fibroblasts in the dermis spend majority of time in quiescent state. However in response to activation, the fibroblasts can be reactivated, and certain pool of cell is able to differentiate into myofibroblasts which have important role in repairing skin defects such as during wound healing. During aging the number of fibroblasts is markedly reduced. Also the response of fibroblasts to various growth factors and mechanical or pathological stimulates (wound healing) is diminished. Skin collagen synthesis declines with aging and as the result of such external factors as long‐term sun exposure and medications, for example, topical corticosteroids. In aging skin, collagen fibers become thicker and less soluble and the synthesis of collagen declines. Skin thickness remains quite constant between 20 and 70 years of age, after which a marked decrease in skin thickness occurs. During aging the expression of collagenases are increased and inhibitors of collagenases are reduced leading to increased proteolysis of connective tissue. Recent studies have shown that collagen synthesis is declined in the skin of heavy smokers, while collagenases are increased inducing premature skin aging. The elastic properties of skin are also affected by aging. Along with increasing age, dermal elastic fibers become thicker and fragmented and oxytalan fibers appear fragmented and shortened. Disintegration of elastic fibers is already seen in a minority of fibers between ages 30 and 70, but the changes become more profound after the age of 70 years, affecting a majority of the fibers. As a result of the decreased number of elastic fibers in aged skin, the elastic recovery of skin decreases in elderly people. Even though the content of GAGs and proteoglycans is relatively small, they have significant role in collagen fibril formation, water content of dermis and in mechanical properties. During aging there are marked alterations in different proteoglycans. The amount and synthesis of versican (high molecular size) is decreased and small molecular size decorin is increased. In photoaged skin versican is increased and is closely associated to elastin while decorin is decreased.     

Elastin structure and its involvement in skin photoageing

Skin aging is a complex process that may be caused by factors that are intrinsic and extrinsic to the body. Ultraviolet (UV) radiation represents one of the main sources of skin damage over the years and characterizes a process known as photoaging. Among the changes that affect cutaneous tissue with age, the loss of elastic properties caused by changes in elastin production, increased degradation and/or processing produces a substantial impact on tissue esthetics and health. The occurrence of solar elastosis is one of the main markers of cutaneous photoaging and is characterized by disorganized and non‐functional deposition of elastic fibers. The occurrence of UV radiation‐induced alternative splicing of the elastin gene, which leads to inadequate synthesis of the proteins required for the correct assembly of elastic fibers, is a potential explanation for this phenomenon. Innovative studies have been fundamental for the elucidation of rarely explored photoaging mechanisms and have enabled the identification of effective therapeutic alternatives such as cosmetic products. This review addresses cutaneous photoaging and the changes that affect elastin in this process.     

两种真菌多糖益生菌酸奶协同抗皮肤衰老的研究

对D-半乳糖致衰老小鼠分别灌胃添加茶新菇多糖或真姬菇多糖的益生菌酸奶,研究两种真菌多糖酸奶对小鼠抗皮肤衰老作用的协同效果。结果显示,皮肤组织经HE染色观察,衰老组小鼠皮肤发生病变,而高剂量组小鼠皮肤修复效果最佳。两种真菌多糖益生菌酸奶均可显著提高小鼠皮肤中SOD活性及含水量,降低MDA含量,提高皮肤和尾腱中HYP含量(p0.05),且与多糖添加量呈剂量增强效应。与衰老组相比,茶新菇多糖酸奶和真姬菇多糖酸奶高剂量组小鼠皮肤中SOD活力提高了66.31%、14.54%,含水率提高16.49%、8.93%,皮肤和尾腱中羟脯氨酸含量分别提高48.27%、65.59%和73.98%、61.63%,MDA含量降低38.96%、45.64%,皮肤抗衰老指标极显著改善(p0.01)。结论:两种真菌多糖均可与益生菌酸奶在皮肤抗衰老方面发挥显著协同作用,有效修复皮肤损伤。     

A novel anti‐ageing mechanism for retinol: induction of dermal elastin synthesis and elastin fibre formation

Dermal elastic fibres are extracellular matrix protein complexes produced by fibroblasts and involved in skin elasticity. Elastin fibres decrease with age as a result of reduced synthesis and increased degradation, resulting in skin sagging and reduced skin elasticity. In this study, we show that retinol (ROL), known to enhance dermal collagen production, is also enhancing elastin fibre formation. ROL induced elastin gene expression and elastin fibre formation in cultured human dermal fibroblasts. Topical treatment of cultured human skin explants with a low dose (0.04%) of ROL increased mRNA and protein levels of tropoelastin and of fibrillin‐1, an elastin accessory protein, as documented by QPCR and immunohistochemistry staining. Luna staining confirmed the increased elastin fibre network in the ROL‐treated skin explants, as compared with untreated controls. These data demonstrate that ROL exerts its anti‐ageing benefits not only via enhanced epidermal proliferation and increased collagen production, but also through an increase in elastin production and assembly.     

地衣芽孢杆菌弹性蛋白酶纯化和性质研究

用地衣芽孢杆菌发酵液制备弹性蛋白酶粗酶液,采用硫酸铵分级沉淀和Sephadex凝胶柱层析的方法分离纯化弹性蛋白酶,并对弹性蛋白酶的酶学性质进行研究。结果表明：弹性蛋白酶粗酶液经40%～70%饱和度的硫酸铵纯化后比活力提高到120U/mg,经凝胶柱层析纯化后比活力可达到292U/mg,纯化倍数为12.6,SDS-PAGE法证实弹性蛋白酶分子质量为29.5kD。对酶学性质的研究结果表明：弹性蛋白酶最适反应温度为55℃,最适反应pH值为7.4,以刚果红-弹性蛋白为底物,米氏常数Km为9.67mg/mL。低浓度金属离子Ca2+和K+对酶活力有促进作用,而Mg2+、Mn2+、Zn2+和Al3+对酶活力则有抑制作用。