A Novel Agarase,Gaa16B,Isolated from the Marine Bacterium Gilvimarinus agarilyticus JEA5, and the Moisturizing Effect of Its Partial Hydrolysis Products

We recently identified a β-agarase, Gaa16B, in the marine bacterium Gilvimarinus agarilyticus JEA5. Gaa16B, belonging to the glycoside hydrolase 16 family of β-agarases, shows less than 70.9% amino acid similarity with previously characterized agarases. Recombinant Gaa16B lacking the carbohydrate-binding region (rGaa16Bc) was overexpressed in Escherichia coli and purified. Activity assays revealed the optimal temperature and pH of rGaa16Bc to be 55 °C and pH 6–7, respectively, and the protein was highly stable at 55 °C for 90 min. Additionally, rGaa16Bc activity was strongly enhanced (2.3-fold) in the presence of 2.5 mM MnCl₂. The K_m and V_max of rGaa16Bc for agarose were 6.4 mg/mL and 953 U/mg, respectively. Thin-layer chromatography analysis revealed that rGaa16Bc can hydrolyze agarose into neoagarotetraose and neoagarobiose. Partial hydrolysis products (PHPs) of rGaa16Bc had an average molecular weight of 88–102 kDa and exhibited > 60% hyaluronidase inhibition activity at a concentration of 1 mg/mL, whereas the completely hydrolyzed product (CHP) showed no hyaluronidase at the same concentration. The biochemical properties of Gaa16B suggest that it could be useful for producing functional neoagaro-oligosaccharides. Additionally, the PHP of rGaa16Bc may be useful in promoting its utilization, which is limited due to the gel strength of agar.     

一个与氰苷生物合成相关的植物CYP基因的克隆与表达分析

氰苷是由植物细胞色素P450单加氧酶(CYP)催化氨基酸生成的次生代谢产物,与植物的防御和抗逆境胁迫相关。为了获得蒜头果中与氰苷生物合成有关的CYP基因,本研究通过分析蒜头果转录组数据,从中分离并克隆得到1条细胞色素P450基因(命名为MoCYP79),并对其进行生物信息学分析及检测该基因在果实不同发育时期的具体表达情况。结果显示,MoCYP79基因的cDNA全长1632 bp,编码543个氨基酸;MoCYP79蛋白含有CYP家族的识别结构域血红素结合域(FSTGRRGC),且与巨桉(XP_010027351.1)、木薯(AAF27290.1,AAF27289.1)等植物CYP79蛋白聚在一支;MoCYP79基因在蒜头果花谢后的果实中表达量呈下降趋势,除发育3个月的果实外,该基因在其余的果实中的表达量均显著高于叶片,从大到小依次为花谢后的果实1个月>2个月>4个月3个月。本实验对研究蒜头果的对病虫害的防御、逆境胁迫的抵御及蒜头果中有效次生代谢产物的发掘具有重要的意义。     

微生物壳聚糖酶的研究概况

壳聚糖是自然界中最丰富的多糖之一.壳聚糖酶能够降解壳聚糖生成壳寡糖,壳寡糖具有多种生物学特性,用途广泛.壳聚糖酶主要分布在微生物和一些植物中,理化性质较稳定.根据其底物特异性和断裂键的专一性可分为Ⅰ、Ⅱ、Ⅲ三类.根据已测序壳聚糖酶的氨基酸序列相似性,壳聚糖酶分别属于糖苷水解酶46号、75号和80号.目前,只有2种壳聚糖酶的3级结构被测定.     

高氰和低氰木薯生氰葡萄糖苷酶Linamarase基因的组织表达差异分析

旨在降低或去除木薯的生氰糖苷,获得安全无毒木薯新品种。本研究以高氰和低氰5 个品种的木薯为材料,通过RT-PCR 方法,研究了生氰葡萄糖苷酶基因Linamarase 在木薯中的表达情况。木薯Linamarase 基因只在地上部分表达;5 个木薯品种,包括低氰和高氰品种,在块根中也均未检测到Linamarase 基因的表达。在地上部分中,顶芽的表达量要远远大于茎和成熟叶片的表达量,而且低氰和高氰品种在顶芽的表达量基本相同,但是低氰品种茎及成熟叶片中Linamarase 的表达量比高氰品种相对较高。木薯生氰糖苷酶Linamarase 在不同木薯品种不同组织的表达情况的不同,可以为筛选安全无毒木薯品种提供一个参考。     

Chemical constituents from Gmelina arborea bark and their antioxidant activity

Gmelina arborea Roxb. is a fast-growing species and is known to have been used in traditional Indian medicine. Chemical constituents from the bark have not been reported, although some chemical constituents from part of this plant (heartwood, leaf, and root) are known. In this study, the bark meal was successively extracted with acetone and methanol. Fractionation of the acetone extract with n-hexane, diethyl ether, and ethyl acetate and subsequent chromatographic separation of the fractions led to the isolation of four compounds. The diethyl ether-soluble fraction yielded tyrosol [2-(4-hydroxyphenyl)ethanol] (1); (+)-balanophonin (2), an 8-5′ neolignan, with opposite optical rotation to known (−)-balanophonin; and gmelinol (3), a known lignan. The ethyl acetate-soluble fraction afforded a new phenylethanoid glycoside to the best of our knowledge, which was identified as (−)-p-hydroxyphenylethyl[5′″-O-(3,4-dimethoxycinnamoyl)-β-d-apiofuranosyl(1′" → 6′)]-β-d-glucopyranoside (4). From the methanol extract, two known compounds, 2,6-dimethoxy-p-benzoquinone (5) and 3,4,5-trimethoxyphenol (6), were isolated and identified. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay of the identifi ed compounds indicated that 3,4,5-trimethoxyphenol (6) exhibited moderate activity. Part of this report was presented at the 57th and 58th Annual Meetings of the Japan Wood Research Society, Hiroshima and Tsukuba, August 2007 and March 2008, respectively     

A new naphthalene glycoside from the roots of Smilax bockii

From the roots of Smilax bockii a new compound, 7-hydroxymethyl-1, 4, 5-trihydroxynaphthalene-4-O-beta-D-xylopyranosyl(1-->6)-beta-D-glucopyranoside, was isolated. The structure of the new compound was elucidated on the basis of spectroscopic methods.     

黔产竹节参总黄酮苷的提取与测定方法研究

［目的］探讨黔产竹节参黄酮苷的提取与检测方法。［方法］以80%乙醇为溶剂,研究了黔竹节参黄酮苷的提取方法,并建立了竹节参黄酮苷的测定方法。［结果］黔产竹节参黄酮苷的提取率为0.981 8%,精制黄酮苷的含量为96.2%;采用分光光度法检测黔产竹节参黄酮苷浓度,对照样品回归方程y=-0.003 00＋0.011 01x,r=0.999 30,对照样品的加标回收率为100.36%。［结论］该方法操作简便快速准确,能满足黔产竹节参中总黄酮苷的提取和检测的要求。     

A new triglucosylated naphthalene glycoside from Aloe vera L.

A new triglucosylated naphthalene derivative, named aloveroside A (1), together with two known anthraquinone dimers and two 6-phenyl-2-pyrone derivatives, was isolated from the Aloe vera ethanolic extracts. The structure of 1 was established as 1-(((4-(1-O-β-D-glucopyranosyl -(1→4)-β-D-xylopyranoside)-hydroxymethyl)-1-hydroxy-8-O-α-L-rhamnopyranoside)naphthalene-2-yl)-ethanone by means of spectroscopic evidences and chemical methods. All these compounds were tested for their BACE inhibitory activity but no significant activities were found.     

Three new phenolic glycosides from Curculigo orchioides G.

Three new phenolic glycosides, curculigosides F–H (1–3), were isolated from rhizomes of Curculigo orchioides Gaertn. Their structures were elucidated based on comprehensive spectroscopic analyses including IR, MS, 1D- and 2D NMR (HSQC, COSY, and HMBC). Curculigosides F–H (1–3) were evaluated for their anti-HBV activity in vitro using the HBV transfected Hep G2.2.15 cell line. Compound 1 exhibited weak activity with an IC₅₀ value of 2.08 mM on hepatitis B virus (HBV) e antigen (HBeAg) secretion of the HepG2.2.15 cell line.     

苦杏仁甙的分离与鉴定

从赤峰地区山杏种仁中分离得到一种氰甙,经核磁共振、红外光谱、元素分析鉴定为苦仁甙。提取方法简便、成本低,产品纯度高。