合成脂肪酶的影响

研究了碳源和氮源对白腐菌Sarcodon asparatus合成脂肪酶的影响。橄榄油是脂肪酶合成的最佳碳源，脂肪酶活力达0．65U／mL。蛋白胨、尿素和氯化铵对脂肪酶的合成有促进作用，它们的酶活力分别为0．65、0．67和0．62U／mL，而硫酸铵抑制脂肪酶的合成，其酶活力仅为0．08U／mL。C／N比对细胞生长和酶的合成影响很大，当C／N比从2增加到10时，脂肪酶活力从0．65下降到0．14U／mL，而细胞浓度从3．08升高到4．58mg／mL。在培养基初始pH值5．5、28℃下培养，S．asparatus合成的脂肪酶活力最高，脂肪酶活力和细胞浓度分别为0．65U／mL和3．08mg／mL。     

利用酚试剂测定漆酶活性的比色法

利用酚试剂研究了漆酶活性的比色测定方法。在实验条件下焦性没食子酸氧化产物的吸光值倒数与反应时间的倒数成正比,符合公式1/Q=(b/a)(1/t)+1/a。于是可用上式中a/b来表征漆酶的催化活性。实测数据表明,本法比常规比色法和通气比色法灵敏。     

复合抑制剂对核桃青皮多酚氧化酶活性的影响

为给核桃采摘、生产及加工中褐变现象的抑制提供理论参考依据,从核桃青皮中提取多酚氧化酶(PPO),采用光谱法研究了不同抑制剂及其复合物对其PPO活性的影响情况。单因素试验结果显示:不同抑制剂对核桃青皮PPO酶活性的影响差异明显,亚硫酸钠(Na_2SO_3)、氯化钠(Na Cl)、L-半胱氨酸(L-Cys)、芦丁对核桃青皮PPO活性的最适抑制浓度分别为0.3、0.6、0.3、0.3 mol/L,其中,L-Cys对其PPO活性的抑制效果最为显著。正交试验结果表明:以0.4 mol/L的Na_2SO_3、0.5 mol/L的Na Cl、0.2 mol/L的L-Cys和0.8 mol/L的芦丁配制的复合液对其PPO活性的抑制效果最好。文中综合分析认为,核桃青皮PPO是引起其酶促褐变的主要影响因素,在核桃采摘、生产及加工中可通过添加L-Cys或多种抑制剂的复合物来抑制其PPO活性。     

Insecticidal action of the polyphenolic rich fractions from the stem bark of Streblus asper on Dysdercus cingulatus

Extracts from the stem bark of Streblus asper possess insecticidal activity against the fifth instar of Dysdercus cingulatus. Methanolic extract showed an LC(50) value of 5.56 microg/insect. Partition with chloroform increased the insecticidal activity (LC(50) 2.01 microg/insect). Three polyphenolic rich fractions were obtained from silica-gel column chromatography of the chloroform fraction and found to have noteworthy insecticidal activity (LC(50): 1.82 microg, 2.70 microg, 2.26 microg/insect) by topical application. This may provide a useful beginning for the development of biopesticides.     

Anti-plasmodial activity of Ailanthus excelsa

The anti-plasmodial activity of Ailanthus excelsa stem bark was investigated. The methanolic extract inhibited in vitro growth of chloroquine-sensitive (D10) and resistant strains (W2) of Plasmodium falciparum (IC50 4.6 and 2.8 microg/ml, respectively). The effect was retained in the chloroform fraction (3.1 and 2.1 microg/ml, respectively). The anti-plasmodial activity could be ascribed to the impairment of haemoglobin degradation through the inhibition of plasmepsin II activity (IC50 of 13.43+/-1.74 microg/ml) and of the haem detoxification to haemozoin.     

干旱胁迫对华南地区三种苗木膜脂过氧化及保护酶活性的影响

文章研究了华南石灰岩地区常见植物任豆,以及两种石灰岩地区造林供选树种楝叶吴莱萸、石斑木在干旱胁迫下体内丙二醛（MDA）含量、超氧化物歧化酶（SOD）活性、过氧化物酶（POD）活性的变化,为在石灰岩地区筛选优良的抗旱节水树种提供了科学的理论依据。试验结果表明,三个树种在干旱胁迫下都表现出MDA含量先升高后降低的趋势,其中楝叶吴莱萸在干旱胁迫第9d最先达到峰值（5．08μmol／gFW）,任豆和石斑木第12d达到峰值,分别为4．46和3．35txmol／gFW。苗木SOD活性也都表现出先增大后减小的规律,在中度干旱时期达到峰值,楝叶吴茱萸和任豆的SOD活性在干旱胁迫的第9d达到峰值,分别为384．89和445．07U／g,石斑木SOD活性则在第12d达到峰值517．40U／g。POD活性呈先升高后降低再升高的趋势,石斑木与另两种植物比较,第一个峰值更迟出现,第二个POD活性峰值为1490．24mg·g^-1·min^-1,是三者中最高的。经过对三项指标的综合分析并结合植物的抗旱性表现可知,三个树种中石斑木的适应性较强,抗旱性能较好,其次是任豆,楝叶吴茱萸的抗旱能力较差。     

Bioactive flavonoids from Kaempferia parviflora

Nine flavonoids (1-9) have been isolated from Kaempferia parviflora. Among these, 5,7,4'-trimethoxyflavone (8) and 5,7,3',4'-tetramethoxyflavone (9) exhibited antiplasmodial activity against Plasmodium falciparum, with IC50 values of 3.70 and 4.06 microg/ml, respectively. 3,5,7,4'-Tetramethoxyflavone (7) and compound 8 possessed antifungal activity against Candida albicans with respective IC50 values of 39.71 and 17.63 microg/ml, and also showed mild antimycobacterial activity with the minimum inhibitory concentrations (MIC) of 200 and 50 microg/ml, respectively. However, none of the isolated compounds demonstrated cytotoxicity against KB, BC and NCI-H187 cell lines.     

Antibacterial carbazole alkaloids from Clausena harmandiana twigs

Three new carbazole alkaloids, harmandianamines A-C (1-3), together with fifteen known compounds (4-18) were isolated from the twigs of Clausena harmandiana. The structures were elucidated by spectroscopic methods, including UV, IR, NMR, and MS. The antibacterial activity against Escherichia coli TISTR 780, Salmonella typhimurium TISTR 292, Staphylococcus aureus TISTR 1466 and methicillin-resistant S. aureus (MRSA) SK1 of some isolated compounds was also evaluated. Compound 6 exhibited significant antibacterial activity against MRSA SK1 with an MIC value of 0.25 μg/mL which higher than that of standard drug, vancomycin (MIC value=1 μg/mL) whereas compounds 14 and 5 showed strong activity with MIC values of 4 and 8 μg/mL, respectively. Only compound 14 showed strong antibacterial activity against S. aureus TISTR 1466 with an MIC value of 4 μg/mL.     

甜龙竹不同栽培模式对土壤酶活性的影响及其相关因素分析

在云南省沧源佤族自治县勐甘村的甜龙竹(Dendrocalamus brandisii)基地,采取5种甜龙竹栽培模式：甜龙竹×核桃(ZH)、甜龙竹×西南桦(CK)、甜龙竹×杉木(ZS)、甜龙竹×古茶树(ZC)和甜龙竹×果树(ZG),研究不同栽培模式对土壤酶活性的影响,并分析土壤酶活性与土壤化学性质的相关关系。结果表明：甜龙竹不同栽培模式不同土层对土壤酶活性具有显著影响,不同栽培模式对甜龙竹土壤酶活性的影响排序为：ZS>ZH>ZG>CK>ZC;土壤酶活性随着土层深度的增加呈逐渐下降趋势,说明表层土的微生物生物量聚集的最多,能释放出较多的酶;土壤酶活性与有机质、有机碳、水解氮、有效磷、速效钾、全氮、全磷、全钾存在显著或极显著相关关系。研究认为,在营造和经营甜龙竹林时,选择与杉木共同栽植可以在一定程度上提高土壤中的酶活性,其中对土壤脂肪酶活性的提高最为明显。     

Dual inhibition of cyclooxygenase-1 and 5-lipoxygenase by aerial part of Bupleurum fruticescens methanol extract

The effect of the methanol extract from aerial parts of Bupleurum fruticescens on the release of eicosanoids and hydrolytic enzymes was determined on in vitro cell systems. The extract had a significant effect on 5-lipoxygenase (5-LOX) activity, inhibiting both LTB4 and 5(S)-HETE production with IC50 values of 112 microg/ml and 95 microg/ml, respectively. At concentrations of 200 microg/ml, the extract also inhibited cyclooxygenase-1 (90%) and elastase activities (54%). The 12-LOX activity in intact platelets was not affected; a fact, which suggests that phospholipase A2 (PLA2) activity, is not modified by the extract.     

Hypolipidemic activity of Acorus calamus L. in rats

The rhizomes of Acorus calamus are empirically used in the treatment of a wide variety of human diseases. Administration of the 50% ethanolic extract (100 and 200 mg/kg) as well as saponins (10 mg/kg) isolated from the extract demonstrated significant hypolipidemic activity. On the contrary, the aqueous extract showed hypolipidemic activity only at a dose of 200 mg/kg.     

Antidiarrhoeal activity of Cyperus rotundus

The methanol extract of Cyperus rotundus rhizome, given orally at the doses of 250 and 500 mg/kg b.w., showed significant antidiarrhoeal activity in castor oil induced diarrhoea in mice. Among the fractions, tested at 250 mg/kg, the petroleum ether fraction (PEF) and residual methanol fraction (RMF) were found to retain the activity, the latter being more active as compared to the control. The ethyl acetate fraction (EAF) did not show any antidiarrhoeal activity.     

Antinociceptive diterpene from Euphorbia decipiens

One myrsinol-type diterpene ester (1) isolated from Euphorbia decipiens was evaluated for analgesic activity in the acetic acid induced writhing test in mice. Different dose (5-20 mg/kg i.p.) of the compound showed significant antinociceptive activity, which was comparable to standard analgesic drugs, aspirin and ibuprofen (100 mg/kg i.p.).     

Antiinflammatory activity of Sambucus ebulus hexane extracts

Hexane extracts of aerial parts (flowered browes), leaves and roots of Sambucus ebulus were investigated for their antiinflammatory activity in rats. Aerial parts and roots extracts produced statistically significant and dose dependent inhibition of edema induced by carrageenan at all doses when compared to the control groups. On the contrary, hexane extract of leaves did not show any activity up to 600 mg/kg i.p. The highest activity was showed in the aerial parts and roots that at 600 mg/kg i.p. inhibited inflammation by ca. 80% (78% for diclofenac at 100 mg /kg i.p.). No extracts exhibit toxicity when injected up to 2 g/ kg intraperitoneally in mice.     

TiO_2／SO~（2－）_4催化的α－蒎烯异构化反应

ＴｉＯ＿２／ＳＯ￣（２－）＿４型催化剂对α－蒎烯异构化反应有很高催化活性和较好选择性，主产物是莰烯和三环烯，副产物主要是双戊烯和萜品油烯。文中考察了催化剂制备方法、处理催化剂所用的硫酸和硫酸按溶液的浓度、催化剂的焙烧温度、反应温度及反应时间等因素对催化剂性能的影响，并对催化剂表面性质和催化机理进行了初步探讨。     

四种杨树扦插苗的硝酸还原酶活力体内衰减的初步研究

硝酸还原酶(NADH:NR E.C.1.6.6.1)是植物体内同化硝酸盐的关键酶,可作为作物育种和营养诊断的生化指标。在木本植物方面,硝酸还原酶的研究正在不断向广度和深度发展。     

Phytochemical and antimicrobial investigations of stilbenoids and flavonoids isolated from three species of Combretaceae

The antimicrobial activity and chemistry of the African Combretaceae has been well studied in recent years. The present study aimed to investigate the phytochemistry and antimicrobial activity of lesser known members of this family viz. C. hereroense, C. apiculatum and C. collinum. Pulverized leaves of C. collinum and C. apiculatum, and the fruit of C. hereroense were extracted with organic solvents and subjected to preparative chromatography. Seventeen phenolic constituents including four phenanthrenes from the fruit of C. hereroense and two known bibenzyls (including a combretastatin) from the leaves of C. collinum were isolated. The compounds were then subsequently tested for their antimicrobial activity against Candida albicans, Mycobacterium fortuitum, Staphylococcus aureus, Escherichia coli and Proteus vulgaris. Pinocembrin showed excellent activity against C. albicans (MIC - 6.25 μg/ml), superior to that of the positive control, fluconazole and against S. aureus (MIC - 12.5 mg/ml). The phenanthrenes (compounds 1, 2, 3 and 5) showed some activity against M. fortuitum and S. aureus with a uniform MIC of 25 μg/ml. From this study it was evident that most stilbenoids and flavonoids from the selected Combretaceae have little or no antimicrobial activity.     

Brazilin from Caesalpinia sappan wood as an antiacne agent

In screening experiments for antiacne activity, methanolic and 50% ethanolic extracts of Caesalpinia sappan wood showed the most potent activity out of 28 species of plants extracts. These extracts showed inhibition of Propionibacterium acnes growth, lipase inhibitory activity, and antioxidant activity. In order to isolate the active compound from C. sappan, separation of the extract components was performed by column chromatography and preparative high-performance liquid chromatography (HPLC). Brazilin, protosappanin A, and sappanone B were isolated from methanolic extracts. Brazilin showed better antibacterial activity [minimum inhibitory concentration (MIC) = minimum bactericidal concentration (MBC) = 0.50 mg/ml] than protosappanin A (MIC = MBC = 1.00 mg/ml) and sappanone B (MIC = MBC > 2.00 mg/ml). The 50% inhibitory concentration (IC₅₀) for lipase inhibition was lowest for brazilin (6 μM), which showed strong inhibition compared with protosappanin A (100 μM) and chloramphenicol (677 μM, positive control). The antioxidant activity of brazilin (IC₅₀ 8.8 μM) was not significantly different from protosappanin A (9.1 μM) and (+)-catechin (10.2 μM). The antioxidant activity of brazilin and protosappanin A were higher than sappanone B (IC₅₀ 14.5 μM). Brazilin is considered to have suffi ciently potent activity for use as an antiacne agent.     

Anti-Obesity effects of protopanaxdiol types of Ginsenosides isolated from the leaves of American ginseng (Panax quinquefolius L.) in mice fed with a high-fat diet

Effects of protopanaxdiol (PDG) and protopanaxatriol (PTG) types of ginsenosides isolated from the leaves of American ginseng on porcine pancreatic lipase activity were determined in vitro. PDG inhibited the pancreatic lipase activity in a dose-dependent manner at the concentrations of 0.25–1 mg/ml. It inhibited hydrolysis of about 83.2% of triolein at about 1 mg/ml of PDG. However, PTG showed no inhibitory activity. Therefore, anti-obesity activity of PDG was evaluated in mice fed a high-fat diet. The results demonstrated that PDG was effective in preventing and healing obesity, fatty liver and hypertriglyceridemia in mice fed with a high-fat diet.     

Molluscicidal activity of Aglaia duperreana and the constituents of its twigs and leaves

The methanol (MeOH) extract of the twigs and leaves of Aglaia duperreana was investigated for its molluscicidal activity against Pomacea canaliculata. The extract was found to exhibit significant molluscicidal activity. The ethyl acetate soluble fraction of the extract showed the most potent molluscicidal activity among different solvent fractions. The bioactivity-guided chemical investigation of the ethyl acetate soluble fraction led to a new triterpenoid along with 15 known compounds. Their structures were elucidated by spectroscopic methods, including one- and two-dimensional nuclear magnetic resonance techniques as well as mass spectroscopic analysis. The molluscicidal activities of compounds 2-16 against P. canaliculata were also investigated. Naringenin trimethyl ether showed significant molluscicidal activity with a median lethal concentration (LC(50)) of 3.9 μg/mL, which was indicated higher potency than the positive control, tea saponin (LC(50)=4.5 μg/mL).