南极海泥来源抗肿瘤真菌的筛选与鉴定

从南极海泥样品中分离得到61株海洋真菌,先采用MTT法对其发酵液的乙酸乙酯萃取物进行体外抗肿瘤活性筛选,然后对活性较高的菌株进行分子鉴定,并进一步测定乙酸乙酯萃取物对HepG-2细胞的IC50值。结果表明:对HepG-2细胞抑制率大于60%的有27株菌,占总供试菌株的44.26%;对7901细胞具有抑制作用的有22株菌,占总供试菌株的36.07%;对116细胞抑制率大于50%的有22株菌,占总供试菌株的36.07%;菌株S45的抗肿瘤活性最强,对HepG-2细胞的IC50值为1.25μg·mL-1,经鉴定为青霉属真菌。     

放线菌IPS-54代谢产物的农用活性

从吉林土样中分离筛选的放线菌IPS-54菌株的代谢产物同时具有杀菌、除草活性。杀菌活性生测结果表明：IPS-54菌株发酵液对烟草赤星病菌、马铃薯干腐病菌、玉米大斑病菌等13种供试病原真菌的菌丝生长抑制率均在80％以上;对枯草芽孢杆菌、大肠杆菌,金黄色葡萄球菌和假丝酵母菌的抑菌圈直径大于20mm;盆栽试验表明对小麦白粉病菌的保护和治疗作用均大于70％,大田防治番茄灰霉病菌的防效在50％以上。除草活性生测结果表明：IPS-54菌株发酵液对反枝苋主茎的抑制率为91．9％,对稗草主茎的抑制率为88．2％。     

放线菌TL05-22菌株发酵液的抑菌谱及稳定性

[目的]研究放线菌TL05-22发酵液的抑菌谱及稳定性。以16种植物病原真菌和6种细菌为供试菌,采用菌丝生长速率法、杯碟法测定拮抗放线菌TL05-22发酵液的抑菌谱;以苜蓿尖镰孢根腐病菌为指示菌,杯碟法测定发酵液的传代稳定性、热稳定性、酸碱稳定性及紫外线稳定性。[结果]放线菌TL05-22发酵液对16种植物病原真菌和6种细菌均具有不同程度的抑菌活性,其中供试真菌以对苜蓿尖镰孢根腐病菌的抑菌效果最好,抑菌圈直径达33.68 mm;供试细菌中以对大白菜软腐病菌的抑菌效果最强,抑菌圈直径达29.12 mm。将发酵液于60~100℃处理30、60 min,抑菌活性没有明显变化;发酵液在pH值6~14时抑菌活性未发生明显变化,但在pH<6条件下抑菌活性明显下降;连续培养10代,发酵液抑菌活性无明显变化。[结论]放线菌TL05-22的代谢产物具有广谱抑菌活性和较强的稳定性,具有一定开发价值。     

56种植物对植物病原菌的生物活性

以小麦赤霉菌等6种常见植物病原真菌为对象,采用生长速率法对56种植物的甲醇提取物进行了室内抑菌活性测定.结果表明:多数供试中草药植物提取物对植物病原真菌都表现出了不同程度的抑菌活性,其中黄连、藁本、臭椿3种植物的甲醇提取物表现出强烈的抑菌活性,对供试的6种病原真菌中的5种生长抑制率都在80%以上,值得深入研究.     

大豆根表拮抗细菌的筛选及其防病作用

从大豆根表分离出20株对植物病原真菌有拮抗作用的细菌,其中4株对供试的6种病原真菌均有抑制作用,对小麦赤霉菌、纹枯菌、黑粉菌、番茄灰霉菌、早疫菌、山芋黑疤病菌的拮抗频率分别为18．8％、18．8％、27．1％、22．9％、29．2％、22．9％。发酵液对小麦赤霉病菌、番茄灰霉菌、早疫病菌孢子萌发均有抑制作用,对上述3种病菌引起的病害田间防效良好。     

防污涂层表面生物膜中防污活性菌株研究

从防污涂层表面生物膜菌落中筛选出具有抑菌活性的5株细菌和1株真菌,并对菌株发酵液和离心后上清液进行了抑藻活性试验,发现真菌Aureobasidium pullulans HN的抑藻效果最为显著,同时发现上清液具有更强的抑藻作用。为寻找天然防污活性物质、研发新型防污技术提供了借鉴。     

8种甲基香豆素衍生物的抑菌及除草活性

[方法]以取代苯酚为起始原料,合成了8种甲基香豆素衍生物.采用菌丝生长速率法和种子萌发法分别测定了合成甲基香豆素衍生物的抑菌及除草活性.[结果]8种甲基香豆素衍生物对4种供试植物病原真菌均有一定抑制作用,4-甲基-7-羟基-8-乙酰基香豆素的活性最强,对棉花枯萎病菌的EC50值为5.31 mg/L,对葡萄白腐病菌的EC50值为13.72 mg/L;8-甲基香豆素对4种供试植物病原菌的EC50.值均小于58 mg/L.8-甲基香豆素除草活性最强,500 mg/L质量浓度下对反枝苋、生菜幼苗根茎生长的抑制率均在75%以上.[结论]8-甲基或乙酰基取代的香豆素的抑菌活性较强,8-甲基香豆素的除草活性较强.     

5种植物精油对植物病原真菌的抑菌活性

[目的]植物精油用作农药具有对人畜安全、对环境友好、生物活性多样等特点,可克服化学农药的局限性,具有开发潜力。研究5种植物精油对10种重要农作物病原真菌的抑菌活性,以期为其在农药领域的开发利用提供依据。[方法]采用生长速率法测定植物精油对病原菌的抑菌活性。[结果]南丰蜜橘精油和胜红蓟精油对供试病原菌表现出较高的抑制活性,精油体积分数为1 mL/L时,对10种植物病原真菌的抑制率分别为77.27%~100%和63.54%~100%。南丰蜜橘精油和胜红蓟精油对10种植物病原真菌菌丝的EC50值分别为0.2316~0.5653、0.0573~0.1943 mL/L。[结论]南丰蜜橘精油和胜红蓟精油对供试植物病原真菌的抑制活性好,具有开发应用前景。     

新型硫色满酮类化合物的合成及体外抗真菌活性

设计合成9种新型硫色满酮吡唑类化合物,并对其抗真菌活性进行初步评价。首先以取代苯硫酚为起始原料,合成中间体3-次苄基硫色满酮;利用苯甲酰肼与3-次苄基硫色满酮在酸性条件反应生成目标化合物。化合物结构通过核磁共振氢谱、质谱等技术进行确认,抗真菌活性实验表明,9种化合物对部分供试真菌有好的活性。硫色满酮吡唑类化合物在体外的抗真菌活性有待进一步研究。     

植物内生真菌抑制细菌活性菌株的筛选

室内以离体方法测试了供试植物内生真菌样品的丙酮提取物对枯草芽孢杆菌、金黄色葡萄球菌、大肠杆菌3种病原细菌抑菌活性，筛选出了对供试细菌有很好离体抑菌效果的植物内生真菌样品，2种是从银杏上分离的内生真菌，1种为扶芳藤上分离的内生真菌。     

Assessment of Tamarindus indica Extracts for Antibacterial Activity

Ethanolic and aqueous (hot and cold) extracts of the fruit pulp, stem bark and leaves of Tamarindus indica were evaluated for antibacterial activity, in vitro, against 13 Gram negative and 5 Gram positive bacterial strains using agar well diffusion and macro broth dilution techniques, simultaneously. The fruit pulp extracts exhibited a wide spectrum of activity; the cold water extract against 95.5% of the test bacterial strains; and the hot water and ethanolic extracts against 90.9% and 86.4%, respectively. In contrast the cold water extract of the leaves and stem bark, each was active against 16.7%; while the ethanolic extract of each was active against 75% of the test strains. The minimum inhibitory concentrations (MIC) ranged from 7.81 mg/mL against Bacillus subtilis ATCC 6051 to 31.25 mg/mL against Escherichia coli ATCC 11775; and the minimum bactericidal concentration (MBC) ranged from 125 mg/mL against Pseudomonas aeruginosa ATCC 10145 to 250 mg/mL against Bacillus subtilis ATCC 6051.     

Antibiotic and Nematocidal Metabolites from Two Lichen Species Collected on the Island of Lampedusa (Sicily)

The antibiotic and nematocidal activities of extracts from two coastal lichen species collected on Lampedusa Island (Sicily), Ramalina implexa Nyl. and Roccella phycopsis Ach., were tested. Methyl orsellinate, orcinol, (+)-montagnetol, and for the first time 4-chlororcinol were isolated from Roccella phycopsis. (+)-Usnic acid was obtained from Ramalina implexa. The crude organic extract of both lichen species showed strong antibiotic activity against some bacterial species and nematocidal activity. Among all the pure metabolites tested against the infective juveniles (J2) of the root-knot nematode (RKN) Meloydogine incognita, (+)-usnic acid, orcinol, and (+)-montagnetol had significant nematocidal activity, comparable with that of the commercial nematocide Velum^® Prime, and thus they showed potential application in agriculture as a biopesticide. On the contrary, methyl orsellinate and 4-chlororcinol had no nematocidal effect. These results suggest that the substituent pattern at ortho-para-position in respect to both hydroxyl groups of resorcine moiety, which is present in all metabolites, seems very important for nematocidal activity. The organic extracts of both lichens were also tested against some Gram-positive and Gram-negative bacteria. Both extracts were active against Gram-positive species. The extract of Ramalina implexa showed, among Gram-negative species, activity against Escherichia coli and Acinetobacter baumannii, while that from Roccella phycopsis was effective towards all test strains, with the exception of Pseudomonas aeruginosa. The antimicrobial activity of (+)-usnic acid, methyl orsellinate, and (+)-montagnetol is already known, so tests were focused on orcinol and 4-chlororcinol. The former showed antibacterial activity against all Gram positive and Gram-negative test strains, with the exception of A. baumannii and K. pneumoniae, while the latter exhibited a potent antibacterial activity against Gram-positive test strains and among Gram-negative strains, was effective against A. baumannii and K. pneumonia. These results suggest, for orcinol and 4-chlororcinol, an interesting antibiotic potential against both Gram-positive and Gram-negative bacterial strains.     

Novel Antibacterial Copolymers Based on Quaternary Ammonium Urethane-Dimethacrylate Analogues and Triethylene Glycol Dimethacrylate

The growing scale of secondary caries and occurrence of antibiotic-resistant bacterial strains require the development of antibacterial dental composites. It can be achieved by the chemical introduction of quaternary ammonium dimethacrylates into dental composites. In this study, physicochemical and antibacterial properties of six novel copolymers consisting of 60 wt. % quaternary ammonium urethane-dimethacrylate analogues (QAUDMA) and 40 wt. % triethylene glycol dimethacrylate (TEGDMA) were investigated. Uncured compositions had suitable refractive index (RI), density (d_m), and glass transition temperature (Tg_m). Copolymers had low polymerization shrinkage (S), high degree of conversion (DC) and high glass transition temperature (Tg_p). They also showed high antibacterial effectiveness against S. aureus and E. coli bacterial strains. It was manifested by the reduction in cell proliferation, decrease in the number of bacteria adhered on their surfaces, and presence of growth inhibition zones. It can be concluded that the copolymerization of bioactive QAUDMAs with TEGDMA provided copolymers with high antibacterial activity and rewarding physicochemical properties.     

Chemical composition, angiotensin I-converting enzyme inhibitory, antioxidant and antimicrobial activities of essential oil of Tunisian Thymus algeriensis Boiss. et Reut. (Lamiaceae)

The present study describes chemical composition, angiotensin I-converting enzyme (ACE) inhibitory, antioxidant and antimicrobial activities of the essential oil of wild growing Thymus algeriensis Boiss. et Reut. (Lamiaceae), a traditional medicinal plant which is mainly endemic in Tunisia and Algeria. The essential oil from the fresh leaves and flowers of T. algeriensis were extracted by hydrodistillation and analysed by GC and GC/MS. Fifty-seven compounds were identified accounting for 97.71% of the total oil, where oxygenated monoterpenes constituted the main chemical class (44.85%). The oil was dominated by camphor (7.82%), 4-terpineol (7.36%), α-pinene (6.75%), 1,8-cineole (5.54%) and cis-sabinene hydrate (5.29%). The T. algeriensis essential oil was found to possess an interesting inhibitory activity towards ACE with an IC50 value of 150 μg/ml. The obtained results also showed that this oil can act as radical scavengers (IC₅₀ = 0.8 mg/ml) and displayed a lipid peroxidation inhibitory activity (IC₅₀ = 0.5 mg/ml) as evaluated by 2,2-diphenyl-1-picrylhydrazyl and β-carotene bleaching methods, respectively. Furthermore, the oil was tested for antimicrobial activity against six bacterial strains and two fungal strains. The inhibition zones and minimal inhibitory concentration values of microbial strains were in the range of 13.5-64 mm and 1-6 μl/ml, respectively. The oil exhibited remarkable inhibitory activity against fungal and Gram-positive bacteria strains.     

Synthesis and Properties of Dicephalic Cationic Surfactants Containing a Quaternary Ammonium and a Guanidine Group

Novel dicephalic surfactants containing a quaternary ammonium and a guanidine group were synthesized, and the effect of the alkyl chain length on micellization and antimicrobial activity were investigated. Surface tension and conductivity were applied to study the self-aggregation of the amphiphilic molecule in aqueous solution. The results indicated that these compounds reduce the surface tension to a level of 30–36 mN/m at the air/water interface and that there is a characteristic chain length dependence of the micellization process of surfactants. The antimicrobial activity was evaluated against Gram-negative, Gram-positive bacteria and fungi, indicating strong antibacterial activity against tested strains.     

苦参愈伤组织诱导及其杀虫抑菌生物活性测定

通过以苦参越冬芽、茎、子叶和幼叶为外植体诱导愈伤组织,四者在合适的培养基上均能诱导出愈伤组织,幼叶和子叶易于诱导愈伤组织。苦参叶和子叶诱导的愈伤组织处理淡色库蚊的死亡率为100％,处理桃蚜的死亡率分别为81．01％和85．42％,高于其他愈伤组织的活性;各愈伤组织处理朱砂叶螨的死亡率均达到了95％以上,与种子提取物的活性没有显著差异。只有子叶诱导的愈伤组织对油菜菌核病菌表现出了抑制作用,各愈伤组织对小麦赤霉病菌和黄瓜灰霉病菌均未表现出明显的活性,显著低于苦参种子提取物的活性。     

保护地蚜虫杀虫真菌的分离及毒力测定初报

从不同地方共采集到上百只被真菌侵染死亡的昆虫,通过分离纯化共得到82株虫生真菌。以保护地发生严重的桃蚜为试虫,选出其中15株生长快、产孢多的菌株进行毒力测定,结果表明这15株真菌对蚜虫均有致病性,但不同菌株对蚜虫的致病力存在明显差异。致病力最强的10号和9号菌株,在1.2×109个孢子/mL下,对蚜虫的校正死亡率高达76.6%和72.6%。     

Antifungal Activity of N-(4-Halobenzyl)amides against Candida spp. and Molecular Modeling Studies

Fungal infections remain a high-incidence worldwide health problem that is aggravated by limited therapeutic options and the emergence of drug-resistant strains. Cinnamic and benzoic acid amides have previously shown bioactivity against different species belonging to the Candida genus. Here, 20 cinnamic and benzoic acid amides were synthesized and tested for inhibition of C. krusei ATCC 14243 and C. parapsilosis ATCC 22019. Five compounds inhibited the Candida strains tested, with compound 16 (MIC = 7.8 µg/mL) producing stronger antifungal activity than fluconazole (MIC = 16 µg/mL) against C. krusei ATCC 14243. It was also tested against eight Candida strains, including five clinical strains resistant to fluconazole, and showed an inhibitory effect against all strains tested (MIC = 85.3–341.3 µg/mL). The MIC value against C. krusei ATCC 6258 was 85.3 mcg/mL, while against C. krusei ATCC 14243, it was 10.9 times smaller. This strain had greater sensitivity to the antifungal action of compound 16. The inhibition of C. krusei ATCC 14243 and C. parapsilosis ATCC 22019 was also achieved by compounds 2, 9, 12, 14 and 15. Computational experiments combining target fishing, molecular docking and molecular dynamics simulations were performed to study the potential mechanism of action of compound 16 against C. krusei. From these, a multi-target mechanism of action is proposed for this compound that involves proteins related to critical cellular processes such as the redox balance, kinases-mediated signaling, protein folding and cell wall synthesis. The modeling results might guide future experiments focusing on the wet-lab investigation of the mechanism of action of this series of compounds, as well as on the optimization of their inhibitory potency.     

Synthesis and Characterization of Cationic Surfactants Based on N‐Hexamethylenetetramine as Active Microfouling Agents

Four cationic surfactants of quaternary hexammonium silane chloride based on hexamethylenetetramine and alkyl chloride were synthesized. The chemical structures of the prepared cationic surfactants were elucidated using Fourier transform infrared (FT‐IR) spectroscopy and mass spectrometry analysis. The surface and thermodynamic properties of the prepared surfactants were also studied. The performance of these cationic surfactants as microfouling agents against two strains of Gram‐negative bacteria, namely, Pseudomonas aeruginosa and Escherichia coli, and two strains of Gram‐positive bacteria, namely, Staphylococcus aureus and Bacillus subtilis, were evaluated as antimicrobial agents. The results showed that the maximum antimicrobial activity was detected for N‐hexamethylenetetramine‐N‐ethyl silane ammonium trichloride (Ah). The maximum and minimum antimicrobial activities were 73 and 60 % against S. aureus and E. coli, respectively, at a concentration of 5 mg/l, pH 7, and 37 °C.     

Aqueous and Organic Solvent-Extracts of Selected South African Medicinal Plants Possess Antimicrobial Activity against Drug-Resistant Strains of Helicobacter pylori: Inhibitory and Bactericidal Potential

The aim of this study was to identify sources of cheap starting materials for the synthesis of new drugs against Helicobacter pylori. Solvent-extracts of selected medicinal plants; Combretum molle, Sclerocarya birrea, Garcinia kola, Alepidea amatymbica and a single Strychnos species were investigated against 30 clinical strains of H. pylori alongside a reference control strain (NCTC 11638) using standard microbiological techniques. Metronidazole and amoxicillin were included in these experiments as positive control antibiotics. All the plants demonstrated anti-H. pylori activity with zone diameters of inhibition between 0 and 38 mm and 50% minimum inhibitory concentration (MIC(50)) values ranging from 0.06 to 5.0 mg/mL. MIC(50) values for amoxicillin and metronidazole ranged from 0.001 to 0.63 mg/mL and 0.004 to 5.0 mg/mL respectively. The acetone extracts of C. molle and S. birrea exhibited a remarkable bactericidal activity against H. pylori killing more than 50% of the strains within 18 h at 4× MIC and complete elimination of the organisms within 24 h. Their antimicrobial activity was comparable to the control antibiotics. However, the activity of the ethanol extract of G. kola was lower than amoxicillin (P < 0.05) as opposed to metronidazole (P > 0.05). These results demonstrate that S. birrea, C. molle and G. kola may represent good sources of compounds with anti-H. pylori activity.