海洋微藻抗肿瘤及抗氧化活性初筛

目的 对90株海洋微藻的提取物进行了体外抗肿瘤和抗氧化活性筛选,从中寻找活性微藻藻株.方法以细胞凋亡诱导、细胞坏死以及自由基清除为活性指标,采用SRB,TLC自显影技术和DPPH方法进行抗肿瘤以及抗氧化活性筛选,并对活性藻株代谢产物进行了HPLDUV分析.结果与结论发现5株微藻的提取物具有抗肿瘤活性、1株微藻的提取物具有抗氧化活性.HPLC-UV分析表明,其抗氧化活性可能与具有400nm最大紫外吸收的化合物有关.     

Identification of the antibacterial component of an ethanolic extract of the Australian medicinal plant, Eremophila duttonii

Activity-guided fractionation was used to determine the antibacterial component of an ethanolic extract of the leaves of an Australian native medicinal plant, Eremophila duttonii F. Muell. (Myoporaceae). The extract, previously shown to have activity against Gram positive bacteria, was shown to have activity against additional Gram positive bacteria, including Clostridium perfringens, C. sporogenes and Listeria monocytogenes. Thin layer chromatography (TLC) was used to separate the extract into seven coloured fractions in visible light, one of which was shown by bioautography to contain antibacterial activity. Recovery of the component from the TLC plate and testing for antibacterial activity using a plate-hole diffusion assay supported this result. The purity of the component was verified by high-performance liquid chromatography and a time-kill experiment indicated that the purified component showed identical bactericidal activity to the whole extract. TLC spray reagents indicated that the component was a sterol, terpene or sugar but not a flavonoid, while the pigmented nature suggested a carotenoid.     

Antifungal efficacy of ten selected South African plant species against Cryptococcus neoformans

Fungal infections are a major threat to public health care. Cryptococcosis in humans and animals, caused by Cryptococcus neoformans, is a life-threatening disease. In a random antifungal screening of acetone leaf extracts of 400 tree species against Cryptococcus neoformans, the following plant species had good activity: Zanthoxylum capense (Thunb.) Harv. (Rutaceae), Morusmesozygia Stapf (Moraceae), Calodendrum capense (L.f.) Thunb. (Rutaceae), Catha transvaalensis Codd (Celastraceae), Cussonia zuluensis Strey (Araliaceae), Ochna natalitia (Meisn.) Walp. (Ochnaceae), Croton sylvaticus Hochst. ex C. Krauss (Euphorbiaceae), Maytenus undata (Thunb.) Blakelock (Celastraceae), Celtis africana Burm.f. (Ulmaceae), and Cassine aethiopica Thunb. (Celastraceae). Hexane, dichloromethane, acetone, and methanol extracts of these 10 plants were tested against Cryptococcus neoformans using bioautography and microdilution assays. Acetone extracted the highest quantity of plant material. Dichloromethane and hexane extracts of Maytenus undata showed clear bands in bioautography while the other species did not produce good results in bioautography. Maytenus undata extracts had promising antifungal activity against C. neoformans, with average minimum inhibitory concentration (MIC) of 0.09?mg/mL after 24?h and 0.18?mg/mL after 48?h incubation. Croton sylvaticus and Catha transvaalensis extracts also had good activity, with average MIC values of 0.07?mg/mL and 0.09?mg/mL, respectively. Because of the clear bands on bioautograms and low MIC values compared to the other plant species investigated, M. undata was identified as a good candidate for further studies.     

Phytochemical Screening and Antimicrobial Activity of Some Medicinal Plants Against Multi-drug Resistant Bacteria from Clinical Isolates

The in vitro antibacterial activity of various solvents and water extracts of aloe vera, neem, bryophyllum, lemongrass, tulsi, oregano, rosemary and thyme was assessed on 10 multi-drug resistant clinical isolates from both Gram-positive and Gram-negative bacteria and two standard strains including Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922. The zone of inhibition as determined by agar well diffusion method varied with the plant extract, the solvent used for extraction, and the organism tested. Klebsiella pneumoniae 2, Escherichia coli 3 and Staphylococcus aureus 3 were resistant to the plant extracts tested. Moreover, water extracts did not restrain the growth of any tested bacteria. Ethanol and methanol extracts were found to be more potent being capable of exerting significant inhibitory activities against majority of the bacteria investigated. Staphylococcus aureus 1 was the most inhibited bacterial isolate with 24 extracts (60%) inhibiting its growth whereas Escherichia coli 2 exhibited strong resistance being inhibited by only 11 extracts (28%). The results obtained in the agar diffusion plates were in fair correlation with that obtained in the minimum inhibitory concentration tests. The minimum inhibitory concentration of tulsi, oregano, rosemary and aloe vera extracts was found in the range of 1.56-6.25 mg/ml for the multi-drug resistant Staphylococcus aureus isolates tested whereas higher values (6.25-25 mg/ml) were obtained against the multi-drug resistant isolates Klebsiella pneumoniae 1 and Escherichia coli 1 and 2. Qualitative phytochemical analysis demonstrated the presence of tannins and saponins in all plants tested. Thin layer chromatography and bioautography agar overlay assay of ethanol extracts of neem, tulsi and aloe vera indicated flavonoids and tannins as major active compounds against methicillin-resistant Staphylococcus aureus.     

Bioassay-guided isolation of antifungal alkaloids from Melochia odorata

An alkaloidal extract of the leaves of Melochia odorata exhibited antifungal activity against Candida albicans, Cryptococcus neoformans and Saccharomyces cerevisiae using a TLC bioautographic method. Bioassay-guided fractionation of this extract using separation by normal and reverse high-performance liquid chromatography (HPLC) resulted in the isolation of two active compounds identified as frangulanine, a cyclic peptide alkaloid, and waltherione-A, a quinolinone alkaloid.     

Further antibacterial diterpenes from the bark and leaves of Juniperus procera hochst. ex Endl

The bark of Juniperus procera yielded three antibacterial diterpenoids, (+)-E-communic acid (1), (+)-Z-communic acid (2) and (+)-totarol (3). Compound 2 exhibited significant activity against Gram-positive bacteria, while 1 was found to be less active. Compound 3, on the other hand, demonstrated potent activity against Mycobacterium organisms, while its corresponding 3β-hydroxy-derivative 4 was found to be inactive. The chromatographic separation of (+)-Z-communic acid (2) from (+)-E-communic acid (1) and those previously unreported spectral data of 1 and 2 are described. In addition, the leaves yielded (+)-8α-acetoxyelemol, β-peltatin A methyl ether and deoxypodophyllotoxin.     

Bioautography with the Fungus Valsa ceratosperma in the Search for Antimycotic Agents

A simple bioautographic agar spray assay has been developed using the plant pathogenic fungus Valsa ceratosperma as an indicator organism for the detection and activity guided fractionation of antifungal compounds by thin-layer chromatography. Besides silica gel G60 F₂₅₄ aluminium- and glass-backed plates, chemically modified silica gel (RP-18 F_254S, RP-18 WF_254S, RP-8, etc.) plates and various organic solvents were used to evaluate the compatibility of the agar spray technique. Two fungicides, Iprodione (Rovral®) and Mepronil (Bastak®), were tested to determine the sensitivity of the test fungus.     

苦参生物碱和黄酮体外抑菌活性比较

目的 探讨苦参生物碱、黄酮及其单体(苦参碱、氧化苦参碱、苦参酮、槐属二氢黄酮G、5-methyl-Kushenol C、三叶豆紫檀苷和高丽槐素)对不同菌株的体外抑菌作用.方法 采用96孔板微量稀释法测定药物的最小抑菌浓度(MIC);薄层色谱-直接生物自显影法测定药物的抑菌检测限(LOD);纸片扩散法测定苦参黄酮单体的抑菌圈直径大小.结果 苦参总生物碱、总黄酮对金黄色葡萄球菌的MIC值范围分别为4.95～31.64 mg/mL和7.50～31.64 mg/mL,对大肠埃希菌的MIC值范围分别为1～4 mg/mL和1～4 mg/mL.苦参生物碱单体对金黄色葡萄球菌和大肠埃希菌的LOD值均大于10 μg;黄酮单体对金黄色葡萄球菌的LOD值为1.3～2.5 μg,对大肠埃希菌的LOD值小于1.3 μg.各黄酮单体中,槐属二氢黄酮G抑菌作用最强,其次是苦参酮和高丽槐素,三叶豆紫檀苷无抑制作用.结论 对金黄色葡萄球菌和大肠埃希菌,苦参总黄酮及单体的抑菌效果均优于苦参总生物碱及其单体.     

Bioassay-guided isolation of antimicrobial benzopyrans and phloroglucinol derivatives from Hypericum species

Recently the crude methanol extracts of six Hypericum species were analysed against a panel of microorganisms and it was found that H. caprifoliatum Cham. & Schlecht., H. myrianthum Cham. & Schlecht. and H. polyanthemum Klotzsch ex Reichardt were the most active. This paper reports the activity of the hexane, chloroform and methanol fractions of these plants as well as the activity of some isolated compounds against Staphylococcus aureus determined by bioautographic procedures.     

Coumarins from Peucedanum ostruthium. as Inhibitors of Acetylcholinesterase

Abstract

Different plant extracts have been screened by thin-layer chromatography (TLC) bioautography in an effort to discover new acetylcholinesterase (AChE) inhibitors. The CH₂Cl₂ extract of Peucedanum ostruthium. (L.) Koch roots exhibited significant inhibition of AChE -l activity. Active constituents were isolated by bioguided fractionation using almost exclusively centrifugal partition chromatography. Four coumarins (ostruthin, imperatorin, ostruthol, and oxypeucedanin hydrate) and a chromone derivative (peucenin) were found to inhibit AChE activity in this bioassay.