New AZT analogues having 5'-alkylsulfonyl groups: synthesis and anti-HIV activity

New derivatives of azidothymidine (AZT) substituted by alkyl and alkylsulphonyl groups at N-3 and C-5', respectively, have been synthesized. The new synthesized derivatives showed remarkable anti-HIV-1 and HIV-2 activity in MT-4 cells. Compounds 8 and 10 have IC(50) values of 0.83 and 0.31 microg/mL against HIV-1 with therapeutic index of 83 and 403, respectively, and IC(50) values of 0.93 and 0.29 microg/mL against HIV-2 with therapeutic index of 74 and 431, respectively. This means that compounds 8 and 10 were cytotoxic to MT-4 cells at CC(50) of 69.2 microg/mL and 125 microg/mL, respectively.     

Trypanocidal and cytotoxic effects of 30 Ethiopian medicinal plants

Trypanocidal and cytotoxic effects of traditionally used medicinal plants of Ethiopia were evaluated. A total of 60 crude plant extracts were prepared from 30 plant species using CH2Cl2 and MeOH. Effect upon cell proliferation by the extracts, for both bloodstream forms of Trypanosoma brucei brucei and human leukaemia HL-60 cells, was assessed using resazurin as vital stain. Of all CH2Cl2 and MeOH extracts evaluated against the trypanosomes, the CH2Cl2 extracts from five plants showed trypanocidal activity with an IC50 value below 20 microg/mL: Dovyalis abyssinica (Flacourtiaceae), IC50 = 1.4 microg/mL; Albizia schimperiana (Fabaceae), IC50 = 7.2 microg/mL; Ocimum urticifolium (Lamiaceae), IC50 = 14.0 microg/mL; Acokanthera schimperi (Apocynaceae), IC50 = 16.6 microg/mL; and Chenopodium ambrosioides (Chenopodiaceae), IC50 = 17.1 microg/mL. A pronounced and selective killing of trypanosomes with minimal toxic effect on human cells was exhibited by Dovyalis abyssinica (CH2Cl2 extract, SI = 125.0; MeOH extract, SI = 57.7) followed by Albizia schimperiana (CH2Cl2 extract, SI = 31.3) and Ocimum urticifolium (MeOH extract, SI = 16.0). In conclusion, the screening of 30 Ethiopian medicinal plants identified three species with good antitrypanosomal activities and low toxicity towards human cells. Dovyalis abyssinica might be a promising candidate for phytotherapy of trypanosomiasis.     

S-Euglobals: biomimetic synthesis, antileishmanial, antimalarial, and antimicrobial activities

Several new euglobal analogues (named as S-euglobals) were synthesized from phloroglucinol via a biomimetic three-component reaction involving Knoevenagel condensation followed by [4+2]-Diels-Alder cycloaddition with monoterpene. Newly synthesized euglobal analogues involve monoterpenes that have not yet been encountered in natural euglobals. S-Euglobals along with previously synthesized robustadial A and B were evaluated for in vitro antileishmanial, antimalarial, antimicrobial, and cytotoxic activities. Out of 16, nine analogues were found to exhibit antileishmanial activity against Leishmania donovani promastigotes. Analogue 7 was the most potent with IC(50) of 2.4 microg/mL and IC(90) of 8 microg/mL, followed by analogues 8 and 11 (IC(50) 5.5 and 9.5 microg/mL). Antileishmanial activity of robustadial A (5) and B (6) was moderate with IC(50) of 20 and 16 microg/mL, respectively. Robustadial A and B and S-euglobal 8 exhibited weak antimalarial activity against Plasmodium falciparum (IC(50) of 2.7-4.76 microg/mL). Few of the euglobal analogues showed antibacterial activity against methicillin-resistant Staphylococcus aureus. Amongst these, analogue 11 was the most potent with IC(50) of 1.0 microg/mL and MIC of 5.0 microg/mL. Most of the compounds were not cytotoxic up to 25 microg/mL in a panel of cell lines consisting of both cancer (SK-MEL, KB, BT-549, and SK-OV-3) as well as non-cancer kidney (Vero and LLC-PK11) cells.     

Synthesis and antitumor activity of cholest-4 alpha-methyl-7-en-3beta-ol derivatives

Cholest-4 alpha-methyl-7-en-3beta-ol (1) has potent inhibitory activity against pc 12 tumor with 0.5043 ratio (10 microg/mL). This paper describes a series of structural modification of this compound, which focus on 3beta-hydroxyl group and 7(8)-double bond. The synthesized derivatives of 1 were tested for human cancer cell lines including colon cancer (HCT-8), liver cancer (BEL-7402) and nasopharyngeal cancer (KB) cells. The results showed that cholest-4 alpha-methyl-8-en-3beta,7 alpha-diol 6a inhibits KB cell significantly with IC(50) 1.32 x 10(-9)microg/mL. In addition, the cytotoxic properties of this compound against HCT-8 and BEL-7402 are excellent with IC(50) 1.2 microg/mL.     

Synthesis and antimycobacterial activity of 7-O-substituted-4-methyl-2H-2-chromenone derivatives vs Mycobacterium tuberculosis

A series of 7-O-alkoxy-4-methylumbelliferone derivatives were prepared using a convenient one step synthesis. Additionally the bromo- and azido derivatives 7-O-(4-bromobutoxy)-, 7-O-(6-bromohexyloxy)- and 7-O-(6-azidohexyloxy)-4-methylumbelliferone derivatives were prepared. In vitro evaluation of antimycobacterial activity determined % inhibition and MIC vs M. tuberculosis H37Rv with toxicity (IC50) assessed in VERO cells. The coumarins with longer alkyl chains (nonyl and decyl) showed the optimum inhibitory activity in this series (MIC 3.13 microg/mL) and IC50 > 10 microg/mL.     

Tyrosinase inhibitory effects and inhibition mechanisms of nobiletin and hesperidin from citrus peel crude extracts

The inhibitory effects of nobiletin and hesperidin from citrus peel crude extracts on tyrosinase diphenolase activity are evaluated. IC50 of nobiletin and hesperidin is 1.49 mM and 16.08mM, respectively and their inhibition mechanism is competitive type with Ki = 2.82 mM and noncompetitive with Ki = 9.16 mM, respectively. Crude extracts from citrus peel (C. unshiu Marc.) were extracted with 95% ethanol and fractionated by petroleum ether (PCPE). The ethanol phase (ECPE) was further desorbed from macroporous adsorption resin (FGRE). Their IC50 values were 8.09 mg/mL, 7.53 mg/mL and 4.80 mg/mL, respectively. Their inhibition on melanogenesis in B16 mouse melanoma cells was also evaluated. FGRE showed a significant inhibition (42.5% at 31.25 microg/mL, p < 0.01) while hesperidin showed almost no inhibition. Nobiletin and PCPE give efficacious antiproliferation effects on B16 mouse melanoma cell with IC50 values 88.6 microM and 62.96 microg/mL, respectively, by the MTT test. Hesperidin and other crude extracts showed very low cytotoxity to the B16 cell.     

Antileishmanial activity, cytotoxicity and QSAR analysis of synthetic dihydrobenzofuran lignans and related benzofurans

A series of synthetic dihydrobenzofuran lignans and related benzofurans were evaluated for their cytotoxicity in a screening panel consisting of various human tumour cell lines, and for their antiprotozoal activity against L. donovani (axenic amastigotes), chloroquine resistant Plasmodium falciparum (strain K1), Trypanosoma brucei rhodesiense and T. cruzi, and for cytotoxicity on L6 cells. No promising cytotoxicities against human tumour cell lines were observed for newly synthesised compounds, but the dimerisation product of some lipophylic esters of caffeic acid, such as compound 2g, showed a high activity against chloroquine-resistant P. falciparum (strain K1) (IC50 0.43 microg/mL) and L. donovani (axenic amastigotes) (IC50 0.12 microg/mL), which was confirmed in an infected macrophage assay (IC50 0.19 microg/mL). QSAR models for the cytotoxic and antileishmanial activity were generated using Quasar receptor surface modelling.     

Oligosaccharides corresponding to the regular sequence of heparin: chemical synthesis and interaction with FGF-2.

It has been proposed that oligosaccharides corresponding to the so-called regular region of heparin/heparan sulfate (HS) bind to fibroblast growth factor-2 (FGF-2). In order to explore the molecular basis of FGF/HS interaction, we describe here the chemical synthesis of a tetra and a hexasaccharide, prepared as methyl glycosides, corresponding to the regular sequence of heparin. The strategy relies on the efficient preparation of three building blocks: a seeding block, an elongating block and a capping block. The hexasaccharide inhibited the binding of FGF-2 on its receptor on human aorta vascular smooth muscle cells with an IC50 value (16+/-1.2 microg/mL) close to that of standard heparin (14.8+/-0.5 microg/mL) whereas the tetrasaccharide was much less potent (IC50 = 127+/-10.5 microg/mL). The hexasaccharide and heparin, inhibited in a dose-dependent manner FGF-2 (30 nM) induced proliferation (IC50 = 23.7+/-1.6 and 30.1+/-1.3 microg/mL, respectively). Under the same experimental conditions, the tetrasaccharide only slightly inhibited the mitogenic effect of FGF-2 (IC50 > 100 microg/mL).     

A potential role of alkaloid extracts from Salsola species (Chenopodiaceae) in the treatment of Alzheimer's disease

From the aerial parts of Salsola oppositofolia, S. soda and S. tragus an alkaloid extract was obtained and tested to evaluate antioxidant and anti-cholinesterase activities. The in vitro study of the antioxidant activity by the DPPH method revealed a significant activity of Salsola alkaloid extracts with IC(50) values ranging from 16.30 microg/mL for S. oppositifolia to 26.17 microg/mL for S. tragus. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities were evaluated. S. tragus alkaloid extract exerted the highest inhibitory activity against AChE (IC(50) of 30.2 microg/mL) and BChE (IC(50) of 26.5 microg/mL). Interestingly, S. soda and S. oppositifolia exhibited a selective inhibitory activity against BChE with IC(50) values of 34.3 microg/mL and 32.7 microg/mL, respectively. Tetrahydroisoquinoline alkaloids were identified and quantified by GC/MS analysis.     

Antileishmanial, antimalarial and antimicrobial activities of the extract and isolated compounds from Austroplenckia populnea (Celastraceae)

Austroplenckia populnea (Celastraceae), known as "marmelinho do campo", is used in Brazilian folk medicine as antimicrobial, anti-inflammatory, and antitumoural agent. The aim of the present work was to evaluate the antimicrobial, antileishmanial and antimalarial activities of the crude hydroalcoholic extract of A. populnea (CHE) and some of its isolated compounds. The phytochemical study of the CHE was carried out affording the isolation of methyl populnoate (1), populnoic acid (2), and stigmast-5-en-3-O-beta-(D-glucopyranoside) (3). This is the first time that the presence of compound 3 in A. populnea is reported. The results showed that the CHE presents antifungal and antibacterial activities, especially against Candida glabrata and Candida albicans, for which the CHE showed IC50 values of 0.7 microg mL(-1) and 5.5 microg mL(-1), respectively, while amphotericin B showed an IC50 value of 0.1 microg mL(-1) against both microorganisms. Compounds 1-3 were inactive against all tested microorganisms. In the antileishmanial activity test against Leishmania donovani, the CHE showed an IC50 value of 52 microg mL(-1), while compounds 2 and 3 displayed an IC50 value of 18 microg mL(-1) In the antimalarial assay against Plasmodium falciparum (D6 and W2 clones), it was observed that all evaluated samples were inactive. In order to compare the effect on the parasites with the toxicity to mammalian cells, the cytotoxicity activity of the isolated compounds was evaluated against Vero cells, showing that all evaluated samples exhibited no cytotoxicity at the maximum dose tested.     

Phytoecdysteroids of Silene guntensis and their in vitro cytotoxic and antioxidant activity

Phytoecdysteroids from aerial parts of Silene guntensis B. Fedtsch were investigated and three phytoecdysteroids were isolated: 2,3-diacetate-22-benzoate-20-hydroxyecdysone (1), 2-deoxy-20-hydroxyecdysone (2), and 20-hydroxyecdysone (3). Their chemical structures were elucidated by DEPT, COSY, 1H and 13C NMR spectroscopy. The isolated compounds 1-3 and crude extracts were evaluated for their antiproliferative and antioxidant activities. They exhibited substantial inhibition of cell growth against human cervix adenocarcinoma (HeLa), hepatocellular carcinoma (HepG-2), and breast adenocarcinoma (MCF-7) cells. The chloroform extract showed potent cytotoxic effects [IC50 values (26.58 +/- 1.88) microg/mL, (20.99 +/- 1.64) microg/mL, and (18.89 +/- 2.36) microg/mL, respectively]. The new compound 1 was mildly cytotoxic compared to extracts [(127.97 +/- 11.34), (106.76 +/- 7.81), and (203.10 +/- 19.56) microg/mL, respectively]. Water and n-butanol extracts exhibited good antioxidant activities [IC50 values of (68.90 +/- 6.45) microg/mL and (69.12 +/- 5.85) microg/mL, respectively].     

Thio-sugars VII. Effect of 3-deoxy-4-S-(beta-D-gluco- and beta-D-galactopyranosyl)-4-thiodisaccharides and their sulfoxides and sulfones on the viability and growth of selected murine and human tumor cell lines

The first conversion of (1-->4)-thiodisaccharides into corresponding sulfoxides and sulfones by conventional oxidation with m-chloroperoxybenzoic acid (MCPBA) is reported. The effects of alpha-(1-->4)-3'-deoxythiodisaccharides (8-9) and their sulfoxide (14-15) and sulfone (16-17) derivatives on murine leukemia and human colon and pancreatic carcinoma cell viability were studied. Concentrations of thio-sugars that decreased tumor cell line viability by 50% (IC(50)), measured via the MTT assay, ranged from 6.4 to 38.3 microg/mL. The effect of alpha-(1-->4)-3'-deoxythiodisaccharide derivatives were most profound on human pancreatic epithelial carcinoma (PANC-1) cells with compounds 8 and 9 having IC(50) values of 6.4 microg/mL and 8.2 microg/mL, respectively. Sulfone derivatives 16 and 17 also had pronounced effects on PANC-1 cell viability (IC(50)=10.2 microg/mL and 9.6 microg/mL, respectively). These results indicate that deoxythio-disaccharide analogs generated by functionalization of the universal chiral precursor levoglucosenone may have cytotoxic properties and therapeutic potential as anticancer agents.     

Design, synthesis, and in vitro photodynamic activities of benzochloroporphyrin derivatives as tumor photosensitizers

Novel benzochloroporphyrin derivatives (BCPDs) were designed, synthesized, and characterized. In vitro dark cytotoxicity and photodynamic efficacy of BCPDs were evaluated by MTT assay on human hepatoma BEL-7402 cells. The experimental results showed that BCPDs 15, 16, 17, and 18 have strong long wavelength absorptions around 670 nm and exhibit significantly lower dark cytotoxicity than BPDMA and possess potent photocytotoxicity, IC50 values 1.32 microg/mL for 15, 0.26 microg/mL for 16, 0.47 microg/mL for 17 of 0.27 microg/mL for 18, and 0.23 microg/mL for BPDMA. Among them, BCPDs 16 and 18 are more effective and promising PDT photosensitizers based on the studies with BEL-7402 cells and show nearly the same photodynamic efficacy as BPDMA. MG-P staining qualitative analysis also indicated that PDT with BCPDs 16 can induce apoptosis in BEL7402 cells.     

美洲商陆抗病毒蛋白-Ⅱ基因的克隆和表达

根据报道的cDNA序列,用RT-PCR的方法从美洲商陆夏季的叶片中克隆美洲商陆抗病毒蛋白-Ⅱ(pokeweedantiviralproteinⅡ,PAP-Ⅱ)基因。将PAP-Ⅱ基因克隆至表达载体pET-28a( )并在大肠杆菌中表达,SDS-PAGE电泳分析结果表明,PAP-Ⅱ蛋白在BL21(DE3)菌中获得表达,表达产物以不溶性包涵体形式存在,经过溶解包涵体、复性和BBSTNTA树脂柱亲和层析纯化,获得高纯度的PAP-Ⅱ蛋白。用非放射性基于ELISA方法检测经过复性纯化后PAP-Ⅱ蛋白和蓖麻毒素A链(RTA)在体外对HIV-1整合酶有较强的抑制活性,其IC50分别约为303μg/mL,220μg/mL。用MTT法分析PAP-Ⅱ蛋白的生物学活性,复性纯化后蛋白对HEP-G2和Hela细胞有细胞毒作用,IC50分别为93μg/mL,102μg/mL,说明了PAP-Ⅱ蛋白能抑制肿瘤细胞的生长。构建的PAP-Ⅱ表达系统所表达的蛋白经复性后具有生物学活性,为进一步研究PAP-Ⅱ的抗HIV-1机制和抗肿瘤作用奠定了基础。     

Neomycin and paromomycin inhibit 30S ribosomal subunit assembly in Staphylococcus aureus

A number of different antibiotics that prevent translation by binding to the 50S ribosomal subunit of bacterial cells have recently been shown to also prevent assembly of this subunit. Antibacterial agents affecting 30S particle activities have not been examined extensively for effects on small subunit formation. The aminoglycoside antibiotics paromomycin and neomycin bind specifically to the 30S ribosomal subunit and inhibit translation. These drugs were examined in Staphylococcus aureus cells to see whether they had a second inhibitory effect on 30S particle assembly. A 3H-uridine pulse and chase assay was used to examine the kinetics of subunit synthesis in the presence and absence of each antibiotic. 30S subunit formation was inhibited by both compounds. At 3 microg/mL each antibiotic reduced the rate of 30S formation by 80% compared with control cells. Both antibiotics showed a concentration-dependent inhibition of particle formation, with a lesser effect on 50S particle formation. For neomycin, the IC50 for 30S particle formation was equal to the IC50 for inhibition of translation. Both antibiotics reduced the viable cell number with an IC50 of 2 microg/mL. They also inhibited protein synthesis in the cells with different IC50 values (2.5 and 1.25 microg/mL). This is the second demonstration of 30S ribosomal subunit-specific antibiotics that prevent assembly of the small subunit.     

雄黄纳米微粒在细胞水平上抑制呼吸道合胞病毒复制的初步研究

建立呼吸道合胞病毒A型(RSV-A型)感染Hep-2细胞模型,通过预防、治疗及直接灭活三种不同给药方式,观察中药雄黄对RSV-A型感染Hep-2细胞病变(CPE)的抑制作用。用高能球磨机研磨双蒸水水飞处理制备雄黄纳米微粒,应用砷钼蓝染色法测定雄黄纳米微粒浓度并在Nano Series粒度测定仪上测定其粒度。以MTT法计算药物的半数中毒剂量(TC50)。通过三种不同给药方式即预防给药、治疗给药及直接灭活给药方式进行体外实验,以利巴韦林为阳性对照药,观察雄黄纳米微粒对RSV-A型感染Hep-2细胞病变所起的作用,并对药物的量效关系进行分析。雄黄纳米微粒TC50值为0.649μg/mL。预防、治疗及直接灭活给药方式均可减轻RSV-A感染Hep-2细胞的CPE程度,其抑制RSV-A型感染Hep-2细胞病变的半数有效浓度(IC50)分别为0.20μg/mL、0.13μg/mL、0.16μg/mL,治疗指数(TI)分别为3.18、4.99和4.11,雄黄纳米微粒对RSV-A型感染Hep-2细胞病变的抑制作用存在着明显的量效关系。雄黄纳米微粒按预防、治疗及直接灭活给药方式给药时,其中治疗给药方式更有利于减轻RSV-A感染Hep-2细胞引起的病变。     

Antimicrobial and cytotoxicity activities of the medicinal plant Primula macrophylla

Primula macrophylla (Primulaceae) is reported as to be useful in asthma, restlessness, insomnia and fish poisoning. Antifungal and toxic activities of crude extract, fractions and a pure isolated compound exhibited statistically significant activities. Excellent antifungal activity was found in the crude extract, benzene and ethyl acetate fractions against T. longifusis and against M. canis with different MIC values. Antileishmanial activity (IC(50) = 50ug/mL) was observed as compared to standard drug Amphotericin B, and cytotoxic activity (LD(50) = 47.919microg/mL) was also found in the chloroform fraction. While pure compound 2-phenylchromone (Flavone) isolated from the chloroform fraction showed good activity (IC(50) = 25microg/mL) against Leishmania and cytotoxicity (LD(50) = 2.0116 microg/mL) in Brine Shrimp experiments. From antileishmanial and cytotoxic activity it can be concluded that 2-phenylchromone is the major compound responsible for these activities.     

Chemopreventive effects of minor dietary constituents in common foods on human cancer cells

Epidemiological evidence has suggested that vegetables and fruits may have a role in cancer prevention. The aim of the present study was to examine the anti-proliferative activity of ten related pure compounds from common vegetables and fruits. Studies were conducted on a series of carcinoma cells derived from eight human organs. The results show that linalool possessed the strongest activity against nine carcinoma cells, and that baicalein and luteolin also exhibited a broad spectrum of anti-proliferative activities. Among them, linalool showed the strongest activity against carcinoma of the cervix (IC50: 0.37 microg/ml), stomach (IC50: 14.1 microg/ml), skin (IC50: 14.9 microg/ml), lung (IC50: 21.5 microg/ml) and bone (IC50: 21.7 microg/ml). As for the flavonoids, luteolin exhibited the strongest activity against carcinoma of the stomach (IC50: 7.1 microg/ml), cervix (IC50: 7.7 microg/ml), lung (IC50: 11.7 microg/ml) and bladder (IC50: 19.5 microg/ml), whereas baicalein possessed the strongest anti-proliferative activity against carcinoma of the cervix (IC50: 9.8 microg/ml), stomach (IC50: 16.1 microg/ml) and skin (IC50: 19.5 microg/ml). The present study indicates that linalool possessed the strongest activity against a broad spectrum of carcinoma cells, especially cervical carcinoma cells, suggesting that linalool and flavonoids are partially responsible for the cancer prevention of common vegetables and fruits.     

Free radical scavenging profile and myeloperoxidase inhibition of extracts from antidiabetic plants: Bauhinia forficata and Cissus sicyoides

There is abundant evidence that reactive oxygen species are implicated in several physiological and pathological processes. To protect biological targets from oxidative damage, antioxidants must react with radicals and other reactive species faster than biological substrates do. The aim of the present study was to determine the in vitro antioxidant activity of aqueous extracts from leaves of Bauhinia forficata Link (Fabaceae-Caesalpinioideae) and Cissus sicyoides L. (Vitaceae) (two medicinal plants used popularly in the control of diabetes mellitus), using several different assay systems, namely, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) decolorization, superoxide anion radical (O2(.-)) scavenging and myeloperoxidase (MPO) activity. In the ABTS assay for total antioxidant activity, B. forficata showed IC50 = 8.00+/-0.07 microg/mL, while C. sicyoides showed IC50 = 13.0+/-0.2 microg/mL. However, the extract of C. sicyoides had a stronger effect on O2(.-) (IC50 = 60.0+/-2.3 microg/mL) than the extract of B. forficata (IC50 = 90.0+/-4.4 microg/mL). B. forficata also had a stronger inhibitory effect on MPO activity, as measured by guaiacol oxidation, than C. sicyoides. These results indicate that aqueous extracts of leaves of B. forficata and C. sicyoides are a potential source of natural antioxidants and may be helpful in the prevention of diabetic complications associated with oxidative stress.     

Biomimetic synthesis, antimicrobial, antileishmanial and antimalarial activities of euglobals and their analogues

In the present communication, naturally occurring phloroglucinol-monoterpene adducts, euglobals G1-G4 (3b/a and 4a/b) and 16 new analogues (13a/b-18a/b and 19-22) were synthesized by biomimetic approach. These synthetic compounds differ from natural euglobals in the nature of monoterpene and acyl functionality. All of these compounds were evaluated for their antibacterial, antifungal, antileishmanial and antimalarial activities. Analogue 17b possessed good antibacterial activity against methicillin-resistant Staphylococcus aureus, while analogues 19-22 possessed potent antifungal activity against Candida glabrata with IC50s ranging from 1.5 to 2.5 microg/mL. Euglobals along with all synthesized analogues exhibited antileishmanial activity. Amongst these, euglobal G2 (3a), G3 (4a) and analogues 13a and 14a showed potent antileishmanial activity with IC50s ranging from 2.8 to 3.9 microg/mL. Analogue 16a possessed antimalarial activity against chloroquine sensitive D6 clone of Plasmodium falciparum. None of the compounds showed toxicity against mammalian kidney fibroblasts (vero cells) upto the concentration of 4.76 microg/ml.