Evaluation of Turkish seaweeds for antiprotozoal, antimycobacterial and cytotoxic activities

As part of our continuing research on seaweeds, crude MeOH extracts of two green, three brown and six red algae collected from Marmara, Black, Aegean and Mediterranean Seas were screened. Four parasitic protozoa, i.e. Plasmodium falciparum, Trypanosoma brucei rhodesiense, T. cruzi, Leishmania donovani and the tubercle bacillus Mycobacterium tuberculosis were used as test organisms for the in vitro assays. The selective toxicity of the extracts was also determined against mammalian L6 cells. All seaweed extracts were active against T. brucei rhodesiense; the Dasya pedicellata extract was the most potent (IC₅₀ value 0.37 µg/mL). The same extract also weakly inhibited the growth of T. cruzi (IC₅₀ 62.02 µg/mL). All seaweed extracts also showed leishmanicidal activity (IC₅₀ values 16.76–69.98 µg/mL). The majority of the extracts also exhibited antiplasmodial potential and the most potent extracts were those from D. pedicellata (IC₅₀ 0.38 µg/mL), Codium bursa (IC₅₀ 1.38 µg/mL) and Caulerpa rasemosa (IC₅₀ 3.12 µg/mL). One brown and two red algal extracts showed some weak activity against Mycobacterium tuberculosis (MIC values 125–256 µg/mL). Except for the extract of Dasya pedicellata, none of the extracts displayed any cytotoxicity. This is the second study investigating the antiprotozoal activities of Turkish marine algae and identifies Dasya pedicellata, an understudied algal species, as a candidate for further studies. Copyright © 2010 John Wiley & Sons, Ltd.     

养颜青娥丸对小鼠B-16黑素瘤细胞株黑素合成和酪氨酸酶的影响

 目的：研究养颜青娥丸对小鼠B-16黑素瘤细胞株细胞增殖、黑素合成的影响及对细胞内酪氨酸酶的影响。 方法：四甲基偶氮唑蓝（MTT）比色法测定养颜青娥丸对细胞增殖的影响；酶学方法研究养颜青娥丸对酪氨酸酶活性的作用；470 nm比色法测定合成黑素含量A值。结果：研究发现养颜青娥丸对黑素细胞增殖及酪氨酸酶活性有抑制作用，对合成黑素含量有降低作用；组方单味药中杜仲、沙苑子、制首乌对黑素细胞增殖及酪氨酸酶活性有抑制作用，对合成黑素含量有降低作用；补骨脂、核桃肉对黑素细胞增殖及酪氨酸酶活性有促进作用，对合成黑素含量有增加作用。结论：养颜青娥丸对黄褐斑可能有一定的治疗作用，但治疗机制不能单纯用生化学、酶学改变来解释。     

阿朴菲类生物碱抗癌活性研究进展

阿朴菲类生物碱是一类重要的天然产物,其抗癌活性是近几年药学研究的热点。查阅国内外相关文献,总结阿朴菲类生物碱抗癌活性的基本构效关系、抗癌活性及其作用机制。1,2-亚甲二氧基及N-甲基取代对于该类化合物的细胞毒活性较关键,C-7的氧化和脱氢有助于提高该类化合物的抗癌活性,C-6a的手性及其他位置取代基对于抗癌活性的贡献目前尚未明确。阿朴菲类生物碱主要通过诱导细胞凋亡、抑制细胞增殖以及抑制DNA拓扑异构酶机制发挥抗癌作用。     

Effects of cuminaldehyde on melanoma cells

Cuminaldehyde (4-isopropylbenzaldehyde) suppressed melanin formation in cultured murine B16-F10 melanoma cells in a dose-dependent decrease up to 0.25 mm without affecting cell growth. Approximately 30% suppression in melanin production resulted when the cells were cultured with 0.25 mm of cuminaldehyde. This activity was not noticeable with cultured human A375 melanoma cells.     

(+)-Tiliarine,a selective in vitro inhibitor of human melanoma cells

Five diphenylbisbenzylisoquinoline (DBBI) alkaloids, tiliacorinine, tiliacorine, nor- tiliacorinine A, tiliarine and tiliamosine were isolated from the ethanol extract of the roots of Tiliacora racemosa Colebr. and identified by spectral techniques. Of these (+)-tiliarine is the only one which exhibited a selective inhibitory effect against human melanoma cells (G 361) and had no activity on normal human fibroblasts (CCD 974 SK). The activity of (+)-tiliarine against the human melanoma cell line was not much modified in the presence of calcium chloride.     

Isocordoin analogues promote apoptosis in human melanoma cells via Hsp70

Isocordin 1 and a series of 4‐oxyalkyl‐isocordoin analogues 2 – 8 were evaluated for their cytotoxicity effect against human melanoma cells (A2058). Analogues 4 , 5 , and 6 showed a higher inhibitory activity with IC₅₀ values of 12.91 ± 0.031, 24.88 ± 0.013, and 11.62 ± 0.017, respectively. These analogues, 4 , 5 , and 6 , also induced an apoptotic response at 12.5‐ and 25‐μM concentrations. They inhibited the expression of antiapoptotic proteins Bcl‐2 and Hsp70, a critical factor that promotes tumour cell survival. In contrast, Bax and caspase‐9 expression, and caspase‐3 enzyme resulted activated. These results were correlated to a DNA fragmentation typical of apoptosis and an increase of intracellular reactive oxygen species (ROS) levels. Alternatively, at higher concentration (50 μM), when the capacity of the cells to sustain Hsp70 synthesis is reduced, our results seem to indicate that necrosis was induced by a further increase in ROS production. Therefore, the central finding in the present study is that these molecules downregulates Hsp70 expression. Altogether, these results suggest that 4‐oxyalkyl‐isocordoin analogues 4 , 5 , and 6 deserve to be deeply investigated for a possible application as Hsp70 inhibitor in the management of melanoma.     

Cranberry proanthocyanidins are cytotoxic to human cancer cells and sensitize platinum‐resistant ovarian cancer cells to paraplatin

Polyphenolic extracts of the principal flavonoid classes present in cranberry were screened in vitro for cytotoxicity against solid tumor cells lines, identifying two fractions composed principally of proanthocyanidins (PACs) with potential anticancer activity. Matrix‐Assisted Laser Desorption/Ionization Time‐Of‐Flight Mass Spectrometry (MALDI‐TOF‐MS) analysis of the proanthocyanidins (PACs) fractions indicated the presence of A‐type PACs with 1–4 linkages containing between 2–8 epicatechin units with a maximum of 1 epigallocatechin unit. PACs exhibited in vitro cytotoxicity against platinum‐resistant human ovarian, neuroblastoma and prostate cancer cell lines (IC₅₀ = 79–479 µg/mL) but were non‐cytotoxic to lung fibroblast cells (IC₅₀ > 1000 µg/ml). SKOV‐3 ovarian cancer cells treated with PACs exhibited classic apoptotic changes. PACs acted synergistically with paraplatin in SKOV‐3 cells. Pretreatment of SKOV‐3 cells with PACs (106 µg/ml) resulted in a significant reduction of the paraplatin IC₅₀ value. Similarly, in a BrdU incorporation assay, co‐treatment of SKOV‐3 cells with PACs and paraplatin revealed reduced cell proliferation at lower concentrations than with either individually. In SKOV‐3 cell cultures co‐treated with PAC‐1 and paraplatin, an HPLC analysis indicated differential quantitative presence of various PAC oligomers such as DP‐8, ‐9, ‐11 and ‐14 indicating either selective binding or uptake. Cranberry proanthocyanidins exhibit cell‐line specific cytotoxicity, induce apoptotic markers and augment cytotoxicity of paraplatin in platinum‐resistant SKOV‐3 ovarian cancer cells. Copyright © 2009 John Wiley & Sons, Ltd.     

花旗松素对人宫颈癌Hela细胞的体外抗肿瘤活性及其机理研究

目的观察和探索花旗松素对人宫颈癌Hela细胞的体外抗肿瘤活性及其作用机理。方法结晶紫染色法检测花旗松素对人宫颈癌Hela细胞的增殖抑制作用;RT-PCR法检测与肿瘤细胞凋亡相关基因的表达。结果花旗松素能够抑制人宫颈癌Hela细胞的增殖,呈剂量依赖关系;花旗松素不能诱导Bcl-2 mRNA和Bax mRNA的表达,但能使P53和P21的mRNA表达量增加。结论花旗松素具有良好的体外抑制人宫颈癌Hela细胞增殖作用;花旗松素诱导Hela细胞死亡与细胞凋亡相关,其分子机制可能与升高P53和P21mRNA表达有关,而与Bcl-2和Bax的蛋白转录无关。     

冬凌草甲素对人黑色素瘤A375细胞侵袭和转移的影响及机制研究

目的研究冬凌草甲素对人黑色素瘤A375细胞侵袭和转移的抑制作用及其作用机制。方法采用细胞培养技术体外培养A375细胞,用不同浓度冬凌草甲素处理细胞,采用CCK-8法检测细胞增殖率;划痕实验分析细胞的迁移能力;Transwell小室实验研究细胞的侵袭能力;黏附实验评价细胞的黏附能力;Western blotting法检测转录因子Snail、E-钙黏蛋白(E-cadherin)、N-钙黏蛋白(N-cadherin)、波形蛋白(vimentin)、基质金属蛋白酶-2(MMP-2)和MMP-9蛋白的表达。结果冬凌草甲素对A375细胞48 h半数抑制浓度(IC50)为47.94μmol/L;与对照组比较,5、10、20μmol/L冬凌草甲素可明显降低A375细胞的体外迁移、侵袭及黏附能力(P0.05),且具有量效关系。冬凌草甲素作用于细胞后,E-cadherin蛋白表达水平明显上调(P0.05),Snail、N-cadherin、vimentin、MMP-2和MMP-9蛋白表达水平明显下调(P0.05)。结论冬凌草甲素具有体外抑制A375细胞侵袭和转移的作用,其机制可能与调控上皮-间质转化(EMT)及MMPs有关。     

In vivo and in vitro studies on the anticancer activity of Copaifera multijuga hayne and its fractions

Copaiba oil resin (COR) obtained from Copaifera multijuga Hayne has been used in popular medicine as an antinflammatory and for the treatment of bronchitis, ulcers and cancer. The aim of this study was to evaluate the action of COR and its fractions on the inhibition of lung metastasis and tumour growth induced by B16F10 melanoma cells in mice and cytotoxicity in vitro using Trypan Blue exclusion method and MTT conversion.Mice which have received subcutaneously B16F10 cells developed a solid tumour that reached a peak at 17 days. Together with the increase in tumour growth we also observed an increase in the number of lung nodules. There was a positive correlation between the in vitro cytotoxic assay and in vivo antitumour activity. The oral administration of COR (at 2 g/Kg in the days 3, 5, 7, 10, 12 and 14 after inoculation of tumoral cells) reduced tumour growth by 58% and tumour weight by 76%. At the same dose COR reduced the number of lung nodules by 47.1%. In vitro experiments showed that COR incubated with the melanoma cell line reduced cell viability in a concentration and time-dependent manner. Diterpenic and sesquiterpenic fractions or reconstituted oil induced cytotoxicity. Our results shows that COR and its fractions have tumouricidal activity in the melanoma cell line in both models in vivo and in vitro.     

Cytotoxic activity of alkaloids isolated from Stephania rotunda in vitro cytotoxic activity of cepharanthine

Three major alkaloids: cepharanthine (1), tetrahydropalmatine (2) and xylopinine (3) isolated from Stephania rotunda tuber were investigated for their cytotoxic activity in a panel of human cancer cells (HT29, LS174T, SW620 and HepG2) using MTT assay. In the present study, cepharanthine (1) exerted potent cytotoxicity against colon and hepatoma cancer cell lines with IC₅₀ values between 2.4 and 5.3 µM while tetrahydropalmatine (2) and xylopinine (3) displayed weak cytotoxicity. In addition, the mutagenic activity of cepharanthine (1) was investigated using a modified liquid incubation technique of the Salmonella/microsomal assay. This alkaloid (1) was found to be non‐mutagenic for doses up to 8.2 µM. Copyright © 2008 John Wiley & Sons, Ltd.     

Cytotoxic activity of Brazilian Cerrado plants used in traditional medicine against cancer cell lines

The search for new anti-cancer drugs is one of the most prominent research areas of natural products. Numerous active compounds isolated from Brazilian Cerrado plant species have been studied with promising results.     

Brazilian red propolis exerts a cytotoxic action against prostate cancer cells and upregulates human monocyte functions

Different propolis samples can be obtained in Brazil, such as green, brown and red. Studies related to Brazilian red propolis (BRP) have increased in the last few years, so the aim of this study was to investigate its effects on the prostate cell lines LNCaP and PC-3 and on human monocytes. BRP chemical composition was analyzed by HPLC-DAD, the viability of monocyte and cancer cell by MTT assay. Cytokine production (TNF-α, IL-1β, IL-6, IL-10) by monocytes was quantitated by ELISA, the expression of cell markers (TLR-2, TLR-4, HLA-DR, CD80) and reactive oxygen species by flow cytometry. The candidacidal activity and the effects of supernatant of treated monocytes on tumor cells were assessed. BRP affected LNCaP viability after 48 and 72 h, while PC-3 cells were more resistant over time. BRP upregulated CD80 and HLA-DR expression, and stimulated TNF-α, IL-6 and IL-10 production. BRP enhanced the fungicidal activity of monocytes, displayed an antioxidant action and the supernatant of BRP-treated monocytes diminished LNCaP viability. In the search for new immunomodulatory and antitumoral agents, BRP exerted a selective cytotoxic activity on prostate cancer cells and an immunomodulatory action, suggesting its potential for clinical trials with oncological patients and for the discovery of new immunomodulatory and antitumor drugs.     

Inhibitory effects of Sargassum polycystum on tyrosinase activity and melanin formation in B16F10 murine melanoma cells

Ethnopharmacological relevance

Sargassum polycystum, a type of brown seaweed, has been used for the treatment of skin-related disorders in traditional medicine.

Aim of the study

The aim of the present study is to investigate the antimelanogenesis effect of Sargassum polycystum extracts by cell-free mushroom tyrosinase assay followed by cell viability assay, cellular tyrosinase assay and melanin content assay using B16F10 murine melanoma cells.

Materials and methods

Sargassum polycystum was extracted with 95% ethanol and further fractionated with hexane, ethyl acetate and water. The ethanolic crude extract and its fractionated extracts were tested for their potential to act as antimelanogenesis or skin-whitening agents by their abilities to inhibit tyrosinase activity in the cell-free mushroom tyrosinase assay and cellular tyrosinase derived from melanin-forming B16F10 murine melanoma cells. The tyrosinase inhibitory activity was correlated to the inhibition of melanin production in α-MSH-stimulated and unstimulated B16F10 cells.

Results

Sargassum polycystum ethanolic extract and its fractions had little or no inhibitory effect on mushroom tyrosinase activity. However, when tested on cellular tyrosinase, the ethanolic extract and its non-polar fraction, hexane fraction (SPHF), showed significant inhibition of cellular tyrosinase activity. In parallel to its cellular tyrosinase inhibitory activity, SPHF was also able to inhibit basal and α-MSH-stimulated melanin production in B16F10 cells.

Conclusions

Our findings showed that (i) cellular tyrosinase assay is more reliable than mushroom tyrosinase assay in the initial testing of potential antimelanogenesis agents and, (ii) SPHF inhibited melanogenesis by inhibiting cellular tyrosinase activity. SPHF may be useful for treating hyperpigmentation and as a skin-whitening agent in cosmetics industry.     

Comparative study on the cytotoxic effect of viscotoxin and mistletoe lectin on tumour cells in culture

A comparative study was carried out on the effect of viscotoxin and mistletoe lectin I, two mistletoe proteins known to be toxic to mammals, on three tumour cell lines in culture (Yoshida sarcoma cells, T-cell leukaemia cells Molt4, and myeloid cells K562). Both viscotoxin and mistletoe lectin were cytotoxic for the three cell lines tested, although the cell sensitivity was dependent on the type of cells used. Yoshida cells were the most sensitive to viscotoxin (ED₅₀ = 0.7 μg/mL) and less sensitive to mistletoe lectin (ED₅₀ = 12.8 μg/mL). K562 cells were more sensitive to mistletoe lectin (ED₅₀ = 75 pg/mL) than Molt4 cells (ED₅₀ = 1.3 ng/mL), whose high sensitivity to mistletoe lectin is well known. Data are also reported showing that this cell line dependent sensitivity can be exploited to demonstrate and/or to discriminate the toxic activities of either substances in crude mistletoe extracts. In particular the Yoshida cell line can represent a suitable system for a bioassay of viscotoxin in these extracts.     

Alpha-hederin potentiates 5-FU antitumor activity in human colon adenocarcinoma cells

The aim of this study was to investigate the ability of alpha-hederin to improve the efficacy of widely prescribed 5-fluorouracil (5-FU) in a human colon adenocarcinoma model. Drug combinations of alpha-hederin and 5-FU using both fixed-concentration and combination index methods were performed in vitro in HT-29 cells. The results showed that alpha-hederin at sub-IC(50) cytotoxic concentrations enhanced 5-FU cytotoxicity about 3.3-fold (p < 0.001). Simultaneous combination of alpha-hederin and 5-FU at their IC(50) ratio showed either a synergistic effect at a moderate cytotoxic range (25% of cell growth inhibition) or an antagonistic effect at a high level of growth inhibition. The data indicate therefore that it is possible to optimize colorectal cancer cell sensitivity to 5-FU with alpha-hederin.     

Potent in vitro cytotoxic and antioxidant activity of Careya arborea bark extracts

Careya arborea is used in traditional medicine for the treatment of tumors and other ailments. The successive chloroform and ethyl acetate extracts and crude 50% methanol extract exhibited potent cytotoxicity against cancerous RD, HEp-2 and HeLa cell lines. They were found to be safe against the normal Vero cell line. The methanol and aqueous extracts possessed strong antioxidant activity against many oxidants in the in vitro antioxidant screening. The total phenol content of these extracts was found to be high. The results suggest strong cytotoxic and antioxidant properties and support the ethnomedical claims for the plant.     

Study of the antioedema activity of some seaweed and sponge extracts from the mediterranean coast in mice

Chloroform and methanol extracts of ten marine species, seven seaweeds and three sponges, have been studied for possible, antioedema activities. The extracts were administered either topically or orally on TPA-induced mouse ear oedema and on carrageenan mouse paw oedema, respectively. The most interesting seaweed extracts were found to be from Corallina elongata, Galaxaura oblongata, Laurencia obtusa and Udotea petiolata, where both extracts of each species induced a large antioedema effect in both models employed. None of the sponges assayed demonstrated antiinflammatory effects on carrageenan mouse paw oedema, however, some extracts elicited an inhibition of the oedema developed by TPA.     

秦皮素通过下调p70S6K抑制人黑色素瘤细胞增殖、迁移和侵袭研究

目的研究秦皮素对人黑色素瘤A375细胞的增殖、迁移、侵袭的影响及其作用机制。方法 A375细胞给予秦皮素和核糖体S6蛋白激酶(ribosome S6 protein kinase,P70S6K)抑制剂PF-4708671进行干预,采用细胞计数法考察秦皮素和PF-4708671对A375细胞增殖能力的影响;采用Western blotting法检测秦皮素和PF-4708671对m TORC1/p70S6K/S6通路关键蛋白及上皮-间充质转化(epithelial-mesenchymal transition,EMT)相关蛋白表达的影响;采用细胞划痕实验和Transwell实验考察秦皮素和PF-4708671对A375细胞迁移和侵袭的影响。结果秦皮素与PF-4708671均可显著抑制A375细胞的增殖、迁移和侵袭(P0.05、0.01)。秦皮素与PF-4708671均显著抑制p70S6K/S6通路活性,下调间质细胞标志蛋白和基质金属蛋白酶(matrix metalloproteinases,MMP)表达水平(P0.05、0.01)。结论秦皮素可能通过下调p70S6K抑制A375细胞的增殖、迁移与侵袭。