Apoptosis induced by doxorubicin in neurotumor cells is divorced from drug effects on ceramide accumulation and may involve cell cycle-dependent caspase activation

Doxorubicin (0.5 microgram/ml) induced caspase-dependent apoptosis in SH-SY5Y neuroblastoma and CHP-100 neuroepithelioma cells. The apoptotic response started to be evident approximately 15 h after drug administration and, as monitored over a 48-h period, was more pronounced in CHP-100 than in SH-SY5Y cells. In both systems, apoptosis was accompanied by elevation of intracellular ceramide levels. Ceramide accumulation was blocked by the ceramide synthase inhibitor fumonisin B(1) (25 microM); this compound, however, did not prevent drug-induced apoptosis. Untreated cells from both lines expressed negligible p53 levels; on the other hand, whereas p53 and p21(Cip1/Waf1) were rapidly up-regulated in doxorubicin-treated SH-SY5Y cells, such a response was not observed in CHP-100 cells. Doxorubicin induced a G(2)/M phase block in both cell lines, but whereas the G(1) phase was markedly depleted in CHP-100 cells, it was substantially retained in SH-SY5Y cells. In the latter system, double G(1) and G(2)/M block largely preceded cell death; however, as apoptosis underwent completion, it selectively targeted late S and G(2)/M cells. Moreover, apoptosis suppression by caspase inhibition did not result in a recovery of the G(1) cell population. These results support the notion that doxorubicin-induced apoptosis and ceramide elevation are divorced events in neuroectodermal tumors and that p53 function is at least dispensable for apoptosis completion. Indeed, as G(1) cells appear to be refractory to doxorubicin-induced apoptosis, p53 up-regulation and p21(Cip1/Waf1) expression may provide an unfavorable setting for the apoptotic action of the drug.     

Inhibition of p38/CREB phosphorylation and COX-2 expression by olive oil polyphenols underlies their anti-proliferative effects

We investigated the anti-proliferative effects of an olive oil polyphenolic extract on human colon adenocarcinoma cells. Analysis indicated that the extract contained hydroxytyrosol, tyrosol and the various secoiridoid derivatives, including oleuropein. This extract exerted a strong inhibitory effect on cancer cell proliferation, which was linked to the induction of a G2/M phase cell cycle block. Following treatment with the extract (50 microg/ml) the number of cells in the G2/M phase increased to 51.82+/-2.69% relative to control cells (15.1+/-2.5%). This G2/M block was mediated by the ability of olive oil polyphenols (50 microg/ml) to exert rapid inhibition of p38 (38.7+/-4.7%) and CREB (28.6+/-5.5%) phosphorylation which led to a downstream reduction in COX-2 expression (56.9+/-9.3%). Our data suggest that olive oil polyphenols may exert chemopreventative effects in the large intestine by interacting with signalling pathways responsible for colorectal cancer development.     

Differential effects of imatinib on PDGF-induced proliferation and PDGF receptor signaling in human arterial and venous smooth muscle cells

Platelet-derived growth factor (PDGF) has been implicated in smooth muscle cell (SMC) proliferation, a key event in the development of myointimal hyperplasia in vascular grafts. Recent evidence suggests that the PDGF receptor (PDGFR) tyrosine kinase inhibitor, imatinib, can prevent arterial proliferative diseases. Because hyperplasia is far more common at the venous anastomosis than the arterial anastomosis in vascular grafts, we investigated whether imatinib also inhibited venous SMC (VSMC) proliferation, and examined possible differences in its mechanism of action between VSMC and arterial SMC (ASMC). Human ASMC and VSMC were stimulated with PDGF-AB, in the presence or absence of imatinib (0.1-10 microM). Proliferation was assayed using the 5-bromo-2'-deoxyuridine (BrdU) incorporation assay, while PDGFR, Akt and ERK1/2-mitogen activated protein kinase (MAPK) signaling pathways were investigated by immunoblotting. The proliferative response to PDGF at 50 and 100 ng/ml was 32 and 43% greater, respectively, in VSMC than in ASMC. Similarly, PDGF-stimulated proliferation was more sensitive to inhibition by imatinib in VSMC than ASMC (IC(50) = 0.05 microM vs. 0.4 microM; P < 0.01). Imatinib also more effectively inhibited PDGF-induced phosphorylation of PDGFRbeta and Akt in VSMC, compared to ASMC. These data highlight inherent pharmacodynamic differences between VSMC and ASMC in receptor and cell signaling functions and suggest that imatinib therapy may be useful for the prevention of venous stenosis in vascular grafts.     

Combination of the novel farnesyltransferase inhibitor RPR130401 and the geranylgeranyltransferase-1 inhibitor GGTI-298 disrupts MAP kinase activation and G(1)-S transition in Ki-Ras-overexpressing transformed adrenocortical cells.

To test the Kirsten-Ras (Ki-Ras) alternative prenylation hypothesis in malignant transformation, we used a novel farnesyltransferase inhibitor competitive to farnesyl-pyrophosphate, RPR130401, and a CaaX peptidomimetic geranylgeranyltransferase-1 inhibitor GGTI-298. In Ki-Ras-overexpressing transformed adrenocortical cells, RPR130401 at 1-10 microM inhibited very efficiently the [(3)H]farnesyl but not [(3)H]geranylgeranyl transfer to Ras. However, proliferation of these cells was only slightly sensitive to RPR130401 (IC(50)=30 microM). GGTI-298 inhibited the growth of these cells with an IC(50) of 11 microM but cell lysis was observed at 15 microM. The combination of 10 microM RPR130401 and 10 microM GGTI-298 inhibited efficiently (80%) cell proliferation. These combined inhibitors but not each inhibitor alone blocked the cell cycle in G(0)/G(1) and disrupted MAP kinase activation. Thus, combination of two inhibitors, at non-cytotoxic concentrations, acting on the farnesyl-pyrophosphate binding site of the farnesyltransferase and the CaaX binding site of the geranylgeranyltransferase-1 respectively is an efficient strategy for disrupting Ki-Ras tumorigenic cell proliferation.     

Inhibition of LPS-induced NO production by the oleogum resin of Commiphora wightii and its constituents

Three new (1-3) and five known compounds (4-8) were isolated from the oleogum resin of Commiphora wightii (Arnott.) Bhanol. Their structures were elucidated by spectroscopic and chemical methods. The MeOH extract and the EtOAc-sol. fraction were found to demonstrate significant inhibition of NO formation in lipopolysaccharide (LPS)-activated murine macrophages J774.1 in vitro (IC(50) values of 16.4 and 12.8 microg/ml, respectively). When compared with curcumin (IC(50) value of 12.3 microM), Z- and E-Guggulsterones (4 and 5, respectively) were the most potent inhibitors of NO production (IC(50) values of 1.1 and 3.3 microM, respectively), followed by myrrhanol A (7) and myrrhanone A (8) (IC(50) values of 21.1 and 42.3 microM, respectively). Guggulsterone-M (1) and its didehydro derivative (2) were weak inhibitors, while guggulsterols I (6) and Y (3) were inactive (IC(50) >500 microM).     

Cytotoxic activities of Coriolus versicolor (Yunzhi) extract on human leukemia and lymphoma cells by induction of apoptosis

Coriolus versicolor (CV), also known as Yunzhi, is one of the commonly used Chinese medicinal herbs. Although recent studies have demonstrated its antitumour activities on cancer cells in vitro and in vivo, the exact mechanism is not fully elucidated. Hence, the objective of this study was to examine the in vitro cytotoxic activities of a standardized aqueous ethanol extract prepared from Coriolus versicolor on a B-cell lymphoma (Raji) and two human promyelocytic leukemia (HL-60, NB-4) cell lines using a MTT cytotoxicity assay, and to test whether the mechanism involves induction of apoptosis. Cell death ELISA was employed to quantify the nucleosome production resulting from nuclear DNA fragmentation during apoptosis. The present results demonstrated that CV extract at 50 to 800 microg/ml dose-dependently suppressed the proliferation of Raji, NB-4, and HL-60 cells by more than 90% (p < 0.01), with ascending order of IC50 values: HL-60 (147.3 +/- 15.2 microg/ml), Raji (253.8 +/- 60.7 microg/ml) and NB-4 (269.3 +/- 12.4 microg/ml). The extract however did not exert any significant cytotoxic effect on normal liver cell line WRL (IC50 > 800 microg/ml) when compared with a chemotherapeutic anticancer drug, mitomycin C (MMC), confirming the tumour-selective cytotoxicity. Nucleosome productions in HL-60, NB-4 and Raji cells were significantly increased by 3.6-, 3.6- and 5.6-fold respectively upon the treatment of CV extract, while no significant nucleosome production was detected in extract-treated WRL cells. The CV extract was found to selectively and dose-dependently inhibit the proliferation of lymphoma and leukemic cells possibly via an apoptosis-dependent pathway.     

白介素-10抑制TNF-α诱导的血管平滑肌细胞增殖

研究观察了重组人白介素 10 (rhIL 10 )对肿瘤坏死因子 (TNF α)刺激的离体大鼠胸主动脉血管平滑肌细胞增殖、细胞周期及对p4 4 /p4 2丝裂素活化蛋白激酶的影响。实验培养大鼠主动脉血管平滑肌细胞 ,采用MTS/PES法确定血管平滑肌细胞 (vascularsmoothmusclecells,VSMCs)的增殖状态 ;应用流式细胞术测定细胞周期 ;利用p4 4 / 4 2磷酸化抗MAPK抗体的蛋白免疫印迹法测定MAPK蛋白表达。结果显示 :( 1)TNF α处理组与对照组相比 ,TNF α对VSMC增殖具有明显的刺激作用 (P <0 0 5 )。rhIL 10单独应用对VSMCs生长没有影响 (P >0 0 5 )。在TNF α刺激下 ,低至 10ng/ml的rhIL 10可抑制VSMCs的生长 (P <0 0 5 )。流式细胞术测定的结果显示 ,rhIL 10分别可使TNF α作用下的VSMC大部分处于G0 /G1期 ,与对照组相比有明显差异 (P <0 0 1)。 ( 2 )TNF α对p4 4 /p4 2MAPK蛋白表达有显著的增强作用 ,此作用可被rhIL 10抑制。结果提示 ,rhIL 10可抑制TNF α诱导的VSMC增殖及p4 4 /p4 2丝裂素活化蛋白激酶的表达     

Application of a continuous bioreactor cascade to study the effect of linoleic acid on hybridoma cell physiology

The aim of the present study is to demonstrate the use of controlled bioreactors for toxicological studies. As a model system the effect of linoleic acid on hybridoma cells is studied in two well-controlled continuously operated bioreactors placed in series. In the first reactor the effect on rapid proliferating cells can be studied, while in the second reactor a special steady state is created, which allows studying the effect on apoptotic cells. Experiments are done at 0, 25, and 50 microM linoleic acid. At the end of the experiment with 50 microM linoleic acid, the concentration of linoleic acid is increased stepwise to determine the cytotoxic level. For rapid proliferating cells exposed to 25 and 50 microM stimulation of growth was observed. At 50 microM there was at the same time an increase in cell death through apoptosis. For stressed apoptotic cells linoleic acid caused partial growth inhibition at 25 and 50 microM and arrest of cell proliferation in the G(2)/M phase at 50 microM. For both, rapid proliferating cells and stressed apoptotic cells, complete growth inhibition occurred at 85 microM, with cells being arrested in the G(2)/M phase and dying mainly through necrosis. Cells in the bioreactor system appeared to be more sensitive towards linoleic acid than cells grown in multi-well plates. (IC(50) = 300 microM; IC(100) = 400 microM). Altogether the results of the present study reveal that the biostat experiments allow detailed analysis of the effect of a bioactive ingredient on cell physiology and behavior.     

Effects of Cl- channel blockers on endothelin-1-induced proliferation of rat vascular smooth muscle cells

The effects of Cl- channel blockers on endothelin-1 (ET-1)-induced proliferation of rat aortic vascular smooth muscle cells (VSMC) were examined. We found ET-1 concentration-dependently increased cell count and [3H]-thymidine incorporation into VSMC, with EC50 values of 24.8 and 11.4 nM, respectively. Both nifedipine and SK&F96365 inhibited 10 nM ET-1-induced [3H]-thymidine incorporation into VSMC with the maximal inhibitory concentrations of 1 and 10 microM, respectively. DIDS inhibited 10 nM ET-1-induced increase in cell count and [3H]-thymidine incorporation into VSMC in a concentration-dependent manner, whereas other Cl- channel blockers including IAA-94, NPPB, DPC, SITS and furosemide did not produce these effects. 3 microM DIDS reduced 10 nM ET-1-induced sustained increase in cytoplasmic Ca2+ concentration ([Ca2+]) by 52%. Pretreatment of VSMC with 1 microM nifedipine completely inhibited the DIDS effect on 10 nM ET-1-induced [3H]-thymidine incorporation into VSMC and sustained increase in [Ca2+]i, whereas pretreatment with 10 microM SK&F96365 did not completely block these effects of DIDS. DIDS did not affect ET-1-induced Ca2+ release and 30 mM KCl-induced increase in [Ca2+]i. Our data suggest that DIDS-sensitive Cl- channels mediate VSMC proliferation induced by ET-1 by mechanisms related to membrane depolarization and Ca2+ influx through voltage-dependent Ca2+ channels.     

Tyrosine kinase-mediated activation of NADPH oxidase enhances proliferative capacity of diabetic vascular smooth muscle cells

To investigate a potential molecular basis for a link between diabetes and atherosclerosis, experiments were performed to determine the role of NADPH oxidase in the enhanced proliferative capacity of vascular smooth muscle cells (VSMC) from OLETF rat, an animal model of type 2 diabetes. An enhanced proliferative response to 10% fetal bovine serum with an increased cell cycle progression from G1 to S phase as well as an augmented superoxide generation with an increased NADPH oxidase activity were observed in diabetic versus control VSMC. Both the enhanced proliferation and superoxide generation in diabetic VSMC were significantly attenuated not only by diphenyleneiodonium (10 microM) and apocynin (100 microM), NADPH oxidase inhibitors but also by protein tyrosine kinase inhibitors such as genistein (100 microM) and AG 112 (100 microM). Furthermore, the enhanced NADPH oxidase activity in diabetic VSMC was significantly attenuated by genistein and AG112, but not by daidzein (100 microM), a genistein analogue devoid of protein tyrosine kinase inhibitory properties. Based on these results, it is suggested that the enhanced proliferative capacity of diabetic VSMC is closely related to the activation of NADPH oxidase that is induced through activation of protein tyrosine kinase.     

New 2-(1-adamantylcarbonyl)pyridine and 1-acetyladamantane thiosemicarbazones-thiocarbonohydrazones: cell growth inhibitory, antiviral and antimicrobial activity evaluation

The new thiosemicarbazones and thiocarbonohydrazones derived from 2-(1-adamantylcarbonyl)pyridine and 1-acetyladamantane were synthesized and evaluated for their inhibitory effect on tumor cell proliferation and their antiviral and antimicrobial activity. Thiosemicarbazone inhibited tumor cell proliferation (GI50's range: 2.4-100 microM and mean GI50 43.9 microM against various human leukemic cell lines) while thiosemicarbazone and thiocarbonohydrazone 5d exhibited significant inhibition of tumor cell proliferation (GI50's range 2.3-23.6 microM and mean GI50 7.2 microM for and GI50's range 2.4-32.4 microM and mean GI50 12.8microM for ). These GI50 values are comparable to that of 2-acetylpyridine thiosemicarbazone an important lead in TSC's family. The compounds did not afford specific activity against any of the viruses tested when examined at non-toxic concentrations. A weak activity was found for thiocarbonohydrazones against Gram-(+) bacteria (MIC(50) 117.3 and 133 microM, respectively). Using a combination of molecular mechanics calculations and NOE spectroscopy it was shown that the parent compounds and have opposite configuration around C=N bond. Whether this difference in structure can be correlated with the biological activity will be investigated in future studies.     

Hesperetin, a bioflavonoid, inhibits rat aortic vascular smooth muscle cells proliferation by arresting cell cycle

Diet can be one of the most important factors that influence risks for cardiovascular diseases. Hesperetin, a flavonoid present in grapefruits and oranges, is one candidate that may benefit the cardiovascular system. In this study, we have investigated the effect of hesperetin on the platelet-derived growth factor (PDGF)-BB-induced proliferation of primary cultured rat aortic vascular smooth muscle cells (VSMCs). Hesperetin significantly inhibited 50 ng/ml PDGF-BB-induced rat aortic VSMCs proliferation and [(3)H]-thymidine incorporation into DNA at concentrations of 5, 25, 50, and 100 microM. In accordance with these findings, hesperetin revealed blocking of the PDGF-BB-inducible progression through G(0)/G(1) to S phase of the cell cycle in synchronized cells. Western blot showed that hesperetin inhibited not only phosphorylation of retinoblastoma protein (pRb) and expressions of cyclin A, cyclin D, cyclin E, cyclin-dependent kinase 2 (CDK2) as well as proliferating cell nuclear antigen (PCNA) protein, but also downregulation of cyclin-dependent kinase inhibitor (CKI) p27(kip1), while did not affect CKI p21(cip1), p16(INK4), p53, and CDK4 expressions as well as early signaling transductions such as PDGF beta-receptor, extracellular signal-regulated kinase (ERK) 1/2, Akt, p38, and JNK phosphorylation. These results suggest that hesperetin inhibits PDGF-BB-induced rat aortic VSMCs proliferation via G(0)/G(1) arrest in association with modulation of the expression or activation of cell-cycle regulatory proteins, which may contribute to the beneficial effect of grapefruits and oranges on cardiovascular system.     

Thrombospondin-1-induced vascular smooth muscle cell chemotaxis: the role of the type 3 repeat and carboxyl terminal domains

Thrombospondin-1 (TSP-1), an acute phase reactant implicated in vascular disease, is a matricellular glycoprotein with six domains that confer different functions. The authors have shown TSP-1 induces vascular smooth muscle cell (VSMC) chemotaxis via extracellular signal-regulated kinases-1 and -2 (ERK) and p38 kinase (p38) and that a fusion protein of the carboxyl terminal (COOH) and type 3 repeat (T3) domains independently induce VSMC chemotaxis. The purpose of this study was to determine whether COOH-, T3-induced VSMC chemotaxis, or both, is dependent upon ERK or p38 activation. To determine if the T3, COOH, or type 2 repeat domain (T2, control domain not associated with chemotaxis) activate ERK, p38, or both, VSMCs were exposed to each fusion protein (20 microg/ml for 15, 30, 60, or 120 min), serum-free media (SFM, negative control), or TSP-1 (20 microg/ml for 30 min, positive control). Western immunoblotting was performed for activation studies. Using a microchemotaxis chamber, VSMCs pre-incubated in SFM, DMSO (vehicle control), PD98059 (10 microM), or SB202190 (10 microM) were exposed to each domain, TSP-1, or SFM. After 4 h (37 degrees C), migrated VSMCs were recorded as cells/five fields (400 x) and analyzed by paired t-test. ERK was activated by T2, T3, and COOH. However, p38 was activated by T3 and COOH, but not T2. T3 and COOH-induced VSMC chemotaxis were inhibited by PD98059 or SB202190, but more completely by SB202190. The T2 domain had no effect on VSMC chemotaxis. These results suggest activation of the p38 pathway may be more specific than ERK for COOH- and T3-induced VSMC chemotaxis.     

Antioxidant and radioprotective effect of the active fraction of Pilea microphylla (L.) ethanolic extract

The ethanolic extract of Pilea microphylla (L.) was defatted, successively fractionated with acetone and the residue so obtained was found to be most potent when subjected to detailed free radical scavenging and in vivo radioprotection studies. The most active fraction reacts with free radicals, such as DPPH (50 microM), ABTS(.)(-) (100 microM) and (.)OH (generated by Fenton reaction) with IC(50) value of 23.15 microg/ml, 3.0 microg/ml and 310 microg/ml, respectively. The most active fraction inhibited iron-induced lipid peroxidation in phosphatidyl choline liposomes with an IC(50) of 13.74 microg/ml. The kinetics of scavenging of DPPH and ABTS(.)(-) radicals were followed at different concentrations of the fraction by employing stopped-flow studies. The observed first order decay rate constants at 200 microg/ml and 50 microg/ml of fraction with DPPH (50 microM) and ABTS(.)(-) (50 microM) were found to be 0.4s(-1) and 2.1s(-1), respectively. The fraction when screened for in vivo radioprotection in Swiss albino mice showed 80% protection at a dose of 900 mg/kg and with a DRF of about 1.12. The fraction was also found to protect livers of irradiated mice from depletion of endogenous antioxidant enzymes like glutathione, GST, SOD, catalase and thiols. The fraction also protected the villi height, increased the number of crypt cells while offering general protection to the intestine from acute radiation effects. The fraction also protected the hematopoietic system as assessed by endogenous spleen colony assay, contributing to the overall radioprotective ability.     

Protective effect of keishi-bukuryo-gan and its constituent medicinal plants against nitric oxide donor-induced neuronal death in cultured cerebellar granule cells.

Keishi-bukuryo-gan (Gui-Zhi-Fu-Ling-Wan) (KBG) is a traditional Chinese/Japanese medical (Kampo) formulation that has been administered to patients with "Oketsu" (blood stagnation) syndrome. In the process of neuronal cell death induced by brain ischemia, excessive generation of nitric oxide (NO) free radicals is implicated in the neurotoxicity. In the present study, we examined the protective effects of KBG and its constituent medicinal plants against NO donors, sodium nitroprusside (SNP) and 2,2'-(hydroxynitrosohydrazino)bis-ethanamine (NOC18)-induced neuronal death in cultured rat cerebellar granule cells (CGCs). MTT assay showed cell viability to be significantly increased by the addition of KBG extract (KBGE) (100 microg/ml), Cinnamomi Cortex extract (CCE) (3, 10 and 30 microg/ml), Paeoniae Radix extract (PRE) (100 microg/ml) and Moutan Cortex extract (MCE) (10 and 30 microg/ml) compared with exposure to SNP (30 microM, 24 h) only. Also, cell viability was significantly increased by the addition of KBGE (100 and 300 microg/ml), CCE (30 and 100 microg/ml), PRE (100 and 300 microg/ml) and MCE (30 and 100 microg/ml) compared with exposure to NOC 18 (100 microM, 48 h) only. Persicae Semen extract and Hoelen extract did not protect against NO donor-induced neuronal death. These results suggest that KBG has protective effect against NO-mediated neuronal death in cultured CGCs and that it is derived from Cinnamomi Cortex, Paeoniae Radix and Moutan Cortex.     

Amadori-glycated albumin-induced vascular smooth muscle cell proliferation and expression of inhibitor of apoptosis protein-1 and nerve growth factor-gamma

We investigated the effects of Amadori-glycated serum albumin (GSA) on cell proliferation as well as expressions of antioxidant enzyme genes and marker genes associated with signal transduction pathways in rat aortic vascular smooth muscle cells (VSMCs). Quiescent VSMCs treated with GSA (0-500 microg/mL, 48 h) exhibited a dose-dependent increase in proliferation that was prevented by PD98059 (25 microM), suggesting a MAPK-dependent signaling pathway. Compared with bovine serum albumin (BSA)-treated cells, the GSA (500 microg/mL, 24~h)-treated VSMCs showed a higher superoxide dismutase 2 gene expression in quantitative RT-PCR, suggesting the involvement of oxidative stress. In a focused oligonucleotide array containing 96 signal transduction-related genes, expression of inhibitor of apoptosis protein-1 (IAP-1), nerve growth factor-gamma (NGF-gamma), and c-jun genes was significantly higher in the GSA-treated VSMCs. These results suggest that induction of antiapoptotic proteins like IAP-1 and strong mitogens like NGF-gamma by GSA might further contribute to the VSMC proliferation and accelerated vascular remodeling in diabetes.     

Prostaglandin-H-synthase (PGHS)-1 and -2 microtiter assays for the testing of herbal drugs and in vitro inhibition of PGHS-isoenzyms by polyunsaturated fatty acids from Platycodi radix

In order to test inhibition of prostaglandin-H-synthase-1 and -2 (PGHS-1 and -2) by plant extracts, we have established two enzyme based in vitro assays with enzyme immunoassay (EIA) evaluation. The assays have been evaluated with known synthetic inhibitors and with plant extracts. In a screening of traditionally used Chinese herbs for anti-inflammatory activity, a series of n-hexane and dichloromethane extracts showed significant inhibitory effect in comparison with the known specific PGHS-2 inhibitors NS-398 (IC(50) = 2.6 microM) and nimesulide (IC(50) = 36 microM). The lipophilic extracts of the Chinese drug Jiengeng, the dried roots of Platycodon grandiflorum (Jacq.) A. DC. (Campanulaceae), showed good inhibitory activity against both PGHS isoenzymes. The directly prepared DCM-extract exhibited better activity against PGHS-2 (IC(50) = 4.0 microg/ml) than against PGHS-1 (IC(50) = 17.6 microg/ml). We identified fatty acids as main active constituents and quantified them. Linoleic acid showed the highest content (ca. 20% of the dried extract) and a high and preferential PGHS-2 inhibitory activity (IC(50) (PGHS-1) = 20 microM; IC(50) (PGHS-2) = 2 microM). The comparison of the concentration of linoleic acid and the inhibitory activity of the direct DCM-extract showed, that linoleic acid is mainly responsible for the in vitro activity of the extract on PGHS-2.     

A novel antimicrobial epoxide isolated from larval Galleria mellonella infected by the nematode symbiont, Photorhabdus luminescens (Enterobacteriaceae)

A novel antimicrobial epoxide, 2-isopropyl-5-(3-phenyl-oxiranyl)-benzene-1,3-diol (1), was identified from larval Galleria mellonella infected by a symbiotically associated bacterium-nematode complex (Photorhabdus luminescens C9-Heterorhabditis megidis 90). Its structure was determined with spectroscopic analysis and confirmed by chemical synthesis starting from a known antibiotic, 2-isopropyl-5-(2-phenylethenyl)-benzene-1,3-diol (2). Epoxide 1 was active against Bacillus subtilis, Escherichia coli, Streptococcus pyogenes, and a drug-resistant, clinical strain of Staphylococcus aureus (RN4220) with minimum inhibitory concentrations in the range of 6.25-12.5 microg/ml. Epoxide 1 was cytotoxic against human cancer cell lines, MCF-7 wt, H460, and Jurkat, with GI(50) of 2.14, 0.63, and 0.42 microM, respectively, but was less toxic on normal, mouse splenic lymphocytes with a GI(50) of 45.00 microM.