Induction of apoptosis by isothiocyanate sulforaphane in human cervical carcinoma HeLa and hepatocarcinoma HepG2 cells through activation of caspase-3.

Sulforaphane (SFN) is an isothiocyanate that is found in abundant quantities in many cruciferous vegetables including broccoli and cauliflower. Its inhibitory effects on tumor cell growth in vitro and in vivo, which is dependent on the direct effect on cancer cells, has attracted considerable attention. This study examined the effects of SFN on the growth of human cervical carcinoma HeLa and hepatocarcinoma HepG2 cells. The results showed that SFN inhibits the viability of both HeLa and HepG2 cells by inducing apoptosis, as evidenced by the formation of apoptotic bodies and the accumulation of the sub-G1 phase. RT-PCR and immunoblotting showed that treating the cells with SFN caused the down-regulation of anti-apoptotic Bcl-2 and Bcl-XL, and the up-regulation of pro-apoptotic Bax expression. SFN-induced apoptosis was associated with the proteolytic activation of caspase-3, and the degradation/cleavage of poly (ADP-ribose) polymerase and the beta-catenin protein. z-DEVD-fmk, a caspase-3 specific inhibitor, blocked the activation of caspase-3 and increased the survival of the SFN-treated HeLa and HepG3 cells, suggesting that caspase-3 activation is essential for SFN-induced apoptosis.

Induction of apoptosis by (Z)-stellettic acid C, an acetylenic acid from the sponge Stelletta sp., is associated with inhibition of telomerase activity in human leukemic U937 cells.

BACKGROUND: (Z)-stellettic acid C, an acetylenic acid from the marine sponge Stelletta sp., has been shown to have cytotoxic activity in some cancer cells; however, its mechanisms on malignant cell growth are not known. In this study, the potential of (Z)-stellettic acid C to induce apoptosis in human leukemic U937 cells and its effects on telomerase activity were investigated. METHODS: Cytotoxicity was evaluated by MTT assays. Apoptosis was detected using DAPI staining and annexin V fluorescein. The mRNAs of Bcl-2, inhibitor of apoptosis proteins (IAPs) family and Fas/FasL system were determined by RT-PCR. Caspases and telomerase activities were measured using colorimetric assay and telomeric repeat amplification protocol enzyme-linked immunosorbent assay (TRAP-ELISA), respectively. RESULTS: Exposure of U937 cells to (Z)-stellettic acid C resulted in growth inhibition and induction of apoptosis in a dose-dependent manner, which was associated with the modulation of Bcl-2 family expression, activation of caspases and downregulation of IAPs family members. (Z)-Stellettic acid C treatment markedly inhibited the activity of telomerase in a dose-dependent fashion. Additionally, the expression of human telomerase reverse transcriptase, a main determinant of the telomerase enzymatic activity, was progressively downregulated by (Z)-stellettic acid C treatment. CONCLUSIONS: These results suggest that (Z)-stellettic acid C could have a possible cancer therapeutic potential.

ATP-independent thermoprotective activity of Nicotiana tabacum heat shock protein 70 in Escherichia coli.

To study the functioning of HSP70 in Escherichia coli, we selected NtHSP70-2 (AY372070) from among three genomic clones isolated in Nicotiana tabacum. Recombinant NtHSP70-2, containing a hexahistidine tag at the amino-terminus, was constructed, expressed in E. coli, and purified by Ni(2+) affinity chromatography and Q Sepharose Fast Flow anion exchange chromatography. The expressed fusion protein, H(6)NtHSP70-2 (hexahistidine-tagged Nicotiana tabacum heat shock protein 70-2), maintained the stability of E. coli proteins up to 90 degrees C. Measuring the light scattering of luciferase (luc) revealed that NtHSP70-2 prevents the aggregation of luc without ATP during high-temperature stress. In a functional bioassay (1 h at 50 degrees C) for recombinant H(6)NtHSP70-2, E. coli cells overexpressing H(6)NtHSP70-2 survived about seven times longer than those lacking H(6)NtHSP70-2. After 2 h at 50 degrees C, only the E. coli overexpressing H(6)NtHSP70-2 survived under such conditions. Our NtHSP70-2 bioassays, as well as in vitro studies, strongly suggest that HSP70 confers thermo-tolerance to E. coli.

Methanol extract of the seaweed Gloiopeltis furcata induces G2/M arrest and inhibits cyclooxygenase-2 activity in human hepatocarcinoma HepG2 cells.

It was previously reported that a methanol extract of Gloiopeltis furcata (MEGF), a kind of edible seaweed, inhibited the growth of several human cancer cell lines. In the present study, the effect of MEGF on the growth of human hepatocarcinoma HepG2 cells and its effect on the cyclooxygenases (COXs) expression were investigated. MEGF markedly reduced the viability of HepG2 cells and induced the G2/M arrest of the cell cycle in a concentration dependent manner. These effects were associated with the down-regulation of cyclin A, up-regulation of cyclin-dependent kinase (Cdk) inhibitor p21 (WAF1/CIP1) and dephosphorylation of Cdc25C. Furthermore, it was found that MEGF decreased the levels of COX-2 mRNA and protein expression without significant changes in the levels of COX-1, which was correlated with a decrease in prostaglandin E(2) (PGE(2)) synthesis. These findings indicate that MEGF may have a possible therapeutic potential in hepatoma cancer patients.

Suppression of U937 human monocytic leukemia cell growth by dideoxypetrosynol A, a polyacetylene from the sponge Petrosia sp., via induction of Cdk inhibitor p16 and down-regulation of pRB phosphorylation.

Dideoxypetrosynol A, a polyacetylene from the marine sponge Petrosia sp., is known to exhibit significant selective cytotoxic activity against a small panel of human tumor cell lines, the mechanisms of which however, are poorly understood. The aim of the present study was to further elucidate the possible mechanisms by which dideoxypetrosynol A exerts its anti-proliferative action in cultured human monocytic leukemia U937 cells. We observed that the proliferation-inhibitory effect of dideoxypetrosynol A was due to the induction of G1 arrest in the cell cycle, the effects of which were associated with up-regulation of cyclin D1 and down-regulation of cyclin E, in a concentration-dependent manner without any change in cyclin-dependent-kinases (Cdks) expression. Dideoxypetrosynol A markedly induced the levels of Cdk inhibitor p16/INK4a expression. Furthermore, down-regulation of phosphorylation of retinoblastoma protein (pRB) by this compound was associated with enhanced binding of pRB and transcription factor E2F-1. Overall, our results demonstrate a combined mechanism involving the inhibition of pRB phosphorylation and induction of p16 as targets for dideoxypetrosynol A, may explain some of its anti-cancer effects.

New cytotoxic sulfated saponins from the starfish Certonardoa semiregularis.

Two new sulfated saponins designated as certonardosides P2 and I3 (1 and 2) were isolated from the brine shrimp active fraction of the MeOH extract of the starfish Certonardoa semiregularis. The structures were determined on the basis of spectral analysis. Compounds 1 and 2 were tested for cytotoxicity against five human tumor cell lines (A549, SK-OV-3, SK-MEL-2, XF498, and HCT15), and compound 1 displayed significant cytotoxicity against the SK-MEL-2 skin cancer cell.

Cytotoxic sterol derivatives from a marine sponge Homaxinella sp.

A bioactivity-guided fractionation of a marine sponge Homaxinella sp. has led to the isolation of three new (1-3) highly degraded sterols and four new 6-O-alkylated (6-9) sterols, along with known sterol derivatives. The degraded sterols (1-5) belong to the class incisterols, previously isolated from the marine sponge Dictyonella incisa. Mainly NMR and MS spectroscopic analyses established the gross structures of the new compounds. The relationship between the stereoisomerism of the side chain and HPLC retention time has also been discussed. The compounds were tested against a panel of five human solid tumor cell lines, and especially the degraded sterols (1-4) displayed significant cytotoxicity.

Induction of apoptosis by dideoxypetrosynol A, a polyacetylene from the sponge Petrosia sp., in human skin melanoma cells.

Dideoxypetrosynol A, a polyacetylene from the sponge Petrosia sp., is known to exhibit significant selective cytotoxicity against several human tumor cell lines. In the present study, we investigated the possible mechanisms by which dideoxypetrosynol A exerts its anti-proliferative action in cultured human SK-MEL-2 skin melanoma cells. Exposure of SK-MEL-2 cells to dideoxypetrosynol A resulted in growth inhibition and induction of apoptosis in a dose-dependent manner as measured by MTT assay, fluorescent microscopy and flow cytometry analysis. The increase in apoptosis was associated with a dose-dependent up-regulation in proapoptotic Bax expression and down-regulation of anti-apoptotic Bcl-2. Apoptosis-inducing concentrations of dideoxypetrosynol A induced caspase-3 and caspase-9 activation accompanied by proteolytic degradation of poly(ADP-ribose)-polymerase and selective down-regulation of cIAP-1. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anti-cancer activity of dideoxypetrosynol A.

Additional cytotoxic sterols and saponins from the starfish certonardoa semiregularis.

Twelve new (1-7, 9-13) polyhydroxysterols and two new saponins (14 and 15) were isolated from the starfish Certonardoa semiregularis by activity-guided fractionation. Compounds 1-7 are rare examples of 15-keto steroids from starfish. The side chain of compound 11 was also unprecedented in nature. The structures were determined by combined spectroscopic methods and chemical derivatization. These compounds were evaluated for cytotoxicity against a small panel of human solid tumor cell lines, and most of them exhibited considerable activity. One of the 15-keto sterols (6) displayed the highest potency, which is comparable to that of doxorubicin.

Estrogenic effects of Sedum sarmentosum Bunge in ovariectomized rats.

The aim of this study was to evaluate the effects of Sedum sarmentosun Bunge (SS) on the lipid on serum and the collagen content of the connective tissues in ovariectomized estrogen-deficient rats. Three groups were surgically ovariectomized. The fourth group was sham operated. From day 2 until day 37 after the ovariectomy, Sprague-Dawley female rats were randomly assigned to the following groups: sham-operated rats (sham), ovariectomized control rats (OVX-control), ovariectomized rats supplemented with an ethyl ether fraction of SS at 10 mg/kg bw/d (OVX-EE), ovariectomized rats supplemented an ethyl acetate fraction of SS at 10 mg/kg bw/d (OVX-EA). The SS fractions were orally administrated at 1 mL per day. The estrogenic effects of the ethyl ether and ethyl acetate fractions of SS, were investigated using one in vitro assay and two in vivo assays. The treatment of the partition of the ethyl ether and ethyl acetate layers of SS increased the transcriptional activity 0.7-fold and 0.5-fold compared to those that were given 17beta-estradiol treatment, respectively. The OVX rats were significantly heavier than the sham-operated rats at all times, but supplementation with the SS extracts tended to result in less weight gain than OVX-control. The serum triglyceride levels were significantly decreased after supplementation with the SS portion EE and EA layers. Supplementation with the SS extracts prevented a decrease in the collagen level in bone and cartilage tissues. This result indicates that the SS affects the collagen synthesis in ovariectomized rats. These results are consistent with the conclusions based on the estrogenic activities of SS. Therefore, it may be used to possibly improve the quality of life in menopausal women.

Inhibition of tyrosinase by protocatechuic aldehyde.

The purpose of this study was to determine the inhibitory action of protocatechuic aldehyde (PCA) on tyrosinase activity. PCA is one of the compounds found in the root of Salvia miltiorrhiza. Our study documented that PCA has a potent inhibitory effect on tyrosinase, which catalyzes the rate-limiting step of melanin biosynthesis. Although melanin biosynthesis has an essential function normally in human skin for defense against ultraviolet light of the sun, its abnormal activity as seen in pigmentation disorder could lead to serious medical problems. Our data showed that PCA, with concentrations ranging from 1 x 10(-5) M to 8 x 10(-5) M, exhibited dose-dependent inhibition of the enzyme activity with 50% of inhibition at 19.92 x 10(-6) M. A further kinetic analysis on PCA inactivation of tyrosinase activity revealed a competitive inhibition of the enzyme at the L-tyrosine binding site. The findings of our present study merit further research on the applicability of PCA as a potential agent for treatment of pigmentation disorder.

Active components from Artemisia iwayomogi displaying ONOO(-) scavenging activity.

Peroxynitrite (ONOO(-)) is one of cytotoxic species produced by the reaction between superoxide (*O(2) (-)) and nitric oxide (NO). The main aim of this study was to identify ONOO(-) scavenging constituents from herbs. Methanolic extracts derived from one hundred thirty eight herbs were screened out for their ONOO(-) scavenging activities. Twenty herbs showed excellent ONOO(-) scavenging activity in a dose dependent manner. Of them, Artemisia iwayomogi, which showed the highest activity, was fractioned with several solvents. The ONOO(-) scavenging activity of fractions was in order of ethyl acetate (EtOAc) > n-butanol (BuOH) > dichloromethane (CH(2)Cl(2)) > water (H(2)O) fraction. The EtOAc and the n-BuOH fractions were further purified to isolate active principles by column chromatography. Apigenin 7-methylether (genkwanin), apigenin 7,4'-di-O methylether, jaceosidin, and scopoletin from the EtOAc fraction and chlorogenic acid, 2,4-dihydroxy 6-methoxy acetophenone 4-O-beta-D-glucoside, quebrachitol, and scopolin from the n-BuOH fraction were identified. The scavenging activities of chlorogenic acid (IC(50) = 0.52 +/- 0.04 microM), genkwanin (IC(50) = 1.01 +/- 0.10 microM), and scopoletin (IC(50) = 1.03 +/- 0.15 micro M) were higher than or comparable to a well-known ONOO(-) scavenger, penicillamine (IC(50) = 1.76 +/- 0.18 microM), suggesting that those compounds might be developed as effective ONOO(-) scavengers for, prevention of the ONOO(-)-involved diseases.

Inhibitory effects of luteolin isolated from Ixeris sonchifolia Hance on the proliferation of HepG2 human hepatocellular carcinoma cells.

We investigated the anti-proliferative effects of luteolin and apigenin, isolated from Ixeris sonchifolia Hance, on HepG2 human hepatocellular carcinoma cells. In MTT assay luteolin showed more efficient anti-proliferative effects on cells than apigenin did. According to propidium iodide staining and flow cytometry studies, we postulated that these effects might be a result of cell cyde arrest. Hence we examined the changes of protein expressions related to cell cycle arrest. Western blotting data demonstrated that the down-regulated expression of CDK4 was correlated to the increase of p53 and CDK inhibitor p21(WAF1/CIP1) protein. These data suggest that luteolin may have potential as an anti-cancer agent.

Cytotoxic constituents of the leaves of Ixeris sonchifolia.

The ethyl acetate extract of the leaves of Ixeris sonchifolia afforded two new and two known sesquiterpene lactone glucosides of the guaiane-type, together with a known alkenol glucoside. The known compounds were identified as ixerin Z (1), ixerin Z-6'-p-hydroxyphenylacetate (2), and (Z)-3-hexen-1-ol-beta-D-glucopyranoside (3), respectively. The structures of the new compounds were elucidated as 11,13a-dihydroixerin Z [4, 3-hydroxy-2-oxo-guaia-1(10), 3-dien-5alpha,6beta,7alpha, 11betaH-12,6-olide-3-O-beta-D-glucopyranoside], and 3,10beta-dihydroxy-2-oxo-guaia-3,11(13)-dien-1alpha,5alpha,6alpha,7aH-12,6-olide-10-O-beta-D-glucopyranoside (5), respectively. The cytotoxicity of these compounds against human hepatocellular carcinoma cell (HepG2) and human melanoma cell (SK-MEL-2) was evaluated.

Cytotoxic and antimutagenic stilbenes from seeds of Paeonia lactiflora.

Cytotoxic and antimutagenic effects of a novel cis-epsilon-viniferin and five known stilbenes, transresveratrol, trans-epsilon-viniferin, gnetin H, suffruticosols A and B, isolated from the seeds of Paeonia lactiflora Pall. (Paeoniaceae) were determined against five different cancer cell lines, and mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Salmonella typhimurium TA100, respectively. Six stilbenes showed cytotoxic activity in a dose-dependent manner, and especially did potent cytotoxic activity against C6 (mouse glioma) cancer cell with IC50 values ranging from 8.2 to 20.5 microg/ml. trans-Resveratrol showed significant cytotoxic activity against HepG2 (liver hepatoma) and HT-29 (colon) human cancer cell lines with IC50 values of 11.8 and 25.2 g/ml, respectively. In contrast, trans-epsilon-viniferin and cis--viniferin, and gnetin H exhibited marked cytotoxic activity against Hela (cervicse) and MCF-7 (breast) human cancer cell lines with IC50 values of 20.4, 21.5, and 12.9 microg/ml, respectively. However, suffruticosol A and B had less cytotoxic effect against all cancer cells except C6. Meanwhile, six stilbenes exerted antimutagenic activity in a dose-dependent fashion. Of them, trans-resveratrol exhibited the strongest antimutagenic effect against MNNG with IC50 value of 27.0 microg/plate, while other five resveratrol oligomers also did moderate antimutagenic activity with IC50 values ranging from 31.7 to 35.2 microg/plate.

Peroxynitrite scavenging activity of herb extracts.

Peroxynitrite (ONOO(-)) is a cytotoxicant with strong oxidizing properties toward various cellular constituents, including sulphydryls, lipids, amino acids and nucleotides and can cause cell death, lipid peroxidation, carcinogenesis and aging. The aim of this study was to characterize ONOO(-) scavenging constituents from herbs. Twenty-eight herbs were screened for their ONOO(-) scavenging activities with the use of a fluorometric method. The potency of scavenging activity following the addition of authentic ONOO(-) was in the following order: witch hazel bark > rosemary > jasmine tea > sage > slippery elm > black walnut leaf > Queen Anne's lace > Linden flower. The extracts exhibited dose-dependent ONOO(-) scavenging activities. We found that witch hazel (Hamamelis virginiana L.) bark showed the strongest effect for scavenging ONOO(-) of the 28 herbs. Hamamelitannin, the major active component of witch hazel bark, was shown to have a strong ability to scavenge ONOO(-). It is suggested that hamamelitannin might be developed as an effective peroxynitrite scavenger for the prevention of ONOO(-) involved diseases.