Antiproliferative effect of Acacia nilotica (L.) leaf extract rich in ethyl gallate against human carcinoma cell line KB.

OBJECTIVES: The objective of this study is to analyze the antiproliferative activity of Acacia nilotica (L.) leaf ethanolic extract against cancer KB cells and to determine the mode of cancer cytotoxicity. MATERIALS AND METHODS: In this study, high-performance liquid chromatography and liquid chromatography-mass spectrometry analysis were done to confirm the presence of ethyl gallate as a major bioactive phenolic in the leaf ethanolic extract of A. nilotica, further dose-dependent (0-120 µg/mL) antiproliferative effect was investigated in human carcinoma cell line KB. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, reactive oxygen species, mitochondrial membrane potential loss, DNA damage, and apoptosis were evaluated. RESULTS: A. nilotica leaf ethanolic extract (ANLEE) showed effective concentration (EC50) of 40 µg/mL. Interference of growth was significantly (P < 0.05) high in KB cells treated with ANLEE when compared to untreated control, but less when compared to the reference drug paclitaxel. In addition, the in vivo acute toxicity study demonstrated the safe limit of administration of 2000 mg/kg body weight ANLEE by the histological analysis in rats. The results from the present study indicate that mitochondria and DNA of KB cells are severely affected leading to apoptosis. CONCLUSIONS: ANLEE is a prospective source for cancer therapy and therefore should be highlighted to explore on its wide range of safety in rats and efficacy against human carcinoma cell line KB.

Synthesis and biological evaluation of acridine derivatives as antimalarial agents.

New N-alkylaminoacridine derivatives attached to nitrogen heterocycles were synthesized, and their antimalarial potency was examined. They were tested in vitro against the growth of Plasmodium falciparum, including chloroquine (CQ)-susceptible and CQ-resistant strains. This biological evaluation has shown that the presence of a heterocyclic ring significantly increases the activity against P. falciparum. The best compound shows a nanomolar IC(50) value toward parasite proliferation on both CQ-susceptible and CQ-resistant strains. The antimalarial activity of these new acridine derivatives can be explained by the two mechanisms studied in this work. First, we showed the capacity of these compounds to inhibit heme biocrystallization, a detoxification process specific to the parasite and essential for its survival. Second, in our search for alternative targets, we evaluated the in vitro inhibitory activity of these compounds toward Sulfolobus shibatae topoisomerase VI-mediated DNA relaxation. The preliminary results obtained reveal that all tested compounds are potent DNA intercalators, and significantly inhibit the activity of S. shibatae topoisomerase VI at concentrations ranging between 2.0 and 2.5 µM.

Apoptotic effect of Polygonum Cuspidatum in oral cancer cells through the regulation of specificity protein 1.

OBJECTIVES: The aim of this study was to evaluate the growth inhibitory and apoptosis-inducing effects and mechanisms of Polygonum cuspidatum root in oral cancer cells. MATERIALS AND METHODS: The testing materials were separated by normal-phase silica gel liquid chromatography. The effect of P. cuspidatum root on apoptotsis and its mechanism were performed using 3-(4,5-dimethylthiazol-20yl)-(3-carboxymethoxyphenyl)-2-(4-sulphophenyl)-2H-tetrazolium) (MTS) assay, western blot analysis, RT-PCR, promoter assay, and (4'-6-Diamidino-2-phenylindole) (DAPI) staining. RESULTS: The methanol extract of P. cuspidatum (MEPC) inhibited the proliferation of oral cancer cells by inducing caspase-dependent apoptosis. Protein and mRNA expression levels and the transactivation of Specificity protein 1 (Sp1) were markedly decreased in KB cells treated with MEPC. Ethyl acetate fraction (EA) from MEPC was more potent than aqueous fraction (AQ) from MEPC to induce apoptosis. F2, F3, and F4 from EA differentially inhibited the growth of KB cells, and it depends on the amount of Emodin in F2, F3, and F4. Moreover, Emodin inhibited oral cancer cell growth and induced caspase-dependent apoptosis by decreasing Sp1. MEPC also decreased an apoptosis-related downstream target of Sp1 protein, survivin. CONCLUSION: The results from this study strongly suggest that MEPC, its fraction, and Emodin may be potential bioactive materials to cause apoptosis mechanism via the down-regulation of Sp1 in oral cancer cells.

Cytotoxic farnesyl glycosides from Pittosporum pancheri.

Bioassay guided purification of the ethanolic extract of the bark of New Caledonian Pittosporum pancheri Brongn. and Gris (Pittosporaceae) led to the isolation and characterization of two new farnesyl monoglycosides, pancherins A and B. The structure of these compounds were determined on the basis of spectroscopic studies. The new compounds displayed a significant activity in the in vitro cytotoxic assay against KB cancer cell line, and pancherin A inhibits weakly farnesyl protein transferase.

Bioactive properties of plant species ingested by chimpanzees (Pan troglodytes schweinfurthii) in the Kibale National Park, Uganda.

We measured the biological activities of a selected sample (84 crude extracts) of 24 species eaten by wild chimpanzees (Pan troglodytes schweinfurthii) in the Kibale National Park, western Uganda, to assess their potential chemotherapeutic values. Antibacterial, antimalarial, and/or antileishmania activities were observed in some crude extracts, and five of these extracts showed a significant cytotoxicity against human tumor cells. Active compounds isolated from three plant parts occasionally ingested by chimpanzees (Diospyros abyssinica (Ebenaceae) bark, Uvariopsis congensis (Annonaceae) leaves, and Trichilia rubescens (Meliaceae) leaves) showed highly significant medicinal properties. Two novel antiparasitic limonoids were isolated from Trichilia rubescens and their molecular structures were determined. In addition to elucidating the natural equilibrium maintained between hosts and pathogens, our investigation of the diet of wild chimpanzees may serve as a guideline to discovering plants with bioactive properties that should be preserved from destruction because of their health maintenance value for great ape populations.

Anti-proliferative activity of essential oil extracted from Thai medicinal plants on KB and P388 cell lines.

Anti-proliferative activity of essential oil from 17 Thai medicinal plants on human mouth epidermal carcinoma (KB) and murine leukemia (P388) cell lines using MTT assay were investigated. An amount of 1 x 10(4)cells/well of KB cell line and 1 x 10(5) cells/well of P388 cell line were treated with the oil samples at different concentrations ranging from 0.019 to 4.962 mg/ml. In KB cell line, Guava (Psidium guajava L.) leaf oil showed the highest anti-proliferative activity with the IC(50) value of 0.0379 mg/ml (4.37 times more potent than vincristine) whereas Sweet Basil (Ocimum basilicum L.) oil gave the highest anti-proliferative activity with the IC(50) value of 0.0362 mg/ml (12.7 times less potent than 5-FU) in P388 cell line. The results demonstrated the potential of essential oil from Thai medicinal plants for cancer treatment.

Structure-activity relationships of the inhibitory effects of flavonoids on P-glycoprotein-mediated transport in KB-C2 cells.

We studied the effects of flavonoids, naringenin (flavanone), baicalein (flavone), kaempferol, quercetin, myricetin, morin, and fisetin (flavonols) as well as two glycosides of quercetin on P-glycoprotein (P-gp) function in multidrug-resistant P-gp overexpressing KB-C2 cells. Flavonoids such as kaempferol and quercetin increased the accumulation of rhodamine-123 dependent on their chemical structure. Analysis by flow cytometry indicated that the increase in substrate accumulation was due to the inhibition of substrate efflux. Naringenin, which lacks the 2,3-double bond in the C ring, had no effect, although it was more hydrophobic than myricetin, fisetin and morin. Therefore, the planar structure of the flavonoids seemed to be important for their interaction with P-gp. The effects of other flavonoids on the accumulation of daunorubicin were in the order of kaempferol>quercetin, baicalein>myricetin>fisetin, morin. Quercetin-3-O-glucoside and rutin had no effect. The order of the effects corresponded with that of the partition coefficients. Difference in the number and position of hydroxyl groups in flavonoid molecules by themselves seemed to have little effect. These results suggested that hydrophobicity as well as planar structure is important for the inhibitory effects of flavonoids on P-gp-mediated transport.

Potential antimalarial lead structures from fungi of marine origin.

Antiplasmodial and cytotoxicity testing of five highly oxygenated natural products (6R,12R,14R-colletoketol, 6R,11R,12R,14R-colletoketodiol, dihydrobotrydial, pycnidione, and 3R,4S-hydroxymellein), all derived from fungi of marine origin, showed one of them, pycnidione, to have activities against three different strains of Plasmodium falciparum in the sub-micromolar (microM) range. Although the mean selectivity index of 1 for the observed antiplasmodial activity of 4 is low, pycnidione's usefulness as a potential lead structure should not be ignored.

Five new cytotoxic triterpenoid saponins from the roots of Symplocos chinensis.

Five new triterpenoid saponins, named symplocososides G-K, were isolated from the roots of Symplocos chinensis. Their structures were elucidated by spectral and chemical methods as symplocososide G, 3beta-O-{[beta- D-glucopyranosyl(1-->2)][alpha-L-arabinofuranosyl(1-->4)]-beta-D-(3-O-acetyl)-glucuronopyranosyl}-21beta- O-[(2 Z)-3,7-dimethyl-2,6-octadienoyl]-22 alpha-O-(2-methylbutanoyl)-R1-barrigenol, symplocososide H, 3beta-O-{[beta-D-glucopyranosyl(1-->2)][alpha-L-arabinofuranosyl(1-->4)]- beta-D-(3-O-acetyl)-glucuronopyranosyl}-21beta-O-[(2E)3,7-dimethyl-2,6-octadienoyl]-22alpha-O-(2-methylbutanoyl)-R1-barrigenol, symplocososide I, 3beta-O-{[beta-D-glucopyranosyl(1-->2)][ alpha-L-arabinofuranosyl(1-->4)]-beta-D-(3- O-acetyl-6-O-methyl)-glucuronopyranosyl}-21beta-O-[(2 Z)3,7-dimethyl-2,6-octadienoyl]-22alpha-O-(2-methylbutanoyl)-R1-barrigenol, symplocososide J, 3 beta-O-{[ beta-D-glucopyranosyl(1-->2)][alpha-L-arabinofuranosyl(1-->4)]-beta-D-(3- O-acetyl)-glucuronopyranosyl}-21beta-O-[(2 Z)3,7-dimethyl-2,6-octadienoyl]-22alpha-O-benzoyl-R1-barrigenol, and symplocososide K, 3beta-O-{[beta-D-glucopyranosyl (1-->2)][alpha-L-arabinofuranosyl(1-->4)]- beta-D-(3-O-acetyl-6-O-methyl)-glucuronopyranosyl}-21beta-O-[(2Z)3,7-dimethyl-2,6-octadienoyl]-22alpha-O-benzoyl-R1-barrigenol. Symplocososides G-K showed significant cytotoxicity against cancer cell lines KB, HCT-8, Bel-7402, BGC-823 and A549 with IC50 values ranging from 0.82 microM to 5.09 microM, except for symplocososide I against cancer cell lines KB, BGC-823, A549 and symplocososide K against cancer cell line BGC-823 with IC50 values >10.00 microM.

[Chemical constituents from marine alga Chaetomorpha basiretorsa].

OBJECTIVE: To investigate the chemical constituents of marine alga Chaetomorpha basiretorsa. METHOD: Compounds were isolated by normal phase silica gel and Sephadex LH-20 gel colum chromatography, reverse phase MPLC, reverse phase HPLC and recrystallization. Their structures were elucidated by spectroscopic methods including MS, IR, NMR, and X-ray crystalography. Cytotoxicity of the compounds were screened by using standard MTT method. RESULT: Nine compounds were isolated from C. basiretorsa and their structures were identified as N-phenyl-2-naphthalenamine( I ), dibutyl phthalate( II ), diisobutyl phthalate( III ), 1-phenyl-ethane-1, 2-diol( IV ), 2-hydrox-gamma-benzaldehyde( V ), diethyleneglycol monobenzoate( VI ), uracil( VII ), thymine( VIII ) and thymidine( IX ). CONCLUSION: All these compounds were obtained from this genus for the first time, N-phenyl-2-naphthalenamine and diethyleneglycol monobenzoate were first reported from the marine organisms. Compound I and VII showed moderate activity against KB cell(IC50 10.15 microg x mL(-1) for I and 3.79 microg x mL(-1) for VII ) and MCF-7 cell(IC50 3.24 microg x mL(-1) for VII).

New cytotoxic prenylated isoflavonoids from Bituminaria morisiana.

Using cytotoxicity against KB cancer cells as a lead, bioguided-fractionation of the petroleum ether and ethyl acetate extracts of Bituminaria morisiana leaves led to the isolation of two new pterocarpans, namely 3,9-dihydroxy-4-(3,3-dimethylallyl) [6a R, 11a R]-pterocarpan, 3-hydroxy-4-(3,3-dimethylallyl)-4'',5''-dehydropyrano[8,9:2'',3''][6a R,11a R]-pterocarpan and one new isoflavone identified as 4',5''-dihydroxy-6''-methoxy-4'',4''-dimethyl-4'',5''-dihydro-6'' H-pyrano[2'',3'':7,8]-isoflavone. Moreover, two known pterocarpans, erybraedin C and bitucarpin A, three known isoflavones, daidzein, 8-prenyldaidzein and bidwillon C, one known furocoumarin, pseudoisopsoralen and one known coumestan, coumestrol were isolated. The structures of the isolated compounds were established by means of 1D and 2D NMR spectroscopy, as well as mass spectrometry. Further cytotoxicity tests against cells related to the immune system (Jurkat T, Mono-Mac-6 and polymorphonuclear cells) showed a moderate activity of the known pterocarpan erybraedin C against all cell lines used (IC (50) values between 17.6-28.8 microM). In addition, erybraedin C was found to induce necrosis in leukaemia Jurkat T cells.

Anti-staphylococcal and cytotoxic compounds from Hyptis pectinata.

Bioassay-guided fractionation of a CHCl (3) extract prepared from the Mexican medicinal plant Hyptis pectinata led to the isolation of four pyrones, pectinolides A-C ( 1-3) and H ( 4). Activity was tracked using cultured KB cells. Multidrug-resistant strains of Staphylococcus aureus were sensitive to pectinolide H ( 4; KB > 20 microg/mL) in the concentration range of 32-64 microg/mL. The absolute stereochemistry of this new compound was established as 5 S-[(4 S-acetyloxy)-(1 S-hydroxy)-2 Z-octenyl]-2(5 H)-furanone on the basis of spectral, chiroptical data and chemical correlation with pectinolide A ( 1). Mosher ester derivatives were used with pectinolide B ( 2) for confirmation of the 3'-( S) absolute stereochemistry on the side chain chiral center of pectinolides A-C.

Echinosulfonic acid D: an ESI MSn evaluation of a new cytotoxic alkaloid from the New-Caledonian sponge Psammoclemma sp.

A new bromoindolesulfonic acid derivative, echinosulfonic acid D (1) was isolated from the New-Caledonian sponge Psammoclemma sp. in a minute quantity. The structure of the alkaloid was established by spectroscopic methods and, in particular, by ESI MSn experiments. Echinosulfonic acid D was cytotoxic to KB cells (IC50 2 microg/mL).

Four new 6-nor5(6-->7)abeo-abietane type diterpenes and antitumoral cytotoxic diterpene constituents from the bark of Taiwania cryptomerioides.

Four new 6-nor-5(6-->7) abeo-abietane type diterpenes designated as taiwaniaquinone G, taiwaniaquinone H, taiwaniaquinol E and taiwaniaquinol F and eight known diterpenes, taiwaniaquinones A (5), D (6), E, F (8), and taiwaniaquinols A (9), B, C (11), D (12) were isolated from the bark of Taiwania cryptomerioides. Their structures were elucidated on the basis of spectroscopic studies. These twelve diterpenes were evaluated for in vitro antitumoral cytotoxic activity. The result demonstrated that compounds 5, 6, 8, 9, 11, and 12 bearing an aldehyde group possessed potent cytotoxic activity against KB epidermoid carcinoma cancer cell lines with IC50 values of 6.9, 7.2, 4.4, 8.3, 8.1, and 3.5 microM, respectively.

Effects of dietary chemopreventive phytochemicals on P-glycoprotein function.

The effects of dietary phytochemicals on P-glycoprotein function were investigated using human multidrug-resistant carcinoma KB-C2 cells and the fluorescent P-glycoprotein substrates daunorubicin and rhodamine 123. The effects of natural chemopreventive compounds, capsaicin found in chilli peppers, curcumin in turmeric, [6]-gingerol in ginger, resveratrol in grapes, sulforaphane in broccoli, 6-methylsulfinyl hexyl isothiocyanate (6-HITC) in Japanese horseradish wasabi, indole-3-carbinol (I3C) in cabbage, and diallyl sulfide and diallyl trisulfide in garlic, were examined. The accumulation of daunorubicin in KB-C2 cells increased in the presence of capsaicin, curcumin, [6]-gingerol, and resveratrol in a concentration-dependent manner. The accumulation of rhodamine 123 in KB-C2 cells was also increased, and the efflux of rhodamine 123 from KB-C2 cells was decreased by these phytochemicals. Sulforaphane, 6-HITC, I3C, and diallyl sulfide and diallyl trisulfide had no effect. These results suggest that dietary phytochemicals, such as capsaicin, curcumin, [6]-gingerol, and resveratrol, have inhibitory effects on P-glycoprotein and potencies to cause drug-food interactions.

Cytotoxic and antimicrobial constituents of the bark of Diospyros maritima collected in two geographical locations in Indonesia.

Bioactivity-directed fractionation of extracts of two Diospyros maritima bark samples from Indonesia,one collected at sea level in a beach forest in Java and the other collected at a slight elevation away from the sea shore on the island of Lombok, yielded a diverse set of secondary metabolites. The naphthoquinone plumbagin (1), although found in extracts of both specimens, constituted a much larger percentage of the former sample, which also yielded a series of plumbagin dimers, maritinone (2), chitranone (3), and zeylanone (4). The latter sample yielded a new naphthoquinone derivative, (4S)-shinanolone (5), and a new natural product coumarin, 7,8-dimethoxy-6-hydroxycoumarin (6), along with three other analogues of plumbagin, 2-methoxy-7-methyljuglone (7), 3-methoxy-7-methyljuglone (8), and 7-methyljuglone (9). The structures of compounds 5 and 6 were elaborated by physical, spectral, and chemical methods. All of the isolates were evaluated in both cytotoxicity and antimicrobial assays, and structure-activity relationships of these naphthoquinones are proposed. Plumbagin (1) and maritinone (2) were evaluated also for in vivo antitumor activity in the hollow fiber assay, but both were found to be inactive.

Cytotoxic alkaloids from the roots of Tylophora atrofolliculata.

Four new phenanthroindolizidine alkaloids, tylophoridicines C-F, together with three known ones, R-(+)-deoxytylophorinidine, tylophorinine and tylophorinidine, were isolated from the roots of Tylophora atrofolliculata. The structures were determined on the basis of spectral evidence. These alkaloids exhibited cytotoxic activity in vitro on HCT-8 cell (with IC50 values in the range 0.083 to 18.99 microM) and KB cell (in the range 3.56 to 18.22 microM) lines.

Eudesmane derivatives and other sesquiterpenes from Laggera alata.

Three new eudesmane sesquiterpenes, 5 beta-hydroxyilicic acid (1), 5 alpha-hydroxyl-4-epi-ilicic acid methyl ester (2), and 3 alpha-hydroxyilicic acid (3), together with 12 known sesquiterpenes were isolated from the aerial part of Laggera alata. Their structures were elucidated primarily by NMR and mass spectroscopic methods. The structures of 1 and 2 were confirmed by X-ray crystallography.

Reversal of cancer multidrug resistance by tea polyphenol in KB cells.

Tea polyphenols, (-)-epigallocatechin gallate in particular, were examined for their modulating effects on the drug resistance KB-A-1 cells and drug sensitive KB-3-1 cells. Both KB-3-1 and KB-A-1 cells were equally sensitive to tea polyphenol and (-)-epigallocatechin gallate. When 10 microgram/ml (-)-epigallocatechin gallate or 40 microgram/ml tea polyphenol were present simultaneously with doxorubicin, the IC50 of doxorubicin on KB-A-1 cells decreased from 10.3 +/- 0.9 microgram/ml to 4.2 +/- 0.2 or 2.0 +/- 0.1 microgram/ml. Tea polyphenol and (-)-epigallocatechin gallate enhanced the cytotoxicity of doxorubicin on KB-A-1 cells by 5.2 and 2.5 times, respectively, but did not show a modulating effect on KB-3-1 cells. Both tea polyphenol and (-)-epigallocatechin gallate showed reversal effects on the multidrug resistance phenotype.