Bioactive prenylated flavonoids from the stem bark of Artocarpus kemando

Four known prenylated flavonoids, artonins E (1) and O (2), artobiloxanthone (3), and cycloartobiloxanthone (4), were isolated from the stem bark of Artocarpus kemando by bioassay-guided fractionation using the DNA strand-scission and the KB cytotoxicity assays as monitors. Compounds 1 and 3 exhibited strong DNA strand-scission activity, and all four compounds were found to be cytotoxic.     

Antioxidant activity of Caesalpinia sappan heartwood

Antioxidant activity of Caesalpinia sappan heartwood was studied both by in vitro and in vivo models. The ethyl acetate, methanol and water extracts exhibited strong antioxidant activity as evidenced by the low IC50 values in both 1,1-diphenyl-2-picryl hydrazyl (DPPH) and nitric oxide methods. The values were found to be less or comparable to those of ascorbic acid and rutin, the standards used. Administration of the successive methanol and water extracts at 50 and 100 mg/kg body weight given for four days prior to carbon tetrachloride (CCl4) treatment caused a significant increase in the level of superoxide dismutase (SOD) and catalase and a significant decrease in the level of thiobarbituric acid reactive substances (TBARS), when compared to CCl4 treated control in both liver and kidney. These changes observed at 100 mg/kg body weight treatment were comparable to those observed for standard vitamin E at 50 mg/kg treatment. The results support significant antioxidant nature of Caesalpinia sappan heartwood extracts.     

Four butenolides are novel cytotoxic compounds isolated from the marine-derived bacterium,Streptoverticillium luteoverticillatum 11014

Four known butenolides were isolated from the ethyl acetate extracts of the culture broth of the marine-derived bacterium, Streptoverticillium luteoverticillatum, by bioassay-guided fractionation. The structures were identified on the basis of spectral data. The absolute configuration of compound (1) was determined by CD spectrum for the first time. Compounds 1-4 showed in vitro cytotoxicity against the murine lymphoma P388 and human leukemia K562 cell lines. This is the first report on the isolation of butenolides from the marine bacterium, Streptoverticillium luteoverticillatum, and their cytotoxic activities.     

Inhibition of cytochrome P450 3A4 by extracts and kavalactones of Piper methysticum (Kava-Kava)

Inhibitors of cytochrome P450 3A4 (CYP3A4) were identified in crude extracts from the rhizomes of Piper methysticum G. Forst. (Kava-Kava) using bioassay-guided fractionation. After preliminary purification of an ethyl acetate extract with solid phase extraction, the eluate was further fractionated by means of HPLC and fractions were tested for inhibitory potency using cDNA expressed CYP3A4. Positive fractions were analysed with LC/MS using electrospray ionisation and kavapyrones could be identified as the main CYP3A4 inhibitory components of Piper methysticum.     

The radical scavenging effects of stilbene glucosides from<Emphasis Type="Italic">Polygonum multiflorum</Emphasis>

The extract of the root of Polygonum multiflorum exhibited a significant antioxidant activity assessed by the DPPH radical scavenging activity in vitro. The bioassay-guided fractionation of the extract yielded a stilbene glucoside, (E)-2,3,5,4'-tetrahydroxystilbene-2-O-beta-d-glucopyranoside (1) as an active constituent responsible for the antioxidant property. Compound 1 demonstrated a moderate DPPH radical scavenging activity (IC50, 40 microM), while the corresponding deglucosylated stilbene 2 exhibited a much higher activity (IC50, 0.38 microM).     

Free radical scavenging and anti-inflammatory properties of <Emphasis Type="Italic">Lagerstroemia speciosa</Emphasis> (L)

The in vitro antioxidant activity of the successive extracts (ethyl acetate, ethanol, methanol and water) of the leaves of Lagerstroemia speciosa L. (Lythraceae) were studied by examining their superoxide, hydroxyl ion scavenging and by measuring lipid peroxidation. The ethyl acetate and ethanol extracts were found to possess greater antioxidant property than the methanol and water extracts. Anti-inflammatory activity of the ethyl acetate and ethanol extracts were examined using the carrageenan-induced acute inflammation and formalin-induced (chronic) paw edema models. In acute and chronic inflammation models, the ethyl acetate extract reduced the paw edema significantly in a dose-dependent manner. Whereas, ethanol extract did not show dose-dependent activity. This results suggests that the anti-inflammatory activity is possibly attributed to its free radical scavenging activity. It was found that ethyl acetate extract reduced the inflammation more significantly than the ethanol extract.     

Anticoagulant 1,2,3,4,6-pentagalloyl-β-d-glucopyranose isolated from geranium (Pelargonium inquinans Ait)

Geranium (Pelargonium inquinans Ait) leaves were extracted with 80% MeOH, and partitioned into n-hexane, ethyl acetate, BuOH and H2O to isolate the anticoagulant principles. The EtOAc fraction was found to be the most active, and was further purified using silica and octadecylsilane column chromatography employing a bioassay-guided fractionation method. The active compound was isolated and identified as 1,2,3,4,6-pentagalloyl-beta-D-glucopyranose (PGG) (compound I). The isolated anticoagulant significantly prolonged the activated partial thrombin time (APTT) and thrombin time (TT) using normal human plasma. One microgram of 1,2,3,4,6-pentagalloyl-beta-D-glucopyranose showed 0.063 heparin units in the APTT and 2.73 heparin units in the TT for anti-thrombosis. This is the first report of the isolation of PGG from geranium plants.     

Free radical scavenging activity and antiproliferative potential of <Emphasis Type="Italic">Polygonum cuspidatum</Emphasis> root extracts

Polygonum cuspidatum is widely used as a medicinal herb in Asia. In this study, ethanol and ethyl acetate extracts of P. cuspidatum root were assayed for their 1,1-diphenyl-2-hydrazyl (DPPH) and hydroxyl free radical scavenging activities, total phenolics content, protective effect against DNA damage, and antiproliferative activity on human lung cancer cells. The ethanol and ethyl acetate (lipophilic phase) extracts of P. cuspidatum had significant scavenging effects on DPPH and hydroxyl radicals. Total phenolics content of ethanol and ethyl acetate (lipophilic phase) extracts of P. cuspidatum were 276.78 ± 39.31 and 231.73 ± 5.04 mg/ml, respectively; both extracts protected against hydroxyl radical-induced DNA strand scission. Furthermore, the extracts of P. cuspidatum induced apoptosis and inhibited cell growth in A549 and H1650 cell lines, suggesting that P. cuspidatum root extracts exhibit an antiproliferative effect on human lung cancer cells.     

苏木提取液对胃癌细胞增殖及凋亡作用的研究

目的探讨苏木提取液对人胃癌细胞株SGC-7901的生长抑制及凋亡作用。方法采用细胞计数法绘制生长曲线检测苏木提取液对SGC-7901细胞的生长抑制作用;苏木素-伊红(HE)及荧光染色观察用药后细胞的形态学变化;琼脂糖凝胶电泳检测DNA梯形。结果生长曲线提示苏木提取液对SGC-7901细胞有明显的生长抑制作用;形态学观察可见典型的细胞凋亡特征,如细胞核固缩、染色质凝聚及凋亡小体形成,且药物作用呈现一定的浓度依赖性;琼脂糖凝胶电泳可见典型的DNA梯形。结论苏木提取液对人胃癌细胞株SGC-7901有明显的生长抑制及诱导凋亡的作用。     

Inhibitory effects on the digestive enzyme alpha-amylase of three Salsola species (Chenopodiaceae) in vitro

Hypoglycaemic effects of Salsola kali, S. soda, and S. oppositifolia (Chenopodiaceae) aerial parts were examined using in vitro assay based on the inhibition of a-amylase. The S. kali ethyl acetate fraction was the most active with a C1050 value 0.022 mg/ml. Through bioassay-guided fractionation processes two flavonol glycosides, isorhamnetin-3-O-glucoside and isorhamnetin-3-O-rutinoside, were isolated by silica gel column chromatography and characterized by spectroscopic methods. Isorhamnetin-3-O-rutinoside showed an interesting activity (IC50 0.129 mM).     

Antibacterial activity of Thai herbal extracts on acne involved microorganism

Ethyl acetate and methanol extracts of 18 Thai medicinal plants were investigated for their antibacterial activity against Propionibacterium acnes, Stapylococcus aureus, and S. epidermidis. Thirteen plant extracts were capable of inhibiting the growth of P. acnes and S. epidermidis, while 14 plant extracts exhibited an inhibitory effect on S. aureus. Based on the broth dilution method, the ethyl acetate extract of Alpinia galanga (L.) Wild. (Zingiberaceae) rhizome showed the strongest antibacterial effect against P. acnes, with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 156.0 and 312.0 µg/mL, respectively. On the basis of bioassay-guided purification, the ethyl acetate extract was isolated to afford the antibacterial active compound, which was identified as 1′-acetoxychavicol acetate (1′-ACA). 1′-ACA had a strong inhibitory effect on P. acnes with MIC and MBC values of 62.0 and 250.0 µg/mL, respectively. Thus, 1′-ACA was used as an indicative marker for standardization of A. galanga extract using high performance liquid chromatography. These results suggest that A. galanga extract could be an interesting agent for further studies on an alternative treatment of acne.     

Studies on cytotoxic, hydroxyl radical scavenging and topoisomerase inhibitory activities of extracts of Tabernaemontana divaricata (L.) R.Br. ex Roem. and Schult

In the present investigation, the cytotoxic, hydroxyl radical scavenging and topoisomerase inhibition activities of Tabernaemontana divaricata (Apocynaceae) were evaluated. The extracts from leaves of the plant were prepared with different solvents viz. chloroform, methanol, ethyl acetate and hexane. In, in vitro cytotoxicity assay, with cell lines viz HCT-15 (Colon), HT-29 (Colon), 502713 (Colon), MCF-7 (Breast), PC- 3 (Prostrate), it was observed that the ethyl acetate extract was effective against only one colon cell line (502713) at the lowest dose i.e. 10 micro g/ml, whereas the chloroform extract was effective against all the three colon cancer cell lines, at 30 microg/ ml. In order to evaluate the mechanism of cytotoxicity of these extracts, they were assessed for their ability to scavenge hydroxyl radicals in plasmid nicking assay with pBR322. It was observed that all the extracts effectively inhibited the unwinding of supercoiled DNA except hexane extract, which showed the least effect. Since the expression of topo enzymes is linked with cell proliferation so the extracts were also checked for topo I and topo II inhibitory activities. It was noticed that ethyl acetate extract selectively showed inhibition of topo II in topoisomerase II relaxation assay.     

Human epithelial carcinoma cytotoxicity and inhibition of DMBA/TPA induced squamous cell carcinoma in Balb/c mice by Acacia catechu heartwood

Objectives Acacia catechu heartwood contains significant amounts of polyphenolic compounds that exhibit powerful antioxidant activity. The purpose of this study was to evaluate the cytotoxicity of A. catechu heartwood extracts in a human epithelial carcinoma cell line (A431) and antitumour activity against DMBA/TPA induced squamous cell carcinoma in Balb/c mice. Methods Various extracts, including aqueous, ethyl acetate, chloroform and n‐hexane, were tested for cytotoxic properties on a human epithelial carcinoma cell line (A431) by using MTT, sulforhodamine B and lactate dehydrogenase leakage assays. The standardized A. catechu heartwood aqueous extract (AQCE) was further evaluated for antitumour activity against 7,12‐dimethylbenz[a]anthracene (DMBA)/12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) induced skin carcinoma in Balb/c mice. Key findings The results showed that administration of AQCE showed a dose‐dependent growth inhibition response, with an IC50 value of 78.56 µg/ml. Tumour incidence was significantly decreased (P < 0.001) to 30% with AQCE compared with 100% in the DMBA/TPA group. The AQCE was also found to significantly upregulate different antioxidant enzymes in skin and liver tissue. Conclusions The results suggest that AQCE may exert its chemopreventive activity by acting as an antioxidant.     

Platelet-activating factor (PAF) receptor binding activity of the roots of Enicosanthellum pulchrum

Context: Enicosanthellum pulchrum (King) Heusden (Annonaceae) is a coniferous tree that is confined to mountain forests. The chemical constituents of this species have been studied previously; however, its biological activity has never been investigated before and is reported here for the first time.

Objective: The extracts, fractions and compounds from the roots of E. pulchrum were investigated for their inhibitory effects on platelet-activating factor (PAF) receptor binding to rabbit platelets using ³H-PAF as a ligand.

Materials and methods: The PAF receptor binding inhibitory effect using rabbit platelets was determined in vitro by measuring the difference between total amount of bound ³H-PAF in the presence and the absence of excess unlabelled PAF. The compounds were isolated by bioassay-guided fractionation and their structures were elucidated by spectroscopic techniques.

Results and discussion: Among the extracts tested, the ethyl acetate extract was the most active with 85.6% inhibition, while hexane and methanol extracts showed 40.2 and 42.5% inhibition, respectively. Fractionation of the ethyl acetate extract using vacuum liquid chromatography (VLC) yielded six fractions AEA(I-–VI). Chromatography fraction AEA(VI) yielded a new compound, 1-(2′,3′,4′-trimethoxyphenyl)hexan-1-ol, while fraction AEA(III) afforded three compounds, namely liriodenine, cleistopholine and dehydroanonaine. 1-(2′,3′,4′-Trimethoxyphenyl)hexan-1-ol, cleistopholine and dehydroanonaine showed relatively strong inhibition with IC₅₀ values of 26.6, 50.2 and 45.4 µM, respectively.

Conclusion: The results suggest that these compounds could be responsible for the PAF antagonistic activity of the ethyl acetate extract of this plant.     

Anticonvulsive activity of Butea monosperma flowers in laboratory animals

The bioassay-guided fractionation of dried flowers of Butea monosperma (BM) was carried out to isolate the active principle responsible for its anticonvulsant activity. The petroleum ether extract was fractionated by column chromatography using solvents of varying polarity such as n-hexane, n-hexane:ethyl acetate, ethyl acetate, and methanol. The anticonvulsive principle of B. monosperma was found to be a triterpene (TBM) present in the n-hexane:ethyl acetate (1:1) fraction of the petroleum ether extract. TBM exhibited anticonvulsant activity against seizures induced by maximum electroshock (MES) and its PD(50) was found to be 34.2+/-18.1 mg/kg. TBM also inhibited seizures induced by pentylenetetrazol (PTZ), electrical kindling, and the combination of lithium sulfate and pilocarpine nitrate (Li-Pilo). However, TBM was not effective against seizures induced by strychnine and picrotoxin. TBM exhibited depressant effect on the central nervous system. After repeated use for 7 days, the PD(50) (MES) of TBM increased to 51.5+/-12.1 mg/kg. Similarly, after repeated use of TBM, the duration of sleep induced by pentobarbital was not reduced significantly. Further studies are required to investigate its usefulness in the treatment of epilepsy.     

Cytotoxic activities of hexane, ethyl acetate and butanol extracts of marine sponges from Mauritian Waters on human cancer cell lines

The ocean is an exceptional source of natural products with many of them exhibiting novel structural features and bioactivity. As one of the most interesting phylum with respect to pharmacological active marine compounds, Poriferas have been investigated widely in the last few decades. A total of 60 organic extracts (hexane, ethyl acetate and butanol) from 20 species of marine sponges from Mauritius were screened at 50μg/ml in an in vitro screening assay against 9 human cancer cell lines. From these tested extracts, many exhibited pronounced cytotoxic effect at least in one of the cell lines and cell type cytotoxic specificity was observed. 27% of ethyl acetate, 11% of hexane and 2% of butanol extracts were found to possess a cytotoxicity ≥75% on 9 different cancer cell lines with the sponges Petrosia sp. 1, Petrosia sp. 2, Pericharax heteroraphis and Jaspis sp. being the most active. Overall, the HL-60cells were much more sensitive to most of the extracts than the other cell lines. We further evaluated the properties of the ethyl acetate (JDE) and hexane extract (JDH) of one sponge, Jaspis sp. on KB cells. JDE displayed a smaller IC(50) than JDH. Clonogenic assay confirmed the antiproliferative effect of both extracts while mitochondrial membrane potential change and microscopic analysis demonstrated extracts-induced apoptosis. Treatment with 100ng/ml of JDE led to a significant increase of cells (24h: 4.02%; 48h: 26.23%) in sub-G1 phase. The cytotoxic properties of the tested extracts from these sponges suggest the presence of compounds with pharmacological potential and are currently undergoing fractionation to isolate the active constituents.     

Isolation of a multidrug resistance inhibitor fromAconitum pseudo-laeve var.erectum

To overcome multidrug resistance (MDR) in cancer chemotherapy, we prepared various plant extracts and searched for a component which is effective for inhibition of MDR. MDR inhibition activity was determined by measuring cytotoxicity to MDR cells using multidrug resistant human fibrocarcinoma KB V20C, which is resistant to 20 nM vincristine and expresses high level ofmdr1 gene. Of various plant extracts, the MeOH extract of the root ofAconitum pseudo-laeve var.erectum was found to have potent inhibitory activity on MDR. The bioassay-guided fractionation of the MeOH extract of the plant led to the isolation of an alkaloid, lycaconitine, as an active principle. And the IC₅₀ of lycaconitne for KB V20C cells was 74 μg/ml.     

Cytotoxic constituents of the octocoralDendronephthya gigantea

A known monoalkyl glycerol ether, (+/-)-1-nonadecyloxy-2,3-propanediol (1) was isolated from the ethyl acetate extract of a soft coral Dendronephthya gigantea as a weakly cytotoxic constituent against four human cancer cell lines, A549, HT-29, HT-1080, and SNU-638. In addition, a known ceramide, (2S,3R,4E,8E)-N-hexadecanoyl-2-amino-4,8-octadecadiene-1,3-diol (2), was also isolated as an inactive constituent. This is the first report on the isolation of the compounds 1 and 2 from the octocoral, Dendronephthya species.     

Inhibitory effects of constituents of <Emphasis Type="Italic">Morinda citrifolia</Emphasis> seeds on elastase and tyrosinase

A 50% ethanolic extract (MCS-ext) from seeds of Morinda citrifolia (“noni” seeds) showed more potent in vitro inhibition of elastase and tyrosinase, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity than extracts of M. citrifolia leaves or flesh. Activity-guided fractionation of MCS-ext using in vitro assays led to the isolation of ursolic acid as an active constituent of elastase inhibitory activity. 3,3′-Bisdemethylpinoresinol, americanin A, and quercetin were isolated as active constituents having both tyrosinase inhibitory and radical scavenging activities. Americanin A and quercetin also showed superoxide dismutase (SOD)-like activity. These active compounds were isolated from noni seeds for the first time.     

In vivo anti-inflammatory and antinociceptive effects of liriodendrin isolated from the stem bark of Acanthopanax senticosus

In the present study, liriodendrin isolated by activity-guided fractionation from the ethyl acetate (EtOAc) extracts of the stem bark of Acanthopanax senticosus, was evaluated for anti-inflammatory and antinociceptive activities. Liriodendrin (5, 10 mg/kg/day, p. o.) significantly inhibited the increase of vascular permeability induced by acetic acid in mice and reduced an acute paw edema induced by carrageenan in rats. When the analgesic activity was measured by the acetic acid-induced writhing test and hot plate test, liriodendrin showed a dose-dependent inhibition in animal models. In addition, syringaresinol, the hydrolysate of liriodendrin, more potently inhibited the LPS-induced production of NO, PGE 2 and TNF-alpha production of macrophages than liriodendrin. Consistent with these observations, the expression level of iNOS and COX-2 enzyme was decreased by syringaresinol in a concentration-dependent manner. These results suggest that the anti-inflammatory and antinociceptive effects of liriodendrin after oral administration were attributable to the in vivo transformation to syringaresinol, which may function as the active constituent.