Herbal Science Research - in vitro

Human hair growth enhancement in vitro by green tea epigallocatechin-3-gallate (EGCG).

Site Editor — Wed, 26 Sep 2007 18:49:37 -0700

Human hair growth enhancement in vitro by green tea epigallocatechin-3-gallate (EGCG).: Phytomedicine. 2007 Aug;14(7-8):551-5 Authors: Kwon OS, Han JH, Yoo HG, Chung JH, Cho KH, Eun HC, Kim KH

Green tea is a popular worldwide beverage, and its potential beneficial effects such as anti-cancer and anti-oxidant properties are believed to be mediated by epigallocatechin-3-gallate (EGCG), a major constituent of polyphenols. Recently, it was reported that EGCG might be useful in the prevention or treatment of androgenetic alopecia by selectively inhibiting 5alpha-reductase activity. However, no report has been issued to date on the effect of EGCG on human hair growth. This study was undertaken to measure the effect of EGCG on hair growth in vitro and to investigate its effect on human dermal papilla cells (DPCs) in vivo and in vitro. EGCG promoted hair growth in hair follicles ex vivo culture and the proliferation of cultured DPCs. The growth stimulation of DPCs by EGCG in vitro may be mediated through the upregulations of phosphorylated Erk and Akt and by an increase in the ratio of Bcl-2/Bax ratio. Similar results were also obtained in in vivo dermal papillae of human scalps. Thus, we suggest that EGCG stimulates human hair growth through these dual proliferative and anti-apoptotic effects on DPCs.

PMID: 17092697 [PubMed - indexed for MEDLINE]

Effect of valerian, valerian/hops extracts, and valerenic acid on glucuronidation in vitro.

Site Editor — Wed, 06 Jun 2007 00:10:24 -0700

Effect of valerian, valerian/hops extracts, and valerenic acid on glucuronidation in vitro.: Xenobiotica. 2007 Feb;37(2):113-23 Authors: Alkharfy KM, Frye RF

Valerian preparations alone or in combination with hops are popular over-the-counter products used for sleep disturbances or anxiety. Therefore, it is important to characterize the effect of these products on the activity of human drug-metabolizing enzymes. The inhibitory effects of valerian and valerian/hops extracts as well as valerenic acid (a major constituent of valerian) on glucuronidation were evaluated in human liver microsomes and with expressed uridine 5'-diphosphate (UDP)-glucuronosyltransferases (UGT). Methanolic extracts of two herbal preparations caused significant reductions in the rate of formation of acetaminophen, oestradiol, morphine, and testosterone glucuronides. Oestradiol glucuronidation at the 3-hydroxy position was inhibited by nearly 87% in microsomal incubations. In addition, marked reductions in UGT1A1 and UGT2B7 activities were observed in the presence of the herbal extracts using oestradiol and morphine as probe substrates, respectively. Valerenic acid also demonstrated significant inhibitory effects on the glucuronidation of acetaminophen, oestradiol, and morphine with both microsomes and expressed UGTs. The relatively low IC50 values obtained for valerenic acid in microsomal incubations may indicate that this essential oil contributes to the effects observed with herbal extracts in inhibiting glucuronidation in vitro. Overall, these findings suggest that valerian-containing products may interfere with the glucuronidation of endo- and xenobiotics.

In vitro and in vivo anti-retroviral activity of the substance purified from the aqueous extract of Chelidonium majus L.

Site Editor — Fri, 19 Jan 2007 18:37:20 -0800

In vitro and in vivo anti-retroviral activity of the substance purified from the aqueous extract of Chelidonium majus L.: Antiviral Res. 2006 Nov;72(2):153-6 Authors: Gerencer M, Turecek PL, Kistner O, Mitterer A, Savidis-Dacho H, Barrett NP

We have isolated a substance with anti-retroviral activity from the freshly prepared crude extract of Chelidonium majus L. (greater celandine) by 9-aminoacridine precipitation method and ion exchange chromatography using Dowex-50W/H+ resin followed by the gel filtration on Sephadex-75 column. Elemental and phenol/sulfuric acid method analyses as well as the mass spectrometry of the purified substance indicated that it may represent a low-sulfated poly-glycosaminoglycan moiety with molecular weight of approximately 3800 Da. The substance prevented infection of human CD4+ T-cell lines AA2 and H9 with HIV-1 at concentration of 25 microg/mL as well as the cell-to-cell virus spread in H9 cells continuously infected with HIV-1, as determined by the measurement of reverse transcriptase activity and p24 content in cell cultures. Furthermore, we have shown in a murine AIDS model that the treatment with purified substance significantly prevented splenomegaly and the enlargement of cervical lymph nodes in C57Bl/6 mice chronically infected with the pool of murine leukemia retroviruses. The mechanism(s) of anti-retroviral activity of this substance have to be elucidated.

Analysis of the interaction of phytoestrogens and synthetic chemicals: An in vitro/in vivo comparison.

Site Editor — Wed, 17 Jan 2007 06:32:55 -0800

Analysis of the interaction of phytoestrogens and synthetic chemicals: An in vitro/in vivo comparison.: Toxicol Appl Pharmacol. 2006 Dec 5; Authors: Charles GD, Gennings C, Tornesi B, Kan HL, Zacharewski TR, Bhaskar Gollapudi B, Carney EW

In the evaluation of chemical mixture toxicity, it is desirable to develop an evaluation paradigm which incorporates some critical attributes of real world exposures, particularly low dose levels, larger numbers of chemicals, and chemicals from synthetic and natural sources. This study evaluated the impact of low level exposure to a mixture of six synthetic chemicals (SC) under conditions of co-exposure to various levels of plant-derived phytoestrogen (PE) compounds. Estrogenic activity was evaluated using an in vitro human estrogen receptor (ER) transcriptional activation assay and an in vivo immature rat uterotrophic assay. Initially, dose-response curves were characterized for each of the six SCs (methoxyclor, o,p-DDT, octylphenol, bisphenol A, beta-hexachlorocyclohexane, 2,3-bis(4-hydroxyphenyl)-propionitrile) in each of the assays. The six SCs were then combined at equipotent ratios and tested at 5-6 dose levels spanning from very low, sub-threshold levels, to a dose in which every chemical in the mixture was at its individual estrogenic response threshold. The SC mixtures also were tested in the absence or presence of 5-6 different levels of PEs, for a total of 36 (in vitro) or 25 (in vivo) treatment groups. Both in vitro and in vivo, low concentrations of the SC mixture failed to increase estrogenic responses relative to those induced by PEs alone. However, significant increases in response occurred when each chemical in the SC mixture was near or above its individual response threshold. In vitro, interactions between high-doses of SCs and PEs were greater than additive, whereas mixtures of SCs in the absence of PEs interacted in a less than additive fashion. In vivo, the SC and PE mixture responses were consistent with additivity. These data illustrate a novel approach for incorporating key attributes of real world exposures in chemical mixture toxicity assessments, and suggest that chemical mixture toxicity is likely to be of concern only when the mixture components are near or above their individual response thresholds. However, these data suggest that extrapolation from in vitro assays to in vivo mixture effects should be approached with caution.

In vitro antibacterial activity of some plant essential oils.

Site Editor — Tue, 09 Jan 2007 06:09:51 -0800

In vitro antibacterial activity of some plant essential oils.:
BMC Complement Altern Med. 2006;6:39 Authors: Prabuseenivasan S, Jayakumar M, Ignacimuthu S

BACKGROUND: To evaluate the antibacterial activity of 21 plant essential oils against six bacterial species. METHODS: The selected essential oils were screened against four gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus vulgaris) and two gram-positive bacteria Bacillus subtilis and Staphylococcus aureus at four different concentrations (1:1, 1:5, 1:10 and 1:20) using disc diffusion method. The MIC of the active essential oils were tested using two fold agar dilution method at concentrations ranging from 0.2 to 25.6 mg/ml. RESULTS: Out of 21 essential oils tested, 19 oils showed antibacterial activity against one or more strains. Cinnamon, clove, geranium, lemon, lime, orange and rosemary oils exhibited significant inhibitory effect. Cinnamon oil showed promising inhibitory activity even at low concentration, whereas aniseed, eucalyptus and camphor oils were least active against the tested bacteria. In general, B. subtilis was the most susceptible. On the other hand, K. pneumoniae exhibited low degree of sensitivity. CONCLUSION: Majority of the oils showed antibacterial activity against the tested strains. However Cinnamon, clove and lime oils were found to be inhibiting both gram-positive and gram-negative bacteria. Cinnamon oil can be a good source of antibacterial agents.

In vitro determination of the contraceptive spermicidal activity of a composite extract of Achyranthes aspera and Stephania...

Site Editor — Thu, 05 Oct 2006 18:37:40 -0700

In vitro determination of the contraceptive spermicidal activity of a composite extract of Achyranthes aspera and Stephania hernandifolia on human semen.: Contraception. 2006 Mar;73(3):284-8 Authors: Paul D, Bera S, Jana D, Maiti R, Ghosh D

OBJECTIVE: To evaluate the effect of a 50% ethanolic extract of the leaf of Stephania hernandifolia and the root of Achyranthes aspera on sperm motility and function in a ratio of 1:3 by weight at different concentrations. RESULTS: Concentration of 0.08 g/mL of the extract affected the motility, and at a concentration of 0.16 g/mL, the sperm motility was reduced to 20% immediately (within 20 s). At a concentration of 0.32 g/mL, this composite extract showed the most promising results by complete sperm immobilization within 2 min after the application of the extract. The effects were spermicidal but not spermiostatic as sperm immobilization effect was found to be irreversible. Sperm viability was decreased significantly and was found to be nonviable after 30 min when treated with the composite extract at a concentration of 0.32 g/mL. The hypo-osmotic swelling of these sperm was reduced significantly at this highest concentration, indicating that the crude extract may probably cause injury to the sperm plasma membrane. A low concentration of 0.04 g/mL is ineffective. CONCLUSION: The findings indicate that this composite plant extract possesses potential contraceptive spermicidal activity in vitro.

Effect of artemisinin/artesunate as inhibitors of hepatitis B virus production in an "in vitro" replicative system.

Site Editor — Fri, 09 Jun 2006 04:33:03 -0700

Effect of artemisinin/artesunate as inhibitors of hepatitis B virus production in an "in vitro" replicative system.: Antiviral Res. 2005 Nov;68(2):75-83 Authors: Romero MR, Efferth T, Serrano MA, Castaño B, Macias RI, Briz O, Marin JJ

The antiviral effect against hepatitis B virus (HBV) of artemisinin, its derivative artesunate and other compounds highly purified from traditional Chinese medicine remedies, were investigated. HBV production by permanently transfected HepG2 2.2.15 cells was determined by measuring the release of surface protein (HBsAg) and HBV-DNA after drug exposure (0.01-100 microM) for 21 days. The forms of HBV-DNA released were investigated by Southern-blotting. Neutral Red retention test was used to evaluate drug-induced toxicity on host cells. The compounds were classified according to their potential interest as follows: (i) none: they had no effect on viral production (daidzein, daidzin, isonardosinon, nardofuran, nardosinon, tetrahydronardosinon and quercetin); (ii) low: they were able to markedly reduce viral production, but also induced toxicity on host cells (berberine and tannic acid) or they had no toxic effect on host cells but only had a moderate ability to reduce viral production (curcumin, baicalein, baicalin, bufalin, diallyl disulphide, glycyrrhizic acid and puerarin); (iii) high: they induced strong inhibition of viral production at concentrations at which host cell viability was not affected (artemisinin and artesunate). Moreover, artesunate in conjunction with lamivudine had synergic anti-HBV effects, which warrants further evaluation of artemisinin/artesunate as antiviral agents against HBV infection.

Centella asiatica accelerates nerve regeneration...and contains multiple active fractions increasing neurite elongation in-vitro

Site Editor — Fri, 09 Jun 2006 04:19:46 -0700

Centella asiatica accelerates nerve regeneration upon oral administration and contains multiple active fractions increasing neurite elongation in-vitro.: J Pharm Pharmacol. 2005 Sep;57(9):1221-9 Authors: Soumyanath A, Zhong YP, Gold SA, Yu X, Koop DR, Bourdette D, Gold BG

Axonal regeneration is important for functional recovery following nerve damage. Centella asiatica Urban herb, also known as Hydrocotyle asiatica L., has been used in Ayurvedic medicine for centuries as a nerve tonic. Here, we show that Centella asiatica ethanolic extract (100 microg mL-1) elicits a marked increase in neurite outgrowth in human SH-SY5Y cells in the presence of nerve growth factor (NGF). However, a water extract of Centella was ineffective at 100 microg mL-1. Sub-fractions of Centella ethanolic extract, obtained through silica-gel chromatography, were tested (100 microg mL-1) for neurite elongation in the presence of NGF. Greatest activity was found with a non-polar fraction (GKF4). Relatively polar fractions (GKF10 to GKF13) also showed activity, albeit less than GKF4. Thus, Centella contains more than one active component. Asiatic acid (AA), a triterpenoid compound found in Centella ethanolic extract and GKF4, showed marked activity at 1 microM (microg mL-1). AA was not present in GKF10 to GKF13, further indicating that other active components must be present. Neurite elongation by AA was completely blocked by the extracellular-signal-regulated kinase (ERK) pathway inhibitor PD 098059 (10 microM). Male Sprague-Dawley rats given Centella ethanolic extract in their drinking water (300-330 mg kg-1 daily) demonstrated more rapid functional recovery and increased axonal regeneration (larger calibre axons and greater numbers of myelinated axons) compared with controls, indicating that the axons grew at a faster rate. Taken together, our findings indicate that components in Centella ethanolic extract may be useful for accelerating repair of damaged neurons.

Neutralizing properties of Musa paradisiaca L. (Musaceae) juice on phospholipase A2, myotoxic, hemorrhagic and lethal activities

Site Editor — Fri, 09 Jun 2006 04:14:05 -0700

Neutralizing properties of Musa paradisiaca L. (Musaceae) juice on phospholipase A2, myotoxic, hemorrhagic and lethal activities of crotalidae venoms.: J Ethnopharmacol. 2005 Apr 8;98(1-2):21-9 Authors: Borges MH, Alves DL, Raslan DS, Piló-Veloso D, Rodrigues VM, Homsi-Brandeburgo MI, de Lima ME

The use of plants as medicine has been referred to since ancient peoples, perhaps as early as Neanderthal man. Plants are a source of many biologically active products and nowadays they are of great interest to the pharmaceutical industry. The study of how people of different culture use plants in particular ways has led to the discovery of important new medicines. In this work, we verify the possible activity of Musa paradisiaca L. (Musaceae) against the toxicity of snake venoms. Musa paradisiaca, an important source of food in the world, has also been reported to be popularly used as an anti-venom. Interaction of Musa paradisiaca extract (MsE) with snake venom proteins has been examined in this study. Phospholipase A2 (PLA2), myotoxic and hemorrhagic activities, including lethality in mice, induced by crotalidae venoms were significantly inhibited when different amounts of MsE were mixed with these venoms before assays. On the other hand, mice that received MsE and venoms without previous mixture or by separated routes were not protected against venom toxicity. Partial chemical characterization of MsE showed the presence of polyphenols and tannins and they are known to non-specifically inactivate proteins. We suggest that these compounds can be responsible for the in vitro inhibition of the toxic effects of snake venoms. In conclusion, according to our results, using mice as experimental model, MsE does not show protection against the toxic effects of snake venoms in vivo, but if was very effective when the experiments were done in vitro.

[Vitexicarpin, from Vitex trifolia L., induces apoptosis in K562 cells via mitochondria-controlled apoptotic pathway.]

Site Editor — Fri, 09 Jun 2006 04:05:52 -0700

[Vitexicarpin, a flavonoid from Vitex trifolia L., induces apoptosis in K562 cells via mitochondria-controlled apoptotic pathway]: Yao Xue Xue Bao. 2005 Jan;40(1):27-31 Authors: Wang HY, Cai B, Cui CB, Zhang DY, Yang BF

AIM: To investigate the inhibitory effect of vitexicarpin on the proliferation of human cancer cells and its mechanism of action. METHODS: The inhibitory effect of vitexicarpin on the proliferation of human cancer cells was evaluated by the SRB method and its apoptosis-inducing effect was demonstrated by morphological observation under light microscope, flow cytometric analysis and agarose gel electrophoresis. The proteins related to apoptosis were examined by Western blotting analysis. RESULTS: Vitexicarpin significantly inhibited the proliferation of human cancer cells, A2780, HCT-15, HT-1080 and K562, with the IC50 values of (19.1 +/- 2.4) micromol x L(-1) for A2780(48 h), (0.66 +/- 0.10) micromol x L(-1) for HCT-15(48 h), (0.44 +/- 0.06) micromol x L(-1) for HT-1080 (48 h) and (0.28 +/- 0.14) micromol x L(-1) for K562 (24 h). The cells treated with vitexicarpin showed characteristic morphology typical for apoptosis and gave dose-dependent sub-G0/G1 peak in the flow cytometric analysis and DNA ladder on agarose gel electrophoresis. In Western blotting analysis, the cleavage of PARP and caspase-3, the release of cytochrome c from mitochondria into the cytosol, the decrease of Bcl-2 expression level, and the down-regulation of the ratio of Bcl-2/Bax expression level were examined in the K562 cells treated with vitexicarpin. CONCLUSION: Vitexicarpin induces apoptosis in K562 cells via mitochondria-controlled apoptotic pathway.

Inhibition of uropathogenic Escherichia coli by cranberry juice: a new antiadherence assay.

Site Editor — Fri, 09 Jun 2006 04:05:29 -0700

Inhibition of uropathogenic Escherichia coli by cranberry juice: a new antiadherence assay.: J Agric Food Chem. 2005 Nov 16;53(23):8940-7 Authors: Turner A, Chen SN, Joike MK, Pendland SL, Pauli GF, Farnsworth NR

A combination of microplate technology and turbidity assessment for testing the adherence of P-fimbriated Escherichia coli to human uroepithelial cell line T24, validated with the addition of the known inhibitor 4-O-alpha-D-galactopyranosyl-alpha-D-galactopyranose (galabiose), resulted in a high-throughput, biologically relevant assessment of cranberry (Vaccinium macrocarpon). P-fimbriated ATCC E. coli strains 25922, 29194, and 49161 were inhibited by galabiose. ATCC 29194, a representative urine isolate containing the papGII allele (Class II fimbrial adhesin) and demonstrating the most significant inhibition in the presence of galabiose, was chosen for further testing. In this assay, a low-polarity fraction of cranberry juice cocktail demonstrated dose-dependent inhibition of E. coli adherence. Reported here, for the first time in V. macrocarpon, are 1-O-methylgalactose, prunin, and phlorizin, identified in an active fraction of cranberry juice concentrate. This in vitro assay will be useful for the standardization of cranberry dietary supplements and is currently being used for bioassay-guided fractionation of cranberry juice concentrate.

Inhibition of P-glycoprotein-mediated transport by extracts of and monoterpenoids contained in Zanthoxyli fructus.

Site Editor — Fri, 09 Jun 2006 03:59:43 -0700

Inhibition of P-glycoprotein-mediated transport by extracts of and monoterpenoids contained in Zanthoxyli fructus.: Toxicol Appl Pharmacol. 2005 Dec 1;209(2):167-73 Authors: Yoshida N, Takagi A, Kitazawa H, Kawakami J, Adachi I

Citrus (rutaceous) herbs are often used in traditional medicine and Japanese cuisine and can be taken concomitantly with conventional medicine. In this study, the effect of various citrus-herb extracts on P-glycoprotein (P-gp)-mediated transport was examined in vitro to investigate a possible interaction with P-gp substrates. Component monoterpenoids of the essential oil in Zanthoxyli fructus was screened to find novel P-gp inhibitors. LLC-GA5-COL150 cells transfected with human MDR1 cDNA encoding P-gp were used. Cellular accumulation of [3H]digoxin was measured in the presence or absence of P-gp inhibitors or test samples. Aurantii fructus, Evodiae fructus, Aurantii fructus immaturus, Aurantii nobilis pericarpium, Phellodendri cortex, and Zanthoxyli fructus were extracted with hot water (decocted) and then fractionated with ethyl acetate. The cell to medium ratio of [3H]digoxin accumulation increased significantly in the presence of the decoction of Evodiae fructus, Aurantii nobilis pericarpium, and Zanthoxyli fructus, and the ethyl acetate fraction of all citrus herbs used. The ethyl acetate fraction of Zanthoxyli fructus exhibited the strongest inhibition of P-gp among tested samples with an IC50 value of 166 microg/mL. Then its component monoterpenoids, geraniol, geranyl acetate, (R)-(+)-limonene, (R)-(+)-linalool, citronellal, (R)-(+)-citronellal, DL-citronellol, (S)-(-)-beta-citronellol, and cineole, were screened. (R)-(+)-citronellal and (S)-(-)-beta-citronellol inhibited P-gp with IC50 values of 167 microM and 504 microM, respectively. These findings suggest that Zanthoxyli fructus may interact with P-gp substrates and that some monoterpenoids with the relatively lower molecular weight of about 150 such as (R)-(+)-citronellal can be potent inhibitors of P-gp.

In vitro and in vivo antimicrobial action of tea: the commonest beverage of Asia.

Site Editor — Fri, 09 Jun 2006 03:47:44 -0700

In vitro and in vivo antimicrobial action of tea: the commonest beverage of Asia.: Biol Pharm Bull. 2005 Nov;28(11):2125-7 Authors: Bandyopadhyay D, Chatterjee TK, Dasgupta A, Lourduraja J, Dastidar SG

The methanolic extract of leaves of Camellia sinensis (L) O. KUNTZE was screened for antimicrobial property against 111 bacteria comprising 2 genera of Gram positive and 7 genera of Gram negative bacteria. Most of these strains were inhibited by the compound at 10-50 microg/ml level and few strains were sensitive even at lower concentrations (5 microg/ml). The bacteria could be arranged in the decreasing order of sensitivity towards the compound in the following manner: Staphylococcus aureus, Vibrio cholerae, Escherichia coli, Shigella spp., Salmonella spp., Bacillus spp., Klebsiella spp. and Pseudomonas aeruginosa. The antibacterial activity of compound could also be confirmed in vivo. When it was given to Swiss strain of white mice at different dosages (30, 60 microg/mouse), it could significantly protect the animals challenged with 50 MLD of Salmonella typhimurium NCTC 74. According to Chi square test the in vivo data were highly significant (p<0.001).

Natural products and the treatment of leukemia.

Site Editor — Fri, 09 Jun 2006 03:29:35 -0700

Natural products and the treatment of leukemia.: Leuk Res. 2005 Dec 5; Authors: Hamblin T

Plants have been the source of many medicines in the pharmacopoeia. So much so that an industry has arisen selling plant extracts as health foods. To a great degree it operates over the internet and it chiefly caters to the worried well. However, cancer patients frequently take plant extracts in addition to their prescribed medicines. These extracts are not biologically inactive, and many have important pro-apoptotic effects on cancer cell-lines in vitro. In this issue a study of the in vivo effects of green tea extract in low grade lymphomas is reported. The results are sufficiently encouraging to initiate a formal clinical trial.

Effects of single herbal drugs on adhesion and migration of melanocytes.

Site Editor — Fri, 09 Jun 2006 03:28:02 -0700

Effects of single herbal drugs on adhesion and migration of melanocytes.: J Tradit Chin Med. 2005 Sep;25(3):219-21 Authors: Zhang X, Feng J, Mu K, Ma H, Niu X, Liu C, Dang Q

OBJECTIVE: To find herbs with effects on adhesion and migration of melanocytes in vitro. MATERIALS AND METHODS: Ethanol extracts from 14 herbs were tested. Normal human melanocytes were obtained from neonatal foreskin, and the 48-well culture dish covered with fibronectin was used for the melanocyte adhesion assay. Motility was assessed by using the micropore filter method. RESULTS: The extracts of Danshen (Radix Salviae Miltiorrhizae), Tusizi (Semen Cuscutae) and Honghua (Flos Carthami) could enhance melanocyte adhesion to fibronectin, while Cijili (Fructus Tribuli) and Huangqi (Radix Astragali) promote melanocyte migration in vitro. Buguzhi (Fructus Psoraleae), Nü Zhen Zi (Fructus Ligustri Lucidi) and Baizhi (Radix Angelicae Dahuricae) could promote both adhesion and migration of melanocytes. CONCLUSION: The above herbs may play a role through promoting adhesion and/or migration of melanocytes in the treatment of vitiligo.

In vitro anti-HCV activities of Saxifraga melanocentra and its related polyphenolic compounds.

Site Editor — Fri, 09 Jun 2006 03:20:44 -0700

In vitro anti-HCV activities of Saxifraga melanocentra and its related polyphenolic compounds. Antivir Chem Chemother. 2005;16(6):393-8 Authors: Zuo GY, Li ZQ, Chen LR, Xu XJ

The aim of this study was to search for new natural anti-HCV agents from Chinese herbal medicine. Bioactivity-guided extraction and isolation methods were used. Active part and pure compounds were obtained from ethanolic extract of Saxifraga melanocentra Franch. and their in vitro inhibitory activities (IC50) against HCV NS3 serine protease were tested by enzyme-linked immunosorbent assay. Results showed that the polyphenolic ethyl acetate part of the herbal extract was the most active, and from this 18 polyphenols representing active compounds were isolated and identified. IC50 values of these compounds and five related ones were obtained. A broad-degree of anti-HCV activity was observed among them in the following order: gallated esters of D-glucose and rutin (0.68-4.86 microM)> flavonoids (33.11-370.37 microM)> gallic acid and its methyl and ethyl esters, Bergenin and others (over 1000 microM). The most active compound was 1,2,3,4,6-penta-O-galloyl-beta-D-glucoside (0.68 microM). In conclusion, polyphenols were responsible for the anti-HCV constitution of S. melanocentra, and multigallated esters of D-glucose possessed the strongest inhibition against HCV NS3 serine protease and little cytotoxic effect, suggesting the potential use of these compounds for designing and developing drugs for treatment of the viral infection.

In Vitro susceptibility of Helicobacter pylori to botanical extracts.

Site Editor — Fri, 09 Jun 2006 03:12:10 -0700

In Vitro susceptibility of Helicobacter pylori to botanical extracts used traditionally for the treatment of gastrointestinal disorders. - Phytother Res. 2005 Nov 29;19(11):988-991 Authors: Mahady GB, Pendland SL, Stoia A, Hamill FA, Fabricant D, Dietz BM, Chadwick LR

The gram-negative bacterium Helicobacter pylori (HP), identified in 1982, is now recognized as the primary etiological factor associated with the development of gastritis and peptic ulcer disease. In addition, HP infections are also associated with chronic gastritis, gastric carcinoma and primary gastric B-cell lymphoma. For centuries, herbals have been used in traditional medicine to treat a wide range of ailments, including gastrointestinal (GI) disorders such as dyspepsia, gastritis and peptic ulcer disease (PUD). However, the mechanism of action by which these botanicals exert their therapeutic effects has not been completely elucidated. As part of an ongoing screening program, the study assessed the in vitro susceptibility of 15 HP strains to botanical extracts, which have a history of traditional use in the treatment of GI disorders. Methanol extracts of Myristica fragrans (seed) had a MIC of 12.5 microg/mL; Zingiber officinale (ginger rhizome/root) and Rosmarinus officinalis (rosemary leaf) had an MIC of 25 microg/mL. Methanol extracts of botanicals with a MIC of 50 microg/mL included Achillea millefolium, Foeniculum vulgare (seed), Passiflora incarnata (herb), Origanum majorana (herb) and a (1:1) combination of Curcuma longa (root) and ginger rhizome. Botanical extracts with a MIC of 100 microg/mL included Carum carvi (seed), Elettaria cardamomum (seed), Gentiana lutea (roots), Juniper communis (berry), Lavandula angustifolia (flowers), Melissa officinalis (leaves), Mentha piperita (leaves) and Pimpinella anisum (seed). Methanol extracts of Matricaria recutita (flowers) and Ginkgo biloba (leaves) had a MIC > 100 microg/mL. Copyright (c) 2005 John Wiley & Sons, Ltd.

In vitro pharmacodynamic evaluation of antiviral medicinal plants using a vector-based assay technique.

Site Editor — Fri, 09 Jun 2006 03:11:29 -0700

In vitro pharmacodynamic evaluation of antiviral medicinal plants using a vector-based assay technique. - J Appl Microbiol. 2005;99(6):1346-55 Authors: Esimone CO, Grunwald T, Wildner O, Nchinda G, Tippler B, Proksch P, Uberla K

Aims: Medicinal plants are increasingly being projected as suitable alternative sources of antiviral agents. The development of a suitable in vitro pharmacodynamic screening technique could contribute to rapid identification of potential bioactive plants and also to the standardization and/or pharmacokinetic-pharmacodynamic profiling of the bioactive components. Methods and Results: Recombinant viral vectors (lentiviral, retroviral and adenoviral) transferring the firefly luciferase gene were constructed and the inhibition of viral vector infectivity by various concentrations of plant extracts was evaluated in HeLa or Hep2 cells by measuring the changes in luciferase activity. Cytotoxicity of the extracts was evaluated in parallel on HeLa or Hep2 cells stably expressing luciferase. Amongst the 15 extracts screened, only the methanol (ME) and the ethyl acetate (ET) fractions of the lichen, Ramalina farinacea specifically reduced lentiviral and adenoviral infectivity in a dose-dependent manner. Further, chromatographic fractionation of ET into four fractions (ET1-ET4) revealed only ET4 to be selectively antiviral with an IC(50) in the 20 mug ml(-1) range. Preliminary mechanistic studies based on the addition of the extracts at different time points in the viral infection cycle (kinetic studies) revealed that the inhibitory activity was highest if extract and vectors were preincubated prior to infection, suggesting that early steps in the lentiviral or adenoviral replication cycle could be the major target of ET4. Inhibition of wild-type HIV-1 was also observed at a 10-fold lower concentration of the extract. Conclusions: The vector-based assay is a suitable in vitro pharmacodynamic evaluation technique for antiviral medicinal plants. The technique has successfully demonstrated the presence of antiviral principles in R. farinacea. Significance and Impact of Study: Potential anti-HIV medicinal plants could rapidly be evaluated with the reported vector-based technique. The lichen, R. farinacea could represent a lead source of antiviral substances and is thus worthy of further studies.

Dietary flavonoids: Effects on xenobiotic and carcinogen metabolism.

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Dietary flavonoids: Effects on xenobiotic and carcinogen metabolism. - Toxicol In Vitro. 2005 Nov 10; Authors: Moon YJ, Wang X, Morris ME

Flavonoids are present in fruits, vegetables and beverages derived from plants (tea, red wine), and in many dietary supplements or herbal remedies including Ginkgo Biloba, Soy Isoflavones, and Milk Thistle. Flavonoids have been described as health-promoting, disease-preventing dietary supplements, and have activity as cancer preventive agents. Additionally, they are extremely safe and associated with low toxicity, making them excellent candidates for chemopreventive agents. The cancer protective effects of flavonoids have been attributed to a wide variety of mechanisms, including modulating enzyme activities resulting in the decreased carcinogenicity of xenobiotics. This review focuses on the flavonoid effects on cytochrome P450 (CYP) enzymes involved in the activation of procarcinogens and phase II enzymes, largely responsible for the detoxification of carcinogens. A number of naturally occurring flavonoids have been shown to modulate the CYP450 system, including the induction of specific CYP isozymes, and the activation or inhibition of these enzymes. Some flavonoids alter CYPs through binding to the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, acting as either AhR agonists or antagonists. Inhibition of CYP enzymes, including CYP 1A1, 1A2, 2E1 and 3A4 by competitive or mechanism-based mechanisms also occurs. Flavones (chrysin, baicalein, and galangin), flavanones (naringenin) and isoflavones (genistein, biochanin A) inhibit the activity of aromatase (CYP19), thus decreasing estrogen biosynthesis and producing antiestrogenic effects, important in breast and prostate cancers. Activation of phase II detoxifying enzymes, such as UDP-glucuronyl transferase, glutathione S-transferase, and quinone reductase by flavonoids results in the detoxification of carcinogens and represents one mechanism of their anticarcinogenic effects. A number of flavonoids including fisetin, galangin, quercetin, kaempferol, and genistein represent potent non-competitive inhibitors of sulfotransferase 1A1 (or P-PST); this may represent an important mechanism for the chemoprevention of sulfation-induced carcinogenesis. Importantly, the effects of flavonoids on enzymes are generally dependent on the concentrations of flavonoids present, and the different flavonoids ingested. Due to the low oral bioavailability of many flavonoids, the concentrations achieved in vivo following dietary administration tend to be low, and may not reflect the concentrations tested under in vitro conditions; however, this may not be true following the ingestion of herbal preparations when much higher plasma concentrations may be obtained. Effects will also vary with the tissue distribution of enzymes, and with the species used in testing since differences between species in enzyme activities also can be substantial. Additionally, in humans, marked interindividual variability in drug-metabolizing enzymes occurs as a result of genetic and environmental factors. This variability in xenobiotic metabolizing enzymes and the effect of flavonoid ingestion on enzyme expression and activity can contribute to the varying susceptibility different individuals have to diseases such as cancer. As well, flavonoids may also interact with chemotherapeutic drugs used in cancer treatment through the induction or inhibition of their metabolism.