Mechanism of antimutagenicity of aquatic plant extracts against benzo[a]pyrene in the Salmonella assay

The mechanism of antimutagenicity of water extracts of grass-wrack pondweed (Potamogeton oxyphylus Miquel), curled pondweed (Potamogeton crispus L.) and smartweed (Polygonum hydropiper L.) towards benzo[a]pyrene mutagenicity in Salmonella typhimurium was investigated. The antimutagenic components in the aquatic plants were water-soluble, heat-resistant and had a high molecular weight; chlorophyll did not play an important role.     

Antioxidative and free radical scavenging activities of selected medicinal herbs

The antioxidative and superoxide- and hydroxyl radical-scavenging activities and pro-oxidant effect of twelve selected medicinal herbs were studied. The aqueous extracts of Coptis chinensis, Paeonia suffruticosa, Prunella vulgaris and Senecio scandens exhibited the highest potency in inhibiting rat erythrocyte hemolysis and lipid peroxidation in rat kidney and brain homogenates. The aforementioned four herbs also demonstrated strong superoxide- and hydroxyl radical-scavenging activity, but exerted only a slight pro-oxidant effect.     

Antimutagenic effects of natural phenolic compounds in beans

Polyphenols in fruits, vegetables (e.g., flavonols like quercetin) and tea (e.g., catechins such as epigallocatechin gallate) are good antioxidants with antimutagenic and anticarcinogenic properties. In the present study, the Salmonella typhimurium tester strain YG1024 was used in the plate-incorporation test to examine the antimutagenic effect of phenolic compounds, extracted from common beans (Phaseolus vulgaris), on 1-NP and B[a]P mutagenicity. Dose-response curves for 1-NP and B[a]P were obtained; the number of net revertants/plate at the peak mutagenic dosage were 880 for 1-NP and 490 for B[a]P. For the antimutagenicity studies doses of 0.1 microg/plate and 2 microg/plate for 1-NP and B[a]P, respectively, were chosen. We obtained a dose-response curve of ellagic acid (EA) against B[a]P and 1-NP mutagenicity. To test the bean extract, a dose of 300 microg/plate of EA was chosen as the antimutagenic control. The EA and bean extracts were not toxic to the bacteria at the concentrations tested. The inhibitory effects of the bean extracts and EA against B[a]P mutagenicity were dose-dependent. The percentages of inhibition produced against B[a]P (2 microg/plate) using 300 microg/plate of EA and for the extracts 500 microg equivalent catechin/plate were 82%, 83%, 81% and 83% for EA, water extract, water/methanol extract and methanol extract, respectively. However, for 1-NP mutagenicity, only the methanolic extract from beans showed an inhibitory effect. These results suggest that common beans, as other legumes, can function as health-promoting foods.     

Antimutagenicity studies of chlorophyllin using the Salmonella arabinose-resistant assay system

Studies with the arabinose-resistant Salmonella forward mutation assay system were performed to determine the antimutagenic activity of chlorophyllin against the mutagenic activity of aflatoxin B1 (AFB1), 2-aminoanthracene (2AA), benzo[a]pyrene (BaP), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and solvent extracts of coal dust (CD), diesel emission particles (DE), airborne particles (AP), tobacco snuff (TS), black pepper (BP) and red wine (RW). Various concentrations of each chemical and complex mixture extract were assayed for mutagenic activity with and/or without S9 in a preincubation test. One concentration of each chemical and complex mixture extract was then tested with various concentrations of chlorophyllin. Results showed that chlorophyllin, at concentrations of 2.5 mg/plate or less, completely or almost completely inhibited the mutagenicity of 2AA, AFB1, BaP, MNNG and solvent extracts of CD, DE and RW. With concentrations from 1.25 to 5 mg/plate, chlorophyllin inhibited over 50% of the mutagenicity of AP, TS and BP extracts. These results further substantiate the antimutagenic efficacy of chlorophyllin against chemicals and complex mixtures.     

Antimutagenic effects of mushrooms

A heat-resistant factor in ethanol extracts of the fungus Craterellus cornucopioides completely inhibited the mutagenicity of aflatoxin B1, benzo[a]pyrene, the acridine half mustard ICR-191 and 2-nitrofluorene in a forward-mutation system using Salmonella typhimurium TM677 (screening for 8-azaguanine resistance). There was no inhibitory effect on the mutagenic activity of 4-nitroquinoline-N-oxide, methyl methanesulfonate or N-methyl-N'-nitro-N-nitrosoguanidine. Experiments performed to elucidate the mechanism of the antimutagenic effect showed that neither an alteration of cell viability nor an interference with the excision-repair and the inducible SOS-repair system was involved. The conceivable mechanisms for the antimutagenicity of the ethanol extract include direct chemical interaction with the mutagen and/or inhibition of the activation process in the case of the promutagens. The antimutagenic activity of Craterellus cornucopioides is not unique among mushroom species. The ethanol extracts of 6 other mushrooms showed a similar antimutagenic activity.     

Degradation of Polycyclic Aromatic Hydrocarbons by Crude Extracts from Spent Mushroom Substrate and its Possible Mechanisms

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by pure laccase has been reported, but the high cost limited its application in environmental bioremediation. Here, we reported a study about PAHs degradation by crude extracts (CEs) containing laccase, which were obtained by extracting four spent mushroom (Agaricus bisporus, Pleurotus eryngii, Pleurotus ostreatus, and Coprinus comatus) substrates. The results showed that anthracene, benzo[a]pyrene, and benzo[a]anthracene were top three degradable PAHs by CEs while naphthalene was most recalcitrant. The PAHs oxidation was enhanced in the presence of 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Laccase included in CE might play a major role in PAHs degradation. The maximum degradation rate of anthracene and benzo[a]pyrene was observed by using crude extracts from P. eryngii while the highest laccase activities were found in crude extracts from A. bisporus, moreover, crude extracts from P. eryngii, which contained less laccase activities, degraded more anthracene and benzo[a]pyrene than pure laccase with higher laccase activities. The lack of correlation between laccase activity and PAHs degradation rate indicated that other factors might also influence the PAHs degradation. Boiled CEs were added to determine the effect on PAHs degradation by laccase. The results showed that all four boiled CEs had improved the PAHs oxidation. The maximum improvement was observed by adding CEs from P. eryngii. It suggested that some mediators indeed existed in CEs and CEs from P. eryngii contained most. As a result, CEs from P. eryngii has the most application potential in PAHs bioremediation.     

Effects of medicinal plant extracts from Chinese herbal medicines on the mutagenic activity of benzo[a]pyrene

The effects of medicinal plants on the mutagenicity of benzo[a]pyrene were studied with Salmonella typhimurium tester strains. The chosen medicinal plants are very frequently used as Chinese herbal medicines. Each medicinal plant was extracted with hot water, which is similar to the method used in Chinese medicinal treatment. Cinnamomi cortex, Rhei rhizoma, Scutellariae radix and Rehmanniae radix were found to decrease the mutagenic activity of benzo[a]pyrene. Atractylodis rhizoma also reduced the mutagenicity of benzo[a]pyrene, but this was not certain, because it showed a killing effect on the cell survival test. Bupleuri radix and Aurantii nobilis pericarpium had an enhancing effect, but then neither of these extracts is itself mutagenic. Each medicinal plant extract showed a different effect on the mutagenicity of benzo[a]pyrene. These effects were classified into 5 types: (I) decreasing effect, (II) killing effect, (III) enhancing effect, (IV) enhancing and decreasing effect and (V) inactive.     

Oxidation of polycyclic aromatic hydrocarbons by the bacterial laccase CueO from E. coli

Laccases produced by white rot fungi are capable of rapidly oxidizing benzo[a]pyrene. We hypothesize that the polycyclic aromatic hydrocarbon (PAH)-degrading bacteria producing laccase can enhance the degree of benzo[a]pyrene mineralization. However, fungal laccases are glycoproteins which cannot be glycosylated in bacteria, and there is no evidence to show that bacterial laccases can oxidize benzo[a]pyrene. In this study, the in vitro oxidation of PAHs by crude preparations of the bacterial laccase, CueO, from Escherichia coli was investigated. The results revealed that the crude CueO catalyzed the oxidation of anthracene and benzo[a]pyrene in the same way as the fungal laccase from Trametes versicolor, but showed specific characteristics such as thermostability and copper dependence. In the presence of 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid), high amounts of anthracene and benzo[a]pyrene, 80% and 97%, respectively, were transformed under optimal conditions of 60°C, pH 5, and 5 mmol l(-1) CuCl(2) after a 24-h incubation period. Other PAHs including fluorene, acenaphthylene, phenanthrene, and benzo[a]anthracene were also oxidized by the crude CueO. These findings indicated the potential application of prokaryotic laccases in enhancing the mineralization of benzo[a]pyrene by PAH-degrading bacteria.     

Production of nitric oxide, tumor necrosis factor-alpha and interleukin-6 by RAW264.7 macrophage cells treated with lactic acid bacteria isolated from kimchi

The multistage induction theory is generally regarded as the mechanism of carcinogenesis. In order to prevent the initiation stage of carcinogenesis, it is meaningful to discover the functional components of edible plants. The objective of this research was to test the antimutagenicity of the functional components of several typical traditional herbs used in Japan. The traditional herbs, gennoshoko (Geranium nepalense var. thunbergii), yomogi (Artemisia vulgaris var. indica), senburi (Swertia japonica), iwa-tobacco (Conandron ramondioides), sarunokoshikake (Elfvingia applanata), kanzo (Glycyeehiza uralensis Fisch) and matatabi (Actinidia polygama) were examined by Ames mutagenesis assay test with Salmonella typhimurium TA98 and TA100 against mutagens, Trp-P-1, Trp-P-2 and B(a)P. The water-soluble components or volatile oil of the herbs were extracted in boiling water. The extracts of gennoshoko showed strong antimutagenicity against B(a)P with S. typhimurium TA98 and TA100, as well as Trp-P-1 and Trp-P-2 with S. typhimurium TA98. Yomogi, senburi and iwa-tobacco were also proved to have good antimutagenicity against Trp-P-1 and Trp-P-2 with S. typhimurium TA98, but weaker antimutagenicity against B(a)P. Other herbs did not show any obvious antimutagenicity against these mutagens. In addition, the volatile oil of yomogi also had remarkable antimutagenic effect against the mutagens we used with S. typhimurium TA98.     

Inhibitory effect of Teucrium ramosissimum extracts on aflatoxin B1, benzo[a]pyrene, 4-nitro-o-phenylenediamine and sodium azide induced mutagenicity: Correlation with antioxidant activity

The mutagenic potential of total oligomers flavonoids (TOF), ethyl acetate (EA) and petroleum ether (PE) extracts from aerial parts of Teucrium ramosissimum was assessed using Ames Salmonella tester strains TA98, TA100 and TA1535 with and without metabolic activation (S9). None of the different extracts produced a mutagenic effect. Likewise, the antimutagenicity of the same extracts was tested using the “Ames test”. Our results showed that T. ramosissimum extracts possess antimutagenic activity against all the tested genotoxicants (aflatoxin B₁, benzo[a]pyrene, 4-nitro-o-phenylenediamine and sodium azide) in the Salmonella assay systems used in this study. In addition, all extracts showed important free radical scavenging activity toward the radicals DPPH and ABTS except the PE extract.     

中草药浸提液对小列当种子发芽的影响

选用240种常用中草药,研究其蒸馏水和甲醇浸提液原液及其10倍、100倍和1 000倍稀释液对小列当种子发芽的影响.结果表明:小列当种子在蒸馏水浸提液刺激下发芽率超过70%的中草药有灯心草、降香和莲须,在甲醇浸提液刺激下发芽率超过70%的中草药有百部、桑椹、谷芽和萆薢;蒸馏水浸提液对小列当种子发芽抑制率超过50%的中草药有菊花、棕榈、苦杏仁和黄柏,甲醇浸提液对小列当种子发芽抑制率超过70%的有续断、地黄、肉豆蔻、地肤子、黄连、木贼和胡黄连.大部分中草药浸提液在10倍稀释液条件下对小列当种子发芽的刺激或抑制作用最明显.研究发现,一些参试中草药蒸馏水和甲醇浸提液能够刺激或抑制小列当种子萌发,并且其对种子萌发的影响程度随浸提液浓度的变化而异,不同中草药最佳处理浓度不同,而且用甲醇浸提液可筛选出更多种具有化感作用的中草药.     

Blocking of cell proliferation, cytokines production and genes expression following administration of Chinese herbs in the human mesangial cells.

In the hope of identifying agents of therapeutic value in immuoglobulin A nephropathy (IgA-N), we tested crude methanol extracts of 15 Chinese herbs for their effect on human mesangial cell proliferation. The results indicated that 4 out of the 15 crude extracts inhibited human cells proliferation activated by IL-1beta and IL-6. The extracts and their median inhibitory concentrations were as follows (in microg/ml): Ludwiga octovalvis (MLS-052), 49.9 +/- 1.8; Rhus semialata (MLS-053), 31.2 +/- 1.6; Tabernaemontana divaricata (MLS-054), 50.0 +/- 2.1; Amepelopsis brevipedunculata (MLS-059), 42.9 +/- 1.1. These findings indicate that human mesangial cells were most sensitive to MLS-053 treatment. These herbs also decreased interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) production. Moreover, IL- 1beta mRNA expression was inhibited by Rhus semialata (R. semialata; MLS-053). It is unlikely that cytotoxicity was involved, because no cell deaths were observable. We hypothesize that the inhibitory mechanisms of these Chinese herbs may be related to the impairments of gene expression and production of cytokines in human mesangial cells. Plans are underway for the isolation of pure compounds from these Chinese herbs and the elucidation of their mechanisms of action.     

Importance of the route of administration for genetic differences in benzo[a]pyrene-induced in utero toxicity and teratogenicity

C57BL/6N (Ahb/Ahb) mice have a high-affinity Ah receptor in tissues, whereas AKR/J and DBA/2N (Ahd/Ahd) mice have a poor-affinity Ah receptor. The cytochrome P1-450 induction response (enhanced benzo[a]pyrene metabolism) occurs much more readily in Ahb/Ahb and Ahb/Ahd than in Ahd/Ahd mice, at any given dose of the inducer benzo[a]pyrene. Embryos from the AKR/J X (C57BL/6N)(AKR/J)F1 and the reciprocal backcross were studied during benzo[a]pyrene feeding of the pregnant females. Oral benzo[a]pyrene (120 mg/kg/day) given to pregnant Ahd/Ahd mice between gestational day 2 and 10 produces more intrauterine toxicity and malformations in Ahd/Ahd than Ahb/Ahd embryos. This striking allelic difference is not seen in pregnant Ahb/Ahd mice receiving oral benzo[a]pyrene. Pharmacokinetics studies with [3H]benzo[a]pyrene in the diet and high-performance liquid chromatographic analysis of benzo[a]pyrene metabolism in vitro by the maternal intestine, liver, and ovary and the embryos of control and oral benzo[a]pyrene-treated pregnant females are consistent with "first-pass elimination" kinetics and differences in benzo[a]pyrene metabolism by the embryos and/or placentas versus maternal tissues. In the pregnant Ahd/Ahd mouse receiving oral benzo[a]pyrene, little induction of benzo[a]pyrene metabolism occurs in her intestine and liver; this leads to much larger amounts of benzo[a]pyrene reaching her embryos, and genetic differences in toxicity and teratogenesis are manifest. In the pregnant Ahb/Ahd mouse receiving oral benzo[a]pyrene, benzo[a]pyrene metabolism is greatly enhanced in her intestine and liver; this leads to less benzo[a]pyrene reaching her embryos, much less intrauterine toxicity and malformations, and no genetic differences are manifest. More toxic metabolites (especially benzo[a]pyrene 1,6- and 3,6-quinones) are shown to occur in Ahd/Ahd embryos than in Ahb/Ahd embryos. In additional studies, no prenatal or neonatal "imprinting" effect in C57BL/6N mice by 2,3,7,8-tetrachlorodibenzo-p-dioxin or Aroclor 1254 on benzo[a]pyrene metabolism later in life was detectable. These genetic differences in intrauterine toxicity and teratogenicity induced by oral benzo[a]pyrene are just opposite those induced by intraperitoneal benzo[a]pyrene [Shum et al., '79; Hoshino et al., '81). The data in the present report emphasize the importance of the route of administration when the teratogen induces its own metabolism.     

Degradation and mineralization of high-molecular-weight polycyclic aromatic hydrocarbons by defined fungal-bacterial cocultures

This study investigated the biodegradation of high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) in liquid media and soil by bacteria (Stenotrophomonas maltophilia VUN 10,010 and bacterial consortium VUN 10,009) and a fungus (Penicillium janthinellum VUO 10, 201) that were isolated from separate creosote- and manufactured-gas plant-contaminated soils. The bacteria could use pyrene as their sole carbon and energy source in a basal salts medium (BSM) and mineralized significant amounts of benzo[a]pyrene cometabolically when pyrene was also present in BSM. P. janthinellum VUO 10,201 could not utilize any high-molecular-weight PAH as sole carbon and energy source but could partially degrade these if cultured in a nutrient broth. Although small amounts of chrysene, benz[a]anthracene, benzo[a]pyrene, and dibenz[a,h]anthracene were degraded by axenic cultures of these isolates in BSM containing a single PAH, such conditions did not support significant microbial growth or PAH mineralization. However, significant degradation of, and microbial growth on, pyrene, chrysene, benz[a]anthracene, benzo[a]pyrene, and dibenz[a,h]anthracene, each as a single PAH in BSM, occurred when P. janthinellum VUO 10,201 and either bacterial consortium VUN 10,009 or S. maltophilia VUN 10,010 were combined in the one culture, i.e., fungal-bacterial cocultures: 25% of the benzo[a]pyrene was mineralized to CO(2) by these cocultures over 49 days, accompanied by transient accumulation and disappearance of intermediates detected by high-pressure liquid chromatography. Inoculation of fungal-bacterial cocultures into PAH-contaminated soil resulted in significantly improved degradation of high-molecular-weight PAHs, benzo[a]pyrene mineralization (53% of added [(14)C]benzo[a]pyrene was recovered as (14)CO(2) in 100 days), and reduction in the mutagenicity of organic soil extracts, compared with the indigenous microbes and soil amended with only axenic inocula.     

The antioxidative activity of traditional Japanese herbs

The objective of this research was to examine the radical scavenging activity of traditional Japanese herbs. Samples used in the experiments were gennoshoko (Geranium nepalense var. thunbergii), yomogi (Artemisia vulgaris var.indica), senburi (Swertia japonica), iwa-tobacco (Conandron ramondioides), sarunokoshikake (Elfvingia applanata), kanzo (Glycyrrhiza uralensis Fisch) and matatabi (Actinidia polygama). The water-soluble components of the herbs were extracted in boiling water, and the volatile oil was extracted by a distillation apparatus or steeping in some organic solvents such as petroleum ether and ethyl ether. The radical scavenging activity was determined by the decrease of free radicals of DPPH detected by both colorimetric assay and HPLC method at 517 nm. The extracts of gennoshoko, yomogi and iwa-tobacco showed remarkable radical scavenging activity. The volatile oil of yomogi obtained by distillation or steeping in organic solvents had especially strong antioxidative activity.     

Effect of vitamins A, C and glutathione on the mutagenicity of benzo[a]pyrene mediated by S9 from vitamin A-deficient rats

Vitamin A deficiency has been shown to enhance the mutagenicity of benzo[a]pyrene (Narbonne et al., 1985). Here we report that this is not a result of increased benzo[a]pyrene metabolism but might be a consequence of either a lack of vitamin A or a decreased level of scavengers (ascorbic acid and glutathione) in the liver. However, the addition of vitamin A in vitro in the form of retinyl palmitate strongly inhibits the benzo[a]pyrene mutagenicity. An enhancing effect on the mutagenicity of benzo[a]pyrene is observed with addition of ascorbic acid when incubated with high amounts of the precarcinogen. In vivo addition of high levels of glutathione also reduces the mutagenicity of benzo[a]pyrene.     

Neonatal modulation of adult rat hepatic microsomal benzo[a]pyrene hydroxylase activities by Aroclor 1254 or phenobarbital

The constitutive and Aroclor 1254-induced activities of hepatic microsomal benzo[a]pyrene hydroxylases in male and female rats were determined in animals from ages 11 to 120 days. In 11-day-old noninduced male rats, benzo[a]pyrenediones and 9-hydroxybenzo[a]pyrene were the major microsomal metabolites; in 21-day-old males benzo[a]pyrene-diones and benzo[a]pyrene-9,10-dihydrodiol were predominant. In 60- and 120-day-old animals 3-hydroxybenzo[a]pyrene was the major microsomal metabolite. A similar trend was observed for the development of benzo[a]pyrene hydroxylase activities in female rats. With the exception of 4,5-dihydrodiol formation, the highest induction of individual and total benzo[a]pyrene hydroxylase activities by Aroclor 1254 was observed in the 21-day-old immature male rats, in which there was a 330- and 4.5-fold increase in the formation of 3-hydroxybenzo[a]pyrene and quinone metabolites, respectively. The induction of benzo[a]pyrene total metabolite formation by Aroclor 1254 in female rats from 11 to 120 days of age was relatively constant (i.e., 13.3- to 10.1-fold induction); however, the relative induction of the individual benzo[a]pyrene hydroxylases was highly variable. In a second set of experiments, male and female rats were neonatally exposed to phenobarbital (600 mumol/kg) or Aroclor 1254 (100 mumol/kg), and the effects of these xenobiotics on neonatal imprinting of hepatic microsomal benzo[a]pyrene hydroxylase activities were determined in the 120-day-old animals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Aryl hydrocarbon receptor-mediated activity of mutagenic polycyclic aromatic hydrocarbons determined using in vitro reporter gene assay

Activation of aryl hydrocarbon receptor (AhR) by 30 polycyclic aromatic hydrocarbons (PAHs) was determined in the chemical-activated luciferase expression (CALUX) assay, using two exposure times (6 and 24h), in order to reflect the metabolization of PAHs. AhR-inducing potencies of PAHs were expressed as induction equivalency factors (IEFs) relative to benzo[a]pyrene and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In 24h exposure assay, the highest IEFs were found for benzo[k]fluoranthene, dibenzo[a,h]anthracene and dibenzo[a,k]fluoranthene (approximately three orders of magnitude lower than TCDD) followed by dibenzo[a,j]anthracene, benzo[j]fluoranthene, indeno[1,2,3-cd]pyrene, and naphtho[2,3-a]pyrene. The 6h exposure to PAHs led to a significantly higher AhR-mediated activity than the 24h exposure (generally by two orders of magnitude), probably due to the high rate of PAH metabolism. The strongest AhR inducers showed IEFs approaching that of TCDD. Several PAHs, including some strong mutagens, such as dibenzo[a,l]pyrene, cyclopenta[cd]pyrene, and benzo[a]perylene, elicited only partial agonist activity. Calculation of IEFs based on EC25 values and/or 6h exposure data is suggested as an alternative approach to estimation of toxic potencies of PAHs with high metabolic rates and/or the weak AhR agonists. The IEFs, together with the recently reported relative mutagenic potencies of PAHs [Mutat. Res. 371 (1996) 123; Mutat. Res. 446 (1999) 1] were combined with data on concentrations of PAHs in extracts of model environmental samples (river sediments) to calculate AhR-mediated induction equivalents and mutagenic equivalents. The highest AhR-mediated induction equivalents were found for benzo[k]fluoranthene and benzo[j]fluoranthene, followed by indeno[1,2,3-cd]pyrene, dibenzo[a,h]anthracene, benzo[a]pyrene, dibenzo[a,j]anthracene, chrysene, and benzo[b]fluoranthene. High mutagenic equivalents in the river sediments were found for benzo[a]pyrene, dibenzo[a,e]pyrene, and naphtho[2,3-a]pyrene and to a lesser extent also for benzo[a]anthracene, benzo[b]fluoranthene, indeno[1,2,3-cd]pyrene, benzo[j]fluoranthene, dibenzo[a,e]fluoranthene and dibenzo[a,i]pyrene. These data illustrate that AhR-mediated activity of PAHs, including the highly mutagenic compounds, occurring in the environment but not routinely monitored, could significantly contribute to their adverse effects.     

9种植物水浸提液对空心莲子草的化感作用

【背景】空心莲子草是难以防除的恶性入侵杂草,因此,探索高效无毒的化感防治方法具有重要意义。【方法】利用水浸提法研究了博落回、苦瓜、樟树、柳杉、凤尾蕨、柑橘、夹竹桃、洋葱及大蒜9种植物不同器官对空心莲子草的化感作用。【结果】与对照相比,博落回叶、苦瓜果肉与种子、凤尾蕨、樟树叶和柳杉叶的水浸提液对空心莲子草具有较强的化感作用,主要表现为空心莲子草叶片数和茎节数减少,株高与生物量的增长受到抑制。【结论与意义】不同植物水浸提液对空心莲子草的化感作用有所差异。本研究为利用植物的化感作用控制空心莲子草提供了依据。     

A comparison of HIV-1 integrase inhibition by aqueous and methanol extracts of Chinese medicinal herbs

The aqueous and methanol extracts of twenty herbs traditionally used in Chinese medicine were screened for anti-HIV-1 integrase activity in a non-radioactive ELISA-based HIV-1 integrase assay. The screening was performed at an herb extract concentration of 50 microg/ml. It was found that most of the aqueous and methanol herb extracts could elicit strong inhibition of HIV-I integrase activity. The inhibition was most likely due to tannins or polyphenolics in the herb extracts. In most of the herb extracts, 40-80% of the anti-HIV-1 integrase activity could be removed after passing through a minicolumn of polyamide resin. After removal of polyphenolic compounds, the methanol extract of Paeonia suffruticosa still exerted potent inhibition of HIV-1 integrase (EC50 = 15 microg/ml) and the aqueous extract of Prunella vulgaris caused moderate inhibition (EC50 = 45 microg/ml). The results support the view that herbs represent a rich source of anti-HIV compounds.