Aqueous Extracts Of Medicinal Plants Research Articles

Effects of aqueous extracts of medicinal plants on MNNG-treated rat hepatocytes in primary cultures

Aqueous extracts of Nigella sativa (Ranunculaceae) (Ns), Teucrium polium (Labiatae) (Tp) and Trigonella foenum-graecum (Fabaceae) (Tf) have been traditionally used to treat inflammations, liver disorders, and arthritis. Experimentally, it has been demonstrated that these herbs possess antioxidant, anti-inflammatory and hepatoprotective properties. To evaluate their in vitro toxicological properties and potential antimutagenic effects aqueous extracts of the three plants were tested in primary rat hepatocyte cultures against N-methyl- N′-nitro- N-nitrosoguanidine. The extracts were applied before, during and after application of MNNG to discriminate between different mechanisms of action. Tp itself significantly increased apoptosis, but in the combined treatment with MNNG significantly reduced it. Post-treatment with Ns or combined treatment with Tf significantly reduced the percentages of necrotic cells. The three plant extracts themselves significantly increased the frequency of chromosomal aberrations. Summarizing, our results suggest that aqueous extracts of the three herbs have neither cytoprotective nor antimutagenic activity, instead there is evidence for a mutagenic potential.

Mutagenic and antimutagenic potential of the medicinal plants M. laevigata and C. xanthocarpa.

Aqueous extracts of medicinal plants (Mikania laevigata and Campomanesia xanthocarpa) were screened for the presence of mutagenic activity in the Salmonella/microsome assay. The extracts of Campomanesia xanthocarpa showed frameshift (TA97a strain) signs of mutagenic activity without exogenous metabolism (S9 fraction). The infusions of Mikania laevigata, negative for mutagenic activity, showed high percentages of inhibition of mutagenesis induced by mutagens 2AF (2-amino fluorene), in the presence of exogenous metabolism (S9 fraction), for frameshift (TA98) and base pair substitution (TA100) lesions. In addition, these inhibitions were observed against mutagen SAZ (sodium azide) in assays with the TA100 strain, without exogenous metabolism (S9 fraction). A synergistic effect was also observed in frameshift mutagenic events, with direct action in the presence of 4NQO (4-oxide-1-nitroquinoline) and a tendency to a low percentage of action enhancement, in the presence of the 2AF mutagen. The variable responses observed in the extract assays show the potentials for interaction of the different active principles in genetic material.

Effect of aqueous extracts of medicinal plants on growth of Fusarium moniliforme var subglutinans Wollenw. and Reinking.

The growth of Fusarium moniliforme var subglutinans Wollenw. and Reinking was evaluated in chloramphenicol potato dextrose agar (cPDA) containing 20 %aqueous extractsof eight medicinal plants. Mycelia growth, was reduced in unautoclaved extracts of Cassia alata, Baphia nitida, Euphorbia hirta, Vernonia amygdalina, Azadirachta indica, and Zingiber officinale, with B. nitida, V. amygdalina, and C. alata, being the most effective. On the contrary, the unautoclaved extract of Cyathula prostrata did not affect the growth of the fungus. The antifungal activities of B. nitida, A. indica, E. hirta, Z. officinale, and C. alata were affected by autoclave treatment. Unautoclaved extracts of C. alata, B. nitida, A. indica, V. amygdalina, A. cordifolia, E. hirta and Z. officinale significantly (p£0.05) reduced the dry weight of the fungus below the control. Autoclaving the extracts affected the fungitoxic activities of C. alata, B. nitida, and V. amygdalina, on the dry weight of the fungus. Sporulation was completely inhibited in cPDA medium amended with unautoclaved extracts of C. alata, B. nitida, A. indica, V. amygdalina and Z. officinale. However all the autoclaved extracts supported sporulation of the fungus. Conidia germination in full strength (w/v, 1:1) extracts was completely inhibited, whereas 90 % of the conidia germinated in sterile deionised water after 6 h of incubation. These findings suggest the potential role of the extracts in controlling the fungus. Keywords: Fusarium moniliforme var subglutinans, medicinal plants, aqueous extracts, in vitro growth inhibition. [Global Jnl Agric Res Vol.2(1) 2003: 9-16]

Mutagenicity of medicinal plant extracts in­Salmonella/microsome assay

Aqueous extracts of medicinal plants used in south Brazilian folk medicine (Myrciaria tenella, Smilax campestris, Tripodanthus acutifolius and Cassia corymbosa) were screened for the presence of mutagenic activity in the Salmonella/microsome assay. Signs of an increased mutagenic induction below revertant rates, which is two times the spontaneous yields, were detected for all extracts. The extracts of C. corymbosa showed signs of mutagenic activity in the following strains: TA100 with and without metabolization and TA98 after metabolization. These mutagenic signs were observed in the M. tenella extracts without metabolization. S. campestris and T. acutifolius infusions also showed signs indicative of direct mutagenic activity in the TA98 strain. The positive results may be related to the presence of flavonoids, tannins and anthraquinones in the extracts.

Mutagenicity of medicinal plant extracts in Salmonella/microsome assay.

Aqueous extracts of medicinal plants used in south Brazilian folk medicine (Myrciaria tenella, Smilax campestris, Tripodanthus acutifolius and Cassia corymbosa) were screened for the presence of mutagenic activity in the Salmonella/microsome assay. Signs of an increased mutagenic induction below revertant rates, which is two times the spontaneous yields, were detected for all extracts. The extracts of C. corymbosa showed signs of mutagenic activity in the following strains: TA100 with and without metabolization and TA98 after metabolization. These mutagenic signs were observed in the M. tenella extracts without metabolization. S. campestris and T. acutifolius infusions also showed signs indicative of direct mutagenic activity in the TA98 strain. The positive results may be related to the presence of flavonoids, tannins and anthraquinones in the extracts.

Effect on cell surface hydrophobicity and susceptibility of Helicobacter pylori to medicinal plant extracts.

Effects on aqueous extracts of medicinal plants on ten Helicobacter pylori strains were studied by the salt aggregation test to determine the possibility to modulate their cell surface hydrophobicity and by an agar diffusion assay for detection of antimicrobial activity. It was established that aqueous extracts of bearberry and cowberry leaves enhance cell aggregation of all H. pylori strains tested by the salt aggregation test, and the extract of bearberry possessed a remarkable bacteriostatic activity. Pure tannic acid showed a result similar to that of bearberry and cowberry extracts which contained a large amount of tannins. In contrast, extracts of wild camomile and pineapple-weed, which blocked aggregation of H. pylori, contained small amounts of tannins and did not reveal any antimicrobial activity. Tannic acid seems to be the component of bearberry and cowberry aqueous extracts with the highest activity to decrease cell surface hydrophobicity as well as in antibacterial activity against H. pylori.

Effect on cell surface hydrophobicity and susceptibility of Helicobacter pylori to medicinal plant extracts

Effects of aqueous extracts of medicinal plants on ten Helicobacter pylori strains were studied by the salt aggregation test to determine the possibility to modulate their cell surface hydrophobicity and by an agar diffusion assay for detection of antimicrobial activity. It was established that aqueous extracts of bearberry and cowberry leaves enhance cell aggregation of all H. pylori strains tested by the salt aggregation test, and the extract of bearberry possessed a remarkable bacteriostatic activity. Pure tannic acid showed a result similar to that of bearberry and cowberry extracts which contained a large amount of tannins. In contrast, extracts of wild camomile and pineapple-weed, which blocked aggregation of H. pylori, contained small amounts of tannins and did not reveal any antimicrobial activity. Tannic acid seems to be the component of bearberry and cowberry aqueous extracts with the highest activity to decrease cell surface hydrophobicity as well as in antibacterial activity against H. pylori.

Influence of aqueous extracts of medicinal plants on surface hydrophobicity of Escherichia coli strains of different origin

The adhesion of microbes on host cells is of decisive importance in the development of Gram-negative microbe-induced infections and can be influenced by the surface hydrophobicity of the microbial cell. The hydrophobicity of 155 Escherichia coli strains of different origin was determined by the salt aggregation test (SAT). Among the strains isolated from faecal samples of healthy persons only 16.7% showed aggregative properties, whereas among the strains isolated from the urine of patients with pyelonephritis and the faecal samples of calves and pigs with diarrhoea some 40.0%-60.0% were aggregative. The influence of aqueous extracts prepared from bearberry leaves, St. John's wort herbs, wild camomile and marigold flowers on hydrophobicity of 40 E. coli and 20 Acinetobacter baumannii strains was investigated. The decoctions of bearberry and St. John's wort increased remarkably the hydrophobicity of both microbial species. The infusions of wild camomile and marigold completely blocked the aggregative properties of the investigated strains. Bactericidal action was relatively low in the case of bearberry and St. John's wort and completely lacking in the case of wild camomile and marigold. Thus, one of the probable and potentially important action mechanisms of the four medicinal plants studied is their ability to influence the surface characteristics of the microbial cells and thereby their putative virulence properties.

Preliminary Screening of Medicinal Plants for Biological Activity Based on Inhibition of Cyclic AMP Phosphodiesterase

Hot aqueous extracts of medicinal plants were tested for their inhibitory effect on phosphodiesterase. Of 33 samples tested, six showed reproducible inhibition. The cyclic AMP phosphodiesterase inhibitor contained in Coptis teeta was identified as berberine.

Platelet activating factor (PAF) antagonists contained in medicinal plants: lignans and sesquiterpenes.

Hot aqueous extracts of medicinal plants were tested for their inhibitory effect on the binding of platelet activating factor (PAF) to rabbit platelets. The extracts of Forsythia suspensa VAHL. (Oleaceae), Arctium lappa L. (Compositae) and Centipeda minima (L.) A. BRAUN et ASCHERS (Compositae) showed significant activities. Since the main constituents of F. suspensa and A. lappa are lignans, 30 lignans were tested for their inhibitory effects on PAF binding to platelets and 9 lignans were found active. Four sesquiterpenes were isolated as active compounds from C. minima. In particular 6-O-angeloylplenolin and 6-O-senecioyplenolin are the most potent and specific PAF antagonists found in this study.

Inhibition of prostaglandin biosynthesis by the constituents of medicinal plants.

Hot aqueous extracts of medicinal plants used in oriental medicine were tested for inhibitory effect on prostaglandin biosynthesis in order to detect biologically active compounds present therein. Of 162 samples tested, 35 showed significant inhibition. Inhibitors of prostaglandin biosynthesis contained in Cyperus rotundus were identified as sesquiterpenes. α-Cyperone, the main inhibitor of C. rotundus, showed competitive-type inhibition with respect to the substrate, arachidonic acid.

Inhibitors of cyclic AMP phosphodiesterase in medicinal plants.

Hot aqueous extracts of medicinal plants used in oriental medicine were tested for their inhibitory effect on beef heart phosphodiesterase to detect biologically active compounds present therein. Of 222 samples tested 22 showed reproducible inhibition. cAMP phosphodiesterase inhibitors contained in Anemarrhena asphodeloides were identified as norlignans and their structure activity relationship was investigated; cis-hinokiresinol, the main inhibitor exhibited a prolongation effect on hexobarbital sleeping time in mice.