The antimutagenic activity of biomass extracts from the cultured cells of medicinal plants in the Ames test

Antimutagenic activity of 20 and 40% ethanol extracts from the biomass of Rhodiola rosea, Polyscias filicifolia, Panax ginseng and Ungernia victoris cultured cells have been studied. DDDTDP, ethidium bromide, benz(a)pyrene, benzidine served as model mutagens for Salmonella typhimurium TA 98 strain (the latter two were tested in presence of metabolic activation system); for S. typhimurium TA 100 strain these were tio-tefa, bichromate potassium and sodium azide and heavy metal compounds (chlorides of manganese, zinc, cadmium, lead acetate) for both strains. Higher capacity of the extracts from the biomass of R. rosea and P. filicifolia to counteract gene mutations induced by various mutagens was demonstrated (ca. 90% inhibition in isolated cases). In the experiment with the metabolic activation most effective proved to be the extracts from the P. ginseng biomass (up to 34% and 47% mutagenicity inhibition).     

Screening of certain medicinal plants from India for their anti-quorum sensing activity

Discovery of quorum sensing (QS) system to coordinate virulence and biofilm formation in bacterial pathogens has triggered search for safe, stable and non-toxic anti-QS compounds from natural products. Ethanolic extracts of 24 Indian medicinal plants were tested by agar well and disc diffusion assay for anti-QS activity using Chromobacterium violaceum (CV12472 and CVO26) reporter strains. AHL from C. violaceum CV31532 was isolated and partially purified for its use in CVO26 based bioassay. Effect on swarming-motility of Pseudomonas aeruginosa (PAO1) was also recorded at sub-MIC concentrations of extracts. Of the 24 medicinal plants screened Hemidesmus indicus (L.) Schult (root), Holarrhena antidysenterica (Roth) A.DC. (bark), Mangifera indica L. (seed) Punica granatum L. (pericarp) and Psoralea corylifolia L. (seed) demonstrated varying level of inhibition of violacein production in the reporter strains. Moreover, a significant reduction in swarms was recorded over control. The inhibition of violacein production and swarming motility may be due to direct or indirect interference on QS by active constituents or the interactive effect of different phytocompounds present in the extracts. These plant extracts may be selected for activity guided fractionation to identify and characterize the active principle.     

Immune system and antioxidants,especially those derived from Indian medicinal plants

During the functioning of the immune system, such as in phagocytosis, reactive oxygen and nitrogen species are generated. If they are left unchecked they can affect the components of the immune system by inducing oxidative damage. This is more so in the elderly or during inflammation where there is excess generation of these reactive species than can be taken care of by the defenses in the form of antioxidants. Dietary supplementation with antioxidants may greatly help in such conditions. There are some indications of possible benefits of antioxidant supplementation. Natural compounds from medicinal plants having antioxidant and immunomodulatory activities have potential as therapeutic agents in this regard. Indian medicinal plants with these activities have been identified and their antioxidant and immunomodulatory effects reviewed. The possible future prospects in this regard are also outlined.     

Screening of anti-Helicobacter pylori herbs deriving from Taiwanese folk medicinal plants

In this study, extracts from 50 Taiwanese folk medicinal plants were examined and screened for anti-Helicobacter pylori activity. Ninety-five percent ethanol was used for herbal extraction. Paederia scandens (Lour.) Merr. (PSM), Plumbago zeylanica L. (PZL), Anisomeles indica (L.) O. Kuntze (AIOK), Bombax malabaricum DC. (BMDC) and Alpinia speciosa (J. C. Wendl.) K. Schum. (ASKS) and Bombax malabaricum DC. (BMDC) all demonstrated strong anti-H. pylori activities. The minimum inhibitory concentration values of the anti-H. pylori activity given by the five ethanol herb extracts ranged from 0.64 to 10.24 mg ml(-1). Twenty-six herbs, including Artemisia argvi Levl. et Vant (AALEV), Phyla nodiflora (Linn.) Greene (PNG) and others, showed moderate anti-H. pylori activity. The additional 19 herbs, including Areca catechu Linn. (ACL), Euphorbia hirta Linn. (EHL) and Gnaphalium adnatum Wall. ex DC. (GAWEDC), possessed lower anti-H. pylori effects. About half of the Taiwanese folk medicinal plants tested, demonstrated to possess higher anti-H. pylori activity.     

Screening of Korean medicinal plants for possible osteoclastogenesis effects in vitro

Bone undergoes continuous remodeling through bone formation and resorption, and maintaining the balance for skeletal rigidity. Bone resorption and loss are generally attributed to osteoclasts. Differentiation of osteoclasts is regulated by receptor activator of nuclear factor NF-kB ligand (RANKL), a member of tumor necrosis factor family. When the balance is disturbed, pathological bone abnormality ensues. Through the screening of traditional Korean medicinal plants, the effective molecules for inhibition and stimulation of RANKL-induced osteoclast differentiation in mouse bone marrow macrophages were identified. Among 222 methanol extracts, of medicinal plants, 10 samples exhibited ability to induce osteoclast differentiation. These include Dryobalanops aromatica, Euphoria longana, Lithospermum erythrorhizon, Prunus mume, Prunus nakaii, and Polygonatum odoratum. In contrast, Ailanthus altissima, Curcuma longa, Solanum nigrum, Taraxacum platycarpa, Trichosanthes kirilowii, and Daphne genkwa showed inhibitory effects in RANKL-induced osteoclast differentiation.     

Antihyperglycemic activity of compounds isolated from Indian medicinal plants

Eleven antidiabetic Indian medicinal plants were investigated in streptozotocin induced diabetic rat model and provided scientific validation to prove their antihyperglycemic activity. Antidiabetic principles from five plants were isolated. All the compounds isolated were evaluated for antihyperglycemic activity in streptozotocin induced diabetic rat model and activities were compared with standard drug metformin. Some compounds were also screened in db/db mice. Two compounds (PP-1 and PP-2) inhibited significantly the activity of PTPase-1B in an in vitro system. This might be the underlying mechanism of antihyperglycemic activity of these compounds.     

Acidic heteroxylans from medicinal plants and their anti-ulcer activity

Xylans are the main hemicelluloses found in higher plants, and are often present in phytotherapic medicines. An acidic heteroxylan was obtained from Maytenus ilicifolia leaves by hot 10% aqueous KOH extraction. This was subjected to freeze-thawing process, giving insoluble and soluble fractions and the latter treated with Fehling solution. Its insoluble fraction (MI-HX) was further examined. The acidic heteroxylan gave xylose, galactose, glucose, and 4-O-methylglucuronic acid in a 76:6:9:9 molar ratio and methylation analyses and ¹³C NMR spectroscopy showed its main chain consists of 4-O-linked β-d-Xylp units. This polysaccharide and another acidic heteroxylan from Phyllanthus niruri had anti-ulcer activity and were able to reduce gastric lesions induced by ethanol by 65% and 78%, with ED₅₀ = 40.0 and 20.4 mg/kg, each respectively. These results suggest that this class of polysaccharide has a protective anti-ulcer effect, and that there is a relation between its chemical structure and biological function.     

Cytochrome P4501A1-inhibitory action of antimutagenic anthraquinones in medicinal plants and the structure-activity relationship

We have earlier found that flavones and flavonols in vegetables specifically inhibited one of the carcinogenesis-related enzymes, cytochrome P450 (CYP) 1A1, and subsequently suppressed the mutagenicity of food-derived carcinogens. In this study, we explored other candidates for the enzyme inhibitor in Chinese medicinal plants. Some of them were antimutagenic toward 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). For example, Rheum officinale contained large amounts of anthraquinones as the active compounds, 3.4 mg of emodin, 2.1 mg of chrysophanol and 1.8 mg of rhein in 10 g of dry matter. Anthraquinones showed similar IC50 values for antimutagenicity against Trp-P-2 to those for inhibition of the N-hydroxylation activity of CYP1A1 toward Trp-P-2, indicating that the antimutagenicity was attributable to CYP inhibition. The structure-activity relationships were then examined with 14 commercial chemicals, and it was found that the interaction with an enzyme required three rings and an oxygen group in the side ring. This characteristic is similar to that of flavones and flavonols.     

Molecular basis of the antimutagenic activity of the house-cleaning inosine triphosphate pyrophosphatase RdgB from Escherichia coli

Inosine triphosphate pyrophosphatases, which are ubiquitous house-cleaning enzymes, hydrolyze noncanonical nucleoside triphosphates (inosine triphosphate (ITP) and xanthosine triphosphate (XTP)) and prevent the incorporation of hypoxanthine or xanthine into nascent DNA or RNA. Here we present the 1.5-Å-resolution crystal structure of the inosine triphosphate pyrophosphatase RdgB from Escherichia coli in a free state and in complex with a substrate (ITP + Ca^2 +) or a product (inosine monophosphate (IMP)). ITP binding to RdgB induced a large displacement of the α1 helix, closing the enzyme active site. This positions the conserved Lys13 close to the bridging oxygen between the α- and β-phosphates of the substrate, weakening the P_α-O bond. On the other side of the substrate, the conserved Asp69 is proposed to act as a base coordinating the catalytic water molecule. Our data provide insight into the molecular mechanisms of the substrate selectivity and catalysis of RdgB and other ITPases.     

Adjuvant and haemolytic activities of 47 saponins derived from medicinal and food plants

Adjuvant and haemolytic activities of 47 saponins purified from medicinal and food plants were examined. The compounds showed various levels of both adjuvant and haemolytic activities. Soyasaponins and lablabosides showed strong adjuvant activity but little haemolytic activity. Jujubosides showed strong adjuvant and haemolytic activities. Escins showed weaker adjuvant activity than the adjuvant-control, but strong haemolytic activity. Comparison of the functional groups of each saponin revealed that the acyl residue in saponin, the aldehyde group at carbon 4 in aglycone, and branched sugar chains attached to aglycone, were not essential for adjuvant activity. Furthermore, saponins with an acyl residue or oxide-ring moiety tended to show haemolytic activity. These results suggest that the adjuvant activity of saponins does not relate with haemolytic activity. It is considered that not only the functional groups themselves, but the overall conformation harmoniously consisting of such functional groups, affects adjuvant activity of saponins.     

Screening of some plants from Northern Argentina for their antimicrobial activity

AIMS: Screening of antimicrobial activity in 25 plant species from Northern Argentina. METHODS AND RESULTS: Inhibition of microbial growth was measured by a microplate assay with an oxidation-reduction indicator (Alamar Blue). Test organisms were: Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus and Enterococcus faecium. Weak inhibitory activities (MIC=0.5 mg dry matter ml(-1)) were found in methanolic extracts of Rivina humilis, Crateva tapia, Funastrum claucum and Schinopsis balansae. Stronger bacteriostatic power was detected in Vassobia breviflora (MIC=0.25 mg ml(-1) against Staphylococcus aureus, and 0.5 mg ml(-1) against Enterococcus faecium). This activity was purified five-fold by extraction with dichloromethane, and it was found equally effective against susceptible or antibiotic-resistant strains of Staph. aureus. In addition, the purified extract was synergistic with gentamicin, and it was bactericidal at 24 h, with a concentration of 0.25 mg ml(-1). CONCLUSION: There is a significant antimicrobial activity in Vassobia breviflora. SIGNIFICANCE AND IMPACT OF THE STUDY: Further studies will be required to disclose the potential importance of these findings.     

Novel antimutagenic factors derived from the edible mushroom Agrocybe cylindracea

Studies have shown that certain foods contain compounds with antigenotoxic activities. Here, we ask if dried powders and/or extracts from three edible mushrooms, Agrocybe cylindracea, Lentinula edodes and Pleurotus ostreatus, have a mitigating effect on genotoxicity. We used two in vivo assays: the Drosophila DNA repair test and the Drosophila wing spot test (also known as SMART) which measures somatic mutation and recombination. Eight carcinogens were tested with the mushroom powders: 2-AAF, aflatoxin B1, DMBA, IQ, MeIQx, MNU NDMA, and 4NQO. We found that A. cylindracea and P. ostreatus powders can suppress DNA damage induced by each of the mutagens we tested. In contrast, L. edodes has an inhibitory effect on DNA damage induced by only a sub-set of mutagens, namely aflatoxin B1, NDMA, MNU and 4NQO. In addition, A. cylindracea extracts were able to suppress somatic cell mutation induced by aflatoxin B1, MMC, MNU, NDMA, NMOR and 4NQO. These results suggest that Agrocybe genus mushrooms contain factors with antigenotoxic activity, including anti-recombinogenic activity. Furthermore, the antigenotoxic activity of A. cylindracea powder can be extracted in water but not in ethyl acetate or methanol, and is sensitive to heat treatment. The data suggest that there is a novel antigenotoxic factor(s) in A. cylindracea, possibly in the form of a peptide or protein.     

Screening for hydroxynitrile lyase activity in non-commercialised plants

Hydroxynitrile lyases are used for the synthesis of enantiomerically pure cyanohydrins which are of great importance in the pharmaceutical and fine chemical industries. In this study, the hydroxynitrile lyase activity of 100 plants from 40 families was investigated, first by screening for cyanogenic activity, followed by a hydroxynitrile lyase activity assay. Of the 100 plants, four were found to be cyanogenic and exhibited specific hydroxynitrile lyase activity: Adenia sp. (0.44 U/mg), Adenia firingalavensis (2.88 U/mg), Adenia fruticosa (1.99 U/mg) and, Adenia pechuelii (2.35 U/mg), all from the family Passifloraceae. This is the first report of hydroxynitrile lyase activity in these plants.     

Comparative studies of the phytochrome system in cell cultures from different plants

Phytochrome contents have been assayed in vivo in cell suspension cultures of Petroselinum hortense, Daucus carota and Glycine max. After transferring the cells to fresh medium phytochrome increased in parallel with the increase in cell number, whereas the amount of phytochrome per cell remained constant. The rate of phytochrome reaccumulation after pretreatment with 15 h red light was very similar in all three systems (2.8–3.6 (e) 10^–5/h). Dark reversion and a fast and slow P_fr destruction were observed in all systems. The rate constants of these reactions varied strongly between the systems. The phytochrome systems of the cell cultures were compared with those of etiolated and light-grown seedlings and it was concluded that the cell suspension cultures of Petroselinum hortense and Daucus carota behaved similarly to light-grown seedlings. In contrast, those of Glycine max behaved similarly to a dark grown seedling.Abbreviations P_r'fr red, far-red absorbing forms of phytochrome - P_tot P_r+P_fr total amount of phytochrome - fwt fresh weight     

Selection for high seed oil content in soybean families derived from plants regenerated from protoplasts and tissue cultures

Recurrent selection for high seed oil content was carried out with 2,008 progeny of 28 plants regenerated via embryogenesis, 95 via organogenesis and 25 from protoplasts via organogenesis from five different soybean cultivars. Two lines derived from plants regenerated from the cultivar Jack with small increases in seed oil content emerged after three selection cycles in the field but in both cases the protein content was decreased and the seed yield of one of the lines was also decreased. Apparently somaclonal variation for seed oil content can arise, but on the basis of the decreases in protein and yield found in this study, this small change is not useful for soybean improvement. Received: 22 July 2000 / Accepted: 28 July 2000     

Structure-radical scavenging activity relationships of phenolic compounds from traditional Chinese medicinal plants

Traditional Chinese medicinal plants associated with anticancer contain a wide variety of natural phenolic compounds with various structural features and possessing widely differing antioxidant activity. The structure-radical scavenging activity relationships of a large number of representative phenolic compounds (e.g., flavanols, flavonols, chalcones, flavones, flavanones, isoflavones, tannins, stilbenes, curcuminoids, phenolic acids, coumarins, lignans, and quinones) identified in the traditional Chinese medicinal plants were evaluated using the improved ABTS*+ and DPPH methods. Different categories of tested phenolics showed significant mean differences in radical scavenging activity. Tannins demonstrated the strongest activity, while most quinones, isoflavones, and lignans tested showed the weakest activity. This study confirmed that the number and position of hydroxyl groups and the related glycosylation and other substitutions largely determined radical scavenging activity of the tested phenolic compounds. The differences in radical scavenging activity were attributed to structural differences in hydroxylation, glycosylation and methoxylation. The ortho-dihydroxy groups were the most important structural feature of high activity for all tested phenolic compounds. Other structural features played a modified role in enhancing or reducing the activity. Within each class of phenolic compounds, the structure-activity relationship was elucidated and discussed. This study reveals the structure-activity relationships of a large series of representative natural phenolic compounds more systematically and fully than previous work. Structure-radical scavenging activity relationships of some natural phenolics identified in the medicinal plants were evaluated for the first time.