Antibacterial activity of medicinal plant extracts against periodontopathic bacteria

This study was performed to evaluate the antibacterial activity of Althaea officinalis L. roots, Arnica montana L. flowers, Calendula officinalis L. flowers, Hamamelis virginiana L. leaves, Illicium verum Hook. fruits and Melissa officinalis L. leaves, against anaerobic and facultative aerobic periodontal bacteria: Porphyromonas gingivalis, Prevotella spp., Fusobacterium nucleatum, Capnocytophaga gingivalis, Veilonella parvula, Eikenella corrodens, Peptostreptococcus micros and Actinomyces odontolyticus. The methanol extracts of H. virginiana and A. montana and, to a lesser extent, A. officinalis were shown to possess an inhibiting activity (MIC < or = 2048 mg/L) against many of the species tested. In comparison, M. officinalis and C. officinalis extracts had a lower inhibiting activity (MIC > or = 2048 mg/L) against all the tested species with the exception of Prevotella sp. Illicium verum methanol extract was not very active though it had a particular good activity against E. corrodens. The results suggest the use of the alcohol extracts of H. virginiana, A. montana and A. officinalis for topical medications in periodontal prophylactics.     

Antimicrobial effects of Thai medicinal plants against acne-inducing bacteria

Propionibacterium acnes and Staphylococcus epidermidis have been recognized as pus-forming bacteria triggering an inflammation in acne. The present study was conducted to evaluate antimicrobial activities of Thai medicinal plants against these etiologic agents of acne vulgaris. Crude extracts were tested for antimicrobial activities by disc diffusion and broth dilution methods. The results from the disc diffusion method showed that 13 medicinal plants could inhibit the growth of Propionibacterium acnes. Among those, Senna alata, Eupatorium odoratum, Garcinia mangostana, and Barleria lupulina had strong inhibitory effects. Based on a broth dilution method, the Garcinia mangostana extract had the greatest antimicrobial effect. The MIC values were the same (0.039 mg/ml) for both bacterial species and the MBC values were 0.039 and 0.156 mg/ml against Propionibacterium acnes and Staphylococcus epidermidis, respectively. In bioautography assay, the Garcinia mangostana extract produced strong inhibition zones against Propionibacterium acnes. Antimicrobial activity from fractions of column chromatography revealed one of the active compounds in Garcinia mangostana could be mangostin, a xanthone derivative. Taken together, our data indicated that Garcinia mangostana had a strong inhibitory effect on Propionibacterium acnes and Staphylococcus epidermidis. Therefore, this plant would be an interesting topic for further study and possibly for an alternative treatment for acne.     

Antibacterial activity of traditional Australian medicinal plants

Fifty-six ethanolic extracts of various parts of 39 plants used in traditional Australian Aboriginal medicine were investigated for their antibacterial activities against four Gram-positive (Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus and Streptococcus pyogenes) and four Gram-negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella typhimurium) bacterial species. In a plate-hole diffusion assay, 12 extracts inhibited the growth of one or more of the bacteria, with five extracts showing broad spectrum antibacterial activity against Gram-positive bacteria. B. cereus was the most susceptible bacterium, with all 12 extracts displaying activity against this organism. Extracts from the leaves of Eremophila species (Myoporaceae) were the most active, with Eremophila duttonii exhibiting the greatest activity (against Gram-positive bacteria). The antibacterial effects of E. duttonii were further investigated by time-course growth assays which showed that significant growth inhibition was observed in cultures incubated in the presence of the extract within 1 h for B. cereus, E. faecalis and S. aureus and 2 h for S. pyogenes.     

Antibacterial activity of some Moroccan medicinal plants

The extracts of 12 plants selected on the basis of the folk-medicine reports were examined for their antibacterial effects against eight pathogenic bacteria. The n-butanol extract of Calotropis procera flowers and the aqueous extract of Eugenia caryophyllata proved to be the most effective against the bacteria tested.     

Antibacterial activity of East African medicinal plants

In an ethnopharmacological survey, extracts of the six East African medicinal plants Entada abyssinica (stem bark), Terminalia spinosa (young branches), Harrisonia abyssinica (roots), Ximenia caffra (roots), Azadirachta indica (stem bark and leaves), and Spilanthes mauritiana (roots and flowers) were tested against 105 strains of bacteria from seven genera (Staphylococcus, Enterococcus, Pseudomonas, Escherichia, Klebsiella, Salmonella, Mycobacterium). The minimum inhibitory concentration reached by 50% (MIC_50%) and 90% (MIC_90%) of the strains for the extracts of E. abyssinica, T. spinosa, X. caffra, and A. indica (stem bark) ranged from 0.13–8 mg/ml and from 0.5 to >8 mg/ml, respectively. Their minimum bactericidal concentration by 50% (MBC_50%) and MBC_90% were all between 0.5 and >8 mg/ml. H. abyssinica, A. indica (leaves), and S. mauritiana (roots and flowers) had MIC and MBC values ≥8 mg/ml. Mycobacteria were not inhibited at extract concentrations of 0.5–2 mg/ml. lt is concluded that plant extracts with low MIC and MBC values may serve as sources for compounds with therapeutic potency.     

Antibacterial and antifungal activity of traditional medicinal plants used against venereal diseases in South Africa

Aqueous, ethanolic and ethyl acetate extracts of 13 plants used in South Africa for the treatment of venereal diseases were screened for antibacterial and antifungal activity. Among the plants tested, Gunnera perpensa, Harpephyllum caffrum, Hypoxis latifolia and Ledebouria ovatifolia showed the best antibacterial activity. The aqueous extracts of Gunnera perpensa and Harpephyllum caffrum were most active against all the tested bacteria. In antifungal screening, good activity was shown by the ethanolic extracts of Bersama lucens and Harpephyllum caffrum. Only in the case of Harpephyllum caffrum did aqueous extracts have activity against Candida albicans.     

Antioxidant activities of extracts from five anti-viral medicinal plants

The antioxidant activities of five medicinal plants (Ampelopsis sinica, Ampelopsis humiliforlia var. heterophylla, Potentilla freyniana, Selaginella labordei and Chrysanthemum multiflorum), used in the Hubei province of China, have been investigated using both enzymatic and non-enzymatic in vitro antioxidant assays. Extracts from all five of the plants inhibited xanthine oxidase and lipoxygenase activities, and were scavengers of the ABTS*+ radical cation using the Trolox equivalent antioxidant capacity assay (TEAC). Extracts from Potentilla freyniana and Selaginella labordei down-regulated cyclooxygenase-2 gene expression, measured by real-time RT-PCR, in human colon adenocarcinoma CaCo-2 cells.     

Antibacterial activity of South African plants used for medicinal purposes

Crude extracts from 21 South African medicinal plants, traditionally used for ailments of an infectious or septic nature, were screened for in vitro antibacterial activity using the agar diffusion and dilution methods. Almost all the activity exhibited was against Gram-positive bacteria, with 12 of the 21 plant species tested showing some activity against Bacillus subtilis. Only the Warburgia salutaris methanol extract inhibited the growth of Escherichia coli. None of the extracts had any activity against Klebsiella pneumoniae. The highest activity was found in the methanol extracts from Bidens pilosa, Psidium guajava, Artemisia afra and Warburgia salutaris. The majority of the antibacterial activity was present in the methanolic, rather than the aqueous extracts.     

Cytotoxicity and modes of action of five Cameroonian medicinal plants against multi-factorial drug resistance of tumor cells

Ethnopharmacological relevance

Beilschmiedia acuta Kosterm, Clausena anisata (Willd) Hook, Fagara tessmannii Engl., Newbouldia laevis Seem., and Polyscias fulva (Hiern) Harms. are medicinal plants used in Cameroonian traditional medicine in the treatment of various types of cancers. The present study aims at investigating 11 methanolic extracts from the above Cameroonian medicinal plants on a panel of human cancer cell lines, including various drug-resistant phenotypes. Possible modes of action were analyzed for two extracts from Beilschmiedia acuta and Polyscia fulva and alpha-hederin, the representative constituent of Polyscia fulva.

Materials and methods

Cytotoxicity was determined using a resazurin assay. Cell cycle, apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) were measured by flow cytometry. Cellular response to alpha-hederin was investigated by a mRNA microarray approach.

Results

Prescreening of extracts (40 µg/mL) showed that three of eleven plant extracts inhibited proliferation of CCRF-CEM cells by more than 50%, i.e. BAL (73.65%), the bark extract of Beilschmiedia acuta (78.67%) and PFR (68.72%). Subsequent investigations revealed IC₅₀ values below or around 30 µg/mL of BAL and PFR in 10 cell lines, including drug-resistant models, i.e. P-glycoprotein-overexpressing CEM/ADR5000, breast cancer resistance protein-transfected MDA-MB-231-BCRP, TP53 knockout cells (HCT116 p53^−/−), and mutation-activated epidermal growth factor receptor-transfected U87MG.ΔEGFR cells. IC₅₀ values below 5 µg/mL of BAL were obtained for HCT116 (p53^−/−) cells. IC₅₀ values below 10 µM of alpha-hederin were found for sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 cells. The BAL and PFR extracts induced cell cycle arrest between G0/G1 and S phases. PFR-induced apoptosis was associated with increased ROS generation and MMP breakdown. Microarray-based cluster analysis revealed a gene expression profile that predicted cellular response to alpha-hederin.

Conclusion

BAL, PFL and alpha-hederin, an exemplarily taken constituent of Beilschmiedia acuta and Polyscia fulva extracts revealed cytotoxicity towards cancer cell lines. Hence, Beilschmiedia acuta and Polyscia fulva may be valuable to develop drugs against otherwise drug-resistant cancer cells.     

Antimicrobial activity of medicinal plants against oral microorganisms

Ethanol extracts of eight plant species used traditionally in South Africa for the treatment of oral diseases were investigated for in vitro antimicrobial activity against oral pathogens namely Actinobacillus actinomycetemcomitans, Actinomyces naeslundii, Actinomyces israelii, Candida albicans, Porphyromonus gingivalis, Privotella intermedia and Streptococcus mutans using the disk diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ethanol extracts were determined against these microorganisms using micro dilution. The cytotoxicity and therapeutic index (TI) of selected active extracts were also determined. Out of eight plants, six (Annona senegalensis, Englerophytum magalismontanum, Dicerocarym senecioides, Euclea divinorum, Euclea natalensis, Solanum panduriforme and Parinari curatellifolia) exhibited MIC values ranging from 25.0 mg/ml to 0.8 mg/ml. Gram negative bacteria were found to be more resistant to the plant extracts than Gram positive bacteria, except for Euclea natalensis which inhibited all three Gram negative bacteria tested in this study. All plant extracts showed moderate cytotoxicity on the Vero cell line. The fifty percent inhibitory concentration (IC₅₀) of all plants tested range from 92.3 to 285.1 μg/ml.     

Evaluation of five medicinal plants used in diarrhoea treatment in Nigeria

Five medicinal plants [Acacia nilotica, Acanthospermun hispidum, Gmelina arborea, Parkia biglobosa and Vitex doniana] used in diarrhoeal treatment in Kaduna State, Nigeria, were investigated. This study was carried out on perfused isolated rabbit jejunum and castor oil-induced diarrhoea in mice. The aqueous methanol extracts (0.5, 1.0, 2.0 and 3.0 mg/ml) were generally found to cause a dose-dependent response in the isolated rabbit jejunum, though this was not uniform in all the plants. Gmelina arborea and Vitex doniana showed concentration dependent relaxation at low doses (0.5, 1.0 mg/ml), but showed no significant relaxation at higher doses (2.0, 3.0 mg/ml). Other extracts showed biphasic effects. For example, Acacia nilotica at 3.0 mg/ml caused initial relaxation quickly followed by contraction. In the castor oil-induced diarrhoeal, 100% protections were shown by extracts of Acacia nilotica and Parkia biglobosa (100, 200 mg/kg) while Vitex doniana showed a dose-dependent effect. The least protection was shown by Acanthospermun hispidum, at the same dose, when compared with the other four plants. The results obtained revealed that the aqueous methanol extracts of all the five medicinal plants investigated have pharmacological activity against diarrhoea. This may explain their use in traditional medicine for the treatment of diarrhoea.     

Brine shrimp toxicity and antiplasmodial activity of five Kenyan medicinal plants

The organic extracts of leaves and roots of five plants used for treating malaria in Central, Nairobi and Rift Valley Provinces, Kenya were tested for brine shrimp lethality and in vitro antiplasmodial activity against chloroquine sensitive and resistant strains of Plasmodium falciparum. Of the plants tested, 60% were toxic to the brine shrimp (LC(50)<30 microg/ml) and eight out of ten plant parts (80%) showed in vitro antiplasmodial activity (IC(50)<50 microg/ml). Among the extracts screened, the leaves of Cyathula polcephala had the highest toxicity to the brine shrimp (LC(50)=2.9 microg/ml) while the leaves of Pentas longiflora had the best antiplasmodial activity (IC(50)=11. /ml). The plant extracts with low IC(50) values are potential sources for novel antiplasmodial compounds.     

Antibacterial activities of extracts from Ugandan medicinal plants used for oral care

Ethnopharmacological relevance

Medicinal plants are widely used for treatment of oral/dental diseases in Uganda.

Aim of the study

To investigate antibacterial activities of 16 commonly used medicinal plants on microorganisms associated with periodontal diseases (PD) and dental caries (DC).

Materials and methods

Pulp juice and solvent extracts (hexane, methanol and water) from the plants were tested against Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia associated with PD and Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus associated with DC. Tests were done using agar well-diffusion (pulp juice) and agar-dilution (Solvent extracts) assays.

Results

Pulp juice from Zanthoxylum chalybeum and Euclea latidens showed activity against all the bacteria, Zanthoxylum chalybeum being most active. Hexane extract from aerial part of Helichrysum odoratissimum was most active (MIC: 0.125–0.5 mg/ml). Methanol extract from leaves of Lantana trifolia showed activity against all bacteria (MIC: 0.25–1 mg/ml).

Conclusion

Several of the tested plants showed antibacterial activities against bacteria associated with PD and DC, meriting further investigations.     

In vitro anthelmintic activity of crude extracts of five medicinal plants against egg-hatching and larval development of Haemonchus contortus

Ethnopharmacological relevance

Senna occidentalis, Leonotis ocymifolia, Leucas martinicensis, Rumex abyssinicus, and Albizia schimperiana are traditionally used for treatment of various ailments including helminth infection in Ethiopia.

Materials and Methods

In vitro egg hatch assay and larval development tests were conducted to determine the possible anthelmintic effects of crude aqueous and hydro-alcoholic extracts of the leaves of Senna occidentalis, aerial parts of Leonotis ocymifolia, Leucas martinicensis, Rumex abyssinicus, and stem bark of Albizia schimperiana on eggs and larvae of Haemonchus contortus.

Results

Both aqueous and hydro-alcoholic extracts of Leucas martinicensis, Leonotis ocymifolia and aqueous extract of Senna occidentalis and Albizia schimperiana induced complete inhibition of egg hatching at concentration less than or equal to 1 mg/ml. Aqueous and hydro-alcoholic extracts of all tested medicinal plants have shown statistically significant and dose dependent egg hatching inhibition. Based on ED₅₀, the most potent extracts were aqueous and hydro-alcoholic extracts of Leucas martinicensis (0.09 mg/ml), aqueous extracts of Rumex abyssinicus (0.11 mg/ml) and Albizia schimperiana (0.11 mg/ml). Most of the tested plant extracts have shown remarkable larval development inhibition. Aqueous extracts of Leonotis ocymifolia, Leucas martinicensis, Albizia schimperiana and Senna occidentalis induced 100, 99.85, 99.31, and 96.36% inhibition of larval development, respectively; while hydro-alcoholic extracts of Albizia schimperiana induced 99.09 inhibition at the highest concentration tested (50 mg/ml). Poor inhibition was recorded for hydro-alcoholic extracts of Senna occidentalis (9%) and Leonotis ocymifolia (37%) at 50 mg/ml.

Conclusions

The overall findings of the current study indicated that the evaluated medicinal plants have potential anthelmintic effect and further in vitro and in vivo evaluation is indispensable to make use of these plants.     

Antibacterial and wound healing properties of methanolic extracts of some Nigerian medicinal plants

This study was conducted to evaluate methanolic extracts of Ageratum conyzoides, Anthocleista djalonensis, Napoleona imperialis, Ocimum gratissimum, and Psidium guajava for antibacterial and wound healing properties. Antibacterial properties of the extracts were studied against eleven wound isolates (Staphylococcus aureus (four strains), E. coli (two strains), Pseudomonas aeruginosa (one strain), Proteus spp. (three strains), and Shigella spp. (one strain)) using the well diffusion method. Wound healing properties of Ageratum conyzoides, Anthocleista djalonensis, Napoleonaea imperialis, and Ocimum gratissimum were determined using the excision wound model. Extract of Napoleona imperialis inhibited growth of all the test bacterial strains while Psidium guajava and Anthocleista djalonensis extracts prevented growth of 81.8 and 72.7% of the test organisms, respectively. Ageratum conyzoides and Ocimum gratissimum extracts did not inhibit growth of any of the test organisms. More than 90% wound healing was recorded in the extract and cicatrin powder treated groups by 14 days post surgery, where as 72% healing was observed in the distilled water-treated group. The percentage healing in the distilled water-treated group was significantly different (P<0.001) from those of extract and antibiotic-treated groups.     

Antibacterial and anti-inflammatory activities of some plants used for medicinal purposes in Kenya

Aqueous, hexane and methanol extracts of 12 plant species, traditionally used in Kenya for treatment of ailments of infectious and/or inflammatory nature were screened for in vitro antibacterial and anti-inflammatory activities. Antibacterial activity was tested using the agar diffusion method while anti-inflammatory activity was tested using the cyclooxygenase (COX-1) assay. All the antibacterial activity was against Gram-positive bacteria with nine plant species showing some activity against Staphylococcus aureus. The highest activity was found in the methanol extracts of Maytenus senegalensis, Plectranthus barbatus, Zanthoxylum chalybeum, Zanthoxylum usambarense and hexane extracts of Spiranthes mauritianum. All the plant species showed some anti-inflammatory activities. In most cases, methanol extracts caused higher inhibition than aqueous and hexane extracts.     

Antibacterial activity of some Peruvian medicinal plants from the Callejon de Huaylas.

Extracts of eight medicinal plants from the Callejon de Huaylas in Peru were screened for antibacterial activity in eighteen bacterial strains by the agar-diffusion method; six of these were active against a variety of bacteria.     

Screening of Brazilian medicinal plants for antiviral activity against rotavirus

Ethnopharmacological relevance

Brazilian medicinal plants traditionally used for the treatment of diarrhoea were investigated for their in vitro antiviral activity against the simian rotavirus SA11.

Materials and methods

The ethanolic crude extracts of plants collected in the cerrado of Minas Gerais, Brazil were submitted to phytochemical screening. The cytotoxicity of the extracts was inferred by cellular morphologic alterations. Antiviral activity was assessed by the ability of the extracts to inhibit the cytopathic effect (CPE) of rotavirus on the treated cells. RT-PCR was performed to confirm and/or confront antiviral assay data.

Results

The maximum non-toxic concentration ranged from 50 to 500 μg/mL. All extracts were toxic at a concentration of 5000 μg/mL but no extract showed cytotoxicity at 50 μg/mL. The species Byrsonima verbascifolia, Myracrodruon urundeuva, Eugenia dysenterica and Hymenaea courbaril exhibited the strongest in vitro activity against rotavirus. Their extracts prevented the formation of CPE, and RT-PCR analysis detected no amplification of genetic material from rotavirus. Tannins, flavonoids, saponins, coumarins and terpenes were the major classes of natural products found in the leaf extracts that showed antiviral activity.

Conclusion

Among the species studied, Byrsonima verbascifolia, Eugenia dysenterica, Hymenaea courbaril and Myracrodruon urundeuva showed potential activity against rotavirus and are worthy of further study. The present study corroborates ethnopharmacological data as a valuable source in the selection of plants with antiviral activity and to some extent validates their traditional uses.     

Antibacterial potential of Antarctic lichens against human pathogenic Gram-positive bacteria

Extracts from five Antarctic lichens (L3, Stereocaulon alpinum; L5, Ramalina terebrata; L6, Caloplaca sp.; L8, Lecanora sp.; and L17, Caloplaca regalis) were tested for antimicrobial activities against several clinically important microbes by disk diffusion. The minimum inhibitory concentration (MIC) of each extract was determined by a broth dilution method. Extracts from L3, L5, L6 and L8 were active against two Gram(+) strains. B. subtilis was more sensitive to lichen extracts (except L5) than S. aureus. The MIC of lichen extracts against B. subtilis and S. aureus was observed from 36.7 +/- 0.3 to 953.8 +/- 85.8 microg/mL and 68.5 +/- 0.6 to >1000 microg/mL, respectively. Comparisons of MIC values of Antarctic lichen crude extracts to previously published MIC values of some reported lichen metabolites against Gram(+) bacteria indicated that Antarctic lichens might be an enriched source of effective antibacterial agents against clinically relevant Gram(+) species.     

Antibacterial activity of crude extracts from Mexican medicinal plants and purified coumarins and xanthones

Thirty-two extracts from 22 Mexican medicinal plants of 15 different families were assayed to determine their antibacterial activity against Escherichia coli and Staphylococcus aureus. Seventeen plants showed antibacterial activity, while five plants showed no activity against both bacteria. All of the extracts showed higher activity against Staphylococcus aureus (methicillin-sensitive and methicillin-resistant) than against Escherichia coli, except one. Among the plants examined, Bursera simaruba (L.) Sarg. (Burseraceae), Haematoxylum brasiletto H. Karst. (Fabaceae), Calophyllum brasiliense Cambess. (Clusiaceae), and Mammea americana L. (Clusiaceae) were highly active against Staphylococcus aureus. Coumarins (mammea A/BA and mammea A/AA) and xanthones, namely jacareubin and 1,3,5,6-tetrahydroxy-2-(3,3-dimethylallyl) xanthone, were isolated as the principle compounds from the last two plants.