In vitro evaluation of Datura innoxia (thorn-apple) for potential antibacterial activity

Various parts of Datura innoxia were examined for potential antibacterial activity by preparing their crude aqueous and organic extracts against Gram-negative bacteria (Escherichia coli and Salmonella typhi) and Gram-positive bacteria (Bacillus cereus, Bacillus subtilis and Staphylococcus aureus). The results of agar well diffusion assay indicated that the pattern of inhibition depends largely upon the plant part, solvent used for extraction and the organism tested. Extracts prepared from leaves were shown to have better efficacy than stem and root extracts. Organic extracts provided potent antibacterial activity as compared to aqueous extracts. Among all the extracts, methanolic extract was found most active against almost all the bacterial species tested. Gram-positive bacteria were found most sensitive as compared to Gram-negative bacteria. Staphylococcus aureus was signifi cantly inhibited by almost all the extracts even at very low MIC followed by other Gram-positives. For Escherichia coli (a Gram-negative bacterium), the end point was not reached for ethyl acetate extract while it was very high for other extracts. The study promises an interesting future for designing a potentially active antibacterial agent from Datura innoxia.     

Comparative activity against pathogenic bacteria of the root,stem, and leaf of <Emphasis Type="Italic">Raphanus sativus</Emphasis> grown in India

Aqueous, methanol, ethyl acetate, and chloroform extracts of the root, stem, and leaf of Raphanus sativus were studied for antibacterial activity against food-borne and resistant pathogens. All extracts except the aqueous extracts had significant broad-spectrum inhibitory activity. The ethyl acetate extract of the root had the potent antibacterial activity, with a minimum inhibitory concentration (MIC) of 0.016–0.064 mg/ml and a minimum bactericidal concentration (MBC) of 0.016–0.512 mg/ml against health-damaging bacteria. This was followed by the ethyl acetate extracts of the leaf and stem with MICs of 0.064–0.256 and 0.128–0.256 mg/ml, respectively and MBCs of 0.128–2.05 and 0.256–2.05 mg/ml, respectively. The ethyl acetate extracts of the different parts of R. sativus retained their antibacterial activity after heat treatment at 100°C for 30 min, and their antibacterial activity was enhanced when pH was maintained in the acidic range. Hence this study, for the first time, demonstrated that the root, stem, and leaf of R. sativus had significant bactericidal effects against human pathogenic bacteria, justifying their traditional use as anti-infective agents in herbal medicines.     

Antibacterial activity of ethanolic and aqueous extracts of Acacia aroma Gill. ex Hook et Arn

The purpose of the present study was to investigate the antibacterial activity of seven ethanolic extracts and three aqueous extracts from various parts (leaves, stems and flowers) of A. aroma against 163 strains of antibiotic multi-resistant bacteria. The disc diffusion assay was performed to evaluate antibacterial activity of the A. aroma crude extracts, against several Gram-positive bacteria (E. faecalis, S. aureus, coagulase-negative stahylococci, S. pyogenes, S. agalactiae, S. aureus ATCC 29213, E. faecalis ATCC 29212) and Gram-negative bacteria (E. coli., K. pneumoniae, P. mirabilis, E. cloacae, S. marcescens, M morganii, A. baumannii, P. aeruginosa, S. maltophilia, E. coli ATCC 35218, P. aeruginosa ATCC 27853, E. coli ATCC 25922). All ethanolic extracts showed activity against gram-positive bacteria. Among all obtained extracts, only leaf and flower fluid extracts showed activity against Gram-negative bacteria. Based on this bioassay, leaf fluid extracts tended to be the most potent, followed by flower fluid extracts. Minimal inhibitory concentration (MIC) values of extracts and antibiotics were comparatively determined by agar and broth dilution methods. Both extracts were active against S. aureus, coagulase-negative stahylococci, E. faecalis and E. faecium and all tested Gram-negative bacteria with MIC values from 0.067 to 0.308 mg/ml. In this study the minimal bactericidal concentration (MBC) values were identical or twice as high than the corresponding MIC for leaf extracts and four or eight times higher than MIC values for flower extracts. This may indicate a bactericidal effect. Stored extracts have similar antibacterial activity as recently obtained extracts. The A. aroma extracts of leaves and flowers may be useful as antibacterial agents against Gram- negative and Gram-positive antibiotic multi-resistant microorganisms.     

Evaluation of antimicrobial activity of the lichens <Emphasis Type="Italic">Lasallia pustulata,Parmelia sulcata,Umbilicaria crustulosa</Emphasis>, and <Emphasis Type="Italic">Umbilicaria cylindrica</Emphasis>

The antimicrobial properties of acetone, methanol, and aqueous extracts of the lichens Lasallia pustulata, Parmelia sulcata, Umbilicaria crustulosa, and Umbilicaria cylindrica were studied comparatively in vitro. Antimicrobial activities of the extracts of different lichens were estimated by the disk diffusion test for Gram-positive bacteria, Gram-negative bacteria, and fungal organisms, as well as by determining the MIC (minimal inhibitory concentration). The obtained results showed that the acetone and methanol extracts of Lasallia pustulata, Parmelia sulcata, and Umbilicaria crustulosa manifest antibacterial activity against the majority of species of bacteria tested, in addition to selective antifungal activity. The MIC of lichen extracts was lowest (0.78 mg/ml) for the acetone extract of Lasallia pustulata against Bacillus mycoides. Aqueous extracts of all of the tested lichens were inactive. Extracts of the lichen Umbilicaria cylindrica manifested the weakest activity, inhibiting only three of the tested organisms.     

Anticandidial and anticryptococcal activity of <Emphasis Type="Italic">Euphorbia fusiformis</Emphasis>, a rare medicinal plant

The present work demonstrates the screening of extracts of the rare medicinal herb Euphorbia fusiformis for antifungal activity. The main aim was to investigate its antifungal properties against Candida albicans and Cryptococcus neoformans, the causative agents of human candidiasis and cryptococcosis, respectively. Aqueous and organic solvent extracts from the leaves and rootstock of the plant were tested against the fungi by the well-in-agar method. Almost all the organic solvent extracts exhibited an inhibitory effect against C. albicans and to some extent on C. neoformans, except for the aqueous extracts, which had no effect. The combined formulations of the extracts also had better activity against C. albicans than C. neoformans. This study thus concludes by demonstrating the antifungal properties of E. fusiformis and also the potential research in identifying the active principles, which may have future therapeutic value.     

Antibacterial activity of some salt marsh halophytes and mangrove plants against methicillin resistant Staphylococcus aureus

The antibacterial activity of aqueous and methanol extracts of leaves/shoots of five salt marsh halophytes and six mangroves was studied against methicillin resistant, clinical isolates of Staphylococcus aureus. There was a clear comparability between the salt marsh halophytes and mangroves in their antibacterial action. The mangrove plants possessed higher antibacterial potency than the salt marsh halophytes. The highest activity was recorded with the methanol extract of Excoecaria agallocha followed by the methanol extracts of Aegiceras corniculatum, Lumnitzera racemosa and Ceriops decandra. The minimum inhibitory concentration (MIC) values ranged from 0.125 to 4 mg/mL and 1 to 16 mg/mL for methanol and aqueous extracts, respectively. Further separation of active principle from the potent mangrove plant will be useful for the control of drug resistant strains of S. aureus.     

Studies on the efficiency of different extraction procedures on the anti microbial activity of selected medicinal plants

Many doubts still persist even today when it comes to selection of the solvents for extracting the active constituents from various Indian medicinal plants. This study was aimed at assessing and establishing the best solvent for extracting the active constituents from 10 plant extracts. Thin layer chromatography (TLC) was used to separate and establish the active constituents present in each of the medicinal plants. Active constituents from each plant were extracted by using three different solvent systems namely diethyl ether, chloroform and hexane and were tested against three species of gram negative and three species of gram positive bacteria (Escherichia coli, Pseudomonas aureginosa, Streptococcus pneumoniae, Aeromonas hydrophila, Staphylococcus aereus, Bacillus cereus) by means of agar well diffusion assay. Studies on the antioxidant activity studies were also carried out for these plant extracts by using Diphenylpicryl-hydrazyl (DPPH) method. For the antimicrobial activity, the study revealed that among the selected plants, Azadiracta indica, Pongamia pinnata, Aloe barbadensis had the maximum antibacterial activity. Among the extraction procedures diethyl ether was found to be the best solvent that could be used for the extraction procedure. On the antioxidant activity part, Coleus amboinicus and Calotropis procera were found to have high antioxidant activity of 91.64% and 88.72% respectively and the further results are reported and discussed.     

Plant growth inhibitory activity of Ophiopogon japonicus Ker-Gawler and role of phenolic acids and their analogues: a comparative study

Allelopathic potential of Ophiopogon japonicus was investigated. The methanolic extract of O. japonicus roots strongly inhibited root and hypocotyls growth of lettuce. Sequential partitioning of the methanol extract with organic solvents showed that the diethyl ether and n-butanol extract possess strong plant growth inhibitory activities. The allelopathic constituents of the diethyl ether extract were isolated and identified as salicylic acid and p-hydroxybenzoic acid by NMR spectroscopy. Both of these phenolic acids were found in the aqueous extracts of leaves as well. The concentration of salicylic acid in roots and leaves were estimated as 0.011 and 0.02%, respectively, and it inhibited the root and shoot of tested plants by 50% even at less than 3 ppm. The p-hydroxybenzoic acid on the other hand was in less abundance (0.005%) and inhibited the plant growth to a lesser extent. The biological activity of commercially available O-methyl derivatives of these phenolic acids was also determined to establish structure–activity relationship. Among these, salicylic acid was found to be the most active one. These results suggest that Ophiopogon japonicus produces plant growth inhibitors, which are responsible for its potential allelopathic activity.     

Chemical composition and antibacterial activity of Cordia verbenacea extracts obtained by different methods

The present study describes the chemical composition and the antibacterial activity of extracts from Cordia verbenacea DC (Borraginaceae), a traditional medicinal plant that grows widely along the southeastern coast of Brazil. The extracts were obtained using different extraction techniques: high-pressure operations and low-pressure methods. The high-pressure technique was applied to obtain C. verbenacea extracts using pure CO₂ and CO₂ with co-solvent at pressures up to 30 MPa and temperatures of 30, 40 and 50 °C. Organic solvents such as n-hexane, ethyl acetate, ethanol, acetone and dichloromethane were used to obtain extracts by low-pressure processes. The antibacterial activity of the extracts was also subjected to screening against four strains of bacteria using the agar dilution method. The extraction yields were up to 5.0% w/w and up to 8.6% w/w for supercritical fluid extraction with pure CO₂ and with ethyl acetate as co-solvent, respectively, while the low-pressure extraction indicates yields up to 24.0% w/w in the soxhlet extraction using water and aqueous mixture with 50% ethanol as solvents. The inhibitory activity of the extracts in Gram-positive bacteria was significantly higher than in Gram-negative. The quantification and the identification of the extracts recovered were accomplished using GC/MS analysis. The most important components identified in the extract were artemetin, β-sitosterol, α-humulene and β-caryophyllene, among others.     

Evaluation of antioxidant and antibacterial activity of methanolic extracts of Gentiana kurroo royle

In this study our objective was to evaluate the antioxidant and antimicrobial activity of methanolic extracts of leaves and roots of Gentiana kurroo. The antioxidant activities of the extracts were examined using different biochemical assays namely diphenylpicrylhydrazyl (DPPH), nitroblue tetrazolium (NBT) and ferric reducing power (FRAP). In all the assays, root extract exhibited stronger antioxidant activity than that of leaves. The antibacterial activity of the extracts was also evaluated and MIC values were calculated by broth dilution method. Although, the extracts prevented the growth of both Gram positive and Gram negative bacteria, the MIC values of methanolic extract of the leaves were higher than those of the root extract. The antibacterial and antioxidant activity of the extracts was found to be positively associated with the total phenolic and flavonoid content of the extracts.     

Isolation and structural characterisation of two antibacterial free fatty acids from the marine diatom, <Emphasis Type="Italic">Phaeodactylum tricornutum</Emphasis>

One solution to the global crisis of antibiotic resistance is the discovery of novel antimicrobial compounds for clinical application. Marine organisms are an attractive and, as yet, relatively untapped resource of new natural products. Cell extracts from the marine diatom, Phaeodactylum tricornutum, have antibacterial activity and the fatty acid, eicosapentaenoic acid (EPA), has been identified as one compound responsible for this activity. During the isolation of EPA, it became apparent that the extracts contained further antibacterial compounds. The present study was undertaken to isolate these additional antibacterial factors using silica column chromatography and reverse-phase high-performance liquid chromatography. Two antibacterial fractions, each containing a pure compound, were isolated and their chemical structures were investigated by mass spectrometry and nuclear magnetic resonance spectroscopy. The antibacterial compounds were identified as the monounsaturated fatty acid (9Z)-hexadecenoic acid (palmitoleic acid; C16:1 n-7) and the relatively unusual polyunsaturated fatty acid (6Z, 9Z, 12Z)-hexadecatrienoic acid (HTA; C16:3 n-4). Both are active against Gram-positive bacteria with HTA further inhibitory to the growth of the Gram-negative marine pathogen, Listonella anguillarum. Palmitoleic acid is active at micro-molar concentrations, kills bacteria rapidly, and is highly active against multidrug-resistant Staphylococcus aureus. These free fatty acids warrant further investigation as a new potential therapy for drug-resistant infections.     

Antibacterial activity of<Emphasis Type="Italic">Ulva lactuca</Emphasis> against methicillin-resistant<Emphasis Type="Italic">Staphylococcus aureus</Emphasis> (MRSA)

Thein vitro antimicrobial activity of the marine green algaeUlva lactuca was examined against gram-positive bacteria, gram-negative bacteria, and a fungus. The ethyl-ether extract of algae exhibited a broad-spectrum of antibacterial activity. but not antifungal activity againstCandida albicans. In particular, theU. lactuca extract showed strong activity aganst the bacterium methicillin-resistantStaphylococcus aureus (MRSA). This result confirms the potential use of seaweed extracts as a source of antibacterial compounds or as a health-promoting food for aquaculture.     

Evaluation and Risk Management by Using Ocimum bacillicum Against Waterborne Pathogens

Food and medicinal plants have been used for centuries against human diseases. The methanolic and aqueous extracts of different parts of Ocimum bacillicum Lam. (Niazboo or Sweet basil) of family Lamiaceae were investigated in vitro for their antibacterial properties against waterborne pathogens. The antibacterial properties of different parts of Ocimum bacillicum samples were assessed against Gram positive and Gram negative bacteria, which were isolated from water samples and identified by the API 20E method. The extracts from leaves and seeds of Ocimum bacillicum showed more antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, and E. coli at 37°C than those obtained from shoots, roots, and buds. The lowest minimum inhibitory concentrations and minimum bactericidal concentrations were observed for leaves and seeds as compared to other parts of the plant. No activity of alum was observed against the tested bacterial strains. The seeds of Ocimum bacillicum were associated with higher coagulation activity in comparison to other parts of the plant and were comparable with alum. These results suggest that parts of a plant offer a potential for antimicrobial treatment of drinking water, but needs further exploration.     

Benzyl isothiocyanate, a major component from the roots of Salvadora persica is highly active against Gram-negative bacteria

Plants produce a number of antimicrobial substances and the roots of the shrub Salvadora persica have been demonstrated to possess antimicrobial activity. Sticks from the roots of S. persica, Miswak sticks, have been used for centuries as a traditional method of cleaning teeth. Diverging reports on the chemical nature and antimicrobial repertoire of the chewing sticks from S. persica led us to explore its antibacterial properties against a panel of pathogenic or commensal bacteria and to identify the antibacterial component/s by methodical chemical characterization. S. persica root essential oil was prepared by steam distillation and solid-phase microextraction was used to sample volatiles released from fresh root. The active compound was identified by gas chromatography-mass spectrometry and antibacterial assays. The antibacterial compound was isolated using medium-pressure liquid chromatography. Transmission electron microscopy was used to visualize the effect on bacterial cells. The main antibacterial component of both S. persica root extracts and volatiles was benzyl isothiocyanate. Root extracts as well as commercial synthetic benzyl isothiocyanate exhibited rapid and strong bactericidal effect against oral pathogens involved in periodontal disease as well as against other Gram-negative bacteria, while Gram-positive bacteria mainly displayed growth inhibition or remained unaffected. The short exposure needed to obtain bactericidal effect implies that the chewing sticks and the essential oil may have a specific role in treatment of periodontal disease in reducing Gram-negative periodontal pathogens. Our results indicate the need for further investigation into the mechanism of the specific killing of Gram-negative bacteria by S. persica root stick extracts and its active component benzyl isothiocyanate.     

Evaluation of in-vitro antioxidant and antibacterial properties of Commelina nudiflora L. extracts prepared by different polar solvents

The study explored on the commonly available weed plant Commelina nudiflora which has potential in-vitro antioxidant and antimicrobial activity. The different polar solvents such as ethanol, chloroform, dichloromethane, hexane and aqueous were used for the soxhlet extraction. The extracts were identified pharmacologically as important bioactive compounds and their potential free radical scavenging activities, and antimicrobial properties were studied. C. nudiflora extracts were monitored on their in-vitro antioxidant ability by DPPH and ABTS radical scavenging assay. Aqueous extract shows significant free radical scavenging activity of 63.4 mg/GAE and 49.10 mg/g in DPPH and ABTS respectively. Furthermore, the aqueous crude extract was used in antibacterial studies, which shows the highest inhibitory activity against Pseudomonas aeruginosa, Escherichia coli and Salmonella typhi. Among all the extracts, aqueous extract of C. nudiflora has significant control over free radical scavenging activity and inhibition of the growth of food pathogenic bacteria. Also, the aqueous extract contains abundance of phenolics and flavonoids higher than other extracts. This study explored weed plant C. nudiflora as a potential source of antioxidant and antibacterial efficacy and identified various therapeutic value bioactive compounds from GC–MS analysis.Abbreviations: ABTS, 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid), DPPH, 2,2-diphenyl-1-picrylhydrazyl, GAE, gallic acid equivalent, GC–MS, gas chromatography and mass spectrometry     

Biological screening of traditional preparations from some medicinal plants used as antidiarrhoeal in Kinshasa, Congo.

Forty six aqueous extracts from 38 medicinal plant species belonging to different families were selected on the basis of their traditional medicinal use as antidiarrhoeic agents. They were submitted in a broad biological screening including antibacterial, antiamoebic and antispasmodic activities. The results of the testing have indicated that 37 extracts (80.43%), 33 (71.74%) and 32 (69.54%) exhibited some level of antibacterial, antiamoebic and antispasmodic activity respectively. Only 8 plant extracts (17.39%) would act as antidiarrhoeic agents by a triple pronounced antibacterial, antiamoebic and antispasmodic action. They include aqueous extracts from Euphorbia hirta whole plant, leaves of Psidium guajava and Tithonia diversifolia, root bark of Alchornea cordifolia, Heinsia pulchella, Paropsia brazzeana, Rauwolfia obscura and Voacanga africana.     

Antibacterial activity of aerial parts as well as in vitro raised calli of the medicinal plant Saraca asoca (Roxb.) de Wilde

Leaves, stem, and flowers of Saraca asoca, an endangered medicinal plant in India, and young explants cultivated on Murashige & Skoog's medium containing 6-benzylaminopurine were analyzed for antibacterial potential. Alcoholic and aqueous extracts from parent explants and their in vitro raised calli were tested by an agar well diffusion method. Minimal inhibitory concentrations (MICs) of the extracts were determined by broth microdilution method. Aqueous extracts showed antibacterial activity against limited bacterial species, whereas alcoholic extracts were active against a wider range of bacteria. Although the alcoholic extracts of all the explants and calli showed antibacterial activity, the extracts derived from flowers and their calli showed better results. Extracts derived from calli showed comparable results to the extracts from explants. Overall, the MICs of the extracts ranged from 0.039 to 1.25 mg/mL. MICs against gram-positive bacteria ranged from 0.078 to 1.25 mg/mL, whereas they ranged between 0.039 and 0.625 mg/mL against gram-negative bacteria. A MIC distribution plot showed that gram-negative bacteria were more susceptible to the extracts than gram-positive bacteria. It is concluded that extracts of S. asoca contain antibacterial agent, and as the calli gave good results, in vitro cultivation of the explants may be used to obtain antibacterial compounds. This is the first report on antibacterial activity of S. asoca, especially through in vitro raised calli.     

Study of antimicrobial activity and root symbionts of Hemionitis arifolia

Antibacterial and antifungal activity of crude extract, alcoholic extract and extracted phenol from various parts of tropical pteridophyta, Hemionitis arifolia were tested by agar diffusion and tube dilution assay. Both the crude and alcoholic extracts of vegetative and reproductive leaves of H. arifolia showed considerable antibacterial activity against Gram negative test strain of Escherichia coli (MTCC-739). Extract from reproductive leaves also showed moderate antibacterial activity against Bacillus subtilis (MTCC-441) (Gram positive test strain) but didn’t show any antifungal activity against Candida albicans (MTCC-7353). Mycorrhizal and other symbiotic association with the root system of H. arifolia was studied and it is revealed that a number of mycorrhizal strains were present in both vegetative and reproductive form. Presence of Dark Septate Endophytic Fungi (DSF) was also detected.     

Anticariogenic and phytochemical evaluation of Eucalyptus globules Labill.

In the present study, in vitro anticariogenic potential of ethyl acetate, hexane and methanol and aqueous extracts of plant leaves of Eucalyptus globules Labill. were evaluated by using four cariogenic bacteria, Lactobacillus acidophilus, Lactobacillus casei, Staphylococcus aureus and Streptococcus mutans. Agar well diffusion method and minimum inhibitory concentration (MIC) were used for this purpose. The ethyl acetate extracted fraction of plant leaves showed good inhibitory effects against all selected bacteria. In Eucalyptus globules, hexane and ethyl acetate extracts found highly effective against, Lactobacillus acidophilus with MIC value of 0.031 and 0.062 mg/mL, respectively. Qualitative phytochemical investigation of above extracts showed the presence of alkaloids, phenolic compounds, steroids, cardiac glycosides and terpenes. Based on the MIC value and bioautography, ethyl acetate of plant leaf was selected for further study. Further investigation on the structure elucidation of the bioactive compound using IR, GC-MS and NMR techniques revealed the presence of alpha-farnesene, a sesquiterpene. Eucalyptus globules plant leaf extracts have great potential as anticariogenic agents that may be useful in the treatment of oral disease.     

Assessment of Antibacterial Activity of Colebrookia oppositifolia against Waterborne Pathogens Isolated from Drinking Water of the Pothwar Region in Pakistan

An attempt was made to control waterborne pathogens by using medicinal plant extracts. One hundred and twenty-six water samples from filtration plants, tube wells, and water supplies were collected and analyzed for total and faecal Coliform bacteria as well as for total viable count. Results showed that waterborne pathogens were numerous and significantly higher than the World Health Organization's recommended guidelines. The methanolic and aqueous extracts of different parts of Colebrookia oppositifolia (Labiateae) were examined for antibacterial activities in vitro by an agar diffusion method. Antibacterial activity of leaves, shoots, and roots of Colebrookia oppositifolia was assessed against Gram positive and Gram negative bacteria that were isolated and identified from water samples by the API 20E method. Extract of roots showed more antibacterial activities against Staph. aureus and B. cereus var. mycoides, Pseudomonas aeruginosa, Klebsiella pneumonia, and Shigella flexneri at 37°C, than extracts from leaves and shoots. The lowest MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) were observed in roots as compared to shoots and leaves. These results suggest that there is an urgent need for improvement in existing water quality treatment. Secondly, the fruit extract can be practical for protection and to avoid risk of contamination by waterborne pathogens and to promote indigenous solutions for disease-control and environmental management.