Antimicrobial Activity Of Various Extracts Research Articles

Phytochemical analysis, antioxidant, and antimicrobial activities of Jordanian Pomegranate peels.

Pomegranate (Punica granatum) peels have shown numerous health benefits such as antioxidant, anti-inflammatory, and antimicrobial activities. These health activities are owed to the unique phytochemical components present in pomegranate peels. Variations in the pomegranate cultivar, geographical region, and extraction methods significantly affect the phytochemical composition and concentrations of pomegranate fruits and their peels, hence their health outcomes. Therefore, this study aimed to examine the phytochemical contents of pomegranate peels of Jordanian origin and their antioxidant and antimicrobial activities. Among the 6 extracts of pomegranate peels tested, the ethanol extract exhibited the highest total phenolic content (TPC = 297.70 ± 1.73 mg GAE/g DW), highest total flavonoids content (TFC = 116.08 ± 3.46 mg RE/g DW), highest hydrolyzable tannins (HT) contents (688.50 ± 3.54 mg TE/g DW). Whereas the highest condensed tannins (CT) content was found in both the ethanol (13.87 ± 0.58 mg CE/g DW) and methanol (13.84 ± 0.55 mg CE/g DW) extracts. For the antioxidant activities, the water extract of pomegranate peels displayed the highest inhibitory effect on DPPH radicals (9.43 ± 0.06 μmole TE/g DW), while for the ABTS+ assay the methanol and ethanol extracts exhibited the highest activities of 11.09 ± 0.02 and 11.09 ± 0.06 μmole TE/g DW, respectively. For the FRAP assay, the aqueous methanol extract exhibited the highest reducing activity (1.60 ± 0.09 mmole Fe (II)/g DW). As for the antimicrobial activities of various extracts of pomegranate peels, the highest antimicrobial activity against Micrococcus luteus was achieved by the ethanol extract (MIC = 6.25 mg/mL), whereas the lowest antimicrobial activity was observed against Candida krusei using the methanol extract (MIC = 100 mg/mL). These results indicate that pomegranate peels of Jordanian origin are rich in phytochemical content and exhibited strong antioxidant and antimicrobial activities making these agroindustrial by-products potential candidates for various medical applications and possible safe sources for important bioactive components.

Study on antimicrobial activity of various extracts of saxicolous lichen Lecanora Muralis

Antimicrobial activity of aqueous, acetone, methanol, and ethanol extracts of saxicolous lichen Lecanora muralis sampled from Odzun, Lori province of Armenia were studied. Aqueous extract was not demonstrated any significant antibacterial activity neither Gram positive nor Gram negative bacteria. All other extracts exhibited antimicrobial activity only against only tested Grampositive bacteria. The minimal inhibitory concentration (MIC) value of acetone extract was 57 μg/μl against Bacillus subtilis.

The Proximate Analysis, Mineral Composition, Phytochemical Screening and Antimicrobial Activity of Ripe and Unripe Peel Extract of Musa Paradisiaca

Background/Objectives: Musa paradisiaca (Plantain) is used as a traditional therapeutic medicinal plant employed in various diseases. This study was carried out to evaluate the nutraceutical potentials of the ripe and unripe peels of Musa paradisiaca. The phytochemical screening as well as antimicrobial activity of various extracts (methanol and ethanol) of ripe and unripe peels of Musa paradisiaca was also evaluated. Methods: Proximate and mineral analyses of the samples were performed as per the standard methods of the Association of Official Analytical Chemists. Preliminary phytochemical screening of methanol and ethanol extracts of the peels was also carried out in accordance with standard methods. The antimicrobial activities of methanol and ethanol extracts of M. paradisiaca peel were tested in-vitro against isolates of clinical origin by agar well diffusion method. Results: Phytochemical analysis of both peel extracts indicated the presence of flavonoids, terpenoids, starch, steroids, and reducing sugars. The mineral analysis indicated the presence of essential minerals such as iron, zinc, copper and manganese. The fat, protein, crude fibre and carbohydrate composition values of the unripe peel extract were found higher than the ripe samples. The ethanol and methanol extracts of both the ripe and unripe peels of M. paradisiaca used at various concentrations showed no antibacterial activities against the organisms. Conclusion: This study concludes that ripe and unripe plantain fruit peels thought to be of little or no significance could serve as nutraceuticals and a medicinally vital material in animal health and probably humans.

Antioxidant and Antimicrobial Activities of Various Extracts from Safou (Dacryodes edulis) Cultivated in Côte d’Ivoire

Safou (Dacryodes edulis) is a fruit with very interesting nutritional and pharmacological properties. However, this fruit remains rather unknown to the Ivorian population.
 Aims: The objective of this study was to highlight the antioxidant and antimicrobial potential of the seed and pulp of Safou (Dacryodes edulis) cultivated in Côte d'Ivoire for its valorization.
 Study Design: Microbiological and biochemical studies
 Place and Duration of Study: Laboratory of Biotechnology and Food Microbiology,Abidjan, Côte d’Ivoire, between September 2020 and February 2021.
 Methodology: Aqueous, ethanolic and methanolic extracts of the pulp and seed of Safou were prepared. Moisture content, pH, yield, total polyphenols,diphényl-2-picrylhydrazyle (DPPH) radical scavenging testof the different extracts were determined.Aqueous, ethanolicand methanolicextracts of the seed and pulp at varying concentrations of 200 mg/mL, 100 mg/mL, 50 mg/mL, 25 mg/mL, 12.5mg/mL and 6.25 mg/mL was tested against human pathogens such asEscherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiellapneumoniae, Proteus mirabilis, Aspergillus fumigatus and Penicilliumchrysogenum.
 Results: pH, moisture content and yield ranged from 3.16 to 4.74; 9 to 18.30%; and 10.79 to 18.78%, respectively. Total polyphenol content ranged from 1.45 mgEAG/g to 4.56 mgEAG/g. The highest levels of total polyphenols were observed for the methanolic extracts of pulp. The different extracts strongly scavenged the DPPH radical with percentages of anti-free radical activity that varied from 50.76 to 64.43%.The antimicrobial susceptibility results of the methanolic extracts of D. edulis seed showed highest zones of inhibition to the microbial isolates tested. The microorganisms were resistant to the aqueous extracts of pulp and seed.
 Conclusion: The presence of bioactive compounds and the antimicrobial activity of Safou extracts could justify its use in the food and pharmaceutical fields.

Phytochemical Screening and Antimicrobial Activity of Various Extracts of Aerial Parts of Rhanterium epapposum

Rhanterium epapposum, native to the Arabian Peninsula, is traditionally used to cure skin infections. The objective is to screen the phytochemical content and antimicrobial activity of aqueous, methanol and 80% methanol extracts of aerial parts of R. epapposum. The phytochemical screening of aqueous, methanolic, and 80% methanol extracts of R. epapposum was conducted using gas chromatographymass spectrometry. The antimicrobial activities of the extracts were assessed by well diffusion and microdilution methods. Qualitative phytochemical analysis revealed the presence of 2-methoxy-4-vinylphenol in all three extracts, whereas ethanol, 2-methoxy-, acetate; n-hexadecanoic acid; and 2,3-butanediol are present in higher amount exclusively in the methanol, 80% methanol and aqueous extracts of the aerial parts of R. epapposum, respectively. The highest antibacterial activity was shown by the aqueous extract S. aureus, P. aeruginosa, E. cloacae, and K. pneumoniae, methanolic extract against S. aureus, methicillin-resistant S. aureus, and E. coli, and 80% methanol extract against S. epidermidis, and S. paucimobilis. Interestingly, 80% methanol extracts showed the highest antifungal activity against C. albicans, C. guillermondii, C. vaginalis, C. utilis, and C. tropicalis. The aerial parts of R. epapposum showed broad-spread antimicrobial activity against bacteria and fungi. Especially, the 80% methanol extract showed potent antifungal activity against all the tested fungal strains.

Phytochemical Evaluation, Antioxidant and Antimicrobial Activities of Various Extracts from Leaves and Stems of Bryophyllum pinnatum

Antioxidant and antimicrobial activities of different extracts (methanol and ethyl acetate) of leaf and stem of Bryophyllum pinnatum were studied. The screening for the secondary metabolites was carried out using the standard methods. The antioxidant capacities of the different extracts were assessed using DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and Ferric reducing antioxidant power (FRAP) while the antimicrobial activity of the extracts obtained were screened against Gram-positive, Gram-negative bacteria and fungi (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa Salmonella spp., Vibrio cholerae, Candida albicans and Aspergillus niger) using Agar well diffusion method. Both extracts obtained from leaf and stem of Bryophyllum pinnatum contained most of the phytochemical compounds tested for. However, anthocyanins and anthraquinone were not detected in leaf extracts while coumarin was absent in stem extracts. Quantification of bioactive compounds showed that both extracts contained the highest concentration of polyphenols (34.49 ±0.47 mg GAE/g and 32.32 ±1.2 mg GAE/g for methanol leaf and stem extracts respectively) while the least concentration was recorded for alkaloids (0.03±0.02 mg/g for methanol stem extract). Results revealed that the extracts showed dose-dependent scavenging of DPPH as well as the ability of the extracts to reduce FeCl3 solution, with methanol extracts exhibiting the highest scavenging and reducing capacity. However the leaves of Bryophyllum pinnatum had greater antioxidant activity than the stem by DPPH and ferric reducing assays, with IC50 values ranging from 3.147µg/ml to 3.80µg/ml for DPPH and 331.9 - 451 µg/ml for FRAP assays. The antimicrobial activity of various solvent extracts of leaf and stem reveal that microorganisms exhibited different sensitivities towards these extracts in a dose-dependent manner. Methanol leaf extract showed no activity against Escherichia coli while Pseudomonas aeruginosa was insensitive to ethyl acetate leaf extract. For stem extracts, Aspergillus niger, Vibrio cholerae and Pseudomonas aeruginosa were resistant to methanol extract while Aspergillus niger, Salmonella spp. and Pseudomonas aeruginosa was resistant towards ethyl acetate stem extract. The results obtained in this study showed that Bryophyllum pinnatum is a reservoir of bioactive compounds and both extracts exhibited significant antimicrobial and antioxidant activity.

Antimicrobial activity of various extracts of Sargassum glaucescens on the antibiotic resistant organisms

The antimicrobial activity of brown alga methanol, ethyl acetate, hexane, and chloroform extracts on bacteria Gram positive, Gram negative, and fungi was evaluated by using nutrient broth macrodilution test. Sargassum glaucescense was collected around the coastal area of Chabahar (south of Iran) protected marine area of the Oman sea in April and May 2015. Six pathogenic organisms including; Enterococcus faecium ATCC 51299, Streptococcus mutans ATCC 35668, Shigella boydii ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 13883, Salmonella enteritidi PTCC, 1709, Candida albicans ATCC 10231 and Aspergillus fumigatus PTCC 5009 were investigated by the broth dilution method. Methanolic Extract for six strains showed good activity amongst eight strains. Hexane extract, after methanolic extract has good effect on antimicrobial activity against five strains. All bacteria strain in this survey has showed resistance against ethyl acetate and chloroformic extracts. S. glaucescens using four various solution extract against eight different human pathogens showed an important antimicrobial and antifungal activity. However, more investigation has to be done on separation, purification and detection of the active ingredients in order to recognize their antifungal and antifungal activity.

Screening of Antimicrobial Activity of Various Extracts of the Stem Justicia gendarussa

Objective: The present study was designed to check in-vitro efficacy of Antibacterial and antifungal activity of aqueous and hexane extracts of stem of Justicia gendarussa against selected bacterial and fungal strains. Justicia gendarussa, belonging to the family Acanthaceae, commonly known as ‘‘vatham kolli’ was used in treatment of bronchitis, inflammation, eye diseases, ear ache, vaginal discharges, rheumatism, dysentery, eczema and jaundice.
 Methodology: Hexane and aqueous extracts of Justicia gendarussa was used for antimicrobial screening. Antibacterial activity was tested against pathogenic bacterial strains Eschericha coli and Staphylococcus aureus. Also antifungal activity was tested against one human pathogenic fungal strain i.e. Candida albicans. Antibacterial and antifungal activities of Justicia gendarussa extract was carried out by using disc diffusion method.
 Results: Aqueous extract of Justicia gendarussa showed the largest zone of inhibition (5mm) against Eschericha coli, at 50µgm/ml and 3mmzone of inhibition against S. aures, at 50µgm/ml. Hexane extract does not showing activity against to human pathogenic E. coli and S. aures, at 50µgm/ml. Aqueous extract has shown more potent antibacterial activity against Eschericha coli. Aqueous extract was found to be more effective against human pathogenic fungus Candida albicuns than hexane extract and standard drug. The zone of inhibition of Aqueous extract was 11mm and the zone of inhibition of hexane extract was7mm and standard only 2mm.The phytochemical screening demonstrated the presence of different types of compounds like terpenoids, tannins, and flavonoids which may contribute for the anti-microbial action of this plant.
 Conclusions: These findings provide scientific evidence of traditional use of Justicia gendarussa and also indicate the potential of this plant for the development of antimicrobial agents.

Phytochemical and Antimicrobial Activities of Bryophyllum pinnatum and Vernonia amygdalina Leaves Extracts on Selected Microbial Isolates from Wound Infection

Introduction: The therapeutic actions of plants may be due to the presence of some phytochemical components. Due to the increasing emergence of multi antibiotics resistance, wound pathogens are causing huge public health concerns. There is need for exploring some necessary alternatives for treatment of wound infections.
 Aim: This study investigated the phytochemical and antimicrobial activities of Vernonia amygdalina and Bryophyllum pinnatum leaves extracts on Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus isolates from wound infection.
 Methodology: The fresh leaves of both plants were extracted using Sofowora method and the phytochemicals were screened. Different concentrations of the extract, antibiotic and ethanol were tested against the isolates using disc diffusion technique.
 Results: Alkaloids, flavonoids, tannins, anthraquinone and fixed oils were present in the both plant extracts but saponins were only found in V. amygdalina and cardenolide were only in B. pinnatum. Quantitatively, all the phytochemicals investigated in the study were present with V. amygdalina having the highest level of saponins than Bryophyllum pinnatum (P<0.05) and low steroids with P=0.2879 (P>0.05).The crude extract of V. amygdalina had the highest zone of inhibition compared to aqueous and ethanol extracts at 75 mg/ml concentration (P<0.05) but generally, the ethanol extracts of both plants had more inhibitions at varying concentrations. Thus comparing the antimicrobial activity of various extracts of both plants on the wound isolates and the controls (antibiotics and ethanol), there was significant variation in their zones of inhibition produce (P<0.05).
 Conclusion: The results show that the zone of inhibition increases with the concentrations of the extracts. Therefore, the antimicrobial effect of these plants may depend on the concentration of the extract and the solvent used for extraction. This study showed that B. pinnatum and V. amygdalina could be used as an alternative therapy to antibiotics to treat wound infection caused by P. aeruginosa, E. coli and S. aureus.

Antibacterial activity of lt;emgt;Sclerocaryalt;/emgt; lt;emgt;Birrealt;/emgt; on some urinary tract infections (UTI) pathogens

For many years, human population across the world utilizes environmental resources such as plants to treat infectious diseases. The study was aimed to determine the phytochemical constituents and antimicrobial activity of various extracts of S. birrea against some bacteria associated with urinary tract infections (UTIs). Four (4) clinical isolates (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella) isolated from urine samples collected from patients with urinary tract infections attending Abubakar Imam Urology Hospital Kano, Northern Nigeria were tested against aqueous and methanol extracts of Sclerocarya birrea stem bark using agar well diffusion method. The qualitative and quantitative phytochemical screening of the extract was conducted using conventional laboratory methods. The result showed that the stem bark extract of Sclerocarya birrea contain saponin, phenol, terpenoid, alkaloid, flavonoid, anthraquinones and tannin. Quantitatively, flavonoid was found to be the most abundant constituent making about 16.5% followed by phenol 12.5%. The result of antibacterial activity of the extracts against the test isolated indicated that the extracts were active against the isolate with higher activity shown by methanol extract (13.5 mm) when compared to aqueous extract (11.4 mm). Escherichia coli was found to be the most sensitive isolate (13.8 mm) while Pseudomonas aeruginosa is the least susceptible to the isolate (12.3 mm). However, the differences in the sensitivity of the isolates to the extracts is not significant at p<0.05. It is concluded that the stem bark extracts of Sclerocarya birrea is active against some bacterial isolates associated with UTI.

In Vitro Antimicrobial Activity and GC–MS Findings of the Gel of Aloe vacillans Forssk. of Abha Region, Saudi Arabia

A great variety of weeds grow in the Abha area, Saudi Arabia, at more than 2700 m above sea level. The aim of this study was to evaluate the antimicrobial activities of various extracts of fresh and dry leaf gel of Aloe vacillans against eight clinical isolates of human pathogens. The chemical compounds present in the gel extract were identified and quantified by gas chromatography–mass spectrometry. Solvent extracts inhibited 62.5% of the examined microbes, whereas the fresh leaf extract was more potent and active against Staphylococcus aureus, Micrococcus luteus, Klebsiella oxytocam, Proteus mirabilis, and Candida albicans compared to the dry leaf extract. No antimicrobial activities were observed against Klebsiella pneumonia, Shigella flexneri, and Pseudomonas aeruginosa. Candida albicans was the most susceptible pathogen based on its zone of inhibition. The maximum inhibitory activities were shown by the fresh gel of the chloroform extract against M. luteus, the methanol extract against S. aureus, the petroleum ether extract against P. mirabilis, C. albicans, and K. pneumoniae, and hot water extracts against K. oxytocam. Gram-positive bacteria and C. albicans were more susceptible than gram-negative bacteria. Compounds were identified and quantified; the major constituents of the gel were 1,3-dimethoxy-2-propanol and glycerol. Acetoglycerides, ethanol, 5-(hydroxymethyl)-2-furaldehyde, palmitic acid, butane, 1,2:3,4-diepoxy-,(. $$+/-$$ .)-, 2-deoxy-d-galactose, butyl acetate, 2,2-dimethoxyethanol, diethyl phthalate, phytol, octadecanoic acid, gamma-linolenic acid, and stearic acid were present in low amounts. Therefore, because of its antimicrobial activities and useful phytochemical composition, A. vacillans leaf gel is a promising pharmaceutical drug for specific microbial infections and for improving health.

Evaluation of antioxidant and antimicrobial activity of various extracts of Buxus wallichiana Baill wood

The present study was designed to evaluate the antioxidant and antimicrobial activity of various extracts of Buxus wallichiana Baill wood. Extraction of wood was done by hot continuous percolation process by using suitable solvents and the concentrated extract was used for the study. Anti oxidant Activity is done by in vitro DPPH (2, 2-diphenyl-1-picryl hydrazyl) method and Nitric oxide radical inhibition activity method, where Antibacterial Activity is done by Cup Plate Method. The MEBW (Methanolic extract of Buxus wallichiana) showed an IC50 value of 29.2±2.10, where as ABBW (Aqueous extract of Buxus wallichiana), CEBW(cholroform extract of Buxus wallichiana) and PEBW (Petroleum ether extract of Buxus wallichiana) produced IC50 values of 190±5.33, 647.5±16.43 and 747.5±10.2 respectively in DPPH method. When assayed for Antibacterial Activity MEBW at 500 μg/ml produced zone of inhibition of 26mm against Klebsiella aerogenes organism, against proteus vulgaris organism, CEBW, AEBW at 500 μg/ml produced zone of inhibition of 19mm. Against bacillus premiles, b. aerogenes and b.coacoagulans MEBW at 500 μg/ml shown zone of inhibition of 17, 19 and 24 mm respectively. The result of this study reveal that Buxus wallichiana Baill could be considered as potential source of natural anti oxidant and anti bacterial plant.

Antimicrobial activities of various extracts of Coriolus versicoloragainst oral bacteria

Antimicrobial activities of various extracts of Coriolus versicoloragainst oral bacteria

Antimicrobial activity of various extracts of Plectranthus ambionicus and Phyllanthus amarus

Hexane, chloroform, ethyl acetate and methanol extracts of leaves of Plectranthus ambionicus and Phyllanthus amarus were screened for their antimicrobial activity against human pathogenic bacterial and fungal strains. Antimicrobial activity was carried out by disc diffusion method, determination of minimum inhibitory concentrations (MIC), minimum bactericidal concentrations (MBC) and minimum fungicidal concentrations (MFC) against four strains of Gram positive bacteria, three strains of Gram negative bacteria and three species of fungi. The antimicrobial activity of various extracts of Plectranthus ambionicus and Phyllanthus amarus showed varied levels of antimicrobial activity against the studied bacterial and fungal pathogens. The mean zone of inhibition produced by all the tested extracts ranged from 7.0 ± 0.50 mm to 29.5 ± 0.50 mm. The MIC, MBC and MFC values were between 15.62 and 1000 μg/mL. The ethyl acetate extract of Plectranthus ambionicus showed good antimicrobial activity with the highest mean zone of inhibition (29.5±0.5 mm), lowest MIC (15.62 μg/mL) and MBC (31.25 μg/mL) values followed by ethyl acetate extract of Phyllanthus amarus(23.6±0.50 mm; MIC=62.5; MBC=125 μg/mL) against Aspergillus fumigates.

Acute and Subchronic Toxicities of Indonesian Mistletoes Dendrophthoe pentandra L. (Miq.) Ethanol Extract

Antimicrobial activity of various extracts from various parts of Calophyllum inophyllum L.Saravanan. R, Dhachinamoorthi. D, Senthilkumar. K, Thamizhvanan. K.

Acute Toxicity Studies and Evaluation of Analgesic Property of the Methanol Stem Bark Extract of Neocarya macrophylla

Antimicrobial activity of various extracts from various parts of Calophyllum inophyllum L.Saravanan. R, Dhachinamoorthi. D, Senthilkumar. K, Thamizhvanan. K.

English

The aim of the present study is to determine the in vitro antimicrobial activity of various extracts and fractions of Muntingia calabura (Elaeocarpaceae) root against a selected panel of microorganisms. Antifungal activity of different solvent extracts of M. calabura L. root, tested against Alternaria solani, Fusarium oxysporum f.sp. lycopersici, Pythium species, Phytophthora species, Aspergillus niger, Colletotrichum species and Rhizoctonia solani, was evaluated by agar well diffusion assay. The chromatographic fractionation of the extract resulted in the isolation of antifungal metabolite stigmasterol. The structure of the stigmasterol was confirmed using GC-MS, IR and NMR spectroscopic characterization. The stigmasterol had a potent antifungal activity with a minimum inhibitory concentration of 1 mg/ml against A. solani. Stigmasterol was subjected to docking studies carried out against fungal elicitor cryptogein. A better docking score of 12.59 with glide energy -42.56 was obtained for the complex fungal elicitor cryptogein. The interaction was done in chain A Tyr 47 [O – H…O] residue with a distance of 2.7 A°. Key words: Muntingia calabura, minimum inhibitory concentration, phytopathogens, cryptogein elicitor, stigmasterol.

English

The present study was conducted to evaluate the antimicrobial activity of various extracts (viz. methanol, acetone and ethyl acetate) of Thuja orientalis and its preliminary phytochemical screening. In vitro antimicrobial activity was tested by agar well diffusion assay against human pathogenic microbes which are Gram positive (viz. S. aureus andB. subtilis), Gram negative bacteria (viz. P. aeruginosa, A. faecalis and K. pneumoniae) and fungi (A. flavus and A. niger). Methanol and acetone extract of leaf exhibited maximum activity against B. subtilis with zones of inhibition of 20.33 mm and 17.83 mm, respectively. All the extracts of stem were found to be most effective against P. aeruginosa. S. aureus was found to be sensitive to leaf extracts prepared in methanol, acetone and ethyl acetate with 13.66, 14.03 and 15.00 mm zone of inhibition, respectively.A. flavus and A. niger, both were found to be sensitive towards the methanol extract of leaf with inhibition zones of 15.50 and 16.00 mm, respectively compared to fungicides (viz. ketoconazole and fluconozole). Methanol extract of leaf and ethyl acetate extract of stem exhibit marked antimicrobial activity against B. subtilis and P. aeruginosa, which was comparable to standard antibiotics (that is, penicillin, ampicillin, tetracycline and streptomycin). It was also observed that leaf extracts were more effective as compared tostem extracts of the plant. Thus, Thuja orientalis could be considered as potential source of natural antimicrobials used for the treatment of bacterial and fungal infections.   Key words: Plant extracts, antibacterial activity, minimal inhibitory concentration, phytochemical screening.

Chemical composition and antimicrobial activity of various extracts of O. gratissimum L. from Guilan, Iran

The in vitro antimicrobial activities of crude ethanol, methanol and water extracts of the stem bark of O. gratissimumwere investigated. The extracts exhibited 52 M. R. M. Khoshkholgh Pahlaviani et al antimicrobial activities with zones of inhibition ranging from 10 to 20, 7 to 14 and 2 to 7mm for methanol, ethanol and water extracts respectively. The minimum inhibitory concentration (MIC) of the methanol extract was between 0.5 and 10 mgml -1 while that of ethanol extract ranged from 0.5 to 20 mgml -1 ,while MIC and MBC of streptomycin (Control strain) ranged between 0.065 and 0.5 mgml-1 for all tested bacteria. The minimum bactericidal concentration (MBC) for methanol extract ranged between 2.0 and 12.50 mgml-1, while that of ethanol ranged from 2.0 to 20 mgml-1. Again all the extracts exhibited appreciable activity against all the fungal species investigated. The zones of inhibition exhibited by the extracts against the test fungal species ranged between 2 and 9 for water, ethanol and methanol extracts respectively. Phytochemical screening revealed the presence of saponin, steroids, tannins, glycosides, alkaloids and flavonoids in the extracts. The ability of the crude stem extracts of O. gratissimum to inhibit the growth of bacteria is an indication of its broad spectrum antimicrobial potential which may be employed in the management of microbial infections.

Screening antimicrobial activity of various extracts of Urtica dioica

Urtica dioica or stinging nettle is traditionally used as an herbal medicine in Western Asia. The current study represents the investigation of antimicrobial activity of U. dioica from nine crude extracts that were prepared using different organic solvents, obtained from two extraction methods: the Soxhlet extractor (Method I), which included the use of four solvents with ethyl acetate and hexane, or the sequential partitions (Method II) with a five solvent system (butanol). The antibacterial and antifungal activities of crude extracts were tested against 28 bacteria, three yeast strains and seven fungal isolates by the disc diffusion and broth dilution methods. Amoxicillin was used as positive control for bacteria strains, vancomycin for Streptococcus sp., miconazole nitrate (30 microg/mL) as positive control for fungi and yeast, and pure methanol (v/v) as negative control. The disc diffusion assay was used to determine the sensitivity of the samples, whilst the broth dilution method was used for the determination of the minimal inhibition concentration (MIC). The ethyl acetate and hexane extract from extraction method I (EA I and HE I) exhibited highest inhibition against some pathogenic bacteria such as Bacillus cereus, MRSA and Vibrio parahaemolyticus. A selection of extracts that showed some activity was further tested for the MIC and minimal bactericidal concentrations (MBC). MIC values of Bacillus subtilis and Methicillin-resistant Staphylococcus aureus (MRSA) using butanol extract of extraction method II (BE II) were 8.33 and 16.33mg/mL, respectively; while the MIC value using ethyl acetate extract of extraction method II (EAE II) for Vibrio parahaemolyticus was 0.13mg/mL. Our study showed that 47.06% of extracts inhibited Gram-negative (8 out of 17), and 63.63% of extracts also inhibited Gram-positive bacteria (7 out of 11); besides, statistically the frequency of antimicrobial activity was 13.45% (35 out of 342) which in this among 21.71% belongs to antimicrobial activity extracts from extraction method I (33 out of 152 of crude extracts) and 6.82% from extraction method II (13 out of 190 of crude extracts). However, crude extracts from method I exhibited better antimicrobial activity against the Gram-positive bacteria than the Gram-negative bacteria. The positive results on medicinal plants screening for antibacterial activity constitutes primary information for further phytochemical and pharmacological studies. Therefore, the extracts could be suitable as antimicrobial agents in pharmaceutical and food industry.