Activity-directed fractionation and isolation of four antibacterial compounds from Abrus precatorius L. roots

Root extracts of the plant Abrus precatorius L. was tested for antibacterial activity. Various solvent fractions exhibited inhibitory activity against 13 gram-positive and gram-negative bacteria. Root extracts were analyzed by thin layer chromatography. The antibacterial activity was localized to specific chromatophores in the chloroform fraction through a bioautography assay. It was found localized to 4 chromatophores out of 7. The chromatophores were isolated from the TLC plates and rechecked for activity against Staphylococcus aureus A, using a disc diffusion assay. Among the four active principles isolated, AP 3 (Rf 0.87) exhibited maximum activity, i.e., 56% inhibition of growth of S. aureus A, in disc diffusion assay compared to the standard antibiotic Ampicillin. Results of this study suggest that chloroform extractable phytochemicals in A. precatorius L. may yield promising molecules with antibiotic activity.     

Antimicrobial activity of three baccharis species used in the traditional medicine of Northern Chile

The antimicrobial activities of aqueous ethanol and chloroform extracts of three Baccharis species currently used in Northern Chile folk medicine for the treatment of several infectious and inflammatory disorders were tested against Gram-positive and negative bacteria and fungal spp. using the agar-disc diffusion assay. The results indicated that the activity was more pronounced against Gram-positive than against Gram-negative bacteria and yeast. No significant differences on the antibacterial activity were observed in the aqueous ethanol versus chloroform extracts. None of the plant extracts evaluated exhibited any activity against ten fungi tested.     

Antibacterial activity of three medicinal Thai plants against Campylobacter jejuni and other foodborne pathogens

Leaves of Adenanthera pavonina, Moringa oleifera and Annona squamosa are used in traditional Thai medicine to treat dysentery and other diseases. This study investigated the antibacterial activity of these plants against six species of foodborne pathogen. Methods and solvents employed to extract active constituents were optimised using the disc diffusion assay. Phytochemical analysis of the optimised extracts was performed by thin layer chromatography (TLC). Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined by broth microdilution. A. pavonina contained flavonoids, terpines and tannins, and was the most active extract against Campylobacter jejuni, inhibiting growth at 62.5-125 μg mL(-1). The A. squamosa extract contained flavonoids, terpines, tannins and alkaloids, and had the broadest spectrum of antibacterial activity, inhibiting Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus and C. jejuni between 62.5 and 500 μg mL(-1). MBCs were 2- to 4-fold higher than MICs against C. jejuni and B. cereus, suggesting the extracts are bactericidal against these species. Negligible activity was detected from M. oleifera. The data presented here show that A. pavonina and A. squamosa could potentially be used in modern applications aimed at the treatment or prevention of foodborne diseases.     

Free radical scavenging, antimicrobial and immunomodulatory activities of Orthosiphon stamineus

Orthosiphon stamineus is considered an important traditional folk medicine. In this study ethanol and aqueous extracts of O. stamineus were evaluated in vitro for their antioxidant, antimicrobial as well as for their immunomodulatory properties on human peripheral blood mononuclear cells (PBMCs). The DPPH radical scavenging method was used for the determination of antioxidant activity, while the antibacterial efficacy was investigated by both disc diffusion method and Minimum Inhibitory Concentration (MIC) against four bacterial strains (Gram-positive and Gram-negative). Furthermore, the immunomodulatory potential of the extracts was investigated through the MTT assay. Aqueous extract of O. stamineus exhibited significant free radical scavenging activity with IC?? 50 9.6 μg/mL, whereas the IC?? for the ethanol extract was 21.4 μg/mL. The best antimicrobial activity was shown by the aqueous extract of O. stamineus against Staphylococcus aureus, with inhibition zone of 10.5 mm and MIC value 1.56 mg/mL. Moreover, the results observed from the MTT assay showed that both plant extracts stimulated the PBMCs proliferation in vitro in a concentration-dependent manner, but the aqueous extract has remarkable activity against PBMCs. These findings indicate that O. stamineus showed high antioxidant activity and may be considered as an immunomodulatory agent.     

Antibacterial and cytotoxic activities of the sesquiterpene lactones cnicin and onopordopicrin

The antimicrobial and cytotoxic activities of chloroform extracts from the weeds Centaurea tweediei and C. diffusa, and the main sesquiterpene lactones isolated from these species, onopordopicrin and cnicin, respectively, were assayed. Results show that the chloroform extracts from both Centaurea species possess antibacterial activities against a panel of Gram-positive and Gram-negative bacteria. Remarkable antibacterial activity against methicillin-resistant Staphylococcus aureus was also measured. Both the extracts and the purified sesquiterpene lactones show high cytotoxicity against human-derived macrophages. Despite this cytotoxicity, C. diffusa chloroform extract and cnicin are attractive candidates for evaluation as antibiotics in topical preparations against skin-associated pathogens.     

Phytochemical screening, antibacterial activity and in vitro interactions between Costus cf. arabicus L. with UV-A and aminoglycosides

In this study, the methanol extracts of of Costus cf. arabicus L. were evaluated for antibacterial activity against multiresistant strains of Escherichia coli and Staphylococcus aureus. The antibacterial and modulatory activity of the extracts was assayed by microdilution. The light-enhanced antibacterial activity was assayed by light regimen. The growth of the bacteria tested was not inhibited by the extracts. The minimum inhibitory concentration (MIC) values ranged from 512 to ≥1024 μg·m L(-1). However, the antibiotic activity of the aminoglycosides was synergistically enhanced when these extracts were associated in sub-inhibitory concentrations with the antibiotics. Both extracts showed activity against at two standard bacterial strains. Because of this, we suggest that the ethanol extracts of the stems and leaves of Costus cf. arabicus L. show potential antibacterial, light-induced and synergistic antibiotic activity. With such results, these extracts are proven to be a promising source of antibacterial and modulatory agents.     

Chemical investigation of Finlaysonia obovata: part I--a rare triterpene acid showing antibacterial activity against fish pathogens

The antibacterial screening of extracts of the leaves of Finlaysonia obovata with hexane, chloroform and alcohol was carried out against fresh water fish pathogenic bacteria viz., Micrococcus Sp. (multidrug resistant strain), Aeromonas hydrophila, Pseudomonas aeruginosa, Vibrio alginolyticus, Staphylococcus aureus, Escherichia Coli, Edwardsiella tarda by disc-assay method. The hexane and chloroform extracts were found active against four and five pathogens, respectively. The highly active chloroform extract was taken up for fractionations, further screening and isolation of secondary metabolites by chromatographic techniques. The triterpene acid Urs-3beta-hydroxy-12-en-27-oic acid (3), which is very rarely found from plant sources is isolated first time from this plant along with known compounds; Lupeol acetate (1) and beta-Sitosterol (2). This article presents for the first time all the spectral data for Urs-3beta-hydroxy-12-en-27-oic acid (3), which showed moderate activity against four pathogens. This is the first report of antibacterial activity of a triterpene against fish pathogens.     

Isolation and identification of an anti-tumor component from leaves of Impatiens balsamina

We have previously shown that ethanol or chloroform extracts of the leaves of Impatiens balsamina (LIB) have anti-tumor activity against the human hepatocellular carcinoma cell line HepG2. The ethanol extracts were separated into five fractions according to polarity. An MTT assay indicated that two of the fractions had anti-tumor activity and that the petroleum ether fraction (PEF) was the most active. But the available quantities of both the PEF and chloroform fractions (CHF) were limited, precluding further study. The chloroform extract (CHE) shared almost all the same spots with the PEF and CHF and was plentiful enough to carry out further separations. Thus, the CHE was further separated into six sub-fractions (CHE 1 approximately 6) by column chromatography. A MTT assay showed that only the CHE2 fraction had a strong tumor inhibition ratio (IC(50) = 6.47+/-0.05 mg/L), which was superior to that of curcumin (IC(50) = 13.95+/-0.11 mg/L). However, TLC revealed that CHE2 was not pure and still contained two more components. After further separation and purification, followed by TLC and MTT assay confirmation, the final active component was isolated and identified as 2-methoxy-1,4-naphthoquinone by m.p., UV, MS and (13)C- and (1)H-NMR data. This is the first report demonstrating that 2-methoxy-1,4-naphthoquinone has intensive in vitro anti-tumor activity against HepG2 cells.     

Antimicrobial activity of Blumea balsamifera (Lin.) DC. extracts and essential oil

Leaves of Blumea balsamifera (Lin.) DC. are used in traditional Thai and Chinese medicine for the treatment of septic wounds and other infections. In this study, the essential oil, hexane, dichloromethane and methanol extracts of these leaves were evaluated for antibacterial and antifungal activities using the disc diffusion assay and agar microdilution method. The essential oil was the most potent, with a minimum inhibitory concentration (MIC) of 150?μg?mL?1 against Bacillus cereus and an MIC of 1.2?mg?mL?1 against Staphylococcus aureus and Candida albicans. Activity was also detected from the hexane extract against Enterobacter cloacae and S. aureus. Minimum bactericidal and fungicidal concentrations were typically equal to or two-fold higher than the MICs for both extracts, indicating microbicidal activity. The present data show that B. balsamifera extracts have activity against various infectious and toxin-producing microorganisms. This plant's active constituents could potentially be developed for use in the treatment and/or prevention of microbial disease.     

Synthesis, characterization and antibacterial activity of azomethine derivatives derived from 2-formylphenoxyacetic acid

A series of eight new azomethine derivatives were synthesized by reacting 2-formylphenoxyacetic acid with aromatic amines. The chemical structures of these compounds were confirmed by means of 1H-NMR, 13C-NMR, MS and elemental analysis. The compounds were assayed by the disc diffusion method for antibacterial against Staphylococcus aureus and Escherichia coli. Among the compounds tested, 2a, 2b, 2e, 2g and 2h exhibited good antibacterial activity, almost equal to that of Ciprofloxacin used as standard.     

Chemical constituents and antibacterial activity of Melastoma malabathricum L

The aqueous methanolic extracts of Melastoma malabathricum L. exhibited antibacterial activity when assayed against seven microorganisms by the agar diffusion method. Solvent fractionation afforded active chloroform and ethyl acetate fractions from the leaves and the flowers, respectively. A phytochemical study resulted in the identification of ursolic acid (1), 2α-hydroxyursolic acid (2), asiatic acid (3), β-sitosterol 3-O-β-D-glucopyranoside (4) and the glycolipid glycerol 1,2-dilinolenyl-3-O-β-D-galactopyanoside (5) from the chloroform fraction. Kaempferol (6), kaempferol 3-O-α-L-rhamnopyranoside (7), kaempferol 3-O-β-D-glucopyranoside (8), kaempferol 3-O-β-D-galactopyranoside (9), kaempferol 3-O-(2″,6″-di-O-E-p-coumaryl)-β-D-galactopyranoside (10), quercetin (11) and ellagic acid (12) were found in the ethyl acetate fraction. The structures of these compounds were determined by chemical and spectral analyses. Compounds 1-4, the flavonols (6 and 11) and ellagic acid (12) were found to be active against some of the tested microorganisms, while the kaempferol 3-O-glycosides (7-9) did not show any activity, indicating the role of the free 3-OH for antibacterial activity. Addition of p-coumaryl groups results in mild activity for 10 against Staphylococcus aureus and Bacillus cereus. Compounds 2-5, 7 and 9-12 are reported for the first time from M. malabathricum. Compound 10 is rare, being reported only once before from a plant, without assignment of the double bond geometry in the p-coumaryl moiety.     

The inhibitory potential of Thai mango seed kernel extract against methicillin-resistant Staphylococcus aureus

Plant extracts are a valuable source of novel antibacterial compounds to combat pathogenic isolates of methicillin-resistant Staphylococcus aureus (MRSA), a global nosocomial infection. In this study, the alcoholic extract from Thai mango (Mangifera indica L. cv. 'Fahlun') seed kernel extract (MSKE) and its phenolic principles (gallic acid, methyl gallate and pentagalloylglucopyranose) demonstrated potent in vitro antibacterial activity against Staphylococcus aureus and 19 clinical MRSA isolates in studies of disc diffusion, broth microdilution and time-kill assays. Electron microscopy studies using scanning electron microscopy and transmission electron microscopy revealed impaired cell division and ultra-structural changes in bacterial cell morphology, including the thickening of cell walls, of microorganisms treated with MSKE; these damaging effects were increased with increasing concentrations of MSKE. MSKE and its phenolic principles enhanced and intensified the antibacterial activity of penicillin G against 19 clinical MRSA isolates by lowering the minimum inhibitory concentration by at least 5-fold. The major phenolic principle, pentagalloylglucopyranose, was demonstrated to be the major contributor to the antibacterial activity of MSKE. These results suggest that MSKE may potentially be useful as an alternative therapeutic agent or an adjunctive therapy along with penicillin G in the treatment of MRSA infections.     

Antibacterial effect of five Zingiberaceae essential oils

Essential oil obtained by hydrodistillation and two different solvent extractions (petroleum ether and ethanol) from five Zingiberaceae species: ginger (Zingiber officinale Roscoe.), galanga (Alpinia galanga Sw.), turmeric (Curcuma longa L.), kaempferia (Boesenbergia pandurata Holtt.) and bastard cardamom (Amomum xanthioides Wall.) was characterized. Volatile components of all extracts were analyzed by gas chromatography-mass spectrometry (GC-MS). The major components of ginger, turmeric, galangal, bastard cardamom and kaempferia were zingiberene, turmerone, methyl chavicol, and gamma-terpinene, respectively. Their antibacterial effects towards Escherichia coli, Staphylococcus aureus, Bacillus cereus and Listeria monocytogenes were tested by a disc diffusion assay. Essential oil of kaempferia and bastard cardamom obtained by hydrodistillation extraction could inhibit growth of all tested bacteria. Essential oil of ginger extracted by hydrodistillation had the highest efficiency against three positive strains of bacteria (S. aureus, B. cereus and L. monocytogenes), with a minimum concentration to inhibit B. cereus and L. monocytogenes of 6.25 mg/mL.     

The synthesis and biological evaluation of a series of novel 2-COOC_2H_5/COONa substituted 1,5-benzothiazepine derivatives as antimicrobial agents

A series of novel 1,5-benzothiazepine derivatives containing COOC2H5/COONa groups at the C(2)-position were synthesized and evaluated for their antifungal and antibacterial activities by both disc diffusion and minimal inhibition concentration (MIC) methods. Most of the compounds have been shown to have moderate to good antibacterial activity against S. aureus, S. epidermidis and excellent antifungal activity against C. albicans.     

新型吡唑Schiff碱及金属配合物的合成和抑菌活性

以3-氨基-4-氰基吡唑和芳醛为原料合成了10个新型吡唑Schiff碱及铜(II)、镍(II)、锌(II)、钴(II) 4个金属配合物. 用元素分析, IR, 1H NMR及单晶解析表征了Schiff碱及金属配合物的结构. 测定了Schiff碱及金属配合物对金黄色葡萄球菌、大肠杆菌、枯草杆菌和绿脓杆菌的抑菌活性. 生物活性研究表明, Schiff碱及金属配合物对金黄色葡萄球菌、大肠杆菌和绿脓杆菌都有较好的抑菌效果, 其中铜(II)和锌(II)配合物对金黄色葡萄球菌和大肠杆菌的抑菌活性最好.     

Phytochemical and biological studies on Saudi Commiphora opobalsamum L

The aerial part of Commiphora opobalsamum L. (Burseraceae) growing in Saudi Arabia was subjected to a phytopharmacological investigation in order to identify its major chemical constituents and to evaluate its extracts and isolated compounds in preliminary in vitro assays for antimicrobial, antimalarial, antitumor, anti-inflammatory (COX-2 inhibition), antioxidant and estrogenic activity. Six compounds were isolated and identified as the triterpenes friedelin, canophyllal, and oleanonic acid; the flavonols mearnsetin and quercetin; and syringic acid. The ethyl acetate extract was moderately active against Staphylococcus aureus, Pseudomonas aeruginosa, and Plasmodium falciparum; while the petroleum ether and chloroform extracts inhibited COX-2 at 5 and 10 microg mL(-1), respectively. Of the isolated compounds, syringic acid showed moderate antimalarial, anticandidal, and antimycobacterial activity; while mearnsetin and quercetin exhibited antioxidant activity comparable to ascorbic acid and trolox. This is the first detailed phytochemical investigation of C. opobalsamum L. growing in Saudi Arabia and elsewhere. The isolated compounds are reported from this plant for the first time and their full (1)H and (13)C NMR assignments are included.     

Phytochemical analysis and antimicrobial activities of methanolic extracts of leaf, stem and root from different varieties of Labisa pumila Benth

A local herb, Kacip Fatimah, is famous amongst Malay women for its uses in parturition; however, its phytochemical contents have not been fully documented. Therefore, a study was performed to evaluate the phenolics, flavonoids, and total saponin contents, and antibacterial and antifungal properties of the leaf, stem and root of three varieties of Labisia pumila Benth. Total saponins were found to be higher in the leaves of all three varieties, compared to the roots and stems. Leaves of var. pumila exhibited significantly higher total saponin content than var. alata and lanceolata, with values of 56.4, 43.6 and 42.3 mg diosgenin equivalent/g dry weight, respectively. HPLC analyses of phenolics and flavonoids in all three varieties revealed the presence of gallic acid, caffeic acid, rutin, and myricetin in all plant parts. Higher levels of flavonoids (rutin, quercitin, kaempferol) were observed in var. pumila compared with alata and lanceolata, whereas higher accumulation of phenolics (gallic acid, pyrogallol) was recorded in var. alata, followed by pumila and lanceolata. Antibacterial activities of leaf, stem and root extracts of all varieties determined against both Gram positive (Micrococcus luteus, Bacillus subtilis B145, Bacillus cereus B43, Staphylococcus aureus S1431) and Gram negative (Enterobacter aerogenes, Klebsiella pneumonia K36, Escherichia coli E256, Pseudomonas aeruginosa PI96) pathogens showed that crude methanolic extracts are active against these bacteria at low concentrations, albeit with lower antibacterial activity compared to kanamycin used as the control. Antifungal activity of methanolic extracts of all plant parts against Fusarium sp., Candida sp. and Mucor using the agar diffusion disc exhibited moderate to appreciable antifungal activities compared to streptomycin used as positive control.     

Antibacterial evaluation of some Schiff bases derived from 2-acetylpyridine and their metal complexes

A series of Schiff bases derived from 2-acetylpyridne and their metal complexes were characterized by elemental analysis, NMR, FT-IR and UV-Vis spectral studies. The complexes were screened for anti-bacterial activity against Methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumanni (AC), Klebsiella pneumonie (KB) and Pseudomonas aeruginosa (PA) using the disc diffusion and micro broth dilution assays. Based on the overall results, the complexes showed the highest activities against MRSA while a weak antibacterial activity was observed against A. baumanii and P. aeruginosa.     

Antimicrobial and antioxidant phytochemicals in leaf extracts of Bergenia ligulata: a Himalayan herb of medicinal value

Phenolic and flavonoid contents in leaf extracts of Bergenialigulata have been analysed for their contribution in antimicrobial and antioxidant activities. The extracts were prepared in three solvents (separately) following maceration and soxhelt methods. The antimicrobial activity was tested using disc diffusion assay against a range of microorganisms along with the determination of minimum inhibitory concentration (MIC), while the antioxidant activity was tested following DPPH assay. Leaf extracts exhibited antimicrobial activity against all the three groups of microorganisms; results coincided with respective MIC. In general, the methanol extracts prepared through maceration favoured the determination of antimicrobial and antioxidant activities. Maximum values for phenolic and flavonoid contents were obtained in macerated methanol and ethyl acetate extracts, respectively. The statistical correlations exhibited the extent of the contribution of phenolic and flavonoid contents in antimicrobial and antioxidant activities and also indicated the involvement of other plant metabolites.     

Acute toxicity evaluation, antibacterial, antioxidant and immunomodulatory effects of Melastoma malabathricum

Melastoma malabathricum (MM) is a well-known plant in Malaysian traditional medicine, locally known as senduduk. Its ethanol and aqueous extracts have been used in the present investigation to study the immunomodulatory role on human peripheral blood mononuclear cell (PBMC), and the DPPH, ABTS and FRAP free radical scavenging activities were also measured. Total flavonoids and total phenolic contents were assayed and the antibacterial effect was tested against four species of bacteria; two Gram-positive (Staphylococcus aureus and Streptococcus agalactiae) and two Gram-negative (Escherichia coli and Klebsilla pneumonia). The tests were carried out using the disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. Moreover, the acute toxicity was evaluated in vivo on the ethanol extract of MM to establish its safety when administered orally. In our results, both extracts of MM showed abilities to scavenge DPPH and ABTS free radicals, IC(50) values: (11.599 ± 0.84, 10.573 ± 0.58 μmol/L) and (62.657 ± 0.78, 63.939 ± 0.48 μmol/L) for ethanol and aqueous extracts respectively. Indeed the ethanol extract evidenced high phenolic content (384.33 ± 0.005 mg/g), flavonoids contents (85.8 ± 0.009 mg/g) and ferric reducing antioxidant power (33,590 ± 0.038 mmol/g), with high activity against S. aureus and S. agalactiae (11 ± 0.3 and 12 ± 0.6 mm inhibition zones). Likewise, the percentage of peripheral blood mononuclear cells (PBMC) viability was increased in response to MM, IC(50) values (1.781 ± 1.2 and 6.545 ± 0.93 μg/mL) for ethanol and aqueous extracts, respectively. In addition, our results showed that the MM extract is safe even at a high dose of 5,000 mg/kg and has no oral toxicity. These findings suggest the excellent medicinal bioactivity of MM and explain the popularity of this plant in the folk medicine as a remedy for different illnesses.