Antimicrobial activity of coupled hydroxyanthracenones isolated from plants of the genus Karwinskia

The in vitro activity of some isolated hydroxyanthracenones belonging to the genus Karwinskia against four bacteria, six filamentous fungi and four yeast are reported. These hydroxyanthracenones were found to possess antimicrobial activity, particularly against Streptococcus pyogenes, Candida albicans, C. boidinii, C. glabrata and Cryptococcus neoformans; minimal inhibitory concentrations range between 16 and 2 microg/ml.     

Bioactive flavonoids from Kaempferia parviflora

Nine flavonoids (1-9) have been isolated from Kaempferia parviflora. Among these, 5,7,4'-trimethoxyflavone (8) and 5,7,3',4'-tetramethoxyflavone (9) exhibited antiplasmodial activity against Plasmodium falciparum, with IC50 values of 3.70 and 4.06 microg/ml, respectively. 3,5,7,4'-Tetramethoxyflavone (7) and compound 8 possessed antifungal activity against Candida albicans with respective IC50 values of 39.71 and 17.63 microg/ml, and also showed mild antimycobacterial activity with the minimum inhibitory concentrations (MIC) of 200 and 50 microg/ml, respectively. However, none of the isolated compounds demonstrated cytotoxicity against KB, BC and NCI-H187 cell lines.     

Antimicrobial activity of Diospyros anisandra

Leaves, root and stem bark of Diospyros anisandra were screened against two strains of Mycobacterium tuberculosis, one resistant and one susceptible to antibiotics, using the microplate Alamar blue assay test. The lypophylic fractions of the root and bark showed significant inhibitory activity against both strains, with the hexane fraction of the bark showing the strongest activity (MIC 6.25 microg/ml) against the resistant strain and a significant antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Candida albicans, Aspergillus niger, and Colletotrichum gloeosporioides. The bioassay-guided purification of the bioactive hexane fraction resulted in the isolation and identification of the naphthoquinone plumbagin as one of the metabolites responsible for the biological activity.     

Investigation of in vitro anthelmintic activities of Pycnanthus angolensis and Sphenocentrum jollyanum

Extracts from Pycnanthus angolensis stem bark, and fruits and seeds of Sphenocentrum jollyanum, when tested in vitro, showed potent anthelmintic activity on the earthworm, Eudrilus eugeniae. Methanolic extract of P. angolensis was more active than its chloroform extract (P<0.001), while fruit ethanolic extract of S. jollyanum was also more potent than the seed extract. When compared with other worms, S. jollyanum fruit extract showed the greatest activity on wireworms when tested at 80 mg/ml.     

In vitro antifungal activities of Allium cepa, Allium sativum and ketoconazole against some pathogenic yeasts and dermatophytes

By using an agar dilution assay, the antifungal activity of aqueous extracts prepared from Allium cepa (onion; AOE) and Allium sativum (garlic; AGE) were evaluated against Malassezia furfur (25 strains), Candida albicans (18 strains), other Candida sp. (12 strains) as well as 35 strains of various dermatophyte species and compared with the activity of a known antifungal drug, ketoconazole (KTZ). All the AOE, AGE and KTZ were found to be able to inhibit growth of all fungi tested in a dose-dependent manner with maximum of 100% at defined concentrations. The results indicate that onion and garlic might be promising in treatment of fungal-associated diseases from important pathogenic genera Candida, Malassezia and the dermatophytes.     

Compositions and antifungal activities of essential oils of some Algerian aromatic plants

Essential oils extracted from ten Algerian plants were analyzed for their potential activity against Candida albicans. The highest efficiency was obtained with the essential oil from Thymus numidicus which showed antifungal effect 1357 fold stronger than that measured with amphotericin B.     

Antimicrobial activity of crude methanolic extract of Satureja khuzistanica

The methanolic extract of the aerial parts of Satureja khuzistanica was investigated for its antimicrobial activity. The maximum antibacterial and antifungal activities were observed against Staphylococcus aureus and Candida albicans.     

Activity of Berberis aetnensis root extracts on Candida strains

The antifungal activity of methanolic extract and alkaloidal fraction of Berberis aetnensis against Candida species was investigated. The crude extract was active against Candida species, this activity being higher than that of the alkaloidal fraction and berberine.     

Phytochemical and antimicrobial investigations of stilbenoids and flavonoids isolated from three species of Combretaceae

The antimicrobial activity and chemistry of the African Combretaceae has been well studied in recent years. The present study aimed to investigate the phytochemistry and antimicrobial activity of lesser known members of this family viz. C. hereroense, C. apiculatum and C. collinum. Pulverized leaves of C. collinum and C. apiculatum, and the fruit of C. hereroense were extracted with organic solvents and subjected to preparative chromatography. Seventeen phenolic constituents including four phenanthrenes from the fruit of C. hereroense and two known bibenzyls (including a combretastatin) from the leaves of C. collinum were isolated. The compounds were then subsequently tested for their antimicrobial activity against Candida albicans, Mycobacterium fortuitum, Staphylococcus aureus, Escherichia coli and Proteus vulgaris. Pinocembrin showed excellent activity against C. albicans (MIC - 6.25 μg/ml), superior to that of the positive control, fluconazole and against S. aureus (MIC - 12.5 mg/ml). The phenanthrenes (compounds 1, 2, 3 and 5) showed some activity against M. fortuitum and S. aureus with a uniform MIC of 25 μg/ml. From this study it was evident that most stilbenoids and flavonoids from the selected Combretaceae have little or no antimicrobial activity.     

Antifungal activity of Agapanthus africanus extractives

The ethanolic extract of the rhizomes of Agapanthus africanus showed antifungal activity. In bioassay guided fractionation, n-butanol fraction exhibited significant activity against human pathogens. A saponin, (25R)-spirost-7-en-2alpha,3beta,5alpha-triol-3-O-[alpha-L-rhamnopyranosyl(1-->2)-[beta-D-galactopyranosyl (1-->3)] beta-D-glucopyranoside (1), responsible for the antifungal activity and having MIC value of 15.6 microg/ml against Trychophyton mentagrophytes and Sporothrix schenekii, was isolated and identified as active constituent of the plant.     

Anti-acne activity of tannin-related compounds isolated from Terminalia laxiflora

In our investigation to find out new anti-acne agent, we focused on Terminalia laxiflora Engl & Diels (Combretaceae) methanolic wood extract, which has been selected during previous screening experiments for anti-acne agents, which included 29 species of Sudanese medicinal plants. Based on the biologically guided fractionation using an antibacterial assay against Propionibacterium acnes, a lipase inhibitory assay and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity assay; five tannin-related compounds were isolated, such as ellagic acid, flavogallonic acid dilactone, terchebulin and gallic acid. Terchebulin showed good antibacterial activity; minimum inhibitory concentration (MIC) = 125 μg/ml and minimum bactericidal concentration (MBC) = 250 μg/ml. Gallic acid exhibited lipase inhibitory activity with IC₅₀ value of 149.3 μM, which showed strong inhibition compared with terchebulin, IC₅₀ 260.7 μM. However, all compounds exhibited better or equal DPPH radical scavenging activity to (+)-catechin as positive control. Ellagic acid and terchebulin showed the best DPPH radical scavenging activities, IC₅₀ 4.86 and 4.90 μM, respectively. This study demonstrated that terchebulin has potentiality as an anti-acne agent.     

Ent-trachyloban-19-oic acid isolated from Iostephane heterophylla as a promising antibacterial agent against Streptococcus mutans biofilms

From the roots of Iostephane heterophylla, six known compounds, namely, ent-trachyloban-19-oic acid (1), the mixture of ent-kaur-16-en-19-oic acid (2) and ent-beyer-15-en-19-oic acid (3), xanthorrhizol (4), 16α-hydroxy-ent-kaurane (5) and 16α-hydroxy-ent-kaur-11-en-19-oic acid (6) were isolated using a bioassay-guided fractionation method. The known compounds (1-6) were identified by comparison of their spectroscopic data with reported values in the literature. In an attempt to increase the resultant antimicrobial activity of 1 and 4, a series of reactions was performed on ent-trachyloban-19-oic acid (1) and xanthorrhizol (4), to obtain derivatives 1a, 1b, and 4a-4d. All the isolated compounds (1-6) and the derivatives 1a, 1b, and 4a-4d were evaluated for their antimicrobial activity against two oral pathogens, Streptococcus mutans and Porphyromonas gingivalis associated with caries and periodontal disease, respectively. Compounds 1, 1b, 2+3, 4 and 4d inhibited the growth of S. mutans with concentrations ranging from 4.1 μg/mL to 70.5 μg/mL. No significant activity was found on P. gingivalis except for 4 with an MIC of 6.8 μg/mL. The ability of 1, 1b, 2+3, 4 and 4d to inhibit biofilm formation by S. mutans was evaluated. It was found that 1, 1b, 4 and 4d interfered with the establishment of S. mutans biofilms, inhibiting their development at 32.5, 125.0, 14.1 and 24.4 μg/mL, respectively.     

COX-2 and sPLA2 inhibitory activity of aqueous extract and polyphenols of Rhizophora mangle (red mangrove)

The aqueous extract of Rhizophora mangle bark and its polyphenolic fractions showed remarkable in vitro antiinflammatory activity in a preliminary study. The low molecular weight fraction exhibited cyclooxygenase-2 inhibitory activity while the total aqueous extract and the low molecular weight fraction showed secretory phospholipase A(2) inhibitory activity.     

Triterpenoids of Euphorbia kansuensis Proch

Phytochemical investigation of the ethanol extract of Euphorbia kansuensis Proch. led to the isolation of three new triterpenoids, along with ten known compounds. Their structures were established by extensive 1D and 2D NMR, as well as other spectrum analysis. Biological activities of the three new compounds against Hela cell, Hep-G2 cell, C. albicans ATCC10231 cell and SC5314 cell were evaluated. They showed strong anti-tumor and moderate anti-inflammatory activities with MIC values ranging from 13 to 25μg/ml and from 30 to 128μg/ml.     

Antibacterial carbazole alkaloids from Clausena harmandiana twigs

Three new carbazole alkaloids, harmandianamines A-C (1-3), together with fifteen known compounds (4-18) were isolated from the twigs of Clausena harmandiana. The structures were elucidated by spectroscopic methods, including UV, IR, NMR, and MS. The antibacterial activity against Escherichia coli TISTR 780, Salmonella typhimurium TISTR 292, Staphylococcus aureus TISTR 1466 and methicillin-resistant S. aureus (MRSA) SK1 of some isolated compounds was also evaluated. Compound 6 exhibited significant antibacterial activity against MRSA SK1 with an MIC value of 0.25 μg/mL which higher than that of standard drug, vancomycin (MIC value=1 μg/mL) whereas compounds 14 and 5 showed strong activity with MIC values of 4 and 8 μg/mL, respectively. Only compound 14 showed strong antibacterial activity against S. aureus TISTR 1466 with an MIC value of 4 μg/mL.     

A new antifungal coumarin from Clausena excavata

A new γ-lactone coumarin, named as excavarin-A, showing antifungal activity was isolated from the leaves of Clausena excavata by bioassay guided fractionation method. The structure was elucidated by spectroscopic data analysis and identified as 7((2E)-4(4,5-dihydro-3-methylene-2-oxo-5-furanyl)-3-methylbut-2-enyloxy) coumarin. Minimum inhibitory concentration (MIC) was determined against fifteen fungal strains pathogenic against plants and human. The least MIC was recorded against the human pathogen, Candida tropicalis and the plant pathogens Rhizoctonia solani and Sclerotinia sclerotiorum. Antifungal activities against the human pathogens, Aspergillus fumigatus and Mucor circinelloides and plant pathogens, Colletotrichum gloeosporioides, Lasiodiplodia theobromae, Fusarium oxysporum and Rhizopus stolonifer were stronger than that of the standard antimicrobials.     

Antimicrobial and free radical scavenging activity of Gentianella nitida

The antimicrobial and free radical scavenging activity of the ethanol extract and fractions of Gentianella nitida have been assessed. The most susceptible microorganisms were Candida albicans, Trichophyton mentagrophytes and Microsporum gypseum. The antifungal activity was concentrated in the 90% methanol and nonsoluble fractions, while the radical scavenging activity was stronger in the ethyl acetate and nonsoluble fractions.     

Inhibition of clotrimazole-resistant Candida albicans by some endemic Sideritis species from Turkey

The anticandidal activity of the methanol extracts of seven endemic Sideritis species were evaluated at 30 mg/ml concentration against clotrimazole-resistant Candida albicans.     

Radical scavenging activity and composition of raspberry (Rubus idaeus) leaves from different locations in Lithuania

Raspberry (Rubus idaeus) leaves, collected in different locations of Lithuania were extracted with ethanol and the extracts were tested for their antioxidant activity (AA) by using ABTS(.)(+) decolourisation and DPPH(.) scavenging methods. All extracts were active, with radical scavenging capacity at the used concentrations from 20.5 to 82.5% in DPPH(.) reaction system and from 8.0 to 42.7% in ABTS(.)(+) reaction. The total amount of phenolic compounds in the leaves varied from 4.8 to 12.0 mg of gallic acid equivalents (GAE) in 1 g of plant extract. Quercetin glucuronide, quercetin-3-O-glucoside and rutin were identified in the extracts.     

Antibacterial activity of tannin constituents from Phaseolus vulgaris, Fagoypyrum esculentum, Corylus avellana and Juglans nigra

Tannins were fractionated from acetonic extract preparations of phenolic compounds from Phaseolus vulgaris, Fagoypyrum esculentum, Corylus avellana and Juglans nigra. Wide variations in antibacterial activities ranging from MICs of 62.5 to 500 microg/ml were apparent. Of particular note was a relatively high level of activity (62.5 to 125 microg/ml) for all extracts against Listeria monocytogenes.