Antimicrobial activity of the methanolic extracts and compounds from Treculia obovoidea (Moraceae)

The crude extract from Treculia obovoidea was subjected to purification by repeated chromatography. Eight compounds were isolated from Treculia obovoidea and identified as Psoralen (1), Bergapten (2), 7-methoxycoumarin (3), 7-hydroxycoumarin (4), 4,2′,4′-trihydroxychalcone (5), 4,2′,4′-trihydroxy-3-prenylchalcone (6), 3-hydroxy-4-methoxybenzoic acid (7) and O-[3-(2,2-dimethyl-3-oxo-2H-furan-5-yl) butyl] bergaptol (8). These compounds together with the extract were tested for their antimicrobial activity against Gram-positive bacteria (six species), Gram-negative bacteria (12 species) and three Candida species using micro-dilution methods for the determination of the minimal inhibition concentration (MIC) and the minimal microbicidal concentration (MMC). The MIC values obtained with the crude extracts varied from 78.12 to 156.25 μg/ml against 17 (80.95%) of the 21 tested microorganisms. All the isolated compounds showed selective activity. The antimicrobial activity of this plant as well as that of compounds 6 and 8 is being reported for the first time. The obtained results provide promising baseline information for the potential use of these crude extract as well as some of the isolated compounds in the treatment of bacterial and fungal infections.     

Antimicrobial activity of Acacia mellifera extracts and lupane triterpenes

Ethnopharmacological relevance

Acacia mellifera (Vahl) Benth (Leguminosae) is a subtropical medicinal plant that is widely used in traditional African medicines against various diseases such as pneumonia and malaria.

Aim of the study

The present study was performed to evaluate the antimicrobial effects of extracts from the stem bark of Acacia mellifera.

Materials and methods

The extracts were examined for antibacterial and antifungal activity using the disc-diffusion method against bacterial strains: Streptococcus pneumoniae (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 35218), Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923) and fungal strains Candida albicans (ATCC 90028), Candida krusei (ATCC 6255), Cryptococcus neoformans (ATCC 6603) and clinical isolates of Microsporum gypseum and Trichophyton mentagrophytes.

Results

Some of these extracts were found to be active against some bacterial and fungal strains and were further fractionated to give 12 pure compounds. The methanolic and methanol:dichloromethane (1:1) extracts exhibited antibacterial and antifungal activity. The two were active against Staphylococcus aureus (ATCC 25923), Microsporum gypseum, and Trichophyton mentagrophytes. Activity guided fractionation led to isolation of two active compounds: 3-(Z)-cis coumaroylbetulin and 30-hydroxylup-20 (29)-en-3β-ol which were against Staphylococcus aureus (ATCC 25923), Microsporum gypseum, Trichophyton mentagrophytes and Pseudomonas aeruginosa (ATCC 27853).

Conclusions

These results may partly explain and support the use of Acacia mellifera stem barks for the treatment of infectious diseases in traditional Kenya medicine.     

Antimicrobial activity of Schinus lentiscifolius (Anacardiaceae)

Ethnopharmacological relevance

Schinus lentiscifolius Marchand (syn. Schinus weinmannifolius Engl) is a plant native to Rio Grande do Sul (Southern Brazil) and has been used in Brazilian traditional medicine as antiseptic and antimicrobial for the treatment of many different health problems as well as to treat leucorrhea and to assist in ulcer and wound healing. Although it is a plant widely used by the population, there are no studies proving this popular use.

Material and methods

The crude aqueous extract, the crude neutral methanol extract, fractions prepared from this extract (n-hexane, ethyl acetate, and n-butanol), pure compounds isolated from these fractions, and derivatives were investigated in vitro for antimicrobial activities against five Gram positive bacteria: Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Streptococcus pyogenes, three Gram negative bacteria: Escherichia coli, Pseudomonas aeruginosa, and Shigella sonnei, and four yeasts: Candida albicans, Candida tropicalis, Cryptococcus neoformans, and Saccharomyces cerevisiae. The isolated compound moronic acid, which is the most active, was tested against a range of other bacteria such as two Gram positive bacteria, namely, Bacillus cereus, Enterococcus spp, and six Gram negative bacteria, namely, Burkholderia cepacia, Providencia stuartii, Morganella morganii, Enterobacter cloacae, Enterobacter aerogenes, and Proteus mirabilis.

Results

The leaf aqueous extract (decoction) of Schinus lentiscifolius showed a broad spectrum of antibacterial activity, ranging from 125 to 250 μg/ml (MIC) against the tested bacteria and fungi. The n-hexane extract, despite being very little active against bacteria, showed an excellent antifungal activity, especially against Candida albicans (MIC=25 μg/ml), Candida tropicalis (MIC=15.5 μg/ml), and Cryptococcus neoformans, (MIC=15.5 μg/ml). From the acetate fraction (the most active against bacteria), compounds 1–6 were isolated: nonadecanol (1), moronic acid (2), gallic acid methyl ester (3), gallic acid (4), quercetin (5) and quercitrin (6). The minimal inhibitory concentration (MIC) of moronic acid between 1.5 and 3 μg/ml against most of the tested bacteria shows that it is one of the metabolites responsible for the antibacterial activity of Schinus lentiscifolius.

Conclusion

The antimicrobial activity and some constituents of Schinus lentiscifolius are reported for the first time. The results of the present study provide scientific basis for the popular use of Schinus lentiscifolius for a number of different health problems.     

Antimicrobial activity of the crude extract,fractions and compounds from stem bark of Ficus ovata (Moraceae)

Aim of the study

This study was designed to investigate the antimicrobial activities of the methanol extracts from the stem bark of Ficus ovata (FOB), fractions (FOB1–6) and compounds isolated following bio-guided fractionation [3-friedelanone (1), taraxeryl acetate (2), betulinic acid (3), oleanoïc acid (4), 2-hydroxyisoprunetin (5), 6,7-(2-isopropenyl furo)-5,2,4-trihydroxyisoflavone (6), Cajanin (7) and protocatechuic acid (8)].

Materials and Methods

The micro-dilution method was used for the determination of the minimal inhibition concentration (MIC) and the minimal microbicidal concentration (MMC) against fungi (two species), Gram-positive (three species) and Gram-negative bacteria (five species).

Results

The results of the MIC determinations indicated that the crude extract (FOB), fractions FOB2 and FOB4 as well as compound 5 were active on the entire studied organisms. Other samples showed selective activity, fractions FOB1, FOB3 and FOB5 being active against 50% of the tested microbial species while FOB6 was active on 40%. Compounds 8, 6, 2 and 7 prevented the growth of 80%, 70%, 50% and 20% of the organisms respectively. The lowest MIC value (156g/ml) observed with the crude extract was recorded on Streptococcus faecalis, Candida albicans and Microsporum audouinii. The corresponding value for fractions (39 μg/ml) was noted with FOB4 against Staphylococcus aureus, while that of the tested compounds (10 μg/ml) was observed with compound 8 on Microsporum audouinii. The results of the MMC determination suggested that the cidal effect of most of the tested samples on the studied microorganisms could be expected.

Conclusions

The overall results provided evidence that the studied plant extract, as well as some of the isolated compounds might be potential sources of new antimicrobial drug.     

Antimicrobial activity of the methanolic extracts and compounds from Vismia laurentii De Wild (Guttiferae)

Methanolic extracts prepared from the leaves, twigs and the roots of Vismia laurentii De Wild as well as nine compounds isolated from these crude extracts, were tested for their antimicrobial activity against Gram-positive bacteria (six species), Gram-negative bacteria (12 species) and two Candida species using disc diffusion and well micro-dilution methods. The disc diffusion assay indicated that the crude extract was active against all the pathogens tested, whereas isolated compounds showed selective activities. The degree of sensitivity of the test organisms to purified compounds varied from 25 to 90%. Fridelin (8) was found to be the most active compound, while Bivismiaquinone (3) was the least active. The lowest minimum inhibition concentration (MIC) values as obtained by the micro-dilution assays were 19.53 and 1.22 microg/ml for the crude extracts and purified compounds, respectively. The lowest value for the purified compounds (1.22 microg/ml) was obtained with O(1)-demethyl-3',4'-deoxypsorospermin-3',4'-diol (6) on Candida gabrata and Bacillus subtilis; 1,8-dihydroxy-6-methoxy-3-methylanthraquinone (5) on Bacillus subtilis and 6-deoxyisojacareubin (7) on Bacillus stearothermophilus. These results provide promising baseline information for the potential use of these crude extracts as well as some of the isolated compounds in the treatment of bacterial and fungal infections.     

Anti-nociceptive activity of Pereskia bleo Kunth. (Cactaceae) leaves extracts

Ethnopharmacological relevance

Local communities in Malaysia consume Pereskia bleo Kunth. (Cactaceae) leaves as raw vegetables or as a concoction and drink as a tea to treat diabetes, hypertension, rheumatism, cancer-related diseases, inflammation, gastric pain, ulcers, and for revitalizing the body.

Aim of the study

To evaluate anti-nociceptive activity of the extracts and vitexin, isolated for the first time in this species, in two analgesic models; formalin-induced licking and acetic acid-induced abdominal writhing.

Materials and methods

Three and a half kilos of P. bleo leaves were extracted using Soxhlet apparatus with ethanol for 72 h. The crude ethanol extract was treated with activated charcoal overnight and subjected to a liquid–liquid partition yielding hexane, dichloromethane, ethyl acetate and butanol extracts. All extracts, including the crude ethanol and vitexin isolated from the ethyl acetate partition were tested for peripheral anti-nociceptive activity using formalin test and acetic acid-induced abdominal writhing, besides having their acute toxicity assays performed.

Results

The phytochemical analyses resulted in the isolation of vitexin (1), β-sitosterol glucoside (2) and β-sitosterol (3) isolated from the ethyl acetate, dichloromethane and hexane extracts, respectively. This is the first time vitexin and β-sitosterol glucoside are isolated from this species. The anti-nociceptive activities for all extracts were only moderate. Vitexin, which was isolated from the ethyl acetate extract did not show any activity in all models tested when used alone at the same concentration as it appears in the extract.

Conclusion

This study showed that all the extracts possess moderate anti-nociceptive activity. Vitexin is not the compound responsible for the anti-nociceptive effect in the ethyl acetate extract. Further investigations are needed to identify the compound(s) that might be responsible for the anti-nociceptive activity in this plant.     

Antimicrobial activity of the methanolic extract and compounds from Morus mesozygia stem bark

Aim of the study

This study was aimed at investigating the antimicrobial activity of the methanolic extract (MMB) and compounds isolated from the stem bark of Morus mesozygia, namely 3β-acetoxyurs-12-en-11-one (1), moracin Q (2), moracin T (3), artocarpesin (4), cycloartocarpesin (5), moracin R (6), moracin U (8), moracin C (9), and moracin M (10).

Materials and Methods

The liquid microdilution assay was used in the determination of the minimal inhibitory concentration (MIC) and the minimal microbicidal concentration (MMC), against nine bacterial and two fungal species.

Results

The results of the MIC determination showed that the compounds 3, 4, 8 and 9 were able to prevent the growth of all tested microbial species. All other samples showed selective activities. Their inhibitory effects were noted on 90.9% studied organisms for the crude extract, 81.8% for compound 6, 72.7% for compound 10, 63.6% for compound 1, 54.5% for compound 5, and 45.5% for compound 2. The lowest MIC value of 39 μg/ml was obtained with the crude extract against Escherichia coli. The corresponding value for compounds (5 μg/ml) was registered with compound 9 on Shigella dysenteriae and compound 3 on E. coli, S. dysenteriae, Pseudomonas aeruginosa, Salmonella typhi and Bacillus cereus. The lowest MIC value (39 μg/ml) observed with the crude extract (on E. coli) was only eightfold greater than that of gentamycin used as reference antibiotic (RA) while the corresponding value (5 μg/ml) recorded with compounds 3 and 9 was equal to that of RA on the corresponding microorganisms.

Conclusions

The obtained results highlighted the interesting antimicrobial potency of M. mesozygia as well as that of the studied compounds, and provided scientific basis for the traditional use of this species.     

In vitro antimicrobial activity of extracts and compounds of some selected medicinal plants from Cameroon

Aim of the study

Seven extracts and eight compounds from four selected Cameroonian medicinal plants, Solanecio mannii Hook f. (Asteraceae), Monodora myristica Dunal (Annonaceae), Albizia gummifera (J.F. Gmel) C.A. Smith (Fabaceae/Mimosoideae) and Glyphaea brevis (Spreng) Monachino (Tiliaceae), traditionally used for the treatment of hepatitis, parasites and other infectious diseases, were tested in vitro for their antimicrobial activity against Gram-positive (5 species) and Gram-negative (4 species) bacteria species and pathogenic yeasts (2 Candida species), to establish whether or not they have antimicrobial activity and to validate scientifically their use in traditional medicine.

Materials and methods

The agar disc diffusion and the microbroth dilution methods were used to determine the zone of inhibition between the edge of the filter paper and the edge of the inhibition area (IZ) and the minimal inhibitory concentration (MIC) respectively.

Results

The most active extracts against Candida albicans and Candida krusei were respectively the cyclohexane extract from the fruits of Monodora myristica and the ethyl acetate extract from the stem bark of Albizia gummifera (MIC = 6.3 μg/ml for both extracts). The lowest MIC value (1.6 μg/ml) for purified compounds was obtained on Candida albicans with a mixture of linear aliphatic primary alcohols (n-C24H50O to n-C30H62O), with n-hexacosanol (1b) as major compound and mixture of fatty acid esters of diunsaturated linear 1,2-diols (6).

Conclusion

These results afford ground informations for the potential use of the crude extracts of these species as well as of some of the isolated compounds in bacterial and fungal infections.     

Toxicity,antimicrobial and anthelmintic activities of Vernonia guineensis Benth. (Asteraceae) crude extracts

Ethnopharmacological relevance

This study examined the antibacterial, antifungal, and anthelmintic properties of extracts obtained from the plant Vernonia guineensis, a plant commonly used in traditional Cameroonian medicine.

Materials and methods

For in vitro studies, 10 g of leaf and tuber powder from V. guineensis was extracted separately using dichloromethane, methanol and distilled water. The extracts were dried in vacuo and used for antimicrobial and anthelmintic activity studies. In the antimicrobial assay, extracts were tested against bacterial and fungal organisms including; Staphylococcus aureus, Staphylococcus epidermidis, Acinetobacter baumannii, Aspergillus fumigatus, Candida albicans and Trichophyton mentagrophytes. In the anthelmintic assay, larval and adult stages of the hookworm Ancylostoma ceylanicum and the mouse nematode Trichuris muris were used. For the acute toxicity test, male and female rats of 150–200 g body weight were used in the experiment. The aqueous extract of V. guineensis tubers was administered in 4 doses of 500, 1000, 2000 and 4000 mg/kg per group (n=6), respectively, and the control group received distilled water.

Results

The crude extracts exhibited weak antibacterial and antifungal activity except for the dichloromethane extract, which showed moderate activity against A. fumigatus (MIC=200 μg/ml). In the anthelmintic assay, the organic extracts of the tubers had 100% killing efficacy against T. muris at 2 mg/ml in 48 h, while the aqueous extract showed no activity. The organic leaf extracts demonstrated potent activity killing 100% of the adult worms 1 mg/ml in 24 h. The aqueous leaf extract was active at 2 mg/ml in 72 h, killing 100% of the adult worms. In the acute toxicity test, V. guineensis did not produce any toxic signs or death at the maximum concentration of 4000 mg/kg.

Conclusion

Crude extracts from V. guineensis possess anthelmintic activity against T. muris with only weak antibiotic activity. Acute administration of aqueous extract from V. guineensis tubers did not produce toxic effects in rats. The absence of acute toxicity at the highest concentration tested indicates that the tea decoction from V. guineensis extract is safe at concentrations ≤4000 mg/kg.     

Antimicrobial activity of the essential oil and extracts of Cordia curassavica (Boraginaceae)

In traditional Mexican medicine Cordia curassavica (Jacq) Roemer & Schultes is used to treat gastrointestinal, respiratory and dermatological disorders in Zapotitlán de las Salinas, Puebla (México). The aim of this work was to investigate antimicrobial activity of the essential oil, obtained by using Clevenger distillation apparatus, and hexane, chloroform and methanol extracts from aerial parts of Cordia curassavica. Antimicrobial activity was evaluated against 13 bacteria and five fungal strains. The oil and extracts exhibited antimicrobial activity against Gram-positive and Gram-negative bacteria and five fungal strains. Sarcina lutea and Vibrio cholerae were the strains more sensitive to the essential oil effect (MIC=62 microg/mL) and Vibrio cholerae for the hexane extract (MIC=125 microg/mL). Rhyzoctonia solani was the strain more sensitive to the essential oil effect (IC(50)=180 microg/mL) and Trichophyton mentagrophytes for the hexane extract (IC(50)=230 microg/mL). The essential oil was examined by GC and GC-MS. A total 11 constituents representing 96.28% of the essential oil were identified: 4-methyl,4-ethenyl-3-(1-methyl ethenyl)-1-(1-methyl methanol)cyclohexane (37.34%), beta-eudesmol (19.21%), spathulenol (11.25%) and cadina 4(5), 10(14) diene (7.93%) were found to be the major components. The present study tends to confirm the use in the folk medicine of Cordia curassavica in gastrointestinal, respiratory and dermatological diseases.     

Antimicrobial activity of Ulopterol isolated from Toddalia asiatica (L.) Lam.: a traditional medicinal plant

Ethnopharmacological relevance

The leaves of Toddalia asiatica (L.) Lam. (Rutaceae) are widely used in folk medicine in India to treat various ailments like cough, malaria, indigestion, influenza lung diseases and rheumatism, fever, stomach ailments, cholera and diarrhea. In our earlier communication we have reported the antimicrobial study on the various extracts of the leaves and the isolation and identification of Flindersine, a quinolone alkaloid as the major active principle. In the present study, we report the antibacterial and antifungal activities of Ulopterol, a coumarin isolated as another major active antimicrobial principle.

Materials and methods

The leaves were successively extracted with hexane, chloroform, ethyl acetate, methanol and water. The extracts were studied for their antimicrobial activity against selected bacteria and fungi by using disc-diffusion method. The ethyl acetate extract which was found to possess highest antimicrobial activity was subjected to activity guided fractionation by column chromatography over silica gel. This resulted in the isolation of the coumarin, Ulopetrol, an active principle besides Flindersine which was reported by us earlier. The structure of the compound was elucidated using physical and spectroscopic data. Flindersine and Ulopterol were quantified by HPLC.

Results

Ulopterol showed activity against the bacteria viz. Staphylococcus epidermidis, Enterobacter aerogenes, Shigella flexneri, Klebsiella pneumoniae (ESBL-3967), Escherichia coli (ESBL-3984) and fungi viz. Aspergillus flavus, Candida krusei and Botrytis cinerea. Quantification by HPLC showed the content of Flindersine and Ulopterol to be 0.361% and 0.266% respectively on dry weight basis of the leaves.

Conclusions

Ethyl acetate extract (successive extraction) contained Ulopterol, a coumarin, besides Flindersine, a quinolone alkaloid, as a major active principle in the antimicrobial studies. This is the first report of the antimicrobial activity of Ulopterol and also its first report from the plant.     

Antitubercular activity of Arctium lappa and Tussilago farfara extracts and constituents

Ethnopharmacological relevance

Arctium lappa and Tussilago farfara (Asteraceae) are two plant species used traditionally as antitubercular remedies. The aim of this study was (i) to screen Arctium lappa and Tussilago farfara extracts for activity against Mycobacterium tuberculosis and (ii) to isolate and identify the compound(s) responsible for this reputed anti-TB effect.

Materials and methods

The activity of extracts and isolated compounds was determined against Mycobacterium tuberculosis H₃₇R_v using a high throughput spot culture growth inhibition (HT-SPOTi) assay.

Results

The n-hexane extracts of both plants, the ethyl acetate extract of Tussilago farfara and the dichloromethane phase derived from the methanol extract of Arctium lappa displayed antitubercular activity (MIC 62.5 μg/mL). Further chemical investigation of Arctium lappa led to the isolation of n-nonacosane (1), taraxasterol acetate (2), taraxasterol (3), a (1:1) mixture of β sitosterol/stigmasterol (4), isololiolide (5), melitensin (6), trans-caffeic acid (7), kaempferol (8), quercetin (9), kaempferol-3-O-glucoside (10). Compounds isolated from Tussilago farfara were identified as a (1:1) mixture of β sitosterol/stigmasterol (4), trans-caffeic acid (7), kaempferol (8), quercetin (9), kaempferol-3-O-glucoside (10), loliolide (11), a (4:1) mixture of p-coumaric acid/4-hydroxybenzoic acid (12), p-coumaric acid (13). All compounds were identified following analyses of their physicochemical and spectroscopic data (MS, ¹H and ¹³C-NMR) and by comparison with published data. This is the first report of the isolation of n-nonacosane (1), isololiolide (5), melitensin (6) and kaempferol-3-O-glucoside (10) from Arctium lappa, and of loliolide (11) from Tussilago farfara. Amongst the isolated compounds, the best activity was observed for p-coumaric acid (13) (MIC 31.3 μg/mL or 190.9 μM) alone and in mixture with 4-hydroxybenzoic acid (12) (MIC 62.5 μg/mL).

Conclusions

The above results provide for the first time some scientific evidence to support, to some extent, the ethno-medicinal use of Arctium lappa and Tussilago farfara as traditional antitubercular remedies.     

In vivo antimalarial activity of Keetia leucantha twigs extracts and in vitro antiplasmodial effect of their constituents

Ethnopharmacological relevance

The West African tree Keetia leucantha (Rubiaceae) is used in traditional medicine in Benin to treat malaria. The twigs dichloromethane extract was previously shown to inhibit in vitro Plasmodium falciparum growth with no cytotoxicity (>100 µg/ml on human normal fibroblasts).

Materials and methods

The dichloromethane and aqueous extracts of twigs of K. leucantha were evaluated in vivo against Plasmodium berghei NK 173 by the 4-day suppressive test and in vitro against a chloroquine-sensitive strain of Plasmodium falciparum (3D7) using the measurement of the plasmodial lactate dehydrogenase activity. Bioguided fractionations were realized and compounds were structurally elucidated using extensive spectroscopic analysis.

Results

The in vivo antimalarial activity of K. leucantha dichloromethane and aqueous twigs extracts were assessed in mice at the dose of 200 mg/kg/day. Both extracts exhibited significant effect in inhibiting parasite growth by 56.8% and 53.0% (p<0.0001) on day 7-postinfection. An LC–MS analysis and bioguided fractionations on the twigs dichloromethane extract led to the isolation and structural determination of scopoletin (1), stigmasterol (2), three phenolic compounds: vanillin (3), hydroxybenzaldehyde (4) and ferulaldehyde (5), eight triterpenic esters (6–13), oleanolic acid and ursolic acid. The antiplasmodial activity of the mixture of the eight triterpenic esters showed an antiplasmodial activity of 1.66±0.54 µg/ml on the 3D7 strain, and the same range of activity was observed for isolated isomers mixtures.

Conclusions

This is the first report on the in vivo activity of K. leucantha extracts, the isolation of thirteen compounds and analysis of their antiplasmodial activity. The results obtained may partially justify the traditional use of K. leucantha to treat malaria in Benin.     

Antimicrobial activity of the methanolic extract, fractions and four flavonoids from the twigs of Dorstenia angusticornis Engl. (Moraceae)

The methanolic extract (DAT), fractions (FRS) and four flavonoids, namely Gancaonin Q (1), Stipulin (2), Angusticornin B (3) and Bartericin A (4), isolated from the twigs of Dorstenia angusticornis (Moraceae), were tested for their in vitro antimicrobial activity. A total of 22 microbial cultures belonging to three Candida species, 6 Gram-positive and 13 Gram-negative bacterial species were used in this study. The inhibition zones (IZ) of the test samples against the pathogens were determined by the Agar Hole Diffusion test while the Liquid dilution method was used to determine their minimal inhibition concentrations (MIC) and their minimal microbicidal concentrations (MMC). Results indicate that DAT, compounds 3 and 4 inhibited the growth of all test pathogens. DAT, FRS 3-6, compounds 3 and 4 were both antibacterial and anticandidal. A single-dose oral toxicity performed in accordance with the OPPTS 870.1100 and OECD 401guideline showed that DAT was not toxic. Our findings provide a possible basis for the potential use of twigs from Dorstenia angusticornis in the treatment of infectious diseases.     

Antimicrobial compounds from Alpinia conchigera

Ethnopharmacological relevance

The rhizome of Alpinia conchigerahas been used as a condiment in the northern states of Peninsular Malaysia and occasionally in folk medicine in the east coast to treat fungal infections. In some states of Peninsular Malaysia, the rhizomes are consumed as a post-partum medicine and the young shoots are prepared into a vegetable dish. This study aimed to investigate the chemical constituents of the pseudostems and rhizomes of Malaysian Alpinia conchigera and to evaluate the antimicrobial activity of the dichloromethane (DCM) extracts of the pseudostems, rhizomes and the isolated compounds against three selected fungi and five strains of Staphylococcus aureus.

Materials and methods

The dried and ground pseudostems (0.8 kg) and rhizomes (1.0 kg) were successively extracted in Soxhlet extractor using n-hexane, dichloromethane (DCM) and methanol. The n-hexane and DCM extracts of the pseudostem and rhizome were subjected to isolation and purification using column chromatography on silica gel using a stepwise gradient system (n-hexane to methanol). Briefly, a serial two fold dilutions of the test materials dissolved in DMSO were prepared prior to addition of 100 μl overnight microbial suspension (108 cfu/ml) followed by incubation at 37 °C (bacteria) or 26 °C (dermatophytes and candida) for 24 h. The highest concentration of DMSO remaining after dilution (5%, v/v) caused no inhibition to bacterial/candida/dermatophytes’ growth. Antibiotic cycloheximide was used as reference for anticandidal and antidermatophyte comparison while oxacilin was used as reference for antibacterial testing. DMSO served as negative control. Turbidity was taken as indication of growth, thus the lowest concentration which remains clear after macroscopic evaluation was taken as the minimum inhibitory concentration (MIC).

Results

The isolation of n-hexane and DCM extracts of the rhizomes and pseudostems of Alpinia conchigera via column chromatography yielded two triterpenes isolated as a mixture of stigmasterol and β-sitosterol: caryophyllene oxide, chavicol acetate 1, p-hydroxy cinnamaldehyde 2, 1′S-1′-acetoxychavicol acetate 3, trans-p-coumaryl diacetate 4, 1′S-1′-acetoxyeugenol acetate 5, 1′-hydroxychavicol acetate 6, p-hydroxycinnamyl acetate 7 and 4-hydroxybenzaldehyde.The DCM extract of the rhizome of Alpinia conchigera indicated potent antifungal activity against Candida albicans, Microsporum canis and Trycophyton rubrum with MIC values of 625 μg/ml, 156 μg/ml and 156 μg/ml, respectively. It also showed significant inhibitory activity with MIC values between 17.88 and 35.75 μg/ml against the mutant Staphylococci isolates MSSA, MRSA and Sa7.Amongst the isolated compounds, the lowest inhibition observed were of 1′S-1′-acetoxyeugenol against the dermatophytes (MIC 313 μg/ml) followed by trans-p-coumaryl diacetate against both dermatophytes and candida (MIC 625 μg/ml). The compound p-hydroxycinnamyl acetate strongly inhibited Staphylococcusaureus strain VISA (MIC 39 μg/ml) followed by trans-p-coumaryl diacetate and 1′-hydroxychavicol acetate with MIC value of 156 μg/ml.

Conclusion

In conclusion, the observed antibacterial, anticandidal and antidermatophyte activity of the extracts and compounds obtained from the rhizome confirm the traditional use of Alpinia cochigera rhizome in the treatment of skin infection.     

苗药芭蕉体外抗菌活性研究

目的:研究芭蕉根和芭蕉花不同提取部位对金黄色葡萄球菌(SA)、耐甲氧西林的金黄色葡萄球菌(MRSA)和β-内酰胺酶阳性的金黄色葡萄球菌(ESBLs)的抑菌活性。方法:采用纸片扩散法测定不同提取部位的最低抑菌浓度(MIC)。结果:芭蕉根石油醚部位对SA,MRSA和ESBLs均有抑制作用,MIC全部为31.25μg·disc-1;芭蕉根正丁醇部位对MRSA,ESBLs有抑制作用,MIC都为250μg·disc-1;芭蕉花石油醚部位对SA、MRSA和ESBLs都有抑制作用,MIC均为125μg·disc-1。抑菌活性大小顺序为芭蕉根石油醚部位芭蕉花石油醚部位芭蕉根正丁醇部位。结论:芭蕉根和芭蕉花的石油醚部位是芭蕉的抑菌活性部位。     

Antimicrobial phenylpropanoids from the Argentinean highland plant Parastrephia lucida (Meyen) Cabrera

Ethnopharmacological relevance

The Argentinean highland plant Parastrephia lucida (Meyen) Cabrera is used in traditional medicine as an antiseptic and anti-inflammatory crude drug.

Aim of the study

To relate the antimicrobial effect of the crude drug with the constituents of the active fractions and traditional use.

Materials and methods

Assay-guided isolation of the methanol (MeOH) plant extract was carried out using bacteria and yeasts as target organisms. Both ATCC and local strains were included in the study. The antimicrobial fractions and compounds were detected by bioautographic assays. Minimum inhibitory concentrations (MIC) of each extract and fraction were determined and compared with reference antibiotics. Fractions were analyzed by HPLC–DAD, GC–MS, ¹H NMR and ¹³C NMR.

Results

From the MeOH extract of the plant, assay-guided isolation of the antimicrobial constituents led to 12 phenylpropanoids and two simple phenolics. Most of the compounds occurring in the active fractions were E-caffeoyl or E-cinnamoyl esters including prenyl and phenethyl derivatives. The MIC values of the most active fractions ranged between 12.5 and 200 μg/mL against reference strains and local isolates of Staphylococcus aureus and Enterococcus faecalis.

Conclusions

The antimicrobial effect found in the crude drug was associated with mixtures of phenylpropanoids, including prenyl and phenethyl esters of caffeic and cinnamic acids. The results support at least in part the traditional use of the plant as local antiseptic.     

In vitro estrogenic activity of Asplenium trichomanes L. extracts and isolated compounds

Ethnopharmacological relevance

Asplenium trichomanes was used as an expectorant, anti-cough remedy, laxative, emmenagogue, abortifacient and for irregular menses.

Aim of the study

To investigate the in vitro estrogenic activity of Asplenium trichomanes extracts and isolated compounds and their ability to activate ERα and ERβ.

Materials and methods

Leaves infusion (IF), decoction (DC) and methanol extract (ME) were prepared. MCF7/EREluc cell line which expresses endogenous ERα, and SK-NBE cells transiently transfected with the estrogen receptors (ERα and ERβ) were used for the estrogenic activity assays. Phytochemical investigations were performed (CC, HPLC, etc.) and structure of isolated compounds were achieved on the basis of 1D and 2D NMR techniques and HR-MS spectrometry.

Results

IF and ME were active in our MCF7 model; selectivity for the ERβ receptor was observed in the SK-NBE test. Two new phenol derivatives, 4-vinyl-phenol-1-O-[α-l-rhamno(1 → 6)-β-d-glucopyranosyde] (1) and kaempferol-3-O-α-[2′acetyl]-arabinofuranosyl-7-O-α-l-rhamnopyranoside (2) were isolated with six known compounds (3–8). Compounds 2–4, 7 and 8 showed selectivity for the activation of the ERβ receptor although with a moderate activity compared with 17-β-estradiol.

Conclusion

Further investigations about the estrogenic effects of this plant are needed but our data can, at least in part, explain some of its traditional use as emmeagogue.     

Essential oils of Salvia bracteata and Salvia rubifolia from Lebanon: Chemical composition,antimicrobial activity and inhibitory effect on human melanoma cells

Aim of the study

Salvia bracteata Banks et Sol. and Salvia rubifolia Boiss. are known in folk medicine of Lebanon for the treatment of microbial infections, cancer, urinary and pulmonary problems. In the present study the chemical composition and antimicrobial activity of essential oils from aerial parts of Salvia bracteata and Salvia rubifolia collected in Lebanon were evaluated. The oils were also tested for their potential antiproliferative effects against M14 human melanoma cells.

Material and methods

The oils were studied by GC and GC–MS and their antibacterial activity (MIC and MBC) was tested against ten bacteria species using the broth dilution method. The inhibitory effect on human melanoma cells (measurement of cell vitality, cell membrane integrity and genomic DNA fragmentation) was studied using MTT assay, calculation of LDH release and COMET assay.

Results

The oils showed a good antibacterial activity (MIC = 50 μg/ml) against Gram+ bacteria. They besides exhibited an inhibitory effect on the human cancer cells examined inducing also apoptotic cell death, but the oil of Salvia rubifolia was significantly (p < 0.001) more active as compared to the oil of Salvia bracteata.

Conclusion

The results on the pharmacological activities of these Salvia species provide an in vitro scientific support for the use of these plants in traditional herbal preparations.     

In-vitro and in-vivo antiadipogenic,hypolipidemic and antidiabetic activity of Diospyros melanoxylon (Roxb)

Ethnopharmacological relevance

The plant Diospyros melanoxylon (Roxb) belongs to the family Ebenaceae that is native to India and Sri-lanka. This is a medium-sized tree, reaching a height of 15 m and is well known for its beedi making leaves throughout the world. The purpose of the present study is to assess the effect of Diospyros melanoxylon leaves petroleum ether extract on blood glucose level, lipid level, insulin level, body weight, water and food intake in Streptozotocin (STZ) induced diabetic rats.

Materials and methods

Two different doses of extract AK001 (250 mg/kg) and AK002 (500 mg/kg) of Diospyros melanoxylon leaves were taken to evaluate different activities. The animals were divided into five groups namely normal control, diabetic control, reference group, AK001 and AK002 each containing six animals for in-vivo study. In-vitro study for antiadipogen activity was performed on 3T3-L1 cell line.

Results

The extract showed dose dependent fall in Fasting Glucose Level (FSG) in experimental diabetic animals with significant reduction in food and water intake and increase in body weight. The extract exhibited hypocholesterolemic and hypotriglyceridemic effects while increased level of HDL in diabetes induced rats. In-vitro activity showed more than 75% viability of cells and significant inhibition in differentiated cells as compared to non-differentiate cells in 3T3-L1 cell line. The extract exhibited the concentration-dependent inhibitory effect with an IC₅₀ value of 689.22 μg/ml.

Conclusions

The extract exhibited significant results for antiadipogenic, antidiabetic and hypolipidemic activity both in-vivo and in-vitro and it may prove to be effective for the treatment of both types of diabetes, i.e. Insulin Dependent Diabetes Mellitus (IDDM) and Noninsulin Dependent Diabetes Mellitus (NIDDM).