Antimicrobial activity of medicinal plants against oral microorganisms

Ethanol extracts of eight plant species used traditionally in South Africa for the treatment of oral diseases were investigated for in vitro antimicrobial activity against oral pathogens namely Actinobacillus actinomycetemcomitans, Actinomyces naeslundii, Actinomyces israelii, Candida albicans, Porphyromonus gingivalis, Privotella intermedia and Streptococcus mutans using the disk diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ethanol extracts were determined against these microorganisms using micro dilution. The cytotoxicity and therapeutic index (TI) of selected active extracts were also determined. Out of eight plants, six (Annona senegalensis, Englerophytum magalismontanum, Dicerocarym senecioides, Euclea divinorum, Euclea natalensis, Solanum panduriforme and Parinari curatellifolia) exhibited MIC values ranging from 25.0 mg/ml to 0.8 mg/ml. Gram negative bacteria were found to be more resistant to the plant extracts than Gram positive bacteria, except for Euclea natalensis which inhibited all three Gram negative bacteria tested in this study. All plant extracts showed moderate cytotoxicity on the Vero cell line. The fifty percent inhibitory concentration (IC₅₀) of all plants tested range from 92.3 to 285.1 μg/ml.     

Iminosugar-producing Thai medicinal plants

Alpha-1-C-hydroxymethylfagomine (7), 3-O-beta-D-glucopyranosyl-DMDP (12), and 2,5-dideoxy-2,5-imino-D-glucitol (13) were isolated from the Thai traditional crude drug "Non tai yak" (Stemona tuberosa), which also contains a high concentration level of alpha-homonojirimycin (0.1% dry weight). "Thopthaep" (Connarus ferrugineus) and "Cha em thai" (Albizia myriophylla) contained 1-deoxymannojirimycin (DMJ) (10) at levels of 0.083% (dry weight) and 0.17% (dry weight), respectively. 2-O-alpha-D-Galactopyranosyl-DMJ (20), 3-O-beta-D-glucopyranosyl-DMJ (21), 1,4-dideoxymannojirimycin (17), 1,4-dideoxyallonojirimycin (18), and 1,4-dideoxyaltronojirimycin (19) from C. ferrugineus and 2-O-beta-D-glucopyranosyl-DMJ (22) and 4-O-beta-D-glucopyranosyl-DMJ (23) from A. myriophylla were isolated as new compounds.     

Diuretic effects of selected Thai indigenous medicinal plants in rats

Extracts of five indigenous Thai medicinal having ethnomedical application in the treatment of dysuria were investigated for their diuretic activity. Root extracts of Ananas comosus and Carica papaya, given orally to rats at a dose of 10 mg/kg, demonstrated significantly increased urine output (P < 0.01) which was 79 and 74%, respectively, of the effect of an equivalent dose of hydrochlorothiazide. Both plant extracts gave similar profiles of urinary electrolyte excretion to that of the hydrochlorothiazide. The analyses of the urinary osmolality and electrolyte excretion per unit time suggest the observed effect of A. comosus was intrinsic, whereas that of C. papaya may have resulted from a high salt content of this extract. However, our experimental evidence on the diuretic activities of the other three plants did not parallel their local utilization for dysuria. It was found that the rhizome of Imperata cylindrica apparently inhibited the urination of rats whereas the rhizome of Cyperus rotundus and the stem of Averrhoa carambola failed to demonstrate any diuretic activities. These results indicate that two of the plants investigated exert their action by causing diuresis. The other three plants need further investigation to determine their effectiveness in the treatment of dysuria.     

Antimicrobial properties of Honduran medicinal plants

Ninety-two plants used in the traditional pharmacopoeia of the Pech and neighboring Mestizo peoples of central Honduras are reported. The results of in vitro antimicrobial screens showed that 19 of the extracts from medicinal plants revealed signs of antifungal activity while 22 demonstrated a measurable inhibitory effect on one or more bacterial cultures. Bioassay-guided fractionation of extracts from Mikania micrantha, Neurolaena lobata and Piper aduncum produced weak to moderately active isolates. The broad spectrum of activity of the extracts helps to explain the widespread use of these plants for wound healing and other applications.     

Antimicrobial screening of some medicinal plants

Plants were collected from several states of México and dried in the shade, ground and extracted with water, methanol or chloroform. The antimicrobial activity of the crude extracts was tested against E. coli, S. aureus, S. lutea, P. vulgaris and C. albicans using the agar diffusion technique. A methanol extract of E. polistachia showed antimicrobial activity against all microorganisms used in this study to doses in the order of 400 μg. © 1997 John Wiley & Sons, Ltd.     

Antimicrobial activity of South African medicinal plants

This paper reviews the antimicrobial research undertaken on South African medicinal plants during the period 1997-2008. Antimicrobial methods (disc diffusion, minimum inhibitory concentration (MIC), bio-autography) are briefly discussed and an analysis of the publications reviewed indicates that the majority of papers use MIC assays for antimicrobial determination. Antimicrobial investigations on extracts are presented where the most active plants are identified from screening publications. A summary of some bioactive compounds are given with data restricted to papers reporting quantitative antimicrobial activity equivalent to or below 200 microg/ml. Antimicrobial activities on the essential oils of indigenous medicinal aromatic plants are also reviewed. An overview is given on what activities (extracts, compounds and oils) should be considered noteworthy for publication. Studies focusing on geographical ethnobotany, specific pathogenesis, formulation aspects and in vivo investigations are examined. Future recommendations to consider include pathogen selection, interactive studies and dosage administrations.     

Antimicrobial activities of southern Nepalese medicinal plants

In an ethnopharmacological screening of selected medicinal plants used in Nepal, methanol extracts from 20 plant species were assayed for activity against eleven strains of bacteria and four strains of fungi. Duplicate assays were conducted with and without exposure to ultraviolet (UV)-A radiation to test for light-activated or light-enhanced activity. Fifteen of the extracts showed activity against bacteria and fourteen showed activity against fungi. Five extracts were active only when exposed to UV-A light, and the antibiotic or antifungal effect of five extracts was enhanced upon exposure to light. Two of the most active extracts were from plants used to treat diarrhoea and dysentery. Bark from both Terminalia alata (Combretaceae) and Mallotus phillppensis (Euphorbiaceae) was active against Gram-positive and Gram-negative bacteria.     

Antimicrobial activity of selected Peruvian medicinal plants

The antimicrobial activity of 36 ethanol extracts from 24 plants, all of them currently used in the Peruvian traditional medicine for the treatment of several infectious and inflammatory disorders, was tested by means of the agar-well diffusion assay against four bacteria (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) and four fungi (Candida albicans, Trichophyton mentagrophytes, Microsporum gypseum and Sporothrix schenckii). Twenty-five (69%) extracts showed some degree of antimicrobial activity against at least one microorganism. The plants with the greatest antimicrobial activity were Cestrum auriculatum L. Heritier (Solanaceae), Iryanthera lancifolia Ducke Suesseng (Myristicaceae), Lepechinia meyenii (Walp.) Epling (Lamiaceae) and Ophryosporus peruvianus (Gmelin) King & H. Rob. (Asteraceae).     

Screening for phosphodiesterase inhibitory activity of Thai medicinal plants

INTRODUCTION: Phosphodiesterases (PDEs) are a group of enzymes that have powerful effects on cellular signaling because they regulate the second messenger, cAMP or cGMP. PDE inhibitors have been used for treatment of many indications such as cardiovascular diseases, chronic obstructive pulmonary diseases, erectile dysfunction and pulmonary hypertension. THE AIM OF THE STUDY: The aim of the study was to search for sources of PDE inhibitors from Thai biodiversity. MATERIALS AND METHODS: Some Thai medicinal plants used as aphrodisiac and neurotonic agents together with plants from Leguminosae collected from the North of Thailand were screened for PDE inhibitory activity using a radioassay. RESULTS: Seven from nineteen aphrodisiac and neurotonic plants as well as three from twelve Leguminosae plants showed potent PDEs inhibitory activity. The concentrations that could inhibit 50% PDE activity (IC(50)) of the active extracts were determined in comparison to the standard inhibitor, 3-isobutyl-1-methylxanthine (IBMX). Betula alnoides, Hiptage benghalensis, Leea indica and Senna surrattensis showed IC(50) values in the range of microgram per milliliter while IBMX standard showed an IC(50) value of 0.68+/-0.13 microg/ml. CONCLUSION: Thai biodiversity was the great sources of PDE inhibitors.     

Antimicrobial and phytochemical studies on 45 Indian medicinal plants against multi-drug resistant human pathogens

Ethanolic extracts of 45 Indian medicinal plants traditionally used in medicine were studied for their antimicrobial activity against certain drug-resistant bacteria and a yeast Candida albicans of clinical origin. Of these, 40 plant extracts showed varied levels of antimicrobial activity against one or more test bacteria. Anticandidal activity was detected in 24 plant extracts. Overall, broad-spectrum antimicrobial activity was observed in 12 plants (L. inermis, Eucalyptus sp., H. antidysentrica, H. indicus, C. equistifolia. T. belerica, T. chebula, E. officinalis, C. sinensis, S. aromaticum and P. granatum). No correlation was observed between susceptibility of test strains with plant extracts and antibiotic resistance behaviour of the microbial strains (Staphylococcus aureus, Salmonella paratyphi, Shigella dysenteriae, Escherichia coli, Bacillus subtilis, Candida albicans). Qualitative phytochemical tests, thin layer chromatography and TLC-bioautography of certain active extracts demonstrated the presence of common phytocompounds in the plant extracts including phenols, tannins and flavonoids as major active constituents.     

Antimicrobial evaluation of some medicinal plants for their anti-enteric potential against multi-drug resistant Salmonella typhi

Screening was done of some plants of importance in the Ayurvedic system of traditional medicine used in India to treat enteric diseases. Fifty four plant extracts (methanol and aqueous) were assayed for their activity against multi-drug resistant Salmonella typhi. Strong antibacterial activity was shown by the methanol extracts of Aegle marmelos, Salmalia malabarica, Punica granatum, Myristica fragrans, Holarrhena antidysenterica, Terminalia arjuna and Triphal (mixture of Emblica of fi cinalis, Terminalia chebula and Terminalia belerica). Moderate antimicrobial activity was shown by Picorhiza kurroa, Acacia catechu, Acacia nilotica, Cichorium intybus, Embelia ribes, Solanum nigrum, Carum copticum, Apium graveolens, Ocimum sanctum, Peucedanum graveolens and Butea monosperma.     

Antimicrobial activity of some medicinal plants of the island Soqotra

Twenty-five selected plants belonging to 19 families were collected from different localities of the island Soqotra, dried and extracted with the solvents chloroform, methanol and hot water to yield 80 extracts. The extracts were tested for their antimicrobial activity against several Gram-positive and Gram-negative bacteria and against one yeast species using agar diffusion method. Antibacterial activity was demonstrated especially against Gram-positive bacteria including multiresistant Staphylococcus strains. The greatest activity was exhibited by the methanolic extracts of Boswellia elongata, Boswellia ameero, Buxus hildebrandtii, Commiphora parvifolia, Jatropha unicostata, Kalanchoe farinacea, Pulicaria stephanocarpa, Punica protopunica, Withania adunensis and Withania riebeckii. Only the methanolic extract of Buxus hildebrandtii displayed significant antifungal activity.     

Hypoglycemic activity of Thai medicinal plants selected from the Thai/Lanna Medicinal Recipe Database MANOSROI II

Ethnopharmacological relevance

Five medicinal plants including Anogeissus acuminata (Roxb. ex DC.) Gills. & Perr. (Combretaceae), Catunaregam tormentosa (Bl. ex DC.) Tirveng (Rubiaceae), Dioecrescis erythroclada (Kurz) Tirveng. (Rubiaceae), Mimosa pudica Linn. var. hispida Bren. (Fabaceae), and Rauwolfia serpentina (L). Benth. ex Kurz. (Apocyanaceae), which have been traditionally used for the treatment of diabetes mellitus and other diseases for several generations by the Thai-Lanna people in the Northern part of Thailand were investigated for their hypoglycemic activity in normoglycemic and alloxan, induced diabetic mice.

Materials and methods

The aqueous extracts of the selected five medicinal plants were tested for their phytochemicals, free radical scavenging activity and hypoglycemic activity on 18 h fasted normoglycemic and alloxan induced diabetic mice over a period of 4 h comparing with the standard anti-diabetic drugs (insulin and glibenclamide) using two way analysis of variance (ANOVA) as analytical tool. Phytochemical analysis was performed using the standard methods while 2,2-diphenyl-1-picrylhydrazine (DPPH) was used to test for free radical scavenging activities of the medicinal plant extracts.

Results

Phytochemicals detected in the extracts were glycosides, xanthones, tannins, alkaloids and saponins. Anogeissus acuminata showed the highest free radical scavenging activity with the IC₅₀ value of 11.00 μg/mL which was 4 folds of the standard ascorbic acid. Significant reduction in fasting blood glucose (FBG) levels of the normoglycemic mice was observed at 4 and 3 h with the extracts of Mimosa pudica (200 mg/kg bw) and Rauwolfia serpentina (100 mg/kg bw), and percentage decreases of 46.15 and 27.94% which were 0.76 and 1.47; 0.53 and 0.91 folds of insulin and glibenclamide, respectively. In alloxan induced diabetic mice, all extracts showed significant (p < 0.05) hypoglycemic activity, with the maximum FBG reduction of 78.96 at 100 mg/kg bw shown by Anogeissus acuminata at the 4 h. The hypoglycemic activity of Anogeissus acuminata was comparable to insulin (1.1 fold), but more potent than glibenclamide (1.76 folds).

Conclusions

Medicinal plants selected from the Thai/Lanna Medicinal Plant Recipe Database MANOSROI II showed hypoglycemic activity in normoglycemic and alloxan induced diabetic mice. This study confirmed the traditional use of these medicinal plants for the treatment of diabetes mellitus and the thiazolidiendiones mimic hypoglycemic effects of the medicinal plants was suggested.     

Antimicrobial activity of some medicinal plants of the Cerrado, Brazil

In order to determine the potential of Cerrado plants as sources of antimicrobial activity, the phytochemical screening of ethanol extracts from Virola surinamensis, Qualea grandiflora, Alchornea castaneifolia, Hancornia speciosa and Curatella americana traditionally used in folk medicine are reported.     

Antimalarial effects of eight African medicinal plants

Crude hot water extracts from eight medicinal plants collected in Togo, West Africa, were examined for antimalarial properties against Plasmodium falciparum using an in vitro test. The activity differed with the plant species with extracts of Cassia siamea, Jatropha gossypiifolia and Pavetta crassipes capable of 100% inhibition.     

Antimicrobial activity of certain Indian medicinal plants used in folkloric medicine

Fifty medicinal plants belonging to 26 families were studied for their antimicrobial activity. Among 50 plants tested, 72% showed antimicrobial activity. About 22 plant extracts from 15 families exhibited activity against both Gram-positive and Gram-negative bacteria. Fourteen plants belonging to 11 families did not show activity against any of the bacteria tested. Only nine plant extracts showed antifungal activity. The bulb extracts of A. cepa and A. sativum exhibited activity against both filamentous and non-filamentous fungus. Eight plant extracts belonging to seven families exhibited both antibacterial and antifungal activity.     

Antimicrobial screening of medicinal plants from Baja California Sur, Mexico

The ethanolic extracts of 72 plants belonging to 35 different families, and used in traditional medicine in Baja California Sur (México), were tested for antimicrobial activity in vitro using the filter paper disk assay method. Activity against Staphylococcus aureus, Bacillus subtilis, Streptococcus faecalis (Gram-positive microorganisms), Escherichia coli (Gram-negative microorganisms) and Candida albicans (yeast) is discussed.     

In vitro cytotoxic activity of Thai medicinal plants used traditionally to treat cancer

The SRB assay was used to test cytotoxicity against three human cancer cell lines and one normal cell line of 11 Thai medicinal plant species used by traditional doctors in treating cancer patients. The extraction procedures used were similar to those practised by Thai traditional doctors (ethanolic and water extracts). Extracts were tested against the human large cell lung carcinoma cell line COR-L23, the human breast adenocarcinoma cell line MCF-7 and human colon adenocarcinoma cell line LS-174T and normal human keratinocytes SVK-14. The results showed that three plants; Dioscorea membranacea Pierre ex Prain & Burkill, Dioscorea birmanica Prain & Burkill (Dioscoreaceae) and Siphonodon celastrineus Griff. (Celastraceae), exhibited high cytotoxic activity showing a certain degree of selectivity against the different cell types.