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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.

Ethnopharmacological relevance The resinous exudates of the Commiphora species, known as ‘myrrh’, are used in traditional Chinese medicine for the treatment of trauma, arthritis, fractures and diseases caused by blood stagnation. Myrrh has also been used in the Ayurvedic medical system because of its therapeutic effects against inflammatory diseases, coronary artery diseases, gynecological disease, obesity, etc. Aim of the review Based on a comprehensive review of traditional uses, phytochemistry, pharmacological and toxicological data on the genus Commiphora , opportunities for the future research and development as well as the genus’ therapeutic potential are analyzed. Methods Information on the Commiphora species was collected via electronic search (using Pubmed, SciFinder, Scirus, Google Scholar and Web of Science) and a library search for articles published in peer-reviewed journals. Furthermore, information also was obtained from some local books on ethnopharmacology. This paper covers the literature, primarily pharmacological, from 2000 to the end of December 2011. Results The resinous exudates from the bark of plants of the genus Commiphora are important indigenous medicines, and have a long medicinal application for arthritis, hyperlipidemia, pain, wounds, fractures, blood stagnation, in Ayurvedic medicine, traditional Chinese medicine and other indigenous medical systems. Phytochemical investigation of this genus has resulted in identification of more than 300 secondary metabolites. The isolated metabolites and crude extract have exhibited a wide of in vitro and in vivo pharmacological effects, including antiproliferative, antioxidant, anti-inflammatory and antimicrobial. The bioactive steroids guggulsterones have attracted most attention for their potent hypolipidemic effect targeting farnesoid X receptor, as well as their potent inhibitory effects on tumor cells and anti-inflammatory efficiency. Conclusions The resins of Commiphora species have emerged as a good source of the traditional medicines for the treatment of inflammation, arthritis, obesity, microbial infection, wound, pain, fractures, tumor and gastrointestinal diseases. The resin of C. mukul in India and that of C. molmol in Egypt have been developed as anti-hyperlipidemia and antischistosomal agents. Pharmacological results have validated the use of this genus in the traditional medicines. Some bioassays are difficult to reproduce because the plant materials used have not been well identified, therefore analytical protocol and standardization of extracts should be established prior to biological evaluation. Stem, bark and leaf of this genus should receive more attention. Expansion of research materials would provide more opportunities for the discovery of new bioactive principles from the genus Commiphora .

The idea that many commonly used medicinal plants may lead to the discovery of new drugs has encouraged the study of local knowledge of these resources.An ethnobotanical survey of species traditionally used for the treatment of infectious diseases was undertaken in two areas of northeastern Brazil: one in the Caatinga (dry forest) and another in the Atlantic Forest (humid forest).Initially, diffusion tests using paper disks and subsequently, for extracts presenting significant results (inhibition halos above 15 mm), minimum inhibitory concentrations were determined. The activity was evaluated as a percentage for each species, comparing the diameters of the inhibition halos and the number of positive results against the seven microorganisms studied. Extracts were classified into three categories: strong activity-species with halos exceeding 16 mm, moderate activity-species with halos between 13 mm and 15 mm and low activity-species with halos below 12 mm. We selected 34 species, 20 from the Caatinga and 14 from the Atlantic Forest.In the Caatinga, 50% of the 20 plant extracts studied had strong antimicrobial activity, 25% had moderate activity and 15% had low activity. In the Atlantic Forest, 28.5% of the 14 plant extracts studied showed strong activity, with 14.5% having moderate activity and 28.5% having low activity. The microorganism that was most susceptible to the extracts from the Caatinga, was Mycobacterium smegmatis; 85% of the species tested were able to inhibit its growth. The organism that was susceptible to the highest number of plant species (71%) from the Atlantic Forest was Staphylococcus aureus.Extracts from the Caatinga showed a trend of superior antimicrobial activity compared to the species from the Atlantic Forest, in terms of both inhibiting a greater variety of microorganisms and demonstrating higher activity against susceptible strains.

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.

Ethnopharmacological relevance Ethnobotanical reports on more than 100 southern African medicinal plants with dermatological relevance have been highlighted, yet there is still limited scientific data to support claims for their antimicrobial effectiveness against skin pathogens. Guided by ethnobotanical data, this paper explores the antimicrobial efficacies of southern African medicinal plants used to treat skin ailments. Aim of the study To investigate the antimicrobial properties of southern African medicinal plants against dermatologically relevant pathogens. The study also aimed at providing a scientific rationale for the traditional use of plant combinations to treat skin diseases and the isolation of the bio-active compound from the most active species, Aristea ecklonii (Iridaceae). Materials and methods Organic and aqueous extracts (132) were prepared from 47 plant species and screened for antimicrobial properties against dermatologically relevant pathogens using the micro-titre plate dilution method. Four different plant combinations were investigated for interactive properties and the sum of the fractional inhibitory concentration (ƩFIC) calculated. Isobolograms were used to further investigate the antimicrobial interactive properties of Pentanisia prunelloides combined with Elephantorrhiza elephantina at varied ratios. A bioactivity-guided fractionation process was adopted to fractionate the organic leaf extract of Aristea ecklonii. Results Plants demonstrating notable broad-spectrum activities (MIC values ≤1.00 mg/ml) against the tested pathogens included extracts from Aristea ecklonii, Chenopodium ambrosioides, Diospyros mespiliformis, Elephantorrhiza elephantina, Eucalyptus camaldulensis, Gunnera perpensa, Harpephyllum caffrum, Hypericum perforatum, Melianthus comosus, Terminalia sericea and Warburgia salutaris. The organic extract of Elephantorrhiza elephantina, a plant reportedly used to treat acne vulgaris, demonstrated noteworthy antimicrobial activity (MIC value of 0.05 mg/ml) against Propionibacterium acnes. Similarly, Diospyros mespiliformis reported for its traditional use to treat ringworm, also displayed noteworthy antimicrobial activity against Trichophyton mentagrophytes (MIC 0.10 mg/ml) and Microsporum canis (MIC 0.50 mg/ml). The aqueous root extracts of Pentanisia prunelloides combined (1:1) with Elephantorrhiza elephantina displayed synergistic interactions (ƩFIC values 0.31–0.38) against Staphylococcus aureus, gentamycin–methicillin resistant Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans. Fractionation of Aristea ecklonii resulted in the isolation of the known bio-active compound, plumbagin, displaying noteworthy antimicrobial activity (MIC range between 2.00 μg/ml and 16.00 μg/ml). Conclusion Most of the plant extracts demonstrated pathogen specific antimicrobial effects with a few exhibiting broad-spectrum activities. Positive antimicrobial effects noted for plants such as Elephantorrhiza elephantina and Diospyros mespiliformis used for acne vulgaris and ringworm infections, respectively, give some validation to their reported traditiona l uses. Synergistic interactions noted for Pentanisia prunelloides combined with Elephantorrhiza elephantina validate an enhanced antimicrobial effect when used in combination. Noteworthy antimicrobial activities (MIC range between 2.00 μg/ml and 16.00 μg/ml) were observed for plumbagin isolated from Aristea ecklonii.