Antimicrobial activity of selected Iranian medicinal plants against a broad spectrum of pathogenic and drug multiresistant micro-organisms.

The antimicrobial activities of 44 methanolic extracts from different parts of Iranian indigenous plant species used in traditional medicines of Iran were tested against a panel of 35 pathogenic and multiresistant bacteria and 1 yeast. The antimicrobial efficacy was determined using Müller-Hinton agar in Petri dishes seeded by a multiple inoculator and minimal inhibition concentration (MIC) method. The 21 most active extracts (MIC < 0·3 mg ml(-1) for one or several micro-organisms) were submitted to a more refined measurement. The best antibacterial activity was obtained by 10 plants. Microdilution assays allowed to determinate the MIC and MBC of the 21 most active extracts. The lowest achieved MIC value was 78 µg ml(-1), with 4 extracts. This work confirms the antimicrobial activity of assayed plants and suggests further examination to identify the chemical structure of their antimicrobial compounds. Significance and impact of the study: This study describes the antimicrobial screening of Iranian plant extracts chosen according to traditional practice against 36 microbial strains, from reference culture collections or recent clinical isolates, and enables to select 4 candidates for further chemical characterization and biological assessment: Dorema ammoniacum, Ferula assa-foetida, Ferulago contracta (seeds) and Perovskia abrotanoides (aerial parts). This may be useful in the development of potential antimicrobial agents, from easily harvested and highly sustainable plant parts. Moreover, the weak extent of cross-resistance between plant extracts and antibiotics warrants further research and may promote a strategy based on less potent but time-trained products.

Effects of Microdesmis keayana roots on sexual behavior of male rats.

In the present study, the aphrodisiac properties of Microdesmis keayana J. Léonard root extract and major isolated alkaloids were evaluated by observing the sexual behavior of male rats. Aqueous extract (150mg/kg body weight) and pure alkaloids (3mg/kg body weight) were administered orally by gavage to male rats. Latent times of observation, intromission and ejaculation, mounting behavior, number of intromissions and mating performances were evaluated and compared to those obtained with untreated rats in the presence of receptive and non-receptive females. The results have shown that aqueous extract and alkaloids of M. keayana stimulate sexual parameters in rats' sexual behavior. A short-term toxicity study undertaken to establish the therapeutic index of aqueous extract, showed that a high dose of the extract (2g/kg body weight) caused no mortality or changes in rats' behavior.

Benzophenone glycosides from Gnidia involucrata.

Six compounds have been isolated from the methanol extract of the aerial parts of Gnidia involucrata (Thymelaeaceae). They were identified as 2,3,4',5,6-pentahydroxybenzophenone-4-C-glucoside and 2,4',6-trihydroxy-4-methoxybenzophenone-2-O-glucoside, together with mangiferin, kaempferol-3-O-glucoside, yuankanin and manniflavanone by chemical and spectroscopic means. The structures of three additional C-glycosyl flavones--vitexin, isovitexin and isoorientin--were determined on-line by LC/UV/APCI-MSn analysis of the crude extract.

Triterpene saponins from Randia formosa.

Seven new triterpenoid saponins, randiasaponins I (1), II (2), III (3), IV (4), V (5), VI (6) and VII (7) as well as two known ones, ilexoside XXVII (8) and ilexoside XXXVII (9), were isolated from the methanolic extract of the leaves of Randia formosa. The structures of the new saponins were established as 3-O-alpha-L-arabinopyranosyl-3 beta,19 alpha,23-trihydroxyursa-12,20(30)-dien-28-oic acid 28-beta-D-glucopyranosyl ester (1), 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl rotundic acid (2), 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl pomolic acid 28-beta-D-glucopyranosyl ester (3), 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl pomolic acid 28-beta-D-glucopyranosyl ester (4), 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl siaresinolic acid 28-beta-D-glucopyranosyl ester (5), 3-O-alpha-L-arabinopyranosyl ilexosapogenin A 28-beta-D-glucopyranosyl ester (6), and 3-O-beta-D-glucopyranosyl ilexosapogenin A 28-beta-D-glucopyranosyl ester (7), based on spectral and chemical evidence. Besides the saponins, two common flavonoids kaempferol 3-O-rutinoside and rutin were also isolated.

Two 6-substituted 5,6-dihydro-alpha-pyrones from Ravensara anisata.

The leaves and bark dichloromethane extracts of Ravensara anisata showed antifungal activity against the yeast Candida albicans and the phytopathogenic fungus Cladosporium cucumerinum in bioautographic TLC assays. Activity-guided fractionation afforded two new alpha-pyrones: 6R*-(4R*-acetoxy-2S*-hydroxy- 8-phenyloctyl)-5,6-dihydro-2-H-pyran-2-one and 6R*-(2S*-acetoxy-4R*- hydroxy-8-phenyloctyl)-5,6-dihydro-2-H-pyran-2-one. Their structures have been established by NMR spectroscopy, chemical methods and X-ray crystallographic analysis. The antifungal activity against C. albicans and C. cucumerinum was determined for both compounds.

Annosenegalin and annogalene: two cytotoxic mono-tetrahydrofuran acetogenins from Annona senegalensis and Annona cherimolia.

Two new cytotoxic mono-tetrahydrofuran acetongenins, annosenegalin and annogalene, have been isolated from the cytotoxic methanolic extract of Annona senegalensis and A. cherimolia seeds. Their structures were established on the basis of 1D and 2D NMR spectroscopic techniques. Annosenegalin belongs to the rare type of C37 mono-tetrahydrofuran acetogenins, and annogalene is an olefinic acetogenin.

Acetogenins from Annonaceae, inhibitors of mitochondrial complex I.

One-hundred and twenty-eight different linear, epoxy, mono-tetrahydrofuran, bis-tetrahydrofuran or tri-tetrahydrofuran acetogenins have been isolated from the Annonaceae. These new secondary metabolites are potent cytotoxic inhibitors of the mitochondrial NADH:ubiquinone oxidoreductase (complex I of the respiratory chain).

Cytotoxic and antiparasitic activity from Annona senegalensis seeds.

Several extracts of Annona senegalensis (Annonaceae) seeds were tested for antiparasitic activity against Leishmania major, Leishmania donovani, Trypanosoma brucei brucei, and for cytotoxic activity against KB and VERO cell lines. Fractionation of seeds extracts was mainly guided by means of a biocidal assay against Artemia salina nauplii. The biological activities resulted from extract-isolated acetogenins.