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Fungal infections of plants cause major difficulties in agricultural food production and in storage of food especially due to the development of fungal resistance and the negative environmental impact of some chemical fungicides. The aim of this study was to develop a plant-based product that could be used to control plant fungal pathogens in agriculture. Melianthus comosus is a weedy shrub endemic to southern Africa. Its acetone leaf extract had good activity against plant fungal pathogens. We investigated the efficiency of ten extractants with varying polarities. Acetone was the best with a 52 times higher selectivity for antifungal activity against eight important fungal pathogens than methanol. The average minimum inhibitory concentration (MIC) was 100 μg/ml varying from 20 to 310 μg/ml against eight fungal pathogens. By using open column silica gel chromatography and bioautography the major antifungal compound was isolated and characterized as oleanolic acid. Two methods based on selective extraction and solvent–solvent extraction were used to potentize the activity of the extract by removing inactive polar and non-polar compounds. The product had an average MIC of 66 μg/ml varying between 20 and 160 μg/ml against 10 fungal pathogens. The product had low water solubility and was stable for a month at 55ᵒC. When used in a field trial on comfrey ( Symphytum officinale ) with a natural rust infection it was much more effective at a concentration of 0.2 mg/ml than the commercial product containing dicarboximide at a concentration of 1.5 mg/ml. The Melianthus extract treatment led to 50 infected leaves in the bed compared to 250 infected leaves of the dicarboximide treatment and extensive infection in the negative control. It appears that this product has the potential to be used in agricultural practice. This plant may become a new crop that may be useful for organic cultivation. [ABSTRACT FROM AUTHOR]

Ethnopharmacological relevance Fagara tessmannii is a shrub of the African rainforests used to treat bacterial infections, cancers, swellings and inflammation. In the present study, the methanol extract from the leaves (FTL), bark (FTB), and roots (FTR) of this plant as well as fractions (FTR1-5) and compounds isolated from FTR namely β -sitosterol-3- O-β- d -glucopyranoside ( 1 ), nitidine chloride ( 2 ) and buesgenine ( 3 ), were tested for their antimicrobial activities against a panel of Gram-negative bacteria including multidrug resistant (MDR) phenotypes. Materials and methods The broth microdilution method was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the above samples; Column chromatography was used for the fractionation and purification of the roots extract whilst the chemical structures of compounds were determined using spectroscopic techniques. Results Results of the MIC determinations indicated that the crude extracts from the roots as well as fraction FTRa4 were active on all the 26 tested bacterial strains. MIC values below 100 µg/mL were obtained with roots, leaves and bark extract respectively against 30.8%, 15.4% and 11.5% tested bacteria. The lowest MIC value below of 8 µg/mL was obtained with extract from the roots against Escherichia coli MC100 strain. The lowest MIC value of 4 µg/mL was also obtained with compound 3 against E. coli AG102 and Klebsiella pneumoniae ATCC11296 Conclusions The present study demonstrates that F. tessmannii is a potential source of antimicrobial drugs to fight against MDR bacteria. Benzophenanthrine alkaloids 2 and 3 are the main antibacterial consituents of the roots of the plant. [ABSTRACT FROM AUTHOR]

Ethnopharmacological relevance Culinary herbs and spices are widely used ethnomedically across Africa. They are traditionally employed in the treatment of several ailments including inflammation disorders, pain alleviation and infectious diseases. Pharmacological studies are necessary to provide a scientific basis to substantiate their traditional use and safety. In this study, the 15-lipoxygenase inhibitory, antioxidant, antimycobacterial and the cytotoxic activities, total phenolic and flavonoid contents of fourteen edible plants were investigated. Materials and methods The 15-lipoxygenase inhibitory activity was evaluated by the ferrous oxidation-xylenol orange (FOX) assay method. The antioxidant activity was determined using free-radical scavenging assays. The antimycobacterial activity was determined by a broth microdilution method against three species of mycobacteria: Mycobacterium smegmatis , Mycobacterium aurum and Mycobacterium fortuitum using tetrazolium violet as growth indicator. The cytotoxicity was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on Vero monkey kidney cells. Results All the extracts tested had some 15-lipoxygenase inhibitory activity ranging from 32.9 to 78.64%. Adansonia digitata (fruit) had the highest antioxidant capacity (IC 50 values of 8.15 μg/mL and 9.16 μg/mL in the DPPH and ABTS assays respectively; TEAC of 0.75 in the FRAP assay) along with the highest amount of total phenolics (237.68 mg GAE/g) and total flavonoids (16.14 mg E/g). There were good correlations between DPPH and ABTS values ( R 2 0.98) and between total phenolics and total flavonoids ( R 2 0.94). Tamarindus indica had significant antimycobacterial activity against Mycobacterium aurum (MIC 78 μg/mL). As could be expected with edible plants, all the extracts had a relatively low cytotoxicity with LC 50 values higher than 102 μg/mL with the exception of the two Aframomum species (33 and 74 μg/mL). Conclusions This study provides scientific support for some of the the traditional uses and the pharmacological activities of the culinary herbs and spices investigated. The results suggest that increasing intake of some of these herbs may be useful in preventing or reducing the progression of lifestyle-related diseases. The diversity of the pharmacological activities of the extract from the fruit of Adansonia digitata suggested that this plant might be valuable for application in human and animal health. [ABSTRACT FROM AUTHOR]

Background: Entada abyssinica is a plant traditionally used against gastrointestinal bacterial infections. Eight compounds including three flavonoids, three terpenoids, a monoglyceride and a phenolic compound isolated from E. abyssinica were investigated for their cytotoxicity, antibacterial and antioxidant activity., Results: Compounds 7 and 2 had remarkable activity against Salmonella typhimurium with the lowest respective minimum inhibitory concentration (MIC) values of 1.56 and 3.12 µg/mL. The antioxidant assay gave IC 50 values varied from 0.48 to 2.87 μg/mL in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, from 2.53 to 17.04 μg/mL in the 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) assay and from 1.43 to 103.98 µg/mL in the FRAP assay. Compounds had relatively low cytotoxicity (LC 50 values ranging from 22.42 to 80.55 µg/mL) towards Vero cells. Ursolic acid had the most potent cytotoxicity against THP-1 and RAW 264.7 cells with LC 50 values of 9.62 and 4.56 μg/mL respectively, and selectivity index values of 7.32 and 15.44 respectively., Conclusion: Our findings suggest that among the terpenoid and flavonoid compounds studied, entadanin (compound 7) possess tremendous antibacterial activity against S. typhimurium and could be developed for the treatment of bacterial diseases.