Effect of Oriental Medicinal Plant Extracts on Spore Germination ofAlternaria brassicicolaand Nature of Inhibitory Substances from Speedweed

Abstract

Among 65 species of oriental medicinal plants tested, 39 contained substances inhibitory to conidial germination of Alternaria brassicicola, with the most inhibitory extract from speedweed (Polygonum perfoliatum). The inhibitory substances in dried speedweed were insoluble in water. However, the inhibitors were readily extracted with ethanol or methanol, but not with acetone, ether, or chloroform. The ethanol extract was very effective in controlling black leaf spot of spoon cabbage, Brassica campestris subsp. chinensis, caused by A. brassicicola. The inhibitory effect of the extract was not affected by treatment with anion exchange resins, but was partially reduced by cation exchange resins, indicating the presence of two inhibitory substances in the extract, one with a positive charge and the other with no charge on its molecule. The inhibitory substances in the extract were dialyzable with molecular weight minimums of 10,000 or 1,000, but not 500 or 100, suggesting that both inhibitors have molecular weights between 500 and 1,000.

Screening for Antifungal Activities of Some Medicinal Plants used Traditionally in Saudi Arabia

“…This current experiment provided some scientific justification for the utilization of extracts from these plants to treat fungal diseases. Of the 65 species of oriental medicinal plants tested by Ho et al (2007),60% contained substances inhibitory t o spore germination of Alternaria brassicicola and they suggested that oriental medicinal plants are a good source for obtaining desirable substances for controlling pathogenic fungi. No toxicity or antitumor activity were recorded for the tested plant extracts up to 600 pg/ml except for A.…”

Control of lethal browning of tissue culture plantlets of Cavendish banana cv. Formosana with ascorbic acid

“…The pH of mixture was adjusted to 5.7 and filtered through Whatman no. 1 filter paper after shaking for 30 min (Ho et al 2007). To study the effect of antioxidant on the incidence of lethal browning of banana tissue culture plantlets, 10 ml of 0.01% ascorbic acid solution was added to the surface of SM medium in each flask after autoclaving.…”

Control of plant diseases with secondary metabolite of Clitocybe nuda

“…To test the nature of the inhibitor in the culture filtrate of C. nuda (LA82), 10 g each of Diaion SK1B cation exchange resins (equivalent to Amberlite IR-120), Diaion SA12A anion exchange resins (equivalent to Amberlite IRA-420) (Tai-Young Chemical Co., Kaohsiung, Taiwan), or activated charcoal (Sigma-Aldrich, USA) were washed with 100 ml of distilled water four times by shaking for a 6-h period to remove possible inhibitory substances [25]. Fifty milliliters of culture filtrate was shaken with either 5 g of each type of resins or 5 g of activated charcoal in a 250-ml flask at 150 rpm for 24 h and filtered through a Whatman No.…”

“…Fifty milliliters of culture filtrate was shaken with either 5 g of each type of resins or 5 g of activated charcoal in a 250-ml flask at 150 rpm for 24 h and filtered through a Whatman No. 1 filter paper [25]. The treated culture filtrates were used for germination tests.…”

“…Five milliliters of culture filtrate was placed in a dialysis tubing with a molecular weight cut-off of 100, 500 or 1000 (Spectrum Medical Industries Inc., Los Angeles, CA), and dialyzed at 24 8C against 4000 ml of distilled water that was changed four times over a 24-h period [25]. After dialysis the filtrates were tested for spore germination as described above.…”