A bioautographic agar overlay method for the detection of antifungal compounds from higher plants

Abstract

A simple bioautographic agar overlay assay using Candida albicans as the indicator organism for the detection and activity‐guided fractionation of antifungal compounds by thin layer chromatography has been developed. Inhibition of fungal growth was assessed by the detection of dehydrogenase activity with thiazolyl blue (methylthiazolyltetrazolium chloride; MTT). A series of clinically used antimycotic agents were tested in order to determine the sensitivity of the assay. The compatibility of the agar overlay technique with chemically modified silica gel (Diol and RP‐18) plates and with various organic solvents was evaluated. The methodology is also applicable to the search for antibacterial compounds, as shown with Bacillus subtilis as a test organism.

New bioactive metabolites produced by Phomopsis cassiae, an endophytic fungus in Cassia spectabilis

“…7 This polyketide presents sclerotinin skeleton, whose biosynthesis was proposed by Barber et al 8 and Tokoroyama and Kubota. 10 The antifungal activity of compounds 1-3 against the phytopatogenic fungi Cladosporium cladosporioides and C. sphaerospermum was evaluated by bioautography 11,12 and the detection limit for the compounds 1 and 2 was 1.0 μg, the same as for the positive control nystatin. Citotoxity of the compounds 1, 2 and 3 against human cervical tumor cell line (HeLa) were tested using the MTT assay.…”

Activity of extracellular compounds of Pseudomonas sp. against Xanthomonas axonopodis in vitro and bacterial leaf blight in eucalyptus

“…The TLC bioautography test (Rahalison et al, 1991) was performed to determine qualitatively the antibiotic activity of all fractions. The TLC plates were each placed in a Petri dish 90 mm in diameter containing 20 mL of NA plus 1 mL cell suspension of X. axonopodis (10 8 CFU mL -1 , D.O 0.1, λ= 590 nm) in the log phase.…”

Morphological and chemical diversity in the Type IV glandular trichomes of Solananeae (S. sisymbrifolium and N. glauca) as germplasm resources for agricultural and food uses

“…Such substances do not diffuse in agar, a circumstance that can result in false negatives. Prior work from our group with a modification of Rahalison's technique (Rahalison et al 1991;Larramendi et al 1998) has shown that Bioautography on TLC is particularly useful to assay bioactive compounds present in complex mixtures, as shown in Figure 4, with a quantitative perspective.…”