Main Antifungal Compound Research Articles

Detection and Isolation of Preformed Antifungal Compounds from the Peel of Pyrus bretschneideri Rehd. cv. Pingguoli at Different Stages of Maturity

AbstractEthanol‐dichloromethane crude extract from peel of pear (Pyrus bretschneideri Rehd. cv. Pingguoli) was separated by thin layer chromatographic plates and bioassayed with conidia of Alternaria alternata. The inhibition zones differed significantly in retention factor (Rf) at expanding stage, harvest time and after 100 days of cold storage. The compounds in the inhibition zones were isolated and identified with gas chromatography and mass spectroscopy. Palmitate methyl, oleic acid methyl, linolenic acid methyl and squalene were present at all stages. The concentration of these chemicals was the highest in expanding stage fruit peel and decreased rapidly with fruit development. It is suggested that these compounds may be the main antifungal compounds in the growing fruit. The phthalate alkyl esters occurred at relatively higher concentrations in pear peel at harvest and after 100 days of cold storage. Six phthalate alkyl esters were identified from peel of pear fruit after 100 days of cold storage. It is also supposed that these esters may be the antifungal compounds in postharvest pear.

Antifungal Effects of Volatile Compounds from Black Zira (Bunium persicum) and Other Spices and Herbs

The dish pack method, which measures growth inhibition or promotion effects of volatile compounds on germinating seeds, was applied to measure the antifungal effects of 52 dried samples of spices and herbs against a soil-borne phytopathogenic fungus, Fusarium oxysporum. Black zira showed the strongest effect, followed by cumin and cardamom. Headspace sampling and gas chromatography-mass spectrometry analysis of black zira identified seven volatile compounds, gamma-terpinene, limonene, p-cymene, beta-pinene, alpha-pinene, cuminaldehyde, and myrcene. Among these, cuminaldehyde and p-cymene showed the strongest antifungal activities against F. oxysporum, suggesting roles in the antifungal activity of black zira. The same compounds also showed antifungal activities against another soil-borne phytopathogenic fungus, Verticillium dahliae, and foliar phytopathogenic fungi, Botrytis cinerea and Alternaria mali. The total activity calculated from the concentration of cuminaldehyde contained in black zira and its EC(50) against F. oxysporum demonstrated that cuminaldehyde is the main antifungal compound detected in black zira.

Cyclosporin C is the main antifungal compound produced by Acremonium luzulae.

A strain of Acremonium luzulae (Fuckel) W. Gams was selected in screening new microorganisms for biological control of fruit postharvest diseases, especially gray and blue mold diseases on apples and strawberries. This strain manifests a very strong activity against a large number of phytopathogenic fungi. In this work, the product responsible for this antifungal activity was isolated from modified Sabouraud dextrose broth cultures of A. luzulae. It was purified to homogeneity by reverse-phase column chromatography. On the basis of UV, infrared, and 1H and 13C nuclear magnetic resonance spectra, mass spectral analysis, and the amino acid composition of the acid hydrolysates, the antibiotic was determined to be cyclosporin C. Cyclosporin C showed a broad-spectrum activity against filamentous phytopathogenic fungi but no activity against bacteria or yeasts. Its antifungal activity is only fungistatic. In contrast to Tolypocladium inflatum, another cyclosporin-producing strain, A. luzulae, did not produce additional cyclosporins. This was confirmed by in vivo-directed biosynthesis.

クロクサアリＬａｓｉｕｓ ｆｕｌｉｇｉｎｏｓｕｓ Ｌａｔｒｅｉｌｌｅの大顎腺に含まれる抗菌活性物質の単離と同定

In the mandibular gland of Lasius fuliginosus, several terpenoids were contained. It was found that some of the contents inhibited the spore germination of the plant pathogenic fungi, Colletotrichum lagenarium by a TLC plate bioassay. The antifungal contents were extracted with n-hexane from the heads of workers. The main compound was eluded into 10% ether/hexane when the contents were chromatographed on a silica gel. The isolated compound was analyzed by using gas chromatography, gas chromatography-mass spectrometruy, 1H-NMR, and 13C-NMR. From these spectra the main antifungal compound was identified to be a new one, 3-formyl-7, 11-dimethyl-(2E, 6Z, 10)-dodecatrienal(FDDal). FDDal completely inhibited the spore germination of C. lagenarium at 1 ppm, and that of four species of insect pathogenic fungi at 10 ppm.

The role of phytoalexins in resistance to fusarium wilt in pigeon pea(Cajanus cajan)

Mechanisms of resistance to fusarium wilt(Fusarium udum)were investigated in pigeon pea cultivars from Malawi. Wilt‐susceptible (Malawi local) and wilt resistant (ICP 9145) plants were stem‐inoculated with a spore suspension containing 2·106conidia/ml of the pathogen. Occlusion of a small proportion of infected vessels was observed, but the resistant reaction appeared to depend mainly on rapid phytoalexin synthesis. Four fungitoxic isoflavonoid phytoalexins—hydroxygenistein, genistein, cajanin and cajanol‐were isolated from plants 15 days after inoculation. Cajanol was identified as the main antifungal compound. The concentration of cajanol was 329·4 μg/g in the resistant cultivar as against 88·6 μg/g in the susceptible cultivar 15 days after inoculation. Crude extract from the resistant plants sampled at 24 h after inoculation contained 34·8 μg ml of cajanol. The LD50value of cajanol for spore germination was determined as 35μg/ml. The cajanol content of fungus‐infected ICP 9145 10 days after inoculation totally inhibited conidial germination ofF. udum.