Chemical composition and antifungal activity of Matricaria recutita flower essential oil against medically important dermatophytes and soil-borne pathogens.

OBJECTIVE: Fungal infections are potential public health threats all over the world. In the present study, effect of Matricaria recutita flower essential oil (EO) was evaluated against medically important dermatophytes and opportunistic saprophytes using microbioassay technique. MATERIALS AND METHODS: Flower essential oil (EO) of M. recutita prepared by hydrodistillation was analyzed by gas chromatography/mass spectrometry (GC/MS). The effect of plant EO on the growth of pathogenic dermatophytes and opportunistic saprophytes was assessed using microbioassay technique. In the bioassay, fungi were cultured in 6-well flat-bottom microplates in presence of various concentrations of plant EO (2.5-1000µg/mL) for 4-10days at 28°C. RESULTS: A total of 14 compounds were identified in the plant oil by GC/MS accounting for 97.5% of the oil composition. The main compound identified was chamazulene (61.3%) followed by isopropyl hexadecanoate (12.7%), trans-trans-farnesol (6.9%) and E-ß-farnesol (5.2%). Growth inhibition for the dermatophytes exposed to serial two-fold concentrations of plant EO (2.5 to 80µg/mL) was reported in the range of 3.24 to 68.15% for Microsporum gypseum, 24.48 to 100% for M. canis, 11.40 to 96.65% for Trichophyton mentagrophytes, 27.79 to 100% for T. rubrum and 45.73 to 100% for T. tonsurans. M. recutita EO inhibited the growth of opportunistic saprophytes by 3.98 to 64.29% for Aspergillus flavus, 6.38 to 93.62% for A. fumigatus, 3.52 to 89.45% for A. niger, 6.38 to 77.66% for Trichoderma harzianum and 17.41 to 89.41% for Fusarium oxysporum in serial two-fold concentrations of 15.62 to 1000µg/mL. CONCLUSION: Results of the present study indicate that M. recutita could be considered as a potential candidate for designing effective antifungal formulations suitable for treatment of dermatophytosis and other fungal infections.

Effects of neem leaf extract on production of aflatoxins and activities of fatty acid synthetase, isocitrate dehydrogenase and glutathione S-transferase in Aspergillus parasiticus.

The relationship between the activities of 3 cytosolic enzymes with aflatoxin biosynthesis in Aspergillus parasiticus cultured under different conditions has been investigated in order to find out the role of each enzyme in aflatoxin biosynthesis. Basically the activity of isocitrate dehydrogenase (IDH) was higher in non-toxigenic strains as compared to its counterpart toxigenic fungi (p < 0.05). In contrast, the activities of fatty acid synthase (FAS) as well as glutathione S-transferase (GST) were higher (P < 0.05) in toxigenic strains than that of the non-toxigenic fungi. Aflatoxin production was inhibited in fungi grown in presence of various concentrations of neem leaf extract. Aflatoxin was at its lowest level (>90% inhibition) when the concentration of neem extract was adjusted to 50% (v/v). No significant changes in FAS and IDH activities were observed when aflatoxin synthesis was under restraints by neem (Azadirachta indica) leaf extract. During a certain period of time of culture growth, when aflatoxin production reached to its maximum level, the activity of FAS was slightly induced in the toxigenic strains fed with a low concentration (1.56% v/v) of the neem leaf extract. At the time (96 h) when aflatoxin concentration reached to its maximum levels, the activity of GST in the toxigenic fungi was significantly higher (i.e., 7-11 folds) than that of non-toxigenic strains. The difference was highest in mycelial samples collected after 120 h. However unlike FAS and IDH, GST was readily inhibited (approximately 67%) in mycelia fed with 1.56% v/v of the neem extract. The inhibition reached to maximum of 80% in samples exposed to 6.25-12.5% of the extract. These results further substantiate previous finding that there is a positive correlation between GST activity and aflatoxin production in fungi.