Effect of Zataria multiflora Boiss. essential oil on colony morphology and ultrastructure of Aspergillus flavus.

The mode of inhibitory action of Zataria multiflora Boiss. essential oil (EO) on the fungus, Aspergillus flavus, was studied by colony morphology examination, light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The EO at concentrations used in this study suppressed the size of the colony as well as sporulation. SEM of mycelia treated with given concentrations of EO showed morphological alterations ranging from loss of turgidity and uniformity of mycelia at low concentrations of EO to evident destruction of the hyphae at higher concentration of EO. Semi-thin sections of mycelia exposed to different concentrations of EO were analysed by light microscopy and revealed that the major change at level as low as 50 ppm of EO was limited to vacuolisation of cytoplasm resulting in cell swelling, while at higher concentrations, detachment of the cell membrane from the cell wall, deformation of mycelia and shedding the cytoplasm from the cell were the main alterations. These damages were well documented by TEM, which showed that the main sites of action of EO were the plasma membrane and cell wall. In conclusion, morphological and structural changes observed in this study may be one of the mechanisms involved in growth inhibition of the fungi and reducing aflatoxin production.

Comparison of flame atomic absorption spectrometry (FAAS) and Cerimetric methods for the determination of ferrous sulfate content of some pharmaceutical products.

The iron content of ferrous sulphate syrup and tablet, ferroglobin, and Fefol were determined by both titration with cerium (Cerimetric method) proposed by united state pharmacopeias and flame atomic absorption spectrometry (FAAS). In FAAS both external calibration and standard addition method were used to evaluate the matrix effects. In the determination of iron content of ferrous sulphate tablet and syrup FAAS using external standard give approximately the same results as cerimetric methods of analysis. But in the case of ferroglobin syrup and Fefol capsule the external calibration results had large deviation from cerimetric method of analysis. So flame atomic absorption spectrometric involving standard addition is proposed for the analysis of iron content of these pharmaceutical products. The coefficient of variation for the FAAS determinations were in the range of 0.73-5.85 in one day and 2.39-7.51 between different days. Statistical evaluation showed good correlation between two methods.