Control of Aspergillus section Flavi growth and aflatoxin accumulation by plant essential oils.

AIMS: The antifungal effect of Pimpinella anisum (anise), Pëumus boldus (boldus), Mentha piperita (peppermint), Origanum vulgare (oregano) and Minthosthachys verticillata (peperina) essential oils against Aspergillus section Flavi (two isolates of Aspergillus parasiticus and two isolates of Aspergillus flavus) was evaluated in maize meal extract agar at 0.982 and 0.955 water activities, at 25 degrees C. METHODS AND RESULTS: The percentage of germination, germ-tube elongation rate, growth rate and aflatoxin B(1) (AFB(1)) accumulation at different essential oils concentrations were evaluated. Anise and boldus essential oils were the most inhibitory at 500 mg kg(-1) to all growth parameters of the fungus. These essential oils inhibited the percentage of germination, germ-tube elongation rate and fungal growth. AFB(1) accumulation was completely inhibited by anise, boldus and oregano essential oils. Peperina and peppermint essential oils inhibited AFB(1) production by 85-90% in all concentrations assayed. CONCLUSIONS: Anise and boldus essential oils could be considered as effective fungitoxicans for Aspergillus section flavi. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results suggest that these phytochemical compounds could be used alone or in conjunction with other substances to control the presence of aflatoxigenic fungi in stored maize.

Screening of Argentine plant extracts: impact on growth parameters and aflatoxin B1 accumulation by Aspergillus section Flavi.

The effect of essential oils, ethanolic and aqueous extract of 41 vegetable species on Aspergillus section Flavi growth was evaluated. The in vitro screen was a two-stage process. A wide-spectrum initial screen which identified promising antifungal plant extracts was carried out first. After that, identified extracts were studied in more detail by in vitro assays. A total of 96 plant extracts were screened. Essential oils were found to be the most effective extract controlling aflatoxigenic strains. Clove, mountain thyme, poleo and eucalyptus essential oils were selected to study their antifungal effect. Studies on percentage of germination, germ-tube elongation rate, growth rate, and aflatoxin B1 accumulation were carried out. Clove, mountain thyme and poleo essential oils showed the most antifungal effect under all growth parameters analyzed as well as aflatoxin B1 accumulation. Our results suggest that mountain thyme and poleo, which are native vegetal species of Argentina, and clove essential oils could be used alone or in conjunction with other substances to control the presence of aflatoxigenic fungi in stored maize.

[Changes in serotonin and histamine levels in human blood after 370-day anti-orthostatic hypokinesia]. / Izmenenie soderzhaniia serotonina i gistamina v krovi cheloveka pod vliianiem 370-sutochnoi antiortostaticheskoi gipokinezii.

Ten healthy men took part in a 360-day antiorthostatic hypokinesia study. They were subdivided into two equal groups that differed in terms of time when they started using counter-measures: Group A began exercising on the first day of exposure and Group B on bed rest day 120. As compared to the baseline, the test subjects showed a decrease of serotonin (Ser) and histamine (HA). The only exception was HA increase on bed rest day 50 in the Group A subjects. The difference in Ser and HA concentrations in Group A and B subjects was insignificant on bed rest days 110 through 350. On the 60th day after the study Ser and HA concentrations did not yet return to norm. These observations indicate that changes in the serotonin- and histaminergic systems cannot be compensated within the above period of time.

[Use of erythrocytes for the intravital evaluation of adrenoreceptor function]. / Ispol'zovanie éritrotsitov krovi dlia prizhiznennoi otsenki funktsional'nogo sostoianiia adrenoretseptorov.

Administration of guanethidine (50 mg/kg) decreased the noradrenaline content in adrenergic neurons which led to an augmentation of the effector organ's adrenoreactivity in rats. The affinity of the erythrocytes' beta-adrenoreceptors to propranolol was enhanced and the parameters of their binding the fluorescent probe were changed. The data obtained suggest the possibility of using the erythrocytes for in vivo estimation of functional state of adrenoreactive system in animals and humans.

[Study of the beta-adrenoreceptive function of the erythrocyte membrane of the guinea pig using spectral luminescence analysis]. / Issledovanie beta-adrenoretseptivnoi funktsii membran éritrotsitov morskoi svinki s pomoshch'iu spektral'nogo liuminestsentnogo analiza.

The binding of DSM fluorescent probe with erythrocyte membranes in conditions of the organism high and low adrenoreactivity was studied in guinea pig. The dependence of DSM binding on the level of adrenoreactivity was shown by probe luminescence in the range of 615 nm. Specific and unspecific types of the DSM bindings with erythrocyte membranes were revealed. In high adrenoreactivity, an increase of specific binding places (Nsp) and a decrease of specific binding constant (Ksp) were found whereas in low adrenoreactivity the Nsp decreased and the Ksp increased.

[The use of fluorescence probes in the study of the beta-adrenoreceptor function of human erythrocytes]. / Primenenie fluorestsentnogo zonda dlia izucheniia beta-adrenoretseptivnoi funktsii éritrotsitov krovi cheloveka.

Possibility of making use of fluorescent probe 4-(p-dimethyl aminostyril)-1-methyl pyridinium p-toluene-sulphonate (DSM) for observing the interaction of beta-adrenoactive substances (adrenaline and propranolole) and specific receptors of human blood erythrocytes has been studied. Two types of DSM bindings with erythrocyte membranes have been revealed--specific and non-specific. It has been found that DSM reacts selectively to preliminary influence of beta-adrenoactive substances: antagonist propranolole diminishes both specific and nonspecific bindings and agonist adrenaline increases specific binding with the membrane erythrocytes. The conclusion is made as to possible use of DSM probe for investigating beta-adrenoreceptive function of the cell membranes.

[Fluorescent method of determining serotonin deaminating monoamine oxidase activity based on the amount of 5-hydroxyindoleacetic acid]. / Fluorestsentnyi metod opredeleniia serotonindezaminiruiushchei aktivnosti monoaminoksidazy po kolichestvu 5-oksiindoluksusnoi kisloty.

A fluorimetric procedure is developed for estimation of serotonin deaminating activity of MAO by measuring the oxidized reaction product-5-hydroxyindolyl acetic acid (5-HIAA) extracted from acid solution by means of diethyl ester with subsequent transfer in 0.1 M phosphate buffer, pH 7.3. The optimal conditions for the extraction were developed, ensuring the maximal yield of 5-HIAA and serotonin. Low content of serotonin was found in the phosphate buffer. The concentration of serotonin was similar both in test and control samples; it did not interfere with the estimation of 5-HIAA. Sensitivity and reproducibility of 5-HIAA estimation by means of its fluorescence in 3 N HCI was higher as compared with the reaction with o-phthalic dialdehyde. Yield of 5-HIAA extracted from solution was approximately 90%. Activity of MAO, as shown by reaction of 5-HIAA with o-phthalic dialdehyde, was equal to 2.81 +/- 0.19 nM/mg/min (n = 15) and - by fluorescence in 3 N HCL - 2.92 +/- 0.29 nM/mg/min (n = 12).