عنوان مقاله [English]
Aspergillus flavus mold causes many contaminants in foodstuffs with aflatoxin production. Today, many researches are carried out for the use of natural compounds especially herbal essential oils for inhibiting production of fungi toxins. In this study, the effect of Artemisia essential oil on strains (R5 and P7) of Aspergillus flavus was investigated. In the experiments 13 different concentrations (4.5, 9, 13.5, 18, 36, 72, 86, 100, 114, 128, 142, 166 and 180 µL/L) Artemisia essential oil was added to PDA culture medium and then with separately culture of strains of Aspergillus flavus, inhibition rate of essential oil investigated in growth of strains. In investigation of diameter size of the grown halos in compared to control, it was observed that diameter of halos had been decreased with increasing essential oil concentration. So that in strains R5 (halo diameter 18.97 mm) and P7 (halo diameter 18.39 mm) with essential oil concentration of 166 µL/L, the most inhibitory effect had in compared with control sample.
Research on different species of Artemisia has shown the presence of lactones, terpenes and flavonoids in essential oils. These species are known for their bioactive compounds, which are mainly terpenoids and phenolic compounds. Fungi are important factors in food spoilage during storage, which reduces the quality and quantity of products and as well as due to high ability to produce a variety of mycotoxins that cause great risks for consumers. In particular, some strains of Aspergillus flavus and Aspergillus parasiticus have shown toxic, carcinogenic, mutagenic, and fetal harm effects in humans and animals by producing different types of mycotoxins. Fungal control is usually done using chemicals, but these substances often have side effects such as carcinogenesis in the consumers. Therefore, in recent years a lot of studies have been carried out on natural compounds, especially plant essential oils to inhibit the growth of fungi and aflatoxin production.
Aerial parts of A. frariris Willd plant collected from aznab area of horand city. About 200 gr plant was used for extracting essential oil with aclevenger Apparatus within 2.5 hours. GC-MS analysis of essential oil was performed for identifying and quantifying of compounds. The C8-C20 alkanes were analyzed under the same conditions in GC-MS analysis to calculate the retention index (RI) of the compounds. For preparing 12 different levels (4/5, 9, 13/5, 18, 36, 72, 86, 100, 114, 128, 142, 166 and 180 µL/L), equal concentrations of Artemisia essential oil mixed with dimethyl sulfoxide (as a solvent). These operations were performed for both strains separately in three replications. After inoculating R5 and P7 strains with diameter of 2 mm on culture medium, all petri dishes were incubated at 27 ̊C for 7 days. The experiments were performed in three replications in a completely randomized design. Data were analyzed by analysis of variance at the probability level of p Conclusion
Analysis of Artemisia essential oil by GC-MS showed that was about 32 different types of compounds. The percentage of main constituents showed that oxygenated monoterpenes (72.2% frequency), tojun (41.19% frequency), 1,8-Sineol (23.79% frequency) and Camphor (4.66% frequency) were in essential oil. In general, Artemisia essential oil contains of 94.43% of monoterpenes which antifungal activity of essential oil was attributed to these components. In the case of R5 strain, increasing the essential oil concentration up to 36 µL/L had no effect on halo diameter at compared to control (halo diameter of 67.4 mm). But, the concentration of 72 µL/L and higher had significant effects on reducing diameter of strain halo, which the lowest halo diameter (18.39 mm) was obtained at 166µL/L (p < 0.05). In P7 strain, increasing essential oil concentration up to 13.2 µL/L (halo diameter of 69.17 mm) had no effect on the halo diameter at compared to control. But, the concentration of 18µL/L and higher had significant effects on reducing diameter of strain halo that the highest reduction (18.97 mm halo diameter) obtained in 166 µL/L (p < 0.05). Plant essential oils contain of compounds with different bioactive effects such as antimicrobial properties. Many metabolites protect the plant against pests and diseases. Studies have shown that the amount and even the type of these metabolites in a plant type depend on the environmental and geographical conditions of their growth. Common phytochemicals include phenols, flavonoids, coumarins, cinnamic acid and other derivatives. Tojun with 41.19% abundance is an important ingredient in Artemisia essential oil. The study of its mechanism role as antifungal has shown various antifungal pathways such as 1) damage to DNA, 2) dysfunction of ribosomes, 3) oxidation of proteins, 4) destruction of cell wall and membrane, 4) disruption of electron transfer process and 5) Inhibition of cell secretion to the environment outside.
The research of Sardroodian and Arianfar (2015) was performed to identify the phytochemical compounds, antioxidants and antimicrobials of A. Turanica essential oil. In the analysis of essential oils, 26 different compounds, mainly oxygen monoterpene, were identified. The 4 major constituents of this essential oil were chrysanthanmene (21/37%), 1,8-cineole (19/20%), piperitenene (16/61%), alpha-pinene (52/5%) and tojun (14/12%). The study of antimicrobial properties showed that the inhibition of gram-negative bacteria by essential oil from plant shoots was more than gram-positive types. Also, the antibacterial properties of the essential oil of this plant were comparable to gentamicin. It was concluded that large amounts of phenolic and terpene compounds of A. Turanica essential oil had high antioxidant and antimicrobial effects, which could recommend as a valuable subject for further research.
The results showed that Artemisia essential oil was very effective in controlling the growth of strains of Aspergillus flavus (R5 and P7) compared to the control sample. So that in higher concentrations, it was able to inhibit significantly the growth of Aspergillus strains with monitoring halo diameter. Important constituents of Artemisia essential oil include tojun and carvacrol, which inhibited strains of Aspergillus flaus by damaging to DNA, electron chains, cell wall and membrane, as well as increasing cell leakage to outside.
Artemisia essential oil, Aspergillus flavus, Antimold role, Halo diameter.