| Summary: | The roots of most terrestrial plants are colonized by mycorrhizal fungi. Mycorrhizae are symbiotic associations established between certain soil fungi and most vascular plants worldwide. Mycorrhizal symbioses improve the resilience of plant communities against environmental stresses, including nutrient deficiency, in particular increase the roots' ability to better capture nutrients and avoid soil disturbance. The plant produces organic molecules such as sugars by photosynthesis and supplies them to the fungus, and the fungus supplies to the plant water and mineral nutrients, such as phosphorus, taken from the soil. Through mycorrhization, the plant obtains phosphate and other minerals, such as zinc and copper, from the soil. Thus, during this process there is the release of compounds from the secondary metabolism, some of them characterized by their bioactive potential. Phenolic compounds and volatile compounds (secondary metabolites) are some of the molecules released during the oxidative stress process. To better understand the establishment of the mycorrhizal symbiosis and to promote the production of compounds of interest, namely secondary metabolites, the plant Castanea sativa Mill and the mycorrhizal fungi Paxillus involutus (Batsch) Fr. were placed in co- culture for different periods (24h and 48h). The evaluation of phenolic and volatile compounds in both species was evaluated before and after the co-culture, the aim of the present work was to (i) induce the mycorrhizal symbiosis of chestnut tree with compatible fungi in vitro, and (ii) search for phenolic and volatile compounds involved in the mycorrhizal process in vitro, (iii) analyzing the influence of the contact with the host roots on the profile of these compounds. After the co-culture period, the mushroom and the roots of C. sativa were analysed for the presence of phenolic and volatile compounds. The phenolic compounds were assessed by liquid chromatography equipped with a diode-array detector and coupled to a mass detector (LC-DAD-ESI/MSn). The volatile compounds, after extraction by hydrodistillation, will be determined by GC-MS (Gas Chromatography - mass spectrometry). The results obtained, showed the same phenolic compounds in the control roots and in the roots co-cultured with the mycorrhizal fungus (24h and 48h). Regarding the fungus (P. involutus), the identification was very difficult, but one fragments of compounds were present, namely acids (phenylethanol). Wild mushrooms have been pointed as valuable health foods, rich in protein, vitamins and minerals; a source of bioactive compounds, such as unsaturated fatty acids or mono/oligosaccharides; and as having bioactive properties, such as antioxidant, anti- inflammatory, or antimicrobial activities. During the collection of mushrooms for the present work, other than isolation in vitro : the analysis of wild mushrooms ( Lactarius deliciosus , Boletus pinicola 2, Boletus pinicola 3, Tricholoma terreum and Tricholoma equestre) in order to evaluate the antioxidant potential (free radical scavenging effect, reducing power and inhibition of lipid peroxidation), antimicrobial (antibacterial using Gram-positive and Gram-negative strains and antifungal activity) and the absence of toxicity (porcine liver primary cells) of the ethanol/methanol extracts, anti-inflammatory activity, and to contribute with updated information on natural sources of bioactive compounds, thorough chemical characterization and possible applications. The results obtained demonstrated that the extract of all wild mushrooms studied presented antioxidant activity, antimicrobial, cytotoxity activities and contained different classes of various bioactive molecules, besides carbohydrates lipids, proteins, and minerals. For the results of the phenolic compounds, the five mushroom samples presented 2 phenolic compounds protocatechuic acid and p-hydroxybenzoic acid.
|
|---|