Wild mushrooms and their mycelia as sources of bioactive compounds: antioxidant, anti-inflammatory and cytotoxic properties

Mushrooms are an important source of natural compounds with acknowledged bioactivity. Pleurotus eryngii (DC.) Quél., in particular, is widely recognized for its organoleptic quality and favorable health effects, being commercially produced in great extent. On the other hand, Suillus bellinii (Inzenga) Watling is an ectomycorrhizal symbiont, whose main properties were only reported in a scarce number of publications. Some current trends point toward using the mycelia and the culture media as potential sources of bioactive compounds, in addition to the fruiting bodies. Accordingly, P. eryngii and S. bellinii were studied for their composition in phenolic acids and sterols, antioxidant capacity (scavenging DPPH radicals, reducing power, β-carotene bleaching inhibition and TBARS formation inhibition), anti-inflammatory effect (by down-regulating LPS-stimulated NO in RAW264.7 cells) and anti-proliferative activity (using MCF-7, NCI-H460, HeLa, HepG2 and PLP2 cell lines). Overall, S. bellinii mycelia showed higher contents of ergosterol and phenolic compounds (which were also detected in higher quantity in its fruiting body) and stronger antioxidant activity than P. eryngii. On the other hand, P. eryngii mycelia showed anti-inflammatory (absent in S. bellinii mycelia) and a cytotoxicity similar (sometimes superior) to its fruiting bodies, in opposition to S. bellinii, whose mycelia presented a decreased anti-proliferative activity. Furthermore, the assayed species showed differences in the growth rate and yielded biomass of their mycelia, which should also be considered in further applications.

The impact of gamma irradiation on the cytotoxic properties and phenolic composition of Thymus vulgaris L. and Menta x piperita L.

Irradiation has been increasingly recognized as an effective decontamination technique, also ensuring the chemical and organoleptic quality of medicinal and aromatic plants 1 . The use of medicinal plants in the prevention and or treatment of several diseases has revealed satisfactory results as anti-inflammatory, antimutagenic, anti-cancer and antioxidant agents 2 . The aim of the present study was to evaluate the effects of gamma irradiation on the cytotoxic properties and phenolic composition of Thymus vulgaris L. and Menta x piperita L. (methanolic extracts). Phenolic compounds were analyzed by HPLC-DAD-ESI MS, while the cytotoxicity of the samples was assessed in MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer), HeLa (cervical carcinoma), HepG2 (hepatocellular carcinoma) cell lines, as also in non-tumor cells (PLP2). Thirteen and fourteen phenolic compounds were detected in T. vulgaris and M. piperita, respectively, but none of them was affected by the irradiation up to a dose of 10 kGy. However, despite there were no changes in the cytotoxic properties of irradiated peppermint samples in tumor cell lines, the thyme samples irradiated with 10 kGy showed higher cytotoxicity in comparison with the samples submitted to other doses (2 and 5 kGy). This highlights that 10 kGy can be a suitable dose to ensure the sanitary treatment, without modifying the bioactive composition and properties of these aromatic plants.