6533b86ffe1ef96bd12ce3ae

RESEARCH PRODUCT

Highlighting the divertsity of cactus populations (Opuntia spp.) in Morocco and modulation of lipid metabolism by natural extracts and phytosterols from cactus and Argan oil in microglial cells BV2

subject

description

The objective of this PhD thesis is to characterize the Moroccan germplasm of the cactus Opuntia collected from different regions in Morocco, by studying the phenologic behavior, the genetic features and physicochemical composition, along with the molecules of high therapeutic potential which may have beneficial effects on the central nervous system cells from cactus extracts (fruit, flower, seed, oil, cladodes and spine) and compared to Argan oil. This work has been conducted in fours different laboratories sharing complementary analyses skills at agronomic, biochemistry, molecular levels. Our results are presented in three parts : (i) cactus agronomic characteristics, (ii) purification and characterization of natural extracts and molecules and (iii) the evalution of biological effects of these molecules using a cell model. Initially, the first experimental INRA site of cactus culture, located in Ain Nezagh and containing ecotypes older than 4 years, allowed us to achieve a phenological study with the classification of the ecotypes according to fruiting rate and to the biomass production in order to better guide their use according to geographical origin and species. The genetic diversity study based on morphological traits and molecular markers permited the identification, on the site of Ain Nezagh, of the presence of seven species of cactus among which two have never been described in Morocco: O. leucotricha and O. inermis. The morpho-anatomical and physicochemical analyses of cactus flower, juice, fruit and cladodes of 10 years old ecotypes issued from the Jemâat Riah INRA site, demonstrated the presence of two different species of the genus Opuntia including four varieties not previously identified on this site. Thus, our work indicates the existence of a large intra-species (varieties) and inter-species genetic diversity. Secondly, the chemical compositions of cladode essential oils or cactus seeds as well as argan oil were determined. From these analyzes, we have chosen to study the effects of two sterols, spinasterol and schottenol and also sterol extracts on the activation of the nuclear receptor LXR (Liver X receptor, involved in the regulation of cholesterol metabolism) in microglia brain cells (BV-2 murine cell line). Our results show that spinasterol and schottenol, without being cytotoxics, can modulate the expression of the two isoforms of LXR, LXR-α and LXR-β, as well as of their target genes ABCA1 and ABCG1. In addition, the schottenol causes LXR-β specific activation. These results suggest that these two phytosterols could have a protective role in the modulation of cholesterol metabolism in microglia.