Etude phytochimique et pharmacologique de deux plantes sahariennes

Abstract

This work is devoted to the phytochemical, biological and pharmacological study of two endemic Saharan species; Helianthemum lippii (Cistaceae) and Cymbopogon schoenanthus (Poaceae). The extraction of the two species followed by the chromatographic separations (CC, CCM and HPLC semi-preparative), led to isolate and identify using spectroscopic methods (1D and 2D NMR) 6 compounds among which two sterols, as well as four sesquiterpenes: Stigmasterol, β- Sitosterol, (1S,4aa)-4Methylene-6-(1-hydroxy-&-methyethyl)-8a-b-methyl-decahydroxydronaphtalene-Ab-ol 1S, 7S, 10S, eudesm-4(14)-en-1α-11α-diol(hydroxy-β-eudesmol), 4α, 11-dihydroxy-7-epimereudesmandiol (7-epi-cryptomeridiol), 4β, 7β, 11-enantioeudesmantriol (Pterodontriol), 4β,6β,10α-trihydroxy guaiane sesquiterpène (Teuclatriol). Chromatographic analysis of the essential oils of Cymbopogon schoenanthus showed that the hydrocarbons represented 26.7% while the sesquiterpene fraction reached 40%. The HPLC-TOF / MS analysis of the AcOEt and n-BuOH extracts of the two species suggested the presence of 32 phenolic acids and flavonoids which were present in different proportions The efficacy of inhibiting DNA damage and the evaluation of the anticancer activity carried out on the EtOAc and n-BuOH extracts of the two species demonstrated a particularity observed in Helianthemum lippii on the antioxidant effect and thus the antiproliferative effect. The pharmacological study was carried out on the effect of the extracts on the distal colon of Wistar rats; which have shown a marked relaxing effect on the isolated distal colon of the rat which could represent an underlying mechanism for the traditional use of these plants for gastrointestinal conditions. Further studies will help us understand the metabolites responsible for the effect and mechanism involved.