Résumé:
In the present work, the aerial parts (1200 g) of the Saharan plant Hammada articulata underwent maceration in 80% ethanol. After filtration, the solution obtained was concentrted (37°C) then added with distilled water (480 mL). After standing overnight at 4°C and filtration, the solution obtained is extracted successively with petroleum ether, chloroform, ethyl acetate and n-butanol. The organic phases were dried with Na2SO4, filtered and concentrated giving the corresponding derived extracts. Phytochemical screening of the CHCl3, AcOEt and n-BuOH extracts revealed their classes of secondary metabolites. Their total contents of phenolic compounds and flavonoids were also evaluated by spectrophotometric methods. The assay results showed the richness of the AcOEt and n-BuOH extracts in polyphenols and flavonoids. The determination of the phenolic composition of several fractions of the three extracts was carried out by HPLC-DAD. We note the presence of phenolic compounds, mainly phenolic acids and flavonoids. GC/FID and GC/MS analysis of Hammada articulata essential oil showed that this oil is dominated by sesquiterpenes as a major class. The main components found in this oil were hexahydrofarnesyl acetone, β-bisabolene and eugenol. In addition, the antioxidant activity of the extracts was evaluated by three methods: DPPH, ABTS and FRAP. The results underline that the AcOEt and n-BuOH extracts showed the best antioxidant capacities, depending on polyphenol and flavonoid contents. Concerning in vivo work, the three extracts of H. articulata were evaluated for their anti-inflammatory activity on a model of edema induced by carrageenan in rats. All extracts showed considerable anti-inflammatory activity, the highest was recorded in the group treated with n-BuOH extract. Regarding diuretic activity, only the CHCl3 extract was active and showed a diuretic spectrum similar to that of hydrochlorothiazide. In addition, AcOEt and n-BuOH extracts of Hammada articulata significantly reduced blood glucose levels in normal rats and rats subjected to temporary hyperglycemia. The second part was devoted to the study of the inhibiting properties of the oil and the extracts of the selected plant against the corrosion of stainless steel in an acid medium using several techniques such as the gravimetric study, the potentiodynamic method and electrochemical impedance spectroscopy. The results showed that these green inhibitors possess relevant inhibitory performance. The adsorption of natural compounds on the steel surface obeys the Langmuir isotherm and is of the physisorption type. Mechanisms of adsorption of these compounds on the surface have been proposed.
