Currently, oxidative stress is one of the major problems that threatens human health. It is at the root of many diseases such as cancer. Despite the enormous efforts provided to combat this scourge, oxidative stress is still relevant and hence comes the need for research of new remedies especially from natural origin. For this purpose, the study of the antioxidant activity of extracts of Cistus monspeliensis from Morocco is a principal research objective. The phenolic extracts were obtained by maceration of the plant in a water/acetone mixture and then separated by liquid/liquid extraction with solvents of increasing polarity. The first phytochemical tests carried out on these extracts showed the existence of different families of phenolic compounds, such as flavonoids, tannins, and others. Assays for total polyphenols, flavonoids, hydrolysable, and condensed tannins were carried out by known colorimetric methods. The results of these assays have shown that the studied extracts are rich in phenolic compounds present in the plant in the form of flavonoids (69.81 ± 0.22 mg EQ/g DM), hydrolysable tannins (61.86 ± 0.89 mg ETA/g DM), and condensed tannins (70.05 ± 1.61 mg EC/g DM). The evaluation of the antioxidant activity is carried out by two different methods: the DPPH test (2,2-DiPhenyl-1-Picryl-Hydrazyl) and the FRAP test (Ferric Reducing Antioxidant Power). The results obtained show that the extracts of Cistus monspeliensis are active and have interesting antioxidant powers. In particular, the water/acetone (WAE) (IC50 = 0.079 mg/mL) and butanolic (BUE) (IC0.5 = 0.099 mg/mL) extracts are the most active with values comparable to that of ascorbic acid. The interesting results obtained in this study clearly show that Cistus monspeliensis originating from Morocco can be considered as a source of natural antioxidants. Therefore, the extracts of this plant deserve to be tested in the medicinal field, against cancer and cardiovascular diseases, and in food field as an additive and preservative.

The aim of this study is the valorization of the Cistus monspeliensis plant, native to North of Morocco, as antioxidant and corrosion inhibitor. Firstly, the plant is extracted by maceration in a mixture of water/acetone solvents. Phytochemical tests are carried out on the extract obtained. The antioxidant power of Cistus monspeliensis extract is evaluated by two methods: the test of reduction of the free radical DPPH∙ (1,1-diphenyl-2-picryl hydrazyl) and that of Ferric reducing antioxidant power (FRAP). The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization are used to study the anticorrosion effect of Cistus monspeliensis extract. The results showed that the extract, 27.6% yield, contains phenolic compounds in the form of flavonoids, hydrolysable and condensed tannins, saponins, reducing sugars and glycosides. This extract has an antioxidant capacity similar to that of ascorbic acid with an inhibition concentration of 0.077 mg/mL 0.102 mg/mL for DPPH and FRAP test, respectively. Tafel plots show that the extract is an excellent cathodic inhibitor. The maximum inhibition efficiency of 92 % was obtained with 0.25 g/L of the inhibitor at 298 k. The impedance plot is characterized by a single capacitive loop attributed to the charge transfer process. The results also showed that the inhibitor acts on the surface of the metal principally by adsorption, leading to the formation of a protective film limiting the corrosion of ordinary steel.