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Corrosive processes in acidic medium reduce the performance and durability of metallic materials, causing problems to several industries. Corrosion inhibitors are commonly used to decrease these effects. As these inhibitors must be ecologically friendly currently, this work evaluated the anticorrosive effect of natural extracts of coffee husks (Coffea arabica L.) in the protection of carbon steel in 1 mol L-1 HCl solution. Extractions were performed using water as the extraction solvent. The polyphenols content increased with the extraction temperature, and the extracts were produced using 100 ºC. Extract concentrations of 10, 20 and 30 % v/v were analyzed as inhibitors for carbon steel in acid medium, using weight loss and electrochemical tests, as well as scanning electron microscopy. There was an increase in the inhibition efficiency as the extract concentration increased, reaching values around 97 % using 30 %v/v of extract for the weight loss tests.

In this study, leaves and flowers of Atractylis babelii were chosen to investigate their antioxidant activities. Thus, a comparison between the antioxidant properties of ethanolic crude extracts obtained by two extraction methods, maceration and soxhlet extraction, was performed using two different tests; DPPH and ABTS radical assays. Besides, total polyphenol, flavonoid and condensed tannin contents were determined in leaves and flowers of Atractylis babelii by colorimetric methods. The results showed that there was no correlation between phenolic contents of plant parts and their antioxidant activity. Whereas, leaves and flowers of Atractylis babelii showed that both had almost similar phenolic contents, while their antioxidant activity depended on the plant parts. Furthermore, the antioxidant activity of plant parts was also depended on extraction method. Such a result may be likely ascribed to a variety of chemical composition can be found in Atractylis babelii extracts which has been related to its antioxidant properties.