Comparative analysis of chemical profiles and antioxidant activities of essential oils obtained from species of Lippia L. by chemometrics.

Due to the importance of diseases associated with oxidative stress, the search for natural antioxidants proves to be essential. This work aimed to compare the chemical composition and antioxidant potential of essential oils from the genus Lippia L. through chemometric analysis. The essential oils were characterized by gas chromatography coupled with mass spectrometry. Antioxidant potentials were determined by DPPH, ABTS, Deoxyribose and ß-carotene protection, Iron chelation and reduction methods. All data were related by multivariate analyzes. Essential oils showed low similar chemical compositions and no statistically significant relationship. These showed relevant antioxidant activity, especially for L. sidoides that obtained IC50 of 5.22 ± 0.08 µg/mL in ABTS capture. Multivariate analyzes showed the effectiveness of L. alba compounds to DPPH scavenging, Fe3+ reduction and ß-carotene protection, and L. gracilis components to deoxyribose protect. Thus, studies proving the antioxidant potential of Lippia compounds against oxidative stress and their use in food conservation are fundamental.

Influence of seasonal variation on phenolic content and in vitro antioxidant activity of Secondatia floribunda A. DC. (Apocynaceae).

This study reports the effects of seasonal variation on the total polyphenol and flavonoid content and the in vitro antioxidant activity of Secondatia floribunda A. DC. The extracts were prepared from the inner bark and heartwood of samples harvested in the 2015 to 2016. The total phenolic and flavonoid content was determined by specific qualitative tests. The in vitro antioxidant capacity was analyzed using the following tests: 1-1-diphenyl-2-picrylhydrazyl radical (DPPH), 2,2'-azinobis-3-ethylbenzenothiazoline-6-sulfonic acid (ABTS+), ferric reducing antioxidant power (FRAP) and iron (Fe2+) chelating activity. The total polyphenol and total flavonoid content varied over the harvest period. The DPPH and ABTS tests revealed that in the dry season had the most potent in vitro antioxidant activity, although the extracts obtained during the rainy season presented the higher Fe2+ chelating and Ferric reducing activities. In conclusion, the phenolic content and in vitro antioxidant activity are correlated, and both are influenced by seasonality.