Abstract

Simira gardneriana is a Rubiaceae species commonly found in the Brazilian Northeast region, presented several therapeutic and biotechnological applications. In this paper, the antioxidant and photoprotective properties of extracts from the seeds of S. gardneriana were highlighted. The antioxidant activity of ethanol and methanol extracts (Si-EtOH and Si-MeOH, respectively) was determined, using 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay. The photoprotective activity of the extracts was evaluated using a spectrophotometric method. Total phenolic and flavonoid content was determined. In addition, a qualitative analysis of phytochemical markers and a high-performance liquid chromatography-diode-array detector (HPLC-DAD) analysis were also performed for both extracts. Concerning the antioxidant activity in vitro, Si-MeOH (EC₅₀ = 70.94±2.17 µg/ml) showed greater activity in comparison to Si-EtOH (EC₅₀ = 138.60±7.39 µg/ml). Once the sun protection factor spectrophotometric (SPF_{spectrophotometric}) of samples was calculated, it was demonstrated that the extracts show a similar photoprotective effect on all concentrations tested. Si-EtOH and Si-MeOH tested on a concentration of 100 mg/l, exhibited SPF values equal to 3.37±0.006 and 3.36±0.007, respectively. HPLC fingerprints was recorded and showed the presence of characteristic peaks for phenolic compounds. The extracts showed significant phenols and flavonoids content according to the quantification methods used. According to the results, it was concluded that Si-EtOH and Si-MeOH have significant antioxidant and photoprotective activities. These activities are probably related to the profile of flavonoids and phenolic compounds found in this species.

Key words: Phenolic and flavonoids compounds, photoprotective, oxidative stress, plant, Rubiaceae.