Desenvolvimento e avaliação de atividades biológicas de sistemas microemulsionados contendo extratos de Cordia glabrata Mart. A.DC. (Boraginaceae)

Abstract

Extracts of species of the genus Cordia have shown several biological activities such as antioxidant, anti-inflammatory, antiparasitic, antimicrobial and antiviral. Within the genus, there is the species Cordia glabrata (Mart.) A.DC. (Boraginaceae), which has not yet been reported on its phytochemical profile and possible biological activities. The present study aimed to evaluate the phytochemical profile of ethanolic extracts of leaves of the species C. glabrata in different phenophases, and from the characterization of the extracts, to develop microemulsified systems (MEC) to evaluate them against the antioxidant, photoprotective, antimicrobial potential and virucide in vitro. The five MEC developed containing extract showed physical-chemical stability at 25 ± 1 °C, and when submitted to rheological analysis, all presented Newtonian behavior, with particle sizes between 225.74 to 273.33 nm and zeta potential between -22.40 to -25.08. The analysis of the phytochemical profile of the extracts of C. glabrata revealed the presence of flavonoids, tannins and terpenes and among the phenolic acids, caffeic acid, p-cumaric acid and ferulic acid were found, which showed constancy in the concentration even after the incorporation of the extract in the MEC. At the same time, GC/MS analysis (gas chromatography coupled with mass spectrometry) in the extract showed a greater amount of palmitic (51.17%), stearic (20.34%), linoleic (9.62%) and myristic fatty acids (8.16%). In the evaluation of the antioxidant potential determined by the methods of sequestration of the radicals DPPH (2,2-diphenyl-1-picrilhidrazila) and ABTS+ (2,2'-azino-bis (3-ethylbenzothiazolin) 6-sulfonic acid), there was a best activity for extracting leaves in the adult phenological stage with an EC50 of 54.63 µgmL-1 against the DPPH radical and 44.21 mM against ABTS+ , after being incorporated into the MEC they presented an EC50 from 38.13 to 45.54 µgmL-1 for DPPH, and 34.46 to 39.60 mM for ABTS+ . The Sun Protection Factor (SPF) was determined in vitro by a spectrophotometric method, where the extracts of young and adult leaves had an SPF of 5.47 and 5.41 respectively, being considered values close to the minimum SPF required by ANVISA (Brazilian Health Regulatory Agency), and after being incorporated into the MEC, they were between 2.14 to 2.84. No antimicrobial activity was observed for the extract against Staphylococcus aureus, which, during the analyzes, obtained a minimum inhibitory concentration of 2000 μgmL-1 . However, the anti-herpetic evaluation of the extract against the Herpes simplex virus (HSV) type 2 by the lysis plaque reduction assay, showed a potent virucidal activity in the concentrations tested with a CV50 <0.195 μgmL-1 and Selectivity Index (SI=CC50/CV50) greater than 448. To evaluate the virucidal action of the MEC, 2 and 5 MEC were chosen based on the general stability of the system and better hydrodynamic particle diameter which resulted in a CV50 <0.195 µgmL-1 and index of Selectivity greater than 20. The results obtained in this study suggest that C. glabrata leaf extracts in their adult phenological stage have antioxidant, photoprotective and virucidal potential, and when incorporated into microemulsified systems, they maintain their biological actions provenient by the extract.