Etnobotânica, composição química e atividades biológicas de espécies medicinais do gênero Psidium L. (Myrtaceae Juss.)

Abstract

Medicinal species of the genus Psidium L. (Myrtaceae Juss.) have a long history of use in folk medicine to cure or treat a variety of symptoms. The presence of essential oils can explain the multiple biological activities, such as antimicrobial and antioxidant. This study aimed to survey the medicinal uses of native species of Psidium and analyze the chemical composition and biological activities. This work had two phases in the 1st, a systematic review of scientific articles was carried out that linked the terms ethnobotany of medicinal plants, chemical composition, and pharmacological tests, for the genus, using 25 terms in the searches. The publications went through inclusion and exclusion criteria, such as year, language, the full name of the species, databases, type of publication. The research generated a total of 4.202 records, which, after passing through the established filters, 70 articles were analyzed. This analysis allowed the identification of 13 native species of Psidium, of which six were mentioned in folk medicine, with the main indication within the digestive system. Of the total number of species, 12 showed an investigation of chemical composition and/or biological activity, and their chemical compounds were identified as responsible for the activities suggested. In the 2nd phase, chemical analysis and antibacterial, modulating, and antioxidant activity of the medicinal species Psidium laruotteanum Cambess., Psidium salutare (Kunth) O. Berg and Psidium sobralianum Landrum & Proença were performed. The species were collected in two areas of Cerrado disjoint from Chapada do Araripe (Brazil). The extraction of essential oils from the leaves was carried out by hydrodistillation and identified by gas chromatography coupled to mass spectrometry (GC/MS). Antibacterial activity was evaluated by the serial microdilution method, determining the minimum inhibitory concentration (MIC) and modulating activity. In the bacterial assay, Escherichia coli Ec 27, Pseudomonas aeruginosa ATCC 15442, Staphylococcus aureus Sa 358, and Streptococcus mutans INCQS 00446 were used. The essential oil of P. laruotteanum was evaluated for its modulatory effect against the antibiotics amikacin and cephalothin. The DPPH method (1,1-diphenyl-2-picrylhdrazine) was used to evaluate the antioxidant activity. The results were analyzed by ANOVA and the Tukey and Bonferroni test. A total of 26 compounds were identified for the species. These were demonstrated to be chemically different, not presenting any compound common to the three species. Among the major ones, 1.8-cineole (57.07%), α-phellandrene (14.62%) (P. salutare); Viridiflorol (27.89%), α-caryophyllene (27.62%) (P. laruotteanum); Viridiflorol (11.64%) and α-pinene (11.78%) (P. sobralianum). The essential oil of P. laruotteanum inhibited the growth of E. coli at a concentration of 96 μg/mL, and showed a synergistic effect when associated with amikacin on S. aureus, with p<0.001. Psidium salutare and P. sobralianum inhibited bacterial growth at higher concentrations, between 341.33 μg/mL and ≥ 1024 μg/mL, with little clinical relevance. In relation to antioxidant activity, the results were concentration-dependent, with the best result for P. sobralianum oil with IC50 of 5.99 mg/mL, when compared to controls Ascorbic Acid IC50 0.02 mg/mL and Eugenol IC50 0.04 mg/mL.