Potential of Essential Oil from Siparuna guianensis A. DC. (Siparunaceae) as an Antimicrobial Adjuvant in Topical Formulations

Essential oils have enormous versatility as sources of natural fragrances and as active agents in the cosmetic industry. Therefore, the chemical composition and antimicrobial and antioxidant activities of the essential oil from the fresh leaves of Siparuna guianensis A. DC. for cosmetic purposes were analyzed. The GC/MS technique was used to analyze the essential oil and the major constituents found were the sesquiterpenes bicyclogermacrene (32.52%), germacrene D (21.60%), and germacrene B (6.84%) and the monoterpene myrcene (3.66%). The antioxidant activity of the essential oil was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical sequestering method and the assay based on the oxidation of 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS). The antioxidant potential of the essential oil was not evidenced in both tests. In vitro tests showed that the studied essential oil, when combined with the antibiotic ampicillin, demonstrated a synergistic effect against clinically resistant Staphylococcus aureus and XDR S. epidermidis strains and an additive effect against S. pseudointermedius and MDR S. epidermidis. On the other hand, the combination of essential oil with gentamicin resulted in synergism when tested against S. epidermidis and an additive effect when evaluated against XDR S. epidermidis. Topical products formulated on the basis of these results exhibited activity against resistant S. epidermidis, demonstrating that the essential oil can act as a valuable ingredient to restore the efficacy of antibiotics against multidrug-resistant bacteria, in addition to improving the olfactory characteristics of the final product.