Antibacterial and insecticide activities of the Persea americana Mill seeds

Abstract: In recent decades, resistance to antimicrobials has increased, mainly associated with to overconsumption and the propagation of vectors that transmit microorganisms. In this sense, plant-derived extracts with novel mechanisms of actions are in the focus of several researches. Persea americana Mill is a tree with several known biomedical applications, but pharmacological potential still need to be fully investigated. The current study explores new approaches in the antibacterial activity of ethanolic extracts of P. americana var. americana seeds obtained by the Soxhlet (SE) and Maceration (MaE) methods; being evaluated from the anti-adhesive effects, antibiofilms and the action against the vectors that transmit microorganisms. Soxhlet methodology was statistically more efficient in the extraction of metabolites with a total solid value of 42.13 \ub1 1.76 mg/mL compared with MaE (20.46 \ub1 1.66 mg/mL). Additionally, SE showed a higher amount of polyphenols (5.12 \ub1 0.18 mg/mL). The phytochemical screening and the UHPLC-DAD-QTOF analysis also showed the presence of polyphenols and neolignan as main compounds identified. The influence on the post- embryonic development of Musca domestica was demonstrated, especially on the viability of larvae stage. The adulticidal effects of the extracts were determined by LC50 of 2.910 mg/100 mL and 3.944 mg/100 mL for MaE and SE extracts, respectively. Additionally, both extracts showed larvicidal and pupicidal effects against Aedes aegypti, but SE were more active at lower concentrations. Extracts showed antibacterial activity against Pseudomonas aeruginosa (IC50= 87 and 187 g/mL) and Staphylococcus aureus (IC50= 144 and 159 g/mL). SE and MaE extracts were also able to significantly reduce the bacterial adhesion to A549 lung epithelial cells. Additionally, both extracts inhibited the biofilm growth and facilitated the release of internal cell components in P. aeruginosa, which might be associated with cell membrane destabilization. Real-time PCR and agarose electrophoresis analysis indicated that avocado seed ethanol extracts (64 g/mL) downregulated virulence-related factors such as mexT and lasA genes. Moreover, no significant toxic effects on monocytes, microglia cells and fibroblast human cells were found after treatment (CC50> 500 \u3bcg/mL). The results of this research provide potential value to the reuse of a P. americana Mill var. americana seeds as alternatives to the vector control, thus avoiding microorganisms spreading, and also novelty treatment of infectious diseases. In this sense, bioproducts from avocado seeds can be considered promising anti- adhesive and anti-biofilm agents