João Pedro Mesquita Oliveira Knihy

P. guajava leaves and essential oil obtained by hydrodistillation technique were collected. Chemical constituents were evaluated by gas chromatography-mass spectrometry (GC/MS). The total phenolic content was quantified by the Folin-Ciocalteau spectrophotometric method. For the toxicity test, the Artemia salina bioassay was applied. The nanoemulsion (W/A) was prepared using the low energy phase inversion method. The LC50 was calculated for the action of the nanoemulsion against Aedes aegypti larvae by the Probit method. The main chemical constituent found in the essential oil of P. guajava was -pinene 34.25%. Total phenolic compounds were quantified as 210.35 mg EAT g-1. In the toxicity bioassay, the LC50 of 323.6 mg L-1 was classified as non-toxic. The nanoemulsion droplets after 30 days of handling had an average size of 120.41 ± 0.55 nm. The larvicidal activity of the nanoemulsion showed mortality at concentrations of 10 to 100 mg L-1 with an LC50 of 12.75 mg L-1.

The study explores the synthesis of silver nanoparticles (AgNPs) from Piper nigrum essential oil nanoemulsion, utilizing a phase inversion method and AgNO3 reduction. It highlights the chemical profile, with limonene as the primary component, and evaluates the antioxidant and anti-inflammatory activities of the AgNPs. Notably, the research found an IC50 value of 16.26 mg L-1 for antioxidant activity and 0.217 mg mL-1 for anti-inflammatory effects at pH 11, demonstrating the efficacy of P. nigrum AgNPs in enhancing these biological activities.