Evaluación de la actividad antimicrobiana del aceite esencial de membrillo (GUSTAVIA ANGUSTIFOLIA) mediante la técnica de Microdilución para su aprovechamiento biotecnológico

Abstract

This research evaluated the chemical composition and antimicrobial activity of the essential oil and leaf extracts of Gustavia angustifolia, a little-studied species of the Ecuadorian coast, to determine its potential biotechnological applications. Plant material was collected in the Bosque Protector Prosperina during the rainy season. The essential oil was obtained by hydrodistillation using a Clevenger apparatus, while the extracts (alcoholic, hydroalcoholic, and aqueous) were obtained by ultrasound-assisted maceration. Chemical characterization by gas chromatography-mass spectrometry (GCMS) revealed a predominantly sesquiterpene profile, with Caryophyllene <(Z)-> identified as the major compound, along with significant amounts of Nonane and Pinene. Phytochemical screening of the extracts (aqueous, hydroalcoholic, and alcoholic) revealed the presence of complementary groups such as alkaloids, phenols, saponins, terpenoids, coumarins, and sesquiterpene lactones, with the alcoholic extract exhibiting the highest metabolite availability. Antimicrobial activity was evaluated using the broth microdilution technique against Escherichia coli and Candida albicans. The results demonstrated marked selectivity of the essential oil towards the Gram-negative bacteria, achieving 69.54% inhibition at a concentration of 5% v/v (IC50 < 5%), surpassing thefungistatic activity observed against the yeast (46.89% inhibition; IC50 ≈ 5%). Although an absolute Minimum Inhibitory Concentration (MIC) (< 5%) comparable to positive controls was not determined, the oil's ability to significantly reduce the microbial load suggests its viability as a bacteriostatic agent in disinfectant formulations or natural preservatives, adding value to the local bioeconomy.