Antimicrobial potential in different ontogenetic stages of native plant species

• Grant number: 25/11959-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2025
• End date: July 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Organic Chemistry
• Principal Investigator: Massuo Jorge Kato
• Grantee: Larissa dos Santos Nascimento da Silva
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The growing resistance of fungi and bacteria to drugs represents a serious threaten to global public health, making it urgent to obtain novel bioactive compounds with pharmacological properties. The species Piper cernuum, Varronia curassavica (syn. Cordia verbenaceae) and Protium heptaphyllum (breu, amescla) are widely known for the microbial activity of their secondary metabolites. This study aims to investigate the chemical variability of these species throughout their ontogeny, based on the hypothesis that seedlings which have a different chemical composition from adult plants have better fitness being able to escape pathogens and herbivores. Therefore, while the chemical profiles of seedlings and adult individuals will be evaluated by spectrometric and spectroscopic methods, the assays of antimicrobial activity of their extracts will be assayed against clinically relevant strains of bacteria (Staphylococcus aureus MRSA, Pseudomonas aeruginosa, Escherichia coli) and fungi (Candida albicans, Trichophyton rubrum, Malassezia furfur, Fusarium solani and Aspergillus niger). The methodology includes controlled germination of the species, sampling leaves from seedlings (3-4 months) and adults, preparation of ethanolic extracts, followed by chemical fractionation and analysis by HPLC-HRESI, GC-MS and NMR. Biological tests will be carried out on extracts, fractions and isolated compounds, by means of disk diffusion tests, determination of the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal/Fungal Concentration (MBC/FC), disk diffusion susceptibility test and biofilm inhibition. The results will provide data to test the hypothesis of chemical variability as part of defense strategy of seedlings and to use it as cues to finding novel bioactive compounds from plant species. (AU)