Synergism Between Oxytetracycline and Mango Peel Extracts in Antimicrobial Therapy for Aquaculture

• Grant number: 25/22339-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2025
• End date: October 31, 2026
• Field of knowledge: Engineering - Chemical Engineering - Industrial Operations and Equipment for Chemical Engineering
• Principal Investigator: Wanderley Pereira Oliveira
• Grantee: Laura de Sousa da Silva
• Host Institution: Faculdade de Ciências Farmacêuticas de Ribeirão Preto (FCFRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated research grant: 25/13953-3 - Nanotechnological Strategies for Sustainable Antimicrobial Control in Fish Farming, AP.R

Abstract

The indiscriminate use of pharmaceuticals in aquaculture represents a major socio-environmental problem due to water contamination and the selection of resistant bacteria and genes. Therefore, the search for natural alternatives that promote fish health and reduce antibiotic use is essential. Mango peel is an abundant agro-industrial by-product rich in polyphenols-compounds known for their immunomodulatory and antibacterial properties. It may also enhance the efficacy of conventional antimicrobial drugs through synergistic effects, contributing to the reduction of microbial resistance. Based on this context, the present study aims to investigate the synergism between oxytetracycline (one of the two drugs approved for use in aquaculture) and mango peel extracts against pathogens of relevance to fish farming. Extracts obtained through hydroalcoholic extraction of mango peel will be characterized for total polyphenol content, antioxidant potential, and chemical composition by high-performance liquid chromatography (HPLC). Mango peel will be explored as the main component of the system, combined with different concentrations of oxytetracycline. The mixtures will be individually encapsulated to preserve and ensure the sustained release of the compounds in the fish intestine. The encapsulation efficiency of both polyphenols and oxytetracycline, as well as the physicochemical properties of the systems, will be evaluated. Finally, the antibacterial potential of pure oxytetracycline, isolated extracts, and encapsulated mixtures at different ratios will be tested against bacteria isolated from fish using the broth microdilution method. It is expected that the results will contribute to the development of nanotechnological controlled-release systems with lower environmental impact, strengthening practices aligned with the One Health concept and the United Nations Sustainable Development Goals (SDGs).