Stella Martins Castro¹, Gabrielle Lavor de Queiroz¹, Marilia dos Reis Nery Chen¹, Fernanda Sampaio Cavalcante², Carla Monteiro Leal¹, Ivana Correa Leal ¹

Introduction: The genus Staphylococcus is divided into two groups: coagulase-positive (CoPS) and coagulase-negative (CoNS). The main representative of CoPS is the species S. aureus, while for CoNS, the main ones are S. haemolyticus and S. epidermidis, in which both can indirectly induce sepsis in neonates and have a high capacity for biofilm formation. Moreover, their readiness in acquiring resistance to antimicrobials, contribute to increased morbidity and mortality. Therefore, it’s essential to explore new therapeutic alternatives for the treatment of infections caused by these pathogens. This study aimed to investigate the chemical profile of Inga laurina fractions from the bark, pulp, seeds and leaves, as well as to investigate their antibacterial and antibiofilm potentials against Staphylococcus spp. strains isolated from a Neonatal Intensive Care Unit (ICU). Material and Methods: The leaves, bark, pulp and seeds of Inga laurina were collected at NUPEM-UFRJ/Macaé and conditioned in an oven up to dryness (except pulp). After, the material were macerated with ethanol and obtained the respective crude extracts, that were subjected to liquid-liquid partitioning, yielding n-hexane (Hex), dichloromethane (DCM), ethyl acetate (EtOAc), n-butanol (BuOH), and aqueous residue fractions. These fractions were evaluated for antibacterial activity against 25 strains of S. aureus, S. haemolyticus, and S. epidermidis isolated from neonates in the ICU (CAAE: 25808819.4.0000.5699), using the macrodilution method at concentrations ranging from 128 to 512 μg/mL, in duplicate. Bacterial strains and fractions that demonstrated susceptibility were further evaluated for their ability to prevent biofilm formation at sub-MIC concentrations (<128 μg/mL). The EtOAc, BuOH, and aqueous residue fractions were analyzed by LC-HRMS/MS using an ESI ionization source in the positive mode. The raw data were processed using MZmine 4.2 software and used to construct molecular networks on the GNPS2 platform via the feature-based molecular networking tool. Results and Discussion: Among the fractions evaluated, the ethyl acetate leaf fraction (PAF) stood out, inhibiting approximately 88% of the Staphylococcus sp. strains tested. PAF was able to inhibit two S. aureus strains at 512 μg/mL. Other S. aureus strains (n=5), as well as S. haemolyticus (n=10) and S. epidermidis (n=3), were sensitive at 256 μg/mL. Only one S. epidermidis strain showed inhibition at 128 μg/mL. In the antibiofilm activity evaluation, the EtOAc fraction of the bark (PAC) showed satisfactory results against a S. aureus strain, with 95% inhibition at 128 μg/mL. However, PAF demonstrated greater inhibition against another S. aureus strain, achieving 84% inhibition at 64 μg/mL. LC-HRMS/MS analysis of PAF revealed the presence of the following compounds: Myricetin-3-O-(2″-O-galloyl)-rhamnopyranoside (1), Myricetin-3-O-hexoside (2), Quercetin-3-O-(2″-galloyl)-rhamnoside (3), Myricetin-3-O-rhamnoside (4), Quercetin (5), and Myricetin (6). Conclusion: The I. laurina species showed antibacterial and antibiofilm potential, mainly in the ethyl acetate fraction of the leaves. The analysis of the chemical profile allowed the annotation of flavonoids, which may be associated with this potential.

Agradecimentos: Acknowledgments: Faperj, CNPq and CAPES for financial support. CAPES for scholarship.