Antimicrobial potential of Jurema preta and umburana, native species of the Caatinga biome, on Staphylococcus isolated from small ruminants with mastitis

Abstract

Mastitis is responsible for both damage to animal health and economic losses to the industry. To identify effective treatments for this disease, products extracted from a variety of plants with antimicrobial potential have gained attention. The present study aimed to assess the in vitro antibacterial potential of the ethanolic extract of two plant species from the Caatinga biome against bacteria isolated from small ruminants with subclinical mastitis. The leaves of Mimosa tenuiflora and Commiphora leptophloeos were dried and processed to obtain crude ethanolic extracts and their phenolic composition was evaluated. In total, 33 Staphylococcus spp. isolates from the bacterial collection of the Laboratory of Food Quality Control of IF SERTÃO-PE were used for evaluation of biofilm production. Furthermore, an antimicrobial susceptibility test was conducted using the minimal bactericidal concentration (MBC) method against the two ethanolic extracts. The toxic potential was measured through a toxicity test with Artemia salina. The quantification of the phenolic compounds revealed that the ethanolic extracts of M. tenuiflora and C. leptophloeos possessed higher amounts of myricetin (43.2 and 294.9 mg in 10 g, respectively) in relation to the other compounds. A 39.4% positivity rate was observed in the nuc gene investigation. The biofilm production analysis revealed that 96.9% of the isolates produced biofilm, evidencing the evolution the microorganisms regarding the development of resistance mechanisms. The MBC results showed an inhibition range between 195.30 and 3125.00 µg mL-1 and between 781.20 and 6250.00 µg mL-1 for the extracts of M. tenuiflora and C. leptophloeos, respectively. The M. tenuiflora extract showed the highest activity, suppressing 100% of the bacterial isolates (n=26), whereas the extract of C. leptophloeos showed an inhibition percentage of 69.23%. The crude ethanolic extract (EEB) of M. tenuiflora was found to be toxic, presenting a DL50 of 118.356 µg mL-1. In contrast, the EEB of C. leptophloeos was found to be non-toxic (DL50 = 1527.430 µg mL-1). In conclusion, both native Caatinga species presented antibacterial activity and myricetin was the major compound. These findings highlight the need for further studies regarding the identification of anti-mastitis products from natural extracts.