Phytochemical determination and antimicrobial activity of plant extracts from Cinnamomum amoenum (Ness) Kosterm. (Lauraceae) against salmonella spp. of poultry importance

Abstract

Salmonellosis is a zoonotic disease that affects commercial birds and causes major economic and productivity losses in the poultry sector. Belonging to the Enterobacteriaceae family, the Gram-negative bacillus of the genus Salmonella has presented itself as a health problem in recent years, as there has been a considerable increase in bacterial resistance, due to the indiscriminate use of antimicrobials as growth promoters. Given this context, bioactives from Brazilian flora, considered one of the most abundant in biodiversity, emerge as an alternative to the use of synthetic products. Thus, this work aimed to determine the chemical compounds of the native species Cinnamomum amoenum (Ness) Kosterm, as well as evaluate the antimicrobial activity of aqueous, ethyl acetate, hexane and ethanolic extracts against different serovars of the genus Salmonella. To obtain the extracts, the plant leaves were dried at 40°C and ground in a knife mill. Subsequently, sterilized by vacuum filtration and roto-evaporated, to completely remove the solvent. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (CBM) were performed using the broth microdilution method, with serial concentrations ranging from 200-0.09 mg/mL of the extract. As a positive control, gentamicin was used at a concentration of 200 mg/mL. Phytochemical tests revealed the presence of flavonoids, steroids and tannins, the latter present only in the aqueous and ethanolic extracts. Regarding antimicrobial activity, the ethanolic, hexane and ethyl acetate extracts showed inhibitory/bactericidal activity for all tested serotypes and the aqueous extract showed no activity on the tested serotypes. The ethanolic extract and ethyl acetate presented MIC ranging between 25 and 50 mg/mL and MBC ranging between 50 and 100 mg/mL. The hexane extract presented MIC ranging between 50 and 100 mg/mL and MBC with 100 mg/mL. The most susceptible serotypes for the ethyl acetate extract were S. Newport, S. Gallinarum, S. Montevideo, while for the ethanolic extract the most susceptible serotypes were S. Typhimurium, S. Mbandaka, S. Infantis, S. Heidelberg and S. Enteritidis. The results suggest that C. amoenum extracts have antimicrobial potential and could be a viable alternative to be used in poultry farms, thus being a more sustainable and less harmful approach to the consumer, who will be free from overdoses of synthetic antimicrobials that are commonly used. Furthermore, it is essential that new studies regarding the biological activities of C. amoenum are carried out, in order to validate its use in the control of poultry Salmonella.