ABSTRACT
Postbiotic is the term used to define the soluble factors, metabolic products, or byproducts released by live probiotic bacteria or after its lysis. The objective of this study was to carry out the chemical characterization of the postbiotic of Lacticaseibacillus rhamnosus LR-32 and to evaluate its in vitro effect on the development of the Streptococcus mutans biofilm. After the cultivation of the probiotic strain, the postbiotic was extracted by centrifuging the culture and filtering the supernatant. This postbiotic was characterized by using gas chromatography coupled with mass spectrometry (GC-MS), and then it was used to determine the growth inhibition of S. mutans in its planktonic form; additionally, its effects on the following parameters in 48 h biofilm were evaluated: viable bacteria, dry weight, and gene expression of glucosyltransferases and VicR gene. The control group consisted of the biofilm without any treatment. A paired t-test was performed for statistical analysis, with the p-value set at 5%. Seventeen compounds of various chemical classes were identified in the postbiotic, including sugars, amino acids, vitamins, and acids. The treatment with the postbiotic led to an inhibition of the growth of S. mutans in its planktonic form, as well as a decrease in the number of viable bacteria, reduction in dry weight, and a negative regulation of the gene expression of gtfB, gtfC, gtfD, and vicR in its biofilm state, compared with the nontreated group (p < 0.05). The postbiotic of L. rhamnosus impaired the development of S. mutans biofilm.
ABSTRACT
Croton heliotropiifolius Kunth, popularly known as "quince" and "velame," contains a high concentration of volatile oils in the leaves, and widely used in folk medicine as an antiseptic, analgesic, sedative, anti-inflammatory, spasmolytic and local anesthetic. The objectives of this investigation were to (1) identify the phytochemical compounds and (2) assess the cytogenotoxicity of the essential oil extracted from the leaves of C. heliotropiifolius Kunth. The oil was extracted utilizing hydrodistillation and phytochemical profile determined using gas chromatography and mass spectrometry (GCMS). In the toxicogenetics analysis, Allium cepa roots were exposed to 1% dimethylsulfoxide or methylmethanesulfonate (MMS, 10 µg/ml) negative and positive controls, respectively, and to C. heliotropiifolius oil at 6 concentrations (0.32; 1.6; 8; 40; 200 or 1000 µg/ml). The phytochemical profile exhibited 40 chromatographic bands, and 33 compounds identified. α-pinene (16.7%) and 1,8-cineole (13.81%) were identified as the major compounds. Some of these identified secondary metabolites displayed biological and pharmacological activities previously reported including antiseptic, analgesic, sedative, anti-inflammatory as well insecticidal, antiviral, anti-fungal actions. In the A. cepa test, C. heliotropiifolius leaves oil induced cytotoxicity at concentrations of 0.32, 1.6 or 200 µg/ml and genotoxicity at 200 or 1000 µg/ml as evidenced by increased presence of micronuclei and significant chromosomal losses. Based upon our observations data demonstrated that the essential oil of C. heliotropiifolius leaves contain monoterpene hydrocarbons, and oxygenated monoterpenes, sesquiterpenes, and oxygenated sesquiterpenes which are associated with cytotoxic and genotoxic responses noted in on A. cepa cells.
