Chitosan, an all natural polysaccharide, has been previously proposed while an elicitor in vegetation to prevent pathogen infections. in food and pharmaceutical industries as natural food preservers and antibiotic adjuvants. vanB2-C3735 , vanA-C2302 , C5932 (MRSA CC398) , C3658 (linezo-R) , and 4 multiresisatnt Gram-negative bacteria: C4220, C999 (CTX-M-15)  C1370 (CTX-M-15) , C4660 (VIM-2) ; and two Gram-positive foodborne strains ATCC700302 and ATCC1306. The strains are part of the University or college of Trs-os-Montes and Alto Douro and University or college of La Rioja selections. All the bacterial strains were subcultured from the original culture in Mind Heart Infusion (BHI) agar (Oxoid, UK) for 24 h at 37 C. Mller-Hinton (MH) agar (Oxoid, UK) was utilized for the antimicrobial susceptibility assay. All the bacterial strains were subculture from the original culture in Mind Heart Infusion (BHI) agar (Oxoid, UK) for 24 h at 37 C. Mller-Hinton (MH) agar (Oxoid, UK) was utilized for the antimicrobial susceptibility assay. 2.8. Antimicrobial Susceptibility Test The antimicrobial susceptibility assay was performed using Kirby-Bauer disc diffusion method. The measurement of bacterial growth inhibition was carried out as previously explained . Each bacterial strain was seeded in BHI agar plates and incubated over night at 37 C. A few colonies were suspended in physiological means to fix a turbidity equivalent to 0.5 McFarland standard and 100 L was plated onto MH plates. The initial extract remedy of 100 g/mL was diluted with DMSO to 75, 50, 25 and 10 g/mL. Twenty microliters of each extract concentration were loaded on sterile blank discs (6 mm diameter) and the discs were placed onto inoculated MH plates. The plates were incubated for 24 h at 37 C. The inhibition zones were measured with a ruler, recorded and considered as indication for antibacterial activity. Discs loaded with DMSO were used Silmitasertib pontent inhibitor as negative control and antibiotic discs were used as positive control. The test was Silmitasertib pontent inhibitor Silmitasertib pontent inhibitor performed in duplicate. 2.9. Statistical Analysis The results were expressed as mean values and standard deviation (SD). All results were analyzed using IBM SPSS Statistics for Mac, Version 26.0. (IBM Corp., Armonk, New York, NY, USA). One-way analysis of variance (ANOVA) followed by Tukeys HSD Test with = 0.05 was performed. To verify the homogeneity of variances, Silmitasertib pontent inhibitor Levenes was implemented to verify the homogeneity of variances. For the individual phenolic compounds quantification, a Students t-test was used to determine the significant difference, with = 0.05. 3. Results and Discussion 3.1. Phenolic Profile Analysis In this study, Sous?o vines were treated with a chitosan solution and chitosan nanoparticles in order to investigate the effect of these treatments in phenolic compounds, and their consequent influence in the antioxidant and antibacterial activities. Previous studies have investigated the effect of chitosan on the phenolics of grape pomace and wine; however, as far as we know, this is the first report on the chitosan treatment effect on the individual components of grapes: Skins, seeds and stems. Table 1 shows the total phenolic content (TPC), total anthocyanin content (TAC) and total tannin content (TTC) of CTSD the Silmitasertib pontent inhibitor skins, seeds and stems of Sous?o variety grapes with no treatment (control), treated with a chitosan solution and treated with chitosan nanoparticles. Regarding the control group, skins showed a higher TPC, followed by seeds and stems extracts. In contrast, seeds showed a much higher tannin content than the skins or stems extracts. Similar results were obtained in previous studies carried out on other different grape varieties, namely Merlot, Touriga Nacional and Preto Martinho, where the TTC was also highest in the seeds, whereas the stems presented the lowest tannin content [6,34]. Nevertheless, due to the small proportion of this component in the cluster, stem tannins have less importance . The treatment with chitosan seems to have influenced the phenolic content of grape components. There is an increase.