Octenyl succinate starch films with nut by-products extracts: antimicrobial properties for medical applications

Abstract

The use of starch-based films with rich phenolics extracts for medical purposes has been increasing due to the biocompatible characteristics of starch and the antimicrobial properties of phenolic extracts. Therefore, the aim of this work was to evaluate the antibacterial properties of octenyl succinated starch (OSS) based films with nut by-product extracts: pecan nutshell extract (PSE) and hazelnut skin extract (HSE). The OSS (0.013 degree of substitution) showed a greater swelling, pasting and gelatinization properties than native starch (NS), indicating that the film forming property was improved after the modification. Pecan nutshell and hazelnut skin were a great source of phenolic compounds (PC) (656.46±4.91 and 693.00 ± 5.65 mgEAG per-g of extract, respectively). Protocatehuic acid, epicatechin gallate, gallic acid and rutin were majority identified compounds. The PSE and HSE showed minimum inhbitory concentrations (MIC) against Staphylococcus aureus ATCC 6538P, Staphylococcus epidermidis ATCC 12228 (MIC= 250 μg/mL) and Klebsiella pneumoniae ATCC 13883 (MIC= 450 and 650 μg/mL, PSE and HSE, respectively). Besides, biofilm formation for all bacteria was reduced at MIC of both extracts. The PC of the extracts were dispersed trough the polymeric matrix of the OSS films. Resulting in homogeneous films, confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Additionally, both extracts improved the water resistance, UV-Light barrier and mechanical properties (rigidity decrease). Films with 2500 and 5000 μg per-mL of extracts, did not show inhibition zone, however, there was not visual growth of Staphylococcus spp. below the films. In liquid medium, films with 5000 μg per-mL of extracts decrease the growth of Staphylococcus spp., Pseudomonas aeruginosa ATCC and K. pneumonia ATCC 13883. The OSS films with PSE or HSE presented suitable characteristics and properties that demonstrate its potential as a medical material, for the prevention of bacterial infections.