Yerba Mate Extract in Microfibrillated Cellulose and Corn Starch Films as a Potential Wound Healing Bandage

Abstract

Microfibrillated cellulose films have been gathering considerable attention due to their high mechanical properties and cheap cost. Additionally, it is possible to include compounds within the fibrillated structure in order to confer desirable properties. Ilex paraguariensis A. St.-Hil, yerba mate leaf extract has been reported to possess a high quantity of caffeoylquinic acids that may be beneficial for other applications instead of its conventional use as a hot beverage. Therefore, we investigate the effect of blending yerba mate extract during and after defibrillation of Eucalyptus sp. bleached kraft paper by ultrafine grinding. Blending the extract during defibrillation increased the mechanical and thermal properties, besides being able to use the whole extract. Afterwards, this material was also investigated with high content loadings of starch and glycerine. The results present that yerba mate extract increases film resistance, and the defibrillated cellulose is able to protect the bioactive compounds from the extract. Additionally, the films present antibacterial activity against two known pathogens S. aureus and E. coli, with high antioxidant activity and increased cell proliferation. This was attributed to the bioactive compounds that presented faster in vitro wound healing, suggesting that microfibrillated cellulose (MFC) films containing extract of yerba mate can be a potential alternative as wound healing bandages.

Keywords: Ilex paraguariensis A. St.-Hil; MFC; antibacterial; antioxidant; wound regeneration.

Figure 1

Studied samples for microfibrillated cellulose (MFC) films containing yerba mate extract blended during (D) the defibrillation process and after (A), (a) FTIR spectra, where dashed lines indicate the most important region and the arrow is an increased peak found after the extract is blended. (b) YM extract release and best-fit using Korsmeyer−Peppas, (c) ABTS and DPPH antioxidant scavenging activity and (d) bacteria growth inhibition of 25 mg samples containing yerba mate extract.

Figure 2

(a) Stress−strain curves for tensile tests in DMA, (b) differential scanning calorimetry and (c) thermogravimetric analysis with its (d) first derivative for the MFC films.

Figure 3

(a) Casting films FTIR spectra, assigned numbers signify the formation of new bands by the addition of the specific material. (b) Yerba mate extract release with best-fit using Korsmeyer−Peppas correlation for each curve.

Figure 4

(a) Antibacterial activities of the studied MFC films containing yerba mate extract and (b) antioxidant activities for ABTS and DPPH.

Figure 5

(a) Differential scanning calorimetry and (b) thermogravimetric analysis with its (c) first derivative for the films containing yerba mate extract and (d) stress−strain curves for MFC films performed by DMA.

Figure 6

(a) Cell viability elution assay gray colour assigned to pure element (MFC), green is addition of YM10 and blue for the various samples containing YM20, (b) phosphorylated NF-κB p65 activity and (c) wound healing in vitro scratch assay at 25 mg/mL, (i) control, (ii) MFC, (iii) MFC+YM10, (iv) MFC+YM20, (v) MFC+YM20+STC, (vi) MFC+YM20+GLY, (vii) MFC+YM20+STC+GLY; same letters in each composition do not differ by Tukey’s test (p < 0.01).