Artigos
URI permanente para esta coleçãohttps://repositorio.fei.edu.br/handle/FEI/800
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- DSC analysis of the influence of time and concentration of Stryphnodendron adstringens extract on corneal cross-linking(2022-11-11) BERSANETTI, P. A.; MARQUINI, A. A.; Andreia de Araújo Morandim Giannetti© 2022, Akadémiai Kiadó, Budapest, Hungary.Keratoconus is an ectasia that leads to reduced stiffness of the cornea, which acquires a conical shape. Many studies are being carried out aiming at new treatments that lead to the recovery of these cross-links. Therefore, the efficiency of the Stryphnodendron adstringens butanolic extract in promoting cross-linking in corneal stroma of porcine eyes was analyzed. The influence of concentration of this plant extract to form cross-links was analyzed, as well as the influence of the contact time. The denaturation temperature results obtained for corneas treated with 1, 2, or 4% of the barbatimão butanolic extract show an increase of 3.84, 11.37, and 33.23%, respectively. These results suggest a rise in the number of cross-links. As for the contact time of the cornea with the 2% solution of the butanolic extract, it appears that the ideal time was 60 min. Enzymatic digestion assays confirm a decrease of 39% and 59% in the relative area and relative mass of corneas in the control group, while for the group treated with the barbatimão extract, these values were close to 0% and 9%, respectively. Therefore, it was possible to verify the efficiency of the barbatimão butanolic extract in modifying the stroma of porcine corneas, which promoted an increase in resistance to thermal and enzymatic degradation.
- DSC characterization of enzymatic digestion of corneas treated with plant extracts rich in polyphenols(2019) Bersanetti P.A.; da Cruz L.G.I.; Carlstron R.; Schor P.; Morandim-Giannetti A.A.© 2019, Akadémiai Kiadó, Budapest, Hungary.Keratoconus is a progressive disease that affects patients’ quality of life by producing corneal irregular astigmatism and low vision as the cornea becomes thinner and presents a conical protrusion. Inducing cross-linking in keratoconic corneal stroma is the current preventive intervention that effectively blocks the progression of this ectasia. As a result of this process, there is an increase in biomechanical strength and resistance of the cornea. In this context, two plant extracts rich in polyphenols (Euterpe oleracea and Stryphnodendron adstringens) have been tested in this study to compact and stiffen the tissue, and its effect was evaluated by enzymatic digestion of porcine corneas. Thermal analysis by DSC was employed to verify the corneal resistance to degradation induced by the plant extracts. The values of temperature and enthalpy of denaturation at the initial time were: 65.6 ± 0.3 °C/3.8 ± 0.3 J g−1; 79.4 ± 0.5 °C/5.5 ± 0.4 J g−1; and 93.1 ± 1.2 °C/8.0 ± 0.6 J g−1, respectively, for the control, E. oleracea, and S. adstringens groups. After 24 h of collagenase digestion, these values were: 60.1 ± 0.8 °C/1.3 ± 0.1 J g−1; 78.1 ± 1.0 °C/5.6 ± 0.6 J g−1; and 93.2 ± 0.6 °C/8.1 ± 0.06 J g−1, respectively. These results show that there was no decrease in temperature and enthalpy of denaturation (p < 0.01) in corneas of the groups treated with the E. oleracea or S. adstringens extracts. However, in the control group, the temperature and the enthalpy decreased by approximately 8% and 65%, respectively. Therefore, this work demonstrated for the first time that plant extracts rich in polyphenols were efficient in decreasing the digestion and increasing the denaturation temperature of corneas.
- DSC characterization of rabbit corneas treated with Stryphnodendron adstringens (Mart.) Coville extracts(2018) da Cruz L.G.I.; Moraes G.A.; Nogueira R.F.; Morandim-Giannetti A.A.; Bersanetti P.A.© 2017, Akadémiai Kiadó, Budapest, Hungary.Keratoconus is an eye ectasia that affects the cornea causing distortion of vision. Corneal crosslinking promoted by riboflavin photo-stimulated at 365 nm is a treatment used successfully to block the keratoconus progression. In this study, we characterize rabbit corneas subjected to enhanced crosslinking using different vegetable extracts prepared from Stryphnodendron adstringens (Mart.) Coville bark by differential scanning calorimetry. The extracts tested in this study were: aqueous, ketonic, ethanolic, ethyl acetate and hydroalcoholic, which revealed high levels of polyphenols, such as proanthocyanidins. The corneas, obtained from the slaughter rabbits, were divided into groups: control (consisting of untreated corneal samples) and S. adstringens, where the samples were subjected to 4% vegetable extracts for 2 h. The DSC profiles of the corneas were obtained in nitrogen atmosphere. The results showed that temperature and enthalpy of denaturation of the corneal samples treated with S. adstringens were higher than the control group. The control group presents temperature and enthalpy values of 59.8 ± 1.1 °C and 24.6 ± 2.7 J g−1, respectively. After crosslinking with ketone extract, the values were 90.1 ± 1.1 °C and 39.9 ± 2.7 J g−1. These results show that S. adstringens is efficient to increment the crosslinking level of the corneas.