Bacterial nanocellulose loaded with bromelain and nisin as a promising bioactive material for wound debridement.

The bacterial nanocellulose (BnC) membranes were produced extracellularly by a novel aerobic acetic acid bacterium Komagataeibacter melomenusus. The BnC was modified in situ by adding carboxymethyl cellulose (CMC) into the culture media, obtaining a BnC-CMC product with denser fibril arrangement, improved rehydration ratio and elasticity in comparison to BnC. The proteolytic enzyme bromelain (Br) and antimicrobial peptide nisin (N) were immobilized to BnC matrix by ex situ covalent binding and/or adsorption. The optimal Br immobilization conditions towards the maximized specific proteolytic activity were investigated by response surface methodology as factor variables. At optimal conditions, i.e., 8.8 mg/mL CMC and 10 mg/mL Br, hyperactivation of the enzyme was achieved, leading to the specific proteolytic activity of 2.3 U/mg and immobilization efficiency of 39.1 %. The antimicrobial activity was observed against Gram-positive bacteria (S. epidermidis, S. aureus and E. faecalis) for membranes with immobilized N and was superior when in situ modified BnC membranes were used. N immobilized on the BnC or BnC-CMC membranes was cytocompatible and did not cause changes in normal human dermal fibroblast cell morphology. BnC membranes perform as an efficient carrier for Br or N immobilization, holding promise in wound debridement and providing antimicrobial action against Gram-positive bacteria, respectively.

Antihyperglycemic effect of Vernonia amygdalina and in vitro evaluation of its antiproliferative activity on human osteosarcoma MG-63.

Introduction: the leaves of Vernonia amygdalina (V. amygdalina) are consumed as food in sub-Saharan Africa (SSA). In traditional medicine, this plant is widely used in the treatment of cancer and diabetes mellitus. In the present study, we evaluated the antihyperglycemic and the antiproliferative activities of the hydroalcoholic extract of V. amygdalina leaves (HAEVa). Methods: we conducted an experimental descriptive and analytical study with a prospective data collection from May 2019 to July 2020. For the in vivo study, the experiments were carried out on albino male rats of Wistar strain (Rattus norvegicus). Antihyperglycemic activity was performed in vivo in dexamethasone-induced insulin-resistant rats using the oral glucose tolerance test (OGTT). The biocompatibility and the antiproliferative activity of extract were performed in vitro respectively on rabbit primary dermal fibroblasts (RPDF) and human osteosarcoma MG-63 cells using the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The data were analyzed with the GraphPad Prism software version 5.0.3. The statistical analyses were obtained by the analysis of variance (ANOVA), followed by Bonferroni´s post-test. P<0.05 was considered as the minimal level of statistical significance. Results: regarding to the antiproliferative investigation, extract at 125, 250 µg/mL exhibited a significant cytotoxic effect on human osteosarcoma MG-63 compared to the vehicle (p<0.001) in a dose-response manner after 24h, 48h of exposure to HAEVa. Interestingly, HAEVa in concentrations of 125 and 250µg/ml showed no cytotoxicity (p>0.05) on RPDF after the different times of exposure. However, HAEVa in a high concentration of 500 µg/mL wasn´t biocompatible with RPDF. HAEVa also prevented postprandial blood glucose level in dexamethasone-induced insulin-resistant rats at both doses tested (p>0.05 and p<0.01 at doses of 50 and 100 mg/kg respectively). Conclusion: the results of this study suggest that HAEVa has antiproliferative properties on MG-63 osteosarcoma in vitro and also inhibits in vivo the postprandial blood glucose level in dexamethasone-induced insulin-resistant rats.