Toward a greener multifunctional pharmaceutical excipient: in vivo safety evaluation of nanofibrillated cellulose from tobacco stalk

Tobacco stalk is a cellulose-rich material and a sustainable alternative to be applied as a plant-based nanofibrillated cellulose (NFC) source. NFC use has garnered attention in the development of oral pharmaceutical forms, despite concerns about its safety due to the adverse effects of nicotine on health. Therefore, we aimed at establishing the safety of NFC derived from tobacco stalk for its potential use as a novel pharmaceutical excipient, exploring its potential functions for tablet production. We conducted acute and subchronic oral toxicity tests in adult female Wistar rats. Initially, individual animals received sequential doses (175-5,000 mg·kg-1) for 24 hours followed by a careful observation of any toxic effects. Subsequently, 20 rats were divided into four groups for a subchronic assay, evaluating toxicity signs, body weight changes, hematological, biochemical, and histopathological parameters. No deaths or other clinical toxicity signs were observed in either the acute or the subchronic assays. We noticed a significant reduction in body weight gain (p < 0.05) after 14 days. We found statistical differences for hematological and biochemical parameters, unrelated to dosage. There were no observed toxic effects, and tobacco stalk ingestion did not adversely affect organ morphology in the histopathological evaluation. The oral administration of NFC at 5,000 mg·kg-1 per day for 28 days was well-tolerated by treated rats, with no reported deaths. In conclusion, NFC derived from tobacco stalk has shown to be a sustainable and safe alternative for use as an excipient at experimental doses, demonstrating compatibility with its proposed applications.

PHMB-loaded PDMS and its antimicrobial properties for biomedical applications

Given the global panorama of demands in the health area, the development of biomaterials becomes irreducible for the maintenance and/or improvement in the quality of life of the human being. Aiming to reduce the impacts related to infections in the healing processes of the dermal structure, the present work proposes the development of polydimethylsiloxane (PDMS) based membranes with the incorporated polyhexamethylenebiguanide (PHMB) antimicrobial agent. In the present study, the antimicrobial and antibiofilm properties of polydimethylsiloxane (PDMS) films incorporated with 0.1, 0.3, and 0.5% (w/w) of polyhexamethylene biguanide (PHMB) were evaluated, aiming the development of a protective biomaterial that avoids cutaneous infections from the autochthonous and allochthonous microbiota. The disk diffusion of PHMB-loaded PDMS has shown the growth inhibition of Escherichia coli (ATCC 9637), Pseudomonas aeruginosa (ATCC 27953), Acinetobacter baumannii (ATCC 19606), Staphylococcus aureus (ATCC 6538), Staphylococcus epidermidis (ATCC 12228), Streptococcus pyogenes (ATCC 19615), Bacillus subtilis (ATCC 6633) and also yeast-like fungi Candida albicans, all microorganisms found on the epidermal surface. Likewise, the present study demonstrated low cytotoxicity of the PHMB-loaded PDMS on HaCaT and L929 cells at lower concentrations (0.1% w/w), indicating the possibility of using the developed material as a dressing for wounds, burns, and post-surgical procedures.

Compatibility study of rosmarinic acid with excipients used in pharmaceutical solid dosage forms using thermal and non-thermal techniques

Rosmarinic acid (RA) is a phenolic compound that presents well-documented anti-inflammatory, antioxidant and antitumor activities, and based on its pharmacological potential and poor bioavailability, several solid dosage forms have been developed to RA delivery. Therefore, in literature, there are no reports about RA compatibility with excipients. In this regard, the aim of the present study was to evaluate, for the first time, the compatibility of RA with excipients commonly used in solid dosage forms at a 1:1 (RA:excipient) ratio using differential scanning calorimetry (DSC), thermogravimetry (TG), Fourier-transform infrared (FTIR), solid-state nuclear magnetic resonance (ssNMR), and isothermal stress testing (IST) coupled with liquid chromatography (LC). The excipients selected were hydroxypropyl methylcellulose (HPMC), microcrystalline cellulose (MCC), lactose monohydrate (LAC), polyvinylpyrrolidone (PVP), talc (TALC), croscarmellose sodium (CCS), and magnesium stearate (MgSTE). According to DSC results, physical interactions were found between RA and HPMC, LAC, CCS, and MgSTE. The TG analyses confirmed the physical interactions and suggested chemical incompatibility. FTIR revealed physical interaction of RA with TALC and MgSTE and the ssNMR confirmed the physical interaction showed by FTIR and excluded the presence of chemical incompatibility. By IST, the greatest loss of RA content was found to CCS and MgSTE (>15%), demonstrating chemical incompatibilities with RA. High temperatures used in DSC and TG analyses could be responsible for incompatibilities in binary mixtures (BMs) with HPMC and LAC, while temperature above 25 °C and presence of water were factors that promote incompatibilities in BMs with CCS and MgSTE. Overall results demonstrate that RA was compatible with MCC and PVP.

Polyurethane/poly(d,l-lactic acid) scaffolds based on supercritical fluid technology for biomedical applications: Studies with L929 cells

Biomaterials can be applied in tissue engineering as scaffolds that resemble the extracellular matrix functioning as a temporary structure for cell proliferation and reconstruction of new organs and tissues. To evaluate the potential use of scaffolds as a biomaterial, this work proposes the development and characterization of polyurethane (PU), poly(D,L-lactic acid) (PDLLA) and polyurethane/poly(d,l-lactic acid) (PU/PDLLA) scaffolds produced by gas foaming technique. The neat polymers and the blends were characterized, in film form, by gel permeation chromatography (GPC), thermogravimetry (TG), differential scanning calorimetry (DSC) and field emission gun scanning electron microscopy (FEG-SEM). After supercritical fluid technology, in scaffolds form, the samples were characterized by FEG-SEM, pore size, density, cytotoxicity and cell adhesion. For film characterization the PU/PDLLA sample presented intermediate characteristics compared to the neat polymers, exhibiting the behavior of both polymers in the sample without phase separation in the FEG-SEM micrograph and bimodal molar weight distribution by GPC. The scaffolds showed interconnectivity and pore size of 141 μm ± 108 μm for PUsc and 52 μm ± 32 μm for PDLLAsc. The PU/PDLLAsc exhibited a bimodal structure in which the PU in the mixture revealed pores of 75 μm ± 57 μm, while for PDLLA, the pore size was 19 μm ± 12 μm. In vitro tests confirmed the adhesion of L929 cells to PUsc, PDLLAsc and PU/PDLLAsc, showing no cytotoxic effect. Finally, it can be concluded that it is possible to produce PU, PDLLA and PU/PDLLA scaffolds by supercritical fluid, which may be applied as biomaterials.

Comparison of black fly species (Diptera: Simuliidae) on an Amerindian reservation with a high prevalence of fogo selvagem to neighboring disease-free sites in the State of Mato Grosso do Sul, Brazil. The Cooperative Group on Fogo Selvagem Research

Fogo selvagem is an autoimmune blistering skin disease that principally occurs among rural Brazilians living in geographically clumped disease foci. Exposure to hematophagous black flies possibly is related to the cause of the disease. We compared the occurrence, proportions, and richness of simuliid species immatures and the biting activity of adult females within a recently discovered, high prevalence focus of fogo selvagem, the Limão Verde Terena Reservation, to that of neighboring regions with no reported cases of fogo selvagem. Nine black fly species were collected from 12 stream sites during 5 trips to the fogo selvagem focus. The species showed longitudinal (upstream-downstream) trends in occurrence, proportions, and richness, and the abundance of simuliid immatures was greater at downstream sites. The most prevalent species at the focus, Simulium nigrimanum (Macquart), dominated the stream sites with highly abundant simuliid assemblages, and was the most common black fly in human bait collections. This species was absent or in very low numbers in neighboring valleys and villages that did not have cases of fogo selvagem.