Construction, in vitro release and rheological behavior of apigenin-encapsulated hexagonal liquid crystal

Natural Biocidal Compounds of Plant Origin as Biodegradable Materials Modifiers

The article presents a literature review of the plant origin natural compounds with biocidal properties. These compounds could be used as modifiers of biodegradable materials. Modification of polymer material is one of the basic steps in its manufacturing process. Biodegradable materials play a key role in the current development of materials engineering. Natural modifiers are non-toxic, environmentally friendly, and renewable. The substances contained in natural modifiers exhibit biocidal properties against bacteria and/or fungi. The article discusses polyphenols, selected phenols, naphthoquinones, triterpenoids, and phytoncides that are natural antibiotics. Due to the increasing demand for biodegradable materials and the protection of the natural environment against the negative effects of toxic substances, it is crucial to replace synthetic modifiers with plant ones. This work mentions industries where materials containing natural modifying additives could find potential applications. Moreover, the probable examples of the final products are presented. Additionally, the article points out the current world's pandemic state and the use of materials with biocidal properties considering the epidemiological conditions.

A colorimetric method for screening α-glucosidase inhibitors from flavonoids using 3,3',5,5'-tetramethylbenzidine as a chromogenic probe

A facile and novel colorimetric method for screening of α-glucosidase inhibitors (AGIs) from flavonoids using 3,3',5,5'-tetramethylbenzidine (TMB) as a chromogenic probe is proposed. This method is based on the colorimetric detection of ascorbic acid (AA) through the TMB oxidation reaction catalyzed by horseradish peroxidase (HRP) in the presence of hydrogen peroxide (H₂O₂). In the TMB/H₂O₂/HRP system, HRP catalyzes the oxidation of H₂O₂ to ‧OH radical which oxidizes TMB to blue-colored oxidized TMB (oxTMB). In the presence of AA, the production of ‧OH radical is suppressed and causes the decrease of oxTMB, resulting in the fading of the blue color and the decrease of absorbance at 652 nm. Based on this, the existence of AA can be facilely identified. In the 2-O-α-d-glucopyranosyl-l-ascorbic acid (AA-2 G)/α-glucosidase (α-Glu) system, the produced AA inhibits the oxidation of TMB to blue-colored oxTMB. In the presence of AGIs, the production of AA is inhibited, which inhibits the reduction of oxTMB, resulting in a blue color recovery and an increase of the absorbance at 652 nm. Based on this, the colorimetric method is developed for screening of AGIs from 7 flavonoids.

Temperature/pH-Responsive Hexagonal Liquid Crystal for Curcumin Release

The temperature/pH-responsive hexagonal liquid crystal constructed in a polyoxyethylene (20) sorbitan monooleate (Tween 80)/water-soluble chitosan (WCS)/ethyl oleate (EtOL)/H₂O system was used to encapsulate curcumin. We discuss the effect of temperature and pH on the in vitro release of curcumin and the rheological properties of a curcumin-encapsulated liquid crystal. The drug-encapsulated hexagonal phase containing relatively high WCS content (9.9 wt %) exhibited good temperature response, as indicated by three phase transformation temperature obtained by temperature scanning. The viscosity of the drug-encapsulated hexagonal phase decreased as the temperature rose, which exhibited diverse constancy and temperature sensitivity. Also, the in vitro release rate of curcumin increased as the temperature increased. After introducing WCS, the release rate of curcumin decreased obviously the pH dependence, where the release of curcumin was slower as the pH was higher. All of the results indicated that the temperature/pH-responsive hexagonal liquid crystals were proposed to be potential slow release carriers to deliver curcumin.