An intraocular dye solution based on lutein and zeaxanthin in a surrogate internal limiting membrane model: a Langmuir monolayer study.

Investigating the role of biomolecules and bioactive molecules associated with membranes is fundamental to comprehend at the molecular point-of-view biochemical and clinical processes that occur at biointerfaces. In this paper we exploit the interaction of an intraocular dye solution based on lutein and zeaxanthin in surrogate internal limiting membrane (ILM) models, consisting of dipalmitoyphosphatidylcholine (DPPC) Langmuir monolayers, pure or mixed with collagen, proteoglycan and laminin. The interactions between the film components occurring at the air-water interface were investigated with surface pressure-area isotherms and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). A natural dye solution based on lutein and zeaxanthin, employed to label ILM in ophthalmic surgery, was incorporated in the ILM model, and the data suggested non-rupture of the structure of the membrane, with predominance of interactions based on intermolecular forces.

Evaluation of piper cubeba extract, (-)-cubebin and its semi-synthetic derivatives against oral pathogens.

The activities of the crude ethanol extract from Piper cubeba seeds, (-)-cubebin and its semi-synthetic derivatives were evaluated against oral pathogens. The crude ethanol extract was more active against Streptococcus salivarius (MIC value of 80 microg/mL). (-)-Cubebin displayed MIC values ranging from 0.20 mm for Streptococcus mitis to 0.35 mm for Enterococcus faecalis. The natural product (-)-cubebin and its semi-synthetic derivative (-)-hinokinin displayed bacteriostatic activity at all evaluated concentrations, as well as fungicidal activity against Candida albicans at 0.28 mm. The O-benzyl cubebin derivative showed fungistatic and fungicidal effects against C. albicans at 0.28 mm and 0.35 mm, respectively. Also, the other dibenzylbutyrolactone derivatives [(-)-6,6'-dinitrohinokinin and (-)-O-(N,N-dimethylaminoethyl)-cubebin] displayed bacteriostatic and fungistatic effects at the evaluated concentrations. Moreover, the semi-synthetic derivative (-)-6,6'-dinitrohinokinin was the most active compound against all the evaluated microorganisms. Therefore, it may be suggested that the presence of the carbonyl group at C-9 plus the introduction of polar groups in the aromatic rings improve the antimicrobial activity of dibenzylbutyrolactone compounds.