In Vitro and Sensory Evaluation of Capsaicin-Loaded Nanoformulations

Capsaicin has known health beneficial and therapeutic properties. It is also able to enhance the permeability of drugs across epithelial tissues. Unfortunately, due to its pungency the oral administration of capsaicin is limited. To this end, we assessed the effect of nanoencapsulation of capsaicin, under the hypothesis that this would reduce its pungency. Core-shell nanocapsules with an oily core and stabilized with phospholipids were used. This system was used with or without chitosan coating. In this work, we investigated the in vitro release behavior of capsaicin-loaded formulations in different physiological media (including simulated saliva fluid). We also evaluated the influence of encapsulation of capsaicin on the cell viability of buccal cells (TR146). To study the changes in pungency after encapsulation we carried out a sensory analysis with a trained panel of 24 students. The in vitro release study showed that the systems discharged capsaicin slowly in a monotonic manner and that the chitosan coating had an effect on the release profile. The cytotoxic response of TR146 cells to capsaicin at a concentration of 500 μM, which was evident for the free compound, was reduced following its encapsulation. The sensory study revealed that a chitosan coating results in a lower threshold of perception of the formulation. The nanoencapsulation of capsaicin resulted in attenuation of the sensation of pungency significantly. However, the presence of a chitosan shell around the nanoformulations did not mask the pungency, when compared with uncoated systems.     

Dual action of hydroxylated diphenylethylene estrogens on protein kinase C1

Protein kinase C (PKC) I (gamma), II (beta) and III (alpha) subspecies are all activated by 1,1-di-(p-hydroxyphenyl)ethylene derivatives (DPE) at micromolar concentrations. This PKC activation depends on the presence of both Ca2+ and phosphatidylserine (PS) but does not require diacylglycerol (DG). DPEs enhance PKC activity at low PS concentrations, but not at saturating PS concentrations. Like DG, DPEs increase the apparent affinity of PKC for PS as well as for Ca2+, but lead to a decrease in the catalytic activity (Vmax). In the presence of saturating DG concentrations, DPEs exhibit an inhibitory action. The derivatives also inhibit the activity of the proteolytic fragment of PKC, protein kinase M. It is concluded that DPEs are mixed-type inhibitors, probably interacting with the catalytic domain of the enzyme.     

FETAL DEVELOPMENT: THE EFFECTS OF MATURATION ON IN VITRO PROTEIN SYNTHESIS BY MOUSE BRAIN TISSUE

—The elucidation of the translational regulatory events which function during the critical fetal and neonatal period is an important prerequisite to our understanding of normal, as well as abnormal, brain growth and differentiation. Brain cell suspensions and cell-free homogenates were employed to study the protein synthetic activity during the maturation of fetal- neural tissue. The results clearly demonstrated that while neural tissue from 1-day postnatal mice was 10 times more active in protein synthesis than brain tissue from adult mice, the former was many fold less active in translational events than fetal neural tissue from 13-day post-zygotic mice. Fetal polypeptide synthetic activity was found to decrease from the 13th day to the 19th day post-zygotic. This decrement in the translational activity was not due to amino acid availability or pools, or to differences, quantitatively or qualitatively, in polysome concentrations. The enhanced rate of protein synthetic activity measured with neural tissue from 13-day post-zygotic mice was shown to be due to an increase in rate of protein synthesis and not to an enhanced rate of protein degradation.     

Un Précurseur de PasteurJ. B. F. Bulliard 1752–1793

Sans résumé     

Bovine papilloma virus plasmids replicate randomly in mouse fibroblasts throughout S phase of the cell cycle

Bovine papilloma virus (BPV) replicates as a multicopy nuclear plasmid in mouse fibroblasts. Using fluorescence activated cell sorting and mitotic selection procedures, we show that the replication of BPV occurs throughout S phase of the cell cycle and that replication is confined to S phase. After one round of chromosomal DNA replication, almost one quarter of BPV plasmids have replicated more than once, while a similar number of plasmids have not replicated at all. While multiple forms of BPV exist in the cell, all forms show the same pattern of replication. These results are consistent with a model in which BPV plasmids are chosen at random for replication throughout, and only during, S phase and support the view that the completion of S phase is a specifically activated event in the cell cycle rather than simply the end of one round of chromosomal DNA replication.