Papers by Keyword: Phospholipid

Abstract: Silymarin is a unique flavonoid complex isolated from milk thistle (Silybum marianum). It has been widely used as a hepatoprotective agent. Orally administered silymarin can be absorbed rapidly but only 20-50% of silymarin will be absorbed through gastrointestinal tract, resulting in low bioavailability. Those limitations are due to its low solubility, either in water and oil, and its low intestinal permeability. This study was aimed to develop silymarin-containing phytosome in order to improve the bioavailability of silymarin with sufficient safety and stability. This system consisted of silymarin-phospholipid complex prepared by solvent evaporation method, which was incorporated to form phytosome vesicles using thin layer method with various concentrations and molar ratios of silymarin and phospholipid. The vesicle size of phytosome was reduced with sonication. The results demonstrated that formula with 2% silymarin-phospholipid complex and molar ratio of silymarin to phospholipid of 1:5 showed the best phytosomal characteristics, with mean vesicle diameter of 133.534 ± 8.76 nm, polidispersity index of 0.339 ± 0.078, entrapment efficiency of 97.169 ± 2.412 %, and loading capacity of 12.18 ± 0.30 %. The preparation remained stable after freeze-thaw stability test. Analysis of Infrared spectroscopy and Differential Scanning Calorimetry confirmed the presence of physical and chemical interactions between silymarin and phospholipid within complex formation. Well formed and discrete vesicles were revealed by Transmission Electron Microscopy analysis, drug content measurement, and freeze-thaw stability test.

Abstract: Hevea brasiliensis natural rubber (NR) latex is a very important commercial source of elastomers. It is not only a source for dry NR rubber but also the feedstock for the latex glove dipping industry. The particles of freshly tapped latex are known to be stabilized by proteins and lipids that come with the latex from the tree. These non-rubbers [, especially proteins and lipids, confer to the rubber and latex excellent properties unsurpassed by any synthetic latex [. Recent structural studies of NR revealed that the NR molecules comprise of 2 trans-isoprene units connected to a long-chain cis-isoprene units. Two terminal groups, referred to as ω and α, have been postulated to link with mono-and di-phosphate groups associated with phospholipids by H-bonding at the α-terminal, whereas the ω-terminal is a dimethylallyl group links to protein by H-bonding [. Although numerous studies have been published on the surface structure of the natural rubber particle [4-, none of these offered a direct in situ visualization of the intact particle surface. This is because of any attempt to remove this surface layer of proteins and lipids results in an immediate destabilization of the latex. The second part focused on the using of Atomic Force Microscopy (AFM) and Confocal Fluorescence microscopy to visualize and delineate the structure of the proteins and lipids layer on the latex particle surface in situ.

Abstract: The impact of physicochemical character of the W/O microemulsion droplet on the reactivity of phospholipase A₂ (PLA₂) was investigated for optimal design of the micro-reactor. Hydrophobicity of micro water pool and fluidity of micro-scaled interface of W/O microemulsion droplet were dominant factors to determine the appearance of maximum reactivity. Phosphatidylcholine (PC) in this system performed not only as a substrate for PLA₂ but also as an amphiphilic molecule to form W/O microemulsion droplet. The organic phase was composed by isooctane (C₈*) as a main solvent and 1-butanol (C₄) as a co-solvent. The molar ratio was fixed as isooctane:1-butanol =11:1. The water content in the W/O microemulsion was indicated by the molar ratio of H₂O moles to PC moles presented by Wsoln [-](≡[mol-H₂Osoln]/[mol-PC]). By the increasing of the water content from 1 to 5, the reactivity of PLA₂ was remarkably increased from 0.01 to 0.03 [mM･s^-1･mg-PLA₂^-1]. Over 5 of Wsoln range, the reactivity was decreased. The optimal water content was indicated as Wsoln=5 [-]. The hydrophilicity of micro water pool and the interfacial fluidity of the water pool were detected by the signal of the fluorescence probes, Coumarin 343 and TMA-DPH, respectively. The hydrophobicity was decayed with the increasing of the water content. More than 10 of Wsoln, the hydrophobicity was fully decayed and achieved to bulk aqueous one. The interfacial fluidity was decreased with the increasing of the water content. In more than Wsoln of 5, the reactivity was decreased by the decline of the collision frequency between PLA₂ and PC molecule due to lower fluidity of micro-scaled interface.

Abstract: The calf serum solution was defined as the international standard lubricant for wear characterization of artificial hip joints. It is, however, known that its composition varies according to age, manufacturing processes or production areas of bovine cattle, and that the difference in composition has large effect on the wear characterization. It was difficult to compare the results obtained by different laboratories. Therefore, it is desirable to develop an artificial lubricant whose composition can be always set to a specified value as an alternative to bovine serum. In the present study, the effect of each major constituent in bovine serum on wear property was studied by hip simulator. As a result, transparent and stable lubricant solutions were prepared. It showed quite similar wear property to bovine serum by controlling the composition. These results serve as a guide to propose the new lubricant suitable for the wear characterization of hip joint.