Disposition of [14C]povidone after oral administration to the rat

The Effect of PVP Molecular Weight on Dissolution Behavior and Physicochemical Characterization of Glycyrrhetinic Acid Solid Dispersions

The effect of polyvinylpyrrolidone (PVP) as glycyrrhetic acid (GA) solid dispersions carrier at different molecular weights on the dissolution behavior and physicochemical properties was investigated. PVP-GA-SDs prepared with all four molecular weight PVPs displayed good enhancement of dissolution rate and equilibrium solubility compared with pure drug and corresponding physical mixtures. The results showed that the enhancement effect of molecular weight on dissolution rate and equilibrium solubility follows $\text{PVP}\text{K}30>\text{PVP}\text{K}60>\text{PVP}\text{K}17>\text{PVP}\text{K}15$ . In addition, the dissolution rate and solubility of the SDs with a carrier-drug ratio of 8 : 1 were better than the samples of 4 : 1. The DSC and XRD patterns showed that the crystallization of GA in SDs prepared by PVP K30 and PVP K60 was significantly inhibited, and both were transformed to amorphous. Based on FTIR and Raman detection, a hydrogen-bond between PVP and drug molecules is formed. SEM results showed that there were no significant differences in the appearance of SDs prepared with four PVPs, and no crystalline morphology of GA was seen. In conclusion, the findings of this study demonstrated that the dissolution performance of the PVP-GA-SDs prepared by the solvent method is related to the molecular weight of PVP, and the change in the molecular weight of PVP does not cause a monotonic change in dissolution of GA. The samples with PVP K30 as the carrier have the best dissolution performance.

Final Report On the Safety Assessment of Polyvinylpyrrolidone (PVP)

Polyvinylpyrrolidone (PVP) is a linear polymer of 1-vinyl-2-pyrrolidone monomers used as a binder, emulsion stabilizer, film former, hair fixative, and suspending agent-nonsurfactant. The molecular weight of the polymer ranges from 10,000 to 700,000. PVP K-30, with an average molecular weight of 40,000, is typically used in cosmetic formulations. The highest concentration reported to be used is 35%. There was no significant absorption of PVP K-30 given orally to rats, and the acute oral LD50 was >100 g/kg for rats and guinea pigs. Neither toxic effects nor gross lesions were found in rats maintained for two years on a diet containing 10% PVP K-30. Short-term PVP inhalation studies produced mild lymphoid hyperplasia and fibroplasia in rats, but no inflammatory response. In animal studies, no evidence of significant ocular irritation, skin irritation, or skin sensitization was found at PVP-iodine solution concentrations of 10%. While PVP-iodine is not a cosmetic ingredient, these negative findings were considered to support the safety of the PVP component. Undiluted PVP K-30 was not a dermal irritant or sensitizer in clinical tests. No developmental toxicity was seen in vehicle controls where PVP was used as a vehicle for another agent. In certain assay systems, PVP was genotoxic, but was negative in the majority of studies. Orally administered PVP significantly decreased the rate of bladder tumors in mice exposed to bracken fern. Several studies tested the carcinogenicity of subcutaneous implants of particulate PVP in rats, mice, and rabbits. Although the majority of these studies conducted in rats were positive, tumors (sarcomas) were localized to the site of implantation. Based on the available data, it was concluded that PVP is safe as used in cosmetics.

Induction of apoptosis and cell cycle arrest by polyvinylpyrrolidone K-30 and protective effect of alpha-tocopherol

Polyvinylpyrrolidone is a macromolecular polymer with widespread use in industry as well as in medicine for various purposes. Its effect on cells cultured in vitro, however, has not been fully investigated. To elucidate this issue, we studied the influence of PVP K-30 on cultured HeLa cells. PVP K-30 treatment produced a dose- and time-dependent toxicity to HeLa cells. Cells exposed to PVP K-30 exhibited several morphological features of apoptosis. Gel electrophoresis of DNA from PVP K-30-treated cells showed typical apoptotic ladder. And flow cytometric analysis demonstrated that PVP K-30 induced cell cycle arrest at G2/M phase and the subsequent appearance of sub-G1 population. In addition, it was shown that procaspase-3 was activated in response to PVP K-30 treatment. We also found that alpha-tocopherol efficiently protected HeLa cells from PVP K-30 cytotoxicity. This is the first demonstration that PVP K-30 could induce apoptosis in HeLa cells and cell cycle arrest at G2/M phase, and that PVP K-30 toxicity could be attenuated by alpha-tocopherol.

Bread Staling: Molecular Basis and Control

The molecular basis of staling is examined by reviewing what is known about the components of wheat flour, factors that affect staling rate, and the various mechanisms that have been proposed. The conclusion reached is that bread staling is a complex phenomenon in which multiple mechanisms operate. Polymer crystallizations with the formation of supermolecular structures are certainly involved. The most plausible hypothesis is that retrogradation of amylopectin occurs, and because water molecules are incorporated into the crystallites, the distribution of water is shifted from gluten to starch/amylopectin, thereby changing the nature of the gluten network. The role of additives may be to change the nature of starch protein molecules, to function as plasticizers, and/or to retard the redistribution of water between components. Nothing more definite can be concluded at this time.

Arabinose fermentation by Lactobacillus plantarum in sourdough with added pentosans and alphaalpha-L-arabinofuranosidase: a tool to increase the production of acetic acid

Sixty-five strains of obligately and facultatively heterofermentative sourdough lactic acid bacteria were screened for their capacity to grow optimally in the presence of arabinose, ribose and xylose as carbon sources. Lactobacillus alimentarius 15F, Lact. brevis 10A, Lact. fermentum 1F and Lact. plantarum 20B showed higher growth rate, cell yield, acidification rate and production of acetic acid when some pentoses instead of maltose were added to the SDB medium. Lactobacillus plantarum 20B used arabinose also in a synthetic medium where complex growth factors such as yeast extract were omitted. Other Lact. plantarum strains did not show the same property. Pentosan extract was treated with alpha-L-arabinofuranosidase from Aspergillus niger or endo-xylanase from Bacillus subtilis to produce hydrolysates containing mainly arabinose and xylose, respectively. In particular, the hydrolysate containing arabinose substantiated the growth and the production of lactic acid and, especially, of acetic acid by Lact. plantarum 20B. Sourdough fermentation by Lact. plantarum 20B with addition of pentosan extract and alpha-L-arabinofuranosidase increased the acidification rate, titratable acidity and acetic acid content compared with traditional sourdough. A facultatively heterofermentative strain, Lact. plantarum 20B, also produced a sourdough with an optimal fermentation quotient.