Lysolecithin

Safety Assessment of Lecithin and Other Phosphoglycerides as Used in Cosmetics

The phosphoglycerides considered in this safety assessment are reported to function primarily as skin and hair conditioning agents, emulsifying agents, and surfactants in cosmetic products and are used up to a maximum reported concentration of 50%. Although phospholipids exert physiologic effects, these are not reproduced by application of phospholipid ingredients to the skin. Given the possibility that Lecithin may be derived from animal sources, it should be noted that the Food and Drug Administration does not permit the use of ingredients made from bovine specified risk materials in cosmetic products. The Expert Panel for Cosmetic Ingredient Safety concluded that the 17 phosphoglycerides are safe in the present practices of use and concentration in cosmetics, as described in this safety assessment.

Composition and physicochemical properties of fasted-state human duodenal and jejunal fluid: a critical evaluation of the available data

Various methods of sampling and analyzing intestinal fluids have been applied over the years. In this report, data that have been published to date about the composition of fasted-state human intestinal fluid (HIF) and its physicochemical properties are summarized and the influence of the methods used to generate the data is discussed. Key physiological parameters summarized include pH, buffer capacity, osmolarity, and ionic strength in both the fasted duodenum and jejunum. Furthermore, the bile salts and phospholipids in the fasted small intestine are addressed in terms of both qualitative and quantitative composition with respect to the different types and degrees of hydroxylation of bile salts. Taurocholate, glycocholate, and glycochenodeoxycholate were identified as the main bile salts. Lysolecithin was identified as the predominant phospholipid species in fasted HIF because of the enzymatic degradation of lecithin. Together with other intestinal surfactants, such as cholesterol and free fatty acids, the influence of bile acids and phospholipids on the surface tension of fasted HIF was evaluated. A good working knowledge of all the above-mentioned parameters is important to optimize the composition of biorelevant media, with a view to improving the prediction of in vivo dissolution and release performance of drugs and dosage forms.

The interaction of penicillins with phospholipids

The interaction of the antibiotics, penicillin G and ampicillin, with sonicated sols of phosphatidylcholine, lysophosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylserine has been examined by Sephadex gel nitration and dynamic dialysis. Nuclear magnetic resonance spectroscopy provided evidence of a predominantly hydrophobic interaction between the antibiotics and the phospholipids, phosphatidylserine and phosphatidylcholine. Confirmation of hydrophobic interaction was provided by a rheological investigation of the effects of urea and guanidine hydrochloride on the antibiotic-phospholipid complex. Penicillin G was found to interact to a greater degree than ampicillin, a result which is of interest in the light of present knowledge of in vivo activity of these antibiotics.

Hydrophilic carotenoids: surface properties and aggregation behavior of a highly unsaturated carotenoid lysophospholipid

The water dispersibility of a hydrophobic carotenoid has been greatly enhanced by using it as the acyl part in the synthesis of a highly unsaturated lysophospholipid. Dynamic light scattering has revealed the formation of stable aggregates with an average hydrodynamic radius of a few nanometers, and absorption spectra show that the aggregates can withstand the addition of ethanol or acetonitrile until the volume fraction of water falls below 70 and 62%, respectively. The properties of the carotenoid phospholipids have been characterized by determining surface tension, critical micelle concentration, surface concentration, molecular area, free energy of adsorption and micellation, adsorption-micellar energy relationship, and equilibrium constants.

Probing drug solubilization patterns in the gastrointestinal tract after administration of lipid‐based delivery systems: A phase diagram approach

The formation of lyotropic phases resulting from the digestion of formulation lipids has a pronounced impact on the intestinal solubilization and resultant bioavailability of poorly water-soluble drugs. In this study, phase diagrams were produced to determine the phase behavior of the digestion products of common formulation lipids (C8:0, C12:0, and C18:1) under model physiological conditions. Pseudoternary phase diagrams were constructed using varying proportions of SEIF (Simulated Endogenous Intestinal Fluid) and fatty acid (FA) and monoglyceride (MG) (as representative exogenous lipid digestion products). A change from liquid crystal to colloidal liquid (containing mixed micelles and vesicles) was observed with decreasing FA/MG concentrations. The solubilization enhancement ratio (SER) afforded by these phases for a series of poorly water-soluble compounds (hydrocortisone and hydrocortisone esters, clogP = 1.4 to 5.2) was measured relative to the intrinsic solubility in buffer. Large increases in SER were observed in both lamellar (10-2000 fold) and cubic (10-30,000 fold) liquid crystal phases. Positive correlations were observed between the solubilization benefit provided by each phase and drug lipophilicity (r(2) > or = 0.9). These phase/solubility trends assist in our understanding of the mechanism by which poorly water-soluble drugs are trafficked across the intestinal colloidal species that form during the digestion of lipid-based drug delivery systems.

Anti-tumor effect of chemically synthesized sulfolipids based on sea urchin's natural sulfonoquinovosylmonoacylglycerols

We recently reported that 3'-sulfonoquinovosyl-1'-monoacylglycerol (designated A-5) extracted from sea urchin intestine was effective in suppressing the growth of solid tumors. Although the major fatty acid component of A-5 was a saturated C(16) acid, there were five other fatty acids, 14:0, 18:0, 14:1, 16:1, and 18:1, which constitute minor components of A-5. Therefore, it remains unclear as to which of these six fatty acid components of A-5 has the anti-tumor effect. In this study, we synthesized sulfolipids each containing only one of these six fatty acids and tested their cytotoxicity against tumor cells and in vivo anti-tumor effects on nude-mice bearing solid tumors of human lung adenocarcinoma cell line A-549. The IC(50) values of all products against tumor cells were more than 10(-5) M, suggesting weak cytotoxic activity compared with other chemotherapeutic compounds for cancer. On the other hand, in vivo anti-tumor assay showed that sulfoquinovosylmonoacylglycerols (SQMG) composed of 14:1 and 18:1 (designated SQMG(14:1) and SQMG(18:1), respectively) were significantly effective in suppressing the growth of solid tumors. Our data suggested that these two SQMGs had a substantial anti-tumor effect in vivo, and they are of interest as candidate drugs for anti-cancer treatment.

Acid-catalyzed plasmenylcholine hydrolysis and its effect on bilayer permeability: a quantitative study

This laboratory has previously shown (Anderson, V.C. and Thompson, D.H. (1992) Biochim. Biophys. Acta 1109, 33-42; Thompson, D.H., Gerasimov, O.V., Wheeler, J.J., Rui, Y. and Anderson, V.C. (1996) Biochim. Biophys. Acta 1279, 25-34), that plasmenylcholine (1-alk-1'-enyl-2-palmitoyl-sn-glycero-3-phosphocholine; PlsPamCho) liposomes release hydrophilic contents upon photooxidation or acid-catalyzed hydrolysis. We now report the kinetics and chemical mechanism of the acid-catalyzed reaction and its effect on calcein leakage rates. Hydrolysis of the plasmenylcholine vinyl ether linkage generates fatty aldehydes and 1-hydroxy-2-palmitoyl-sn-glycero-3-phosphocholine (lysolipid); HPLC and 1H-NMR experiments establish that the former is readily air-oxidized to fatty acids, while the latter undergoes rapid acid-catalyzed rearrangement to 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine. Lysolipid formation obeys first order kinetics, yielding observed pseudo-first order rate constants that are pH-dependent. Bimolecular hydrolysis rate constants, k(bi), have also been determined. Calcein release rates from plasmenylcholine liposomes are strongly dependent on both the dihydrocholesterol (DHC) content and the extent of PlsPamCho hydrolysis within the bilayer. DHC-free plasmenylcholine liposomes (38 degrees C, pH 2.5) require < 5% PlsPamCho hydrolysis to effect > 50% calcein release within 10 min. The presence of > or = 25 mol% DHC, however, greatly reduces the observed calcein release rate; nearly 30% PlsPamCho hydrolysis is required to effect 50% calcein release over a 70-min period in 6:4 PlsPamCho/DHC liposomes. Bacteriochlorophyll a-sensitized photooxidation of plasmenylcholine liposomes also produces fatty aldehyde and another intermediate, tentatively described as 1-formyl-2-palmitoyl-sn-glycero-3-phosphocholine, that hydrolyzes to form the 1-hydroxy lysolipid. These results have important implications for the quantitative description of lysolipid effects on membrane permeability and on the design of triggerable liposomes for drug delivery.

In vivo anti-tumour effect of 3'-sulphonoquinovosyl 1'-monoacylglyceride isolated from sea urchin (Strongylocentrotus intermedius) intestine

Extracts from sea urchin intestine were screened for new anti-tumour drugs. Four glycolipids, 3'-sulphonoquinovosyl-1', 2'-diacylglyceride (A-4), 3'-sulphonoquinovosyl-1'-monoacylglyceride (2'-lyso A-4, A-5), NeuGc(alpha)2-6Glc(beta)1-1ceramide (A-6) and HSO3-8NeuGc(alpha)2-6Glc(beta)1-1ceramide (A-7), were isolated from the intestine of sea urchin, Strongylocentrotus intermedius, and characterized by means of proton nuclear magnetic resonance spectroscopy and fast atom bombardment mass spectrometry. When tested for cytotoxic activity against tumour cells in vitro, A-5 showed significant activity, but A-4, -6 and -7 did not. In addition, the hydrophilic derivatives of A-4 or -5 had no cytotoxicity. Furthermore, the anti-tumour effects on nude mice bearing solid tumours of a human lung adenocarcinoma cell line A-549 were evaluated in vivo using A-4 and -5. As a result, A-5 was found to be significantly effective in suppressing the growth of solid tumours, whereas A-4 had no effect. Pathologically, the solid tumours showed haemorrhagic necrosis areas after treatment with A-5. In this study, we have demonstrated the anti-tumour effect of sulphonoquinovosyl-lysoglyceride (A-5), which provides important information that this sulpholipid could be a useful drug for cancer chemotherapy.

Intestinal absorption of drugs. The influence of mixed micelles on on the disappearance kinetics of drugs from the small intestine of the rat

The solubilization of the hydrophilic drugs paracetamol and theophylline, and the lipophilic drugs dantrolene, griseofulvin and ketoconazole has been determined in mixed micellar aqueous dispersions composed of 10 mM taurocholate + 5 mM oleic acid. The solubilization of dantrolene and paracetamol has also been determined in aqueous (mixed) micellar dispersions of 1 g L-1 lysophosphatidyl-choline (LPC), or taurocholate/LPC. The influence of these (mixed) micelles on the absorption of the model drugs from solution was studied in the rat chronically isolated internal loop. Absorption kinetics of the drugs were evaluated on the basis of the disappearance rate of the drug dissolved in the perfusion medium in this loop. Absorption experiments with taurocholate/oleic acid in the perfusate resulted in a reduction of the disappearance rate for the lipophilic drugs and the hydrophilic drug theophylline. This could partly be ascribed to the decreased fraction of drug free in solution as a result of its micellar solubilization for dantrolene, griseofulvin and ketoconazole, but the decrease in the disappearance rate of theophylline was unexpected. Taurocholate/oleic acid, LPC and taurocholate/LPC micelles had no effect on the disappearance of paracetamol. The disappearance rate of dantrolene in the presence of LPC alone was not altered, in spite of the decreased fraction of the drug free in solution owing to its micellar solubilization. In contrast, taurocholate/LPC micelles caused a reduction in the rate of disappearance of dantrolene, as expected according to the phase-separation model. In-vitro, taurocholate and taurocholate/LPC reduced the molecular cohesion of porcine intestinal mucus, whereas LPC alone did not exhibit an effect on the gel structure of mucus.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanism of modification of rat brain lysophospholipase A activity by cationic amphiphilic drugs

The three psychotropic cationic amphiphilic drugs, chlorpromazine, desmethylimipramine and propranolol were found to have biphasic effects on rat brain lysophospholipase A, stimulating the enzyme at low, and inhibiting it non-competitively at higher concentrations. Low concentrations (less than or equal to 50 microM) of the drugs prevented the formation of micelles of lysophosphatidylcholine, whereas high concentrations caused a phase transition of the substrate with formation of a highly ordered membranous lattice. A possible mechanism of stimulation and inhibition of the enzyme activity by cationic amphiphilic drugs is proposed. Stimulation is explained by a decrease in the concentration of substrate micelles, which are inhibitory for the activity, whereas inhibition may be caused by adsorption of the enzyme onto the membranous lattice formed by the substrate in the presence of high cationic amphiphilic drug concentrations.

Relationship of critical micelle concentrations of bacterial lipoteichoic acids to biological activities

The critical micelle concentration (CMC) of lipoteichoic acid (LTA) was investigated with two dyes, rhodamine 6G and Coomassie brilliant blue R-250. Both dyes gave similar values for the CMC of LTA. The CMC of LTA from several species of bacteria ranged from 28 to 60 micrograms/ml in phosphate-buffered saline. The CMC values for the LTAs are in the range expected for an amphiphile containing a single, 16-carbon fatty acid residue. Formation of micelles was not detected with deacylated LTA. Salt decreased the CMC of LTA from 380 micrograms/ml in distilled water to 37 micrograms/ml in 0.5 M NaCl. At concentrations greater than the CMC, LTA induced the lysis of sheep erythrocytes and was cytotoxic for Girardi heart cells. The data suggest that LTA in the micellar state may cause disruption of the erythrocyte membrane and may be cytotoxic for cells in culture.

Methods for the preparation of lysophosphatidylcholine

The surfactant and solubilizing properties of lysophosphatidylcholine (LPC) could have industrial uses if it became available in technical quantity and purity. The two most promising routes for obtaining it are isolation from cereal starches and mono-deacylation of egg phosphatidylcholine (PC). Baker's yeast autolysed by Letters's method yielded up to 0·3 % of LPC. The phospholipase A activity of pancreatin powder gave 80 % of the theoretical yield of LPC under optimum conditions; modifications designed to facilitate scale-up reduced the yield. Base-catalysed glycerolysis at 75° gave 23 % of the theoretical yield of LPC, and a reaction between PC and ethanolamine up to 45%. The crude product from ethanolamine after acetone precipitation gave an emulsifier containing LPC, PC and long-chain N-2-hydroxyethylamide.