The effectiveness of molecular oxygen in cosmetic formulations.

Synopsis In a preliminary clinical study, two cosmetic preparations were compared, one without an oxygen carrier and therefore without oxygen, the other one containing the oxygen carrier, fully saturated with oxygen. The parameters measured were the moisture content of the skin and the skin profile. Since the oxygen-free product contained the same ingredients, including phospholipids in liposomal form, with the exception of perfluorodecalin - the oxygen carrier, this investigation showed that perfluorodecalin plus molecular oxygen improves the barrier function of the skin. In a second clinical study, five cosmetic preparations containing various amounts of molecular oxygen from 1.44 ml to 4.5 ml per 100 ml product were compared. The parameters measured were the oxygen partial pressure of the skin, the moisture content of the skin, and the skin profile. A linear dose-dependent increase in oxygen partial pressure of the skin (r=0.978) and a linear dose-dependent reduction in fine lines and wrinkles (r=0.9855) was found. The results for the increase in skin moisture were more difficult to interpret. There seemed to be an overlap of the moisturizing base with the efficacy coming from the increasing amount of oxygen per application.

Enhancement of the penetration of dithranol and increase of effect of dithranol on the skin by liposomes.

An assessment was made in healthy skin of dithranol erythema caused by a 10-min occlusive application of 0.5% dithranol (CAS 1143-38-0) in liposomal gel (Natipide II) with and without the addition of 3% salicylic acid, and of 0.5% dithranol in vaseline and in a removable standard ointment base, both with 3% salicylic acid. Both liposomal preparations led to a significant potentiation of the dithranol erythema. The results indicate a strong promotion of the penetration of dithranol by the liposomal gel.

Increase of lipid fluidity and suppression of proliferation resulting from liposome uptake by human keratinocytes in vitro.

The in vitro effects of liposomes on HaCaT human keratinocytes were studied with regard to their uptake, lipid fluidity and proliferation of the cells. Oligolamellar liposomes, prepared from soya bean phospholipids, had a mean size of 150 mm and consisted predominantly of phosphatidylcholine (83%) and phosphatidylethanolamine (10%) and the fatty acids comprised mainly linoleic acid (66%) or other unsaturated fatty acids. After 6 and 24 h of incubation with 1 and 0.1% w/v of liposomal lipids, phase-contrast microscopy revealed marked cytoplasmic vacuolization of the cells. Keratinocytes treated with the liposomes contained aggregations of multilaminated lipid material without delimiting cell membranes. The cellular lipid fluidity (reciprocal of diphenylhexatriene fluorescence polarization P-value) correlated with liposomal concentration and incubation time. A significant elevation of lipid fluidity (P less than 0.05) was observed with 1 and 0.1% liposomes after 1 h of incubation (81.8 +/- 4.7 and 95.7 +/- 1.2% of control P value) and for 0.01% liposomes after 3 h (96.2 +/- 1.5%). Maximum fluidity occurred after 48 h of exposure to 1% liposomes (42.1 +/- 3.1%). Exposure to liposomal lipids for 24 and 48 h resulted in suppressed cell proliferation with 50% inhibition concentrations (IC50), being 0.06% for incorporation of [3H]-thymidine. 0.08% for [14C]-amino-acid incorporation and greater than 1% for protein content per well after 24 h of exposure. The cells were able to proliferate and lipid fluidity returned to normal within 7 days following discontinuation of incubation with liposomal lipids.

Liposomes from soya phospholipids as percutaneous drug carriers. 1st communication: qualitative in vivo investigations with antibody-loaded liposomes.

The penetration behaviour of liposome (prepared from NAT 106)-incorporated proteins was investigated in vivo by use of monoclonal antibodies (MOAB) as model substances on the skin of young pigs. Within 20 min of topical application, an even distribution of liposome-incorporated antibodies through all skin layers could be shown by means of an immunohistochemical stain.

Significance of empty liposomes alone and as drug carriers in dermatotherapy.

The influence of three different liposome formulations (NAT 106, NAT 50, NAT 89), as empty liposomes and loaded with 0.05% betamethasone, on blood circulation in the corium was investigated by means of laser Doppler flowmetry. All three empty liposomes brought about a decrease in circulation. The maximum effect was reached 90 min after a 30-min occlusive application of the test preparations. Loading with betamethasone resulted in a significant increase in circulation after only 15 min. This increase in interpreted as a steroid effect. No comparable symptoms appeared with the application of base cream DAC (an O/W emulsion) or of betamethasone in base cream under identical experimental conditions.

Liposomes from soya phospholipids as percutaneous drug carriers. 2nd communication: quantitative in vivo investigations with radioactively labelled liposomes.

The percutaneous absorption of liposomes (prepared from NAT 106) was investigated with radioactively labelled substances in comparison with percutaneous absorption without liposomes (controls) in vivo on the skin of young pigs. Radioactivity was monitored as a function of time in skin tissue, plasma or blood and in urine. Elevated tissue levels, increased absorption and renal elimination of the various liposomal preparations in comparison to the controls were measured.

Effects of ethidium bromide, tetramethylethidium bromide and betaine B on the ultrastructure of HeLa cell mitochondria in situ. A comparative binding study.

Several investigators have described the ultrastructural changes that occur in the mitochondria of cells in tissue cultures after treatment with the drug ethidium bromide (E). The mitochondria swell and the cristae become greatly altered and finally disappear; in the cristae-free region of the matrix electron-dense granules can be observed. It has been assumed that intercalation of E between the base pairs of the mitochondrial DNA induces the formation of the granular inclusions. To investigate whether intercalation is really the initial step in the generation of dense granules inside the matrix, we performed a comparative incubation study of HeLa-cell mitochondria in situ using three closely related dyes (D), i.e., E, tetramethylethidium bromide (TME) and betaine B (B). They strongly differ with regard to their affinity for DNA and their ability to cross membranes. E was used as a reference dye. TME does not intercalate, but is externally bound to DNA only weakly. The neutral B is not bound at all, but can cross membranes more easily than the cation E. Moreover, in aqueous solutions at pH approximately equal to 7.0, B is in equilibrium with its protonated cation BH. BH and E have almost equal affinities for DNA. Therefore B may quickly pass the inner mitochondrial membranes and the cristae, and should then be bound inside the matrix, thus forming a BH-DNA complex. On the assumption that intercalation is necessary for the generation of intramitochondrial electron-dense bodies, we predicted that BH/B should be more efficient than E, while TME should be relatively ineffective.(ABSTRACT TRUNCATED AT 250 WORDS)