Effect of oral contraceptives on sebum excretion rate.

Oral contraceptives containing a high dose of oestrogen reduce the sebum excretion rate (SER) and improve acne vulgaris, but more progestogenic preparations may exacerbate acne. The effect on the SER of several oral contraceptives with varying progestogenic potencies was studied in 81 women. The predominantly progestogenic pills (Eugynon 30, Gynovlar) produced no significant change in SER, whereas the rate in women taking a more oestrogenic pill (Minovlar) was significantly reduced compared with the rate in controls. Progestogens therefore do not exacerbate acne by inducing seborrhoea, but in the doses we studied they nullified the inhibitory effect of oestrogens on the sebaceous glands. Acne-prone women who require an oral contraceptive should be given a predominantly oestrogenic preparation.     

Lipophilic antioxidants in human sebum and aging

Skin surface lipids (SSL), a very complex mixture of sebum mixed to small amounts of epidermal lipids, mantle the human epidermis, thus representing the outermost protection of the body against exogenous oxidative insults. The present work is a systematic and quantitative analysis of upper-chest SSL and their content in antioxidants in 100 healthy volunteers, divided into five age groups using TLC, HPLC, and GC-MS methods. Further, the effect of exposing SSL in vitro to increasing doses of UV irradiation was examined. Straight monounsaturated and diunsaturated as well as branched monounsaturated fatty acids of triglycerides and pooled fractions were found to be higher at maturity than in childhood and in advancing age. Diunsaturated fatty acids were below 3% of the total and constituted exclusively of C18:2 Δ5,8 , C20:2 Δ7,10 , C18:2 Δ9,12 . Squalene, vitamin E (vit. E) and Coenzyme Q 10 (CoQ 10 ) were found to increase from childhood to maturity to decrease again significantly in old age. Vitamin E and CoQ 10 were the only known lipophilic antioxidants present in SSL. In spite of their low levels they were found to synergically inhibit the UV induced depletion of squalene, cholesterol and of unsaturated fatty acids of SSL. In fact, exposure of SSL to increasing amounts of UV irradiation led preferentially to lowering of the levels of vit. E and CoQ 10 . Four minimal erythema dose (MED) (5.6 J/cm 2 ) were able to deplete 84% vit. E and 70% ubiquinone, and only 13% squalene. Diunsaturated and monounsaturated fatty acids as well as cholesterol were unaffected even following 10 MED UV exposures, which produced a 26% loss of squalene. The same UV dose when applied in the absence of vit. E and CoQ 10 produced a 90% decrease of squalene.     

The time course of sebum secretion in the guinea-pig

The time course of sebum secretion in the guinea-pig (Cavia porcellus) was determined by intradermal injection of [1-14C]acetate followed by daily collection of the skin surface lipids at the injection site. The skin surface lipids reached a peak of radioactivity at 5-6 days, indicating that this is the time which elapses between the synthesis of sebum and the surface excretion of the sebaceous lipids. Of the three major skin surface lipid components, the sterol esters (25%) and the wax diesters (25%) showed similar peaks of radioactivity after labelling, but the glycerol ether diesters (30%) showed no radioactivity at any time, suggesting that this lipid is not produced in the skin.     

Quantitative evaluation of sebum lipid components with nuclear magnetic resonance

A NMR spectroscopic method is described that enables the quantitation of specific lipid classes and components, independent of fatty acid composition. We demonstrate this method for measuring cholesterol, squalene, and pools of sterol esters, wax esters (WEs), and triglyceride (TG) components in sebum and meibum. When 600 MHz NMR equipment is used in conjunction with highly sensitive cryogenically cooled probes, this method has adequate sensitivity, and for some applications, advantages over commonly used HPLC-evaporative light-scattering detection and mass spectrometry-based approaches. This method is shown to be useful for preclinical and clinical monitoring of the efficacy of sebum-reducing agents in animals and humans. In Syrian hamsters, 3% topical flutamide and 20 mg/kg oral isotretinoin reduced sterol esters by 18.7% and 30.0%, respectively, and reduced WEs by 32.9% and 31.8%, respectively, as measured in a punch biopsy of the ear. In a 72 patient clinical methodology study, the assay delivered reproducible and noninvasive measurements of WEs, cholesteryl esters, TGs, and squalene from Sebutape skin blots. The quantitative results of sebum analysis obtained by the NMR method correlate well with those obtained with HPLC-based approaches. This approach may be broadly applicable to cases in which fatty acid-independent quantification of lipid classes is desired.     

Lack of influence of testosterone on sebum output and composition in bovines

Experiments were conducted to determine if testosterone influences sebum output (SO) and composition (SC) in different genotypes of cattle. There were significant breed differences in plasma testosterone levels and SO but no relationship was established between the two variables. Castration of neonatal and adult bulls did not affect their subsequent SO or SC. Testosterone treatment of steers failed to change SO. There were no differences in SO or SC between bulls and heifers. The results showed that testosterone does not influence sebum production in bovines and that there was a strong genetic control over SO independent of sex.     

Liquid chromatographic analysis of sebum lipids and other lipids of medical interest

A technique is described for the high-pressure liquid chromatographic (HPLC) analysis of sebum lipid classes. The lipid classes present in sebum are separated by gradient elution HPLC from a microparticulate silica column and detected using a moving-wire detector. The system described can be linked to a computer. Quantitation can be carried out by comparing peak areas obtained with those of an internal standard. Peak trapping for further investigations of the separated components, for example by gas chromatography—mass spectrometry, is very easy.Sebum lipids are separated into the following lipid classes: hydrocarbons and squalene, cholesterol esters and wax esters, fatty acids as their methyl esters, triglycerides, 1,3-diglycerides, 1,2-diglycerides, free cholesterol, monoglycerides and other polar materials. Besides to sebum, the method has been successfully applied to other lipid mixtures, such as serum lipids. Examples of other applications are shown.     

Pantolactams as androgen receptor antagonists for the topical suppression of sebum production

A series of pantolactam based compounds were identified as potent antagonists for the androgen receptor (AR). Those that possessed properties suitable for topical delivery were evaluated in the validated Hamster Ear Model. Several compounds were found to be efficacious in reducing wax esters, a major component of sebum, initiating further preclinical work on these compounds.