Kimberly Wade

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.

Comparison of artificial sebum with human and hamster sebum samples.

To understand drug delivery to the sebum filled hair and sebaceous follicles, it is essential to use an artificial sebum as a surrogate of the human sebum for the investigation of drug transport properties. Artificial sebum L was developed in-house based on the chemical similarity to human sebum. The partition and diffusion of model compounds (ethyl 4-hydroxybenzoate, butyl 4-hydroxybenzoate, and hexyl 4-hydroxybenzoate) were measured in human sebum, hamster ear and body sebum (a commonly used animal model), and four representative artificial sebum samples (N, S, F, and L) in which artificial sebums, N, S and F were selected based on the available literature. DSC and NMR studies were also conducted on all sebums to compare their melting properties and chemical compositions. In vitro studies show that the partition coefficients of the three model compounds in artificial sebum L were similar to that of human sebum, whereas the hamster ear and body sebum, and other three artificial sebum samples were different from that of human sebum. Additionally, the in vitro sebum flux (microg/(cm(2)min) of three model compounds through artificial sebum L was closer to that of human sebum when compared with the other three artificial sebum (N, S and F), hamster body and hamster ear sebum. The results of this study indicate that the artificial sebum L could be used as an alternative to human sebum, as the physicochemical properties of this artificial sebum is relatively similar to human sebum.

Rational design and synthesis of 4-((1R,2R)-2-hydroxycyclohexyl)-2(trifluoromethyl)benzonitrile (PF-998425), a novel, nonsteroidal androgen receptor antagonist devoid of phototoxicity for dermatological indications.

4-((1 R,2 R)-2-Hydroxycyclohexyl)-2(trifluoromethyl)benzonitrile [PF-0998425, (-)- 6a] is a novel, nonsteroidal androgen receptor antagonist for sebum control and treatment of androgenetic alopecia. It is potent, selective, and active in vivo. The compound is rapidly metabolized systemically, thereby reducing the risk of unwanted systemic side effects due to its primary pharmacology. (-)- 6a was tested negative in the 3T3 NRU assay, validating our rationale that reduction of conjugation might reduce potential phototoxicity.

4-(Alkylthio)- and 4-(arylthio)-benzonitrile derivatives as androgen receptor antagonists for the topical suppression of sebum production

The first examples of thioether-substituted benzonitriles as potential soft-drug androgen receptor antagonists are reported. A number of 4-(alkylthio)- and of 4-(arylthio)-benzonitrile analogs were evaluated in human androgen receptor binding and cellular functional assays. Analogs with potent in vitro binding and cellular activities were evaluated for topical in vivo efficacy in the Golden Syrian hamster ear model. Analogs from both the 4-(alkylthio)- and of 4-(arylthio)-benzonitrile series showed moderate reduction of wax esters in vivo.

Diphenyl ethers as androgen receptor antagonists for the topical suppression of sebum production

A series of diphenyl ethers was prepared and evaluated for androgen receptor antagonist activity in human androgen receptor binding and cellular functional assays. Analogs with potent in vitro activities were evaluated for topical in vivo efficacy in the Golden Syrian Hamster ear model. Several compounds showed reduction in wax esters in this validated animal model.

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.