In vitro skin penetration of petrolatum and soybean oil and effects of glyceryl monooleate.

OBJECTIVES: Petrolatum and soybean oil are common ingredients incorporated in topical skin formulations for skin protection and moisturization. However, the stratum corneum (SC) penetration kinetics of these two cosmetic ingredients has not been systematically studied. Glyceryl monooleate (GlyMOle) has been shown to enhance skin penetration of various compounds. It was hypothesized that GlyMOle could enhance skin penetration of petrolatum and soybean oil. This study aimed to examine the in vitro skin penetration of petrolatum and soybean oil in the presence or absence of GlyMOle. METHODS: Skin permeation experiments were conducted using the in vitro Franz diffusion cell model with split-thickness human skin and human epidermal membrane (HEM). The effect of permeant dose and the kinetics of permeant penetration were examined with and without GlyMOle in vitro. RESULTS: Petrolatum and soybean oil were found to permeate across HEM, and no effect of GlyMOle on skin permeation into the receptor chamber was observed. GlyMOle enhanced the penetration of petrolatum into the split-thickness skin at 50 µg dose (petrolatum:GlyMOle, 49 : 1, w/w). However, no effect of GlyMOle on petrolatum penetration was observed at 200 µg dose (of the same petrolatum:GlyMOle ratio), indicating a dose-dependent effect. GlyMOle at the level used in the study did not enhance the penetration of soybean oil with 50 and 200 µg doses at any timepoints. CONCLUSION: GlyMOle was a skin penetration enhancer for petrolatum under the in vitro conditions identified in this study.

Gel network shampoo formulation and hair health benefits.

OBJECTIVE: The objective of this work was to create a shampoo formula that contains a stable ordered gel network structure that delivers fatty alcohols inside hair. METHODS: X-ray diffraction (SAXS and WAXS), SEM and DSC have been used to confirm formation of the ordered Lß gel network with fatty alcohol (cetyl and stearyl alcohols) and an anionic surfactant (SLE1S). Micro-autoradiography and extraction methods using GC-MS were used to confirm penetration of fatty alcohols into hair, and cyclic fatigue testing was used to measure hair strength. RESULTS: In this work, evidence of a stable Lß ordered gel network structure created from cetyl and stearyl alcohols and anionic surfactant (SLE1S) is presented, and this is confirmed via scanning electron microscopy images showing lamella layers and differential scanning calorimetry (DSC) showing new melting peaks vs the starting fatty alcohols. Hair washed for 16 repeat cycles with this shampoo showed penetration of fatty alcohols from the gel network into hair as confirmed by a differential extraction method with GC-MS and by radiolabelling of stearyl alcohol and showing its presence inside hair cross-sections. The gel network role in delivering fatty alcohol inside hair is demonstrated by comparing with a shampoo with added fatty alcohol not in an ordered gel network structure. The hair containing fatty alcohol was measured via the Dia-stron cyclic fatigue instrument and showed a significantly higher number of cycles to break vs control. CONCLUSIONS: The formation of a stable gel network was confirmed in the formulated shampoo, and it was demonstrated that this gel network is important to deliver cetyl and stearyl alcohols into hair. The presence of fatty alcohol inside hair was shown to deliver a hair strength benefit via cyclic fatigue testing.

Preserving fibre health: reducing oxidative stress throughout the life of the hair fibre.

Hair health is an important attribute to women globally--specifically attributes such as shine, healthy tips, frizz-free and strength. However, many women will claim to have at least moderate hair damage caused by habits and practices such as washing, combing and brushing, use of heated implements and regular use of chemical treatments. The objective of this work was to investigate two mechanisms of damage--hair colouring and UV exposure--where oxidative processes are involved. The role of copper in these oxidative processes was then investigated: its presence in hair and its consequent impact on hair damage via free radical formation. Finally, the role of chelants N,N'-ethylene diamine disuccinic acid (EDDS) and histidine in preventing free radical formation was investigated and shown to improve hair health.

The direct glucuronidation of 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) by human and rabbit liver microsomes.

The glucuronidation of the food-borne heterocyclic amine 2-amino-1-methyl-6-phenylimidazo-[4,5-b]pyridine (PhIP) was investigated using hepatic microsomes from several species. PhIP-glucuronic acid conjugates were formed in an NADPH-free system using microsomes from rabbit, dog, guinea pig, and human. Rat, hamster, and mouse microsomes were incapable of directly producing PhIP-glucuronides. The PhIP-glucuronide generated with human microsomes could be resolved by reverse-phase HPLC from that produced with rabbit microsomes. In addition, the human PhIP-glucuronide was susceptible to enzymatic hydrolysis by beta-glucuronidase, whereas the rabbit PhIP-glucuronide did not undergo beta-glucuronidase catalyzed hydrolysis. Fast atom bombardment mass spectrometry of both glucuronides revealed the presence of ions with m/z 401 (M+H+). Rabbit PhIP-glucuronide had a lambda max of 316 nm, similar to that of the parent PhIP. By contrast, a spectral shift in UV absorbance was observed for the human PhIP-glucuronide, which had a lambda max of 305 nm. 1H-NMR spectroscopy and nuclear Overhauser enhancements established that rabbit PhIP-glucuronide was conjugated at the exocyclic amine nitrogen, whereas human PhIP-glucuronide was conjugated at the N3 imidazole ring nitrogen. Km values for PhIP were 0.2-0.3 mM in both species; however, rabbit microsomes exhibited a 22-fold higher Vmax. Collectively, these studies indicate that human and rabbit liver microsomes form structurally different glucuronides of PhIP and suggest the involvement of multiple isoforms of UDP-glucuronosyltransferase. Further, these data suggest that in certain species, including humans, the direct conjugation of PhIP with glucuronic acid may represent a primary route of PhIP metabolism and detoxication.

Studies on tertiary amine UDP-glucuronosyltransferases from human and rabbit hepatic microsomes.

The conversion of tertiary amines to quaternary ammonium glucuronides was investigated in human liver microsomes, and characteristics of the UDP-glucuronosyltransferase (UGT) catalyzing quaternary ammonium glucuronidation were evaluated. In addition, a rabbit liver microsomal UGT mediating this reaction was studied. The kinetics of quaternary ammonium glucuronidation of cyproheptadine, tripelennamine, amitriptyline, and doxepin in intact human liver microsomes was determined. Tripelennamine was found to have the lowest apparent KM and was used as a representative substrate for further studies. A polyclonal antibody preparation raised in sheep against rabbit liver p-nitrophenol UGT was found to inhibit tripelennamine glucuronidation in solubilized human liver microsomes, but had no effect on p-nitrophenol, 4-methylumbelliferone, 4-aminobiphenyl, estriol, morphine, or naloxone glucuronidation. This antibody also inhibited tripelennamine glucuronidation in solubilized rabbit liver microsomes, but had little or no effect on estrone, testosterone, estradiol, androsterone, and morphine glucuronidation. Chlorpromazine competitively inhibited tripelennamine glucuronidation. This inhibition was markedly enhanced by UV light irradiation. [3H] Chlorpromazine binding to solubilized human liver microsomes was also increased by UV light. The binding was antagonized by substrates for tertiary amine UGT but not by substrates for morphine UGT. These studies suggest that the tertiary amine UGT is photo-affinity-labeled by chlorpromazine. Furthermore, it would appear from immunoinhibition and [3H]chlorpromazine labeling experiments that tertiary ammonium glucuronidation is catalyzed by a unique and distinct UGT in rabbit and human liver microsomes.

Cloning and expression of a rat liver phenobarbital-inducible UDP-glucuronosyltransferase (2B12) with specificity for monoterpenoid alcohols.

A full-length cDNA, HBPA2, that encodes for a new rat hepatic UDP-glucuronosyltransferase protein, designated UGT2B12, was isolated from a rat liver cDNA library. The isolated clone contains a 1590-nucleotide open reading frame flanked by 2 and 252 base pairs of 5' and 3' noncoding sequences, respectively. Human embryonic kidney 293 cells transfected with UGT2B12 expressed a protein with a subunit molecular mass of 53 kDa. The expressed protein catalyzed the glucuronidation of monoterpenoid alcohols, such as (-)-borneol, (+)-menthol, and (-)-nopol. In addition, a number of simple phenolic compounds, such as hydroxybiphenyls, 7-hydroxylated coumarins, p-nitrophenol, and food-derived substances (e.g., naringenin and eugenol), were also substrates for the expressed enzyme. Northern blot analysis showed that treatment of rats with phenobarbital increased hepatic mRNA levels for UGT2B12 approximately twofold. In addition to liver, Northern blot analysis demonstrated that UGT2B12 mRNA is present in kidney and testis.