Testing of glyceryl monoesters for their antimicrobial susceptibility and their influence in emulsions.

Natural anti-microbial agents have received great attention in the cosmetic preservation area due to their well-documented safety profile. The anti-microbial activities of palm-based glyceryl monoesters (monolaurin, monocaprylin and monocaprin) were compared with commercially available tea tree oil and potassium sorbate against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Aspergillus niger, using the anti-microbial susceptibility testing procedure. Monolaurin was found to exhibit excellent inhibitory activity against S. aureus and Asp. niger, whereas potassium sorbate and tea tree oil had no activity against Asp. niger and S. aureus, respectively. Monocaprylin was shown to have low inhibitory activity against E. coli, and no inhibitory activity towards P. aeruginosa. On the other hand, tea tree oil had a higher inhibitory activity than monolaurin at 2% against E. coli but showed no activity against P. aeruginosa. Similar trends were observed for monocaprin and monolaurin which showed no anti-microbial activity towards P. aeruginosa as well as E. coli. Interestingly, the presence of monolaurin was not only effective as a preservative, but was also found to induce the formation of liquid crystals at concentrations as low as 0.5%. The formation of liquid crystals is said to enhance the stability and functionality of cosmetic emulsions

Effect of compositions in nanostructured lipid carriers (NLC) on skin hydration and occlusion.

Purpose: To study the effects of varying lipid concentrations, lipid and oil ratio, and the addition of propylene glycol and lecithin on the long-term physical stability of nanostructured lipid nanocarriers (NLC), skin hydration, and transepidermal water loss. Methods: The various NLC formulations (A1-A5) were prepared and their particle size, zeta potential, viscosity, and stability were analyzed. The formulations were applied on the forearms of the 20 female volunteers (one forearm of each volunteer was left untreated as a control). The subjects stayed for 30minutes in a conditioned room with their forearms uncovered to let the skin adapt to the temperature (22°C±2°C) and humidity (50%±2%) of the room. Skin hydration and skin occlusion were recorded at day one (before treatment) and day seven (after treatment). Three measurements for skin hydration and skin occlusion were performed in each testing area. Results: NLC formulations with the highest lipid concentration, highest solid lipid concentration, and additional propylene glycol (formulations A1, A2, and A5) showed higher physical stability than other formulations. The addition of propylene glycol into an NLC system helped to reduce the particle size of the NLC and enhanced its long-term physical stability. All the NLC formulations were found to significantly increase skin hydration compared to the untreated controls within 7 days. All NLC formulations exhibited occlusive properties as they reduced the transepidermal water loss within 7 days. This effect was more pronounced with the addition of propylene glycol or lecithin into an NLC formulation, whereby at least 60% reduction in transepidermal water loss was observed. Conclusion: NLCs with high lipid content, solid lipid content, phospholipid, and lecithin are a highly effective cosmetic delivery system for cosmetic topical applications that are designed to boost skin hydration

An improved method for the preparations of nanostructured lipid carriers containing heat-sensitive bioactives.

Heat-sensitive bioactive compounds such as β-carotene and tocols, are widely used in the pharmaceutical and cosmetic fields. Their chemical stability in delivery systems is one of the major concerns in the production of nanostructured lipid carriers (NLCs). A previously established high-temperature high-pressure homogenisation technique involved in the preparation of NLCs can cause degradation of heat-sensitive compounds. Therefore, a novel preparation process needs to be developed to minimise the degradation of heat-sensitive active compounds during the preparation of NLCs. In this work, modified methods A and B were designed to minimise the degradation of β-carotene and tocols during the production of NLCs. These methods improved the chemical stability of heat-sensitive bioactive compounds (β-carotene and tocols) significantly compared to the previously established method. The physical stability of the formulation was maintained throughout study duration

Nanostructured lipid carriers (NLC) for efficient delivery of palm phytonutrients

Palm phy­tonu­tri­ents found in crude palm oil con­sist of carotenes and tocols as well as other minor com­po­nents includ­ing sterols, squa­lene, ubiquinones, coen­zyme Q10 and phos­pho­lipids. Palm phy­tonu­tri­ents con­tains all the nat­u­rally occur­ring phy­tonu­tri­ents present in crude palm oil, whereas com­mer­cially avail­able indi­vid­ual phy­tonu­tri­ents, such as Gold-tri E and Tocomin 50% mainly con­sist of palm tocotrienols. The encap­su­la­tion of palm phy­tonu­tri­ents by nanos­truc­tured lipid car­ri­ers (NLC) was inves­ti­gated using Trans­mis­sion Elec­tron Microscopy. NLC was proven to effec­tively encap­su­late palm phy­tonu­tri­ents in oil droplets. Based on the par­ti­cle size analy­sis and rhe­o­log­i­cal study, NLC was found to be the most phys­i­cally sta­ble deliv­ery sys­tem when com­pared to the macro-emulsion and the nano-emulsion car­ri­ers. The long-term chem­i­cal sta­bil­ity of the palm phy­tonu­tri­ent using β-carotene as the pro­to­type active in NLC was also deter­mined. The degra­da­tion of β-carotene in NLC was lower when com­pared to the macro-emulsion and the nano-emulsion car­ri­ers. The effi­cacy of NLC as a deliv­ery sys­tem and the effect of the addi­tion of lecithin and propy­lene gly­col to the NLC for­mu­la­tion were also stud­ied. The para­me­ters inves­ti­gated were skin hydra­tion and trans-epidermal water loss (TEWL). NLC with the pres­ence of 1% lecithin and 2% propy­lene gly­col were found to enhance skin hydra­tion and pre­vent water loss

Study protocol: How does cognitive flexibility relate to other executive functions and learning in healthy young adults?

BackgroundCognitive flexibility (CF) enables individuals to readily shift from one concept or mode of practice/thoughts to another in response to changes in the environment and feedback, making CF vital to optimise success in obtaining goals. However, how CF relates to other executive functions (e.g., working memory, response inhibition), mental abilities (e.g., creativity, literacy, numeracy, intelligence, structure learning), and social factors (e.g., multilingualism, tolerance of uncertainty, perceived social support, social decision-making) is less well understood. The current study aims to (1) establish the construct validity of CF in relation to other executive function skills and intelligence, and (2) elucidate specific relationships between CF, structure learning, creativity, career decision making and planning, and other life skills.MethodsThis study will recruit up to 400 healthy Singaporean young adults (age 18-30) to complete a wide range of cognitive tasks and social questionnaires/tasks. The richness of the task/questionnaire battery and within-participant administration enables us to use computational modelling and structural equation modelling to examine connections between the latent constructs of interest.Significance and impactThe current study is the first systematic investigation into the construct validity of CF and its interrelationship with other important cognitive skills such as learning and creativity, within an Asian context. The study will further explore the concept of CF as a non-unitary construct, a novel theoretical proposition in the field. The inclusion of a structure learning paradigm is intended to inform future development of a novel intervention paradigm to enhance CF. Finally, the results of the study will be useful for informing classroom pedagogy and the design of lifelong learning policies and curricula, as part of the wider remit of the Cambridge-NTU Centre for Lifelong Learning and Individualised Cognition (CLIC)