Black Truffle, Nanocrystals and Flexible Films: Recent Literature Findings

By: Charles Fox, Charles Fox Associates

Posted: October 30, 2008, from the November 2008 issue of Cosmetics & Toiletries.

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Ascorbyl palmitate nanocrystals for nanosuspension: Teeranachaideekul et al. have published on the development of ascorbyl palmitate nanocrystals for nanosuspension.¹² Ascorbyl palmitate (AP) is an antioxidant used in both the cosmetics and foods industries. Owing to its poor solubility and instability caused by oxidation, the aim of this study was to investigate the feasibility of applying the nanosuspension technology by high-pressure homogenization (HPH) to enhance the chemical stability of AP, followed by lyophilization.

Sodium dodecyl sulfate (SDS) and polysorbate 80 were chosen as emulsifying agents to stabilize the AP nanosuspensions. After three months of storage at 4°C, 25°C and 40°C, the photon correlation spectroscopy (PCS) analysis of AP nanosuspensions revealed that the mean particle size of those formulations stabilized with SDS significantly increased, as compared with those formulas stabilized with polysorbate 80. The results from both atomic force microscopy and SEM revealed AP nanocrystals with a cubic-like shape. The percentage of AP remaining in nanosuspensions stabilized with polysorbate 80 was higher than 90% after the three months of storage at 4°C, 25°C and 40°C.

To increase the chemical stability of AP nanosuspensions, a drug powder was prepared by lyophilization. The effect of the cryoprotectant trehalose on the physical stability was evaluated at different concentrations. After redispersing the lyophilized product, the mean size of AP nanosuspensions without trehalose was found to be significantly higher than those including trehalose. After three months of storage at 25°C, the mean size of lyophilized AP nanosuspensions remained constant. X-ray diffraction revealed the crystal character of AP nanocrystals after HPH and lyophilization.

Interesting New Vehicles/Formulations

Phospholipid, sphingosine derivatives in vesicle compositions: Kosei Co., Ltd., discloses vesicle compositions containing phospholipid and sphingosine derivatives, and skin compositions containing the same.¹³ The vesicle composition reportedly excels in skin permeability and storage stability without causing discoloration or odor. It has been shown to be suitable in a skin composition wherein the vesicle composition contains: at least one phospholipid derivative containing an unsaturated fatty acid residue in the second acyl group, and at least one sphingosine derivative. The vesicle composition may further contain cholesterol and/or phytosterol.

In a disclosed formula containing the vesicle composition (see Formula 9), hydrogenated soybean phosphatidylcholine was treated with phospholipase A2 to give 1-acyl-2-lysophosphatidylcholine, and further treated with oleic anhydride to obtain 1-acyl-2-oleoyl-3-phosphatidylcholine. The formula included 40 parts of the vesicle composition with other ingredients to create a cosmetic lotion.