Heat shock proteins (HSPs) are functional proteins ubiquitously expressed in all organisms. Their expression is induced by elevated temperatures and other external stress factors. Research has shown that HSPs have several functions; for example, their expression protects cells from stress-induced damage. HSPs also act as molecular chaperones that bind to newly formed proteins to mediate their folding into the correct shape, ensuring proper functioning. In addition, they function in transport activities, interact with other molecules and mediate cellular apoptosis. Since HSPs play a significant role in regulating the processes associated with cellular protection and repair, they are an important target for topical ingredients that address skin aging, repair and/or protection from damaging conditions.
HSPs are classified by their molecular weight, size, structure and function. They are divided into several families, including: HSP100, HSP90, HSP70, HSP60, HSP40 and small heat shock proteins (sHSP). Recent skin research has focused on HSP70 and HSP27, a member of the sHSPs, which are predominantly expressed in keratinocytes. HSP27 expression increases simultaneously with keratinocyte differentiation and is considered a biomarker for cellular turnover in the epidermis. HSP70 helps to prevent melanocytes from undergoing apoptosis and since melanocytes protect cells from UV exposure, this could prevent skin damage caused by UV exposure.
Lab Practical: Formulating with Salicin
- Salicin is a water-soluble white powder that can be employed in various aqueous delivery systems in gels, emulsions and suspensions.
- Levels other than 0.5% have not been validated to deliver the benefits detailed in the present research.
- Salicin is stable in its natural form and in solution; it has a shelf life of two years.
- Salicin is not self-preserved. As such, Gram-negative and Gram-positive preservation systems are recommended for salicin-containing formulations.
- The addition of glycols is also recommended for increased efficacy and stability.