Straight chain 1,2-alkanediols have been used for more than 15 years as moisturizers with multifunctional activities.1–3 In fact, pentylene glycol, also known as 1,2-pentanediol, was the first of the 1,2-alkanediols introduced to the cosmetic industry in the early 1990s. Since then, 1,2-hexanediol (see Figure 1a); caprylyl glycol also known as 1,2-octanediol (see Figure 1b); and more recently, decylene glycol or 1,2-decanediol, also have become available in the personal care industry.
Short chain 1,2-alkanediols are amphiphilic compounds and thus, like 1,2-pentanediol and 1,2-hexanediol, are soluble both in water and cosmetic esters. On the other hand, 1,2-decanediol is a solid and soluble only in cosmetic esters. Apart from moisturizing and anti-microbial activities, some 1,2-alkanediols are used as solvents for various cosmetic actives and viscosity modifiers.
The present research reports the results of studies on the anti-microbial properties of straight chain 1,2-alkanediols, mixtures of them, and combinations of 1,2-alkanediols with other preservatives and antimicrobial compounds. Here, the authors evaluate the potential of 1,2-alkanediols for use as preservative boosters to reduce the levels of preservatives required in formulations. In addition, the authors discuss formulating with 1,2-alkanediols to optimize formulations for stability and efficacy.