GlycerinvsSqualane

Glycerin (glycerol) is a small three-carbon polyol (92 Da) that penetrates the stratum corneum via intercellular lipid and transcellular routes. It acts as a humectant through osmotic mechanisms—creating a concentration gradient that draws water from the atmosphere (when humidity >65%) and from deeper epidermal layers. Glycerin upregulates aquaporin-3 (AQP3), a glycerol-permeable water channel in keratinocyte membranes that facilitates water and glycerol transport. It supports the natural moisturizing factor (NMF)—amino acids, lactate, and urea that maintain stratum corneum water-holding capacity. Glycerin modulates keratinocyte differentiation and may enhance lipid lamellae organization. Mild antimicrobial activity occurs through osmotic stress. Clinical studies demonstrate hydration efficacy comparable to or exceeding hyaluronic acid.

Squalane is the fully hydrogenated form of squalene—a C30 isoprenoid hydrocarbon. As a saturated branched-chain hydrocarbon, squalane forms a non-occlusive emollient film that fills intercellular lipid spaces and reduces transepidermal water loss (TEWL) by approximately 20-30%. Squalene comprises ~12% of human sebum (synthesized via mevalonate pathway); squalane's structural similarity confers high biocompatibility and minimal comedogenic potential. Hydrogenation of squalene's six double bonds eliminates oxidative susceptibility—squalene peroxidizes with UV exposure while squalane remains stable. Squalane penetrates the stratum corneum and may support barrier lipid organization. Plant-derived squalane (sugarcane, olive) is structurally identical.