SKIN CARE 39
How ascorbic acid derivatives overcome stability challenges
Shiqi Wang, Yoshiteru Agari, Daichi Iwasaki – Seiwa Kasei
Ascorbic acid (AsA), commonly known as vitamin C, is a widely used ingredient in cosmetic formulations due to its multiple skin benefits. One of the most well-known effects is its ability to brighten the skin and even out pigmentation. It could inhibit tyrosinase, an enzyme involved in melanin production. This makes ascorbic acid a common ingredient in brightening formulations, often used to address issues such as hyperpigmentation, dark spots, and uneven skin tone. Beyond its brightening effects, ascorbic acid
acts as a coenzyme in enzyme reactions, such as collagen synthesis, a process essential for maintaining skin firmness and elasticity.1 By enhancing collagen production, it helps
to reduce the appearance of wrinkles and fine lines, contributing to a firmer, more youthful complexion. Regular use of ascorbic acid in skin care can enhance skin resilience and prevent skin ageing. In addition, as a potent antioxidant, that acts
by protecting the skin of the reactive oxygen species (ROS). When the skin is exposed to UV light, ROS are generated. Ascorbic acid protects the skin from oxidative stress by effectively neutralizing free radicals produced by UV exposure, pollution and other environmental stressors.2 Despite these advantages, the incorporation
of ascorbic acid in cosmetic formulations poses several challenges, particularly regarding its stability. Ascorbic acid is unstable to light, heat, leading to decomposition over time. One of the most common stability issues is colour change, especially in aqueous solutions, causing noticeable discolouration and reduced efficacy, which can result in customer complaints and product quality concerns.
HO HO H
4 O 1 O 3
6 5
2 HO OH
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- +
H H
+ +
Additionally, the strong ionic character of
ascorbic acid can disrupt emulsification systems, leading to viscosity loss and formulation instability. This instability arises from its molecular structure, particularly the hydroxyl group at position 3, which has the lowest acid dissociation constant (pKa) of 4.2. At the pH levels commonly used in cosmetic formulations, ascorbic acid exists in a dissociated ionic form (Figure 1), which can interfere with formulation integrity.
The novel ascorbic acid derivative VC-3G To address these issues, we developed VC-3G, a patented ascorbic acid derivative that sets a new
HO HO H
O Figure 1: Non-dissociated structure and dissociated structure of ascorbic acid
standard in stability and efficacy. VC-3G is a state-of-the-art ascorbic acid
derivative characterized by its high stability, manufactured with our proprietary technology. It has been proven to resist degradation over time, maintaining low colouration. Furthermore, when formulated into gels and creams, VC-3G does not induce common stability issues like viscosity reduction or separation, ensuring optimal performance. The ascorbic acid derivatives commonly used
in the cosmetics market also feature a substituent at the 2-position hydroxyl group, but like ascorbic acid, they have strong ionic properties. VC-3G has a molecular structure in which a
HO HO
O O OH
HO HO
H O
O
O OH Figure 2: Molecular structure of VC-3G September 2026 PERSONAL CARE MAGAZINE
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