Daily sunscreen use is the best protection we have against premature aging and skin cancer, but dermatologists also know that sunscreen isn’t a perfect shield. Even broad-spectrum formulas let small amounts of ultraviolet light through, particularly UVA rays, which penetrate more deeply into the skin. Over the years, that residual exposure can still cause changes in your skin DNA and trigger collagen loss, resulting in visible signs of damage like discoloration and skin laxity.

Recognizing this challenge, scientists at the University of Minnesota’s Center for Drug Design developed ProteXidine™, a molecule designed to help the skin respond to damage that sunscreen alone can’t entirely prevent. Through a partnership, that same research innovation now powers AST Brightening & Firming Complex, bringing advanced laboratory science into a formula designed for everyday skincare.

The Problem: Sun Damage and Skin Aging

Dermatologists agree that UV exposure is the leading cause of premature skin aging. When ultraviolet light reaches the skin, it creates several kinds of damage at once:

  • DNA Mutations: When UV light strikes DNA, it can fuse bases together in ways the body doesn’t expect. These small mutations disrupt the cell’s normal “instructions” for repairing itself. Over time, the errors add up, making it harder for skin cells to heal and regenerate properly.
  • Collagen Breakdown: Collagen is the protein that keeps skin structured and springy. UV exposure activates enzymes that chop collagen into fragments faster than the body can replace it. As the scaffolding thins, skin gradually loses its firmness and begins to sag or wrinkle.
  • Pigment Changes: Melanin is produced to protect the skin from sun damage, but UV light and oxidative stress can throw off its balance. Instead of an even glow, pigment clusters in certain spots, leading to freckles, sun spots, or blotchy areas we recognize as hyperpigmentation.
  • Oxidative Stress: Sunlight and pollution can generate unstable molecules called reactive oxygen species (ROS). In small amounts, your skin’s natural enzymes can keep them under control, but when ROS levels get too high, they damage lipids, proteins, and DNA all at once.

Of particular interest to the University of Minnesota’s Center for Drug Design was how ROS interfere with how cells normally behave. In pigment-producing cells, they overstimulate tyrosinase, the enzyme that drives melanin synthesis. This disruption throws the entire pigment system off balance so that, instead of an even, protective tan, you end up with concentrated patches of color in the form of freckles, blotches, and a generally patchy complexion.

In addition to discoloration, ROS also undermine the skin’s repair architecture. They cause collagen fibers to weaken faster than the body can replace them, and elastin to lose its usual organized structure, making it harder for skin to bounce back from damage. Because ROS interfere with pigment pathways and structural proteins at the same time, dark spots often appear alongside fine lines or uneven texture as visible signs of multiple repair systems under strain.

Over time, our skin becomes less efficient at self-correcting these issues. Pigment sits longer in our skin as cellular turnover slows, meaning that what could have once been a temporary issue with melanin production begins to leave permanent marks.

Scientific Breakthrough: ProteXidine™

What researchers at University of Minnesota’s Center for Drug Design have done is reinforce the skin’s own ability to recognize and repair early injury with the development of ProteXidine™, a molecule representing more than a decade of research focused on disrupting the root causes of photoaging.

Unlike antioxidants that neutralize ROS after they’re already formed, ProteXidine™ works as a molecular decoy. When ultraviolet light strikes DNA, it often causes two thymine bases to fuse. These fusions, called dimers, are the most common form of UV-induced DNA damage and a key driver of premature aging. ProteXidine™ is designed to mimic that vulnerable DNA segment, so it acts as a kind of decoy, diverting ROS away from critical cellular structures.

Steve Hernandez, Senior VP of Research & Development at Topix Pharmaceuticals— the industry partner that licensed ProteXidine™ from the University of Minnesota—explains:

“Sunscreens are very good at shutting down erythema (reddening of the skin). In other words, when you put sunscreen on, and you’re not going to get a sunburn for much longer than it would take without it. Therefore, you feel that you can safely extend your time in the sun. But, while you’re not burning, you are still damaging your skin and generating these markers of high concern in your DNA molecules. These are called Cyclobutane Pyrimidine Dimers [CPDs] also known as thymine dimers in the DNA molecule.”¹

In laboratory studies, skin pre-treated with ProteXidine™ developed fewer CPDs. Researchers also found that ProteXidine™ encouraged skin to clear out damaged cells more efficiently, speeding turnover in pigment-prone areas. Early findings suggest this dual action — reducing new DNA lesions and improving recovery of existing damage — helps preserve collagen density and maintain skin’s structural integrity under UV stress.

Watch the April 10, 2025 Mini Symposium Celebrating ProteXidine’s Journey from Lab to Market

From the Lab to Your Vanity

Scientific advances only matter when they leave the lab and make a difference in people’s lives. That’s why the ongoing collaboration between Skintherapy® and the University of Minnesota’s Center for Drug Design is so important. By working together, university researchers and product developers have taken the discovery of ProteXidine™ band translated it into a treatment patients can now use every day: AST’s Brightening & Firming Complex. The complete formula is built to tackle multiple signs of photoaging at once:

  • ProteXidine™ addresses the earliest step by protecting DNA from UV-induced changes that set pigment pathways into overdrive.
  • Hexylresorcinol not only fades visible discoloration but also helps calm irritation, lowering the risk of pigment rebound after inflammation or procedures.
  • Arbutin, a plant-derived brightener, gently slows excess melanin production where pigment has already surfaced, doing so without compromising the skin barrier.
  • Hexanoyl dipeptide-3 signals the skin to renew itself in a controlled way, encouraging pigment-heavy cells to shed naturally. This gradual, biologically aligned exfoliation prevents the buildup that leads to dullness while avoiding the cycle of irritation and rebound darkening common with harsher acids.

Together, these components create a formula that not only reinforces the skin’s natural resilience against future UV-related change but also gives you a brighter, more radiant complexion. For patients, it’s the rare product that connects university-level science with visible, everyday results.

How to Use AST Brightening & Firming Complex in a Skincare Routine

Adding the AST Brightening & Firming Complex to your daily regimen is simple, but timing and layering are crucial for achieving the best results.

  1. Use once or twice daily. In the morning, apply after cleansing and before sunscreen. At night, apply after cleansing and toning, and before any heavier moisturizers or overnight treatments.
  2. Apply a pea-sized amount and smooth it gently into skin until absorbed.
  3. AST Brightening & Firming Complex is not a substitute for SPF. Always apply SPF 30 or higher after applying your moisturizer. As Hernandez explains, “Your first line of defense from the sun is SPF. You can think of antioxidants as a kind of second line of defense, but they aren’t going to trap all of those free radicals. Our clinical data suggests that ProteXidine™ allows your body to make more repair enzymes faster, thereby providing another line of defense against the sun.”

ADCI & AST at the Cutting Edge of Skin Science

At Advanced Dermatology & Cosmetic Institute, Dr. Elizabeth Briden has spent decades bridging research and patient care. With her experience as a board-certified dermatologist and clinical professor at the University of Minnesota, she has built her practice around skin rejuvenation, cancer prevention, and evidence-based cosmetic dermatology.

Partnering with the University of Minnesota’s Center for Drug Design was a natural extension of that mission. ProteXidine™ represents a new way of thinking about sun protection and AST Brightening & Firming Complex places that innovation into your hands.

AST Brightening & Firming Complex  with ProteXidine™ is available exclusively through Advanced Skin Therapeutics. You can shop online or visit us in person to learn more about how this formula supports age-defying skin and stops hyperpigmentation before it can start.

  1. Published: Jul 5, 2024  by Rowan Lynam NEW BEAUTY