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Expert Session
Into the Bottle: Firming Plant Peptide Serum
September 14, 2025
Photos by: Bliss Kaufman
What inspired this formula?
Like a lot of our formulas, Firming Plant Peptide Serum was a personal request from Jenni. With Daily Vitamin C Serum and Nightly Retinol Serum anchoring Oak’s serum assortment, Jenni wanted something more targeted and advanced—specifically a peptide-based treatment to support firmness and elasticity. The ask was to harness plant-based ingredient technology for visible results, while staying true to Oak's signature gentle approach.
What exactly are peptides?
Peptides are tiny fragments of protein—also known as short chains of amino acids—that the body uses as building blocks for larger proteins like collagen, elastin, and keratin. They also act as natural signals in the body. For example, insulin is a peptide that helps regulate blood sugar, endorphins are peptides that help modulate pain and mood, and oxytocin is a peptide that helps supports social bonding and relaxation. In skincare, specific peptides act like messengers that cue the skin to behave in targeted, beneficial ways. In the epidermis, peptides help support the skin barrier, boost hydration, and calm visible irritation. Through deeper signaling pathways in the dermis, peptides can encourage processes associated with collagen and elastin—translating to a firmer, smoother, and more resilient-looking skin over time. In short, peptides offer a non-invasive way to support healthy-looking tone and texture.
Why did we choose plant-derived peptides, and what sets them apart from other types of peptides?
We built this formula around plant-derived ingredients to keep it gentle, effective, and aligned with our sustainability standards. In cosmetics, formulators can draw from several peptide sources including plants (extracted from soy, rice, peas, etc.), animal byproducts (derived from milk, collagen, silk, etc.), synthetic peptides (lab-created to mimic natural sequences), or biotechnologically derived peptides (produced via fermentation with yeast, bacteria, or algae). For Firming Plant Peptide Serum, our chosen peptide is Hydrolyzed Pisum Sativum Peptide, or Pea Peptide. It’s “hydrolyzed,” meaning the protein is broken into smaller peptide fragments and amino acids. Smaller peptide fragments have better skin affinity—making them more available to the skin’s surface, where they can support hydration, a stronger skin barrier, and a visibly plumper, firmer look over time.
What does Tiger Plant contribute to the formula?
Tiger Plant actually gets its name from ancient folklore that injured tigers would roll in it to heal their wounds. In our formula, this ingredient is paired with exosomic plant stem cell technology—where nano-sized vesicles, or naturally occuring carriers, act like cellular messengers and help carry peptide-rich molecules to the skin's surface to support renewal. Often referred to as the “plant of longevity,” this stem-cell-signaling peptide is effective at helping reverse visible signs of aging. Our blend is exceptionally peptide-dense, with 16,000+ peptides in this ingredient alone.
What about Celtic Sea Extract? How does that ingredient benefit the skin?
Derived from a marine plankton native to the coast of Brittany, France—and obtained via blue-biotechnology fermentation—this extract is highly water-binding and forms a micro-thin, breathable film on the skin. It helps lock in moisture, protect against environmental stressors, and leave behind a plumper-looking complexion.
Tell us about the texture and the feel of the formula.
This formula is fragrance-free, meaning you may notice the subtle, natural aroma of the raw ingredients. Not adding scent was an intentional choice, so we could prioritize stability and the formula’s firming benefits. Texture-wise, it’s our thinnest serum—a lightweight gel that melts in quickly and layers beautifully with other skincare steps. And while the formula works on top of the dermis layer of skin, it also absorbs deeper for below-the-surface benefits.
Who is this serum best suited for? Would you say it’s more preventative, corrective—or both?
It’s suitable for most skin types—including sensitive—and leans preventative while also offering corrective benefits. By supporting skin resilience, hydration, and antioxidant defense, it helps delay and soften the look of early signs of aging. If you’re just starting to notice changes, this is an ideal choice.
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