A newish peptide with the promise of mimicking the effects of the skincare superstar, retinol (vitamin A) but without its negative side effects. Similar to retinol, Myristoyl Nonapeptide-3 is claimed to increase cell turnover and to promote the synthesis of collagen but without skin irritation or stinging.
To back up its claim, the German manufacturer did a so-called gene array screening test, where they examined the effect of the molecule on 96 skin-related genes. They did screening for both retinoic acid (the active form of retinol) and our guy Myristoyl Nonapeptide-3. They found that retinoic acid upregulates 21 of the 92 studied genes, and amongst those, 16 genes are also upregulated by Myristoyl Nonapeptide-3. So they trade named the molecule as Retinopeptide 189, as in a peptide that mimics the effects of retinoic acid.
To further prove their point, Symrise (the manufacturer) went ahead and did some ex-vivo testing (meaning testing on human skin explants). They compared a 0.1% retinoic acid solution with 5% and 10% Retinopeptide 189 cream and found that the 10% cream induces a significant increase (43%) in collagen-1 that is comparable to the effect of 0.1% retinoic acid (which performed even better with more than a 50% increase).
They also found that both retinoic acid 0.1% and Retinopeptide 189 5% cream increased epidermal cellular layers in the skin explants showing that both ingredients can increase cell turnover, however retinoic acid did significantly better both in active effects as well as side effects.
Unfortunately, there are currently no in-vivo test results (at least with could not find any), so if you prefer the tried and true, stick with retinol. However, if you are the adventurous type or if your skin is sensitive and cannot tolerate retinoids, Myristoyl Nonapeptide-3 is a promising alternative.