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SynopsisSkin ageing is an irreversible process that is caused by both intrinsic and extrinsic factors. The possibility of arresting or delaying skin ageing represents a large research area and has a big potential in the cosmetics sector. Recently, the polypeptide lysine-threoninethreonine-lysine-serine (KTTKS) has attracted a lot of attention and it features in numerous up-market cosmetic products where it has become erroneously associated with the term 'pentapeptide'. In this study, we review in detail KTTKS and its major derivatives, in terms of the limited information in the literature and an appraisal of its physicochemical and theoretical skin permeation properties. There appears to be a sound in vitro basis for its action on fibroblasts due to its stimulatory effect on extracellular matrix synthesis, where the stimulatory effect of KTTKS is specific to collagen types I and III and fibronectin expression. However, there is a surprising absence of in vitro skin penetration data in the literature, and there are relatively few clinical studies using these materials. Ré suméLe vieillissement cutané est un processus irréversible causé par des facteurs tant intrinsèques qu'extrinsèques. La possibilité d'arrêter ou de retarder le vieillissement cutané représente un grand secteur de recherche et grand potentiel dans le secteur cosmétique. Récem-ment, le polypeptide lysine-thréonine-thréonine-lysine-serine (KTTKS) a attiré l'attention. Il est présent dans de nombreux produits cosmétiques haut de gamme où il est faussement associé au terme de 'penta peptide'. Dans cette revue, nous examinons en détail KTTKS et ses dérivés majeurs, avec dans la littérature des informations limitées quant à l'évaluation de ses propriétés physicochimiques et celles de perméation cutanée théoriques. Il semble y avoir un fondement à propos de son action in vitro sur des fibroblastes avec un effet de KTTS stimulant de la synthèse de la matrice extracellulaire, avec une activité spécifique aux collagènes de type I et III et à l'expression de la fibronectine. Cependant, il y a, dans la littérature, une absence surprenante de données concernant la pénétration cutanée in vitro et il y a relativement peu d'études cliniques utilisant cet ingrédient.

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Coadministered pomegranate rind extract (PRE) and zinc (II) produces a potent virucidal activity against Herpes simplex virus (HSV); however, HSV infections are also associated with localised inflammation and pain. Here, the objective was to determine the anti-inflammatory activity and relative depth penetration of PRE, total pomegranate tannins (TPT) and zinc (II) in skin, ex vivo. PRE, TPT and ZnSO were dosed onto freshly excised ex vivo porcine skin mounted in Franz diffusion cells and analysed for COX-2, as a marker for modulation of the arachidonic acid inflammation pathway, by Western blotting and immunohistochemistry. Tape stripping was carried out to construct relative depth profiles. Topical application of PRE to ex vivo skin downregulated expression of COX-2, which was significant after just 6h, and maintained for up to 24h. This was achieved with intact stratum corneum, proving that punicalagin penetrated skin, further supported by the depth profiling data. When PRE and ZnSO were applied together, statistically equal downregulation of COX-2 was observed when compared to the application of PRE alone; no effect followed the application of ZnSO alone. TPT downregulated COX-2 less than PRE, indicating that tannins alone may not be entirely responsible for the anti-inflammatory activity of PRE. Punicalagin was found throughout the skin, in particular the lower regions, indicating appendageal delivery as a significant route to the viable epidermis. Topical application of TPT and PRE had significant anti-inflammatory effects in ex vivo skin, confirming that PRE penetrates the skin and modulates COX-2 regulation in the viable epidermis. Pomegranates have potential as a novel approach in ameliorating the inflammation and pain associated with a range of skin conditions, including cold sores and herpetic stromal keratitis.

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