Three-level green biotech protection of skin collagen

1 UV radiation, both UVB and UVA, induces an increase in the level of reactive oxygen species (ROS), including H2O2, in tissues and cells. In turn, these species activate micro-inflammatory processes, mediated by nuclear transcription factors, in the skin. UVB (from 280 nm to 320 nm) is absorbed by the epidermis and, to a particularly high degree, by keratinocyte DNA, leading to the formation of thymidine dimers2 with significant mutagenic and photoageing effects.3 UVA (from 320 nm to 400 nm), on the other hand, is able to penetrate the deeper layers of the skin, such as the dermis, where its energy is absorbed in the form of activated electrons. These electrons are then donated to dissolved molecular oxygen by various chromophoric molecules, thereby generating superoxide anions or other ROS.4 Another major skin ageing factor is cigarette smoke, which provokes cutaneous damage and reduces capillary flow in the dermis, thereby generating a reduction in dermal supply of oxygen and nutrients. Furthermore, reduced levels of collagen and elastin, with consequent loss of elasticity and tone, alterations in the vascular bed and formation of teleangectasiae, have been found in the skin of chronic smokers with respect to non-smokers.5 These effects of cigarette smoke are all consequences of a condition of oxidative stress determined by the formation of ROS, which reduce the biosynthesis of collagen by dermal fibroblasts. In fact, chemicals present in extracts of tobacco itself have been reported to directly induce the release of matrix metalloproteinases (MMPs), which degrade, with varying degrees of selectivity and specificity, the proteins of the extracellular matrix.5 The release of MMPs by cigarette smoke occurs via various mechanisms, including the activation of the transcription factor aryl hydrocarbon receptor (AhR), similar to the glucocorticoid receptor, present in the cytoplasm and in the cell nuclei. AhRs are also activated by substances formed in the skin following exposure to UV rays, leading to an acceleration in the cutaneous ageing processes, already precipitated by risk factors such as cigarette smoke, other oxidative agents or environmental pollutants.6,7 Finally, several common cosmetic ingredients such as zinc oxide8 and titanium dioxide nanoparticles, via an increase in oxidative stress and ROS formation, have also recently emerged as factors with potential effects on cutaneous senescence.9 Thus, ROS represent a point of convergence of various mechanisms implicated in skin ageing. Regarding their mechanism of action, ROS are able to activate the nuclear transcription factor AP1, a heterodimer constituted by the proteins c-fos and c-Jun,10 which induces a reduction of the synthesis of collagen in fibroblasts and an increase of the secretion of various MMPs, enzymes capable of degrading all of the main constituents of the extracellular matrix, in fibroblasts and keratinocytes.11 In particular, MMP1 is a collagenase responsible for fragmenting type I of mature fibrillar collagen, the most prevalent form of collagen in the dermis, which in turn provokes micro-lesions in the matrix. In young skin, new collagen, synthesised by dermal fibroblasts, is able to repair MMP1-mediated damage, while older skin, or that particularly exposed to UV or cigarette smoke, for example, manifests a reduction of pro-collagen synthesis, due to both the inhibitory action of AP1 on collagen genes and the inhibitory action exerted by the fragments of type I collagen derived from the activity of MMP1 on fibroblasts.12 The end result of these processes is an imbalance in the normal collagen synthesis/degradation turnover, with the reduction in the fibrillar collagen content of the dermis leading to a loss of mechanical tension, i.e., tone and consistency, in the skin, which manifests itself as wrinkles and micro-wrinkles.13 Repeated exposure to oxidative agents, such as UV, cigarette smoke or other factors, keep the process of matrix degradation active, leading to a progressive accumulation of damage which, particularly in older skin, is not completely recovered due to the reduction in efficiency of the endogenous systems which synthesise components of the extracellular matrix1,14 (Fig. 1). Thus, products which prevent and limit the damage to the constituents of the extracellular matrix of the skin, produced by physiological ageing and exacerbated by a host of environmental stress factors and other agents, are extremely desirable research goals.

Aim of the study

 An ingredient was obtained, via a green biotech process, from a stable and selected cell line of Gardenia jasminoides (Rubiaceae) (Fig. 2). The composition of the culture medium and the fermentation conditions, namely temperature and oxygenation, were optimised specifically for the Gardenia jasminoides cell line, and were scrupulously controlled throughout the production process in order to guarantee standardisation of the plant biomass.15 Feruloil-6-glucoside was identified and used as a marker of the quality and reproducibility of the different batches of the cell cultures. Gardenia jasminoides is a plant traditionally utilised for ornamental purposes and for extraction of fragrances for cosmetic use, explaining why there is scarce information in the literature regarding its composition and potential nutritional and cosmetic applications. In this context, a green biotech process which permits the development of new ingredients with as yet unexplored chemical, biological and cosmetic properties, like the preparation based on meristem (or plant stem) cells of Gardenia jasminoides described in this article, is extremely useful.