ABSTRACT
1. Introduction Cutaneous aging is a multifactorial process affecting different constituents of the skin (Reddy and Gilchrest 2011). During aging, distribution of subcutaneous fat is altered. The subcutaneous fat is significantly lost from the dorsum of the hand, face and shin, but accumulates in the waist or thigh (Kligman et al. 1985; Farage et al. 2007). In the epidermis, signs of aging include lowering of the levels of collagen IV and collagen VII at the basement membrane, flattening of the rete ridge, thinning of the epidermis, and lowering of the levels of ceramides, free fatty acids, squalene and epidermal cholesterol (El-Domyati et al. 2002; Hayashi et al. 2003; Sandby-Moller et al. 2003; Neerken et al. 2004; Fore 2006). In the dermis, aging leads to fragmentation of elastin, an increase in collagen degradation, and a decrease in production of dermal collagen, proteoglycans and glycosaminoglycans (Giacomoni et al. 2000; El-Domyati et al. 2002; Carrino et al. 2003; Fore 2006; Varani et al. 2006; Farage et al. 2007). Owing to atrophy of the supporting dermis, the skin hydration level and skin repair capacity are reduced (Farage et al. 2009). Elderly people, therefore, are predisposed to susceptibility to skin injuries and disorders (including altered wound healing, immunologic changes, dermatologic diseases, and skin cancers). Along with the increasing understanding of the mechanism of cutaneous aging, opportunities have been brought to research into anti-aging treatment. In an earlier study, oral administration of isotretinoin was found not only to improve skin thickness, skin colour, skin elasticity and skin tone, but also to reduce pigmented lesions, mottled hyperpigmentation and wrinkles (Hernandez-Perez et al. 2000). More recently, caloric restriction has been reported to prevent or delay age-associated histomorphological changes by reducing the age-related increase in the depth of the epidermis, dermis, and fat layer, and by increasing the collagen percentage, elastic fiber fraction area and dermal fibroblast population (Bhattacharyya et al. 2005). These are only few examples of the large number of works devoted to skin rejuvenation over the past 20 years. More examples of approaches explored for treatment of aging skin are listed in table 1. These approaches can be categorized into cosmetic procedures and cosmeceutical interventions. Many of them have been evaluated clinically for skin treatment (Beer 2011; Blyumin-Karasik et al. 2011; Yokoyama et al. 2014). Apart from the advances reported in the scientific literature, innovations reported in the patent literature are also worth noticing. As these innovations may not have been documented in scientific journals due to the issue of intellectual property, patent publications are a rich knowledge source complementary to the conventional scientific literature. 2. Cosmeceuticals in the patent literature As far as the patent literature on cutaneous aging is concerned, the number of patents on cosmeceuticals much exceeds that on cosmetic procedures. This may be because cosmeceuticals in general are more convenient for self-application and are less invasive (McCullough and Kelly 2006). This gives cosmeceuticals a higher practical potential. In 2011, a patent was published on a composition comprising a dill extract, a blackberry leaf extract, and a cosmetically acceptable carrier (Kizoulis et al. 2011). In vitro studies showed that the blackberry extract stimulates tropoelastin production (Kizoulis et al. 2011). Compared to a composition containing either a dill extract or a blackberry leaf extract, the one containing