Figure 4 – Effect of 2 % AHE extraction on gene expression of AGE ( a ) & AGE-R1 ( b ) receptors & RAGE in IL-1β-stimulated NHDF cells
‣ Our data showed that AHEtreatment has a significantly reductive effect on the formation of ROS compared to Trolox , an antioxidant and a structural analogue of vitamin E , as a positive control ( Figure 3 ). A significant decrease in RCAN1 expression was also observed : with 1 % AHE , it was 57 % of the control levels ; with 2 % AHE , 31 %; and with 2 % AHE plus IL-1β , only 14 %.
Counteracting AGEs
AGEs originate from non-enzymatic reactions of proteins with reducing sugars . They also seem to accumulate in extrinsically aged skin . 8 Previous studies reported that AGEs could accumulated in dermal elastin and collagens and interact nonspecifically with the cell membrane of dermal fibroblasts . 9 Therefore , AGEs may play a role in skin ageing , since binding them with their multi-ligand receptors , RAGEs , is known to induce oxidative stress and inflammatory responses . However , other AGE-specific cell surface receptors , such as AGE-R1 , -R2 and -R3 , counteract the function of RAGE . These receptors are involved in AGE-homeostasis , thus reducing AGE levels and thereby suppressing oxidative stress and inflammation . 10 We therefore investigated the effect of AHE on the gene expression patterns of the different classes of AGE receptors . We observed a
Induction of woundhealing factors
In wound re-epithelialisation , E-cadherin coordinates tractional forces promoting collective and directional migration of epithelial cells . 11 It is expressed in two isoforms of different molecular weight : B1 ( 120kDa ) and B2 ( 90-100kDa ). By participating in multiple signalling cascades and the formation of focal adhesions , meanwhile , paxillin plays a critical role during cellular migration and thus , wound healing . 1 % AHE induced increases of 57 % and 25 % E-cadherin B1 and B2 expression respectively on the injured skin model compared to the control . Treatment with 5 % AHE resulted into 0.8-fold repression of E-cadherin B1 and complete repression of B2 on the injured skin model but 1.5-fold induction of B1 and 1.7-fold induction of B2 on the intact skin model . Paxillin , on the other hand , was induced 2.4-fold when cells were treated with 5 % AHE . These results suggest that 1 % and 5 % AHE have a positive effect on wound healing by promoting E-cadherin and paxillin expression in human keratinocytes . A reduction in the levels of functional dermal components , such as collagens , results in the emergence of clinical ageing features , such as wrinkles and reduced elasticity . 12 After 28 days of treatment with a 2.5 % AHE-containing day cream , significant improvements were observed in terms of : skin firmness ( tensing effect ) by 4 %; viscoelasticity ( anti-ageing action ) by 11 %, and plasticity by 12 % in 43 %, 67 % and 48 % of subjects , respectively . There was also a significant increase in the cutaneous hydration rate by 6 % and radiance under the eyes by 17 %, consistent with the moisturising and radiant skin effect of the product , respectively .
34 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981