Anti-aging effects of plant extracts on skin and brain in hairless mice

Abstract

Aging is a natural process with the passage of time. As aging progresses, the body changes externally and internally, with a decline in organ function. These changes occur primarily in the skin and brain. Reduced water retention and increased wrinkle formation are the most common phenotypes of aged skin. In case of the brain, cognitive deficits and memory impairment occur in a large number of the elderly populations. Lots of aged populations desire to be rejuvenated for maintaining a healthy body. In this study, I tried to find out anti-aging agents especially those that affect skin and brain functions by using 133 ethanolic extracts of dietary plants. Extracts of two plant species were selected for being protective against skin and brain aging, respectively. Perilla frutescens (L.) Britt. (Lamiaceae) is an herb used as a food and a traditional medicine in Korea. In this study, P. frutescens leaf extract (PLE) significantly inhibited basal and UV-induced matrix metalloproteinase-1 (MMP-1) expression in a dose-dependent manner, and promoted type I procollagen production irrespective of UV irradiation. The inhibitory effect of PLE on MMP-1 expression was mediated by inhibition of ROS/mitogen-activated protein kinase (MAPK)/AP-1 signaling pathway. Furthermore, PLE significantly reduced epidermal skin thickness and MMP-13 expression induced by UV in a UV-irradiated animal model. Tomato (Lycopersicon esculentum) is consumed worldwide as fruit, and is also known as a super food because of their many physiological activities. In this study, oral administration of tomato ethanolic extracts (TEE) for 6 weeks significantly increased the exploration time of novel objects, proliferation of hippocampal cells, and synaptic plasticity in 12-month-old mice compared to those in vehicle-treated aged mice. The memory enhancing effect of the TEE treatment resulted from an increased expression of brain-derived neurotrophic factor (BDNF) and the subsequent activation of ERK/CREB signaling pathway in the hippocampus. In conclusion, the selected antiaging agents, PLE and TEE, showed an anti-aging effect on the skin by inhibition of the ROS/MAPK/AP-1 pathway and on the brain by the BDNF/ERK/CREB pathway. These results suggest that PLE and TEE can be potential agents for prevention of skin aging and treatment of age-related memory impairment and neurodegenerative disorders.