Green perilla leaf extract ameliorates long-term oxidative stress induced by a high-fat diet in aging mice

Oxidative stress is caused by an imbalance between harmful free radicals and antioxidants. Long-term oxidative stress can lead to an "exhausted" status of antioxidant defense system triggering development of metabolic syndrome and chronic inflammation. Green perilla (Perilla frutescens) is commonly used in Asian cuisines and traditional medicine in southeast Asia. Green perilla possesses numerous beneficial effects including anti-inflammatory and antioxidant functions. To investigate the potentials of green perilla leaf extract (PE) on oxidative stress, we induced oxidative stress by high-fat diet (HFD) in aging mice.

C57BL/6J male mice were fed HFD continuously for 53 weeks. Then, mice were divided into three groups for 12 weeks: a normal diet fed reference group (NDcon), high-fat diet fed group (HDcon), and high-fat diet PE treated group (HDPE, 400 mg/kg of body weight). Biochemical analyses of serum and liver tissues were performed to assess metabolic and inflammatory damage and oxidative status. Hepatic gene expression of oxidative stress and inflammation related enzymes were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR).

PE improved hepatopathology. PE also improved the lipid profiles and antioxidant enzymes, including hepatic glutathione peroxidase (GPx) and superoxide dismutase (SOD) and catalase (CAT) in serum and liver. Hepatic gene expressions of antioxidant and anti-inflammatory related enzymes, such as SOD-1, CAT, interleukin 4 (IL-4) and nuclear factor erythroid 2-related factor (Nrf2) were significantly enhanced by PE. PE also reduced the levels of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) in the serum and liver; moreover, PE suppressed hepatic gene expression involved in pro-inflammatory response; Cyclooxygenase-2 (COX-2), nitric oxide synthase (NOS), interleukin 1 beta (IL-1β), and interleukin 6 (IL-6).

This research opens opportunities for further investigations of PE as a functional food and possible anti-aging agent due to its attenuative effects against oxidative stress, resulting from HFD and aging in the future.