Phase I and Phase II Enzyme Induction in Human Keratinocytes Treated with a Standardized Grapefruit Extract Rich in Bioflavonoids
Authors
Lueder M, Caldelari R, Girling P, Blank J
Institution
QENAX AG, Zug
Country
Switzerland
Year
2010
Journal
IFSCC
Abstract
Humans are constantly exposed to harmful foreign chemicals and materials from exogenous and endogenous sources. As a result, defense mechanisms have evolved to protect against toxin overload cells are under constant threat from metabolic waste products and xenobiotics. The formation of phase I and phase II metabolism mobilizes and excretes these mainly lipophilic toxins. This clears the cell of molecular rubbish, thereby preventing molecular damage, and aging. According to the literature, citrus fruits rich in bioflavonoids such as naringin and hesperidin can help to protect the body against toxin overload when taken orally. The use of such natural actives is continuously increasing as the understanding of their ability to slow the aging process improves. One of the most powerful detoxification mechanisms is centered on the phase I and phase II enzymes. Phase I activation of lipophilic compounds is carried out by enzymes of the CYP450 family [5]. This phase I biotransformation creates an activated intermediate that is either directly eliminated from the body, or more commonly becomes a substrate for one of the phase II conjugation enzymes prior to elimination from the cell. Phase II enzymes such as quinone reductase perform a broad variety of detoxification reactions. Quinone reductase is able to detoxify a broad range of quinones produced by oxidative metabolism and is known to be expressed in human keratinocytes. Here we summarize two in vitro studies which show that a standardized grapefruit extract rich in naringin and hesperidin significantly induces the activity of both phase I and phase II enzymes in human primary epidermal keratinocytes.
Product use
Induction of cytochrome P450 (CYP1A1) (measured by fluorescence quantification) and Quinone reductase activity (by NADPH-quinone reductase assay)