Biotransformation of Xenobiotics

Abstract

Xenobiotics, which are absorbed into biological systems by passive diffusion across membranes are usually lipid soluble and not ideally suited for excretion. Indeed very lipophilic substances may remain in the mammalian body for many years. After a xenobiotic has been absorbed, it may undergo biotransformation to products which are rapidly excreted and therefore elimination of the compound from the animal is facilitated. However, biotransformation may also change the biological activity of the substance. Hence, the metabolic fate of the compound can have an important bearing on its toxic potential, the disposition of the compound in the body and the excretion of the compound. The metabolic reactions involved are usually divided into phase 1 and phase 2 reactions, the latter being conjugation reactions. The products of metabolism are usually more water soluble than the original compound. Although usually detoxifying, these reactions, especially phase 1 ones, sometimes increase toxicity.

Protective Effects of the Flavonoid Chrysin against Methylmercury-Induced Genotoxicity and Alterations of Antioxidant Status,In Vivo

“…This difference between the observations in mammal cells culture, such as HepG2, and the present data may be explained, at least partly, to the metabolism system of them. HepG2 cells possess mainly high expression of enzymes of phase I of metabolism [ 46 ]; the same occurs in systems that used the S9 fraction (which also have high levels of phase I enzymes) [ 47 ], while in animals, the metabolism comprises a balanced expression of phase I and phase II enzymes [ 48 ].…”

Bioaccessibility and bioavailability of phenolic compounds

“…epicatechin) out of the intestinal cells, but the flux direction is from cytoplasm to lumen attributed to its expression on apical membrane of small and large intestine (Estudante et al, 2013). As a result, except for cationic anthocyanins, the actual absorbability of various orally ingested phenolics may be suppressed by efflux mechanism Adapted from Timbrell and Marrs (2009), Smart and Hodgson (2018), Shimada et al (2006), and Hodgson et al (2001).…”

Activity of the Ethanolic Extract from Fruit of Empetrum nigrum var. japonicum on CCl4Induced Liver Injury in BALB/c Mice

“…전리 방사선이나 약물 또는 생체 이물질(xenobiotics)에 대한 노출 등 많은 요인에 의해 자 유 라디칼의 생성 및 산화적 스트레스가 증가한다 (Ko and Lim, 2006). 본 실험에서 사용한 CCl 4 투여 동물모델은 여 러 자생식물의 간보호 및 항산화 효능을 평가하기 위하여 많이 이용되고 있다 (Choi and Kim, 2000;Lim, 2010 (Recknagel, 1983;Timbrell, 1993 (Lee et al, 2003). 독성 물질 등 여러 가지 인자에 의해 생성된 산소 라디칼과 반응한 불포화 지방산은 여러 반응을 거쳐 최종적으로 MDA를 형성한다 (Vengerovskii et al, 1990…”