Interaction of the di-catechols rooperol and nordihydroguaiaretic acid with oxidative systems in the human blood

Biotransformation of 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanone (Nnk) in Peripheral Human Lung Microsomes

“…PHS contributions were assessed using INDO (Smith and DeWitt, 1995). Effects of NDGA, a LOX inhibitor (Van der Merwe et al, 1993), were also assessed. For immunoinhibition studies, 1.0 mg of microsomal protein and 200 g of either anti-CYP2A6, CYP3A4/5, CYP2E1, or CYP2B6 supplied in 25 mM Tris buffer (pH 7.5) were incubated on ice for 20 min before use in incubations, as recommended by the supplier.…”

Hypoxis hemerocallidea—Not merely a cure for benign prostate hyperplasia

“…5). Studies by Van der Merwe et al (1993) on the effect of rooperol and NDGA on oxidative systems in the human blood gave comparable results in the inhibition of leucotrine synthesis in the polymorpho-nuclear leukocyte and prostaglandin synthesis in platelet microsomes. Both NDGA and rooperol were also found to interact with the oxidative processes in the blood.…”

‘African potato’ (Hypoxis hemerocallidea corm): a plant‐medicine for modern and 21st century diseases of mankind? – a review

“…It is still unclear at the moment, whether the ability of rooperol to inhibit inflammatory processes in vitro and in vivo, is as a consequence of its direct ability to inhibit the production of pro-inflammatory cytokines, tumour necrosis factor (TNF)-α, and interleukins; or due to its inhibitory effects on enzymes involved in the synthesis of pro-inflammatory mediators, such as leukotrienes and prostaglandins. In an earlier study, Van der Merwe et al (1993) showed that rooperol is a potent inhibitor of lipo-oxygenase (an enzyme that catalyses the first-step in the conversion of arachidonic acid to leukotrienes), but not cyclooxygenase (COX), which catalyses the rate-limiting step in the conversion of arachidonic acid to prostaglandins (Fig. 1).…”

“…However, direct inhibitions of COX-1 (constitutive) and COX-2 (inducible) isoforms of the COX enzymes by extracts of H. hemerocallidea corm, have also recently been reported (Gaidamashivili and Van Staden, 2006;Steenkamp et al, 2006). Despite the prevailing uncertainties about the precise mechanism/s by which rooperol exerts its antiinflammatory effects, it is important to recognize that rooperol shares intimate structural similarity with a well-known, strong antioxidant, nordihydroguairectic acid (Nair et al, 2007b), and comparably inhibits leukotriene and prostaglandins synthesis in polymorphonuclear leukocyte and platelet microsomes, respectively (Van der Merwe et al, 1993;Coetzee et al, 1996). On the strength of the available scientific, pharmacological and clinical evidence, several patents have been registered on rooperol, and the extract has also been registered under the trade name of 'Harzol ™ ' in Germany for the treatment of prostate cancer (Pegel, 1979;Tyler, 1986;Drewes and Lieberg, 1987;Albrecht et al, 1995a;Nair et al, 2007a).…”