Luteolin structure

Tenerife and La Palma, revealed the existence of luteolin and an array of simple phenolic derivatives as well as three known phytosterols, B-amyrin, sitosterol, and stigmasterol. The phenols identified comprised a set of phenylpropanoids myristicin [566] (see Fig. 6.16 for structures 566-573), methyleugenol [567], todadiol [568], todatriol [569], crocatone [570], elemicin [571], apiole [572], and the coumarin scopoletin [573]. The occurrence of these compounds is recorded in Table 6.5. The differences between the two profiles were taken by Gonzalez and his co-workers... 

The above findings are supported in the other studies of the inhibitory effects of flavonoids on iron-stimulated lipid peroxidation. Quercetin was found to be an inhibitor of iron-stimulated hepatic microsomal lipid peroxidation (/50 = 200 pmol I ) [134]. Flavonoids eriodictyol, luteolin, quercetin, and taxifolin inhibited ascorbate and ferrous ion-stimulated MDA formation and oxidative stress (measured by fluorescence of 2,7,-dichlorodihydro-fluorescein) in cultured retinal cells [135]. It should be mentioned that in recent work Heijnen et al. [136] revised the structure activity relationship for the protective effects of flavonoids against lipid peroxidation. 

Series of cassiaoccidentalins built on a 6-C-(6-deoxy-ribo-hexos-3-ulosyl)flavone general structure, and isolated from Cassia — cassiaoccidentalin A 6-C-glycosyl 2 -0-rhamnosyl)apigenin B 6-C-glycosyl (2"-0-rhamnosyl)luteolin and C 6-C-glycosyl (2"-0-rhamnosyl)diosmetin. 

Flavones are structurally very similar to flavonols and differ only in the absence of hydroxylation at the 3-position on the C-ring. Flavones are mainly represented in the diet by apigenin and luteolin. Unlike flavonols, they are not widely distributed with significant concentrations being reported in only celery (Apium graveolens), parsley (Petroselinum crispum), and artichoke (Cynara scolymus) [Crozier et al., 2006a]. As a consequence their dietary intake... 

Figure 5.2 Structures of luteolin (L), kaempferol (K), and taxifolin (T). A comparison of the antioxidant (inhibition of MPO and radical scavenging activity) and anti-inflammatory (inhibition of LTB4) activity with that of quercetin (Q) is summarized.

The flavonoids, luteolin, luteolin 7-0-/3-d-xyloside and cynaroside, were isolated by El-Moghazi et al. (1979) and orientin and vitexin by Akunzemann and Herrmann (1977). Quercetin-3-glucuronide, rutin, isoorientin, isovitexin and apigenin-7-glucoside have been reported from aniseed (Ozguven, 2000). Figure 18.2 depicts the structure of flavonoids in aniseed. 

---