Flavonoids. Flavonoids are ubiquitous and have many functions in the biochemistry, physiology and ecology of plants (Xxxxxxx, 1996; Xxxxx and Xxxxxx, 2006), and they are important in both human and animal nutrition and health (Xxxxxxx and Xxxxxx, 1998; Xxxxxxxx, 2001). In cannabis, more than 20 flavonoids have been reported (Xxxxx and Xxxx, 1979, Vanhoenacker et al., 2002; ElSohly and Xxxxx, 2005) representing 7 chemical structures which can be glycosylated, prenylated or methylated (Figure 5) Cannflavin A and cannflavin B are methylated isoprenoid flavones (Xxxxxx and Xxxxxxx, 1996). Some pharmacological effects from cannabis flavonoids have been detected such as inhibition of prostaglandin E2 production by cannaflavin A and B (Xxxxxxx et al., 1986), inhibition of the activity of rat lens aldose reductase by C-diglycosylflavones, orientin and quercetin (Xxxxxxxx et al., 1976); other studies only suggest a possible modulation with the cannabinoids (XxXxxxxxxx and Xxxxxxxxxx, 2002). NH2 HOOC OH 3 OH 13 COSCoA OH OH 11 COSCoA OMe OH Malonyl-CoA 3X Phenylalanine
Flavonoids. Flavonoids are found primarily in the skins and grape seeds. Flavonoids can be further divided into several sub-groups like flavones, flavonols, dihydroflavanols, flavanols, and anthocyanidins, with the same skeleton but different oxidation state of their central pyran ring. The most common flavonoids in wine are flavonols, catechins (flavan-3- ols), and anthocyanins. Flavonoids are synthesized from the combination of the shikimic and polyketide pathway. Polymerization of polyhydroxy flavan-3-ol units, (+)- catechin and (-)-epicatechin, and their gallate esters produces oligomers and polymers called proanthocyanidins (often referred to as procyanidins). Even though procyanidins occur primarily as dimers in grapes (Xxxxxxx 2008), they tend to be polymerized and predominate in wine as condensed tannins (mid-size procyanidin polymers containing three to five subunits). In some cultivars, structural differences exist among skin, stem, and seed procyanidins. Also, there are considerable differences in types and concentrations between cultivars (Xxxxxxx et al. 2004). In grape seeds and skin, about twenty procyanidin dimmers and trimers have been identified (Xxxxxxxx et al. 1999). Seeds contained procyanidin of catechins, epicatechin, and epicatechin gallate units while grape skin and wine showed procyanidins mostly based on epicatechin and epigallotcatechin units (Xx Xxxxxxx-Xxxxxx et al. 2000). The total amount of procyanidins is reported to vary from 1.7 to 4.4 g/kg of berries in skin, 1.1 to 6.4 g/kg in seeds, and 0.2 to 1 g/kg in pulp (Mane et al. 2007). Anthocyanins, which are responsible for the red or pink color in grape berries, belong to the flavonoid family. They are glycosylated derivatives and their parallel aglycones are known as anthocyanidins. In V. vinifera, 3-monoglucosides are the major anthocyanins where glucose can be acylated by acetic, p-coumaric, and caffeic acid (Alcalde-Eon et al. 2006; Xxxxx et al. 2004). Some additional anthocyanins, like 3-caffeoylglucosides of peonidin, cyanidin and delphinidin, have also been reported in grapes using HPLC-MS (Xxxxx et al. 2004). The anthocyanin profiling can be use for the chemotaxonomic classification as the total amounts (from 500 mg/kg to 3 g/kg of berries) and proportions of the various anthocyanins are the characteristic of each variety (Xxxxxxx et al. 2006). Grape anthocyanin composition depends not only on the maturity but also different vine growing parameters like soil and climate together ...
