Variation of Flavonoid Content Among Sweetpotato Accessions

Abstract

<jats:p>The objective of this study was to characterize and quantify five commonly occurring flavonoids (quercetin, luteolin, apigenin, myricetin, and kaempferol) in storage roots and leaves of 10 sweetpotato [<jats:italic>Ipomoea batatas</jats:italic> L. (Lam.)] accessions: SC1149, ‘Excel’, ‘Vardaman’, ‘Hernandez’, ‘Picadito’, ‘Porto Rico’, ‘GA90-16’, PI531116, NC98-608 (Covington), and ‘Beauregard’ (B94-14-G2). The flavonoids were present in varying amounts (quercetin comprised greater than 79% and 55% of the mean flavonoid content in sweetpotato leaf and root samples, respectively) and were found to be more concentrated in the leaves (0.65% to 2.76% dry weight) than in the storage roots (0.27% to 1.69% dry weight). The results indicate significant variability in flavonoid content among different sweetpotato accessions, suggesting that there is the potential for genetic manipulation of sweetpotato to influence flavonoid content and profile through traditional breeding or biotechnological approaches.</jats:p>

Comparative analysis of phytochemicals and polar metabolites from colored sweet potato (Ipomoea batatas L.) tubers

“…Kaempferol and luteolin were the least abundant flavonoids in all samples analyzed, and luteolin was not detected in white-fleshed sweet potatoes. The flavonoid composition observed in this study was consistent with a previous report that the low relative kaempferol accumulation in the leaves and tubers of sweet potatoes may result from conversion of kaempferol to quercetin and myricetin because dihydrokaempferol is a dihydroquercetin and dihydromyricetin precursor (16). Anthocyanins in sweet potatoes were investigated by analyzing their hydrolytic products because complex glycoslyation patterns make identifying individual anthocyanins difficult, even by liquid chromatography-MS analysis (17).…”

“…It is difficult to predict flavonoid content based on color alone because only a few hundred flavonoids appear in the colored state among the thousands of flavonoids in plants. Anthocyanins are the most intensely colored flavonoid pigments and appear as red, purple, or blue in sweet potatoes (16). According to Montilla et al (19), sweet potato varieties can be classified into two groups based on the peonidin/cyanidin (p/c) ratio: cyanidin type (p/c <1.0), with a greater degree of blueness (blue-dominant group) and the peonidin type (p/c >1.0), with a greater degree of redness (red-dominant group).…”

Iron Bioavailability and Provitamin A from Sweet Potato- and Cereal-Based Complementary Foods

“…Ascorbic acid, β-carotene and fructose have been shown to improve the bioavailability of iron from foods [14,15,16], however, for ascorbic acid and fructose, this effect is dose dependent, affected by the food matrix, and diminished or eliminated by polyphenols [16,37,38]. Sweet potato has high concentrations of a range of different polyphenols [19,20], and although knowledge about the inhibitory effects of all the specific polyphenolic compounds in sweet potato is lacking, the results of this study suggest they are strong inhibitors of iron uptake. This is consistent with evidence demonstrating that polyphenols are potent inhibitors of inorganic iron absorption, and limit food iron bioavailability [21,22].…”

“…Sweet potato, however, is also a rich source of polyphenols [19,20]. Polyphenols are potent inhibitors of non-haem iron (inorganic iron and the most prevalent form in the diet) uptake, and may even inhibit absorption of haem-iron [21,22,23].…”

“…Studies have demonstrated that tannic acid (a commonly occurring dietary polyphenol) at a 0.1:1 tannin to iron molar ratio decreased iron uptake by almost 100% in the Caco-2 cell model [24], and a single meal study found that a tannic acid:iron 1:1 molar ratio led to almost 90% decreased iron absorption [25]. In addition, different sweet potato cultivars may contain different types of polyphenols [19,20]; the iron inhibitory effects of polyphenols vary with structure, thus knowing only total levels of food polyphenols may limit the ability to predict their effects on iron absorption [25,26,27]. …”