The Content of Phenolic Acids and Flavonols in the Leaves of Nine Varieties of Sweet Potatoes (Ipomoea batatas L.) Depending on Their Development, Grown in Central Europe

Abstract

The aim of the study was the qualitative and quantitative analysis of the bioactive components present in the leaves of 9 sweet potato cultivars grown in the moderate climate in Poland, which were harvested at different growth stages according to the BBCH (Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie) scale (14, 51, 89). It was found that sweet potato leaves contained 7 polyphenolic compounds, including 5 chlorogenic acids—neochlorogenic acid (5-CQA), chlorogenic acid (3-CQA), 4-cryptochlorogenic acid (4-CQA), 34-di-O-caffeoylqunic acid (3,4-CQA), 3,5-di-O-caffeoylqunic acid (3,5-CQA)—and 2 flavonoids, quercetin-3-O-galactoside (Q-3-GA) and quercetin-3-O-glucoside (Q-3-GL). Their content depended on the genotype of the examined cultivars and on the stage of leaf development. The mean content of the identified polyphenolic compounds in the examined cultivars ranged from 148.2 to 14.038.6 mg/100 g−1 DM for the leaves harvested at growth stage 14 according to the BBCH scale. In the case of leaves harvested at BBCH stage 51, the concentration of polyphenolic compounds ranged from 144.76 to 5026.8 mg/100 g−1 DM and at BBCH stage 89 from 4078.1 to 11.183.5 mg/100 g−1 DM. The leaves of the Carmen Rubin cultivar collected at stage 14 contained the highest amount of polyphenolic compounds, while Okinava leaves had the highest amount of these compounds at stage 51. The highest content of polyphenolic compounds in leaves at BBCH growth stage 89 was found in the Radiosa variety. The highest concentration levels were found for 3-CQA at all stages of leaf development. Significant correlations between polyphenol content and antioxidant activity measured by 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing/antioxidant power (FRAP) were found. The results of this experiment revealed that the growth stages and genetic properties of cultivars have a very significant influence on the content of phenolic acids and flavonols in sweet potato leaves. The results are innovative and can have a practical application, as the knowledge of the content of the substances under study makes it possible to determine the optimal management practice of sweet potato leaf harvest in order to obtain more top-quality raw material.

Joint Transcriptomic and Metabolic Analysis of Flavonoids in Cyclocarya paliurus Leaves

“…Krochmal-Marczak et al found that more flavonols were accumulated in mature leaves of sweet potato throughout the leaf growth period. 20 The secondary metabolite contents were related to leaf development and the synthesis rate and the activity of secondary metabolites decreased gradually with the development of leaves and cell proliferation. 21 The contents of six catechins were previously shown to be significantly different across five development periods in Camellia sinensis leaves, with the content of total catechins in tender leaves significantly higher than that in mature leaves.…”

An Evaluation of Phenolic Compounds, Carotenoids, and Antioxidant Properties in Leaves of South African Cultivars, Peruvian 199062.1 and USA's Beauregard

“…According to Jung et al (1), the compound most abundant in sweet potato leaves is 5neochlorogenic acid (5-CQA), and its amount depends on different cultivars. In contrast, Krochmal-Marczak (19) noted that the chlorogenic acid (3-CQA) was the dominant CQA derivative. Our study found 1,4-diCQA, 3,5-diCQA, and 3-CQA to be the dominant CQA derivatives in the leaves of all six sweet potato cultivars.…”

“…(16). The observed differences in phenolic components are likely due to the genetic composition of the varieties examined, the climate conditions, and the maturity of the leaves harvested in this study (19). The Supplementary Figures 1A-N shows the UV spectrum MS, MS/MS spectrum, and the chemical structures of the tentatively identified compounds.…”

Bioactive Compounds, Antioxidants, and Health Benefits of Sweet Potato Leaves

“…Among them, caffeic acid and caffeoylquinic acid derivatives, such as 4,5-di-O-caffeoylquinic acid, 3,4,5-tri-O-caffeoylquinic acid, 3-mono-O-caffeoylquinic acid, 3,4-di-O-caffeoylquinic acid, and 3,5-di-O-caffeoylquinic acid, are indicated as the main phenolic constituents in SPL [ 9 , 26 , 27 ]. These constituents are associated with the specific genotypes and the stages of leaf development [ 9 , 23 , 26 , 28 ]. The level of polyphenols in SPL varies among their varieties ranging from 0.3−13.5 g gallic acid equivalent (GAE)/100 g DW, which is 7–9 times higher than that levels found in grape seeds [ 29 ].…”