Fruit and vegetable intake has been associated with a reduced risk of cardiovascular disease. Quercetin and kaempferol are among the most ubiquitous polyphenols in fruit and vegetables. Most of the quercetin and kaempferol in plants is attached to sugar moieties rather than in the free form. The types and attachments of sugars impact bioavailability, and thus bioactivity. This article aims to review the current literature on the bioavailability of quercetin and kaempferol from food sources and evaluate the potential cardiovascular effects in humans. Foods with the highest concentrations of quercetin and kaempferol in plants are not necessarily the most bioavailable sources. Glucoside conjugates which are found in onions appear to have the highest bioavailability in humans. The absorbed quercetin and kaempferol are rapidly metabolized in the liver and circulate as methyl, glucuronide, and sulfate metabolites. These metabolites can be measured in the blood and urine to assess bioactivity in human trials. The optimal effective dose of quercetin reported to have beneficial effect of lowering blood pressure and inflammation is 500 mg of the aglycone form. Few clinical studies have examined the potential cardiovascular effects of high intakes of quercetin- and kaempferol-rich plants. However, it is possible that a lower dosage from plant sources could be effective due to of its higher bioavailability compared to the aglycone form. Studies are needed to evaluate the potential cardiovascular benefits of plants rich in quercetin and kaempferol glycoside conjugates.

The ramp (Allium tricoccum) is a traditional plant in the eastern Appalachian Mountains. Ramps have been used in traditional medicine for their health-promoting roles in lowering blood pressure and cholesterol. Information on the chemical composition of the potentially bioactive components in ramps is limited. Therefore, the aim of this work was to characterize and quantify major flavonols in ramps. Flavonoids were extracted in 50% methanol and 3% acetic acid. Characterization was conducted using UHPLC-PDA-MS and MS/MS, and quantification was performed using UHPLC-PDA detection. The major flavonol glycosides were kaempferol sophoroside glucuronide, quercetin sophoroside glucuronide, kaempferol rutinoside glucuronide, quercetin hexoside glucuronide, quercetin sophoroside, and kaempferol sophoroside. All conjugates were detected in leaves. Quercetin and kaempferol sophoroside glucuronide conjugates were detected in the stem, but no flavonol glycosides were detected in the bulb. The total amounts of the identified quercetin and kaempferol conjugates in whole ramps were 0.5972 ± 0.235 and 0.3792 ± 0.130 mg/g dry weight, respectively. Flavonol conjugates were concentrated in the leaves. To our knowledge, this work is the first to identify and quantify the major flavonol glycosides in ramps. Our findings suggest that specifically the leaves may harbor the potentially bioactive flavonols components of the plant.

Ramps (Allium tricoccum) is a traditional plant in the eastern Appalachian Mountains. Ramps have been used in Appalachian folk medicine for its health promoting roles in lowering blood pressure and cholesterol. Information on the chemical composition of bioactive components responsible for the potential health benefits are scarce. Analysis of the chemical composition in similar Allium plants showed that flavonols, induced similar health benefits. Therefore, the aim of this work is to characterize major flavonol conjugates in ramps. The secondary aim is to develop a preliminary quantification protocol. Flavonol glycosides were extracted in 50% methanol and 3% acetic acid. Characterization of flavonol glycosides was conducted using UHPLC-PDA-MS 2. For acid hydrolysis protocol, flavonol glycosides extracts or plant tissues were hydrolyzed by different concentrations of HCl. UHPLC-PDA was used to detect hydrolyzed flavonols. Characterization showed that the major putative flavonol glycosides were kaempferol sophoroside glucuronide, quercetin sophoroside glucuronide, and quercetin dihexoside. The different parts of the putative structures were preliminarily confirmed using 1 H and C 13 NMR analysis. The identified flavonol glycosides were concentrated in leaves. Preliminary quantification protocol showed that optimal hydrolysis conditions of flavonol conjugates was achieved by hydrolyzing the glycosides extract under 3M and 4M HCl, respectively, at 90 O C for two hours. To our knowledge, this work is the first to identify major flavonol glycosides content in ramps and develop a preliminary quantification protocol. This finding might explain the past usage of ramps as a medicinal plant. iii ACKNOWLEDGMENTS This work wouldn't be possible without the guidance and contribution of several people. First, I would like to express the deepest appreciation and gratitude to my committee chair, Dr. Melissa Ventura-Marra for her endless support during my educational journey. I am grateful for all the knowledge, experiences, passion, encouragement, and learning opportunities she provided. It was a great honor and pleasure to be a member of her research group. My words can't thank her enough for gifting me an unforgettable and invaluable journey. Also, I would like to extend my gratitude to my committee members Dr. Nikola Kovinich and Dr. Callee Walsh for their help on each step of the project. I have gained an enormous amount of knowledge in a new advanced field of research from their experiences. I appreciate their time and efforts on this project. My sincere thanks also go to Dr. Novruz Akhmedov for all the time, effort and expertise he provided on this work. His passion, assistance, and encouragement are invaluable. In a short period of time, he has provided a significant guidance and contribution on the project which are truly appreciated. I would also like to thank my research teammates for the help and all the insightful discussions. Also, I extend my appreciation to Denzil Blosser and Suzan Slider for all the help provided d...