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Questions and Answers
What is one of the mechanisms by which quercetin aids in the prevention of peptic ulcers?
What is one of the mechanisms by which quercetin aids in the prevention of peptic ulcers?
How does oxidative LDL (oxLDL) contribute to atherosclerosis?
How does oxidative LDL (oxLDL) contribute to atherosclerosis?
Which statement best describes the effect of flavonoids on LDL oxidation?
Which statement best describes the effect of flavonoids on LDL oxidation?
What role does the D-alanine- D-alanine ligase (Ddl) enzyme play concerning H.pylori?
What role does the D-alanine- D-alanine ligase (Ddl) enzyme play concerning H.pylori?
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What is a primary risk factor for the development of atherosclerosis?
What is a primary risk factor for the development of atherosclerosis?
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What effect do flavonoids like quercetin have on the inflammatory response?
What effect do flavonoids like quercetin have on the inflammatory response?
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Which of the following is a result of oxidized LDL accumulation in the arteries?
Which of the following is a result of oxidized LDL accumulation in the arteries?
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Which of the following factors does NOT increase levels of oxidized LDL?
Which of the following factors does NOT increase levels of oxidized LDL?
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What is one potential consequence of oxidized LDL accumulation in the arteries?
What is one potential consequence of oxidized LDL accumulation in the arteries?
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Which flavonoid is specifically mentioned as having hepatoprotective activity?
Which flavonoid is specifically mentioned as having hepatoprotective activity?
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Study Notes
Biochemistry of Natural Products, Lecture 3: Flavonoids
- Flavonoids are polyphenolic secondary plant metabolites.
- They comprise 15 carbons (2 aromatic rings connected with a 3-carbon bridge) and numerous hydroxyl groups (OH).
- Flavonoids exhibit antioxidant properties by acting as free radical scavengers, singlet oxygen quenchers, hydrogen donors, and metal chelators.
- Flavonoid sources include fruits and vegetables, tea, red wine, citrus fruits, cocoa, and berries. Specific flavonoid types within these sources include: flavanols, flavonols, flavanones, isoflavones, and anthocyanins (depending on the food type).
- Flavonoids have several important biological properties.
- Anti-ulcer effects: promote mucus secretion and inhibit H. pylori bacteria.
- Anti-atherosclerotic effects: suppress LDL oxidation and inflammatory progression in arteries. Elevated LDL is a primary risk factor for atherosclerosis and coronary artery disease. Oxidized LDL reacts with free radicals, becoming more reactive and causing tissue damage; it also attracts immune cells (e.g. macrophages) and platelets to the damaged area exacerbating the process.
- Anti-inflammatory effects: inhibit the cyclooxygenase (COX) pathway and inflammatory mediators like arachidonic acid.
- Hepatoprotective activity: many flavonoids (e.g., silymarin, apigenin, quercetin, naringenin) protect the liver.
- Memory improvements: through various mechanisms like anti-neuroinflammatory actions, reducing metal ion neurotoxicity, promoting autophagy, reducing oxidative stress, mitigating mitochondrial dysfunction, and reducing amyloid-β and tau levels.
Physicochemical Properties, Extraction, Characterization, and Quantification
- Flavonoid glycosides are water-soluble and soluble in alcohols.
- Glycosides are extracted primarily using acetone or alcohols (ethanol, methanol) mixed with water, often at high temperatures.
- Aglycones are soluble in apolar organic solvents (like dichloromethane).
Extraction and Characterization of Flavonoids
- Extraction methods include maceration, Soxhlet, ultrasound-assisted extraction (UAE), supercritical fluid extraction (SFE), and accelerated solvent extraction (ASE).
- Chromatographic techniques (HPLC, TLC) are used for analysis.
Detection and Quantification of Flavonoids
- Flavonoids can be identified and quantified using various chemical tests.
- Shinoda, Vanillin-HCl, Zinc, and Ammonia tests produce specific color changes in the presence of flavonoids.
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Description
Explore the fascinating world of flavonoids in this quiz from Lecture 3 of the Biochemistry of Natural Products. Learn about their chemical structure, antioxidant properties, sources, and significant biological effects. Assess your knowledge and understanding of these essential plant metabolites.