PHYTOCHEMISTRY MCQS
- 1. CHAP 1 CARDIAC GLYCOSIDES 1. describe the chemical structure of cardiac glycosides 2. T/F aglycones are of cardiac glycoside are cardenolide and bufadienolide where bufadienolide is more occurred in nature 3. T/F Aglycone of the cardiac glycosides are derived from mevalonic acid but the final molecules arise from a condensation of a C21 steroid with a C2 unit (the source of C-22 and C-23). 4. T/F Bufadienolides are condensation products of a C21 steroid and a C3 unit 5. T/F common to all the aglycones is the presence of two hydroxyl groups: one is a 3ļ¢ primary alcohol, the other is a 14ļ¢ secondary alcohol 6. T/F The A, B, C and D rings normally have a trans-trans-cis configuration and or less often, a cis-trans-cis configuration 7. T/F Conversion to A/B trans system leads to a marked drop in activity 8. T/F The activity is maximized when the A, B, C and D rings are in the cis, trans, cis configuration AND The C and D rings must be TRANS fused 9. T/F Aglycone lactone ring with C24 is know as cardenolide 10.T/F in cardica glycoside The sugar moiety is generally linked to the aglycone through the hydroxyl group at C-3 11.T/F The sugars cannot affect the activity of the glycosides.
- 2. 12.T/F The cardiac activity is linked to both the aglycone and glycone molecules 13.T/F The glycone participate directly in the activity by modifying the polarity of the compound. 14.T/F The lactone is at C-17 may be in the ļ¢ configuration 15.T/F The saturated 17-lactone plays an important role in receptor binding and unSaturation of the lactone ring dramatically reduced the biological activity. 16.T/F the substituents. The inversion of the configuration at C-3 diminishes the activity, but 3-deoxy compounds are not completely inactive. 17.T/F A skeleton without 14b-OH group but retaining the C/D cis ring fusion was found to loose activity. 18.T/F Comparison of digitoxin and digoxin structures reveals that they differ only by an extra OH group in digoxin at C-14, yet their partition coefficients differ by as much as 15 % points 19.T/F Lactones alone, when not attached to the steroid skeleton, are less active, thus the activity I shared with steroid glycone and aglycone. 20.What are the solvent used in cardiac glycoside extraction 21.What is importance of the lead acetate in extraction process 22.What solvent /reagent will help in obtain glycoside for further characterisation 23.T/F The chloroform is helpful to precipitate the impurity during extraction of the glycoside 24.T/F What is the best solvent for extraction of glycoside 25.T/F Characterisation depends only on the aglycone 26.T/F Reagent used in Raymond's test is methanolic alkali and Violet color confirms the presence of cardiac glycosides 27.T/F In large doses they are toxic and bring about cardiac arrest in systole, but in lower doses they are important drugs in the treatment of congestive heart failure.
- 3. 28.T/F Digoxin is indicated for edema ,heart failure and hypotension 29.T/F Cardiac glycosides inhibit the membrane bound proton pump responsible. 30.Describe The Action Mechanism Of Digitalis 31.T/F The glycosides are thought to act at the membrane level, by inhibition of the ATPase, which would result in an increase of the intracellular calcium ion concentration 32.T/F you can manage digitalis intoxication by calcium administration 33.T/F Rifampin decrease the digoxin concentration 34.T/F Itraconazole which slows down the metabolism of digoxin 35. T/F Quinidine increase concentration of digitalis by inhibition of P-glycoprotein 36.T/F 5 g of powdered leaf of purple foxglove in 100 ml of water are used as infusion 37.T/F Purple foxglove is indicated for the skin ulcer and scar wound 38.T/F Digitoxin is most widely used of the cardiotonic glycosides obtained from D. purpurea, D. lanata WHILE Digoxin is a cardiotonic glycoside obtained from the leaves of D. lanata. 39.T/F Digoxin is the most lipid-soluble of the cardiac glycosides used in therapeutics while Digitoxin is a highly potent drug and should be handled with exceptional care 40.T/F The major pharmacokinetic parameters for digitoxin include incomplete oral absorption about 8o% hile digoxin is completely aborbed and quickly eliminated 41.TF Digoxin may be indicated in patients with impaired renal function while Digitoxin should cause harms 42.T/F Digoxin is indicated when the risk of digitalis intoxication is great, since it is relatively short-acting and rapidly eliminated when compared with Digitoxin 43.T/F Bufadienolides are therapeutically much valued even though therapeutic index is low and produce more side effect and it is widely used in the treatment of cough.
- 4. CHAP 2: SAPONIN GLUCOSIDES 1. T/F Saponins constitute a vast group of organic compounds that form persistent froth when shaken with water 2. T/F Saponins cause hemolysis of white blood cells, it means that injection into the blood stream are more or less toxic. 3. T/F Saponins are very harmful when taken orally and more or less toxic as IV injection 4. Briefly describe the classification of Saponins 5. List 10 properties of Saponins 6. What is the suitable solvent for Saponins extraction= water, alcohol methanol, ethanol or hydroalcoholic 7. Why free drying is not much applicable in Saponins extraction=cause hydrolysis of bidesmonsides 8. How the fat are separated from saponin =by use petroleum ether 9. What is the importance of treatment of the sample by HCl= to neutralize esterase enzyme 10.What is the most useful alcohol in separation of water soluble compound and Saponins = N-butanol
- 5. 11.How the saponin will be obtained= precipitate it by organic solvent then conduct filtration to get precipitates 12.Pentacyclic Triterpenoid Saponins contain 30 carbons 13.Pentacyclic Triterpenoid are rare in dicots and common in monocots 14.Strophanthus and Digitalis contain both steroidal Saponins and cardiac glycosides 15.Steroidal Saponins are both in monocots and dicots 16.Steroidal Formed via the mevalonic acid pathway. 17.Therapeutic properties of saponin , discuss 18.What is the cause of hemolysis of RBC by saponin = detergent properties CHAP 3: QUINONES O O O O OH HHH OH O O H 10 Antraquinone Reduction Oxidation Oxanthrone Anthrone Anthranol Dimerisation dianthrone Reduction Oxidation Reduction Oxidation 1. T/F Simple benzoquinones are specific to Arthropoda and rarely found in high plants.
- 6. 2. T/F Biosynthesis of quinones is done by different metabolic pathways from a limited number of precursorās acetate, mevalonate and phenylalanine 3. T/F Quinones with one aromatic ring is known as benzoquinones 4. T/F The quinones with two aromatic rings are known as anthraquinones 5. Discuss the properties of qunonoes 6. T/F Anthranol is a mediator of dianthrone and anthraquinone 7. T/F Oxidation of the anthraquinone yield oxanthrone 8. T/F Actually natural benzoquinones have therapeutics application and they occur as glycoside some of them like arbutin possesses strong urinary antiseptic activities 9. T/F Glycosides of anthranols and anthrones have a more drastic action than anthraquinone glycosides 10.T/F as laxatives, cathartics, anti-inflammatory, antibacterial, antifungal & natural dyes 11.T/F Some quinones serve as electron acceptors in electron transport chains such as those in photosynthesis (plastoquinone, phylloquinone), and aerobic respiration (ubiquinone). Phylloquinone is also known as Vitamin D1 as it is used by animals to help form certain proteins, which are involved in blood coagulation, bone formation, and other processes CHAP 4: ANTHRAQUINONE GLYCOSIDE
- 7. 1. T/F Anthraquinone are characterized by presence of phenolic and glycosidic compounds, derived from anthracene and have various degree of oxidation. 2. T/F They have in common a double oxidation at C1 & C8. 3. T/F Anthraquinone glycosides upon hydrolysis yield aglycone, which are di, tri or tetra hydroxy anthraquinone or derivative of these compound 4. T/F o-succinylbenzoic acid (OSB) (the most common pathway in higher plants , OSB arise from the reaction of isochorismic acid with Ī±-ketoglutaric acid in the presence of thiamine pyrophosphate (TPP). 5. T/F Anthranonls and Anthrones are educed anthraquinone derivatives that Occur only as glycosides. 6. T/F Anthranol is pale yellow, non-soluble in alkali, non-fluorescent while Anthrone is brown-yellow, soluble in alkali, strongly fluorescent 7. T/F Anthronols and anthrone are the isomers of each other 8. T/F The quantification of free forms of quinones is useful as they have significant therapeutic activity. 9. T/F Combined form and free form of the quinones are separated from each other using the non-polar organic solvent where the free form are occurred in aqueous phase and combined form occur in non-polar organic solvent. 10.T/F Herbal anthraquinones are possibly the most important herbal factors that exert an action of irritation over your gastrointestinal system 11.T/F anthraquinone laxative herbs possess qualities of āsacral irritantsā and hence contraindicated in pregnancy, Senna has been shown to be very safe in pregnancy and lactation 12.T/F The long term use of the anthraquinone glycoside induce the constipation 13.Stimulant laxative should not be done to patient suffering from spastic colon. 14.Aloe gel has laxative effect and is used in cosmetic, and topical products 15.Aloe gel has, interesting effects in treatment of asthma, peptic ulcers, hairloss, as spermicide and as a cancer chemo-preventive agent 16.Aloe gel components inhibit the pain & promote wound healing also stimulates fibroblast and connective tissue formation
- 8. 17.T/F Senna is manly used to treat constipation by stimulating of intestinal peristalsis, flushing out the toxins from the body 18.T/F Senna laxative effect is attributed mainly to āthe anthraquinone glycosides, especially sennoside A and B 19.T/F The metabolism of the anthraquinone glycosides in the digestive tract can occur in SINGLE ways. REAGARDING SENNA MECHANISM 20.T/F The glycosides are not absorbed in the upper gut but are converted by the microflora of the large intestine into active aglycones, principally Rhein anthrone, which exerts a laxative effect on the colon 21.T/F Alternatively, in the presence of bile and the sugar, the free aglycone can be absorbed into the blood stream and secreted later into the colon. 22.T/F The final result is stimulation of the Auerbach plexus (myenteric) resulting in increased intestinal muscle contraction, Moreover, its mucilage content decreases absorption of fluid leading to an enhancement of the final laxative action. 23.T/F Pregnant, nursing or menstruating women should use Senna, but it is not appropriate for children under twelve years of age 24.T/F Long time use of Senna are responsible of severe constipation and can provoque heart failure
- 9. 26.T/F Rhubarb at the doses of 1g is used as laxative 27.T/F Rhubarb at doses of 3g is used as purgative 28.T/F Rumex abyssinicus, In Rwanda, the leaf of the plant is traditionally used to treat malaria, gonorrhoea, constipation, poisoning, hepatitis, constipation and sciatic neuralgia. 29.T/F Rumex abyssinicus , in Rwanda The root is used to treat coughs and gastric ulcers CHAP 5: CYANOGENIC GLYCOSIDE 1. T/F The cyanogenic or cyanogenetic glycosides may be defined chemically as glycosides of beta hydroxynitriles and belong to the secondary metabolites of plants 2. T/F All cyanogens are amino acid-derived plant constituents and are always glycosides of 2-hydroxynitriles 3. T/F The combination of cyanogenic and cyanidrins is the means by which cyanogenic plants are protected against predators. 4. T/F Upon consumption of a cyanogenic plant, Ī²-glycosidase (a part of bacterial microflora in GIT of mammals) will be released during digestion and remain active until deactivated by the low pH of the stomach thus enzyme will
- 10. hydrolyse the cyanogenic glycoside and release at least part of the potential hydrogen cyanide content of the plant. 5. T/F cyanogenic plants are characterised by free HCN in normaal plant tissues 6. T/F The plant injuries like mechanical damage should be the sources of release of cyanide due cyanogenās and hydrolytic enzymes contact. 7. T/F Beans and sorghum should be ones of cyanogen sources 8. T/F The biosynthetic precursors of the cyanogenic glycosides are different D- amino acids, which are hydroxylated, then the N-hydroxylamino acids are converted to aldoximes and these are converted into nitriles and hydroxylated to Ī±-hydroxynitriles and then glycosylated to cyanogenic glycosides 9. T/F All known cyanogenic glycosides are ALPHA-linked, mostly with D-glucose 10.T/F Aglycones are formed by Ī±-hydroxynitriles, which are stabilised by glucosyl bound to hydroxyl group of a sugar. 11.T/F The sugar residue is almost always D-glucose joined by an 0-beta-D- glucosyl linkage REGARDING THE MECHANISM OF ACTION OF CYANOGENIC GLYCOSIDE 12.T/F Hydrogen cyanide inactivates the enzyme cytochrome oxidase in the mitochondria of cells by binding to the Fe3+ /Fe2+ contained in the enzyme then provoque a decrease in the utilization of oxygen in the tissues.
- 11. 13.T/F Cyanide causes a decrease in blood glucose and lactic acid levels and a decrease in the ATP/ADP ratio indicating a shift from aerobic to anaerobic metabolism. 14.T/F Cyanide activates glycogenolysis and shunts glucose to the pentose phosphate pathway decreasing the rate of glycolysis and inhibiting the tricarboxylic acid cycle 15.T/F Hydrogen cyanide will reduce the energy availability in all cells, but its effect will not affect the respiratory system and heart 16.T/F In blood hydrogen cyanide binds to iron in both haemoglobin and methaemoglobin and forms cyanmethaemoglobin and cyanhaemoglobin respectively 17.T/F The affinity of hydrogen cyanide to haemoglobin is used for treatment 18.T/F Cyanides and cyanic acid act as neurotoxins and they also bind to several proteins damaging enzyme systems 19.T/F In chronic poisoning we can see increased respiration due to āchemoreceptorsā and respiration centre damage Regarding cyanide biotransformation 20.T/F The major defence of the body to counter the toxic effects of cyanide is its conversion to thiocyanate mediated by the enzyme rhodaminase 21.T/F limiting factor for the conversion of cyanide is thiosulphate 22.T/F dietary sulphur amino acids such as methionine and cysteine are important in detoxification of cyanides 23.T/F cyanide may combine with niacin (vitamin B6) in detoxification to enhance the of cyanide via urine and bile 24.T/F cysteine may react indirectly with the cyanide to form 2-imino-thiazolidine- 4-carboxylic acid, which is excreted in the feces and urine 25. T/F A minor amount may be converted into formic acid, which may be excreted in urine.
- 12. 26.T/F methaemoglobin effectively competes with cytochrome oxidase for cyanide, and its formation from haemoglobin, effected by sodium nitrile or amylnitrite, is exploited in the treatment of cyanide intoxication 27.Briefly describe the mechanisms of dissociation of cyanide from cyanogenic glycosides. 28.T/F Administration of nitrites ā formation of methaemoglobin, which binds cyanides ā formation of cyanmethaemoglobin ā administration of thiosulphates ā cyanides released from methaemoglobin react with them and form thiocyanates 29.Lethal dose for humans is 0.5 ā 3.5 mg/kg HCN 30.Plants detoxify HCN by conversion into Asparagine and beta-cyanoalanine 31.T/F Garificationā, a process whereby fermented and dried cassava mash is simultaneously cooked and dried in a shallow wok, resulted in a 90-93% reduction in total cyanogen content . 32.T/F Overall, traditional African processes typically decrease the cyanogen content of cassava by 97-99%. 33.T/F Plants with 20 mg HCN /100 g fresh weight are considered as toxic and few cultivator exceed this value 34.T/F A part of ingested linamarin in cassava products has been found to pass through the human body unchanged and it is excreted in the urine within 24 hours in both humans and rodent 35.T/F Less than one-half of orally ingested linamarin is converted to cyanide and hence thiocyanate, about one-quarter is excreted unchanged and another quarter is metabolized into an as yet unknown compound. 36.T/F Apricot pits are rich in amygdalin, ground up for preparation of laetrile, a controversial cancer treatment 37.T/F Eating fruits and vegetables that contain beta-glucosidase (such as celery, peaches, bean sprouts, and carrots) may increase the risk of cyanide poisoning Traditionally, the steps of bamboo shoots preparation are: ļ· fresh bamboo shoots are cut in half lengthwise; ļ§ the outer leaves are peeled away and any fibrous tissue at the base is trimmed; ļ· the bamboo shoot is thinly sliced into strips; ļ· the shoots are boiled in lightly salted water for 8-10 minutes.
- 13. 38.T/F Bamboo shoots may contain as much as 1000 mg/kg hydrogen cyanide, significantly higher than the amounts detected in cassava tubers, however, the cyanide content is reported to decrease substantially following harvesting 39.T/F The concentration of cyanide in the immature shoot tip of bamboo is approximately 8000 mg/kg of hydrogen cyanide and in the apical part of bamboo shoots may contain as much as 1000 mg/kg of hydrogen cyanide. 40.Briefly and traditionally , discuss the step of bamboo shoot preparation 41.T/F Konzo is an upper motor neuron disease that causes reversible paralysis of the legs mainly in children and young women,1,2 due to consumption of large amounts of cyanogens from poorly processed cassava, the staple food of tropical Africa 42.T/F Tropical Ataxic Neuropathy affects males and females in all age groups equally Chap 6 thiocyanate glycosides 43.T/F Thiocyanate is toxic to many microorganisms at relatively low cyanide concentrations 44.T/F Self-plant damaging should occur once the glucosinolates are in contact with myrosinase enzyme 45.T/F Glucosinolates are classified into 3 class which are Aliphatic glucosinolates ,aromatic glucosinolates and indole glucosinolates 46.T/F After myrosinase activity, the remaining molecule then quickly converts to a thiocyanate, an isothiocyanate or a nitrile; these are the active substances that serve as defense for the plant
- 14. 47.T/F Isothiocyanates are irritating to mucous membranes and not readily consumed in sufficient quantities to be toxicity but they can have powerful antithyroid effects and interfere with the synthesis of necessary thyroid hormones. 48.T/F Oxazolidine-2-thiones depress growth and increase the incidence of goiters. They inhibit thyroid function by blocking the incorporation of iodine into thyroxine precursors and by suppressing thyroxine secretion from the thyroid. 49.T/F Nitriles: depress growth, cause liver and kidney lesions, and in severe cases leading to liver necrosis, bile duct hyperplasia, and megalocytosis of tubular epithelium in the kidney. 50.T/F Thiocyanates: inhibit iodine uptake by the thyroid leading to reduced iodination of tyrosine, resulting in decreased production of the important thyroid hormone thyroxine 51.T/F Glucosinolates are destroyed by hydrolytic enzymes called myrosinase and is not always present in plants containing glucosinolates 52.T/F In normal conditions, thiocyanates and Isothiocyanates are formed; under pH 7, nitriles and elementary sulphur are established 53.T/F Glucosinolates are heat-stable, so cooking is less important in food processing for reducing glucosinolates 54.T/F Goitrin, a breakdown product of glucosinolates, interferes with iodine uptake in to thyroid gland (blocks it), it is so called strumigen
- 15. 55.T/F Decrease intake of glucosinolates leads to increased activity of thyroid gland, which has to catch iodine more carefully, cells of its epithelium grow and hypertrophy follows Struma is formed. 56.T/F About 120 different glucosinolates are known to occur naturally in plants 57.T/F The species in which glucosinolates occur that are important for animal or human feeding belong to the family Brassicaceae 58.T/F Isothiocyanates and oxazolidine-2-thiones have been shown to have effects on the thyroid gland in animals and these effects occur even if iodine is sufficient. 59.T/F Isothiocyanates, nitriles and indole products can all be further degraded to produce the thiocyanate ion. This compound is able to cause goitre in humans when dietary iodine is insufficient 60.T/F there is no evidence to support a causative role for dietary glucosinolates in human goitre 61.T/F have been shown to induce the activity of the phase II detoxification enzymes and inhibit phase I (activating) enzymes, exerting an anticancer effect 62.Cooking of glucosinolates by boiling will reduce exposure through leaching of glucosinolates into water and inactivation of myrosinase CHAP 7 ALKALOID