Phytochemistry and Primary Metabolites

Comprehensive practice flashcards covering phytochemistry, primary vs secondary plant metabolism, proteins, fixed oils, and carbohydrate chemistry based on the lecture notes.

What is phytochemistry?

Phytochemistry is the branch of science concerned with the study of naturally occurring chemical compounds produced by plants (phytochemicals).

What are the primary reasons plants produce phytochemicals?

Plants produce phytochemicals for defense against herbivores, protection against microorganisms, protection from UV radiation, attraction of pollinators, seed dispersal, plant communication, adaptation to environmental stress, antioxidant protection, allelopathy, and wound healing or tissue repair.

What is the medicinal use of the phytochemical morphine?

Morphine is used as an analgesic.

What is the medicinal use of thymol?

Thymol is used as an antiseptic.

What is the medicinal use of flavonoids?

Flavonoids are used as antioxidant supplements.

What is the medicinal role of salicylic acid?

Salicylic acid serves as a precursor of aspirin.

What is the medicinal use of artemisinin?

Artemisinin is used as an antimalarial.

What is the medicinal use of paclitaxel (Taxol)?

Paclitaxel (Taxol) is used as an anticancer agent.

How are the cell contents of medicinal plants broadly classified?

They are classified into food storage products (primary metabolites) and by-products of metabolism (secondary metabolites).

How do primary metabolism and secondary metabolism differ in terms of plant necessity and occurrence?

Primary metabolism involves basic metabolic processes essential for survival, growth, and reproduction, occurring in all plants. Secondary metabolism produces specialized natural products that provide ecological advantages (like defense) rather than direct survival, and is species- or family-specific.

How do primary and secondary metabolites compare in plant quantity and commercial importance?

Primary metabolites are usually produced in large amounts and have mainly nutritional and structural commercial importance. Secondary metabolites are usually produced in smaller amounts and serve as major sources of medicinal drugs, flavors, fragrances, pesticides, and dyes.

What roles can primary metabolites play in pharmaceutical applications?

They can act as active pharmaceutical ingredients, replacement therapies, nutritional products, pharmaceutical excipients, and drug-delivery materials.

How are modern primary metabolite medicines typically formulated and administered?

Current medicines are usually purified, standardized, recombinant, or chemically modified, and are rarely administered as crude biological material.

What is the chemical definition of proteins?

Proteins are high-molecular-weight nitrogen-containing compounds composed of amino acids linked together by peptide bonds through the removal of water (condensation).

How are reserve proteins commonly stored within plant cells?

They are commonly stored as aleurone grains, which appear as amorphous masses or small particles within cells.

How can proteins be identified microscopically in plant tissues?

Microscopically, proteins can be identified using picric acid, which stains both the protein ground substance and crystalloid portions of aleurone grains yellow.

What is the natural source and therapeutic use of bromelain?

Bromelain is obtained from pineapple stems and is used for wound healing and as an anti-inflammatory agent.

What is the natural source and therapeutic use of papain?

Papain is derived from papaya latex and is used for enzymatic debridement.

What is the natural source and therapeutic use of asparaginase?

Asparaginase is sourced from $Escherichia\,coli$ and $Erwinia\,\text{spp.}$ and is used to treat leukemia.

What is the therapeutic indication for alteplase (tPA)?

Alteplase (tPA) is a recombinant human protein used for thrombolysis.

What is the chemical nature of fixed oils?

Fixed oils are esters of glycerol and long-chain fatty acids (triglycerides) such as stearic, oleic, linoleic, and ricinoleic acids.

What is the major fatty acid in castor oil ($Ricinus\,communis$) and its main clinical use?

The major fatty acid is ricinoleic acid, and its main clinical use is as a stimulant laxative and pharmaceutical vehicle.

What is the major fatty acid in olive oil ($Olea\,europaea$) and its main clinical use?

The major fatty acid is oleic acid, used for cardiovascular health and as an emollient.

What major fatty acid is found in evening primrose oil ($Oenothera\,biennis$)?

It contains $\gamma\text{-Linolenic acid (GLA)}$, used adjunctively in inflammatory skin conditions.

How do fixed oils differ from volatile oils in the filter paper test?

Fixed oils leave a permanent greasy stain on filter paper, whereas volatile oils leave only a temporary stain that disappears upon evaporation.

How do fixed oils and volatile oils differ regarding saponification?

Fixed oils undergo saponification with $KOH$ to produce glycerol and soaps, whereas volatile oils do not undergo saponification because they contain no glycerides.

What is the empirical formula for carbohydrates, and what are exceptions to this formula?

The empirical formula is $(CH_2O)_n$ (such as $C_5H_{10}O_5$ when $n = 5$), but exceptions include deoxy sugars and amino sugars.

What is the simplest aldose sugar?

$D\text{-glyceraldehyde}$ is the simplest aldose (an aldotriose).

What three types of structural representations are used for sugars?

Sugars are represented by Fischer projections (straight chain), Haworth projections (simple ring in perspective), and conformational representations (chair and boat configurations).

In what two cyclic forms can $D\text{-glucose}$ cyclize?

$D\text{-glucose}$ can cyclize to form either furanose or pyranose structures.

What are the three types of oxidation products formed from aldoses?

1. Aldonic acids (aldehyde converted to carboxyl group)
2. Uronic acids (primary alcohol oxidized to carboxyl group while aldehyde remains intact)
3. Saccharic acids / glycaric acids (oxidation at both ends)

How does glucose oxidase function in glucose measurement test strips?

Glucose oxidase converts glucose to gluconic acid and hydrogen peroxide. In the presence of peroxidase and $o\text{-dianisidine}$, a yellow color forms, forming the basis for measuring urinary and blood glucose.

What sugar alcohol is formed by reducing $D\text{-mannose}$, and what is its clinical use?

Reduction of $D\text{-mannose}$ forms mannitol, which is used as an osmotic diuretic.

How is sorbitol converted to drugs used in treating angina?

Sorbitol is dehydrated to $1,4,3,6\text{-dianhydro-D-sorbitol}$ (isosorbide), which is then nitrated to ISDN and ISMN, both used to treat angina.

What is 2'-deoxy ribose and where is it found?

It is a ubiquitous deoxy sugar that lacks a hydroxyl group and serves as the sugar component found in DNA.

What monosaccharides are released upon hydrolysis of maltose, lactose, and sucrose?

Maltose hydrolyzes to 2 molecules of $D\text{-glucose}$; lactose hydrolyzes to one glucose and one galactose; sucrose hydrolyzes to one glucose and one fructose.

What happens to the optical rotation when sucrose is hydrolyzed?

Hydrolysis of sucrose ($+66.5^\text{o}$) yields an invert sugar mixture of glucose ($+52.5^\text{o}$) and fructose ($-92^\text{o}$).

What chemical structure and linkage define lactose?

Lactose consists of $\beta\text{-D-galactose}$ joined to $\alpha\text{-D-glucose}$ via a $\beta(1,4)$ linkage.

What is lactulose, and what are its primary medical uses?

Lactulose is a semi-synthetic disaccharide (galactose-$\beta\text{-(1,4)-}$fructose) that is not absorbed in the GI tract; it is used as a laxative (Chronulac) or in managing portal systemic encephalopathy (Cephulac) by converting to acids that remove ammonia.

What is cellobiose and how is it obtained?

Cellobiose consists of 2 molecules of glucose linked by a $\beta(1,4)$ glycosidic bond and is usually obtained by the partial hydrolysis of cellulose.

What are the oligosaccharide definitions for raffinose, stachyose, verbascose, and ajugose?

Trisaccharide raffinose (glucose, galactose, fructose); Tetrasaccharide stachyose (2 galactoses, glucose, fructose); Pentasaccharide verbascose (3 galactoses, glucose, fructose); Hexasaccharide ajugose (4 galactoses, glucose, fructose).

What is the composition of starch?

Starch is composed of $10\text{--}30\%$ $\alpha\text{-amylose}$ and $70\text{--}90\%$ amylopectin.

What is cellulose chemically, and what organisms can digest it?

Cellulose is a polymer of $\beta\text{-D-glucose}$ attached by $\beta(1,4)$ linkages and is only digested and utilized by ruminants (such as cows, deer, giraffes, and camels).

What are the pharmaceutical uses of microcrystalline cellulose and cellulose acetate phthalate?

Microcrystalline cellulose is used as a binder-disintegrant in tablets, while cellulose acetate phthalate is used for enteric coating.

What are the structural features and iodine reaction of glycogen?

Glycogen (animal starch) contains $\alpha(1,4)$ links with $\alpha(1,6)$ branches every $8\text{ to }12$ glucose units, and gives a red-violet color with iodine.

What is inulin, and what is its main clinical application?

Inulin consists of $\beta(1,2)$ linked fructofuranoses (linear only, no branching) that colors yellow with iodine; it is used as a diagnostic agent to evaluate glomerular filtration rate (GFR).

Where is chitin found in nature, and how is it used commercially in foods?

Chitin is found in fungal cell walls and exoskeletons of crustaceans, insects, and spiders. Commercially, it is used in coatings to extend shelf life of fruits and meats, and a chitin derivative binds iron to slow meat rancidity.

How do glycoproteins and proteoglycans differ in composition?

In glycoproteins, protein content is far greater than carbohydrate (protein >>> carbohydrate) and saccharides lack serial repeating units. In proteoglycans, carbohydrate content is far greater than protein (carbohydrate >>> protein) and contains serial repeating units.

What are pectins and what is their primary commercial use?

Pectins are heteropolysaccharides found in fruit pulp (citrus, apples) composed of galactans and arabans; they yield galacturonic acid, galactose, arabinose, methanol, and acetic acid on hydrolysis and are used as gelling agents.

What is the botanical source and pharmaceutical utility of gum arabic?

Gum arabic (gum acacia) is harvested from acacia trees in Sudan, Somalia, and Senegal; it is used pharmaceutically as a binder, emulsifying agent, and suspending or viscosity enhancer.