Lipids and Prostaglandins Flashcards

Flashcards covering key vocabulary and concepts related to lipids, fats, oils, waxes, and prostaglandins, including their structures, properties, and physiological roles.

Lipids Esters

Arise from the union of an alcohol and an acid with loss of water; the reaction is reversible and in plants esterase enzymes control the reaction.

Simple Lipids

Fixed oils, fats, and waxes

Complex Lipids

Phosphatides and lecithins which may contain phosphorus and nitrogen in addition to carbon, hydrogen, and oxygen.

Lecithins

Esters of glycerophosphoric acid in which two free hydroxyls of the glycerol are esterified with fatty acids while one of the two remaining groups of the phosphoric acid is esterified to an alcohol (choline, ethanolamine, serine, glycerol, or inositol).

Triglycerides (Triacylglycerols)

Simple lipids in which all three hydroxyl groups are esterified with fatty acids.

Fixed Oils

Oils obtained from fruit pericarps, and in some instances, two oils differing in properties and chemical composition are obtained (e.g., palm kernel oil and palm oil from Elaeis guineensis).

Acylglycerols

Can be hydrolyzed by heating with caustic alkali to form soaps and glycerin.

Simple Triacylglycerol

A triacylglycerol in which the fatty acids represented by R1, R2, and R3 are the same; hydrolysis yields three molecules of the same fatty acid (e.g., tripalmitin yields palmatic acid).

Mixed Triacylglycerol

A triacylglycerol in which R1, R2, and R3 are usually different; hydrolysis frequently yields both saturated and unsaturated acids.

Acid Value

The number of mg of KOH required to neutralize the free acids in 1 g of the oil. High values indicate rancidified oils, while low values are specified for parenteral dosage forms.

Saponification Value

The number of mg of KOH required to neutralize the free acids in, and to hydrolyze the esters in, 1 g of the substance.

Ester Value

The difference between the saponification and acid values.

Iodine Value

A measure of the unsaturation of the oil. High iodine values indicate oils which partially resinify on exposure to air (semidrying or drying oils).

Volatile Acidity

Useful for determining lower fatty acids (e.g., butyric acid) that are volatile in steam and can be separated and estimated.

Unsaponifiable Matter

Compounds such as sterols which remain after saponification of the acylglycerols and removal of glycerol and soaps by solvents.

Acetyl Value

The number of mg of KOH required to neutralize the acetic acid freed by the hydrolysis of the acetylated fat or other substance.

Hydroxyl Value

A measure of the number of free hydroxyl groups present, expressed as the number of mg of KOH required to neutralize the acid combined by acylation of the sample.

Peroxide Value

The number that expresses in milliequivalents of oxygen the quantity of peroxide contained in 1000 g of the substance. Detects deterioration under unsuitable storage conditions.

Anisidine Value

Determined photometrically (350 nm) and depends on the colored complex produced by the interaction of p-anisidine with aldehydes and ketones; used principally for fish oils.

Waxes

Natural mixtures containing appreciable quantities of esters derived from higher monohydric alcohols of the methyl alcohol series combined with fatty acids.

Prostaglandins (PGs)

Bioactive lipid compounds derived from arachidonic acid, a 20-carbon unsaturated fatty acid; a type of eicosanoid.

COX-1

Constitutive cyclooxygenase isoform involved in normal physiological functions.

COX-2

Inducible cyclooxygenase isoform expressed primarily in inflammation.

PGE₂

Prostaglandin that mediates inflammation, pain, and fever, and protects gastric mucosa by inhibiting acid secretion and stimulating mucus and bicarbonate production.

PGF₂α

Prostaglandin that induces uterine contractions and is used clinically to induce labor or abortions.

PGI₂ (Prostacyclin)

Prostaglandin that causes vasodilation and inhibits platelet aggregation.

TXA₂ (Thromboxane A₂)

Prostaglandin that causes vasoconstriction and promotes platelet aggregation.

Misoprostol

Synthetic PGE₁ analog used to prevent NSAID-induced ulcers and induce labor or abortion.

Dinoprostone (PGE₂)

Used for cervical ripening and labor induction.

Latanoprost (PGF₂α analog)

Used in glaucoma to reduce intraocular pressure.