PCOG: Lipids

Lipids

• Also known as lipin or lipoids. These are fat & fat-like substances which occur in plants and animals

• They all contain Carbon, Hydrogen, and Oxygen

• Some also have Phosphorus and Nitrogen

• More heterogenous in its composition, since it is composed of esters of long-chain fatty acids and alcohols

Fixed Oil or Fatty Oil

Are liquid at normal temperature

Fats

Are semisolid or solid at ordinary temperature

Occurrence of Lipids

Vegetable oils and fats may occur in various part of the plant but as a general rule seeds contain larger quantities of fats and oils

Methods of Obtaining Lipids | Expression in Hydraulic Process

Carried out in the cold

• Products are Virgin Oil or Cold-Pressed Oils in contrast to a Hot-Pressed Oil in which heats is used.

Methods of Obtaining Lipids | Filtration and Ozone-Bleaching

The preferred method of purification

Composition of Oils

These oils are constructed from 2 kinds of compounds

• Glycerol: a 3 carbon alcohol

• Fatty Acid: Indicated by the prefix acyl

Classification of Fatty Acid | Saturated

Fatty acids with only single bonds

Classification of Fatty Acid | Monosaturated

It has one double bond

Classification of Fatty Acid | Polyunsaturated

More than one double bond

Simple Lipids

Esters of Fatty Acids and Alcohols

• Fats & Fixed Oils → Esters of Fatty Acids and Glycerols

  • Ex: Olive Oil, Lard

• Waxes → Esters of High MW, Monohydric alcohol and High MW Fatty Acid

  • Ex: Spermaceti

Compound Lipids

Esters of fatty acids and alcohols in combination with other compounds

• Phospholipids

• Glycolipids

Vegetable Oils

• They are glycerides mostly in the vegetable kingdom

• Classified according to their Drying Properties (Based on the ability to absorb oxygen from the air)

Drying Oil

• Oils with many double bonds tend to link together forming polymers

• Contain many linoleic and linoleic acids

• Iodine Value >150

• Ex:

  • Linseed Oil, Tung Oil, Poppyseed Oil, Hempseed Oil, Walnut Oil, Sunflower Oil

Semi-Drying Oils

• Contain many oleic and linoleic acids

• Iodine Value: 100 - 150

• Ex:

  • Corn Oil, Cottonseed Oil, Wheat Oil, Sesame Oil, Brazil Nut Oil, Soybean Oil, Rape Seed Oil

Non-Drying Oils

• Contain large quantities of oleic acid

• Iodine Value: 70 - 100

• Ex:

  • Rice Oil, Palm Oil, Coconut Oil, Olive Oil, Peanut Oil, Date Oil

Hydrolysis of Fats and Oils

• Hydrolysis of fats yield glycerol and fatty acids

• Most fats and oils with age, develop a bad odor and taste, leading to rancidity

Types of Rancidity | Oxidative Rancidity

Caused by the oxidation of unsaturated fatty acids at their double bonds, with the production of shorter-chained acids, aldehydes and ketones. This is corrected by the used of antioxidants

Types of Rancidity | Hydrolytic Rancidity

The bad odor and taste are due to the free fatty acids liberated, when that fat is hydrolyzed

Commonly Used Antioxidants | Aqueous System

Sodium Sulfite, Sodium Metabi-Sulfite, Sodium bisulfite, Sodium Thiosulfite, and Ascorbic Acid

Commonly Used Antioxidants | Oil Systems

Ascorbyl palmitate, Hydroquinous, Propyl Gallate, Nordihydroguaia-retic Acid, Butylated Hydroxytoluene, Butylated Hydroxyanisole and Alpha Tocopherol

Peanut Oil &Sesame Oil

Solvents for IM Injectables

Castor Oil

Cathartic

COD Liver Oil

Emollient

Chaulmoogra Oil

Antileprotic

Linseed Oil

Protective, Demulcent, EmollientC

Cottonseed Oil

Solvent, Emollient in Liniment Preparation

Almond Oil

Emollient, Pharmaceutic Necessity

Persic (Avocado) Oil

Emollient, Pharmaceutic Necessity

Coconut Oil

Component of chocolate confectioneries & candies, Hairdressing Aid, Manufacture of Soaps, Candies, Ointment Bases

Corn Oil

Solvent for IM Injectables, Preparation of Food and Salad Dressing

Theobroma Oil

• Scientific Name: Theobroma cacao

• Family Name: Sterculiceae

• Constituents: Oleic 37%, Stearic 35%, Palmitic 16%, Linoleic 2%

• Uses: Suppository Base

Lanolin

• Scientific Name: Ovis aries

• Family Name: Bovidae

• Constituents: Cholesterol, Isocholesterol, and Esters of Lanopalmitic, Lanoceric, Carnaubic, Oleic, and Myristic

• Uses: Water absorbable ointment base

Spermaceti

• Waxy substance obtained from the head of sperm whale

• Scientific Name: Physeter macrocephalus

• Family Name: Physeteridae

• Uses: Pharmaceutic aid for cold cream and emollients

Lecithin

• When completely hydrolyzed, each molecules of lecithin yields 2 molecules of fatty acids, and 1 molecule of Glycerol & Phosphoric Acid & Choline (a basic nitogenous compound)

• Fatty acids obtained from lecithin, upon hydrolysis are: Oleic, Palmitic, and Stearic Acids

• Obtained from the extraction of eggyolk (ovolecithin), brain tissue of soya beans (vegilecithin)

Cephaline

• Associated with the process of blood clotting, are closely related to lecithin in the structure.

• An essential constituent of various body tissues

  • It differs from lecithin, in that choline is replaced by cholamine, serine, or meso-inositol (as the basic, nitrogenous product of hydrolysis)

Spingomyelins

Completely hydrolyzed, it yields fatty acids, phosphoric acid, choline and spingosine (secondary basic, nitrogenous substance)

Glycolipids

• Substances isolated from the brain & various other sources.

• Upon hydrolysis yields fatty acids, galactose, and spingosine

• Ex:

  • Phrenosin & Kerasin

• Sometimes referred to as galactose (due to its sugar moiety)

• At present glycolipids have no pharmaceutical application

Derived Lipids in Plants

• Repellant to insects, thus preventing the destruction of the flowers and leaves

• Serve as insect attractants, thus aiding in cross-fertilization of the flowers.

Flavorant

Lemon Oil

Perfume

Rose Oil

Turpentine Oil

Starting material for the synthesis of other compoundsI

Inhalation Compounds

Eucalyptus Oil

Carminative Oil

Peppermint Oil

Mouthwash/Gargle

Thyme Oil

Aromatherapy

Lavender, Rosemary, Bergamot Oil

Antiseptic

Clove Oil & Thyme Oil

Antispasmodic

Rosemary, Peppermint, orang Oil

Characteristics of Voltaile Oil

• They posses characteristics odor such as sweet, pungent, hot acrid, caustic or with burning taste

• They are characterized by high refractive indeces

• Most of them are optically active

Differences of Volatile Oil from Fixed Oil

• Capable of volatilization

• Can be distilled from their natural sources

• Do not consist of glyceryl esters of fatty acids

• Do not leave a permanent spot on paper

• Cannot be saponified with alkalies

• Do not become rancid but instead upon exposure to light and air, they oxidize and resinify

Volatile Oil Consists

• Eleophene: The liquid portion of the oil composed of hydrocarbons.

• Stearoptenes: The oxidized hydrocarbon portion of the oil are usually solid

Enzymatic Hydrolysis

By using emulsin & myrosin

Enfleurage

• The flower petals are placed on the fat for a few hours, then a new layer of petals is introduced. After the fat has absorbed as much fragrance as possible, the oil may be removed from it by extraction with alcohol

• Used in the production of perfumes and pomades

Extraction

• Modern essential oil production is accomplished by extraction, using solvent systems based on volatile solvents such as petroleum ether or benzene

• Advantage of Extraction over Distillation

  • Uniform Temperatures: 50^oC can be maintained during the process.

  • Extracted oils have a more natural odor

Destructive Distillation

• A means of obtaining empyreumatic oils

• When the wood or resin of members of the Pinaceae is heated without access of air, a decomposition takes place, and a number of volatile compounds are driven off

Oil Lighter than Water are Usually Rich In

• Hydrocarbons

• Alcohols

• Esters

• Ketone

Oils Heavier than Water are Usually Contain Chiefly of

• Aldehydes

• Phenols

• Phenolic Derivatives

• Esters

Specific Gravity

• Maybe determined with a Westphal Balance and Pycnometer

• Pycnometer

  • The official method and the more accurate of the two

• The ratio between the weight of the volume of oil to that of an equal volume of pure water at 25^oC

• For official Volatile Oil range between 0.84 and 1.2

• Example of Oil Lighter then Water:

  • Orange, Caraway, Coriander, Lemon, Turpentine, and Rosemary Oil

• Example of Oil Heavier than Water:

  • Anise, Cinnamon, Clove, and Sassafras Oil

Rotatory Power

• Measured with a Laurent half-shadow polarimeter

• Observation of the optical activity of volatile oil should be made at 25^oC

• This serves as a means of detecting adulteration with inactive substances such as alcohol or with substances of rotatory power different from that of the oil being measured

• Ex:

  • Lemon Oil (+57 to 65.6 deg.) Adulterated with Turpentine Oil (+25 to -40 deg)

Refractive Index

• Determined by mean of an Abbe Refractometer

• Th measurement is performed at 20^oC except rose oil which is measured at 30^oC

• The value being between 1.46 and 1.61 at 20^oC