Phytochemistry, Lipids

Phytochemistry, Lipids

Clinical Pharmacy, Phytochemistry Section

A study in Phytochemistry which is the chemistry of plants ingredients as a revision for professionals & students

Done By Ismail Mortada

B.Sc.Pharmacy & Health Sciences, Clinical Pharmacy Section

هذه مقالة سريعة جدا تعنى بدراسة التكوين الكيميائي للدهون النباتية, وهي غير شاملة ولكنها مقتطف سريع جدا حيث ان هذه المقالة تتبع قسم (كيمياء النبات) والذي لا يفصل كثيرا في بعض الأمور, وسادرج مقالات أخرى أكثر توسعا حول الموضوع عندما نتناوله من جانب الكيمياء العضوية حيث أنه يكون متشعبا أكثر وأكثر أهمية, اما كيمياء النبات فهي تعنى بأمور تخصصية معينة في تركيبة المواد الكيمياء الطبيعية المختلفة

دراسة ومراجعة اسماعيل المرتض

يمكن التزويد بالمراجع المستخدمة عند الطلب

Lipids are substances of biological origin that dissolve in many organic non-polar solvents, But are insoluble or very slightly soluble in water. Lipids are usually compounds of Fatty Acids or complex alcohols esters or even having different structure. Their major function s to store food energy, Fatty acids are mono-carboxylic Acids, usually having 21 to 22 carbons with one or more double bonds, Lipids generally includes the following

A) Simple Lipids, such as Fixed oils, Fats & Waxes
B) Complex Lipids such as phophotides & Lecithins which contain phosphorous & nitrogen in addition to carbon, hydrogen & oxygen

FIXED OILS, FATS & WAXES

Fixed oils & fats are esters of long chain fatty acids with a tri-hydric alcohol (glycerol), Usually the glycerides of un-saturated fatty acids are liquid. whereas the glycerides of saturated fatty acids of sufficient chain length are solids, check the following pictures to have a more clear understanding about the structure of fatty acids & glycerides esters

Fixed oils & fats are naturally occuring mixtures of lipids widely distributed in both animals & plants. The word “Fixed Oils” & “Fats” are interchangable according to the lipid being solid or liquid at room temperature

Most lipids from vegetable origin are liquids (cottonseed oil) with few exceptions like (theobroma oil = cocoa butter), While lipids from animal origin are semi-solids or solids (like lard) with the exception of cod liver oil

Oils & Fats of vegetable origin are obtained by expression or by solvent extraction, If expression is carried out in the cold, the oil is known as “Virgin Oil” or a “Cold Pressed Oil”, In contrast; if the process is carried out in heat, the oil is known as “Hot-Pressed Oil”, Animal fats are separated from other tissues by rendering with steam, with or without pressure. The heat melts the fats, which rises to the top to be separated by decantation

Fixed oils are classified into drying, semi-drying & non-drying, a classification based on their ability to absorb oxygen from the air

There are several pharmacopeial tests based upon chemical constitution of fatty acids, These tests are used to determine the identity, quality & purity of fixed oils, USP recommends the acid value (acid number ), saponification value, iodine number & Reichert-Meissl number

A) The Acid Value: It is a number of mg of KOH required to neutralize the free fatty acids in 1g of the substance, for example the acid value of Castor Oil must not exceed 2
B) The Saponification Number: It is the number of mg KOH required to neutralize the free fatty acids resulting from the complete hydrolysis of 1g of the substance
C) The Iodine Number: It is the number of g of Iodine, absorbed by, under prescribed conditions, by 100g of the substance
D) Reichert-Leissl Number: It is the number of ml. of 0.1N KOH required to neutralize the volatile water soluble acids obtained by the hydrolysis of 5g of the fat

Waxes are esters of fatty acids & large mono-hydroxy alcohols (chain or cyclic) of high molecular weight such as for example cetyl alcohol

CH3(CH2)14CH2OH

Waxes are found in diversity of places, such as the surface of leaves of many plants, furs of animals & the secretions of insects (like beeswax), Waxes also contains appreciable quantities of free fatty acids, hydrocarbons, free alcohols & sterols. It is thus noted that acid values of waxes are higher than those of fats & oils

OLIVE OIL

It is the fixed oil obtained from the ripe fruits of Olea europaea of the family Oleaceae. The tree was apparently a native of palestine & has been widely cultivated in the Mediterranean countries

Olive oil is pale yellow or light greenish yellow with a characteristic odour & a faint acrid taste

The chemical composition of olive oil seems to vary rather widely, 2 major types are recognized based upon the relative concentrations of the component acids of the glycerides. The turkish variety contains about 75% Oleic Acid, 10% of Palmitic Acid, 9% of Linoleic Acid & lesser amounts of other acids, The Italian variety contains only about 65% of Oleic Acid, 15% of each Palmitic & Linoleic Acids, & other minor acids

Olive oil is classed as a pharmaceutical aid, in the preparation of soaps, plasters & liniments. It is also demulcent, an emollient & a laxative, Olive oil is a nutrient & is widely used as salad oil

So olive oil is made up in general of Glycerol + Fatty acids like oleic, palmitic & linoleic acids

COD LIVER OIL

It is the partially de-stearinated fixed oil obtained from the fresh livers of Gadus morrhua & other species of the family Gadidae

The fresh livers are steamed in close heat exchangers & the oil that rises to the top is collected, The air above the oil is replaced by CO2 to prevent oxidation. The oil is then strained, decanted & cooled to a temperature below 5 degree centegrate, During this process stearin seperates out as a solid & the lighter oil is decanted & filtered. The liver marc (liver remianing) is often re-steamed for a further yield of oil that is used for technical purposes, note that stearin is partially removed from fixed oil & it is an ester of stearic acid & note that for stearing & decantation we use a bandage & not filter paper

Note that in decantation, it contains the liquid + a substance, so need for filtration, just pouring the liquid is enough to separate them from each other

Cod liver oil is a pale yellow liquid with a slight fishy odour & taste, It is slightly soluble in alcohol but freely soluble in ether, chloroform & ethyl acetate

The medicinal constituents are vitamin A, Vitamin D + Saturated & Un-Saturated fatty acids, The oil contains glyceryl esters of those fatty acids

Cod liver oil is employed for its contents of anti-xerophthalmic & anti-rachitic vitamins which is used for vitamin D weakness & its symptoms in the human body

WHITE BEESWAX, Cerba alba
YELLOW BEESWAX, Cerba flava

Yellow beeswax is obtained by melting & purifying the honey comb of the bee Apis mellifera, family Apidae

The honey comb, after separation from the honey, is melted in water, then cooled & remelted & finally strained & allowed to harden in molds, so the honey is melted in water & then the wax is separated for several times
It is a solid varying in colour from yellow to grayish brown, It has an agreeable honey like odour & faint taste. It is insoluble in water, partially soluble in 90% ethanol & completely soluble in volatile & fixed oils

The wax consists prinicpally of alkyl esters of fatty & wax acids (chiefly myricyl palmitate), free wax acids, hydrocarbons & minor constituents

Yellow wax is a stiffening agent & is an ingredient in yellow ointment & as a base for plasters, It is contained in a number of polishes

White wax is bleached, purified wax & is also knwon as bleached beeswax, It is employed pharmaceutically in ointment & in cold creams

Phytochemistry, Lipids

Clinical Pharmacy, Phytochemistry Section

A study in Phytochemistry which is the chemistry of plants ingredients as a revision for professionals & students

Done By Ismail Mortada

B.Sc.Pharmacy & Health Sciences, Clinical Pharmacy Section

Tags: fatty acids, fixed oils, Phytochemistry