Pharmacognosy | Lipids

Lipids

Fixed oils, fats, and waxes; esters or long-chain fatty acids and alcohols

Basic unit of lipid

Triglyceride

Components needed to form the basic unit of lipids

Three fatty acids and one glycerol

Fixed oils — fatty acid type

Unsaturated

Fixed oils — alcohol

Glycerol

Fixed oils — physical state

Liquid at room temperature

Fats — fatty acid type

Saturated

Fats — alcohol

Glycerol

Fats — physical state

Solid at room temperature

Waxes — acids

High-MW, straight-chain acids

Waxes — alcohols

High-MW, straight-chain alcohols

Waxes — physical state

Usually solid

Fixed oils — usual source

Plant sources

Fixed oils — exception to being liquid at room temperature

Cocoa butter (Theobroma cacao)

Why is cocoa butter used as a suppository base?

Cocoa butter is the exception to fixed oils being liquid at room temperature.

Fats — usual source

Animal sources

Fats — exception to being solid at room temperature

Cod liver oil

Waxes — usual physical state

Usually solid preparations

Jojoba oil

The only liquid plant wax

Acid value / acid number

Number of mg KOH needed to neutralize the free acids in 1 g sample

Ester value

Number of mg KOH needed to saponify the esters in 1 g sample

Saponification value / Koettsdorfer number

Acid value + Ester value

Saponification value

Number of mg KOH needed to neutralize the free acids and saponify the esters in 1 g sample

Iodine number

Measures degree of unsaturation

Iodine number — what does it measure in fats or oils?

How many double bonds are in the fat or oil sample

Double bonds as sites for reactions

Hydrogenation, oxidation, and iodination

Ability to absorb oxygen and form a dry film

Related to iodine number

Non-drying oils — iodine number

Examples of non-drying oils

Peanut, almond, coconut, olive (PACO)

Semi-drying oils — iodine number

Between 100 and 120

Examples of semi-drying oils

Cottonseed, sesame

Drying oils — iodine number

120

Examples of drying oils

Soybean, linseed

Soybean oil

Most nutritious fixed oil; used in Intralipid TPN

Linseed oil

Used in painting

Effect of oxygen on double bonds

Oxygen saturates double bonds to form oxides that may polymerize.

Oxidized oils that polymerize

Form a hard film used in paint

Hydrogen binding in a double bond

Prevents rancidification

Oxygen binding in a double bond

Causes peroxidation, which causes rancidification

Burned fat

Acrolein

Three classes of active ingredients of medicinal plants

Terpenes, aromatic compounds, alkaloids

Seven categories of active ingredients

Phenylpropanoids, quinones, flavonoids, tannin, terpenes, sterols and their glycosides, alkaloids

Phenylpropanoids

C6-C3-C6; aromatic volatile oils; coumarin

Quinones

Anthraquinone

Flavonoids

Non-hydrolysable tannin

Tannin

Hydrolysable tannin

Terpenes

From triterpenes

Acetate-mevalonate pathway products

Fatty acids, phenolic compounds, terpenoids

Cinnamic acid pathway products

Phenylpropanoids, coumarin, lignin, flavonoids

Amino acid pathway product

Alkaloid

Combined pathways

For more complex products

Summary of pathways

Interrelationship of the different pathways

Pathways involved in the summary

Calvin Cycle (photosynthesis), glycolysis, shikimic acid pathway

Shikimic acid pathway

Amino acid pathway → alkaloid

Acetyl-CoA + Malonyl

Fatty acids

Acetyl-CoA + glycerol

Fixed oils, fats

Acetyl-CoA + fatty acid + alcohol

Fixed oils, fats, waxes

Acetyl-CoA products

Plant acids such as citrate, isocitrate, maleate, fumarate, etc.

Acetyl-CoA can also enter

Acetate-mevalonate pathway

Deoxy-D-xylulose

Precursor of Vitamin B1 (thiamine) and Vitamin B6 (pyridoxal)

Three acetyl-CoA molecules

Converted to HMG-CoA through HMG-CoA reductase

HMG-CoA reductase

Inhibited by statins

HMG-CoA gives rise to

Mevalonate

Mevalonate pathway product

Isopentenyl pyrophosphate (IPP)

IPP

Isomer of dimethylallyl pyrophosphate (DMAPP)

IPP and DMAPP molecular formula

C5H8

DMAPP + IPP

Geranyl pyrophosphate (GPP), C10 monoterpene

GPP + IPP

Farnesyl pyrophosphate (FPP), C15 sesquiterpene

Monoterpenes and sesquiterpenes

Lead to acyclic/cyclic non-aromatic volatile oils

Aromatic volatile oils

From phenylpropanoid under prephenic and cinnamic acid

FPP × 2

Sterols

Sterols lead to

Cholesterol, ergosterols, and all steroidal compounds

Steroidal compounds include

Hormones and fat-soluble vitamins

2× FPP also leads to

Triterpenes

Triterpenes

Another source of non-aromatic volatile oils; can be cyclic or acyclic

Polyterpenes

Rubber and gutta-percha

DMAPP can be used in

Mitochondria

Mitochondria

Powerhouse of the cell

ATP production in mitochondria

Electron Transport Chain (ETC), also called oxidative phosphorylation

Last receiver of electrons in ETC

Oxygen

Final product of ETC

Water

Electron carrier Q-9 + Q-10

Ubiquinone

Ubiquinone use mentioned

Antioxidant in cosmetics

Ubiquinone in ETC

Is oxidized instead of the cells

Only non-protein electron carrier in ETC

Ubiquinone

Why is ubiquinone non-protein?

It is a terpenoid produced in the acetate-mevalonate pathway.

Pathway inhibited for cholesterol lowering

Acetate-mevalonate pathway

Plastid substrates

Glyceraldehyde-3-phosphate (GA-3P) and pyruvate

GA-3P and pyruvate in plastid

Converted to deoxy-D-xylulose (pentulose)

Deoxy-D-xylulose

Precursor of Vitamin B1 and B6

DMAPP + IPP in plastid

GPP

GPP + 2 IPP

Geranylgeranyl pyrophosphate (GGPP), C20 diterpene/phytol

GGPP

C20 diterpene/phytol

Difference between hemoglobin and chlorophyll

Hemoglobin has an iron ring; chlorophyll has a porphyrin ring with magnesium in it.

Chlorophyll porphyrin ring

Contains magnesium and a phytol tail

GGPP × 2

Carotenoids (C40), an orange pigment

Carotenoids when oxidized

Xanthophyll, a brown pigment

GGPP + 5 IPP

Plastoquinones

Plastoquinones

Involved in absorption of UV light and photosynthesis

Triglyceride

Main unit of fatty acids