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Pharmacognosy & Pharmaceutical Biology > Lipids > Flashcards

Lipids Flashcards

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1
Q

what are lipids (3)

A
  • organic polar, hydrophobic compunds
  • esters of fatty acids and an alcohol
  • simple or complex types
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2
Q

simple lipids include (3)

A
  • glycerol fixed oils (fats)
  • long chain monohydric waxes
  • sterol based waxes
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3
Q

complex lipids are associated with these organs (5)

A
  1. heart muscle
  2. myelin sheath
  3. brain tissue
  4. cell membranes
  5. skin
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4
Q

complex lipids are classified as (3)

A
  1. phosphoglycerides
  2. glycolipids
  3. sphingolipids
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5
Q

the majority of pharmaceutically important lipds are simple or complex?

A

simple

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6
Q

fixed oils/fats differ from alkaloids, glycosides, and terpenes as they are

A

primary metabolites

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7
Q

why are fats necessary (3)

A
  • great nutritional value
  • concentrated reserve of energy
  • dietary source of essential fatty acids which are precursors for prostaglandins
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8
Q

sources of fixed oils (2)/fats(1) include

A

Fixed Oils

  • oil seeds
  • animal sources
    • cod
    • halibut
    • shark

Fats

  • animals
    • pig (lard)
    • beef (tallow)
    • sheep (suet)
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9
Q

isolation of oils from vegetable sources includes these 2 processes

A
  • hot and cold expression
  • cold expression yields purer oils e.g. virgin olive oil
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10
Q

hot expression process involves

A
  • screening of seeds to remove debris
  • magenet removes iron
  • pass through steel rollers, cook meal 70-100C to rupture cells
  • force through archimedian screw press
    • high pressure yields low quality oil but higher extraction yield
    • low pressure higher quality oil, less yield
  • seed cake from low pressure can be further extracted using solvent extraction
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11
Q

which oils require further refinement

A

hot pressed

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12
Q

which type of extraction low or high pressure are used in pharma

A

low pressure because purer

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13
Q

oils/fats from animal sources are isolated by

A

wet rendering

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14
Q

describe the wet rendering process

A
  • chunks of animal material into SS tank
  • jacketed cyclinders in tank release steam under pressure through biomass
  • oil cells break open, liquid/fat floats to surface, water/waste settles below
  • draw off supernatant periodically
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15
Q

why is it important that fresh livers free of gall bladder are used for cod liver oil

A

because lipases in old livers would cause decomposition of the oils

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16
Q

why is refinement of hot pressed oils required to remove (7)

A
  1. free fatty acids
  2. reduce triglycerides
  3. remove pigments,
  4. oxidation products
  5. waxes,
  6. odors
  7. proteins
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17
Q

what are 4 methods of refinement

A
  1. neutralization with alkali
    • removes free fatty acids
  2. bleaching
    • removes pigments
  3. deoderizing
    • remove odors
  4. winterizing
    • chilling to 0C to remove solid fats or waxes
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18
Q

true fats are_________at normal room temp, while fats are _________at room temp

A
  • liquid
    • also known as fixed oils
  • solid or semi-solid
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19
Q

all fats and fixed oils are chemically classified as ________and when combined with varying amounts of glycerol are known as_______

A
  • glycerides of fatty acids
  • monoglycerides, diglycerides or triglycerides
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20
Q

what is the major constituent of undecomposed true fats

A

triglycerides

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21
Q

for triglycerides when the three functional groups are the same they are considered simple or complex lipids, is this common?

A
  • simple
  • no most are mixed triglycerides
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22
Q

triglycerides of short chained saturated or unsaturated fatty acids are liquid or solid at room temp and predominate in fixed oils or fats

A

triglycerides of short chained saturated or unsaturated fatty acids are liquid at room temp and predominate in fixed oils

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23
Q

triglycerides of long chained fatty acids are liquid or solid at room temp and predominate in fixed oils or fats

A

triglycerides of long chained fatty acids are solid at room temp and predominate in fats

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24
Q

what is the controlling factor of triglyceride levels in plants and animals

A
  • Plants - temperature
  • Animals - diet
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25
Q

fatty acids that are common in plants and animals contain (4)

A
  • even number of carbons
  • straight chain
  • terminal COOH
  • fully saturated or up to 6 dble bonds
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26
Q

saturated fatty acids

A

have no double bonds

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27
Q

unsaturated fatty acids

A
  • have varying degrees of double bonds up to 6
  • generally cis configuration
  • those in trans may be damaging to biological system
28
Q

saturated fatty acids contain this at the end of the name

A

“OIC”

29
Q

naming convention includes these two elements

A
  • trivial name
    • source
  • systematic name
    • number of saturated hydrocarbons with same number of carbon atoms
30
Q

what does the shorthand designation relate to for saturated fatty acids e.g. 4:0

A
  • number of carbon atoms: number of double bonds
31
Q

the systematic naming convention for unstaturated fatty acids includes adding the following endings before the terminal “oic”. what do these relate to

A
  • en
  • dien
  • trien
  • number of double bonds
32
Q

what are the pharmaceutical uses of fixed oils and fats (6)

A
  1. nutritive/dietary supplement - Almond, cod liver, coconut
  2. emollient - almond, olive
  3. solvent for injections - sesame, almond
  4. purgative - castor oil
  5. ointment base - coconut
  6. suppository base - theobroma oil
33
Q

why are polyunsaturated fatty acids (liquid fixed oils) included in the diet, and what are they are treatment for?

A
  • rich source of linoleic, linolenic and arahidonic essential fatty acids
    • precursors for prostaglandins
  • treatment of coronary heart disease, high cholesterol, atherosclerosis
34
Q

what are two differences between fixed oils and volatile oils

A
  • cannot be distilled without decomposition
    • volatile oils predominantly separated using distillation
  • leave a permanent greasy stain on paper
    • volatile oils evaporate
35
Q

what are general properties of fixed oils/fats (5)

A
  1. can’t be distilled without decomposition
  2. leave permanent greasy stain on paper
  3. insoluble in water, but soluble in most organic solvents except alcohol
  4. relative density <1
  5. sticky and greasy to touch
36
Q

what are 3 challenges with the standardization of fixed oils and fats

A
  • wide natural variation
  • expesive oils susceptible to adulteration with cheaper oils
  • estimation of single constituent does not indicate quality or purity
37
Q

what should standardization of fixed oils focus on (4)

A
  1. physical measurements
    • melting point
    • relative density
    • refractive index
    • solubility
  2. qualitative or limit tests for oils likely to be used as adulterants
  3. chemical constants
    • acid, iodine values
  4. chromatography
    • TLC, GC
38
Q

what is acid value a measure of

A
  • the amount of free fatty acids present in the oil
  • indicative of whether hydrolysis or decompostion of the oil has occurred
39
Q

what is iodine value a measure of

A
  • indication of amount of unsaturation where drying oils have large iodine values
  • classifies the oil as a
    • wax
    • solid fat
    • non-drying oil - mainly monounsat
    • semi-drying oil - mixture
    • drying oil - mainly polyunsat
40
Q

what is the saponification value a measure of

A
  • differentiates true fats (fatty acid esters of glycerol) from waxes (fatty acid esters of monhydric alcohols)
  • true fats have high saponification values
41
Q

hydroxyl value is a measure of

A

the number of OH groups in the sample

42
Q

peroxide value is indicative of

A
  • oxidation or rancidity
  • a high peroxide value indicates degradation by oxidative processes has occurred
43
Q

unsaponifiable matter is a measure of

A
  • the extent of non-glyceride matter
  • indicative of adulteration
  • high value indicates adulteration
44
Q

commercially processed true fats consist of 99.5% triglycerides, the remaining 0.5% is made up of these 5 things

A
  1. sterols (cholesterol)
  2. unsaturated hydrocarbons
  3. complex lipids
  4. pigments
  5. oil soluble vitamins
45
Q

decomposition of oils occurs by these 3 primary reactions

A
  1. hydrolysis
  2. methyl ketones
  3. oxidation
46
Q

hydrolysis of oils occurs as a result of __3 things__and produces this_____. this can be prevented by

A
  • moisture, bacteria or lipases
  • free fatty acids
    • undesirable odors or taste
  • prevent by keeping moisture below 0.01%
47
Q

formed when fungi convert free fatty acids or triglycerides to this

A

methyl ketones

48
Q

methyl ketones will impac the oil by

how can methyl ketone formation be prevented

A
  • changing flavour or taste making offensive
  • not using cork which could be source of fungi, keeping moisture level low, and storing in cool temp
49
Q

which oil/fat types are most susceptible to oxidative decomposition

A
  • semi-drying and drying oils
  • because of the greater degree of unsaturation in the fatty acids makes the molecule more unstable
50
Q

what is autoxidation

A
  • is spontaneous oxidation which occurs at room temp in the pesence of light and air
51
Q

hydrogen peroxidases are responsbile for the development of off flavours which on decomposition produce objectionable compounds such as

A

aldehydes

52
Q

oxidative changes in simple fats/oils include these two things

A
  • oxidative rancidity
  • flavour reversion
53
Q

oxidative rancidity of fats/oils is caused by

A
  • autoxidation of all unstaturated fatty acids
54
Q

flavour reversion is the result of autoxidation of this and mainly affects these oils

A
  • unsaturated fatty acids with 3 or more double bonds
  • semi-drying or drying oils only
55
Q

autoxidative decomposition of fats/oils can be prevented by

A
  • storing in air tight container, no light, cool temperature, adding antioxidants
  • minimization of air maintained by filling the container full
56
Q

antioxidants used in preservation of fixed oils/fats fall into 3 categories. which are commonly used with lipids

A
  • reducing agents*
  • antioxidant synergists*
  • true or primary antioxidants
57
Q

antioxidant synergists

A
  • chelating agents
  • enhance the action of primary or true antioxidants by reactinv with heavy metal ions which catalyze in stage 1 of autoxidation
  • e.g. citric acid, lecithin, tartaric acid
58
Q

what are some challenges with the use of antioxidant synergists (2)

A
  • they need to be added early in the extraction process
  • can increase acid values if used at too high a level
59
Q

true or primary antioxidants inhibit oxidation by

A
  • reacting with free radicals blocking the chain reaction in catalytic autoxidation
  • e.g. tocopherol (vitamin E), BHA and BHT (butylated hydroxyanisole/butylated hydroxytoluene)
60
Q

waxes are materials which are

A

solid, non-greasy and melt at low temp

e.g. carbowax

61
Q

these waxes are esters of HMW monohydric alcohols and HMW straight chain fatty acids

A

true waxes

62
Q

what are sources of wax and uses

A

animals and plants

  • carnuba wax - leaves of wax palm
    • tablet polishing
  • beeswax - honeycomb
    • ointments
  • woolfat - anyhydrous lanolin from sheep wool
    • emollient creams
  • wool alcohols - alcoholic fraction of wool fat
    • ointments
63
Q

how are waxes obtained

A

typically mechanical dislodgement followed by solvent extraction

64
Q

natural waxes are made up of complex mixtures of (3)

A
  • fatty acids and fatty alcohols
  • as free or combined esters
  • generally < C16
65
Q

properties of waxes that distinguish them from true fats (5)

A
  1. difficult to saponify
  2. low saponification values
  3. low idodine values
  4. higher acid values
  5. higher unsaponifiable matter
66
Q

how are waxes standardized (10)

A
  1. acid value
  2. iodine value
  3. saponification value
  4. selective solubility
  5. melting point
  6. ester value
  7. ratio number
  8. sulfated ash
  9. acid/alkaline substances
  10. weight of parrafins

Pharmacognosy & Pharmaceutical Biology (14 decks)

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