Solvents Flashcards
To understand all the various solvents used in making herbal preperations
Name the 7 different solvents or “menstrua” used in herbal preparations
Alcohol, water, alcohol-water mixture, vinegar, wine, glycerine, and oil
What are the concerns related to the use of wine and vinegar as menstruums?
wine and vinegar contain other plant material and sometimes yeast that tends to change the chemical composition and therefore the qualities of the herbal extract in unpredictable ways.
This is particularly important when issues such as predictability, permanence, and control are important such as when considering the potency and toxicity of some herbs.
When is vinegar and wine contraindicated?
for use with very strong or toxic herbs that are dose specific. Or for the long term preservation of an extract
Which constituents are best extracted with cold water?
Cold water is a good solvent for plant constituents, such as sugars, proteins, albuminous bodies, gums, mucilaginous substances, pectin, tannins or plant astringents, plant acids, coloring matter, many mineral salts, many glycosides, some alkaloids, most all alkaloidal salts, and, to a slight degree, a hint of essential oils.
What are the advantages and disadvantages of using hot water as a menstruum?
Advantages:
- hot water allows for the more rapid extraction of plant material,
- it also swells and disintegrates the plant material, allowing for the extraction of starches and other constituents not readily soluble in cold water.
Disadvantages:
- hot water can destroy some chemical constituents.
- reduces shelf life as the heating process extracts material that separates out when the menstruum cools. either settling at the bottom or floating at the top as foam. This provides foods for organisms which reduces shelf and can potentially change the chemical composition. Which is why decoctions should be strained to remove the extraneous plant material in order to prolong its shelf life
What is the universal disadvantage of water as a menstruum?
It is not a preservative
during extraction, it also extracts enzymes (especially cold extraction) and it allows for the growth of molds, yeast, and bacteria, which alters the state of the extract
Water extractions only last up to two days
How can we preserve water extractions?
by freezing or adding a substance that prevents the multiplication of microorganisms and disables the enzymes, such as alcohol
Why is it that water often extracts water-insoluble constituents?
As plant matter becomes infused in water, it changes the solvent properties of water allowing water-insoluble constituents to dissolve in it
Which constituents dissolve in ethyl alcohol?
Ethyl alcohol is a good general solvent for extracting resins, balsams, camphors, essential oils, alkaloids and natural alkaloidal salts, glycosides, organic acids, chlorophyll, most coloring matter, nearly all the acrid and bitter constituents of a plant, un-crystallized, amorphous vegetable sugars, and one fixed oil: castor oil.
Which constituents do NOT dissolve in ethyl alcohol?
gums, mucilaginous substances, starch, albuminous materials, many mineral compounds, crystallized cane sugar.
Why is alcohol a good preservative?
alcohol paralyzes enzymes that are destructive to alkaloids and glycosides
prevents the growth of yeast, molds, other fungi, and most bacteria
prevents the breakdown of glycosides and sapponins due to water.
Which two solvents do alcohol mix well with?
Water and glycerin
What is meant by the negative strength of alchohol?
It means that alchohol is very selective in which constituents it will extract and which it will exclude.
We can use alchohol to exclude or expell certain constituents, like mucolage, albuminous matter, starch and gums, from an extract by adding a sufficient amount of alcohol to it
This is useful because, muculage, albuminous matter, starch and gums are often dificult to filter out of extracts and they tend to disturb solutions aswell as provide food for microbes which shortens the solutions shelf life.
How can we use alchohol to preserve an extract that contains alchohol insoluble components such as mucolage, without expelling it from the extract?
by adding only 18 to 20 percent alcohol.
What is the lowest volume of alcohol one can use to maintain its preservative function?
18 to 20 percent by volume
Which constituents are extracted by vinegar?
vinegar contains acetic acid which is a polar solvant and as such would extract most water soluble constituents.
Acetic acid is alos unparallelled at the extraction and fixing of alkaloids
When is vinegar the best menstruum to use?
When the activity of the medicine depends on specific alkaloids
alkaloids readilly binds with acetic acid to form alkaloidal salt that is soluble in water
What is vinegar?
vinegar is a dilute acetic acid derived from oxidized alchahol
Why did the pharmacists abandon vinegar as a menstruum?
because the amount of acetic acid in vinegar is variable and they needed a relaible way of producing dose specific medication from toxic plant.
What is glycerine?
The sweet fraction of a fixed oil, usually coconut oil.
What chemical family do glycerine belong to?
Chemically, glycerin belongs to the class of alcohol, and is termed glycerol or glyceric alcohol. However it is a tri-atomic alcohol and contains no ethyl alcohol or methyl alcohol which are di-atomic alcohols having dramatically different characteristics.
Glycerine has a sweet taste. Is it a sugar?
Glycerine is not a carbohydrate and contains no sugar and is absorbed and metabolized too slowly to effect blood sugar levels
Is glycerine safe for diabetics?
Yes
For who is glycerine particularly well suited?
For individuals who cannot tollerate alcohol and for children.
What kind of plant material is easier to extract with glycerine?
with plants that have relatively large amounts of ligneous (woody) fiber; water expands these gummy and/or glutinous materials far more than glycerin does
What is the name for an extract made with glycerine?
A glycerite
What is the relationship between glycerine, tannins, and alkaloids?
It reduces the precipitation between alkaloids and tannins, in a liquid solution, by absorbing the tannins, leaving the alkaloids free to be absorbed by the body
What does glycerin not do very well?
Glycerin will not dissolve or mix with resins or fixed oils, so it is not suitable for resinous or oily herb extracts.
And although it is a good solvent for a few alkaloids, it is generally inferior to water, vinegar, and alcohol for extracting most alkaloidal structures.
Glycerin does not extract volatile oils very efficiently, but it readily mixes with them and preserves them for a short time.
what is glycerine relationship with the skin?
When diluted with water or aromatic hydrosols, glycerin is demulcent and emollient, lubricating, soothing, and protecting to the skin and mucous membranes. When used undiluted, it acts as an irritant that arouses activity.
what are the 6 things that ethyl alcohol cannot extract?
Crystalized sugar Mucilaginous substances Starch Gums Albuminous substances Most Salts
What does Mucilaginous mean?
having a viscous or gelatinous consistency.
“a mucilaginous paste”
(of a plant, seed, etc.) containing a polysaccharide substance that is extracted as a viscous or gelatinous solution and used in medicines and adhesives.
What is Albumin?
Simple water soluble protein
What is the difference between a Gum, a Resin and Balsam?
Balsams are resins or oleoresins containing large proportions of benzoic acid, cinnamic acid, or esters of these acids. In plants, balsams are a combination of resins and essential oils (“Oleoresins”). Examples: Tolu balsam, Peru balsam, and Benzoin.
Resins are non-volatile excretions or secretions of very indefinite composition, and are chiefly oxidation products of essential oils.
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What is “dilute alcohol”?
50% water/ 50% alcohol
What can be extracted with ethanol but not water?
essential oils
What is a fixed oil?
non-volatile oil, usually non-aromatic (vegetable oil)
What is the shelf life of glycerine-based extracts?
About a year
What is the shelf life of alcohol-based extracts?
About 4 - 6 years
What is the shelf life of water-based infusions
1 to 2 days
What kind of wine is most often used for wine infusions?
stronger white wines like sherry, as white wines have fewer tannins and sherry have a higher alcohol content.
What needs to be done in order to increase the shelf life of a wine extraction?
It needs to be fortified by adding alcohol, so that the alcohol content is between 20 to 25%
What is the range of wine extract?
It behaves similar to a water-alcohol menstruum
What is the shelf life of a vinegar based extract?
About 6 months
What is the shelf life of an oxymel?
About 6 months, refrigerated
What is the difference between fixed and volatile oils?
volatile oils (a.k.a. essential oils, aromatic oils) are not really oils at all. They are only referred to as oils because they blend with oil quite readily and they react with water much like fixed oils do. Chemically volatile oils have next to nothing in common with fixed oils, lacking both fatty acids and glycerin. They are referred to as “volatile” because, unlike fixed oils, they evaporate readily when exposed to air. We’ll
What are the mineral oils?
Mineral oils are a mixture of liquid hydrocarbons obtained from petroleum, like paraffin wax, and they may be highly volatile or non-volatile.
In regards to fixed oils, what is meant by the “point of congelation”
The point of congelation is the temperature at which a fixed oil will become solid
What is oil a good solvent for?
Oils are good solvents for abstracting resins, oleo-resins, essential oils, and flavonoids.
Name the 3 parts that oils consists out of
olein, stearin, and palmitin. Olein is the liquid portion of fat, and stearin and palmitin are both solid portions; hence, the consistency of fixed oils and fats is due to the relative proportion of these substances.
What are oils broken down into by the digestive tract?
fatty acids, monoglycerides, glycerin
Why should you use distilled water, rather than tap water as a solvent?
distilled water is “soft water”, meaning it has no minerals disolved in it. This makes the solvent “empty” and “hungry”, or less saturated, meaning it will be more effective as an extract.
What is the optimum solution for the extraction of alkaloids?
For preparation of extracts with the highest levels of alkaloids, water/vinegar/alcohol menstrua having a 35 percent water, to 10 percent vinegar, to 55 percent alcohol content are recommended.
What are alkaloids most soluble in?
Most soluble in ether and chloroform, and often less readily in alcohol. In water, they are comparatively insoluble. On the other hand, the solubility of the alkaloidal salts usually follows an opposite pattern: they are freely soluble in water and somewhat soluble in alcohol.
Why is vinegar so good at bringing alkaloids into a solution?
Because vinegar contains acetic acid, which readily binds with Alkaloids to form Alkaloidal Salts which is easily dissolved in water
Which solvent is best used to extract “Balsams”?
Alcohol, as Balsams are essentially resins or oleo-resins derived from essential oils
Which solvent are Balsams insoluble in?
Water
What is the optimal solution for the extraction of the “bitter principal” ?
Most bitter compounds are soluble in water and, on the whole, soluble in alcohol. Optimal amounts of bitters are derived with menstrua having 30 percent to 60 percent alcohol. So lets say 50/50
Which solvent is best used to extract camphor?
alcohol
Are camphors soluble in water?
no
How can camphor be separated from other volatile oils?
by cooling the volatile oils, the camphor begin to crystalize
Which solvents are ideal of extracting essential oils?
there are two ways to extract essential oils, either by steam distillation or by solvent extraction. The best solvents are: Alchohol, oil, and glycerine. They are also slightly soluble in cold water. They will evaporate in hot water
Other solvents used are hexane and also CO2
Which solvent is the best for extracting enzymes?
cold water
Which solvents deactivates or destroys enzymes?
Hot water and alcohol
Which solvents work best for extracting flavanoids?
Flavonoids are soluble in water, in alcohol, and in fixed oils.
What is the optimum solution for extracting clycosides?
between 30 - 60 percent alchohol water solution, so lets say 50/50
Which solvent is best used to extract gums?
cold water
Which solvents are best used to extract gum-resins?
The gum part is soluble in water and the resin part is soluble in alcohol
Which solvent is best used to extract mucilage?
Cold water
Which solvents are best used to extract olieoresins?
fixed oils and alcohol
Which solvent is the best for extracting albuminous matter?
Cold water
How do I filter out albuminous matter from a solution?
either by adding 190 proof alcohol or by boiling to co-agulate the proteins and then filtering it.
Which solvent is the best for extracting resins?
Resins are soluble in alcohol, fixed oils, and essential oils,
What are the best solvents for extracting Saponins?
saponins are readily soluble in water and also soluble in dilute alcohol.
Which solvents are best for extracting starch?
They are insoluble in ordinary solvents, but swell in boiling water to form a peculiar jelly-like or mucilaginous paste
Which solvents are best for extracting Sugar?
Soluble in water, and soluble in dilute alcohol.
What is the best solution for disolving tanins?
Tannins are very soluble in water, soluble in glycerin, and somewhat soluble in alcohol. One can achieve an excellent “tannin tincture” using a menstruum of merely 20 percent alcohol, 80 percent water.
What do tannins readily bind with?
alkaloids, proteins, and metalic salts such as iron
How are waxes different from fats?
Waxes are compounds of fatty acids with certain alcohols. They differ from fats in that they contain no glycerin.
