Terpenes are derived from methylglutaric acid, and the molecular skeleton isisopreneUnit (CfiveUnit) is basicStructural unitAnd its derivatives.These oxygen containing derivatives can be alcohols, aldehydes, ketonescarboxylic acid, esters, etc.Terpenes are widely found in nature and are the main components of some plant essences, resins, pigments, etc.asRose oil、Eucalyptus leaf oil, rosin and so on all contain many kinds of terpenoids.In addition, some animal hormonesvitaminThey also belong to terpenoids.
Terpene [ti e] compounds refer to those with (CfiveHeight)nThe general formula and its derivatives with oxygen content and different saturation degree can be regarded asisopreneorIsopentaneA class of natural compounds linked in various ways.Terpenes are widely found in nature,higher plant, fungi, microorganismsinsect, andmarine organism, there are terpenoids.Terpenes areChinese herbal medicineIt has been found that many compounds are from Chinese herbal medicineActive ingredientThey are also importantNatural flavor, cosmetics andfood industryIndispensable raw materials.Some compounds are also important industrial raw materials, such asPolyterpenechemical compoundrubberIs trans linked isopreneLong chainCompound, isautomotive industry And important raw materials for aircraft industry.
Terpenes have many physiological effects, such as expectorant, cough relieving, wind expelling, sweating, insect repelling, analgesia, etc.naturalessential oilTerpenes and terpenoids in raw materials, availablerectification , Direct steamdistillation、Freezing methodandextraction methodSeparated.Essential oils containing terpenes and their derivatives are widely used in the production of spices.
Monoterpenes
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Monoterpenes refer to those compounds with two isoprene unitsTerpeneAnd its derivatives.MonoterpenesWidely exists inhigher plantInSecretory tissueMost of them arevolatile oilMiddle boiling pointThe main components of the lower part have high boiling points of oxygen containing derivatives, most of which have strong aroma and physiological activity, and are important raw materials for medicine, instrument and cosmetics industries. Some of them do not havevolatility。
characteristic
MonoterpeneCompounds can be divided into acyclic (chain) monoterpenesSingle ringMonoterpene, bicyclic monoterpene.
Monocyclic monoterpenes are derived from the cyclization of chain monoterpenes. Due to different cyclization modes, different structural types are produced. The more important representatives are:Menthone、menthol The phenolic ketone type is a deformed structure type of monocyclic monoterpene, its carbon frame does not conform to the isoprene rule, and its molecule has a seven membered aromatic ringBasic structure, due toKeto groupThe existence ofAromaticity, such as chamberlain.The phenolic hydroxyl group in the phenol ketone molecule is due toAdjacencyElectron withdrawing groupIs more acidic than normalPhenolsStrong, but weaker than carboxylic acid. It is the acidic part of volatile oil. Phenol ketones are often associated with somemetal ionOccurring in bright colorsColor response(e.g. Fe3+、Cu2+Therefore, these reactions are often used to identify phenolic ketones.
There are many structural types of bicyclic monoterpenes, includingPineneTypeCampheneTypeCareneAnd other bicyclic monoterpenes.Among them, pinene type and camphene type are the most stable.In spice chemistry, the compounds of pinene and camphene series are the most important, while other bicyclic monoterpenes need to be further developed.
It mostly exists as oxygen containing derivatives.For example:camphor, borneol.And likeCamphene, daisy alcoholIsoborneolEtc.
a. Camphor: Camphor is one of the most important terpene ketones, which is not widely distributed in nature and mainly exists in the volatile oil of camphor tree.Camphor is importantPharmaceutical industryRaw materials: the output of natural camphor made in China ranks first in the world.Camphor is mainly used in medicineIrritantandCardiotonicIts cardiotonic effect is due to its oxidation into π-Camphor oxideAnd p-oxidation of camphor.
At.LevorotatorexistenceAinariaOfleafandWild chrysanthemumFloristicBudIn volatile oil.Borneol is white flake crystal, which is similar to pepperMintWith sublimation, mp204 ～ 208 ℃, [α] D20+37.7 °（ethanol）And - 37.3 ° (ethanol).The synthetic product isRacemic mixture。Borneol not only has the functions of sweating, excitement, spasmolysis and corrosion prevention, but also has significant antioxidant functionSuhe balsamMatchedSu Bing Dropping PillsInstead of Guanxin Suhe Pill, it has the same effect in treating coronary heart disease and angina pectoris.
2.3.3 Carene type compounds
These compounds mainly include carene, 4-hydroxy-2-Carene、4-acetyl2-carene, 3,4-epoxycarnane, etc.
Although the skeleton structure of some natural monoterpene compounds is derived from isoprene unitSkeleton rearrangement, which does not conform to the rule of end-to-end isoprene, and is classified as irregular monoterpenes.Such compounds that have been separated mainly come fromCompositae, such as pyrethroids,IononeAnd its analogues, such as pyrophenones.
Sesquiterpene
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SesquiterpeneClass A refers to a natural terpene compound that is polymerized from 3 molecules of isoprene and contains 15 C atoms in its molecule.Sesquiterpenes and monoterpenes are the main components of volatile oil. Sesquiterpenes have high boiling points, and most of their oxygen-containing derivatives have strong aroma andbiological activity。
characteristic
(1) Bicyclic sesquiterpene
The more important representative substance is hydrocarbon, which is non benzene corearomatic hydrocarbonCompound, but its basic parent nucleus has lost its aromaticity due to hydrogenation.
When fractionating volatile oilfractionSometimes beautiful blue, purple or green fractions can be seen in, which indicates that there may be similar components, with boiling points between 250~260 ℃, which can dissolve inPetroleum ether、Ether, ethanol, etcOrganic solvent, insoluble in water, but soluble instrong acidIt can be diluted with water and precipitated, so it can be used for 60%~65%sulphuric acidorphosphoric acidExtract, add water to dilute the extracted acid solution, and the like components can be separated out.It can also be used withPicric acidOr threenitrobenzeneAnd other reagents to form πcomplex compoundThe crystal has a sharp melting point that can be identified.
Whether there is any volatile oil in the pre testAzulene, multi-purposeBromination reaction(Sabaty reaction).The method is to take 1 drop of volatile oil and dissolve it in 1mlchloroformA few drops of chloroform solution with 5% bromine added, such as blue, purple or green, will show that it contains derivatives like.Also available for-Dimethyl benzaldehyde-concentrated sulfuric acidReagent (Ehrlich reagent) reacts with volatile oil. If purple or red is produced, it is a positive reaction.
S-guaiazuleue is guaiacol, trumpet alcohol orValeriana officinalisglycolIsosulfidation high temperaturedehydrogenationAnd become.chamomileAzulene (C14H16) exists in the volatile oil of chamomile flowerslactoneDehydrogenation of chamomillone lactone can also be prepared.Chamomile azulene has anti-inflammatory effect.
milkmouldAzulene is a component separated from the red antibiotic liquid secreted by lactomyces, which can turn blue in the air.
Specific representatives are as followsGuaiacwood Azulene.
(2) Monocyclic sesquiterpene
The more important representatives areartemisinin: It is an effective antimalarial ingredient in Artemisia annua, and its effective group is intermediateOxygen bridge-O-O -, if broken, it will lose its activity.
(3) Tricyclic sesquiterpene
Extraction and separation
extractSesquiterpeneClass compounds generally adoptSteam distillation, organic solvent extraction andAlkali soluble acid precipitationMethod, and then applyRecrystallizationandChromatographyEtc.Its qualitative color development mainly depends onThin layer chromatography, heating with concentrated sulfuric acid or sulfuric acidvanillin Color development, and the color will be affected by time and sulfuric acidwater contentHowever, in the chromatographic process, Rf value or solvent position is different from the polarity andchemical propertyIt has a close relationship, which has a certain reference value for estimating its attribution to hydrocarbons, aldehydes, ketones, ethers, alcohols, esters, acids, etc.
○ 1 Steam distillation: Sesquiterpene is often the main component of the high boiling point part of the volatile oil, which has a great impact on the flavor of the volatile oil. Generally, the volatile oil obtained by steam distillation is fractionated to form the low boiling point monoterpene part, and the high boiling point can be used in the next stepchromatographic separationA variety of sesquiterpenes can often be obtained.
○ 2 Organic solventsextraction method: Will be collected soon and driedCrude drugCoarse powder, extract with petroleum ether to remove grease, and then use ethanol ormethanolExtract, evaporate the solvent, treat with 20%~50% ethanol, try to make sesquiterpenes dissolve in alcohol, and then use benzene, etherethyl acetate, chloroform extraction, respectively evaporate the solvent, according to whether it has a bitter taste, and make qualitative inspection.Sometimes the aboveExtractWhen concentrated, there is crystallization.The above extracts are separated by silica gel or alumina adsorption chromatography, and some of them are very similar in structure and chemical propertiesLiquid-phase separationTo further purify and isolate the pure product.It should be noted that the petroleum ether extract may contain sesquiterpene lactones, which can be directly concentrated and crystallized or purified by chromatography.
○ 3 Alkali soluble acidPrecipitation method: Many sesquiterpenoids have lactone structure, which is in theHot alkaliThe solution is opened to form salts and dissolved in water. After acidification, the original compound is obtained by closed-loop reaction.This property can be used to extract or purify sesquiterpene lactones.However, when acid-base treatment is used, the configuration may be changed, and attention should be paid during operation.
○ 4 Systematic extraction and separation method: the crude powder of traditional Chinese medicine is extracted with etherextractSoluble in methanol, frozen at - 20 ℃ to partially remove oil, ester, vinegar andTriterpene、SteroidClass impuritiesSilica gel columnPre classification: petroleum ether, petroleum ether ether, 9:1, 3:1, 1:1;Ether and ether methanol (9:1) elute successively.The petroleum ether elution part is mainlyHydrocarbonsIncluding sesquiterpenesalkane、olefinAt 9:1, the elution part is mainly ether（Oxygen ringCompounds), aldehydes, ketones, 3:1 part for aldehydes, ketones, esters (lactones), 1:1 part for lactonesHydroxy compound, the ether part is hydroxyl andPolyhydroxy compoundsEther methanol (9:1) is a polyhydroxy compound and carboxylic acid.These general empirical rules are mainly determined by the polarity of compoundsfunctional groupThe compound of depends on the polarity.Natural steroidstriterpenoidBecause of its large molecular ratio, its esters often appear in the petroleum ether ethanol (9:1) part, and monohydroxy compounds appear in the 3:1 part.Each part shall be chromatographed or separated by preparative thin layer chromatography. Generally, each part can be comprehensively inspected according to this method, or individual parts can be separated.
Diterpene
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definition
DiterpenoidsThe compound can be regarded as a natural terpene compound with 20 C atoms in its molecule, which is polymerized from 4 molecules of isopreneDiterpeneClass A has large molecular weight and poor volatility, so most of them can'tSteam distillation, rarely found in volatile oils, and diterpenoids found in individual volatile oils are also mostly found at high boiling pointsfractionMedium.Diterpenoids are mainly composed of resinslactoneOr glycosides in nature.
characteristic
(1) Tricyclic diterpenoids
The more important ones areTanshinoneClass compounds, triptolide, etc.
Important representatives areStevioside , is a tetracyclic diterpene glycoside, and its sweetness is aboutsucrose300 times of, which can be used asdiabetes、obesityandheart diseaseSucrose substitute for patients.
BesidesGenkwan ester A, ester ethyl and other diterpene lactones with anti-cancer activity.
Bisquiterpenes can be regarded as compounds composed of 5 isoprene, and the total amount of this kind of components is small, such asfuranHypsin-3, etc.
Iridoids are a special class of monoterpenes.It was first obtained from the secretions of Yi ant, once called Yi ant lactone, and was the first antibiotic found in animals.Nowadays, many iridoids have been isolated from many plants, and they have various physiological activities.
structure type
The secondary development of iridoids has a large number of derivatives, whose structural characteristics are: (1) Most of the C1 position existsfunctional group, may be hydroxylMethoxyOr keto;And C1-OHIt is very active and easy to combine with sugar to form glycosides.(2) C3 and C4 mostly have double bonds, and C4 methyl is easily oxidized to CHtwoOH、-CHtwoOR, - COOH, - COOR, etc.(3) IntramolecularCyclopentaneSome show differentOxidation state。
The iridoids can be divided into iridoids and their glycosides, and secoiridoids and their glycosides.
(1) Iridoids and their glycosides
According to the presence of C4 position in the iridoid structureSubstituent, and can be divided into two types.
Both of them are the effective ingredients for lowering blood sugar in rehmannia glutinosa.
b. 4-substituted iridoids and their glycosides
Important representatives include gardenosideGardenoside。
(2) Secoiridoids and their glycosides
Secyclic iridoids are derived from the ring opening of cycloenes at C7 and C8, such as gentiopicroside in the traditional Chinese medicine Gentiana scabra, which is extremely bitter and bitter.Such as gentiopicroside.
Physical and chemical properties
(1) Character
ordinaryCycloeneEther compounds are generally liquid orBi-Sn Solid, white crystal or amorphous after glycoside formationHygroscopicityThis kind of compound is generally bitterChinese herbal medicineOne of the components with moderate bitter taste, and there arechiralityC，The old capital hasoptical rotation。
These compounds are sensitive to acids,Glycosidic bondEasy to beacid hydrolysisFractureAglyconeWithSemiacetalThe structure and property are active, and it is easy to further polymerize, so it is difficult to obtain aglycones of original glycosides after hydrolysis, and different color precipitates will be produced with different hydrolysis conditions.Therefore, acid hydrolysis reaction can be used to check the existence of iridoid glycosides in plants.commonlyplant tissue Melatonics can often be used as a clue to the existence of iridoid glycosides.
Because of the structural characteristics of aglycones, iridoid glycosides can also color react with some reagents, and can also be used as a qualitative detection method for such components, such as:JingnipingAndamino acidThe blue purple precipitate formed by the reaction under the heating condition can also dye the skin blue purple in contact with the skin;Dissolve the sample in iceacetic acid, add a small amountCopper ionWhen heated, a blue reaction is produced;Shear reagent（Concentrated hydrochloric acid1 Volume vsaniline 15 volumeMixed liquid）It often produces special color reaction with piperan derivatives, such asCloverIt reacts with Shear reagent to produce yellow, then turns brown, and finally turns dark green.
In the same plant, there are often manyStructural similarityTo further separate the single component, we can usesilica gel、aluminaBy 2020,High performance liquid chromatographyIt has also been widely used for the separation of iridoid glycosides, and sometimes derivatives, such as acetyl compounds, are needed to achieve effective separation.
