1. What is the meaning of terpenoids?
An anthraquinone compound is a component derived from methylpentahydroxy acid, and has a basic skeleton having two or more isoprene units (c5). The open chain terpene has the formula of (c5h8)n, the number of carbon atoms is generally a multiple of 5, and the proportion of hydrogen is generally not a multiple of 8.
Most of the terpenoids are oxygen-containing derivatives having an oxygen-containing group such as an alcohol, an ether, an aldehyde, a ketone, a carboxylic acid, an ester, a lactone or a methylenedioxy group. Some terpenoids exist in the form of glycosides, such as iridoids; some of the terpenoid molecules contain nitrogen atoms, called alkaloids such as aconitine.
2. What types of common terpenoids can be classified into?
According to the isoprene unit (c5 unit), common terpenoids can be divided into monoterpenes, sesquiterpenes, diterpenoids, sesquiterpenes, triterpenes, tetraterpenes and polyterpenes. Each class is further classified according to whether the basic carbon chain is looped or looped.
Monoterpenes: Monoterpenoids can be regarded as compounds obtained by polymerizing two isoprene units and derivatives thereof, which are components of volatile oils. Most have strong aroma and physiological activity. For example, the chain monoterpene geraniol has an antibacterial effect; the monocyclic monoterpene menthol has a antiasthmatic, antitussive and antibacterial effect; the bicyclic monoterpene borneol (borneol) has the functions of sweating, excitement, stagnation and deworming.
Sesquiterpenes: The sesquiterpene compound is a compound obtained by polymerizing three isoprene units and a derivative thereof, and may be present in a volatile oil, and has aroma and biological activity. Monocyclic sesquiterpene artemisinin has an anti-malarial effect.
Diterpenoids: Diterpenoids are compounds obtained by polymerizing four isoprene units and derivatives thereof. The molecular weight increases and the majority are not volatile. Bicyclic diterpenoid ginkgo lactone is an effective drug for the treatment of cardiovascular diseases. Andrographolide has antibacterial and anti-inflammatory effects; tricyclic diterpenoids of triptolide have anti-cancer, anti-inflammatory and anti-fertility effects; The diterpenoid stevioside can be used as a sweetener for sugar-suppressing patients, and its sweetness is 300 times that of sucrose; aconitine of pentacyclic diterpene has analgesic, local anesthesia, cooling, and swelling activity.
Triterpenoids: Triterpenoids are compounds obtained by polymerizing six isoprene units and derivatives thereof. When it exists in a free state, it is called a triterpenoid or triterpene aglycon, and when it is combined with a sugar, it is called triterpenoid saponin.
3. What are the structural types of common iridoid glycosides?
Iridoid glycosides belong to monoterpenoids and are more common in Scrophulariaceae, Rubiaceae, Labiatae and Gentiana. According to its structure, it can be divided into:
(1) Iridoid glycosides
The basic mother nucleus is a cyclomethnonol having a structure of a hemiacetal and a cyclopentane ring, and is mainly present in plants in the form of c1-oh and a glycoside. According to its structure, the presence or absence of a substituent at the c-4 position can be divided into two subclasses; 1 c-4 substituted imidyl glycoside, such as geniposide; 2 c-4 unsubstituted cycloolefin Ethanol glycosides, such as arachidin, sterol glycosides.
A compound derived from the c7-c8 bond opening of an iridoid glycoside. The scutellaria, the scutellaria, and the gentiopicroside in gentian belong to this category.
4. What are the main physical and chemical properties of iridoids and compounds? How to extract and separate them?
(1) Physical and chemical properties
Properties: Iridoid glycosides and cleaved iridoid glycosides are white crystals or amorphous powders, which are optically active, hygroscopic, and bitter.
Solubility: Iridoid glycosides have a relatively small molecular weight, mostly polar functional groups, hydrophilic, easily soluble in water, methanol, soluble in ethanol, acetone and n-butanol, insoluble in chloroform, ether, a lipophilic organic solvent such as benzene. The hydrophilicity of the iridoid glycosides is stronger than that of the aglycones.
Hydrolyzability: Iridoid glycosides are very sensitive to acid, and their glycosidic bonds are easily hydrolyzed by acids. The aglycones formed are very unstable and prone to polymerization. Under different hydrolysis conditions (temperature, acidity, etc.), different colors are produced. Change or precipitation. The processing of black ginseng and rehmannia has become black, which is related to this.
Identification reaction: The molecular structure of the iridoid has a semi-acetal hydroxyl group, which is very active and can react with some reagents to produce a color reaction. It can be used for the identification of iridoids and their glycosides. Such as:
Amino acid reaction: The free aglycone and amino acid are heated to produce a deep red to blue color, and finally a blue precipitate is formed.
Acetic acid-copper ion reaction: Aglycone is dissolved in glacial acetic acid, added with a small amount of copper ions, heated, and reacted blue.
(2) Extraction and separation
Extraction: Iridoid glycosides are generally extracted by a solvent method. The extraction solvent commonly used is water, methanol, ethanol, acetone and the like. When using water as the extraction solvent, calcium carbonate or barium hydroxide should be mixed in the drug to prevent the influence of enzymes and organic acids.
Separation: The extract is concentrated under reduced pressure and then degreased with diethyl ether or petroleum ether, and the iridoid glycoside is extracted with n-butanol; or the degreased aqueous extract is passed through activated carbon or macroporous adsorption resin column. After elution with water to remove water-soluble impurities, the iridoid glycoside is eluted with ethanol.
5. What biological activities are the terpenoids contained in the yew? What are the main physical and chemical properties of paclitaxel?
The yew, also known as yew, contains mainly diterpenoids. The biologically active component is more than 10 compounds of the propylene oxide structure containing c-4, c-5 and c-20 positions in the molecular structure, wherein paclitaxel belongs to the taxane type tricyclic diterpenoid, which has significant anticancer activity. effect.
The free paclitaxel is soluble in organic solvents such as methanol, ethanol, acetone, ethyl acetate, dichloromethane, and chloroform, and is insoluble in water and insoluble in petroleum ether. Paclitaxel contains n atoms, but because it is in the amide state, it is not alkaline, so paclitaxel is a neutral compound. Paclitaxel is stable in the range of ph4~8, decomposes rapidly under alkaline conditions, and is relatively stable to acid. Paclitaxel can be oxidized with a manganese dioxide reagent and is not easily reduced.
6. What are the main physical and chemical properties of terpenoids contained in gentian? How to extract and separate?
(1) Physical and chemical properties
The main iridoids in gentian are gentiopicroside, scutellaria, and scutellaria. Gentiopicroside has a significant bitter taste. Soluble in water, soluble in hydrophilic organic solvents such as methanol, ethanol, acetone, n-butanol, insoluble in lipophilic organic solvents such as chloroform, ether and petroleum ether. The general chemical properties of gentiana glycosides, scutellaria, and the like have iridoid glycosides, such as being easily hydrolyzed by acids, and can react with amino acids, copper ions, shear reagents, and the like.
(2) Extraction and separation
It is usually extracted by methanol or ethanol by percolation. Activated carbon-diatomaceous earth (1:1) was purified and separated by silica gel column chromatography. The gentiopicroside was eluted first, and then the bitter glycosides were eluted.