Terpenoids(isoprenoids).Chemical analysis of iridoids. Analysis of herbs and medicinal herb material containing iridoids

The terpenoids sometimes called isoprenoids, are a large and diverse class of naturally occurring organic chemicals similar to terpens, derived from five-carbon isoprene units assembled and modified in

thousands of ways.

Terpenoids are extraordinarily diverse but they all originate through the condensation of the universal phosphorylated derivative of hemiterpene, isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) giving geranyl

pyrophosphate (GPP).

In higher plants, IPP is derived from the classic mevalonic acid pathway in the cytosol but from the methylerythritol phosphate pathway in plastids. It is generally accepted that the cytosolic pool of IPP serves as a precursor of sesquiterpenes, triterpenes, sterols and polyterpenes whereas the plastid pool of IPP provides the precursors of mono-, di- and tetraterpenes

A rational classification of the terpenes has been established based upon the number of isoprene (or isopentane) units incorporated in the basic

molecular skeleton:

Importance of terpenoids

Plant terpenoids are used extensively for their aromatic qualities. They play a role in traditional herbal remedies and are under investigation for antibacterial, antineoplastic, and other pharmaceutical functions.

Iridoids

Iridoids are a class of secondary metabolites found in a wide variety of plants and in some animals. They are monoterpenes biosynthesized from isoprene and they are often intermediates in the biosynthesis of alkaloids.

Chemically, the iridoids usually consist of a cyclopentane ring fused to a six-membered oxygen heterocycle. The chemical structure is exemplified by iridomyrmecin, a defensive chemical produced by the iridomyrmee genus, for

which iridoids are named.

Bioactivities of iridoids

Iridoids are found in many medicinal plants and may be responsible for some of their pharmaceutical activities. Iridoids exhibit a wide range of bioactivities including stimulation of secretions in the gastrointestinal tract, choleretic, antimicrobial, cardiovascular and sedative (valeopotriates), antihepatotoxic, diuretic (catalpol), hypoglycemic, analgesic, anti-inflammatory, antimutagenic, antispasmodic, antitumor (valtrate), antiviral, immunomodulator, and purgative activities.

Classification

1. Cyclopentan C8,C9,C10 and C14 types (Loganin, aucubin).

2. Secoiridoids. Cleavage of bound in thecyclopentane ring gives rise to secoiridiids. (Secologanin, gentiopicroside, oleuropine)

3. Iridoids of plant from family Valerianaceae Bicyclic monoterpens or valepotriates (‘Valeriana – Epoxy – triester’) Valtrate, dihydrovaltrate.

4. Iridoids-alcaloids – complex of indole alcaloids containing as non-amine part iridoid

BASBAS:: Leaves contain bitter amorphous glycoside of meniantin, at a hydrolysis fissioning on glucose and meniantol; alkaloid of gencianin, flavonoids of rutins and giperozid, ascorbic acid, and also tannic matters to 3%. Roots contain glycoside is a meliatin, tannic matters, inulin, pectin matters and tracks of alkaloids.

FOLIA MENYANTHIDIS TRIFOLIATAEMenyanthes trifoliata - BogbeanMenyanthaceae

Pharmacological activity: natural physiological stimulant of secretion of saliva, gastric juice, bile and digestive enzymes; protivoskleroticheski operates; the presence of organic compounds of iodine in the leaves of watch hinders to the accumulation of cholesterol in an organism

Dosage forms:: Water extract. Enters in the complement of Water extract. Enters in the complement of appetizing, sedative collections.appetizing, sedative collections.

HERBA CENTAURIICentaurium erythraea (С. minus, C. umbellatum)Centaurium pulchellum (SW) DruceGentianaceae

BASBAS::. A plant contains 0,6-1% alkaloids, among them basic gencianin (eritricin): glycosides (genciopikrin, eritrocentaurin, eritritaurin); flavonovyy glycoside of centaurin, oleanolovuyu and ascorbic acids, essential oil, resins

Pharmacological activity: Preparations of centaury as bitter taste is excited appetite, strengthen the secretion of digestive glands, strengthen zhelcheotdelenie, possess poslablyayuschimi and by protivoglistnymi properties (genciopikrin).

Dosage forms:: A grass of centaury is in packs. Extract. Collections appetizing and stomach.

The dry rhizome and roots of Gentiana lutea

BASBAS:: gentiopicrin, gentisin, The root also contains from 12 to 15 per cent. of glucose (gentianose), but is remarkable in that it contains no starch, calcium oxalate, or tannin.

Preparation of Gentisic Acid : The alcoholic extract is washed with water, then with ether. The residue dissolved in alcohol yields the acid on evaporation.

ACTION AND USES.—Simple bitter tonic, long known and very valuable. Dose: 5 to 30 gr. (0.3 to 2 Gm.).

VIBURNUM OPULUS—CRAMP BARKThe dried bark of Viburnum opulus

BASBAS:: A brown resin, a bitter principle (viburnin), valerianic acid, tannic acid, oxalic, malic, and citric acids, sulphates, and chlorides, opulus iridoid

ACTION AND USES: Diuretic, and a tonic and sedative to the uterine and ovarian nerve centers; used in threatened abortion. Dose: 30 to 60 gr. (2 to 4 Gm.). Claimed to be antispasmodic, hence the name cramp bark. Dose: 30 gr. to 2 dr. (2 to 8 Gm.).

VALERIANA—VALERIAN rhizome and roots of Valeriana officinalis

BASBAS:: Besides the common vegetable principles, it contains a terpene, isovaleric acid, and a volatile oil of complex constitution, consisting mainly of an alcohol, borneol; its ether, and its formic, acetic, and valerianic acid esters, which are gradually decomposed on exposure, liberating the acids. This oil (Oleum Valerian.,)

ACTION AND USES.—Gentle nerve stimulant and antispasmodic, employed in hysterical disorders. Dose: 15 to 60 gr. (1 to 4 Gm.).

Radices TaraxaciTaraxacum officinale- DandelionAsteraceae

BASBAS:: Taraxacin (a bitter principle), taraxacerin,resin, inulin, sugar, and mucilaginous substances. Recent investigations have shown the existence of an alkaloid. Preparation of Taraxacin.—Treat decoction with animal charcoal, wash the latter with water, and dissolve out bitter principle with boiling alcohol; evaporate. It has not been proven that this is crystalline. Composition uncertain.

ACTION AND USES.—Deobstruent, tonic. As a remedial agent dandelion root has not been properly appreciated, possibly because it is such a common weed. It is worthy of more study on the part of pharmaceutical chemists and clinicians. The liquid extract and extract are used in hepatic disorders.