Iris, Irises

germanica L., 

 

 

Homeland of I. germanica L. and I. pallida Lam. unknown. I. florentin a L. grows in the Mediterranean and the Arabian Peninsula. All three species are widely cultivated both in the Mediterranean states and in the states of Asia Minor to Kashmir and Nepal.

All three species are perennial monocotyledonous herbaceous plants with a large, oblique, slightly branched rhizome, supplied with numerous roots on the underside. At the anterior end of the rhizome, 4-6 leaves are produced. Leaves up to 1 m tall, bluish-green, matte, xiphoid, entire with parallel venation. The stem bears several large beautiful flowers. Perianth simple, corolla; 3 outer lobes are bent down, 3 inner ones are up. Stamens 3, they are located above the recurved lobes. Ovary inferior, three-celled, with filiform column and 3 petal-like wide stigmas covering stamens; the Germanic iris flowers are dark purple, the Florentine ones are white, the pale ones are light purple, fragrant. Their roots are the same.

On plantations, the rhizome is harvested in the second and third year in the fall. Cut the leaves with the growth part of the rhizome (which serves as planting material) and roots. The rhizomes cut in this way are washed with water, then carefully cleaned with a knife from the outer cork and immediately thrown back into the water to prevent browning. After washing, they are laid out in a layer on mats and dried in the sun. Freshly dug rhizomes have a grassy smell and only with slow air drying does a pleasant violet smell appear, which explains the name of the raw material.

Violet root (Rhizoma Iridis) is a dense, heavy, white rhizomes, flattened, constricted, often with 1-2 branches. On the underside there are numerous round dark scars from cut roots. On the upper convex side there are roller-like thickenings and transverse rows of small dark dots – traces of leaf veins.

The rhizome contains essential oil – 0.1-0.2%. Oil at traditional temperature is dense; 80-90% of odorless myristic acid and 10-20% of odor carriers can be isolated from it; the main one is the monocyclic terpene ketone iron. Iron is a mixture of 3 isomers a-, – and g-irons.

In addition to iron, traces of benzaldehyde, linalool, geraniol, etc., add aroma to the essential oil.

 

Violet root in medicine is used in cough preparations, for flavoring powders, and is often included in tooth powders. It is widely used in perfumery.

The plant contains aromatic and phenolic compounds.

 

PLANTS CONTAINING AROMATIC AND PHENOLIC COMPOUNDS

Aromatic compounds in essential oils are represented by oxygen derivatives, of which the following are the most common.

 

Phenols in essential oils are represented by both individual compounds and phenol esters. The most common are the following.

 

PLANTS CONTAINING ESSENTIAL OILS

Essential oils are natural aromatic substances that are highly volatile and cause the specific smell of plants. For this reason, also due to their “oily” consistency and “greasy” stain on paper, which soon disappears, they received such a peculiar name.

Essential oils are not individual substances. These are complex mixtures of organic substances, the composition and number of which are different for each type of essential oil plants and can serve as a chemotaxonomic feature. The main group of substances that make up the essential oils of many plants are terpenes (more precisely, monoterpenes) and seseviterpenes, i.e., substances with an isoprenoid structure. However, in the essential oils of a number of plants, aromatic compounds may predominate, as well as numerous substances of the aliphatic series. There are plants with sulfur and nitrogen compounds in essential oils.

Essential oils in plants are mostly in a free state. However, some plants contain them in the form of glycosides and are released during enzymatic cleavage. Essential oils are formed in all parts of plants, but quantitatively they accumulate in them traditionally unequally.

They can be in a plant organism in a diffuse diffuse state (ie, emulsified or dissolved in cells) or accumulate, localize in special anatomical and morphological formations that are easily detected under a microscope. These excretory formations can be exogenous and endogenous.

Exogenous formations develop in the epidermal tissue and are:

– glandular “spots” – small-drop accumulations of essential oils immediately under the cuticle of the epidermis;

– glandular hairs – cylindrical epidermal outgrowths, consisting of a unicellular or multicellular pedicle and a head with cells that secrete essential oil;

– glands – epidermal outgrowths that have received the most

the highest specialization in the extraction and accumulation of essential oils. They have a different structure and can serve as a systematic feature. For example, in yasnotkovye (labial) 8 excretory cells are arranged in a rosette on a short stalk; in aster (composite) glandular cells have a vertical arrangement – 2 in 4 rows, etc.

Endogenous formations develop in parenchymal tissues and are:

– secretory cells – single (for example, in the air parenchyma of calamus rhizome) or form layers of such cells (for example, in valerian roots);

– receptacles – rounded cavities formed in the mesophyll of the leaf, peel of citrus fruits, in the bark and wood of a number of plants and filled with essential oil;

– tubules and passages – strongly elongated excretory formations found in the fruits of umbellate, bark and wood of a number of plants.

Essential oils accumulate in plants in all possible quantities: from hundredths and thousandths of a percent (for example, in violet flowers – 0.004%) to 20% or more (for example, in flower buds of carnations – up to 23%).

Essential oils are obtained: 1) by steam distillation; 2) extraction with some extractants; 3) enfleurage; 4) mechanically.

Steam distillation is the most common method. It is carried out in installations consisting of a double-jacketed still (in which steam circulates to prevent the still from cooling), a condenser and a receiver. Steam is fed into the cube loaded with raw materials from below through a perforated coil, entraining the essential oil. A mixture of cooled vapors of water and essential oil enters the receiver, where the mixture separates and excess water is removed through a tube at the bottom of the receiver (if oil is lighter than water) or through a drain tube at the top (if oil is heavier than water).

The extraction of essential oils from raw materials is carried out with volatile organic solvents in Soxhlet-type apparatuses or in column apparatuses. Subsequently, the raw material is lifted by the screw from the bottom up, and the extractant enters towards it. After distillation of the solvent, the residue is either pure essential oil or its mixture with other extracted substances (resins, waxes, etc.); in the latter case, additional cleaning is required.

Enfleurage is based on the fact that essential oil from raw materials (mainly from flowers) is absorbed by sorbents (solid fats, activated carbon, etc.) in special frame installations.

The mechanical method is used to extract essential oils from citrus fruits by pressing or scraping.

Although essential oils are very common in the plant world, their role for the plant organism and the reasons for their formation have not yet been reliably established. It was assumed that essential oils serve to protect plants from diseases and pests, to attract the smell of insects, which contributes to the pollination of flowers, to protect plants from excessive heating during the day and hypothermia at night, etc. Currently, most scientists believe that essential oils (or rather, their components) are actively involved in the metabolic processes of plant organisms.

Essential oils find a wide and varied application for medicinal, cosmetic, food (spices) and other chains.

Essential oils are classified according to the substances that make up their bulk, or substances that determine their medicinal and industrial value. There are the following groups (and subgroups) of components of essential oils:

Monoterpenes (terpenes), including:

1. Acyclic terpenes.

2. Monocyclic terpenes.

3. Bicyclic terpenes.

Sesquiterpenes, including:

1. Acyclic sesquiterpenes.

2. Cyclic sesquiterpenes.

Aromatic and phenolic compounds.

Sulfur and nitrogen-containing compounds.

The listed compounds, especially terpenoids, in essential oils can occur in the form of numerous oxygen derivatives: alcohols, aldehydes, ketones, phenols, acids, esters, lactones, oxides, quinones. The number of terpenoids also increases due to the tendency of many of these compounds to various forms of isomerism (optical, geometric, etc.).

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