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Phenols

Various compounds of phenols are common in plant tissues, each of which may enclose a number of grams per every kilogram. Phenol compounds present in plant tissues begin to blend as a result of stimulants on the outer surface like ultraviolet radiation, microbial infections or and chemical changes. Most phenol amalgams are phytochemicals that are basically found in some plant tissues and there are as many as 4000 such compounds.

All plants create numerous organic amalgams that are always not related to the basic metabolism like progress, growth and development and the functions of these natural compounds in plants have only been noticed recently in a diagnostic perspective. Although these organic amalgam produced by the plants do not help in growth, they are effective in other ways. While some of these protect plants from predators and pathogens, others help in the reproductive process by fascinating pollinating agents or scattering the seeds. Many of them are also useful as they help to produce poisons that protect the plants.

Most of the organic products found in plants may be grossly put into three broad categories – alkaloids, phenylpropanoids and terpenoids. While phenylpropanoids are mostly phenolic amalgams, terpenoids are made up of five carbon elements that are blended through the acetate or mevalonate method or the glyceraldehydes 3-phospate/pyruvate process. Many of the terpenoids produced by the plants are a sort of contaminants that protect the plants from being devoured by herbivores creatures or functionally attractants for pests and animals.

Alkaloids, containing nitrogen amalgams, are mainly blended from amino acids and also protect the plants from herbivorous animals and may also be useful pharmacologically. On the other hand, phenolic amalgams are created by through fusion of shikimic acid products and have different functions in plants. Some of the common phenolic amalgams or compounds include tannins, lignans and flavonoids that protect plants from herbivores and other destroyers.

Basically, all phenols and phenolic amalgams are widely found in nature and can also be blended artificially. They form a separate group of chemical substances that comprise a member of hydroxyl cluster linked to an element of hydrocarbon set. Commonly found in substances like antiseptics, resins, plastics, cosmetics, foods and beverages, health aid as well as medicines, these amalgams have varied industrial uses. Many of them like pentachlorophenol find uses in pesticides as well as preservatives for building items, especially wood and rubber. Incidentally, they are grave contaminants and need to be handled carefully as they may contaminate the ground water or pollute the atmosphere during industrial use. Hence, there are several regulations restricting the use of these compounds.

A number of vital vegetation ingredients including tannins, phenolic amalgams, flavones, coumarins, anthraquinones and all their glycosides are comprise phenolic molecules.

Simple phenols

Phenols particles are created when the hydrogen content in a pungent nucleus is swapped with an element from the hydroxyl cluster and this process may happen several times making the isomers include three probable dihydroxylbenzenes as well as three trihydroxylbenzenes. While the dihydroxylbenzenes are hydroquinone, catechol and resorcinol, the trihydroxylbenzenes include benzenitrol, pyrogallol and phloroglucinol. Interestingly, the hydroxyl set in phenol molecule imparts features of alcohol and tends to classify phenols as tertiary alcohols; basically the hydroxyl group in phenol is linked to a dilute carbon nucleus. Thus, phenols are not alcohols, but actually classified under weak acids.

Nearly all phenol byproducts of nearly all phenols are created from several circles and hence they are basically polycyclic molecules changing their basic features. When fundamental elements are replaced by one or more hydrogen, it leads to the formation on simple phenols. The material becomes more bioactive or toxic when these fundamental elements belong to alkyl groups like in eugenol or thymol. Basically, phenols are used to eliminate bacteria, as antiseptics and also as poisons to burn up parasites (anthelmintic). When the crust or the internal arrangement of the cells are deliberately damaged phenols have an antimicrobial effect, and like most antibacterial instruments, slow down leucocyte functioning and leads to crisis in antibiotics like penicillin. Plant tissues containing phenols comprise agents that stimulate leucocyte and recompense, the association of antimicrobial medicines along with substances that weaken the body's resistance power is always harmful.

Salicylic acid

Although not identified specifically, salicylic acid or its properties first came to the light in the 5th century BC when the Greek physician Hippocrates mentioned about a bitter powder removed from willow bark that may perhaps cure pains and diminish fevers. Even the Sumer, Lebanon, and Assyria civilizations made use of this medicine. On the other hand, for years the Native Americans and Cherokee consumed a mixture prepared from the bark to cure fever and other ailments. In fact, the remedial part is found in the inner bark of willow and is generally used in curing pains and other diseases.

The medicinal extract of the bark later came to be known as salicin from Salix alba, which is white willow in Latin. French pharmacist Henri Leroux and Italian chemist Raffaele Piria were the first to extract the medicinal substance and store it in a crystalline form in 1828. Next, they transformed the substance into sugar and another element which after reaction with oxygen turned to salicylic acid (SA).

Ever present in plants, salicylic acid is basically a phytohormone and a phenol that is responsible for numerous functions, including photosynthesis, growth and maturity, transportation, transpiration, ion consumption and also brings about certain changes in the leaf structure and chloroplast formation. At the same time, owing to phenol content, salicylic acid also plays a vital role in plant defense by protecting it from pathogens and also helps in the manufacture of pathogenesis - related proteins that increase the resistance power in pathogens. Salicylic acid is obtained by bio synthesis of amino acid phenylalanine.

Salicylic acid, found widely as ester methyl salicylate in many plant groups, is the base for all medicines in the aspirin group. Salicylic acid imparts the active (aglycone) factor to glycosides like salicin from the willow (Salix spp.) and poplar (Populus spp.) groups, gaultherin from wintergreen (Gaultheria procumbens), birch (Betula spp.), and Indian pipe (Monotropa uniflora) and from cramp bark (Viburnum opulus) and black haw bark (Viburnum prunifolium); populin from the poplar family. In 1839, German researchers also extracted salicylic acid from meadowsweet (Filipendula ulmaria, earlier categorized as Spiraea ulmaria). Although this extract was helpful in curing a number of ailments, it also had adverse side-effects like bleeding, diarrhea, gastric irritation and even resulted to death following over doses.

Interestingly, aspirin has derived it name from the previous botanical name of meadowsweet – Spiraea and salicylic acid got is name from the fact that it was first extracted from the bark of willow tree. As salicylic acid is a carboxylated phenol, it is a very sturdy antiseptic.

Contrary to salicylates, esters and salts are less vigorous and hence not as much of infuriating to the stomach lining and in fact, when acetylsalicylic acid was manufactured in bulk it was found to have little irritating effect. A vital function of the salicylates is to restrain the agents of swelling, irritation and prostaglandins that might otherwise even result to blood clotting in the body. Pharmacologically speaking, salicylates are very vigorous and when used externally they are feeble anodynes and cause irritation. However, small concentrations of salicylates found in some plants help in the renewal of epithelial tissues.

When used internally, salicylates help in creasing the flow of blood in the surrounding area and also increase sweat formation owing to they strong antipyretic nature. These are a result of an express exploit on the thermogenic hub in the hypothalamus. Salicylates enhance the body heat in to recompense the temperature loss in persons with pyrexia and also act on the liver cells (hepatocytes) by augmenting the amount and concentration of bile. In fact, salicylates are catabolic in nature and hence enhance sulphur and urinary urea secretion from the body and also augment uric acid concentration.

Salicylates are contra-indicated in gout, as along with the above functions, they also lead to foster uric acid discharge in the kidney and have a mild diuretic consequence. On the other hand, everyone is aware of the analgesic functions of salicylates and this is the primary result on the acuity of aches or might engage action on prostaglandin metabolism, or both.

In acidic conditions, byproducts of salicylates transform into salicylic acid offering useful antiseptic results that in areas of acute pains like arthritic joints and in urinary tubules. Recently, medicos are using the anti-clotting features of salicylates as a prophylactic healing for thrombotic state. As the issue is still being researched, much cannot be yet said about the usefulness of the plants containing salicylates in this regard. On the other hand, the oil of wintergreen that contains methyl salicylate is applied externally and is very useful as a rubefacient that quickly gets soaked up by the skin. This makes the substance a valuable medicine for curing inflamed joint as it not only diminishes the inflammatory procedure, but also effortlessly augments the flow of blood in the area.

Salicylates are known to have serious side-effects like generating numerous bleedings in the stomach particularly if they are used in a concentrated state. Although not so grave always, salicylates led to stomach hemorrhage in almost all people at some time or the other and in such cases meadowsweet extracts are the best to heal the damage. This is an irony indeed and is generated by the amalgamation of mucilages and tannins, which is normally abandoned during the conservative study of medicinal plant chemistry.

Many skin-care products use salicylic acid as the main constituent for curing acne, psoriasis, corns, calluses, warts and keratosis pilaris, as it can easily marsh the epidermis and check the pores from choking up and making room for new cells. Salicylic acid also forms an ingredient of many shampoos to cure dandruff and in gels to eliminate warts owing to its stimulation on epidermal cells. However, use of intense salicylic acid suspensions many be harmful for dark complexioned people and also for those who do not use sun blocks. These type of people are susceptible to hyper-pigmentation and un-pretreated skin.

Salicylates have other medicinal qualities too and since long have been used to get respite from fever and remedies for inflammatory diseases. To refresh the skin, salicylic acids may be used by drenched in cotton fillings. Sub-salicylate together with bismuth materializes into Pepto-Bismol, a commonly used medicine for tummy reprieve. Blended together the two ingredients not only form a moderate antibiotic, but also an effective remedy for nausea, diarrhea, gas and heartburn.

Eugenol

A member of the allybenzene category of chemical amalgams, eugenol is basically a guaiacol formed by replacing an allyl chain. Normally, eugenol is a light yellow slippery fluid obtained from vital oils like nutmeg, clove oil, bay leaf and cinnamon. Soluble to some extent in water and other organic fluids, eugenol smells pleasing, peppery and clove-like. Cloves, biologically called Syzygium aromaticum, syn. Eugenia aromaticum or Eugenia caryophyllata, are actually dried scented flower buds from a tree belonging to the Myrtaceae group that is commonly found in Indonesia, Zanzibar and Madagascar and is popularly exploited as a spice everywhere. Deriving its name from the French word ‘clou' meaning a ‘nail', cloves are also cultivated in India and Sri Lanka and they get their fragrance from the chemical substance called eugenol. Present in cloves in as high quantity as 72-90 percent, eugenol possesses distinct antiseptic and anesthetic qualities.

The substance has multiple uses, including in perfumeries, flavorings, edible oils and medicines. In medicines, eugenol is commonly used as local antiseptics and anesthetics. Although most of vanillin is produced artificially from phenol or lignan, eugenol is also widely used to produce isoeugenol for further manufacture of vanillin. Blending eugenol and zinc oxide results into zinc oxide eugenol that is used for interim filling and cementing decayed teeth. It also has antibacterial and anesthetic properties and is classified as an intermediary curative substance.

Interestingly, eugenol shows the normal anesthetic and antiseptic qualities of phenols and hence has been used to get relief from tooth aches and also used as antiseptic mouthwash. It also has all other qualities of clove oil and can be used externally as counter-irritant and internally to stimulate saliva discharge to control gastronomic functions. When used inside the intestines, the chemical functions as carminatives and also to avoid irregularities.

Thymol

Thymols, used as antiseptics, local anesthetics, preservatives as well as cooling agents, are outsized, pale and semi-transparent hexagonal sparklers or crystals which are perfumed like thyme and have a sharp and scented taste. Thymol is an ingredient used in lip creams, toothpaste, mouthwash as well as liniments and also locally applied as an irritant and anesthetic to skin and mucous membrane. The chemical does not match well with macrobiotic substances, oxidizing agents or strong bases and it is harmful if taken internally. Hence, swallowing, inhaling or allowing thymol to be soaked in the skin is dangerous. Thymol causes irritation when it comes in contact with eyes, skin and the respiratory system.

Obtained from the oil of thyme (Thymus vulgaris) and present in perfumed labiates, especially in horsemint (Monarda punctata), thymol is a useful antifungal negotiator. It is normally used at intensities of 1-2 percent (thyme oil contains 20-30 per cent). Thymol is also an effective medicine to get relief from oral and intestinal diseases and compared to phenols, it is 20 times stronger as an antiseptic. Thymol is also an efficient anthelmintic. Interestingly, although thymol is much more resilient than phenol, it has less mucosal aggravating qualities than any member of the cluster. Since thymol is rarely taken in by the body fluids, it is mainly used externally.

Hydroquinone

Hydroquinone is the aglycone of arbutin commonly present in the heather group – Ericaceae and Rosaceae. Interestingly, hydroquinone is full of arbutin and is usually applied as a urinary antiseptic, as arbutin is translated into hydroquinone in the urine. Like other members of the phenol family, hydroquinone has antiseptic properties especially against Klebsiella and Escherichia coli.

A topical skin lightening mediator, hydroquinone reduces the creation of melanin in the skin. Frequently described as a bleaching cream that eases pigment clusters, the effect of hydroquinone can be invalidated by rendering the skin to ultraviolet light. As the exposure of the sun can invalidate the action wrought by hydroquinone, a sunscreen is normally added to it during its manufacture. Hydroquinone is an effective medicine for curing murky skin, age spots, brown spots and melasma.

Hydroquinone is used to treat darkened skin areas which include melasma, freckles, age spots, and brown spots. Hydroquinone reduces manufacture of melanosomes (melanin pigment granules) in the skin's colored cells by slowing down the functioning of tyrosinase, an enzyme required to produce melanin.

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