ANTIOXIDANTACTIVITYANDPHYTOCHEMICALPROPERTIESOF AQUEOUS EXTRACTS OF Spondias mombin STEM BARK AND ROOT
In tradictional setting, Spondias mombin is used in the management of different ailments. This has been attributed to its rich phytochemical and antioxidant properties. Therefore, this study evaluated the phytochemical as well as antioxidant activity of aqueous extracts of Spondiasmombin. The extracts of Spondiasmombin were investigated for phytochemical such as tannins, saponins, alkaloids,total flavonoids, total phenol and proanthocyanidin, while the in vitro antioxidant activity were determined using ferrous metal chelating assay, antioxidant power assay, ferric reducing antioxidant power (FRAP) assay, 1,1-diphenyl-2,2-picry-hydazyl (DPPH) radical scavenging assay. Result obtained for phytochemical studies reveal that phenolic content was highest in the aqueous extract of Spondiasmombin stem bark as against aqueous extract of Spondias moimbin root which have a low phenolic content. Also, proanthocyanidin was highest in aqueous extract of Spondaismombin root and low in aqueous extract of Spondiasmombin stem bark. Qualitative study show the presence of the various pyhtochemicals in varying amounts, however, alkaloid were absent in both aqueous extract of spondiasmombin root and stem bark, tannins were present only in aqueous extract of Spondiasmombin stem bark, while cardiac glycosides were present only aqueous extract of Spondiasmombin stem bark. The aqueous extract of Spondiasmombin stem bark showed the best IC50 value (2.66 ×109) for 1,1-Diphenyl-2,2-picry-hydazyl (DPPH) radical scavenging activity, when compared with root extract, but, was significantly (p<0.05) higher than that of the standard, vitamin C (1.281). Also, aqueous extract of Spondiasmombin stem bark showed the best IC50 for ferrous metal chelating assay when compared with the root extract, but was significantly (p<0.05) higher than that of standard, (EDTA) (4.031). Therefore, Spondiasmombin has a great potential for use as a natural source of antioxidants against free radical damage.
TABLE OF CONTENTS
Title page - - - - - - - - - - ii
Certification - - - - - - - - - - iii
Dedication - - - - - - - - - - iv
Acknowledgement - - - - - - - - v
Table of content - - - - - - - - - vi
Abstract - - - - - - - - - - ix
1.0 INTRODUCTION - - - - - - - - 1
1.1 LITERATURE REVIEW - - - - - - - - 3
1.2 Plant Morphology - - - - - - - - 3
1.2.1 Scientific classification - - - - - - - 4
1.2.2 Common names of Spondiasmombin - - - - - 5
1.2.3 Non-Medicinal Uses- - - - - - - - 5
1.2.4 Medicinal uses - - - - - - - - 7
1.2.5 Biological Activities of Plants - - - - - - 8
1.3 Antioxidant - - - - - - - - - 9
1.4 Phytochemical - - - - - - - - 13
1.4.1 Phytochemical as candidate of nutrients - - - - 13
1.4.2 Food and Phytochemical - - - - - - - 14
1.4.3 Flavonoid - - - - - - - - - 14
1.4.4 Tannin - - - - - - - - - 18
1.4.5 Phenol - - - - - - - - - 22
MATERIAL AND METHOD
2.1 Chemicals and Reagents - - - - - - - 28
2.2Equipment and Apparatus - - - - - - - 29
2.3 Collection and Identification of plant - - - - - 31
2.4 Preparation of plant Extracts - - - - - - 31
2.5 Qualitative phytochemical analysis - - - - - 32
2.6 Quantitative Analysis Phytochemical screening - - - 33
2.6.1 Determination of total flavonoid content - - - - 33
2.6.2 Determination of Total Phenolic Content - - - - 34
2.6.3 Determination of proanthocyanidin content - - - - 34
2.6.4 Determination of total Tannin - - - - - - 35
2.6.5 Estimation of diphenyl-picryl-hydrazyl (DPPH) Radical - - 35
2.6.6 Ferric Reducing Antioxidant Power (FRAP) Assay - - - 36
2.6.7 Reducing Power Assay - - - - - - - 37
2.6.8 Metal Chelating Activity - - - - - - - 37
3.1Result for Percentage Yield - - - - - - - 38
3.2Result for qualitative Phytochemicals assay- - - - - 38
3.3 Result for quantitative phytochemicals assay - - - - 39
3.4 In vitro Antioxidant - - - - - - - - 40
3.4.1 Result for Ferric Reducing Antioxidant Power (FRAP) assay - 40
3.4.2 Result for Ferrous Metal Chelating assay - - - - 41
3.4.3 Result for Reducing Power assay - - - - - - 42
3.4.4 Result for DPPH assay - - - - - - - 43
Discussion - - - - - - - - - - 45
Conclusion - - - - - - - - - - 48
References - - - - - - - - - - 59
In recorded history, medicinal plants have been in use for the treatment of man and animal diseases (Osai et al., 1997). Nowadays the crude extracts and dry powder samples from medicinal and aromatic plants, and their species have been used for the development and preparation of alternative traditional medicine food addictives (Marino et al., 2001). A plant becomes a medicinal plant only when its biological activity has been ethno-botanically reported or scientifically established. In 1978, the World Health Organization (WHO) emphasized the importance of scientific research in the area of herbal medicine.
Biological activities of Spondias mombin include; uterine stimulant actions; smooth muscle relaxant actions; uterine antispasmodic (Uchendu et al., 2008); sedative and anticonvulsant actions, and anti-anxiety actions; anti-inflammatory (Nworu et al., 2011). It has antimicrobial effects that are reported to be as broad spectrum as ampicillin and gentamycin (Abo et al., 1999). Spondiasmombin is also reported to have antibacterial, anti-viral, sedative, anti-epileptic and has anti-psychotic and anti-oxidant effects (Ayoka et al., 2006). Our survival and continued existence in turn depends on the efficiency with which man, with all the resources and technology available to him harnesses, develops and utilizes plants and plant products. The objective of this study is to establish the antioxidant activity of the plant extracts, to screen for and identify the secondary metabolites present in the plant extracts.
Spondiasmombin is a tree, a species of flowering plant in the family Anacardiaceae (Ayoka et al., 2008). It is native to the tropical Americas, including the West Indias. The tree has been naturalized in parts of Africa, India, Sri Lanka and Indonesia. It is rarely cultivated. The mature fruit has a leathery skin and a thin layer of pulp. The seed has an oil content of 31.5% (Aiyeloja et al., 2006).
The plant is medium-sized, occasionally large, tree, with long compound leaves, each leaf has an odd number of leaflets, from 9-19. Usually, the leaves are alternate, but bunched towards the end of the branches, emanating like spokes of a wheel in all directions from the branch. The leaflets are opposite except for the terminal ones. Particularly on young plants, the leaf stalk tends to be reddish towards the outer leaflets. The trunk and bark are gray, and sometimes have distinctive bur, blunt, gray spines
1.2.2 COMMON NAMES OF Spondias mombin IN DIFFERENT LANGUAGE
Spondiasmombin has several common names.In Nigeria, the fruit is called Iyeye or Yeye in Yoruba language, ngulungwu in Igbo and isada in Hausa (Olu, 2008). Throughout the Spanish-speaking Caribbean and Mexico it is called jobo (Oyelade et al.,2005). Among the English speaking Caribbean islands it is known as yellow mombin or hog plum, while in Jamaica it is called Spanish plum, gully plum or coolie plum. In Brazil, the fruit is known by several different names, such as caja, tapereba and ambalo. In Peru, it is hog plum. It is called “Akukor” in the Ewe language of Ghana. Other common names include hug plum, true yellow mombin, golden apple or java plum, ambaralla in Sri lanka.
1.2.3 NON-MEDICINAL USES OF Spondias mombin
The fruits are edible and sometimes called monkey-plum, but the wood is of low quality and seldom used. The bark is used for carving figures, while the leaves and roots are used as medicine.
The yellow mombin is less desirable than the purple mombin and it is appreciated mostly by children and way-farers as a means of alleviating thirst. Ripe fruits are eaten out-of-hand, or stewed with sugar. The extracted juice is used to prepare ice cream, cool beverages and jelly in Costa Rica and Brazil (Keshinro, 1983). It is used in Panama, Peru and Mexico in fairly large quantities as jams. In Amazon, the fruit is used mainly to produce wine sold as “Vinho de Taperiba”. In Guatemala, the fruit is made into a cider-like drink. Mexicans pickle the green fruits into vinegar and eat them like olives with salt and chili, as they do with unripe purple mombin. The fruits are widely valued as feed for cattle and pigs. The tree exudes a gum that is used as glue. The wood is yellow or yellowish-brown with darker markings, light in weight, buoyant, flexible and prone to attack by termites and other pests. It is much used in carpentry, for match sticks, match boxes, physician’s spatulas, stick for sweet meats, pencils, pen-holders, packing cases, interior sheathing of houses and boats and as a substitute for cork. It is not suited for turnery and does not polish well. In Brazil, the woody tubercles on the trunk are cut off and used for bottle stoppers and to make seals for stamping sealing wax.
In tropical Africa, saplings serve as poles for huts, branches for garden poles and for axes and hoe handles. In Costa Rica and Puerto Rico, the wood is employed only as fuel. Ashes from the burnt wood are utilized in indigo-dyeing in Africa. The bark is used in dyeing. It is so thick that it is popular for carving amulets, statuettes, cigarette holders and various ornamental objects. Portable water can be derived from the roots in emergency. The flowers worked intensively by honeybees early in the morning. In Congo the young leaves pounded to a frothy pulp are used as a bed for paralytics, who are then massaged with them to the accompaniment of incantation (Oyoka et al., 2008).
1.2.4 MEDICINAL USES OF Spondias mombin
The fruit juice is drunk as a diuretic and febrifuge. The decoction of the astringent bark serves as an emetic, a remedy for diarrhea ((Akubue et al., 1983), dysentery, haemorrhoids and a treatment for gonorrhoea and leucorrhea (Ayoka, et al., 2008). In Mexico, it is believed to expel calcifications from the bladder. The powdered bark is applied on wounds (Villegas et al., 1997). A tea made from the flowers and leaves is taken to relieve stomach ache, biliousness, urethritis, cystitis and eye and throat inflammations. In Suriname’s traditional medicine, the infusion of the leaves is used as a treatment of eye inflammation, diarrhea and veneral diseases. The extract has shown anti-inflammatory activity (Abed et al., 1996).The leaves are locally used for various digestive problems including stomach aches, dyspepsia, gastralgia, colic, and constipation. It has been reported as a medicinal plant with potentials that is valuable and a source of active drugs for treating diseases that has not been fully tapped (Ayoka et al., 2008).
1.2.5 BIOLOGICAL ACTIVITIES OF Spondiasmombin
All parts of the tree are medicinally important in traditional medicine. The fruits decoction is drunk as a diuretic and febrifuge, the decoction of the bark and the leaves as emetic, antidiarrhoea and used in the treatment of dysentery, haemorrhoids, gonorrhoea and leukorrhea. The antimicrobial, antibacterial, antifungal, and the antiviral properties of Spondias mombin have been reported (Rodrigues and Hasse, 2000). A tea of the flowers and the leaves is taken to relieve stomach ache, various inflammatory conditions and wound healing (Villegas et al., 1997). Offiah and Anyanwu (1989) have also reported the abortifacient activity of the aqueous extract. Preliminary reports suggest that the phenolic acid, 6-alkenyl-salicylic acid from Spondias mombin are responsible for the antibacterial and molluscicidal action of this plant extract. In another study, the anacardis acid derivative from the hexane extract of the plant was showed to possess beta lactamase inhibitory properties (Coates et al, 1994).
Antioxidants are an inhibitor in the process of oxidation, even at relatively small concentration and thus have diverse physiological role in the body. Antioxidant constituents of the plant material act as radical scavengers and helps in converting the radicals to less reactive species. A variety of free radical scavenging antioxidants are found in dietary sources like fruits, vegetables and tea, etc. Oxygen is absolutely essential for the life of aerobic organism but it may become toxic if supplied at higher concentrations. Dioxygen in its ground state is relatively unreactive; its partial reduction gives rise to active oxygen species (AOS) such as singlet oxygen, super oxide radical anion, hydrogen peroxide etc. This is partly due to the oxidative stress that is basically the adverse effect of oxidant on physiological function. Free oxygen radicals plays cardinal role in the etiology of several diseases like arthritis, cancer, atherosclerosis etc. The oxidative damage to DNA may play vital role in aging (Cheesemanet al., 1993) and the presence of intracellular oxygen also can be responsible to initiate a chain of inadvertent reaction at the cellular level and these reaction cause damage to critical cell biomolecules. These radicals are highly toxic and thus generate oxidative stress in plants. Plants and other organism have in built wide range of mechanism to combat with these free radical problems. Free radicals are an atoms or molecules that bear an unpaired electron and are extremely reactive, capable of engaging in rapid change reaction that destabilize other molecules and generate many more free radicals. In plants and animals these free radicals are deactivated by antioxidants. These antioxidants act as inhibitor of the process of oxidation, even at relatively small concentration and thus have diverse physiological role in the body. Antioxidant constituents of plant materials act as radical scavengers, and convert the radicals to less reactive species. Increasing intake of dietary antioxidants may help to maintain an adequate antioxidant status and, therefore, the normal physiological function of a living system. To protect the cells and organ systems of the body against reactive oxygen species, humans have evolved a highly sophisticated and complex antioxidant protection system. It involves a variety of components, both endogenous and exogenous in origin, that function interactively and synergistically to neutralize free radicals (Sulekha et al., 2009).Plants have developed an array of defence strategies (antioxidant system) to cope with oxidative stress.
The antioxidative system includes both enzymatic and non-enzymatic systems. The non enzymatic system includes ascorbic acid (vitamin C); ά-tocopherol, cartenes etc, and enzymic system include superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), glutathione reductase (GR) and polyphenol oxidase (PPO) etc. The intake of antioxidant compounds present in food is an important health-protecting factor. Natural antioxidants present in foods and other biological materials have attracted considerable interest because of their presumed safety and potential nutritional as well as therapeutic effects. Because extensive and expensive testing of food additives is required to meet safety standards, synthetic antioxidants have generally been eliminated from many food applications.
The increasing interest in the search for natural replacements for synthetic antioxidants has led to the antioxidant evaluation of a number of plant sources. Antioxidants that have traditionally used to inhibit oxidation in foods also quench dreaded free radicals and stop oxidation chains in-vivo, so they, are viewed by many as nature’s answer to environmental and physiological stress, aging, atherosclerosis, and cancer. The nutraceutical trend towards doubling the impact of natural antioxidants that stabilize food and maximize health impact presents distinct challenges in evaluating antioxidant activity of purified individual compounds, mixed extracts, and endogenous food matrices and optimizing applications. It is well known that Mediterranean diet, which is rich in natural antioxidants, leads to a limited incidence of cardio- and cerebrovascular diseases. It is known that compounds belonging to several classes of phytochemical components such as phenols, flavonoids, and carotenoids are able to scavenge free radical such as O2˙ , OH˙, or lipid peroxyl radical LOO˙ in plasma. The effective intake of single food antioxidants and their fate in the human body have been defined only for a few compounds. It is reasonable that the higher the antioxidant content in foods, the higher the intake by the human body. Natural antioxidants occur in all parts of plants. These antioxidants include carotenoids, vitamins, phenols, flavonoids, dietary glutathione, and endogenous metabolites. Plant-derived antioxidants have been shown to function as singlet and triplet oxygen quenchers, free radical scavengers, peroxide decomposers, enzyme inhibitors, and synergists. The most current research on antioxidant action focuses on phenolic compounds such as flavonoids. Fruits and vegetables contain different antioxidant compounds, such as vitamin C, vitamin E and carotenoids, whose activities have been established in recent years. Flavonoids, tannins and other phenolic constituents Present in food of plant origin are also potential antioxidants.
A rapid, simple and inexpensive method to measure antioxidant capacity of food involves the use of the free radical 1,1,diphenyl-2-picrylhydrazyl (DPPH). DPPH is used to test the ability of compound to act as free radical scavenging or hydrogen donors, and to evaluate antioxidant activity of food. It has also been used to quantify antioxidants in complex biological system, in recent years, the DPPH method can be used for solid or liquid sample and is not specific to any particular antioxidant component but applies to the overall antioxidant capacity of the sample. There is a parallel increase in the use of methods for estimating the efficiency of such substances as antioxidants. One such method that is currently popular is based upon the use of stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH).
Pytochemicals are compounds that occur naturally in plants (phyto mean “plant” in greek). Some are responsible for colour and other prganoleptic properties, such as the deep purple of blueberries and the smell of garlic. Phytochemicals may have biological significance, for example carotenoids or flavonoids but are not established as essential nutrients. There may be as many as 4,000 different phytochemicals.
1.4.1 PYTOCHEMICALS AS CANDIDATE NUTRIENTS
Without specific knowledge of their cellular actions or mechanisms, phytochemicals have been considered possible drugs for millennia. For example, Hippocrates may have prescribed willow tree leaves to abate fever. Salicin, having anti-inflammatory and pain-relieving properties, was originally extracted from the bark of the white willow tree and later synthetically produced to become the staple, over –the-counter drug aspirin (Sneader, 2000). Some pytochemicals with physiological properties may be elements rather than complex organic molecules. For example, selenium, which is abundant in many fruits and vegetables, is a dietary mineral involved with major metabolic pathways, including thyroid hormone metabolism and immune function. Particularly, it is an essential nutrient and cofactor for the enzymatic synthesis of glutathione, an endogenous antioxidant (Papp et al., 2007).
1.4.2 FOOD PROCESSING AND PHYTOCHEMICALS
Phytochemicals in freshly harvested plant foods may be processing techniques, including cooking (Bongoni et al., 2013). The main cause of pytochemical loss from cooking is thermal decomposition (Palermo et al., 2014). A converse exists in the case of caroteniods, such as lycopene present in tomatoes, which may remain stable or increase in content from cooking due to liberation from cellular membranes in the cooked food (Agarwel et al., 2001) and (Dewanto et al., 2002). Food processing techniques like mechanical processing can also free carotenoids and other phytochemicals from the food matrix, increasing dietary intake (Hotz and Gibson 2007).
Bn 1.4.3 FLAVONOID
Molecular structure of theflavone backbone (2-phenyl-1,4-benzopyrone)
Flavonoids (or bioflavonoids) (from the Latin word flavus meaning yellow, their color in nature) are a class of plant secondary metabolites.Chemically, they have the general structure of a 15-carbon skeleton, which consists of two phenyl rings (A and B) and heterocyclic ring (C). This carbon structure can be abbreviated C6-C3-C6. According to the IUPAC nomenclature, they can be classified into:
⦁ flavonoids or bioflavonoids
isoflavonoids, derived from 3-phenyl⦁ chromen-4-one (3-phenyl-1,4-⦁ benzopyrone) structure
neoflavonoids, derived from 4-phenyl⦁ coumarine (4-phenyl-1,2-⦁ benzopyrone) structure
The three flavonoid classes above are all ketone-containing compounds, and as such, are anthoxanthins (flavones and flavonols). This class was the first to be termed bioflavonoids. The terms flavonoid andbioflavonoid have also been more loosely used to describe non-ketone polyhydroxy polyphenol compounds which are more specifically termed flavanoids. The three cycle or heterocycles in the flavonoid backbone are generally called ring A, B and C. Ring A usually shows a phloroglucinol substitution pattern.
FUNCTIONS OF FLAVONOIDS IN PLANTS
Flavonoids are widely distributed in plants, fulfilling many functions. Flavonoids are the most important plant pigments for flower coloration, producing yellow or red/blue pigmentation in petals designed to attract pollinator animals. In higher plants, flavonoids are involved in UV filtration, symbiotic nitrogen fixation and floral pigmentation. They may also act as chemical messengers, physiological regulators, and cell cycle inhibitors. Flavonoids secreted by the root of their host plant help Rhizobia in the infection stage of their symbiotic relationship with legumes like peas, beans, clover, and soy. Rhizobia living in soil are able to sense the flavonoids and this triggers the secretion of Nod factors, which in turn are recognized by the host plant and can lead to root hair deformation and several cellular responses such as ion fluxes and the formation of a root nodule. In addition, some flavonoids have inhibitory activity against organisms that cause plant diseases, e.g. Fusarium oxysporum (Galeotti et al., 2008).
Flavonoids (specifically flavanoids such as the catechins) are "the most common group of polyphenolic compounds in the human diet and are found ubiquitously in plants" (Spencer,2008). Flavonols, the original bioflavonoids such as quercetin, are also found ubiquitously, but in lesser quantities. The widespread distribution of flavonoids, their variety and their relatively low toxicity compared to other active plantcompounds (for instance alkaloids) mean that many animals, including humans, ingest significant quantities in their diet. Foods with a high flavonoid content include parsley,onions, blueberries and other berries, black tea, green tea and , bananas, all citrus fruits, Ginkgo biloba, red wine, sea-buckthorns, and dark chocolate (with a cocoa content of 70% or greater). Further information on dietary sources of flavonoids can be obtained from the US Department of Agriculture flavonoid database.
A tannin is anastringent, bitter plant polyphenolic compound that binds to and precipitates proteinsand various other organic compounds including amino acids and alkaloids.
The term tannin (from tanna, an Old High German word for oak or fir tree, as in Tannenbaum) refers to the use of wood tannins from oak in tanning animal hidesinto leather; hence the words "tan" and "tanning" for the treatment of leather. However, the term "tannin" by extension is widely applied to any large polyphenolic compound containing sufficient hydroxyls and other suitable groups (such as carboxyls) to form strong complexes with various macromolecules.
The tannin compounds are widely distributed in many species of plants, where they play a role in protection from predation, and perhaps also as pesticides, and in plant growth regulation (Katie et al., 2006). The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of unripened fruit or red wine (McGee and Harold, 2004). Likewise, the destruction or modification of tannins with time plays an important role in the ripening of fruit and the aging of wine.
STRUCTURE AND CLASSES OF TANNINS
There are three major classes of tannins: Shown below is the base unit or monomer of the tannin. Particularly in the flavone-derived tannins, the base shown must be (additionally) heavily hydroxylated and polymerized in order to give the high molecular weight polyphenol motif that characterizes tannins. Typically, tannin molecules require at least 12 hydroxyl groups and at least five phenyl groups to function as protein binders.
Class/Polymer: Hydrolyzable tannins Non-Hydrolyzable
or condensed tannins Phlorotannins
Sources Plants Plants Brown algae
Oligostilbenoids (oligo- or polystilbenes) are oligomeric forms of stilbenoids and constitute a class of tannins (Boralle et al.,1993).
Pseudo tannins are low molecular weight compounds associated with other compounds. They do not change color during the Goldbeater's skin test, unlike hydrolysable and condensed tannins, and cannot be used as tanning compounds. Some examples of pseudo tannins and their sources are (Ashutosh kar, 2003):
Pseudo tannin Source(s)
Gallic acid Rhubarb
Flavan-3-ols (Catechins) Tea, acacia, catechu, cocoa, guarana
Chlorogenic acid Nux-vomica, coffee, mate
Ipecacuanhic acid Carapichea ipecacuanha
Tannins are distributed in species throughout the plant kingdom. They are commonly found in both gymnosperms as well as angiosperms(Simon Mole, 1993). In 1993, Mole studied the distribution of tannin in 180 families of dicotyledons and 44 families of monocotyledons (Cronquist). Most families of dicot contain tannin-free species (tested by their ability to precipitate proteins).
The best known families of which all species tested contain tannin are: Aceraceae, Actinidiaceae, Anacardiaceae, Bixaceae, Burseraceae, Combretaceae, Dipterocarpaceae, Ericaceae, Grossulariaceae, Myricaceae for dicot and Najadaceae and Typhaceae in Monocot. To the family of the oak, Fagaceae, 73% of the species tested (N = 22) contain tannin. For those of acacias, Mimosaceae, only 39% of the species tested (N = 28) contain tannin, among Solanaceae rate drops to 6% and 4% for the Asteraceae. Some families like the Boraginaceae, Cucurbitaceae, Papaveraceae contain no tannin-rich species.
The most abundant polyphenols are the condensed tannins, found in virtually all families of plants, and comprising up to 50% of the dry weight of leaves. Tannins of tropical woods tend to be of a cathetic nature rather than of the gallic type present in temperate woods. There may be a loss in the bio-availability of still other tannins in plants due to birds, pests, and other pathogens (Kadam et al., 1990).
In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of a hydroxylgroup bonded directly to an aromatic hydrocarbon group. The simplestof the class is phenol, which is also called carbolic acid C6H5OH. Phenolic compound are classified as simple phenols or polyphenols based on the number of phenol units in the molecule (Amorati and Valgimmigli, 2012; Robbins and Rebecca, 2003).
Phenol - the simplest of the phenols.
Quercetin, a typical flavonoid, is a polyphenol
Phenolic compounds are synthesized industrially; they also are produced by plants and microorganisms, with variation between and within species (Hattenschwiler, et al., 2000). Although similar to alcohols, phenols have unique properties and are not classified as alcohols (since the hydroxyl group is not bonded to a saturated carbon atom). They have higher acidities due to the aromatic ring's tight coupling with the oxygen and a relatively loose bond between the oxygen and hydrogen. The acidity of the hydroxyl group in phenols is commonly intermediate between that of aliphaticalcohols and carboxylic acids (their pKa is usually between 10 and 12).Loss of a positive hydrogen ion (H+) from the hydroxyl group of a phenol forms a corresponding negative phenolateion or phenoxideion, and the correspondingsalts are called phenolates or phenoxides, although the term aryloxides is preferred according to the IUPAC Gold Book. Phenols can have two or more hydroxy groups bonded to the aromatic ring(s) in the same molecule. The simplest examples are the three benzenediols, each having two hydroxy groups on a benzene ring.
Cannabinoids the active constituents of cannabis
Capsaicin the pungent compound of chili peppers
Carvacrol found in, i.a., oregano; antimicrobial and neuroprotectant
Cresol found in coal tar and creosote
Estradiol estrogen – hormones
Eugenol the main constituent of the essential oil of clove
Gallic acid found in galls
Guaiacol (2-methoxyphenol) - has a smokey flavor, and is found in roasted coffee,whisky, and smoke
Methyl salicylate the major constituent of the essential oil of wintergreen
Raspberry ketone a compound with an intense raspberry smell
Salicylic acid precursor compound to Aspirin (chemical synthesis is used in manufacturing)
Serotonin / dopamine / adrenaline /noradrenaline natural neurotransmitters
Thymol (2-Isopropyl-5-methyl phenol)-found in thyme; an antiseptic that is used inmouthwashes
Tyrosine an amino acid
Sesamol a naturally occurring compound found in sesame seeds
Phenol the parent compound, used as a disinfectant and for chemical synthesis
Bisphenol A and other bisphenols produced from ketones and phenol / cresol
BHT (butylated hydroxytoluene) - a fat-soluble antioxidant and food additive
4-Nonylphenol a breakdown product of detergents and nonoxynol-9
Orthophenyl phenol a fungicide used for waxing citrus fruits
Picric acid (trinitrophenol) - an explosive material
Phenolphthalein pH indicator
Xylenol used in antiseptics & disinfectants
DRUGS, PRESENT AND PAST
Diethylstilbestrol a synthetic estrogen with a stilbene structure; no longer marketed
L-DOPA a dopamine prodrug used to treat Parkinson's Disease
Propofol a short-acting intravenous anesthetic agent
Phenols are important raw materials and additives for industrial purposes in:
⦁ laboratory processes
⦁ chemical industry
⦁ chemical engineering processes
⦁ wood processing
⦁ plastics processing
Tannins are used in the tanning industry. Some natural phenols can be used as biopesticides. Some phenols are sold as dietary supplements. Phenols have been investigated as drugs. For instance, Crofelemer (USAN, trade name Fulyzaq) is a drug under development for the treatment of diarrhea associated with anti-HIV drugs. Additionally, derivatives have been made of phenolic compound, combretastatin A-4, an anticancer molecule, including nitrogen or halogens atoms to increase the efficacy of the treatment (Carr et al., 2010).
Notable sources of natural phenols in human nutrition include berries, tea, beer, oliveoil, chocolate or cocoa, coffee,pomegranates, popcorn, yerba maté, fruits and fruit based drinks (including cider, wine and vinegar) and vegetables. Herbsand spices, nuts (walnuts, peanut) and algae are also potentially significant for supplying certain natural phenols.Natural phenols can also be found in fatty matrices like olive oil. Cloudy olive oil has the higher levels of phenols, or polar phenols that form a complex phenol-protein complex.
Phenolic compounds, when used in beverages, such as prune juice, have been shown to be helpful in the color and sensory components, such as alleviating bitterness (Donovan et al., 1998).
Some advocates for organic farming claim that organically grown potatoes, oranges, and leaf vegetables have more phenolic compounds and these may provide antioxidant protection against heart disease and cancer (Asami et al., 2003). However evidence on substantial differences between organic food and conventional food is insufficient to make claims that organic food is safer or healthier than conventional food (Smith et al., 2012)..