Olive tree
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Italian olive tree: an extraordinary font of precious raw material for cosmetic applications.

The strong demand for cosmetic products containing traditional olive derivatives is due to the emollient, softening, anti-reddening, sebum restructuring and photo-protective properties of the oil and the anti-radical – anti-ageing properties of the phyto-complexes extracted from the leaves. An analysis of thecharacteristics of some new derivatives opens vast new potential areas of application that puts this plant of great traditions back into the lime light for its recently discovered phyto-cosmetic values.

The History

The olive is one of the most ancient cultivated fruit trees known to man and its importance to the ancient Mediterranean civilisation is testified in many classic sources. The olive is so typical to the Mediterranean that its presence in a cultivated form creates a Mediterranean environment even in other parts of the world. The name olea is derived from the Greek elaia=oil and alone explains the importance of the species.

The earliest evidence of the cultivation of olives for oil can be traced to 4000 BC and beyond (Zohary and Spiegel-Roy, 1975). The area of cultivation is generally the coasts and islands of the eastern Mediterranean even though it is believed that the ancestors of today’s variety of oils originated from the mountainous territories south of Caucaso, which includes modern day eastern Turkey, western Iran, Lebanon, northern Israel, Syria and northern Iraq (Acerbo, 1937; Zohary, 1973). The first records can be found in Genesis when, at the end of the deluge, a dove sent by Noah to look for land returns with an olive branch in its beak. For the Jews, the olive was a precious gift from God, a symbol of alliance. Olive oil was used for the consecration; “Messia” in Hebrew (kuristés in Greek) means the anointed.

The olive spread from the western Mediterranean towards the west in Greece and theAegean archipelago. In this area, considered a secondary centre of diversification, the olive grew in importance and probably became a choice crop for man between 3000 and 2000 BC. In the palace of Crasso in Crete there was an impressive warehouse of oil jars that could carry five times the total requirement of the island, a quantity that highlights the fact that at that time, not only the production of olive oil was extremely developed, but also the trade of the oil (Boardman, 1977). According to the legend, the olive was planted for the very first time by the Goddess Athena in Attica on the acropolis of Athens. For this reason the Hellenic culture considered the olive trees to be sacred and burning or damaging them was strictly prohibited.

In fact, during the ransacking of Athens, the Spartans spared the olive trees, fearing a divine revenge. Towards the beginning of 1000 BC a new migration of the olive began, again towards the west, in the direction of Sicily-Calabria and Tunisia. From here, during IV century BC, probably passing through Etruria (Boardman, 1977), the olive arrived in Rome (Acerbo, 1937; Simmonds, 1976). Up to this moment, the olive had moved towards the west very slowly, first transported in the merchant vessels of the Fenians and then by those of the Greeks.  These populations spread the species into many Mediterranean areas, including Spain, southern France and North Africa, but with uncertain results.

The Roman Legions conquer of every territory boarding on the Mediterranean and their subsequent transformation into avast and united empire gave way to improved communication and more intense and safe commerce.

The olive benefited from this situation as the Romans spread its cultivation into many new areas, including Spain, Dalmazia and Provenza.

As in Hebrewism, the olive became a symbol of peace within the Christiantradition. In Christian liturgy, sacred olive oil is used in the sacrament of Baptism, in confirmation, in ordination and the Extreme Unction. After the fall of the Roman Empire, historical information about the olive became rare and its culture lost its interest. However, the olive continued to be popular in Arab dominated territories to the point that in occupied Sicily the cultivation was forbidden so that the economy of North Africa, at this point the principle area of cultivation, would not be damaged.

For Islam the olive is the cosmic tree, the centre and pillar of the world, a blessed tree and source of light thanks to the oil it produces. The consumption of the oil continued to be limited in Europe and eventually regained some importance only in the XVI-XVII centuries when it once more became an important merchandise for the Venetians who imported it into Europe from their estates in the Aegean (Cyprus, Crete, Corfů). The olive oil was not only used as a food, but also as a fuel for illumination, as a raw material for the production of soap, ointments and creams for the treatment of the face and body. In classic Greek medicine, olive oil was used as a remedy for many pathologies, for friction in massages and as a carrier for other medicines (Penso, 1986). The same thing occurred in Arab medicine and in the medicine of the Mediterranean countries of the middle ages, that used the leaves of the olive for their astringent, tonifying and febrifugal properties (Benigni et al., 1963).

Botany

The olive Olea europaea L. belongs to the family of the Oleaceae, which includes vegetable species from just about every region of the world with a temperate or tropical climate (from Africa to New Zealand).  These species are arboreal or shrubby, and sometimes climbing.

Fraximus (Ash)

Jasminum (Jasmine)

Ligustrum (Privet)

Phillyrea (Fillirea)

Syringa (Lilac)

Olea (Olive)

Within the Olea family there are thirty-five species, the most important being the Olea europaea which is divided into two subspecies:

ˇ      Olea Europaea subspecies europaea (also var. Sativa) which is a cultivated species.

ˇ      Olea Europaea subspecies sylvestris  which is a wild species common to the southern Mediterranean coasts.

Cultivated olive trees are evergreen and grow very slowly to roughly 50 ft. In height and 30 ft. In spread. Its leaves grow opposite one another to 70-80mm in length and 10-20mm in width. They are placed in groups of twos and threes and are hard/thick. They are darker green on top and silver, grey green underneath and are covered in thick layer of plural-cellular hairs; they are star-shaped and have an evident midrib.  The flowers are grouped in small twigs and are white in colour. The flowers are small, fragrant, cream-coloured and largely hidden by the evergreen leaves. They are funnel shaped and frail and grow on a long stem arising from the leaf axils. The fruit (olive) is a green drupe of 10-35 min in length and weighing from 1 to 6-7 g), it is oval, ellipsoid or spherical, violet black or reddish in colour, shinny and smooth and sometimes pruinose.

If the olives not harvested, the flowers and fruits may be present contemporaneously.

Even though the olive is considered a tree, it has a bushy vegetative form. The buds closest to the trunk open more easily and the growth around the base of the plant of a thick formation of sprouts, makes the plant look more wild and bushy in appearance.

The mignolatura occurs in variable moments from one year to the next according to the cultivation environment; generally between the end of March and the beginning of June, 4-5 weeks before full flowering. The overlapping of the differentiation cycle between flowering and fructification makes the alternation of production very common and therefore there is an alternation of a fruitful year followed by a less fruitful year.

A further characteristic of the floral biology of the olive is its auto-incompatibility, or auto-sterility, that imposes a sufficient cross fertilisation in the olives. Even if some varieties, like the ‘Frantoio’ are sufficiently auto-fertile, association is always preferable.

                

These images show the under side of an olive leaf under a scansion electronic microscope (SEM). In the first photograph the star hairs can clearly be seen, while in the second we can see the stomatic openings that appear once the star tricomes are removed.

Cultural techniques

The olive is prevalently a Mediterranean species and therefore not adapt for very cold climates, especially where cold spells may occur in very late spring. It can, however, support very low temperatures (–10°/-12°C) if they occur gradually and during wintertime. The olive does not require great amounts of water, even though irrigation may be useful in periods of drought. The soil does not need to have any particular characteristics, not even regarding its pH. The olive should not be placed near stagnant water and when the area has clay type soil it should be suitably prepared. Planting is performed by grafting seedlings into a nursery or con barbatelle propagate in nebulisation (the micropropagation is not popular for this species). As with other fruit trees, the distance between trees has gradually decreased to 4.5 – 5 metresin the row and 5 – 7 metres between the rows. The forms of plant breeding are numerous, but the most common are the vase, in the case of hand picking, and mono-cone when mechanical harvesting is planned. Pruning is usually performed annually, althoughsometimes intervals between pruning can extend to 2 or more years.

Phytochemistry

The oil is extracted by pressing the olives, which contain between 15 and 30% of oil. From a chemical point of view, the oil is a fatty substance that contains, principally in the form of triglycerides, oleic acid, linoleic acid, palmitic acid and modest quantities of stearic acid. The following is the typical composition of olive oil:

Palmitic: C16: 0 5.0 – 12.0
Palmitoleic: C16: 1 1.0 max.
Stearic: C18 : 0 3.5 max.
Oleic: C18 : 1 65.0 – 80.0
Linoleic: C18 : 2 6.0 – 25.0
Linolenic: C18 : 3 1.0 max.
Arachidic: C20 : 0 0.6 max.
Gadoleic: C20 : 1 0.5 max.
Beenic: C22 : 0 0.3 max.
Erucic: C22 : 1 0.2 max.

A small part of the fatty acids, present in the form of free acids rather than triglycerides, is responsible for the typical ‘acidity’ of the oil. At 20°C, the oil has a density of 0,910 - 0,916, a refraction index of 1,460 - 1,470, a saponification index of 184 - 196, a number of iodine between 80 – 95 and an unsaponifiablepercentage (in petrolium ethers) of around 1,5%.

The unsaponifiable part isformed of hydrocarbons, wax, sterols, terpenic alcohol and aliphatics, colorants, tocopherols and vitamins. Some of these components, even though present in tiny concentrations, play an important biological role as antioxidants (tocopherols) or because they permit the identification of the origin and genuineness of the oil, or theabsence of rectification treatment.

The chemical composition of theunsaponifiable part is very different to the olive oil itself: the density at 20°C is 0,850 – 0,870, the saponification index is max. 5 and the iodine index is 320 – 375.

In the unsaponifiable matter, 5 different chemical classes are present, listed in their polarity sequence as follows:

Unsaponifiable hydrocarbons:

85.0– 65.0%

Hardly saponifiable aldehydes and esters:

  5.0– 10.0%

Linear and triterpenic alcohols:

  5.0– 12.0%

Phytosterols:

  4.0– 10.0%

Unidentified components:

  1.0–   3.0%

The unsaponifiable from olive oil finds its primary and basic use in topical products due to its emollient, softening and sebum restorative properties. The product is therefore particularly suitable for the treatment of dry, alipoidic and dehydrated skin. These characteristics are particularly interesting in cases of delicate and sensitive skin, like children’s skin. The products photo protective action is also well known, and it is therefore widely used in sunscreen products. Also, the decongestive and re-epithelizing action of the unsaponifiable products on burns (actinic burns included) means that they can be exploited in dermo-pharmaceutical preparations for the treatment of scalds. This characteristic also makes them interesting for use in the cosmetic field of “after-sun” products.

The conditioning, substantiating and over fattening effect of unsaponifiable matters makes them excellent for use in hair balsams, rinsing creams, soaps, syndets and foaming creams. A particularly interesting application in gum toothpaste was discovered following investigations carried out in the stomatological field.

Make-up products can also be improved with the use of olive oil unsaponifiable; in lipsticks, make-up bases, crayons and as a binder in powders and eye shadows. It must be remembered that due to the typical emulsifying property of triterpenic alcohols, the unsaponifiable derivatives lower the emulsion interfacial tension, thus making them more stable and homogeneous.

Properties

Seed oils, obtained through the pressing or extraction with solventsfrom the fruit seeds of many plants, are primarily formed of triglycerides of fatty acids with one or more double links (oleic, linoleic etc.), which have a melting point that is notably lower than the substances that mainly contain saturated fatty acid triglycerides which is the case with fats and animal derived oils. In the acidic composition the seed oil has a prevalence of polyunsaturated fatty acids compared to the olive oil. This fact must be carefully considered according to the intended use of the oil.

Considering that from a caloric point of view, all fats are equivalent, contributing an energetic value of 9.4 cal/g to the metabolism (lighter oils, therefore, do not exist), the nutritive value of an oil is determined by some factors related to the stability towards the oxidising process and the presence of some minor constituents of notable biological value.

When the seed oil, which is rich in the triglycerides of linoleic and linolenic acids, is left in the open in thin layers, it suffers oxidisation and polymerisation. If they are to be used for frying, the extreme increase in temperature facilitates the start of oxidation processes.

The process of rectification that oils undergo, causes the prevalence of polyunsaturated acids and consequently, the elimination of the tocopherols capable of antioxidant actions contained in the unsaponifiable part.  On the contrary, virgin olive oil extracted exclusively with physical methods, maintains the initial characteristics of the fruit, with its biochemical properties intact and with a balanced chemical composition that makes it more resistant to the oxidation processes initiated by heat.

Olive Oil is described in all the main Pharmacopoeia (BP, DAB, FUI, PH. EUR., PH. FR., PH. GIAPP.), where its properties as an emollient, as a skin soothing agent, and treatment for eczema and psoriasis are mentioned. It is also used as an emollient and lubricant in the preparation of creams and as a carrier for oily suspensions for injection.  Considering its beneficial effects on the cardiovascular system, it is also recommended in diets.

A very careful review of the chemistry of the olive leaf was carried out in the ‘60’s by Italian Authors (Benigni et al., 1963) and the main elements identified were:

Oleuropeina, a bitter substance of β-glucosidic structure. Quantities of 1.5 to 2% were extracted from fresh leaves (Panizzi et al., 1958), from green olives harvested in summertime, from the trunks and the roots. According to Shasha and Leibowitz (1961) the oleuropein is a double ester of glucose with protocatechic acid and oleuropeic acid, C10H16O3 (acid 1-ossimetil-2, 6-dimetilacloes-2-en-carbonico-1).

Elenolide, an unsaturated milk C11H12O5, obtained by distilling under vacuum the components present in olive leaf extract.

Il N-pentatriacontano.

Oleanolic acid C30H48O3 at around 2% - 3%;

Omo-oleastranol C27H46O2, a neutral substance of triterpenic structure.

A chinone vitamin K2-similar with isoprenoide lateral chain.

Malic, tartaric, glycolic and lactic acids.

Two glucosides, oleoside and steroleoside.

Some enzymes: lipasi, perossidasi and emulsina.

Colina (absent in fresh leaves according to Panizzi et. al. (1960)).

The tannin pirogallic.

Glucose

Saccarosio

Mannitol

Essential oil.

The authors also highlighted the presence of anti-oxidant substances of a chemical nature that were not identifiable at that time.

They were later divided into five groups of fenolic compounds by Benavente-Garcěa (1999):

1)     Oleuropeosidi (oleuropeina and verbascoside).

2)    Flavons (luteolin-7-glucoside, apigenin-7-glucoside, diosmetin-7-glucoside, luteolina and diosmetina)

3)     Flavonols (rutina).

4)     Flavan-3-oli (catechina)

5)     Substituted phenols (tyrosolo, idrossityrosolo, vanillin, vanillic acid, and caffeic acid).

Of the anti-oxidant substances the oleuropeina is the most abundant, followed by the idrossityrosolo, flavon-7-glucosidi di luteolina, apigenina and  verbascoside. The idrossityrosolo is a forerunner of the oleuropeina and the verbascoside is a gucoside united with idrossityrosolo and caffeic acid. When mixed, the fenolic compounds of the olive leaves have a synergistic behaviour in their capability of ‘radical scavenging’. The sequence of the respective ‘radical scavenging’ capacity is rutina > catechina @ luteolina > leaf oil (extract) @ idrossityrosolo > diosmetina > caffeic acid > verbascoside > oleuropeina > luteolin-7-glucoside @ vanillic acid @ diosmetin-7-glucoside > apigenin-7-glucoside >tyrosolo > vanillina

The most active flavonoides (rutina, catechina and luteolina) have an anti-oxidant activity that is 2.5 times greater than lycopene and of vitamin C and E. It is interesting to note that the leaves alone offer an anti-oxidant activity that is greater than that of vitamin C and E thanks to the synergy between flavonoids, oleuropeosides and substituted fenols.

The synergistic behaviour of these compounds artificially mixed together is similar to that shown by the extract from olive leaves with a high oleuropeina content. The following table (Hänsel et al.,1993) gives a good overall view about the compounds extracted from olive leaves:

Apolar substances of various types: Fatty acids (C16 – C30), alcani (C21 – C35).  Long chain alcohols and aldeidi (C28 – C34).
Triterpenes: Oleanoic acid, betulinic acid, α and β amirina, uvaol and eritrodiol.
Terpenoids, iridioids: Oleuropein, oleurosid, ligstrosid, Oleoside 7, 11-dimentylester.
Fenolics, fenolic acids: Clorogenic acid, trans-cinnamic, paraidrossi-benzoic, trans-para-cumaric, protocateic, ferulic and caffeic. Acid
Fenolics, fenilpropanoids: Verbascoside
Fenolics, flavonoids: Flavonoids (derived from apigenin, luteolin, crisoeriol and quercetin).
Other fenolics: 3.4 diidroxy-b-phenylethanol (detto anche idroxytyrosol, created by oleuropein degradation).

 

Rossi (1996) recently published a re-classification of the biochemicalprofile of olive leaves.

1.     Secoiridoidi (4 –7%): oleosid, oleosid-11-metylether, ligstroside, excelsioside, ligustaloside β, morroniside, oleaceina.

2.     Triterpeni (2-4%): glucosides of oleanolic acid, maslinic acid and eritrodiol.

3.     Lignani:  (-)-ovivyl-4’-glucoside, (+)-acetoxypinoresinol and derivatives, cicloolivile

4.     Flavonoids: luteolin-4’-glucoside, luteolin, olivin, rutin, apigenin and derivativs.

5.     Alkaloids: cinconidina, cinconina.

6.     Sesquiterpeni: aromadendrene, eudesmina.

7.     Chinoni: tannins, polyphenolic acids

Pharmacology (therapeutical use)

Balansard and Delphaut (1953) attribute the oleuropeina with an immediate hypotensive action and the glycolic acid with a hepatorenal purifying action (diuretic and choleretic). They also acknowledge that the oleuropeina has a slight hypoglycemic action, an effect caused by the presence of polyunsaturated fats (acid α-linolenic) in the leaves that reduce the LDL cholesterol and increase the HDL.

Kasak and Stern (1962) find that the aqueous extract of olive leaves does not modify the metabolism of  Na and K and reduces the quantity of copper in the brain, liver and serum. They concentrated their attention on the effects of copper on the metabolism, studying the correlation existing between the oxidising enzymes contained in copper and the catecolamine (adrenaline and noradrenaline). They found that the hypotensive action of the oleuropeina is caused by the decrease of the copper content in the organism that occurs when the activity of the mentioned enzymes is inhibited and consequently the biosynthesis of the catecolamine is reduced.

Antioxidant effects

The flavonoids, fenols and oleuropeosidi have a marked antioxidant effect against free radicals (Bors et al., 1990; Visioli et al., 1998/a; Visioli et al., 1998/b). The formation of these radicals is connected to the normal aerobic metabolism of the cells; the consumption of oxygen innate during the growth of cells causes the production of numerous free radicals of oxygen. The interruption with molecules of a lipidic nature produces new radicals called superoxides, peroxides, hydroxilic and lipoides that can interact with the biological systems in a clearly citotoxic manner

Other effects

Another important property of the olive leaf is that of it anti-microbial action against viruses, retroviruses, bacteria, yeast, fungus, moulds and other parasites (Aziz et al., 1998; Juvene Henys, 1972; Koutsoumans et al., 1998; Tassou and Nychas, 1995). Other effects attributed to the oleuropeina are the strengthening of cellular protection and internal organism through the fast replay of macrophages (Visioli et.al 1998-b).

Conclusion

The olive has been part of the history of medicine, herbalist medicine and Mediterranean cosmetics for thousands of years and every civilisation has not only used it for the production of oil to be used for food and for illumination, but also as a medicinal plant. The olive oil has always been used as a fundamental ingredient for herbalist and cosmetic preparations as well as being an extremely popular medication. When examining the anti-oxidant and anti-microbial properties in depth, vast potential uses for plant and its herbal preparations become apparent. The olive is the pillar of the economies of the Mediterranean countries and has an important role not only in the food sector, but also in the cosmetic and herbalist sectors.


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