Ginkgo biloba. Characteristics and botanical description
At the beginning of the XXI century the medical science achieved spectacular progresses related to the prevention and treatment of multiple pains, which derived in a greater life expectancy currently being between 75 and 78 years (average) in the developed countries.
However, this greater longevity is not always accompanied by a better life quality. In that sense, the treatments of chronic diseases in old patients have derived in a very important increase in the health social costs of these countries. Within this context, the brain circulatory diseases constitute one of the main causes of morbimortality, affecting essentially to old people, deriving in extended confinements, high expenses on medicine and setbacks for the family of being in situations which often are irreversible. Among the most frequent diagnosis derived of the deficits of brain circulation we find:
So, the question everybody asks is: Can these diagnoses be prevented? Undoubtedly, during our lives we add to our organisms, almost unconsciously, a set of elements that are not always beneficial nor well received by the body: excess of saturated fats in the alimentation, tobacco, alcohol, stress, being sedentary, etc.
The second question after this reading is: If we avoid these factors, do we avoid the brain circulatory diseases? A logical answer would indicate that they could be avoided in a big proportion. However, medicine is not a mathematical science and possibly other factors such as genetics, environmental pollution, weather factors, emotional problems and the extended intake of certain medicines could play an important role. Modern pharmacology, within its permanent search of drugs that relieve or improve the people’s quality life, has focused its struggle against the circulatory diseases in two different targets:
• the reinforcement of the arterial walls through the elimination of free radicals.
• the diminution of circulating fats and blocking of factors which activate platelets.
From the appearance of the traditional and “old remedies” for the brain circulation (xantinol nicotinate, vincamine, cinarizine, flunarizine), passing through the new calcium antagonist agents (nimodipine, nicardipine amlodipine, etc), a complete and integrating treatment on the different causes that originate deficits of brain circulation could not be adjusted. Even the side effects of some of these drugs (cardio depression in the case of calcium antagonists, or gastralgias in the case of flunarizine) have limited its use, without observing a cost/benefit that bends the scale in favor of its use.
However, what the modern science and the pharmaco technology could not solve properly, nature, which surprises us pleasantly year after year, seems to have a better answer. In effect, there exists an antique tree that has survived from every catastrophe on earth and that for the last 20 years it has been studied exhaustively on this field. We are referring to: GINKGO BILOBA.
We propose to have a look at different topics which will give us thorough data on the potential activity of this millenary specie which is considered to be the best answer to the deficits of brain vascular irrigation.
• SCIENTIFIC NAME
Ginkgo biloba L.
Synonym: Salisburia adiantifolia Smith.
• POPULAR NAMES Spanish: ginkgo, tree of the 40 shields. Portuguese: ginkgo English: ginkgo, maindenhair tree. Others: ginkgo (French), ginco (Italian), Echter Ginkgobaum (German).
• BOTANICAL DESCRIPTION
It is a dioecious tree, of the Ginkgoacea family; it has a slow growth (15 cm the first year, 30 cm the second one, reaching its normal height (13-17 meters tall) in the third or fourth decade. The leaves have a bilobulade shape and are greenish, becoming bright yellow in autumn; they fall almost all together during that season. The fruit has a fleshy appearance and it is yellow-greenish, when it falls it emanates an unpleasant odor.
• HABITAT
Ginkgo biloba is Asian (China, Korea, Japan) being the only representative of the Ginkgoacea family, that’s why its botanical classification was always difficult, being an intermediate type between Pteriodofites (ferns) and Conipheres. Except in the mountain regions of the eastern China, this tree is not practically cultivated.
• HISTORY
According to the fossil remains found in Iran and Spain which were 220 and 150 millions of years old respectively, the existence of Ginkgo biloba on the planet dated from the Jurassic period. In the oldest book of medicine that is known (Pents'ao), the Chinese Emperor Shen Nun already referred to its tonic kindnesses for the heart and lungs. The Chinese Buddhish monks adopted it as sacred tree. Due to its therapeutic properties conferred to its leaves, in the Far East it was used as coin of interchange among salesmen.
The term Ginkgo derives from the Chinese Yin-kuo = "golden damask". The name of “tree of the forty shields” was due to the intense yellow coloration that its top has in autumn. Whereas the specie name of biloba refers to the bilobulade appearance of its leaves. Several are the versions on how this tree arrives in Europe, but most of them indicate the English explorer Engelbert Campfer as the one who introduced it in the XVII century. As it does not look alike any other tree, the European botanic men had many difficulties in classifying it. At the beginning, the first seeds received were used to get samples for ornament purposes. In 1964 the Schwabe Laboratory from Germany developed the first standardized extract (EGb 761) which gave origin to many clinical studies.
• PART USED
The vegetal drug is constituted by the leaves. They are collected at the beginning of the autumn, when they present a yellowish color. The seeds and fruits are only used in Chinese medicine. The organoleptic characteristics indicate little odor and slightly bitter flavor.
• MACROSCOPICAL CHARACTERISTICS
The leaf of ginkgo may have several shapes, it can be divided, bilobulade (the most frequent one) or almost complete. The stem has two lines of conductor tissue that are divided on the upper part and also on the limbus, according to the dichotomous way, giving a striated appearance (on both sides) with a fan appearance.
• MICROSCOPICAL CHARACTERISTICS
The structure organization of the foliar lamina has an adaxial face that with a frontal view it has cells with rectangular shape with sinuous anticlinale walls, being the sinuosity more intense in longitudinal sense. In the transversal section they are papillary. As regards the abaxial face, with a frontal view the cells have variable shapes, being only some of them rectangular. The anticlinale walls are sinuous and the external periclinal wall has prominences (papillas). There are stomas, characterizing the leaf as hypostomatic.
The limbus has an epidermis stratum on both sides. The mesophile is filled with chlorophylian parenchyma, with ducts or channels and idioblasts with druses. The stem in the transversal section of the medium region has an adaxial and a convex abaxial face. Inside the epidermis, there are sclerenchimatic cells. The vascular lines are surrounded by sclerenchime cells. There are ducts or channels and idioblasts with druses, some of them with mucilages.
• CHEMICAL COMPOSITION
Leaves have:
FlavonolicGlucosides (0,5-1%): Almost 40 of the structures have been identified on the leaves, including the ones derived from epicatecol (epicatechin, epigalocatechin), dehydrocatechins (proantocianidins, prodelphinidins), flavones (luteolin, delphidenon = tricetin, etc) and biflavones. Biflavones are composed by two structures of flavone cycle linked between each other, highlighting: ginkgetine (the most important one), isoginkgetine, amentoflavone, sciadopitisin and bilobetin. Flavonols are present like aglicones or like mono-, di-, or triglycosides, being in some cases sterificated with cumaric acid.
Terpenes: of diterpenic type there are: ginkgolides A, B, C, J y M (the latter only in the root) and of sesquiterpenic type represented by bilobalides. The ginkgolides present on the leaves of this tree (0-0.50%) have not been found in any other vegetal specie, differentiating among them only in the number and position of the hydroxile groups. The quantity of bilobalides on the leaves varies between 0.005- 0.40%. Ginkgolides and bilobalides are found in smaller quantities in the root of the tree.
Seeds contain a 38% of carbohydrates, 4.3% of proteins and 1.7% of fats.
a) Qualitative determination of flavonoids:
PIt can be performed by the classical method (described in several pharmacopeias) of hydrolysis of glucosides and its after detection by spectrophotometry, giving a complex chelate of aluminum chloride. It is not a very specific method and it gives only an approximate estimate of the total of flavonoids in the plant. With this method a quail quantitative determination of aglycons is not possible. In the case of G. biloba, the method is not reproducible due to the big quantity of proanthocyanidines that alter the result. On the other hand, it constitutes a method of selective analysis of ginkgo flavonoids, the high resolution of liquid chromatography on the reserve face and alter the diode - array detection.
b) Qualitative determination of terpenes:
The low concentration of terpene lactones on the powder of the leaves makes it difficult to identify them. These substances have a weak ultraviolet spectrum and they must be extracted through a highly complex matrix. There is a chromatography on thin layer described on the BHP and on the book written by Wagner & Blat edited in 1996.
a) Quantitative determination of flavonoids: There are few methods described for that purpose. Some authors support the quantification of biflavones through the high resolution of liquid chromatography (CLAR); on the other hand, others describe three methods of selective analysis with CLAR, to determine flavonoids on the powder, extracts and phytomedicines. In this sense, they elaborate a CLAR method from the hydrolysis of flavonoid glucosides (which are abundant in the vegetal drug). It is a simple, rapid and reproducible method to quantify the 3 aglycons: kaempferol, quercetina and isoramnetina. The work procedure consists of 2 stages: hydrolysis and glucoside extraction and preparation of the sample. The flavonoid aglycons are analyzed by CLAR in the reverse phase using a methanol water gradient with 0.5% v/v of orthophosphoric acid and UV detection at 370 nm.
b) Quantitative determination of terpenes: By means of the selective extraction of terpene lactones from the powder of the plant with methanol and water (10:90) or of phytomedicines with water, analyzing through CLAR in the reverse phase with water-methanol (67:33) like mobile phase and after infrared detection.
