Chemical compositions of the essential oil and calculation the biophysicochemical coefficients of the components of Hymenocrater longiflorus Benth . of Iran

The volatile constituents of the essential oil of Hymenocrater longiflorus Benth. growing wild in Kurdistan-Iran were investigated using the GC and GC/MS techniques. Fifteen compounds, representing twenty (97.03%) of the total oil were identified. The main components were: αPinene (22.47%), β-Caryophyllene (18.05%), βEudesmol (14.92%), α-Copaene (9.84%), γ-Elemene (6.79%), δ-Cadine-ne (6.13%), (–)Bornyl acetate (5.61%), α-Amorphene (3.84%), α-Fenchyl acetate (2.35%) and β-Pinene (2.07%). Some of the physicochemical properties like the logarithm of calculated Octanol-Water partitioning coefficients (log Kow), total biodegradation and (TBd in mol/h and gr./h), water solubility (Sw, mg.L at 25oC) and median lethal concentration 50 (LC50) were calculated for the 15 components of Hymenocrater longiflorus Benth.


INTRODUCTION
Hymenocrater genus has over 21 species in the world.[1,2] The Hymenocrater longiflorus Benth.materials of this study were collected from west of Iran (from the mountains area, altitude 1550-1800 m, in front of the Dezlie village-Marivan-Kurdistan province of Iran) at the Jun.2008.A voucher specicum has been deposited in herbarium of Research Center of Agriculture & Natural Resources, Sanandaj-Kurdistan, Iran (Herbarium ID: 447898-1).
This herb was firstly nominated by G. Bentham in 1848.The local name of Hymenocrater longiflorus Benth., is Soor-Halale (Sỏỏr-HΛLΛLΕ).The other names of this herb are: Gole Arvaneh-Avarmani and SoorSanduo.The Hymenocrater longiflorus Benth.was utilized as a medicinal herb in local and traditional medicine (in Kurdistan).From the aerial parts of this herb in crude or baked form was utilized as an anti-inflammatory, sedative, anti-skin allergic reaction (for skin diseases and insect bite) by folks in local medicine.
The octanol-water partition coefficient (K ow ) is a measure of the equilibrium concentration of a compound between octanol and water that indicates the potential for partitioning in to soil organic matter (i.e., a high K ow indicates a compound which will preferentially partition into soil organic matter rather than water).This coefficient is inversely related to the solubility of a compound in water.The log K ow is used in models to estimate plant and soil invertebrate bioaccumulation factors.This parameter is also used in many environmental studies to help determine the environmental fate of chemicals [3][4][5].
Biodegradation is usually quantified by incubating a chemical compound in presence of a degrader, and measuring some factors like oxygen or production of CO 2 .The biodegradation studies demonstrate that microbial biosensors are a viable alternative means of reporting on potential biotransformation.However, a few chemicals are tested and large data sets for different chemicals need for quantitative structural relationship studies [6].
An LC 50 value is the concentration of a material in air that will kill 50% of the test subjects (animals, typically mice or rats) when administered as a single exposure (typically 1 or 4 hours).Also called the median lethal concentration and lethal concentration 50, this value gives an idea of the relative acute toxicity of an in halable material.Typical units for LC 50 values are parts per million (ppm) of material in air, μg (micrograms, 10 -6 gram) per liter of air and milligrams (10 -3 gram) per cubic meter of air [7].

ANALYTICAL METHODS
Dried aerial parts of Hymenocrater longiflorus Benth.were subjected to hydrodistillation for 5 hours using Clevenger-type apparatus to produce a yellow oil in 0.28% (w/w) yield.The essential oil of the aerial parts of Hymenocrater longiflorus Benth.was examined by GC/MS (GC: HP 6890, MS: HP 5973), column (HP5-MS, 30 m  0.25 mm fused silica capillary column, film thickness 0.32 m) by temperature program 60C (3 min)-210C (2 min) at the rate of 6C/min (injection temperature 250C, carrier gas: helium (with purity 99.999%), detector temperature 150C, ionization energy in mass was 70 eV, mass range 10-300 amu, and scan time was 1 sec.
The calculated data of the Octanol-Water partitioning coefficients (log K ow ) and the total biodegradation TB d (in mol/h and gr/h), water solubility (S w , mg.L -1 at 25ºC) and median lethal concentration 50 (LC 50 ) were calculated by the EPI-suit v4.00 package [11].

DISCUSSION
Some of the plants from genus Hymenocrater have been previously studied, but there are rare studies of the chemical composition of essential oil of plants from genus Hymenocrater.This study elaborates upon the volatile constituents of the essential oil of Hymenocrater longiflorus Benth.growing wild in Kurdistan-Iran were investigated by GC and GC/MS technique.As could see in Table 1, α-Pinene (22.47%), β-Caryophyllene (18.05%) (trans-Caryophyllene) and β-Eudesmol (14.92%) have the high percentages (about 55.44%) among the fifteen components that were identified.Some other components, i.e. α-Copaene (9.84%), γ-Elemene (6.79%), δ- α-Pinene has the highest percentage (22.47%) in this herb.α-Pinene, is a natural bicyclic sesquiterpene that is a constituent of many essential oils.α-Pinene and β-Pinene.As the name suggests, both forms are important constituents of pine resin; they are also found in the resins of many other conifers, and more widely in other plants.Both are also used by many insects in their chemical communication system.α-Pinene and β-pinene are both produced from geranyl pyrophosphate, via cyclisation of linaloyl pyrophosphate followed by loss of a proton from the carbocation equivalent [12].
β-Pinene with 12.06% in this herb was utilized as an intermediate for perfumes and flavorings.It also occurs naturally in rosemary, parsley, dill, basil, yarrow, and rose.α-Pinene with 9.94% in this herb was utilized as solvent for protective coatings, polishes and waxes, synthesis of camphene, comphor, geraniol, terpin hydrate, terpineol, synthetic pine oil, terpene esters and ethers, lube oil additives, flavoring and odorant.It is also found in the essential oil of rosemary (Rosmarinus officinalis).
β-Caryophyllene or trans-Caryophyllene is one of the chemical compounds that contribute to the spiciness of black pepper.β-Caryophyllene, is a natural bicyclic sesquiterpene that is a constituent of many essential oils, especially clove oil, the oil from the stems and flowers of Syzygium aromaticum (cloves), the essential oil of hemp Cannabis sativa, and rosemary Rosmarinus oficinalis.It is usually found as a mixture with isocaryophyllene and α-humulene, a ring-opened isomer.Caryophyllene is notable for having a cyclobutane ring, a rarity in nature [12,13].
It was found that β-eudesmol, a sesquiterpenol constituent of Chinese herb antagonized organophosphateinduced lethal toxicity by reversing the neuromuscular failure and reducing the occurrence of convulsions [13].
Its possible antiepileptic action was further explored in electroshock seizure mice in vivo and in high potassium treated rat hippocampal slices in vitro.At a dose with little effect on the motor activity, β-eudesmol pre-vented the convulsions and lethality induced by maximal electroshock but not those by pentylenetetrazol or picrotoxin.At sub effective doses, β-eudesmol and phenytoin showed additive effect in preventing electroshock seizures.Extracellular recording of field potentials in CA1 pyramidal layer of hippocampal slices showed that β-eudesmol reduced the high potassium (8.5 μM)-induced electrographic seizure activity.The potential of β-eudesmol to serve as an antiepileptic or a conjuvant in phenytoin therapy is suggested [14].
α-Copaene, a potent attractant for male Mediterranean fruit flies.Ceratitis capitata is found as a minor component in the essential oils of various plant species, including its hosts such as orange, guava, and mango.Despite the specific attraction of male flies and the wide distribution of the compound in host plants, the biological significance of α-copaene remains unknown [15].Chemically, the copaenes are tricyclic sesquiterpenes.The molecules are chiral, and the α-copaene enantiomer most commonly found in higher plants exhibits a negative optical rotation of about −6°.The rare (+) -α-copaene is also found in small amounts in some plants.It is of economic significance because it is strongly attracting to an agricultural pest, the Mediterranean fruit fly Ceratitis capitata [15].Bornyl acetate is a constituent of some essential oils.It has been used in aromatic preparations in the treatment of coughs.
Chemically, the cadinenes are bicyclic sesquiterpenes.The term "cadinene" has sometimes been used in a broad sense to refer to any sesquiterpene with the socalled cadalane (4-isopropyl-1, 6-dimethyldecahydronaphthalene) carbon skeleton.Because of the large number of known double-bond and stereochemical isomers, this class of compounds has been subdivided into four subclasses based on the relative stereochemistry at the isopropyl group and the two bridgehead carbon atoms.[13][14][15].
It is reported and accepted that the toxicity property of organic compounds can be predicted on the basis of the log K ow [7].Total biodegradation (TB d ) is another useful and important factors in chemical and biochemical studies [33].The LC 50 value is called the median lethal concentration and lethal concentration 50, this value gives an idea of the relative acute toxicity of an in halable material.One of the other important physicochemical factors of compounds is water solubility (S w , mg.L -1 at 25ºC).In accordance with the calculated data of the components 1-15 (see Table 1) γ-Elemene, Germacrene-D and α-Humulene have the highest log K ow , among the components 1-15 (7.09, 6.99 and 6.95, respectively).α-Humulene and α-Copaene have the lowest water solubility (S w , mg.L -1 at 25ºC).β-Caryophyllene has the highest LC 50 (mg/L) and γ-Elemene, Germacrene-D and α-Humulene are three components with lowest LC 50 (0.005, 0.006 and 0.013, respectively).The total biodegradation (TB d ) of β-Eudesmol among 1-15 is the highest and for β-Pinene is the lowest amount (in mol/h and gr/h).The total biodegradation (TB d ) for α-Pinene (22.47%)(The highest percentage component) is calculated: 7.70 (mol/h) and 1.05 (gr/h).In Table 1, the values in parentheses are the experimental values for logarithm of Octanol-Water partitioning coefficients (log K ow ).The other values were calculated by the EPI-suit v 4.00 package.For the other items there were not available values from data base [11].
Perhaps, the high densities of the main compounds give some biological activities to the essential oil or to this herb.Although no records of toxicity have been found for this plant, it belongs to a family that includes many poisonous plants so some caution is advised [34,35].