hereinafter , the present invention will be described in detail with reference to examples . it is to be understood , however , that these examples are for illustrative purposes only and are not to be construed to limit the scope of the present invention . a ground ginkgo biloba bark was extracted with methanol to obtain a crude extract of the bark . the crude extract was subjected to solvent fractionation to obtain a methylene chloride soluble portion ( gbd ). the methylene chloride soluble portion was fractionated by sephadex column chromatography ( meoh : etoh = 1 : 1 ) to obtain 50 ml of each of 90 fractions . each of these fractions was developed by thin layer chromatography ( tlc ; silica gel 60 f 254 ) using a mixture of toluene : ethyl formate : formic acid = 5 : 4 : 1 ( v / v / v ) as a developing solvent , was visualized with a uv lamp ( 254 nm ) and separated into five fractions ( gbd - 1 to gbd - 5 ). among said five fractions , the gbd - 2 fraction was fractionated by sephadex column chromatography ( meoh : h 2 o = 3 : 1 ), and 10 . 0 g of each of 100 fractions was collected by a fraction collector . these fractions were separated into six fractions ( gbd - 2 - 1 to gbd - 2 - 6 ). among said six fractions , the gbd - 2 - 5 fraction was fractionated by silica gel column chromatography ( chcl 3 : meoh = 100 : 1 ) to obtain 20 . 0 g of each of 250 fractions . these fractions were separated into five fractions ( gbd - 2 - 5 - 1 to gbd - 2 - 5 - 5 ). among said five fractions , the gbd - 2 - 5 - 2 fraction was purified by preparative tlc ( chcl 3 : meoh = 10 : 1 to chcl 3 : meoh = 3 : 1 ) to obtain gbd - 2 - 5 - 2a . on the gbd - 2 - 5 - 2a fraction obtained in example 1 , ei - ms ( electron impact ionization mass spectrometer ) were measured using jeol jms - sx102a ( jeol ltd , japan ). also , 1d nmr ( 1 dimensional nuclear magnetic resonance ) measurements , including 1 h - nmr , 13 c - nmr and dept ( distortionless enhancement by polarization transfer ) spectra , and 2d nmr spectra , including 1 h — 1 h cosy ( correlation spectroscopy ), noesy ( nuclear overhauser and exchange spectroscopy ), tocsy ( totally correlated spectroscopy ), hmqc ( heteronuclear multiple quantum coherence ) and hmbc ( heteronuclear multiple bond coherence ) spectra , were measured using varian unity - inova 500 mhz . as an internal standard , tms ( tetramethylsilane ) was used , and as a solvent , methanol - d 4 was used . the measurement results are shown in fig3 , 4 and 5 . ei - ms m / z : 356 ([ m ] + , molecular ion ), 312 ( base ion ). hrei - ms m / z : 356 . 1268 ([ m ] + , calcd . for c 20 h 20 o 6 , 356 . 1268 ). 1 h - nmr ( 500 mhz , methanol - d 4 ): δ 1 . 89 ( 2h , m , h - 9 ), 2 . 76 ( 2h , t , j = 7 . 5 , 15 . 5 hz , h - 8 ), 3 . 60 ( 2h , t , j = 7 . 0 , 13 . 5 hz , h - 10 ), 3 . 92 ( 3h , s , 3 ′- ome ), 3 . 99 ( 3h , s , 6 - ome ), 6 . 80 ( 1h , s , h - 7 ), 6 . 86 ( 1h , d , j = 8 . 5 hz , h - 5 ′), 7 . 33 ( 1h , dd , j = 2 . 0 , 8 . 5 hz , h - 6 ), 7 . 38 ( 1h , d , j = 2 . 0 hz , h - 2 ′), 7 . 53 ( 1h , s , h - 4 ), 10 . 19 ( 1h , s , 3 - cho ). 13 c - nmr ( 125 mhz , methanol - d 4 ): δ32 . 38 ( t , c - 8 ), 34 . 72 ( t , c - 9 ), 55 . 23 ( q , 3 ′- ome ), 55 . 44 ( q , 6 - ome ), 61 . 13 ( t , c - 10 ), 108 . 70 ( d , c - 7 ), 111 . 41 ( d , c - 2 ′), 113 . 04 ( d , c - 4 ), 115 . 32 ( s , c - 3a ), 116 . 88 ( s , c - 1 ′), 116 . 97 ( d , c - 5 ′), 123 . 89 ( d , c - 6 ′), 127 . 59 ( s , c - 3 ), 140 . 11 ( s , c - 5 ), 141 . 45 ( s , c - 7a ), 144 . 77 ( s , c - 6 ), 149 . 89 ( s , c - 3 ′), 155 . 64 ( s , c - 2 ), 167 . 74 ( s , c - 4 ′), 187 . 36 ( d , 3 - cho ). hmbc : h - 9 → c - 8 / c - 10 / c - 5 , h - 8 → c - 9 / c - 10 / c - 4 / c - 5 , h - 10 → c - 8 / c - 9 , 3 ′- ome → c - 3 , 6 - ome → c - 6 , h - 7 → c - 7a , h - 5 ′→ c - 1 ′/ c - 3 ′, h - 6 → c - 2 ′/ c - 2 / c - 4 ′, h - 2 ′→ c - 6 ′/ c - 3 ′/ c - 2 / c - 4 ′, h - 4 → 7a , 3 - cho → c - 3a / c - 3 . as can be seen from the measurement results , the gbd - 2 - 5 - 2a fraction was 5 -( 3 - hydroxyprophy )- 6 - methoxy - 2 -( 3 ′- methoxy - 4 ′- hydroxyphenyl )- 3 - benzo [ b ] furancarbaldehyde represented by formula ( 1 ): the compound of formula ( 1 ) had a molecular formula c 20 h 20 o 6 and a molecular weight of 356 . the antiplatelet activity of 5 -( 3 - hydroxyprophyl )- 6 - methoxy - 2 -( 3 ′- methoxy - 4 ′- hydroxyphenyl )- 3 - benzo [ b ] furancarbaldehyde , the novel compound of formula 1 isolated from the ginkgo biloba bark in example 1 , was measured . to measure the activity against collagen - stimulated platelet aggregation of the novel compound identified from the ginkgo biloba bark , concentrated human platelet - rich - plasma ( prp ) was first prepared . the prp used in the present invention was obtained by collecting blood from volunteers in hallym university medical center , centrifuging the blood at 1 , 000 rpm and room temperature for 10 minutes to collect pure supernatant prp and centrifuging the supernatant prp at 3 , 000 rpm and room temperature for 10 minutes . the obtained prp was separated into platelet - poor plasma ( ppp ) and platelets ( plts ). then , concentrated prp was prepared in the following manner . that is , platelets ( plts ) were suspended in a suitable amount of the supernatant ppp and measured for absorbance at 660 nm using a uv / visible spectrophotometer . based on the measured absorbance , the suspension was further diluted with an excess of ppp to prepare concentrated prp containing 5 × 10 8 platelets / ml . herein , an od value of 1 . 1 at 660 nm means 1 × 10 8 plts . a washing buffer used in the present invention was a ph 6 . 5 buffer containing 129 mm nacl , 10 . 9 mm sodium citrate dihydrate , 8 . 9 mm nahco 3 , 1 mg / ml glucose , 10 mm tris - hydroxymethylaminomethane , 2 . 8 mm kcl , 0 . 8 mm kh 2 po 4 and 2 mm edta . also , a suspension buffer used in this test example was a ph 6 . 9 buffer , which was the same as said washing buffer , except that it contained no edta . the platelet aggregation inhibitory effect of the novel compound was examined using the prepared concentrated prp in the following manner . first , the concentrated prp was used to make 500 μl of an in vitro reaction system . for use as a control group , the concentrated prp was stabilized at 37 ° c . for 3 minutes and treated with collagen ( chrono - log co .) as a stimulating agent at a concentration of 10 μg / ml , and the aggregation of platelets in the reaction system was induced for 5 minutes . meanwhile , the same reaction system as described above was treated with the novel compound , was allowed to react with the novel compound for 3 minutes , was stimulated with collagen for 6 minutes according to the same method as described above so as to induce platelet aggregation , and then was measured for aggregated platelets . the aggregation of platelets was measured with a change in light transmission using an aggregometer ( chrono - log co .) at 37 ° c . the measurement results are shown in table 1 below and fig6 , 7 and 8 . table 1 summarizes the antiplatelet aggregation activities of aspirin , the novel compound and ginkgolide a and b against platelet aggregation factors , including adp , collagen and arachidonic acid . as shown in table 1 , aspirin showed ic 50 ( half maximal inhibitory concentration ) values of 316 μm and 203 μm against aggregation factors adp and collagen , respectively , and the novel compound and ginkgolide a and b did not show an effect against the aggregation factor adp , but showed ic 50 values of 680 , 482 and 480 μm , respectively , against collagen - stimulated platelet aggregation . in the case of the group treated with the novel compound , when arachidonic acid was used as the aggregation factor , the aggregation of platelets occurred only upon stimulation with 1 , 000 μm ( i . e ., 1 mm ) or higher concentration of arachidonic acid . in the case of the groups treated with ginkgolide a and b , arachidonic acid - stimulated platelet aggregation did not occur . fig6 is a graphic diagram showing the inhibitory activity of aspirin on collagen - stimulated platelet aggregation . as shown in fig6 , aspirin inhibited platelet aggregation in a concentration - dependent manner . fig7 is a graphic diagram showing the inhibitory activity of the novel compound isolated from ginkgo biloba on collagen - stimulated platelet aggregation . as shown in fig7 , the novel compound inhibited collagen - stimulated platelet aggregation in a concentration - dependent manner . fig8 is a graphic diagram showing the inhibitory effect of each of gingkolide a and b on collagen - stimulated platelet aggregation . as shown in fig8 , each of gingkolide a and b inhibited collagen - stimulated platelet aggregation in a concentration - dependent manner . as described above , it can be seen from said example and test example that the inventive novel compound isolated from the ginkgo biloba bark has antiplatelet activity . thus , according to the present invention , the novel compound isolated from the ginkgo biloba bark can be provided . also , the novel compound according to the present invention is a natural substance , and thus has no side effects caused by synthetic compounds . also , the novel natural compound having antiplatelet aggregation activity can be extracted from the leaf or bark of ginkgo biloba and used as a natural antithrombotic agent having collagen - stimulated platelet aggregation effects . moreover , the novel compound isolated from the the ginkgo biloba bark can inhibit thrombus formation induced by collagen . furthermore , the novel compound can may inhibit serotonin secretion caused by collagen , which performs an important role in thrombus formation . also , it can may inhibit the activity of guanylate cyclase acting as a mediator in a mediator in a signaling process associated with thrombus formation and inhibit an increase in intracellular calcium ions as secondary signaling substances of thrombus formation . in addition , the inventive novel compound shows effects similar to those of gingkolide a and b , which have been used as antithrombotic compounds in the prior art . thus , a composition containing the novel compound has excellent antithrombotic effects and can be used for the treatment of diseases , including arteriosclerosis , cerebral hemorrhage , cerebral stroke and cerebral infarction , which involve thrombosis . although the preferred embodiment of the present invention has been described for illustrative purposes , those skilled in the art will appreciate that various modifications , additions and substitutions are possible , without departing from the scope and spirit of the invention as disclosed in the accompanying claims .
disclosed herein are a novel compound isolated from ginkgo biloba and a method for isolating the novel compound from ginkgo biloba . the method comprises : extracting ginkgo biloba with alcohol to obtain a crude extract ; subjecting the ginkgo biloba crude extract to solvent fractionation using an organic solvent ; fractionating the solvent fractions by sephadex column chromatography ; and fractionating the sephadex fractions by silica gel column chromatography .