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J ournal of South China University of Technology A rticl e ID : 10002565X (2003) 0920070206 Si m ult a n e o us D e t e cti o n of L a ct o n e For m a n d Aci d For m M o n a c oli n K b y S e nsiti ve TL C M e t h o d (1. College of Food & Biological Engineering , South China Univ. of Tech. , Guangzhou 510640 , China ; 2. Dept . of Food Sci . & Tech. , College of Agricutural Life Sci . , Chungnan National Univ. , Taejon 305 - 764 , Korea ; 3. Daedok Biotechnique Inc . , Taejon 305 - 764 , Korea) A bs t r act : A novel and sensitive thin2layer chromatography ( TLC) method for specific and simultaneous detection of both lactone form Monacolin K and acid form Monacolin K is developed in this study. The TL C works in the fol2 lowing conditions : The TL C plate was Silica Gel 60 , RP - 18 F254 , 0. 5 mm , chemically modified layer , Merck , Germany ; The solvent system was chloroform methanol ammonium hydroxide = 25 3 1 ( volume ratio) ; Moni2 toring the TL C under 365 nm after heating it with a slight coating of the charring reagent 30 % ( volume fraction) H2SO4 ethanol on the TL C plate , allowed the specific detection of Monacolin K and the low detection limit was first time brought down to 30 ng. The present TL C method is suitable for the routine qualitative and semi2quantitative analysis of the bulk materials containing Monacolin K.
Ke y w or ds : thin2layer chromatograhpy ; lactone form Monacolin K; acid form Monacolin K Monacolin K (also called lovastatin) possesses var2 Monacolin K : lactone f orm and acid f orm ( refer to Fig.
ious medical f unctions such as lowering high level blood cholesterol [ 1 3 ] , anticancer[4 ,5 ] and promoting bone f or2 In our previous study we have developed a si2 mation[6 , 7 ] . Bef ore 1994 only pigment red rice was pro2 multaneous detection method f or both L FM K and AFM K duced but after that the f unctional red rice which contains by RP2HPL C in our lab[10] , but HPL C not only takes monacolin K appeared in the market[8 ] . Theref ore in the much time , but also is rather expensive . The method of market there are both pigmental and f unctional red rice double wave2length UV spectrophotometry was also re2 or their products . The f unctional red rice or its product ported , but it requires sample pre2treatment through a was f urther divided into different grades according to its neutral aluminum oxide column and is theref ore quite complicated[11 ]. So far the best reported TL C system 1. 0 % ( mass fraction , the following is the [ 12 ] uses silica gel plate , the developing reagent of hex2 same) [9 ] . So it is very important to develop a rapid and ane acetone = 1 1 ( volu2me ratio , the following is the easy method to analyze total Monacolin K in red rice or same) and the iodine as the colorant f or the separated spots . The observation condition is under daylight . The Study[3 ] has proved that there are two f orms of reported TL C method can detect only L FM K and its lower detection limit was 10 000 ng , while the usual loading amount of standard Monacolin K was 40 000 ng.
Bi ogr ap h y : Wang Qi2jun (born in 1972) , male , Ph. D , lec2 As to AFM K , since it is not commercially available , turer , mainly researches on bioengineering and food ana2lysis .
moreover , its lower detection limit is as low as that of L FM K with common TL C method ( indicated in this Wang Qi2jun et al : Simultaneous Detection of Lactone Form and Acid Form Monacolin K by Sensitive TL C Method study) , theref ore it can not be detected by common TL C methods . In the present study we have developed a sen2 sitive , rapid and economical TL C method which allowed AFM K so far is not commercially available and it is the qualitative , quantitative ( approximately) and simul2 prepared from L FM K in our laboratory. The stan2dard of taneous detection of L FM K and AFM K when observed L FM K was purchased from Sigma , and 1 mg/ mL of under 365 nm UV light after charred with 30 % H L FM K in 80 % acetonitrile water solution was used to ethanol . And this method can be used to monitor Mona2 obtain AFM K in solution by alkaline treatment with 0. 1 colin K content during fermentation , and to estimate the kg/ mol NaOH. The p H value was estimated with p H test paper . AFM K was confirmed by L C/ MS .
quality of red rice or Monacolin K containing medicine .
The procedures of Monacolin K extraction from red rice or its solid products mainly f ollowed the method de2 scribed by Moon[10 ] . 0. 200 g red rice powder or its product was extracted with 1 mL 60 % acetonitrile water solution in 1. 5 mL Enpendorf tube by sonicating f or 20 . The extract was then centrif uged at 12 000 r/ min for 5 minutes . The supernatant was stored at if not directly used f or analysis .
S t a n d a r ds a n d R e d Ric e S a mp l es tract were loaded on a TL C plate . After air dried , the L FM K was purchased from Sigma Chemical Co. , TL C plate was developed in a presaturated solvent cham2 New York , USA . Functional red rice of FHQF and the medicinal capsule of Xuezhikang were kindly donated by ber. Bef ore the solvent front reaching the end of the Professor Zhou Li2ping of Zhejiang Univ. of Tech. , TL C plate , the TL C plate was removed from solvent Hangzhou , China . The pigmental red rice of HQF was chamber and sprayed with an even coating of 30 % H2SO4 ethanol charring reagent with a TL C sprayer (Merck , Germany) . Then the TL C plate was observed K5 Silica Gel 150 , 0. 25 mm and K6 Silica Gel and photographed under 365 nm after being heated on a 60 , 0. 25 mm were from Whatman , USA . Silica Gel 60 , F254 , 0. 5 mm , Silica Gel 60 , F254 , 0. 5 mm , a2 luminum sheet and Silica Gel 60 , RP - 18 , F254 , 0. 5 mm , chemically modified layer were from Merck , Pr ep a r a t i o n of A FM K f r o m L FM K AFM K was prepared in liquid solution by alkaline hydrolysis of lactone f orm Moancolin K. The hydrolysis Acetonitrile , methanol , chlorof orm , hexane and results were shown in Table 1. Treatment No. 3 was acetone were purchased from Burdick & J ohnson USA , used to prepare the standard solution of AFM K. The converted AFM K was confirmed by L C/ MS ( refer to ammonium hydroxide was from Sigma Chemical Co.
USA . All other chemicals were of analytical reagent grade , and obtained from Yakuri Pure Chemical Co.
J ournal of South China University of Technology (Natural Science Edition) Alkaline treatments of lactone form Monacolin K N ovel TL C D e t e ct i o n M e t h o d f or Fig. 3 shows the result obtained with the TL C plate 9 1 , 2. 0 L (i . e . around 1 g total Monacolin K) of 1) 0. 5 mg/ mL L FM K in 60 % acteonitrile water ; Novel TL C detection method for Monacolin K 5 : corresponding to the alkaline treatment from No. 2 to No. 6 in Table 1 ; Sample C : the standard lactone form Mona2 colin K of 1 000 ng (left) and 500 ng (right) .
(2) A : observed directly under 365 nm before spraying charring reagent , indicating Monacolin K itself had no fluorescence ; B : observed under day light as normal TL C method required after charring treatment , the signal were very faint ; C : observed under 365 nm after charring treatment , both L FM K and AFM K now showed bright yellow fluores2 (3) The Rf of LFM K was 0. 64 , the Rf of AFM K was 0. 025 A ( M + Na + = 404 + 23 ) : from the standard L FM K solution ; B ( M + Na + = 422 + 23 ) : from the solution of treatment No. 4 The TL C plate was observed step by step . First , in the acid form Monacolin K preparation test the plate was observed directly under daylight , under In the experiment it was f ound that if the amount of 254 nm UV light and under 365 nm UV light respective2 NaOH in acetonitrile water solution was more than a cer2 ly , and no spots could be recognized , indicating that tain amount compared to the amount of L FM K , the Monacolin K had no fluorescence reaction. Second , the L FM K could be converted completely into AFM K ( refer TL C plate was observed under daylight , after being to treatment No. 3 , 4 and 5) , but too much alkaline in sprayed with the charring reagent of 30 % H2SO4 ethanol the mixture could be harmf ul to both HPL C column and and being heated properly the plate on a hot plate ( if TL C plate . However if the amount of NaOH was not e2 over heated , the whole TL C plate will be spoiled) , and nough , L FM K was only partially converted into AFM K only faint gray spots (in fact hardly recognizable) shown (refer to treatment No. 1 , 2) , and the conversion ratio on the plate . Following the se2cond step , the TL C plate increased with the storing temperature and time ( data not was observed under 254 nm and the signals could not be enhanced by any degree , compared with observing at Additionally , we f ound that even under a very daylight. However when the TL C was observed under strong basic condition like treatment No. 6 , L FM K still 365 nm , and very bright yellow spots were found , indi2 could not be converted into Monacolin J . The conver2 sion of acid f orm Monacolin J f orm lactone f orm Mona2 cating that both L FM K and AFM K after being charred by colin K need to be f urther studied.
H2SO4 could produce yellow fluorescence under 365 nm.
Wang Qi2jun et al : Simultaneous Detection of Lactone Form and Acid Form Monacolin K by Sensitive TL C Method The result were photographed under 365 nm .
The low detection limit f or AFM K was also estimated , But the problem was that the spots of AFM K even and the result was shown in Fig. 5. The low detection did not move f orward in this TL C system . So the f urther limit was also around 30 ng. It was quite close to the screening work f or the proper mobile phases or other low detection limit of HPL C/ UV detection method , 20 ng. We supposed that such lower detec2 tion limit of this TL C system perhaps were also suitable f or the other Moncolin K analogs like Monacolin J , L , Five kinds of solvent systems , i . e . chlorof orm X , M and so on , since they share the basic common methanol = 9 1 ; hexane chlorof orm methanol = 9 3 1 ; hexane acetone = 1 1 ; chloroform methanol am2 monium hydroxide = 25 3 1 ; he2xane chloroform iso2 propanol = 6 3 1 and six kinds of TL C plates listed in the section of material and methods were tried f or screening the optimal stationary phase and mobile phase f or detecting Monacolin K. The most important part of the results were shown in Fig. 4. The optimal TL C plate as Silica Gel 60 , RP - 18 F254 , 0. 5 mm , chemically modified layer , Merck , Germany , and the optimal mo2 Sensitivity estimation of the screened TL C AFM K contents of spots 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 were 300 , 150 , L FM K and AFM K were 0. 62 and 0. 54 , respectively.
100 , 50 , 30 , 20 , 15 , 10 ng , respectively.
The low detection limit f or L FM K was 30 ng ( refer to In this experiment we f ound that after developing Fig. 4) . It should be pointed out that the mobile phase TL C plates of the kind F254 even in different mobile temperature could slightly affect the Rfs of both L FM K phases , sprayed with 30 % H2SO4 ethanol then heated on and AFM K , but it would not interfere the re2cognition under 365 nm , the bright yellow spots of both L FM K V ali di t y of t h e Sc r e e n e d TL C Considering a lot of other compounds in red rice , in order to confirm whether this yellow fluorescence was specific f or Monacolin K or not , two f unctional red rice samples of FHQF and Xuezhikang and one pigmental red rice of HQF as well as standard Monacolin K were ap2 plied to the screened TL C system . After developed , the TL C was also observed step by step . The results were (1) Samples on all of 3 plates were the same : 1 # 500 ng LFM K plus 500 ng AFM K , 2 # 20 ng L FM K , 3 # 30 ng L FM K , 4 # 50 ng It was f ound that this novel TL C method could L FM K. In each plate , the upper arrow pointing to L FM K , and the low2 greatly improve the resolution and sensitivity f or Mona2 colin K detection. L ots of other compounds in red rice (2) Plate A : Silica Gel 60 , F254 , 0. 5 mm , Merck , Germany , samples especially in pigmental red rice had fluorescence Rf = 0. 18 and 0. 00 ; Plate B : Silica Gel 60 , F254 , 0. 25 mm , alu2 minum sheet , Merck , Germany , Rf = 0. 18 and 0. 02 ; Plate C : Silica Gel 60 , RP - 18 F254 , 0. 5 mm , chemically modified layer , Merck , J ournal of South China University of Technology (Natural Science Edition) Validity of this novel TL C method estimated with red rice samples (1) A , B , C was from same one developed TLC plate but observed under different conditions . Samples of 1 ,2 ,3 ,4 ,5 : were 300 ng LFM K, 500 ng AFM K plus 500 ng L FM K; red rice powder FHQF (4 L of 5 times dilute) ; Xuezhi Kang (4 L of 5 times dilute) ; red rice powder HQF ( 4 L spotting from 5 X dilute) , respectively. In pattern A and B , arrow a pointed to L FM K; and arrow b pointed to AFM K. In photo C , all the arrows pointed to (2) A : observed at 365 nm after spraying 30 % H2SO4 ethanol and heating ; B : observed under day light , after spraying 30 % H2SO4 ethanol and heat2 ing ; C : directly observed at 365 nm before spraying 30 % H2SO4 ethanol , indicating many other compounds in red rice has fluorescence .
the charring reagent and heating , when observed under and the target components spots turned strong.
daylight as done in most reported TL C methods , there In conclusion , the developed TL C system greatly were many gray spots in both f unctional and pigmental improved the resolution of Monacolin K in red rice and rice . Theref ore even with the standard Monacolin K as f or the first time allowed the simultaneous detection of control , it was difficult to judge that in pigmental rice both L FM K and AFM K. The low detection limit was there was no Monacolin K. Furthermore , the standards brought down to 30 ng , which was quite near to that of spots of 500 ng Monacolin K were very weak too ( refer to Fig. 6 B ) . However , when observed under 365 nm plicity and rapidity of TL C , this method would be very after being heated , the bright yellow Monacolin K spots usef ul monitoring Monacolin K production during the became very clear and the standard of 300 ng Monacolin fermentation process or estimation of the Monacolin K K now could be seen clearly , and what is more impor2 tant , other interfering spots were not the problem any When this method is used , attention has to be paid Endo A . Monacolin K , a new hypocholesterolemic agent to the f ollowing two critical points . One is even spray of produced by a Monascus species [ J ] . J Antibiotics , 1979 , proper amount of 30 % H2SO4 ethanol .
Lin C F ,Demain A L . Effect of nutrition of Monascus sp . on H2SO4 will spoil the whole TL C plate , and too little will formation of red pigments [J ] . Appl Miccrobiol Biotechnol , also decrease the detection sensitivity. The other is even heating on a hot plate , keeping a close eye to the spots Moghadasian M H. Minireview of clinical pharmacology of color changing with the help of hand UV light while HMG2CoA reductase inhibitors [J ] . Life Science ,1999 , 65 : Addeo R ,Altucci L , Battista T , et al . Stimulation of human fermented red rice) colorf ul and obvious spots of other breast cancer mcf27 cells with estrogen prevents cell cycle components turned more and more faint while the spots arrest by HMG2CoA reductase inhibitors [ J ] . Biochemical of both L FM K and AFM K became more and more clear and Biophysical Research Communications , 1996 , 220 : 864 with the color changing from none to white to blue and then to yellow , under 365 nm . This color changing just Naderi S . L ovastatin inhibits G1/ S transition of normal hu2 met our needs : interfering component spots faded away man B2lymphocytes independent of apoptosis [ J ] . Experi2 Wang Qi2jun et al : Simultaneous Detection of Lactone Form and Acid Form Monacolin K by Sensitive TL C Method mental Cell Research , 1999 ,252 :144 - 153.
Moon Y J , Wang Q J . Detection of L FM K and AFM K in Conner W T. L ovastatin was safe and efficacious in adoles2 red rice by reverse phase2HPLC [J ] . Kr J Food & Nutri2 cent males with heterozygous familial hypercholeste2rolemia [J ] . Evidence2based Cardiovascular Medicine , 1999 (3) : 67 Wen J , Gu X L , Chang P , et al . Detection of L ovastatin Content of Red Rice by Double Wave Length UV Specto2 Wang J ,Li Z L , Chi J , et al . Multicenter clinical trial of the htometry [ M ] . Hangzhou : Zhejiang Univ. of Tech. Press , serum lipid2lowering effects of a Monascus Purpureus ( Red Yeast) rice preparation from traditional Chinese medicine Wei P L , Shi T L . Screening and Mutangenesis of [J ] . Current Therapeutic Research ,1997 ,27 : 322 - 327.
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Komagata D ,Shinada H , Murakawa S , et al . Biosynthesis of monacolins : conversion of Monacolin L to Monacolin J by Zhang M L , Duan Zh W , Xie Sh M . Study on the active a monooxygenase of Monascus rubber [J ] . J Antibiotics , compounds of XU EZHI KANG [J ] . J Chinese New Medicine ,1998

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