We studied the effects of 37 flavonoids on prostaglandin endoperoxide synthase (EC 1.14.99.1) purified from sheep vesicular glands. Nonplanar flavans were more potent inhibitors than planar flavones and flavonols (IC50 values were, e.g., 40 µmol/l for catechin and epicatechin, 110 µmol/l for galangin, 490 µmol/l for quercetin and 450 µmol/l for kaempherol). Different inhibition mechanisms were observed, i.e. uncompetitive inhibition for nonplanar flavonoids and competitive or noncompetitive inhibition for planar flavonoids. Potent inhibitors in the group of flavones were substances with an o-dihydroxy structure in the B ring and in the group of flavonol substances with two hydroxyl groups in position 5 and 7 of the A ring. None of the flavanones studied caused significant inhibition, except for the fiavanone-3-ol, silibinin (silybin), which caused potent inhibition with an IC50 of 120 µmol/l. Several flavonoids, which were able to inhibit the prostaglandin endoperoxide synthase at higher concentrations, were also able to stimulate the enzyme at lower concentrations. These results indicate that the flavonoids should be divided into two groups according to their capacity to inhibit the prostaglandin endoperoxide synthase, represented by planar and nonplanar substances as in each group a close correlation between structure and inhibitory activity was observed.
J. C;iiiIaint)r 11. t:. \.. firu(+litiniisen: C'oiycctvinuiitl 1'i.oLopiii. 97Was t l k Phenolbasen bet,rifft, so wurde die natronalkr~lisc~c Liisuiig niit Yalzsiirirc: sawr geinarht und dann niit Na.triunibikarbonat, wieder alkalisch. Diesc Liisung wurde niit ..\ether ausgtwhiittclt. Nehen einern harzigen Anteil zeigte der Aethtwiickstand eirie Anzahl Krystallc, die mechanisch aiisgelcsen wurtltm rind sich als Prot.opin erwirstm. Die Trcnnung beim IGllcii rriit Satronlaiigc! war also nicht ganz vollkommcn gewesen. Kine Heinigung des Rurkstandcs tlurcth Vrrwandlung in das winsaurv Salz gclang nicht,. Es bildete Nich weder init Links-\Vein~iiurv noch init Kcc*hts-\Vt.insiiure in nriinenswertor RZcrige ein schwer liislichea Bitartrat. 13eini Ausschutteln der winsauren L6sung nach Zugabc von Xtttriunibikarbonat konntcn aus cleni .Arther neben harzigen Stoffcn Krystallr rrhalten ivrrdrm, (lit) folgendc Farbreaktionen c.rgahtw : F r ij 11 tl e : hriiunlich, schinutzig grau, ubcr Griin in Blau :K o n z e n t r i e r t c S c h H' c f c 1 s ii ti r (b: rotviolett. Die \Vciterfuhrurig t1c.r Arl)r.it wurcle (lurch den Krichg vcrhinclcrt.. l)a cs liingttrc Zeit daucrn wird, bis neurs Untcrsuchungsmaterial vorhandrn ist, solltcm (lit: bishrrigcw Ergehnissc? in allvr K iirze vrtriiffrnt,licht, wertlen. sclilielllich dunkelgriin, Mitteilung aus dem harmazeutisch-chemischen Institut der rp niversittit Marburg. 73. Beitrgge zur Kenntnis des Corycavins und Protopins. Von .J. G a (1 a. iii e r rind F. v. B r u c h h a 11 a e 11. (I'iiigt~~tiii~t~ii { l c , t i 2. 1'. 1922.)JHe Erforsrhung tler Alkaloide dcr Cor dalis, cava ist phyto-c4ieniiscli von hesonderein Intercsw. Diere hlanze gehiirt, c.benso \vie Papaver somnifrruni, zu den Pa1iavcmcc.m untl gcwdc tlict \'cr\vanrltscliaft niit dieser Pflanzt., . tlic tlurc.li cite JIannigfalt igltrit l i n t 1 tlic liesontlcrc: \Vichtigl;cit ihwr ~U a l o i d e hcrvorsticht., l i c 4 von drni Studiuni der Cor~rlalisallialoitlc wichtige Ergrbnisse tit,ziiglich tks Xuf baiies der Alkaloide in der Pflanze erwarttvi. Auc.1) dic grolk Zalil tler in tler C'orydalis\vurzel vorltomniendcn ; U l i d~i t l~, durcli clic: die ('orydalis eiii viilligcls Analogon dca Mohns w i d , durfte eine Fiirderung phytochcmischcr Erkenntnis rrhoffen lassen. Arcb. d. Pbum. WLX. Bdr. 2. Heft.
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