Alkaloids from leaves of Kopsia larutensis

Corynanthean, eburnan, secoleuconoxine, and pauciflorine alkaloids from Kopsia pauciflora

“…The ESIMS of 14 showed an [M+H] + peak at m/z 295, while the HRESIMS measurements established the molecular formula as C 19 H 22 N 2 O (DBE 10). The NMR spectroscopic data of 14 (Tables 2 and 3) were generally similar to those of larutenine (15) (Kam et al, 1992), with the presence of signals due to an unsubstituted indole moiety (d 7.05-7.42), an isolated aminomethine due to H-21 at d 3.23 (axial bridgehead hydrogen within a trans-quinolizidine skeleton), and the characteristic H-16 resonance at d 5.92 (d, J = 4 Hz). Several important differences were however noted which indicated changes involving ring F. In the 1 H NMR spectrum of 14 (compared with those of 15), a methyl doublet and an oxymethine were seen at d 1.33 (J = 6.3 Hz) and 3.95 (q, J = 6.3 Hz), respectively.…”

Biosynthetic Enantiodivergence in the Eburnane Alkaloids from Kopsia

“…In the earlier studies of Kopsia species from Peninsular Malaysia (Malaya), a number of known and new eburnane-type alkaloids were isolated. The commonly found eburnane alkaloids such as (+)-eburnamonine ( 1 ), (−)-eburnamine ( 2 ), (+)-isoeburnamine ( 3 ), and (+)-eburnamenine ( 4 ), isolated from K. larutensis , − K. griffithii , , and K. terengganensis ( K. profunda ), did not present a problem. All were pure enantiomers and had 20 R , 21 R absolute configurations (20β, 21β orientations) from the sign and magnitude of the specific rotations reported (Table ).…”

Chemical Constituents from Strychnos Cathayensis

“…The other known com pounds in cluded 18 al ka loids, cantleyine, 11 venoterpine, 12 nic o tinic acid, 13 4-methoxy-2quinolone, 14 (+)-eburnamonine, 15 har man, 16 strych nine, 17 brucine, 17 3-formylindole, 18 gramine, 19 tryptoline, 20 6methoxy-1,2,3,4-tetrahydro-1H--carboline, 21 harmalol, 22 allantoin, 23 guanosine, 24 thymidine, 25 adenosine 26 and thymine, 27 10 benzenoids, syringaldehyde, 28 vanillin, 29 3hydroxy-1-(4-hydroxyphenyl)-propan-1-one, 30 p-hydroxybenzoic acid, 31 gal lic acid, 31 vanillic acid, 32 isovanillin, 33 ben zoic acid, 34 methyl 3,4-dicaffeoyl quinate 35 and syringic acid, 36 4 ste roids, -sitosterol-3-O--D-glucoside, 37 -sitosterol, 37 pregnenolone 38 and stigmasterol, 39 2 triterpenoids, -amyrin 40 and squalene, 41 1 acetophenone, acetopiperone, 42 2 fatty ac ids, stearic acid 43 and palmitic acid, 44 1 lignan, (+)sesamin, 45 1 coumarin, osthole, 46 1 chromane, -tocopherol, 47 1 tetraterpenoid, -car o tene, 48 3 iridoids, siphonostegiol, 49 loganetin 50 and loganin, 51 1 secoiridoid, sweroside, 52 3 flavonoids, lu teo lin, 53 rutin 54 and quercetin, 54 1 polyphenol, corilagin, 55 1 or ganic acid, shikimic acid. 56 These com pounds were iden ti fied by com par i sons of their spec tral data (UV, IR, 1 H NMR, MS) with the data from the lit er a ture or with authen tic sam ples.…”