Sudha Jain

Biosynthesis of isotetrandrine

Abstract The incorporation of (±)-coclaurine, (±)-N-methylcoclaurine, didehydro-N-methylcoclaurinium iodide, (+)-( S )-N-methylcoclaurine and (−)-( R )-N-methylcoclaurine into isotetrandrine in Cocculus laurifolius DC has been studied and specific utilization of (±)-, (+)-( S )- and (−)- R -N-methylcoclaurines and didehydro-N-methylcoclaurinium iodide demonstrated. The evidence supports intermolecular oxidative coupline of (+)-( S )- and (−)-( R )-N-methylcoclaurines to form isotetrandrine. Double labelling experiment with (±)-N- [ 14 C] methyl [1 - 3 H] coclaurine demonstrated that the hydrogen atom at the asymmetric centre in N-methylcoclaurine is retained in the bioconversion into isotetrandrine.

The biosynthesis of the alkaloids of stephania glabra (ROXB.) miers

Tracer experiments show that the tetrahydroprotoberberines stepholidine (14), corydalmine (d15), capaurine (19) and corynoxidine (20) are stereospecifically biosynthesized from (S)-reticuline (22) whereas the bisbenzylisoquinoline alkaloids cycleanine (52), N-desmethylcycleanine (51) and the proaporphine alkaloids. pronuciferine (27) and stepharine (26) are derived from (R)-N-methylcoclaurine in young Stephania glabra. The quaternary protoberberine alkaloids (40 to 44) of the plant are formed by dehydrogenation of the corresponding tetrahydroprotoberberines.

The biosynthesis of the alkaloids of croton sparsiflorus morong

Abstract Incorporation of tyrosine, dopa, dopamine, 4-hydroxyphenylpyruvic acid, (±)-, norcoclaurine-1-carboxylic acid, -norcoclaurine, -coclaurine, and -N-methylcoclaurine into N-methylcrotsparine, N-methylcrotsparinine and N-methylsparsiflorine in Croton sparsiflorus Morong has been studied. The evidence supports the direct oxidative coupling of (+)-, and (-)-N-methylcoclaurines to give N-methylcrotsparine and N-methylcrotsparinine respectively. Tracer experiment show that N-methylcrotsparine undergoes dienone-phenol rearrangement to give N-methylsparsiflorine. A double labelling experiment with (±)-N[14C]methyl[1-3H]coclaurine demonstrated that the H atom at the asymmetric centre in the 1-benzylisoquinoline precursor is retained in the bioconversion. The intermediacy of norcoclaurine-1-carboxylic acid and specific incorporation of dehydro-N-methylcoclaurinium salt into the bases have been demonstrated.

Alkaloids of cocculus laurifolius D.C.

Ten new abnormal Erythrina alkaloids, isococculidine, isococculine, coccuvine, coccuvinine, cocculitine, cocculitinine, coccudinone, cocculimine, coccudienone, coccoline and coccolinine have been isolated from the leaves of Cocculus laurifolius D.C. and their structures and stereochemistry is assigned by chemical transformations and spectral studies. The known proaporphine alkaloid stepharine and the morphinandienone alkaloid, sebiferine have also been isolated for the first time from the plant.

Biosynthesis of the bisbenzylisoquinoline alkaloid, tetrandrine

Abstract The incorporation of (±)-coclaurine, (±)-norcoclaurine, (±)- N -methylcoclaurine and didehydro- N -methyleoclaurinium iodide into tetrandrine in Cocculus laurifolius has been studied and specific utilization of (±)- N -ethylcoclaurine demonstrated. The evidence indicates that tetrandrine is formed in the plants by oxidative dimerization of N -methylcoclaurine. Double labelling experiment with (±)- N - [ 14 C]-methyl- [1- 3 H]-coclaurine demonstrated that the hydrogen atom at the asymmetric centre in the 1-benzylisoquinoline precursor is retained in the bioconversion into tetrandrine. Parallel feedings of (+)-( S )- and (−)-( R )- N -methylcoclaurines showed that the stereospecificity is maintained in the biosynthesis of tetrandrine from the 1-benzylisoquinoline precursor.

Biosynthesis of tetrahydropalmatine and palmatine

Abstract The incorporation of (±)-norlaudanosoline, norprotosinomenine, nororientaline, norlaudanidine, reticuline and laudanosine into tetrahydropalmatine and palmatine has been studied, and specific utilization of reticuline demonstrated. Feeding of (±)-[N-methyl-14C] reticuline showed that C atom 8 of tetrahydropalmatine and palmatine are formed by oxidative cyclisation of the N-Me group of reticuline. Parallel experiments with (R)-; and (S)-, reticulines demonstrated specific incorporation of (R)- isomer into these bases. Feeding experiments also revealed that the plants can convert tetrahydropalmatine into palmatine with high efficiency.

The biosynthesis of the alkaloids of cissampelos pareira linn

Tracer experiments show that the bisbenzylisoquinoline alkaloid, (S,R)-hayatidin (10) is stereospecifically biosynthesized in young Cissampelos pareira Linn plants by intermolecular oxidative coupling of (S)-(5)-and (R)-(3), N-methylcoclaurines whereas (R,R)-isochondrodendrine (14) and (R,R)-bebeerine (12) are formed in the plants by oxidative dimerization of (R)-N-methylcoclaurine (3).

Absolute configuration and biosynthesis of (+)-sinactine

Abstract The incorporation of norreticuline, reticuline and nororientaline into sinactine in Cocculus laurifolius DC has been studied and specific utilization of reticuline demonstrated. Feeding with N-[14CH3]reticuline showed that the C atom 8 in sinactine is derived from N-Me group of reticuline. Feeding of (±)-[1-3H, 3-14C]norreticuline and degradation of biosynthetic sinactine established that the regiospecificity is maintained in the bioconversion of 1-benzyltetrahydroisoquinoline precursor into the tetrahydroprotoberberine alkaloid. Further feeding of doubly labelled precursor demonstrated that the H atom at the asymmetric centre in reticuline is retained in the bioconversion into sinactine. Feedings of labelled scoulerine and tetrahydropalmatrubine established the intermediacy of scoulerine in the biosynthesis and suggested that the methylenedioxy group formation probably precedes O-methylation in the bioconversion of scoulerine into sinactine. Parallel feedings of (R)-, and (S)-reticulines and chemical conversion of (+)-sinactine into (+)-(R)-tetrahydropalmatine established that (+)-sinactine has R-configuration at the asymmetric centre C-13a.

Biosynthesis of magnoflorine and laurifoline

Abstract The incorporation of (±)-, nor-laudanosoline, nor-protosinomenine, nor-orientaline, norreticuline and reticuline and reticuline methiodide into magnoflorine and laurifoline has been studied and specific incorporation of nor-reticuline and reticuline demonstrated. Parallel feeding experiments with (+)- S and (−)-( R )-reticulines demonstrated specific incorporation of (+)-( S )-isomer into these bases.

The biosynthesis of the alkaloids of Corydalis meifolia Wall.

Abstract Tracer experiments show that corlumine, cavidine and yenhusomine are stereospecifically biosynthesized from (R)-(—)-reticuline.