Biotransformation of Phenolic 1-Benzyl-N-methyltetrahydroisoquinolines in Plant Cell Cultures Followed by LC/NMR, LC/MS, and LC/CD

Abstract

(+/-)-1-Benzyl- N-methyltetrahydroisoquinolines 7-10 and 11-14 with one and two hydroxy groups on the aromatic rings, respectively, were fed individually to cultured cells of Corydalis and Macleaya species, respectively. The structures of the metabolites were determined by using combinatorial techniques, including LC/NMR, LC/MS-MS, and LC/CD. The enantiomeric excesses of the metabolites were derived from LC/CD and LC/MS-MS analyses. In cell cultures of Corydalis and Macleaya species, laudanine (7), with a hydroxy group at C-3', can form the berberine bridge at C-2' and C-6' to produce S- and R-enantiomers of 2,3,9,10- and 2,3,10,11-oxygenated protoberberines (20 and 21), respectively, whereas reticuline (11) and protosinomenine (12), incoporating a hydroxy group at C-3', form the berberine bridge at C-2' to furnish the S-enantiomer of 2,3,9,10-oxygenated protoberberines (23 and 21), respectively.

Bioactive benzylisoquinoline alkaloids from Artabotrys hexapetalus

“…In addition, the 1 H NMR spectrum of 1 also showed signals for three methoxy groups resonating at d H 3.15 (3H, s), 3.81 (3H, s), and 3.83 (3H, s), a N-methyl group at d H 3.21 (3H, s), four aliphatic protons as multiplet resonating at d H 2.92-3.68, as well as three mutual coupling upfield protons as an ABX system resonating at d H 4.46 (1H, dd, J = 9.8, 2.6 Hz), 4.03 (1H, dd, J = 12.4, 2.6 Hz), and 2.85 (1H, dd, J = 12.4, 9.8 Hz). All these indicated that alkaloid 1 possesses a benzylisoquinoline skeleton (Zhou et al, 1991;Cui et al, 2007). The 13 C NMR and DEPT data of 1 showed similarity with those of codamine (Brochmann-Hanssen et al, 1965), except for the characteristic downfield shifts of the carbon resonances at d C 79.6, 62.9, and 54.8 for C-1, C-3, and N-CH 3 , respectively, with respect to those of codamine.…”

“…Given that (+)-1S, 2S-laudanidine-N a -oxide and (+)-1S, 2R-laudanidine-N b -oxide hold the similar rotation values (½a 20 D þ 55 for 1S, 2S-laudanidine-N a -oxide and ½a 20 D þ 86 for 1S, 2R-laudanidine-N b -oxide) (Zhang et al, 2012), we could draw a conclusion that the rotation values of this type of benzylisoquinoline alkaloids mainly depend on the chiral center at C-1. From structural and biogenetic point of view, (+)-reticuline (3), also isolated from this plant by us, whose structure and absolute configuration had been determined by a combination of spectroscopic methods (Arbain et al, 1990;Cui et al, 2007;Blanchfield et al, 2003), hold the same chiral center at C-1 with that of alkaloids 1 and 2, and could be considered as model compound for assignment of the absolute configuration by comparison of rotation value, Hence, the absolute configurations at C-1 of alkaloids 1 and 2 were Sconfiguration, identical to that of (+)-reticuline, as determined by their similar specific rotation with 3 (½a 20 D þ 63:9). Another chiral center at N-2 in alkaloids 1 and 2 was determined by the difference in chemical shift for H-8 in 1 and 2, caused by the orientation of the Noxide.…”

Enantiomeric separation of racemic 1-benzyl-N-methyltetrahydroisoquinolines on chiral columns and chiral purity determinations of the O-methylated metabolites in plant cell cultures by HPLC-CD on-line coupling in combination with HPLC-MS

“…Compounds 2D-9D were administered to cell cultures of Corydalis platycarpa and Macleaya cordata (Cui et al, 2007) and the ether-soluble alkaloid fractions (Fig. 2, Fr.…”

“…It has been demonstrated that (±)-reticuline (6) and (±)-pseudosinomenine (7) were bioconverted to (S)-scoulerine and (S)- tetrahydropalmatrubine (Cui et al, 2007). (±)-Reticuline (6) and (±)-pseudosinomenine (7) may be biotransformed via (S)-laudanine (2) to (S)-tetrahydroprotoberberines.…”

“…These peaks corresponded to the (S) and (R) configurations at C-1, respectively. The LC-CD spectra of (±)-[N-CD 3 ]-tetrahydropapaverine (1D), -laudanine (2D), -codamine (3D), -pseudolaudanine (4D), pseudocodamine (5D), -reticuline (6D), -pseudosinomenine (7D), 6-O-demethylcodamine (8D), and -isoorientaline (9D) (Cui et al, 2007) were measured using three chiral columns (Chiralcel OJ-H, Chiralcel OD-H, and Chiralpak IB) and two solvent systems (N-hexane/isopropanol/ diethylamine and N-hexane/ethanol/diethylamine) under isocratic conditions (Table 1). Enantiomeric separations were achieved for all compounds using both Chiralcel OD-H and OJ-H columns with N-hexane/ethanol/diethylamine as eluent.…”