Methylenedioxy bridge, formation

Jiao, Y., Davin, L.B. and Lewis, N.G. (1998) Furanofuran lignan metabolism as a function of seed maturation in Sesamum indicum methylenedioxy bridge formation. Phytochemistry, 49, 387-94. 

In isoquinoline alkaloid biosyntheses, several unique P450 reactions have been reported, such as methylenedioxy bridge formation, intramolecular C-C phenol-coupling and intermolecular C-0 phenol-coupUng reactions. Salutaridine... 

RUEFFER, M., ZENK, M.H., Canadine synthase from Thalictrum tuberosum cell cultures catalyzes the formation of the methylenedioxy bridge in berberine synthesis. Phytochemistry, 1994, 36, 1219-1223. 

The formation of the methylenedioxy bridge in Berberis has been found to be caused by the demethylating activity of a peroxidase (POD) found within the vesicle. It was also found that the cytochrome P450-requiring enzyme (canadine synthase) from microsomes of Berberis, Thalictrum and Coptis species formed the methylene bridge in (S)-tetrahydrocolumbamine (Ikezawa et al, 2003), but not in the quaternary alkaloid columbamine (Galneder et al, 1988 Zenk, 1995). Because of the substrate specificity of canadine s)mthase, the berberine pathway is considered to be that presented in Fig. 2.5 (Rueffer and Zenk, 1994). Columbamine, once proposed as an alternative route to berberine, is however converted to palmatine by a specific methyltransferase first isolated from Berberis wilsoniae cell cultures (Rueffer and Zenk, 1985 Ikezawa et al, 2003). 

Ono, E., Nakai, M., Fukui, Y, Tomimori, N., Fukuchi-Mizutani, M., Saito, M., Satake, H., Tanaka, T., Katsuta, M., Umezawa, T. and Tanaka, Y. (2006) Formation of two methylenedioxy bridges by a Sesamum CYP81Q protein yielding a furofuran lignan, (+)—sesamin. Proc. Natl. Acad. Sci. USA., 103,10116-21. 

Diaz Chavez, M. L., et al.. Characterization of two methylenedioxy bridge-forming cytochrome P450-dependent enzymes of alkaloid formation in the Mexican prickly poppy Argemone mexicana. ArcA Biochem. Biophys., 2011. 507(1) p. 186-93. 

A9 Formation of methylenedioxy bridge in reticuline Pavine alkaloids Califomidine [81]... 

Taken together these experiments establish a) the formation of the berberine bridge by oxidative cyclization of the iV-methyl group, (6) the derivation of the methylenedioxy group by oxidative cyclization of the 0-methoxyphenol grouping, and (c) the validity of laudanosoline and reticuline as intermediates in the biosynthetic pathway. 

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