Protoberberine alkaloid

Protoberberine Alkaloids.—In the course of the bioconversion of the proto-berberine scoulerine (65) into chelidonine (62) and phthalide-isoquinolines, e.g. narcotine (63), C-13 becomes oxidized.61 Ophiocarpine (68), with a hydroxy-group at C-13, represents an intermediate stage in the modification of the protoberberine skeleton, and results62 of tracer experiments have shown that scoulerine (65) is also to be included in the biosynthesis of this alkaloid. Tetrahydro-protoberberine (67) is also a precursor, its incorporation indicating that C-13 hydroxylation is a terminal step. As for other protoberberine derivatives,63 nandinine (64) was not assimilated,62 and it follows then that (65) is probably converted into (67) by way of isocorypalmine (66). 

Using chirally tritiated samples of the protoberberine (67) it has been established that hydroxylation of (67) to give (68) occurs with loss of the 13-pro-R hydrogen atom, i.e. normal retention of configuration, and does not involve an enamine intermediate since tritium is not lost from C-14 during the course of this biotransformation.62 It is to be noted that similar results, associated with C-13, have been observed61 for narcotine (63) and chelidonine (62) biosynthesis, except that here the 13-pro-S proton is removed. 

The probability63 that (69) lies along the pathway to protoberberine and derived alkaloids, between scoulerine (65) and stylopine (70), has been supported by the observation that tritiated (69) is a precursor for protopine (73), and also for corynoline (78).64 Evidence previously obtained for the intermediacy of the metho-salt of stylopine [as (71)] in the biosynthesis of chelidonine (62)63 and protopine (73)63,65 has been affirmed, and it is apparently the a-form (71) and not the /3-form that is involved. [The authors are mistaken in assuming that ( —)-stylopine has the R-configuration at C-14 cf. ref. 63]. 

A striking novel result is that [AT-meffty/-13C]protopine [as (73)] affords appropriately labelled chelidonine (62) and sanguinarine (72).64 Previously63 the formation of chelidonine (62) had been rationalized as involving a pathway through (71) 

Kamigauchi, and M. Sugiura, Chem. andPharm. Bull. (Japan), 1976,24, 2859. 

Alkaloid isolation and structural elucidation are summarized in Table 9. 23—343 structures of corynoxidine and epicorynoxidine, two new alkaloids from Corydalis 

Coptis japonica C. japonica (callus cultures) Corydalis cava 

Slavik and L. Slavikova, Coll. Czech. Chem. Comm., 1975,40, 3206. 

Dehydrocapaurimine chloride Dehydrocapaurine chloride Dehydrocorydalmine chloride Palmatine chloride Capaurimine Capaurine 

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Interaction of Protoberberine Alkaloids with Nucleic Acid Structures. . . 176... 

Protoberberine Alkaloid-Triplex Nucleic Acid Interaction. 194... 

Protoberberine Alkaloid-Nucleic Acid Quadruplex Interaction. 196... 

Abstract Protoberberine alkaloids and related compounds represent an important class of molecules and have attracted recent attention for their various pharmacological activities. This chapter deals with the physicochemical properties of several isoquinoline alkaloids (berberine, palmatine and coralyne) and many of their derivatives under various environmental conditions. The interaction of these compounds with polymorphic DNA structures (B-form, Z-form, H -form, protonated form, triple helical form and quadruplex form) and polymorphic RNA structures (A-form, protonated form, triple helical form and quadruplex form) reported by several research groups, employing various analytical techniques such as spectrophotometry, spectrofluorimetry, circular dichro-ism, NMR spectroscopy, viscometry as well as molecular modelling and thermodynamic analysis to elucidate their mode and mechanism of action for structure-activity relationships, are also presented. 

Protoberberine Alkaloids Physicochemical and Nucleic Acid Binding Properties 157... 

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