The antioxidative properties of the aporphines boldine, glaucine and apomorphine, and of the benzyltetrahydroisoquinolines (+/-)-coclaurine and (+/-)-norarmepavine were compared in the brain homogenate autoxidation model. The IC50 values found lay in the 16-20 microM range for the aporphines and were 131.7 microM, and 79.3 microM for coclaurine and norarmepavine, respectively. These results ind...

Fractionation of the chloroform extract from the aerial part of Argemone mexicana led to the isolation of two benzophenanthridine-type alkaloids, N-demethyloxysanguinarine and pancorine; three benzylisoquinoline-type alkaloids, (+)-1,2,3,4-tetrahydro-1-(2-hydroxymethyl-3,4-dimethoxyphenylmethyl)-6,7-methylenedioxyisoquinoline, (+)-higenamine and (+)-reticuline. Among them, N-demethyloxysanguina...

Benzylisoquinoline alkaloids (BIAs) are among the most important plant secondary metabolites, in that they include a number of biologically active substances widely employed as pharmaceuticals. Isolation of BIAs from their natural sources is an expensive and time-consuming procedure as they accumulate in very low levels in plant. Moreover, total synthesis is challenging due to the presence of s...

Plant alkaloids, one of the largest groups of natural products, provide many pharmacologically active compounds. Several genes in the biosynthetic pathways for scopolamine, nicotine, and berberine have been cloned, making the metabolic engineering of these alkaloids possible. Expression of two branching-point enzymes was engineered: putrescine N-methyltransferase (PMT) in transgenic plants of A...

Molecular clones encoding nine consecutive biosynthetic enzymes that catalyze the conversion of l-dopa to the protoberberine alkaloid (S)-canadine were isolated from meadow rue (Thalictrum flavum ssp glaucum). The predicted proteins showed extensive sequence identity with corresponding enzymes involved in the biosynthesis of related benzylisoquinoline alkaloids in other species, such as opium p...