Forsythia spp

There are also many examples that highlight the stereochemical diversity of lignan biosynthesis, as observed in a cell-free extract of Arctium lappa petiole [35], which afforded secoisolariciresinol with the opposite antipode (+) to that formed by Forsythia spp. 

Umezawa, T., Okunishi, T. and Shimada, M. (1998) Stereochemical differences in lignan biosynthesis between Arctium lappa, Wikstroemia sikokiana, and Forsythia spp. ACS Symp. Ser., 697, 377-88. 

Carefully designed labeling experiments have conclusively established the biosynthetic origin of (-)-matairesinol in Forsythia spp. Cell-free enzyme preparations of F. suspensa stems catalyze the stereoselective coupling of two molecules of [8-14C]coniferyl alcohol to form (+)-pinoresinol in enantiomeric excess [24], This reaction likely involves the coupling of free radicals of coniferyl alcohol and is mediated by two enzymes an oxidase and a dirigent protein that controls the... 

Fig. (4). Proposed lignan biosynthetic pathway in Podophyllum (steps 1-3 have been characterized in Forsythia spp.). 1, Oxidase and dirigent protein create an 8-8 bond between two molecules of coniferyl alcohol 2, NADPH reductase catalyses two sequential reactions 3, NADP+ dehydrogenase. Dotted arrows indicate multiple uncharacterized steps.

Various reports on the antihypertensive activity of lignans were published before 1997 [14], ( )-Pinoresinol diglucoside from Eucommia ulmoides (Eucommiaceae), pinoresinol monoglucoside from Forsythia spp., sesamin from sesame oil, neojusticin B from Justicia procumbens, ephedradine B (a hybrid neolignan-alkaloid) from Ephedra spp.(Ephedraceae), danshensuan B from Salvia miltiorrhiza (Labiatae) and magnolol from different sources were all reported to be hypotensives in different animal models. 

Numerous other activities have been reported for PhGs, particularly from Plantago spp. and Forsythia spp. A comprehensive review of the pharmacological activities of this group is available (Cometa et al. 1993). 

Damtoft et al. carried out feeding experiments in Forsythia viridissima and F. europaea using deuterium-labeled deoxyloganic acid and found incorporation into forsythide (36). On the basis of the results, they concluded that deoxyloganic acid was oxidized at C-10 to adoxosidic acid followed by further oxidation at C-10 to forsythide in Forsythia spp. [71]. 

Damtoft S, Franzyk H, Jensen SR (1994) Biosynthesis of iridoids in Forsythia spp. Phytochemistry 37 173-178... 

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