Rosemary F. Webby

7-O-methyl-(2R:3R)-dihydroquercetin 5-O-β-D-glucoside and other flavonoids from Podocarpus nivalis

Abstract In the course of a chemotaxonomic survey of New Zealand Podocarpus species, a number of new flavonoid glycosides have been isolated from P. nivalis . These are: luteolin 3′- O -β- D -xyloside, luteolin 7- O -β- D -glucoside-3′- O -β- D -xyloside, dihydroquercetin 7- O -β- D -glucoside, 7- O -methyl-(2 R :3 R )-dihydrokaempferol 5- O -β- D -glucopyranoside, 7- O -methyl-(2 R :3 R )-dihydroquercetin 5- O -β- D -glucopyranoside, 7- O -methylkaempferol 5- O -β- D -glucopyranoside and 7- O -methylquercetin 5- O -β- D -glucopyranoside. Diagnostically useful physical techniques for distinguishing substitution patterns in dihydroflavonols are discussed and summarized. Glucosylation of the 5-hydroxyl group in (+)-dihydroflavonols is shown to reverse the sign of rotation at 589 nm.

Flavonoid profiles of new zealand Libocedrus and related genera

Abstract Flavonoids common to both Libocedrus bidwillii and L. plumosa , which were sampled throughout New Zealand, are: kaempferol and quercetin 3-rhamnoside, kaempferol and quercetin 3-rhamnoside-7-glucoside, quercetin 3-glucoside, apigenin and luteolin 7-glucoside, luteolin 7-di- (and tri)-glucosides, amentoflavone, 7- O -methylamentoflavone, 2,3-dihydroamentoflavone, and the new flavonoids, 8-hydroxyapigenin and 8-hydroxyluteolin 7- O -xylosides and 7- O -methyl-2,3-dihydroamentoflavone. Libocedrus plumosa is distinguished by the additional accumulation of myricetin 3-rhamnoside, and L. bidwillii by the presence of quercetin 3- O -α-[2- p -hydroxybenzoyl-4- O - p -coumaroylrhamnopyranoside] which was found amongst the biflavones. A chromatographic survey of some related non-New Zealand species and genera is also reported.

Flavonol 3-O-triglycosides from Actinidia species

Abstract In the course of a chemotaxonomic study of the genus Actinidia, several new flavonol triglycosides have been characterised by 1H and 13C NMR spectroscopy. These are kaempferol and quercetin, 3-O-[α-rhamnopyranosyl-1-4)-rhamnopyranosyl-(1-6)-β-galactopyranoside, kaempferol 3-O-[α-rhamnopyranosyl-(1-4)-rhamnopyranosyl-(1-6)-β-glucopyranoside], and kaempferol 3-O-[α-rhamnopyranosyl-(1-4)-3‴-O-acetyl-α-rhamnopyranosyl-(1-6)-β-galactopyranoside]. Quercetin and isorhamnetin analogues of the dirhamnosyl glucoside were also detected.

The Unique Occurrence of the Flavone Aglycone Tricetin in Myrtaceae Pollen

In pollen, flavonoids are usually found as glycosides and in particular, flavonol 3-O-diglycosides. However, in members of the Myrtaceae, subfamily Leptospermoideae, the rare flavone aglycone tricetin, along with other flavonoid aglycones including 3-O-methyl quercetin and luteolin, have been found to comprise a significant portion of the constituent flavonoids.

The characterisation of New Zealand Podocarpus hybrids using flavonoid markers

Abstract New Zealand species of Podocarpus hybridise readily in the wild producing intermediate forms that are often difficult to identify. Flavonoid chemistry, in conjunction with morphological characters and geographical considerations, has proved to be of considerable value in the recognition of these natural hybrids. The parentage of Podocarpus totara var. wathoensis is confirmed, and the predominant parentage of P. totara “Aureus” is shown to be P. acutifolius X P. totara, and of P. totara “Pendulus” to be P acutifolius X P. nivalis. The probable parentage of other naturally occurring hybrids is also presented. The advantages of identifying the flavonoids over comparison of 2D paper chromatographic patterns alone are stressed. Flavonoid pattern variability of P. hallu is now thought to be caused by hybridisation, often with P. totara.

Leaf flavonoids of Actinidia

Abstract Leaf flavonoid chemistry of 22 taxa of Actinidia (Actinidiaceae) was studied. Flavonols predominated and the taxa studied were characterised by the presence of mono-, di- and in some cases, triglycosides. The taxa were distinguished from one another by their flavonoid profiles. Predominant glycosides were glucosides, galactosides, rhamnosides, rhamnoglucosides and rhamnogalactosides but not all glycosides were present in all taxa. C-Glycosylflavones were found in three species. Infrataxon variation was observed, e.g. A. polygama and A. arguta var. arguta. The genus has been subdivided on morphological grounds but large differences in flavonoid composition have shown up within all but one subdivision (Leiocarpae Series Solidae). It is shown that flavonoid composition can be used to confirm the parentage of putative hybrids.

A flavonol triglycoside from Actinidia arguta var. Giraldii

In the course of a chemotaxonomic study of the genus Actinidia a new flavonol triglycoside, quercetin 3-O-beta-D-[2G-O-beta-D-xylopyranosyl-6G-O-alpha-L-rhamnopyranosyl] glucopyranoside was identified amongst the 15 flavonols found in Actinidia arguta var. giraldii. This compound was characterized, along with quercetin 3-O-beta-D-xylopyranosyl-(1-2)-O-beta-D-glucopyranoside, by 1H and 13C NMR spectroscopy. The kaempferol analogues were also isolated.

Chemotypes of the Antarctic moss Bryum algens delineated by their flavonoid constituents

The flavonoid composition of Bryum algens from Antarctica is presented. It is shown that there exist two extreme patterns, with a range of intermediate forms. The patterns range from a flavonol dominant one, containing some flavone glycosides, through to a flavone dominant pattern essentially lacking flavonols. The close proximity of plants with different flavonoid profiles, and the presence of plants with intermediate patterns, suggest the existence of chemotypes within this species.

Peonidin 3-O-neohesperidoside and other flavonoids from Cyclamen persicum petals

Abstract The major anthocyanins and flavonols of two cultivars of Cyclamen persicum were characterised by 1 H- and 13 C-NMR spectroscopy. A previously unreported anthocyanin, peonidin 3- O -α- l -rhamnopyranosyl-(1-2)-β- d -glucopyranoside was isolated from C. persicum cv. Bonfire. The predominant anthocyanins isolated from C. persicum cv. Sierra Rose were the 3,5-di- O -glucosides of peonidin, cyanidin and malvidin. Quercetin 3- O -2 G -rhamnosylrutinoside was isolated from both cultivars as the major flavonol.

Support from flavonoid glycoside distribution for the division of Dacrydium sensu lato

Abstract The flavonoid glycoside chemistry of all New Zealand, and a number of key non-New Zealand, representatives of Dacrydium sensu lato is reported for the first time. These data give strong support to the proposed segregation of Lepidothamnus and Halocarpus from Dacrydium. Lepidothamnus is characterised by a predominance of flavone O-glycosides in its foliage, and Halocarpus by a predominance of flavone C-glycosides. The flavonoid glycoside characteristics of the other segregate genera, Lagarostrobos and Dacrydium sensu stricto are less distinctive, both groups being characterised by a predominance of flavonol O-glycosides. It is also noted that Lagarostrobos colensoi of New Zealand and the non-New Zealand Dacrydium species do not fit comfortably with the respective type species Lagarostrobosfranklinii and Dacrydiun cupressinum in terms of their flavonoid glycoside chemistry. These two genera therefore need further consideration and definition.