13C NMR studies of some naturally occurring amentoflavone and hinokiflavone biflavonoids

The ¹³C NMR spectra of a range of amentoflavone and hinokiflavone biflavonoids are reported, most for the first time. Substituent shifts relating to the interflavonoid linkages and to specific methylation patterns are defined and appear to be of diagnostic value.     

The 13C NMR spectra of some rosane diterpenoids

The ¹³C NMR signals of rosenonolactone have been assigned utilizing the ¹³C-¹³C couplings in material obtained biosynthetically from sodium [1,2-¹³C₂] acetate.     

Syntheses of naturally occurring terphenyls and related compounds

Naturally occurring terphenyls and related compounds such as terferol and its corresponding quinone and phlebiarubrone were synthesized from 2,5-diphenyl-1,4-benzoquinone. According to the proposed biosynthetic pathway, chemical conversion of phlebiarubrone to ustalic acid, a toxic compound isolated from the poisonous mushroom, Tricholoma ustale, was examined to find a low-yield conversion to the ustalic acid dimethyl ester.     

Total synthesis of naturally occurring moracinflavan E and related compounds

A total synthesis of four flavans with a furan ring in different positions (1–4) was achieved successfully. The flavan was synthesized from flavanone by reduction and followed by deoxygenation steps. The synthesized compound 2 was confirmed as the naturally occurring moracinflavan E based on the comparison of their NMR spectral data.     

The 13C NMR spectra of some ent-18-hydroxykaur-16-enes

The ¹³C NMR spectra are reported for thirteen ent-18-hydroxykaur-16-enes and their value for determining the C-4 stereochemistry is discussed.     

Bioconversion of naturally occurring precursors and related synthetic compounds using plant cell cultures.

The nearly unlimited enzymatic potential of cultured plant cells can basically be employed for bioconversion purposes. Plant enzymes are able to catalyze regio- and stereospecific reactions and can therefore be applied to the production of compounds of pharmaceutical interest. Naturally occurring as well as related synthetic compounds may be used as precursors. A review of the current status of such bioconversions is given. It includes the performance of bioconversions by freely suspended and immobilized plant cells or enzyme preparations. In addition, the kinetic aspects of immobilized plant cells are discussed. Special attention is paid to the bioconversion of poorly or water insoluble precursors. Finally, a model scheme for the development of a commercially available drug, produced by bioconversion, and perspectives are discussed.     

13C NMR Analysis of some simple tetrahydroisoquinolines

¹³C NMR resonances of 15 simple tetrahydroisoquinolines have been assigned on the basis of chemical shift theory, ¹³C-¹H coupling constants     

Isolation and characterization of naturally occurring cyanogenic compounds

The literature dealing with the detection, isolation, purification and characterization of cyanogenic glycosides has been integrated with spectral and chemical data as well as other techniques from our laboratory to establish a method for the positive identification of glycosides of this type. The compounds are arranged into biosynthetically related groups (those derived from l-phenylalanine; l-tyrosine; l-leucine, l-valine; l-isoleucine; those with cyclopentene rings and pseudocyanogenic glycosides) and features of each of the above procedures are critically reviewed and spectral data for each group presented (IR, MS, UV and NMR). The NMR spectra of TMS ethers of cyanogenic glycosides have proven especially useful in chemical structure determination. This information is sufficient to permit identification of any of the 26 known glycosides as well as certain uncharacterized ones.     

A review of the genetic effects of naturally occurring flavonoids,anthraquinones and related compounds

Two classes of common phenolic plant pigments, the anthraquinones and the flavonols, contain many members mutagenic in the Salmonella/mammalian microsome assay. Several reports on the mutagenicity or other genetic or “carcinogenic” effects of these compounds have appeared in the literature or have been presented at various scientific meetings. The object of this review paper is to assess the present state of knowledge with respect to the genetic toxicity of these agents and their dietary intake and metabolic fate in man. Such information is necessary for formulating an assessment of genetic or carcinogenic risk to man posed by these agents.