A collection of 10 accessions of fenugreek (Trigonella foenum-graecum L.), an annual legume, was grown during two summers at three plot locations in western Canada to assess whether genetic (accession) and environmental factors (site and year of production) influenced levels of diosgenin, a steroidal sapogenin. The 60 harvested seed samples, each analyzed by single determinations on three subsamples of defatted and dried seed material, were hydrolyzed by a microscale procedure in water containing 2-propanol (70%) and sulfuric acid (1 M). The extracts were analyzed by capillary gas chromatography with 6-methyldiosgenin as internal standard. Diosgenin levels from mature seeds ranged from 0.28 to 0.92% (28-92 microg/10 mg). Analysis of variance on combined diosgenin levels from the three sites and two years revealed that accession, accession x year, and site x year effects were significant for diosgenin content, whereas site, year, and site x accession effects were not. Four accessions, CN 19062, CN 19067, CN 19070, and CN 19071, were identified with high levels of diosgenin on the basis of the 2-year data set. In these accessions, mean levels of diosgenin plus yamogenin from seven site years were estimated at 0.70, 0.98, 0.84, and 0.87%, respectively.

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Branched oligonucleotides have recently emerged as attractive synthetic targets for the selective recognition of nucleic acids. [1] These molecules have the potential to act as sensitive diagnostic tools for the detection of DNA sequences, [1a,b] and can specifically bind single-stranded DNA/RNA (antisense/ antigene strategy). [1c±e] In addition, they can serve as model complexes for the elucidation of the structure and biological role of branched RNA molecules found in nature. [1a,d] In previous branched systems, the DNA strands were linked together through oligonucleotide or small organic-moleculebased vertices. [1, 2] We recently initiated research into the synthesis and properties of a new class of branched oligonu-cleotides, in which a transition metal acts as the vertex joining two parallel DNA strands. Transition metal centers come in a range of geometries, coordination numbers, and bond angles that are unavailable in carbon chemistry (e.g., octahedral, square planar, trigonal bipyramidal). By combining this varied coordination chemistry with the highly specific interactions of DNA, we expect that these branched metal ± DNA complexes will expand the repertoire of DNA structures to novel motifs. [3] This can be achieved both through their binding to single-stranded DNA and RNA, as well as their self-association and formation of DNA ™nanostructures∫. [2] In addition, the rich redox and luminescence properties of metal centers afford a sensitive marker for detecting and monitoring the association of these new structures.While many transition metal labeled oligonucleotides were reported recently, [4] the metal center is usually tethered as a pendant functional group on a DNA strand, and hence its geometry cannot influence DNA association. [5] Here we report the first synthesis of a transition metal linked branched oligonucleotide (1), in which the DNA strands run parallel to P N N Ru N N N N (CH 2 ) 6 N N (CH 2 ) 6 O O-5'-TTTTTTTTTT-3' O-P O O-5'-TTTTTTTTTT-3' O-O O 2+ 1each other and the geometry of the metal center can directly influence the orientation of these strands. Furthermore, we have studied the biological behavior of these branched complexes by hybridization to complementary DNA. Thermal denaturation experiments show the formation of novel transition metal linked DNA duplexes with a stability comparable to that of Watson ± Crick A/T duplexes. In the design of complex 1, two parallel (5'-3') oligonucleotide strands are linked to a cis-[(bpy) 2 Ru(imidazole) 2 ] 2 moiety through n-hexyl spacers (bpy 2,2'-bipyridine). The ruthenium moiety is both redox active and intensely luminescent, and it has been extensively used as a probe of electron transfer processes in proteins. [6] Our convergent solidphase strategy [7] for the preparation of ruthenium-linked parallel oligonucleotides is outlined in Schemes 1 and 2. This strategy starts with the generation of a ruthenium bisphosphoramidite branching complex 3. [8] The reaction of two molar equivalents of 1-(6-hydroxyhexyl)imidazole [9a] with cis-[(b...