Robert E. Lundin

C-glycosylflavones from Zea mays that inhibit insect development.

Abstract A new C-glycosylflavone isolated from corn silk inhibits the growth and development of the corn earworm, Heliothis zea. This new compound was shown to be a 2″-O-α- l -rhamnosyl-6-C-(6-deoxy-xylo-hexos-4-ulosyl)luteolin. Also found co-occurring in corn silk were minor amounts of the corresponding 6-C-glycosylated analogs of chrysoeriol and apigenin.

3,6-Nonadien-1-ol from Citrullus vulgaris and Cucumis melo

Abstract cis , cis -3,6-Nonadien-1-ol isolated from watermelon and previously from muskmelon by vacuum steam distillation-extraction, was identified by int

Identification of several components of isochlorogenic acid

Abstract “Isochlorogenic acid” has been shown to be a complex mixture of closely related compounds. Three of the major fractions have been purified and shown by NMR spectroscopy to be 4,5-dicaffeoylquinic acid, 3,4-dicaffeoylquinic acid and 3,5-dicaffeoylquinic acid. A fourth major fraction appears to be a mixture of the 3′-methyl ethers of 3,5-dicaffeoylquinic acid.

Trifoliol, a new coumestan from ladino clover

Abstract A new coumestan, C16H10O6, related to coumestrol, has been isolated from ladino clover. Degradation and synthesis of the compound established its structure as 3,7-dihyroxy-9-methoxy-6H-benzofuro[3,2,c][1]-benzopyran-6-one.

C-2 stereochemistry of naringin and its relation to taste and biosynthesis in maturing grapefruit

Abstract Circular dichroism and proton magnetic resonance spectroscopy can be used to determine the C-2 chirality of naringin, the main bitter principle of grapefruit. Thus, the aglycone chirality of naringin has been studied as a function of grapefruit maturity. The amount of (2 S ) isomer is 85–92% in immature grapefruit but only 55–60% in mature grapefruit. These results are discussed in relation to the current postulates relating to flavanone biosynthesis. A naringin sample predominant in the (2 R ) isomer has been prepared and found by some tasters to be more bitter than the (2 S ) naringin. It is concluded that the naringin isomerization in ripening grapefruit is not responsible for debittering.

Conformation analyses of D-(−)-quinic acid and some of its derivatives by nuclear magnetic resonance

Abstract D -(−)-Quinic acid, eight monoacyl esters, three diacyl esters, and 5-dehydroquinic acid have been examined by NMR spectroscopy and shown to exist in solution in a chair conformation with the carboxyl equatorial. The efiects of this conformation on chemical and physical properties are discussed.

Anthocyanidins and related compounds—XII : Tetramethylleucocyanidin-phloroglucinol and resorcinol condensation products

Abstract Crystalline phloroglucinol and resorcinol condensation products with 5,7,3′,4′-tetramethoxyflavan-3,4-diol have been prepared. The structures of these products have been confirmed by extensive analytical and nuclear magnetic resonance spectral measurements.Abstract Crystalline phloroglucinol and resorcinol condensation products with 5,7,3′,4′-tetramethoxyflavan-3,4-diol have been prepared. The structures of these products have been confirmed by extensive analytical and nuclear magnetic resonance spectral measurements.

Auraptenol, a coumarin compound in bitter (Seville) orange oil

Abstract 7-Methoxy-8-(2-hydroxy-3-methyl-3-butenyl)-coumarin has been isolated from bitter orange oil and named auraptenol. NMR spectra together with IR spectra and analytical data are presented as evidence of its constitution.

13C NMR SPECTROSCOPY OF PYRROLIZIDINE ALKALOIDS

Abstract The 13 C NMR spectra of nine pyrrolizidine alkaloids of the macrocyclic diester type, seven of the corresponding N -oxides and of the parent base retronecine have been recorded and the signals assigned. The 13 C NMR signals were found to be sensitive to structural variation in both the diester moiety and the heterocyclic ring system, providing useful information for structural elucidation, particularly when the 1 H NMR spectra may be difficult to interpret.

Simmondsin, an unusual 2-cyanomethylenecyclohexyl glucoside from Simmondsia californica

Simmondsin, a monoglucoside extracted from seeds of the jojoba plant (Simmondsia californica), has been shown to be 2-(cyanomethylene)-3-hydroxy-4,5-dimethoxycyclohexyl β-D-glucoside (1). Analysis of the n.m.r. spectra of this compound and its penta-acetate permits assignment of the stereochemistry as well as establishing the point of attachment of the glucose.