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Equivalent sweetness to varying levels of sucrose was determined for naringin dihydrochalcone (ND), neohesperidin dihydrochalcone (NHD), hesperetin dihydrochalcone glucoside (HDG) and aspartylphenylalanine methyl ester (AP). The effect of sucrose and these compounds at equivalent sweetness levels on thresholds of limonin and naringin was determined. HDG was the most effective compound and sucrose the least effective in raising the threshold or suppressing bitterness of both limonin and naringin. At 1% sucrose equivalence, limonin thresholds were increased 0,40, 150 and 220% for sucrose, NHD, AP and HDG, respectively. At 5% sucrose equivalence, naringin thresholds were increased 80, 90, 145 and 180% by AP, sucrose, NHD and HDG, respectively.

A sensory panel of experienced judges was used to determine taste thresholds of mixtures of limonin and naringin and various sweeteners. Data from these experiments showed that within the 95% confidence interval, subthreshold interactions between limonin and naringin were additive, indicating that less than threshold amounts of these compounds contributed to bitterness of a mixture. Mixtures of hesperetin dihydrochalcone glucoside (HDG), neohesperidin dihydrochalcone (NHD), naringin dihydrochalcone (ND), sucrose and naringin were neither additive nor synergistic at subthreshold concentrations. At suprathreshold levels, sucrose, (HDG) and (NHD) were effective in suppressing naringin bitterness, but (ND) was not.

Some dihydrochalcones and related flavonoids were tested Cor their effects upon indoleacetic acid oxidase (mainly from pea roots) and upon oxidative phosphorylation in mitochondria from cucumber hypocotyls. Also their influence upon the growth of wheat roots and upon the absorption of 14C-labelled sugars and 2, 4-dichloro-phenoxyacetic acid in wlieat roots was studied. The dihydrochalcone glucoside phloridzin known for its strong inhibitory effects upon sugar transport in some animal tissues gives no corresponding specific effects in higher plants. Phloridzin and some related dihvdrochalcone glycosides as well as the structurally similar compounds naringenin and 2′, 4, 4′-trihydroxychalcone are potent stimulators of indoleacetic acid oxidase. Sieboldin, which compared to phloridzin has an additional hydroxyl group (giving an ortho-diphenolic substitution in the B-ring) is a strong inhibitor of indoleacetic acid oxidase (10−6M gives about 50 per cent Inhibition). Phloridzin and sieboldin replace each other in different groups of species in the genus Malus. The aglycones phloretin, naringenin and 2′, 4, 4′-trihydroxychalcone stimulate wheat root growth (especially in the presence of auxins or growth-inhibilory sugars) and inhibit the absorption of sugars and of 2, 4-dichlorophenoxyacetic acid. They also inhibit oxidative phosphorylalion and give a distinct uncoupling effect. The glycosides are as a rule less active in all these respects and sieboldin is almost inactive. There is a rather good correlation between uncoupling of oxidative phosphorylation and effects upon root growth, whereas there is no agreement in the details between the effects upon root growth and upon IAA oxidase.

SUMMARY— The sensory and stability properties of neohesperidin dihydrochalcone were evaluated. Combinations of neohesperidin dihydrochalcone with saccharin and cyclamate were tested for their effect on taste qualities in soft drink type products. A mixture in which neohesperidin dihydrochalcone contributed 25% of the total sweetness (saccharin 64% and cyclamate 11%) gave a taste sensation that was considered to be of good quality. Tests indicated that the presence of neohesperidin dihydrochalcone gave, for most tasters, an apparent increase in flavor. The ethoxy homolog, homoneohesperidin dihydrochalcone, gave the same effect as the neohesperidin dihydrochalcone. The stabilities of neohesperidin dihydrochalcone under a variety of conditions of manufacture, storage and use were studied. Research showed that the glycosidic compound was resistant to hydrolysis of the sugar moieties in solutions of various acids above pH 2 at normal temperatures.

The transformation of monophenolic compounds to their ortho -dihydroxy analogues by the action of phenolase has been studied for enzyme sources from Malus , Pyrus and a few other plants. Dihydrochalcone glycosides of phloridzin type appear to be the most effective in vitro substrates for phenolase, even when these compounds do not occur in the plant concerned. Examination of a few plants selected at random indicates that the ability to hydroxylate phloridzin must be quite widespread in the plant kingdom. The flavonone naringenin is hydroxylated in much greater yield by phenolase from Pyrus rather than Malus leaves. Although dihydrochalcones are hydroxylated with equal facility by both blossom and leaf phenolases from Pyrus , in the case of naringenin it is only the leaf phenolase which exhibits any appreciable activity. Flavonoids of the flavone, flavonol and dihydroflavonol classes are not transformed to any appreciable extent as compared with the dihydrochalcones. Both the absolute and relative effectiveness of p -coumaric and 3-O- p -coumaroylquinic acids as phenolase substrates was found to be dependent upon the nature of tissue within the plant from which the enzyme was extracted.

7-Hydroxyflavylium salts dimerize in aqueous acetic acid solutions to form benzopyrylium salts substituted at position 4 with the corresponding dihydrochalcone nucleus. It is proposed that this dimerization involves initial condensation of the flavylium salt and its carbinol base to give a product which then undergoes a series of intermolecular hydride ion transfer reactions. It is also suggested that flavones are formed as by-products in these flavylium dimerization reactions.

Summary Individual steps in the reduction of chalcone at the dropping mercury electrode are expressed by scheme (A)−(U). The product of the first two-electron step is dihydrochalcone; in the second, alcohol is formed. Reduction of dihydrochalcone is governed by the rate of its general acid-base catalysed formation from the carbanion-enolate which is the primary electrolytic product. In the first one-electron step, an organomercury compound is formed. Reduction processes are accompanied by antecedent and interposed proton, transfers. For the protonation of the radical anion, [ArCO-CHCHAr] (•) , resulting in the chalcone reduction, an approximate value, p K 6 =10.2 was found and for that of the radical anion, [ArCOCH 2 CH 2 Ar] (•) , resulting in the dihydrochalcone reduction, an approximate value, p K 9 =8.75 was found. Radical anions react with alkali metal cations, but the waves of ketyls formed are not separated from those of radicals, resulting in analogous reactions with dydronium ions. The importance of using results obtained with controlled-potential electrolysis by means of a dropping mercury electrode rather than with a mercury pool electrode, for elucidation of polarographic processes, was stressed.

Double bonds in some αβ-unsaturated ketones are reduced by propan-2-ol in the presence of soluble iridium–sulphoxide catalysts. Chalcone gives (2-benzoyl-1-phenylethyl-O)dichlorobis(dimethyl sulphoxide)iridium as a crystalline intermediate, which is converted into dihydrochalcone on treatment with acids.

1. A study was made of the hydrogenation rate of chaleone in aqueous dioxane solution at electrodes with a variable hydrogen overvoltage. 2. At a Pt/Pt electrode the process proceeds by an electrocatalytic mechanism with the formation of dihydrochalcone. The dimeric product is formed at Hg and poisoned Pt electrodes.

Investigations were performed on the correlation between the inhibitory power on Na+, K+-ATPase activity of phlorizin, asebotin, coreopsin, naringin-and hesperidin-chalcone and their chemical structure. Both chalcone and dihydrochalcone inhibited Na+, K+-ATPase activity, depending upon the number and position of phenolic hydroxyl group in their carbon skeleton. Free hydroxyl group at 4' position of phlorizin played an important role in the inhibitory power.

Problèmes nouveaux des boissons diététiques à jus de fruits. Saveur sucrée, corps sucrés utilisables, développement des édulcorants, sucres pour aliments de régime, édulcorants synthétiques (cyclamates, dulcine, saccharine, p4000, s23-46, dihydrochalcones), édulcorants naturels (acides aminés, glycyrrhizine, stevioside, perillartine, extraits végétaux nouveaux), produits améliorants (nucleotides, miraculine, maltol)

The subfamily Pomoideae has been surveyed for leaf phenolics and it has been shown that flavone glycosides are present in the genera Sorbus, Aronia, Chaenomeles and Hesperomeles in addition to the previously reported occurrences in Crataegus, Malus and Pyrus . The dihydrochalcone phloridzin, a typical constituent of Malus , has also been found in Docynia . Arbutin and phenolic acid-calleryanin esters are apparently restricted to Pyrus . Naringenin and eriodictyol glucosides have been detected in Pyracantha, Sorbus, Photinia, Chaenomeles and Hesperomeles . A number of Pomoideae phenolics have been found in two Spiraeoideae genera; luteolin 7-glucoside,] luteolin 7-diglucoside, luteolin 7-rhamnosylglucoside and apigenin 7-glucoside in Exochorda and the dihydrochalcone trilobatin in Sorbaria . The chemotaxonomic evidence is consistent with the hypothesis that the Pomoideae evolved through a process of allopolyploidy from primitive members of the Spiracoideae and Prunoideae.

Boiling acetic anhydride and sodium acetate is shown to convert (�)- dihydro-quercetin tetramethyl ether into (α,2?-diacetoxy-3,4,4?,6?- tetramethoxychalcone, the first chalcone derivative to be isolated from base-catalysed ring fission of a dihydro-flavonol. 7,3?,4?- Trimethoxydihydroflavonol under similar conditions gave the 3-acetate as the only characterizable product, so that a methoxylated phloroglucinol-type A ring appears necessary for fission of a dihydroflavonol to the corresponding chalcone diacetate. The dihydrochalcone obtained by hydrogenation of α,2?-diacetoxy-3,4,4?,6?- tetramethoxychalcone was also prepared by unambiguous synthesis in nine stages from phloroglucinol (33% over-all yield), and was converted in low yield by N-bromosuccinimide into α,2?-diacetoxy-3?(or 5?)-bromo- 3,4,4?,6?-tetramethoxychalcone. Infrared and nuclear magnetic resonance data are recorded for the compounds described.