Hydroxy acids, bitterness

XLI-XLIII) and the hydroxy-benzoic acids (XXXV-XXXVII) probably have the same tendency, but, up to the concentrations tested, the 4-derivatives are not sweet and the 2- and 3-derivatives are not bitter. 

Acetaminophen, U5P. Acetaminophen. Af-Acetyl-p-aminophcnol. 4-hydroxyacetanilide. APAP (Panado. Tem-pra. Tylenol, etc.), may be prepared by reduction of p-ni-trophenol in glacial acetic acid, acetylation of p-aminophenol with acetic anhydride or ketene. or from p-hydroxy-acetophenonc hydrazonc. It occurs as a white, odorless. slightly bitter crystalline powder. It is slightly soluble... 

Picrolicbenic Acid. 6-Hydroxy-2 -methoxy-2,4 dioxo-4,6 -dlpentylspi rofben zofuran-3 2H),T -[2,5jcyclo-hexadieneJ-5-carboxylic acid picrolichenin. C H O, md wt 442.49. C 67.85%, H 6.83%, O 25.31%. Bitter acidic principle of crustose lichen, Pertusaria amara (Ach.) Nyl., Pertusariaceae. Isoln Alms, Ann. Pharm. 1, 61 (1832). 

Other abietane derivatives with benzenoid ring C are among the active substances in some well-known medicinal herbs. The parent hydrocarbon (-)-8,l 1,13-abieta-triene occurs in the pine tree Pinus pallasiana (Pinaceae). (+)-Camosolic acid and the 20,7p-lactone (-olide) of its hydroxy-derivative referred to as camosol belong to the bitter substances of the oil of sage from Salvia camosa (Labiatae) and related species. (-)-Rosmanol, a 20,6p-lactone, is an antioxidant isolated from the leaves of rosemary Rosmarinus officinalis (Labiatae), which also contain camosol. 

A qualitative theory on the relationship between bitterness and chemical structures of bitter Rabdosia diterpenoids has been proposed 143). To be bitter a substance must have at least one bitter unit it consists of a hard acid and a hard base which are located within 1.5 A of each other so that intramolecular hydrogen-bonding is possible. Cleavage of this hydrogen bond and concomitant formation of a new hydrogen bond to the receptor site are responsible for bitterness 150). For instance, isodonal (71) which possesses an a-orientated 11-OH is very bitter, while trichodonin (70), its 11 P-epimer, is not. In bitter isodonal, the distance between the 11-hydroxy proton, the donor proton, and the 6-aldehydic oxygen, the proton acceptor, is ca. 1 A, while in tasteless trichodonin it is ca. 3 A. 

Caicium Pantothenate USP, FCC, Calcium pantothenate. See Calcium D-pantothenate Calcium D-pantothenate CAS 137-08-6 EINECS/ELINCS 205-278-9 Synonyms Calcium d(+)-N-(a,y-dihydroxy-p,p-dimethylbutyryl)-P-alaninate Calcium N-(2,4-dihydroxy-3,3-dimethyl-1-oxobutyl-p-alanine Calcium pantothenate d-Calcium pantothenate Calcium d-pantothenate N-(2,4-Di hydroxy-3,3-di methyl buty ryl-P-alan i ne calcium D-N-(2,4-Dihydroxy-3,3-dimethyl-1-oxobutyl-p-alanine, calcium salt Extro calcium pantothenate Pantothenate calcium Pantothenic acid, calcium salt Vitamin B Vitamin B, calcium salt Definition Calcium salt of pantothenic acid Empirical C19H34N2O10 Ca Properties Wh. powd., odorless, sweetish taste with si. bitter aftertaste stable in air sol. in water, glycerol insol. in alcohol, chloroform, ether m.w. 490.63 m.p. 170-172 C dec. 195-196 C Toxicology LD50 (oral, mouse) 10 g/kg, (IP, rat) 820 mg/kg, (IV, rat) 830 mg/kg mod. toxic by IP, subcut., and IV routes mildly toxic by ing. TSCA listed... 

Common sage and rosemary (see Table 8.32), plants of the Lami-aceae family, contain the diterpenes camosic acid, also known as rosmaricin (8-259), derived from ent-caurene, and bitter carnosol (picrosalvin, 8-260), which are potent antioxidants. Carnosic acid is a major component of fresh rosemary tops (1-2%), but is unstable and is enzymatically transformed into carnosol. These two diterpenoids represent about 15% w/w of plants haulm extracts and exhibit about 90% of extract antioxidant activity. Other transformation products of carnosic acid are rosmanol (7a-hydroxy derivative, 8-261), epirosmanol (7P-isomer, 8-262) and similar compounds. 

Certain bacterial strains prodnce bitterness in wine—a fact known since the time of Pasteur. Lactic acid bacteria make use of a glycerol dehydratase to transfonn glycerol into j0-hydroxy-propionaldehyde (Figure 5.8). This molecule is the precursor of acrolein, which is formed in wine by heating, or slowly during aging. The combination of wine tannins and acrolein, or its precursor, gives a bitter taste. 

Adhulupone or 2-(2-methylbutanoyl)-5,5-bis(3-methyl-2-butenyl)-3-hydroxy-2-cyclopentene-1,4-dione (199, Fig. 83) with molecular formula C21H30O4 has a pKyy value of 2.65 in methanol water 1 1. The quinoxaline derivative has a melting point of 95°C (9). The UV spectra are very similar to those of hulupone and cohulupone with absorption maxima at 277 nm in acidic methanol and at 253 nm and 322 nm in alkaline methanol The only differences in the H NMR spectrum, compared to the compounds mentioned, are due to the signals of the 2-methylbutanoyl side chain, which characterizes the ad -series of the hop bitter acids. The molecular ion at m/z 322 is the most intense ion in the mass spectrum. 

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