What's the difference between dextrorotatory and racemic?
Dextrorotatory
Definition:
(a.) Turning, or causing to turn, toward the right hand; esp., turning the plane of polarization of luminous rays toward the right hand; as, dextrorotatory crystals, sugars, etc. Cf. Levorotatory.
Example Sentences:
(1) The dextrorotatory enantiomer of fluoxetine was slightly more potent than the levorotatory enantiomer in antagonizing the depletion of brain serotonin by p-chloroamphetamine in rats.
(2) The dextrorotatory morphinan opioid, dextrorphan, which has recently been reported to block the excitation of cortical neurons by N-methyl-D-aspartate, was found at 10-100 microM concentrations to attenuate both morphological and chemical evidence of glutamate neurotoxicity in murine neocortical cell cultures; a similar effect was found with its methyl ester derivative, dextromethorphan.
(3) The differences in antihypertensive activity of racemic and dextrorotatory propranolol cannot be explained by different plasma levels; the data indicate that the hypotensive effect of propranolol is due to beta receptor blockade.
(4) Subsequently, beta-End and levorphanol (10(-8) M), but not the dextrorotatory isomer, stimulated an elongation of the cells.
(5) It is dextrorotatory, [alpha](D) = +138 degrees , and has a pK(a) of 5.1.
(6) A compound, C14H24O2, which induces strong juvenilizing effects in the yellow mealworm, Tenebrio molitor L., following topical application to the pupal stage, was isolated in pure form from the roots of Echinacea angustifolia DC and tentatively identified as dextrorotatory (E)-10-hydroxy-4,10-dimethyl-4,11-dodecadien-2-one.
(7) In hypertensive patients, whose blood pressure was decreased by racemic propranololthe dextrorotatory isomer had no antihypertensive effect.
(8) The dextrorotatory enantiomer prevented the depletion of brain serotonin at any time after p-chloroamphetamine.
(9) The dextrorotatory enantiomer of aminoglutethimide is 38 times more potent than the levoenantiomer in inhibiting aromatization of testosterone by human placental microsomes.
(10) In a separate experiment, 100 micrograms of dextrorotatory and levorotatory gossypol was administered to male mice.
(11) The [3H]Tol2Gdn binding site displays stereoselectivity for dextrorotatory optical isomers of benzomorphan opiates known to have sigma-type behavioral effects.
(12) Fatty acids esterifying these fatty alcohols in M. marinum and M. ulcerans were found to belong to the phthioceranic series (dextrorotatory fatty acids), in contrast to those of the other species (laevorotatory fatty acids called mycocerosic acids), both groups having the same chain length and methyl-branched positions.
(13) The dextrorotatory gossypol, both in rat and mice, had less pronounced effect on the histoarchitecture of the testis in comparison to racemic and levorotatory gossypol.
(14) The non-narcotic dextrorotatory morphinan, dextrorphan, as well as its levorotatory opioid enantiomer, levorphanol, and its O-methyl derivative, dextromethorphan, have recently been shown to antagonize N-methyl-D-aspartate receptor-mediated neurotoxicity.
(15) Contrary to what is generally accepted, the dysphoric and psychotomimetic side effects of sigma opiates are mediated by the levo-and not by the dextrorotatory isomers.
(16) Increases in ventricular myocardial refractoriness and in QTc and paced QT intervals suggest that class III electrophysiologic actions contribute to the antiarrhythmic properties of dextrorotatory sotalol in this animal model.
(17) When dog urine was heated with acid rather than treated with beta-glucuronidase, the isolated p-HPPH contained a small preponderance of the dextrorotatory isomer, probably owing to production of d-p-HPPH from the dihydrodiol metabolite.
(18) The dextrorotatory and levorotatory isomers of chloroquine did not differ in their ability to stimulate the hydrolysis of tRNA by pancreatic ribonuclease A.
(19) The others were the dextrorotatory 2,6-bis-(3',4'-dihydroxyphenyl)-3,7-dioxabicyclo-[3,3,0]-octane 4,8-dione (dehydrodicaffeic acid dilactone) andits antipode.
(20) Another mu-agonist, levorphanol (20, 40, 80, or 160 micrograms) and dextrorphan (160 micrograms), its dextrorotatory isomer, were used next to evaluate opioid specificity.
Racemic
Definition:
(a.) Pertaining to, or designating, an acid found in many kinds of grapes. It is also obtained from tartaric acid, with which it is isomeric, and from sugar, gum, etc., by oxidation. It is a sour white crystalline substance, consisting of a combination of dextrorotatory and levorotatory tartaric acids.
Example Sentences:
(1) These results indicate that both racemic and L-baclofen inhibit trigeminal transmission in man, probably because they interfere with excitatory transmission through the interneurons of the lateral reticular formation.
(2) In contrast to the enantiomeric discrimination observed with racemic amine, the individual isomers were metabolized at approximately the same rate.
(3) Routine enantiomeric analyses were successfully carried out on samples taken from animals dosed orally with the racemic drugs, providing important data on the possible levels of exposure to individual enantiomers during toxicity testing.
(4) Racemic verapamil and the L- and D-isomer increased cellular vincristine accumulation to the same extent.
(5) By this method, about 5.0 mg of racemic HCZ could be resolved completely in one run.
(6) The racemization-suppressing effect of other compounds were also evaluated by employing one of these model couplings to be at best only limitedly effective.
(7) The antihypertensive and pulse-slowing effects of racemic propranolol, oxprenolol, pindolol, practolol and d-propranolol were assessed in 54 hypertensive patients.
(8) The assay is reliable to 0.1% racemate with a detection limit of approximately 100 pmol.
(9) The allene oxide also opens to a zwitterion, which undergoes charge delocalization to form a planar intermediate; this structure is the achiral precursor of the stable end product of pericyclic ring closure, viz., racemic cis-12-oxo-PDA.
(10) Decreasing the water concentration in the reaction medium by adding methanol at 0 degrees C drastically reduces the rate of racemization without affecting the rate of transamination.
(11) Racemization of aspartic acid in dentin protein during the human lifetime progresses with age.
(12) Five diammine-Pt(II) or Pt(IV) coordination compounds, namely cis-diammine-dichloro-platinum (II) "cis-DDP", transdihydroxy-cis-diammine-dichloro-platinum (IV) "trans-ODDP", and derived substitution products of lactic acid (racemates or L-forms) with diminished toxicity in comparison to cis-DDP have been tested against mouse leukemia P388, and partly on melanoma B16 for antineoplastic activity.
(13) The racemic drug has unusual pharmacokinetic properties because of its concentration-dependent binding to plasma proteins in the therapeutic plasma concentration range.
(14) The vasodilating potency of d-alprenolol and d-propranolol was not significantly different from that of the respective racemic mixtures.
(15) High-pressure liquid chromatographic (HPLC) methods have been developed for the determination of drug content, racemate A and related compounds in nadolol raw materials.
(16) The effects of the d- and l-isomers of pentazocine were compared to that of racemic pentazocine on contractions of the mouse isolated vas deferens.
(17) Our results indicate that racemic EM 12 as well as its enantiomers are chemically and metabolically more stable than thalidomide; however, extensive racemisation occurs both in vivo and in vitro.
(18) These data, coupled with the equilibrium fractionation factor for the 2-position of proline (which has been determined to be 1.17), provide the transition-state factors for each of the in-flight protons, and delineate the nature of the transition state(s) for the enzyme-catalyzed racemization.
(19) Consequently, racemic compounds showed approximately half potency of the corresponding enantiomers.
(20) S(+)-ibuprofen and R(-)-ibuprofen given alone more rapidly reached significantly higher maximal plasma concentrations than after the same doses of the racemic compound.