Biomedical subjects
T H Althuis
Publications and source records attributed to T H Althuis.
Potent analgetics derived from 9-nor-9 beta-hydroxyhexahydrocannabinol.
Based on the report of morphine-like analgetic activity of 9-nor-9 beta-hydroxyhexahydrocannabinol (HHC), we undertook a study of structural modifications of the C-3 side chain of HHC to optimize the analgetic activity. We ultimately examined four distinct classes of side chains: (1) alkyl (la-lc), (2) arylalkyl (ld-lh), (3) alkoxy (li-lj) and (4) arylalkyloxy (lk-lo). Three of these derivatives (lb, lf, ll) possessed analgetic activity 10X morphine. These studies demonstrate that the C-3 side chain of HHC can be modified in a structure-dependent fashion to yield potent, nonopioid analgetics. In addition, the effect of the 1 methyl-4-phenylbutyloxy side chain is unique among the side chains examined.
Structure--activity relationships in a series of novel 3,4-dihydro-4-oxopyrimido[4,5-b]quinoline-2-carboxylic acid antiallergy agents.
A series of more than 50 new 3,4-dihydro-4-oxopyrimido[4,5-b]quinoline-2-carboxylic acid derivatives and related compounds with substituent variations at the 2, 3, and 5--9 positions was prepared and evaluated for antiallergy activity using the rat PCA assay. These compounds were obtained by the condensation of the appropriately substituted 2-aminoquinoline-3-carboxamides with dialkyl oxalates, followed by further chemical transformations. More than two-thirds of the compounds prepared exhibited intravenous activity ranging from 1 to 400 times disodium cromoglycate (DSCG). Structure--activity data suggest that the presence of a carboxylic acid moiety at the 2 position affords optimal potency and that esters are preferred for good oral absorption. Best oral activity, with ED50 values ranging from 0.3 to 3.0 mg/kg, was displayed by ethyl esters with methoxy and/or ethoxy groups at the 7 and 8 positions.
Development of ethyl 3,4-dihydro-4-oxopyrimido[4,5-b]quinoline-2-carboxylate, a new prototype with oral antiallergy activity.
Structural modification of 3,4-dihydro-4-oxoquinazoline-2-carboxylic acid leading to ethyl 3,4-dihydro-4-oxopyrimido[4,5-b]quinoline-2-carboxylate, a new prototype with oral antiallergy activity of the disodium cromoglycate type, is described. This prototype is 10 times more potent than disodium cromoglycate in the rat passive cutaneous anaphylaxis test. Structure-activity studies indicate that a carboxylic acid moiety directly attached to the 2 position of the pyrimidine ring is most favorable for intravenous activity while esters of this acid are preferred for oral activity. The oral activity of ethyl 3,4-dihydro-4-oxopyrimido[4,5-b]quinoline-2-carboxylate (ED50 = 3 mg/kg) places this ester among the more potent orally active antiallergy agents reported to date.
Synthesis and identification of the major metabolites of prazosin formed in dog and rat.
The 6-O-demethyl and 7-O-demethyl analogues of the new antihypertensive drug prazosin [2-[4-(2-furoyl)-piperazin-1-yl]-4-amino-6,7-dimethoxyquinazoline hydrochloride] have been unequivocally synthesized via separate ten-step reaction sequences starting from isovanillin and vanillin, respectively. The 6-O-demethyl derivative was found to be identical with the major prazosin metabolite formed in dog and rat, while the 7-O-demethyl derivative was identical with another, less prevalent but significant metabolite. Two minor metabolites of prazosin, 2-(1-piperazinyl)-4-amino-6,7-dimethoxyquinazoline and 2,4-diamino-6,7-dimethoxyquinazoline, are also described. All four metabolites are less potent blood pressure lowering agents in dogs than prazosin but may contribute to its antihypertensive effect, since they account for a major portion of the administered dose.
Selective and potent analgetics derived from cannabinoids.
Based on the hypothesis that analgetic activity is a dissociable feature of the cannabinoid molecule, we examined modifications of the side chain, the phenolic moiety, and, most significantly, structures that lack the benzopyran functionality present in THC and (--)-9-nor-9 beta-hydroxyhexahydrocannabinol (HHC). A new grouping, the 1-methyl-4-phenylbutyloxy C-3 side chain, elaborates a unique lipopholic region. Replacement of the phenol substituent produced several derivatives which retain analgetic activity in the codeine potency range. Introduction of a weakly basic nitrogen at C-5 and deletion of the axial methyl group in the B ring, two structural changes forbidden by traditional cannabinoid SAR, resulted in a unique family of benzoquinolines with potent analgetic activity. The prototype of this series, levonantradol, exhibits potent and stereospecific analgetic and antiemetic activity.