(2E,4E)-N-(4-(1H-indol-3-yl)piperidin-1-yl)alkyl-5-(substituted phenyl)-2,4-pentadienamides as antiallergic agents with antihistaminic and anti slow-reacting substance (SRS) activities.

As an extension of our study aiming to discover a novel compound with dual activities against histamine and slow-reacting substance (SRS), we synthesized two types of indolylpiperidine derivatives, 3 and 4-20. Testing for in vivo antianaphylactic activity and for in vitro anti-SRS activity revealed that (2E,4E)-5-(3,5-dimethoxy-4-hydroxyphenyl)-N-(2-(4-(1H-indol-3-yl)+ ++piperidin-1- yl)ethyl)-2,4-pentadienamide (11) exhibited potent dual activities with ED50 = 0.89 mg/kg and IC50 = 1.43 microM, respectively. However, the plasma concentration of unchanged 11 was very low when administered orally in guinea pigs. This result can be explained by fast formation of a glucuronic acid conjugate.

Synthesis and structure-activity relationships of antiallergic N-[4-[4-(1H-indol-3-yl)piperidinoalkyl]-2-thiazolyl]alkanamides possessing both antihistaminic and anti slow-reacting substance (SRS) activities.

A series of N-[4-[4-(1H-indol-3-yl)piperidinoalkyl]-2- thiazolyl]alkanamide derivatives were synthesized and tested for in vivo antianaphylactic activity and in vitro anti slow-reacting substance (SRS) activity. Among the compounds synthesized, N-[4-[4-(1H-indol-3-yl)piperidinomethyl]-2- thiazolyl]propanamide (7) was the best balanced compound (antianaphylactic activity, ED50 = 0.92 mg/kg p.o.; anti-SRS activity, IC50 = 0.89 microgram/ml). Regarding the biological activities of 7, we ascribe the antianaphylactic activity to its potent antihistaminic activity and the anti SRS activity to the inhibition of 5-lipoxygenase.

Synthesis and pharmacological properties of N-[4-[4-(1H-indol-3-yl) piperidinoalkyl]-2-thiazolyl]alkanesulfonamides as novel antiallergic agents.

A number of N-[4-[4-(1H-indol-3-yl)piperidinoalkyl]-2- thiazolyl]alkanesulfonamides (8--21) were synthesized and evaluated for their preventive effects on systemic anaphylaxis in guinea pigs. Structure-activity analysis revealed that methane- and ethanesulfonamide derivatives having a one to three methylene tether between the piperidine and thiazole rings exhibited potent activity but the introduction of a substituent on the indole part reduced the activity. Administration (100 mg/kg p.o.) of the four compounds 8, 9, 12, 13, together with ketotifen, oxatomide, terfenadine and azelastine as reference compounds, to mice revealed that only compound 8 caused no significant increase of the sleeping time induced by hexobarbital. In addition, compound 8 (10 mg/kg i.v.) did not change the electroencephalogram in conscious rabbits. These results led to the selection of N-[4-[4-(1H-indol-3-yl)piperidinomethyl]-2-thiazolyl]methanesulfon amide (8, FK613) for further development as a novel antiallergic agent. Clinical evaluation of FK613 is now in progress.

Synthesis and antiinflammatory and analgesic properties of 2-amino-1H-benzimidazole and 1,2-dihydro-2-iminocycloheptimidazole derivatives.

2-Amino-1H-benzimidazoles (3) and 1,2-dihydro-2-iminocycloheptimidazoles (4) were synthesized and evaluated for antiinflammatory and analgesic activities. The compounds in the series 3 were synthesized via phenylthioureas (6) or 2-chloro-1H-benzimidazole (12). Most of 4 were synthesized by two methods. One was the reaction of carbodiimides (14) with 2-amino-2,4,6-cycloheptatrien-1-one (method A). The other was the reaction of guanidines (15) with 2-chloro-2,4,6-cycloheptatrien-1-one (method B). Some of the compounds 3 and 4 exhibited potent antiinflammatory and analgesic activities when compared to timegadine (1) or tiaramide hydrochloride (HCl) (17). It was of interest that 1-(2-benzothiazolyl)-2-cyclohexylimino-1,2-dihydrocycloheptimid azole (4e) showed superior analgesic activity to timegadine or tiaramide HCl (ED50 = 1.7 mg/kg p.o. in the acetic acid-induced writhing test, ED30 = 14.0 mg/kg p.o. in Randall-Selitto method) in spite of no effect on prostaglandin E2 synthesis.