lsolated Guinea-Pig lleum

FABAD Farm. Bil. Do>r.

13, 326" 331, 1988

FABAD J. Pharın. Sci.

13, 326 - 331, 1988

Antispasmodic Actions Of

2-Alkylaminomethyl-Benzimidazole Dihydrochloride Derivatives On The

lsolated Guinea-Pig lleum

Yusuf ÖZTÜRK (*) İlhan IŞIKDAG (**) Ümit UÇUCU (**) Şeref DEMİRAYAK (**)

Suınınary: In t:his s:tudy, seventeen 2-alkylaroinomethyfbenzi-mida"

zole deTivatives were iın:vestiıgated on the isolated guinea-pig ileum for their effects on the oumulatıiıve dose-response curveıs of barium dhloride, methacholine and histamine. Antaıgonistic affini,ties of benzimidazole derivartives against the agonists were calculated for tlıe comparison of their effects on t:he guinea-pig ileum.

Key Words: Antispaısmodıic action, 2-alkylaminomethylbenzimidazo- les, ıbarium chloride, metıJıacholine, histamine, guinea-pig ileum,

2-ALKİLAMİNOMETİL-BENZİMİDAZOL DİHİDROKLORÜR TÜREVLERİNİN İZOLE KOBAY İLEUMUNDAKI

ANTİSPAZMODİK ETKİLERİ

Özet : Bu çalışmada, onyedi 2-alkilaminometil-benzimidazol türevi, izole kobay ileumunda baryum klorür, .m,etakolin ve histamin'ıin kümü- latif doz-yanıt eğrileri üzerine etkileri yönünden araştırılmıştır. Bu amaçla, benzimidazol türeıvlerinin barsak üzerindeki etkilerini karşı·

!aştırmak içıin antagonist afiniteleri hesaplanmıştır.

(*) Anadolu Unıiversity, Faculty of Pharmacy, Department of P.harma- cology, Eskişehir

(**) Anadolu University, Facul,ty of Pharmacy, Department of Pharma- ceutical Ohemistry, E·skişehir.

INTRODUCTION

'Benzimidazole derivatives pos- sess various biological actions.

2~Benzylbenzimridazole (Bendazol)

haıs antispasmodic and antihyper- tensive a:ctJivities (1). However, the mechanism of .these actions of 2-benzylbenZJimidazole is still unes- tabhshed. On the other hand, it has been reporıted that 2-alkylami- nornethyl-lbenzimidazoles have so- me -other plharmacological proper- ties such as antituberculous (2) and anticonvulsant (3) actions. In this study, we ai;med to investigate an- t,ispasmodi'c actions of seventeen

2-alkylaminomethyl-benzimidazole derivatives using cumulatiıve dose- response procedure on the isolated guinea-pig ileum.

MATERIALS AND METHODS Isolated Guinea-Pig Ileum

Isolated guinea-pig ileum was prepared in a manner consistent with the method described by Magnus (4). T'he terminal ^ıileuın pi, eces from guinea-pigs weighing 300 to 400 g were removed after k:illing and kept in Tyrode solution. Then, the pieces '\vere suspended in a 10-ml organ batlı filled witlı Tyro- de ¹solution at 37° and ,gassed with 5 o/o ·C02 in oxyıgen. The compositi- on of Tyrode solution was (in g/ml): NaCl 8.00, KG 0.20, MgC1₂ 0.10, NaH₂P0₄ 0.05, NaHC0₃ 1.00 and glucose 1.00.

The suspBnded ileum pıieces

were allowed to equilibrate far 60

ıninutes. During this periocl, the tissues were washecl-out eve:ry 15 minutes. After this initial incubat~·

on, cumulative dose-response rı:::la­

tionships were ob.tained according to Van Rossum and Van Den Brink (JS). Baııium chloride, met-

hacıholine and histamine were tes- ted as agonist in the presence and in tlıe abs·ence of 2-alkylamino-

ınetlıyl-benzimiclazoles. The isola- ted guinea-pig ileum was incubated with these compounds 10 minutes before testing. The incubation pe- riod used ıin this study was deter- mined experimentally.

The contraotions of .guinea-pig ileum were recorded on a smoked drum iby a frontal vrriting lever

\.Vith 5 times maJgnification. The lo- ad on the tissue was 1.0 g.

Analysis of Data

To evaluate the actions of an- taJgoni·sts on the guinea-pig ileum pD' ₂ and pA₂ values which are non- competitive and competiti:ve a-nta- gonist affinity constants were cal- culated according to Ariens and Van Rossum (6) and Schild (7), res- pectively.

All values reported show the mean ± S.E.M. of individual expe- riments. The cumulative dose-r-es, ponse curves obtained in the pre.

sence and in the absence of tlıe

benzi,midazole derivatives were analyzed by means of linea:r :reg- ression procedure.

Chemicals

2-alkylaminoınelhyl-benzimida,

zole derivati'Ves have been previo- usiy synthesized and their struc"

tures have been determined (8).

Table I shows th¹e general structu-

re of the coınpounds. Bariun1 ch1o,

ı1ide, nıethacholine and histamine vvere purchased from Merek, Sigma and BDH, respectively. All diluti- ons were prepared wjth frcsh Ty.

rode solution.

'fable I : 2-Alkylaminomethyl-benzimidazole Dihydrochloride (General Formula)

R=H, R'=NH2 (Comp. !), N(CH_{3) 2} (il), N(C₂H_{5) 2} (III),

ınorpholine (iV), piperidine (V), pyrrolidine (V!).

R=Me, R'=NH2 (Vll), N(C2H_{5) 2} (Vlll), morpholine (IX), piperidine (X), pyrrolicHne (XI).

R=Cl, R'=N(CH3 )2 {XII), morplıoline (Xlll), piperidıine (XIV).

R=N02 R'=NH₂ (XV), morpholine (XV!), piperidine (XVll).

RESULTS

2-Alkıylaminomethyl...,benzimida­

zoles inhibited the bari um c:hloride-,

nıethacholine- and hictamine-indu- ced contract:ions of the guinea-pig ileum. With the exception of com- pounds, V, VI and VIII, al! ^inlıibi·

tıions were non-competitive in na- ture (TaJble il). Compound V, VJ and VIII antagonized the histamine induced contractions in com.petiti- ve ınanner (Table III). Intestingly, compound VII potentiated the ^ınet­

hacholine-induced contractions, but anta.gonized the histamine- and ba·

rium chloride-induced contractions.

DISCUSSION

Barium chlorıide, methacholine and histamine are spasmogerıic

compounds. They cause contracti~

ons on 'Various smootıh ınuscle pre-

paııations. Among theıse prepara:ti- ons, isolated guinea-pig ileum is a sensitive bioassay organ for tes·

tinıg spasmogenic and antispasmo- genic compounds '(9). Methacholine and hristamine elicit contractions on the . .guinea-pig ileum via ·mus- carinic and H1 receptors, respecti- vely (10, il). On tlıe guinea-pig ileum, barium chloride acts as a spasmogenic compound \.Vhose mec

Table il : Non-competitive antagonist aftinity constants for 2-alkyla- minomethyl-benzimidazoles on the isolated guinea-pig ileıun

(pD'₂ values calculated according to Ariens and Van Ros- sum, 1957). The values rep'res·ent mean ± SEM (n=6).

Compound Bacı, Methacholine Histamine

~ ---·---

I 3.98 ± 0.02 2.18 ± 0.04 3.85 ± 0.05

il 4.07 ± 0.09 2.85 ± 0.02 3.76

±

0.42

III 3.27 ± 0.08 3.33 +- 0.09 3.65

±

0.07

ıv 4.29 ± 0.10 3.13 +- 0.09 3.85

±

0.09

vıı 2.84 ± 0.11 None¹ 2.92

±

0.10

ıx 3.35 + o.ıs 3.88

±

^{0.14 2.87}

±

^0.09

x

3.08 +- 0.05 3.23 +- 0.02 3.77

±

0.07

XI 3.41 +- 0.05 5.06 +- 0.10 4.89

±

0.11

xıı 3.00 +- 0.02 3.62 +- 0.04 4.15

±

^0.09

XIII 2.93 +- 0.05 3.27 +- 0.09 3.62

±

^0.06

XIV 4.91 +- 0.06 5.78 +- 0.04 5.25

±

0.09

xv

3.37 +- 0.06 3.55 +- 0.07 2.51

±

0.08

XVI 3.52 +- 0.21 3.68 +- 0.10 4.32

±

^0.24

xvıı 2.89 +- 0.19 3.67 ± 0.20 2.31

±

O.IS

1ıSince synergism was oıbserved for this compound, no value was caloulated.

Table ili : Antagonist affinlty constant for compounds V, VI and VIII

oıl' the isolated guinea-pig ilewn {pA₂ and pD' ₂ values calcuı~tled according to Ariens and Van Rossum, 1957 and Schild, 1947). The values repı:esent mean ± SEM (n=6).

Histamine

Compound pA₂ ±SEM

v

5.63 +- 0.09

vı 4.94 +- 0.09

vıı 3.74 +- 0.12

hanis-m of action İ'S not clearly elu·

cidated (12). It is wel! known that the actions of the spasmogenic substances on smooth muscles are

pD'₂ ±SEM pD'₂ ± SEM

Methacholine Bacı,

4.19 +- 0.12 4.24

±

^0.10

3.14 ± O.ü7 4.31

±

0.09 3.51 ± 0.09 3.30

±

O.ü7

inhıibited by non~specific antispas- modic c::ompound in non-com.peti-ti- ve manner. Papaıverine i,s a well- known exa·mple of non~specific an~

iispasn1odic agents, which has been found to inhi'bit fhe acetylchnline-, histamine- and barium chloride- induced contractı:ions (13).

The purpose of this study was to exam·ine the possiıble antispas- 1n1odic actions of 2-alkylaminomet,

hyl~benzimidazole deriıvatives on the guinea-pig ileum. All compo- unds, with the cxception of com- püunds V, VI and VIII, inhiıbited

the contractions of ıba:nium chlori- dc, met'hacholine and histamine in non-competiti-ve manner. This fin, ding st:rıOnglıy sugıgest rhat 2-alk:y,

lan1inomethyl_ıbenzimidazoles pos, s'ess ,non-specific antispasmodric acti- ons on the isolated quinea-pig ile- um. Among the.se compou·nds, XIV and XI are mosrt potent reıga:rding

to the antispasmodic action. It ^ap·

pears that the antispasmodic acti- ons of the benzimidazole deriva,

ti.ıves may occur with a com

mon non~specifüc mec¹hanism which is still unidentified. It would be of

·intereSt to exami'ne the underlying mec'hanism for the actions of these compounds.

Compounds, V, VI and VIII in·

hibited histamine-induced contrac- tions in competitive manner, while 1!hey antagonized the contraotions elicited by methacholine and ba- rium Chloride, non-competitively.

Therefore, it appears that these compounds may have a specıific an- tihistaminic a:ction on the guinea- pi'g ileum. Unfortunately, their an- tagonis'tic potenciıes extremely low when compared with mepyramine

whose pA2 values is about 9 against histamine in the same preparation.

T'he structure of these compounds are siınıilar to clemisole. Clemisole which İ's a clinically use.ful antihis~

taminic agent has a benzimidazo- le ring (14). Fur:fuer experiments should be performed in order tJ

confirm the proposal concerning 1he antihistaminic action of these compounds.

Although the .fündings obtai- ned in this study are unsatisfac- tory in terms of antispasmodic .potencies of these compounds, this study İ's a preliminary one which may ibe pioneering to future rese- arehes in this area.

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