Kinetic studies of the spasmogenic effects of serotonin and isolates from Byrsonima crassifolia leaves on rat fundus
type: CreativeWork
description: Leaf and bark extracts of a Mexican medicinal plant, Byrsonima crassifolia (Malpighiaceae), exhibited spasmogenic effects on isolated rat fundus and biphasic effects on jejunum and ileum. Preliminary evaluations using rat fundus in Krebs solution indicated that the activity of a 2% acetic acid extract of eaves (HOAcE) could be split into two types: (i) high-efficacy, low-potency, n-butanol-extracted, pargyline- and 1-(1-naphtylpiperazine) (1-NP)-sensitive, atropine-insensitive activity, and (ii) low-efficacy, high-potency, ethyl acetate-extracted, pargyline-insensitive, atropine- and 1-NP-sensitive activity. HOAcE lacked muscarinic and nicotinic effects on rat jejunum and frog rectus abdominis. Serotonin (5-HT) and HOAcE curves in fundus were parallel and 5-HT potency was 6,037 times that of HOAcE (95% confidence limits: 4,624-7,852). The pD2 (affinity constant) for 5-HT was 7.96 (7.92-8.00) with pargyline added to the medium. 5-HT receptor-interaction kinetics using cholinergics and 5-HT agonists and antagonists was carried out. 1-NP competitively antagonized 5-HT. The 5-HT, antagonist s-(-)propranolol did not significantly antagonize 5-HT. The 5-HT2 blocker ketanserin noncompetitively antagonized 5-HT and α-Me-5-HT (pD'2 = 5.6 and 6.7, respectively). The 5-HT3 antagonist MDL-72222 inactivated only a small proportion of receptors (pD'2 = 6.46). Atropine did not significantly modify the curve of 5-HT while fluoxetine noncompetitively antagonized 5-HT (pD'2 = 5.8). 5-HT and α-Me-5-HT curves were biphasic indicating two receptor interactions (high and low affinity). High-affinity pD2 values for six different 5-HT agonists and 1-NP on rat fundus correlate well with reported rat brain (radioligand binding) pKd values at the 5-HT1C receptor (r = 0.94). Large scale extraction and fractionation of a methanol extract of leaves yielded two peaks of activity (Peak 1, lipophilic; Peak 2, polar). Peak 1 contained Compounds 1 to 7 (C1-C7); Peak 2 included C8-C15. Compound 1, C2,…
abstract: Leaf and bark extracts of a Mexican medicinal plant, Byrsonima crassifolia (Malpighiaceae), exhibited spasmogenic effects on isolated rat fundus and biphasic effects on jejunum and ileum. Preliminary evaluations using rat fundus in Krebs solution indicated that the activity of a 2% acetic acid extract of eaves (HOAcE) could be split into two types: (i) high-efficacy, low-potency, n-butanol-extracted, pargyline- and 1-(1-naphtylpiperazine) (1-NP)-sensitive, atropine-insensitive activity, and (ii) low-efficacy, high-potency, ethyl acetate-extracted, pargyline-insensitive, atropine- and 1-NP-sensitive activity. HOAcE lacked muscarinic and nicotinic effects on rat jejunum and frog rectus abdominis. Serotonin (5-HT) and HOAcE curves in fundus were parallel and 5-HT potency was 6,037 times that of HOAcE (95% confidence limits: 4,624-7,852). The pD2 (affinity constant) for 5-HT was 7.96 (7.92-8.00) with pargyline added to the medium. 5-HT receptor-interaction kinetics using cholinergics and 5-HT agonists and antagonists was carried out. 1-NP competitively antagonized 5-HT. The 5-HT, antagonist s-(-)propranolol did not significantly antagonize 5-HT. The 5-HT2 blocker ketanserin noncompetitively antagonized 5-HT and α-Me-5-HT (pD'2 = 5.6 and 6.7, respectively). The 5-HT3 antagonist MDL-72222 inactivated only a small proportion of receptors (pD'2 = 6.46). Atropine did not significantly modify the curve of 5-HT while fluoxetine noncompetitively antagonized 5-HT (pD'2 = 5.8). 5-HT and α-Me-5-HT curves were biphasic indicating two receptor interactions (high and low affinity). High-affinity pD2 values for six different 5-HT agonists and 1-NP on rat fundus correlate well with reported rat brain (radioligand binding) pKd values at the 5-HT1C receptor (r = 0.94). Large scale extraction and fractionation of a methanol extract of leaves yielded two peaks of activity (Peak 1, lipophilic; Peak 2, polar). Peak 1 contained Compounds 1 to 7 (C1-C7); Peak 2 included C8-C15. Compound 1, C2,…
author: Béjar, Ezra
keywords: Byrsonima crassifolia, Serotonin, Pharmacognosy, Medicine and Health Sciences, Pharmacy and Pharmaceutical Sciences
license: http://rightsstatements.org/vocab/InC/1.0/
date published: 1991-01-01T08:00:00Z
date modified: 2026-07-24T05:36:28Z
provider: University of the Pacific
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of the Pacific