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Sympathomimetic effects of Scoparia dulcis L. and catecholamines isolated from plant extracts.

Abstract

The herb Scoparia dulcis L. is used in Brazilian folk medicine to treat bronchitis, gastric disorders, haemorrhoids, insect bites and skin wounds, and in oriental medicine to treat hypertension. A previous study has shown that extracts of S. dulcis have analgesic and anti-inflammatory properties; in this work the sympathomimetic activity of an ethanolic extract of Scoparia dulcis L. has been investigated in rodent preparations in-vivo and in-vitro. Administration of the extract (0.5-2 mg kg-1, i.v.) to anaesthetized rats produced dose-related hypertension blocked by the alpha-adrenoceptor antagonist prazosin (1 mg kg-1). Partition of the extract in chloroform-water yielded an aqueous phase 20 times more potent than the extract; this produced hypertension in either reserpine-treated or pithed rats. In untreated and reserpine-treated rats the same fraction (1-3 x 10(3) micrograms mL-1) produced concentration-dependent contractions of the vas deferens musculature parallel to those obtained with noradrenaline (10(-8)-10(-4)M). Prazosin (10(-7)M) reduced the maximum contractile effect of the aqueous fraction, and shifted the concentration-response curves for noradrenaline to the right. The aqueous fraction (25 and 50 micrograms mL-1) increased the inotropism of electrically driven left atria of rats, the effect being blocked by propranolol (0.4 microgram mL-1). In preparations of guinea-pig tracheal rings the aqueous fraction (1-3 x 10(3) micrograms mL-1) relaxed the muscle contraction induced by histamine (10(-4) M) in proportion to the concentration. The effect was antagonized competitively by propranolol (1.5 microM). High-performance liquid-chromatographic analysis of the aqueous fraction revealed the presence of both noradrenaline and adrenaline in the plant extract. The results indicated that both catecholamines may account for the hypertensive and inotropic effects obtained after parenteral administration of S. dulcis extracts. This sympathomimetic activity is, however, unrelated to the previously reported analgesic and anti-inflammatory properties of the plant extract, but may explain its effectiveness upon topical application in the healing of mucosal and skin wounds.

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  • Authors+Show Affiliations

    ,

    Universidade Federal de São Paulo, Escola Paulista de Medicina, Department of Pharmacology, São Paulo, SP, Brazil.

    , ,

    Source

    MeSH

    Analgesics
    Animals
    Anti-Inflammatory Agents, Non-Steroidal
    Blood Pressure
    Brazil
    Catecholamines
    Chromatography, High Pressure Liquid
    Guinea Pigs
    Heart Atria
    In Vitro Techniques
    Male
    Mice
    Muscle Contraction
    Muscle, Smooth
    Plant Extracts
    Plants, Medicinal
    Rats
    Rats, Wistar
    Sympathomimetics
    Trachea
    Vas Deferens

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    8832498

    Citation

    Freire, S M., et al. "Sympathomimetic Effects of Scoparia Dulcis L. and Catecholamines Isolated From Plant Extracts." The Journal of Pharmacy and Pharmacology, vol. 48, no. 6, 1996, pp. 624-8.
    Freire SM, Torres LM, Souccar C, et al. Sympathomimetic effects of Scoparia dulcis L. and catecholamines isolated from plant extracts. J Pharm Pharmacol. 1996;48(6):624-8.
    Freire, S. M., Torres, L. M., Souccar, C., & Lapa, A. J. (1996). Sympathomimetic effects of Scoparia dulcis L. and catecholamines isolated from plant extracts. The Journal of Pharmacy and Pharmacology, 48(6), pp. 624-8.
    Freire SM, et al. Sympathomimetic Effects of Scoparia Dulcis L. and Catecholamines Isolated From Plant Extracts. J Pharm Pharmacol. 1996;48(6):624-8. PubMed PMID: 8832498.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Sympathomimetic effects of Scoparia dulcis L. and catecholamines isolated from plant extracts. AU - Freire,S M, AU - Torres,L M, AU - Souccar,C, AU - Lapa,A J, PY - 1996/6/1/pubmed PY - 1996/6/1/medline PY - 1996/6/1/entrez SP - 624 EP - 8 JF - The Journal of pharmacy and pharmacology JO - J. Pharm. Pharmacol. VL - 48 IS - 6 N2 - The herb Scoparia dulcis L. is used in Brazilian folk medicine to treat bronchitis, gastric disorders, haemorrhoids, insect bites and skin wounds, and in oriental medicine to treat hypertension. A previous study has shown that extracts of S. dulcis have analgesic and anti-inflammatory properties; in this work the sympathomimetic activity of an ethanolic extract of Scoparia dulcis L. has been investigated in rodent preparations in-vivo and in-vitro. Administration of the extract (0.5-2 mg kg-1, i.v.) to anaesthetized rats produced dose-related hypertension blocked by the alpha-adrenoceptor antagonist prazosin (1 mg kg-1). Partition of the extract in chloroform-water yielded an aqueous phase 20 times more potent than the extract; this produced hypertension in either reserpine-treated or pithed rats. In untreated and reserpine-treated rats the same fraction (1-3 x 10(3) micrograms mL-1) produced concentration-dependent contractions of the vas deferens musculature parallel to those obtained with noradrenaline (10(-8)-10(-4)M). Prazosin (10(-7)M) reduced the maximum contractile effect of the aqueous fraction, and shifted the concentration-response curves for noradrenaline to the right. The aqueous fraction (25 and 50 micrograms mL-1) increased the inotropism of electrically driven left atria of rats, the effect being blocked by propranolol (0.4 microgram mL-1). In preparations of guinea-pig tracheal rings the aqueous fraction (1-3 x 10(3) micrograms mL-1) relaxed the muscle contraction induced by histamine (10(-4) M) in proportion to the concentration. The effect was antagonized competitively by propranolol (1.5 microM). High-performance liquid-chromatographic analysis of the aqueous fraction revealed the presence of both noradrenaline and adrenaline in the plant extract. The results indicated that both catecholamines may account for the hypertensive and inotropic effects obtained after parenteral administration of S. dulcis extracts. This sympathomimetic activity is, however, unrelated to the previously reported analgesic and anti-inflammatory properties of the plant extract, but may explain its effectiveness upon topical application in the healing of mucosal and skin wounds. SN - 0022-3573 UR - https://wwww.unboundmedicine.com/medline/citation/8832498/Sympathomimetic_effects_of_Scoparia_dulcis_L__and_catecholamines_isolated_from_plant_extracts_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0022-3573&date=1996&volume=48&issue=6&spage=624 DB - PRIME DP - Unbound Medicine ER -