Abstract
Chemical fractionation of Brickellia paniculata methanolic extract by monitoring its inhibitory effect on K(+)-induced contraction in guinea-pig ileum in vitro led to the isolation of 5,4'-dihydroxy-6,7,8-trimethoxyflavone (xanthomicrol) and the labdane-diterpene 3 alpha-angeloyloxy-2 alpha-hydroxy-13,14 Z-dehydrocativic acid (AAHDD). Both compounds inhibited the tonic contraction the effect being highly potent when a mixture in a proportion of 3 : 1 (xanthomicrol/AAHDD) was assayed. The phasic component of the contractile response with K(+) was also reduced by the compounds. Xanthomicrol depressed the spasms induced with ACh, Hist, and BaCl(2) and its effect on Ca (2+) concentration-response curve showed a type of non-surmountable calcium blocking action; unlike the flavonoid, AAHDD produced a parallel rightward shift of the concentration-response curve to calcium, suggesting a competitive antagonism with an estimated pA(2) of 4.66. Obtained results support, in part, the popular use of B. paniculata as a spasmolytic remedy.
Publication types
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Letter
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Research Support, Non-U.S. Gov't
MeSH terms
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Acetylcholine / pharmacology
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Animals
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Asteraceae*
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Barium Compounds / pharmacology
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Calcium / pharmacology
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Chlorides / pharmacology
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Diterpenes / pharmacology
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Flavones*
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Flavonoids / chemistry
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Flavonoids / isolation & purification
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Flavonoids / pharmacology*
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Guinea Pigs
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Histamine / pharmacology
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Ileum / drug effects*
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In Vitro Techniques
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Muscle Contraction / drug effects*
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Muscle, Smooth / drug effects
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Naphthalenes / chemistry
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Naphthalenes / isolation & purification
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Naphthalenes / pharmacology*
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Pentanoic Acids / chemistry
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Pentanoic Acids / isolation & purification
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Pentanoic Acids / pharmacology*
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Plant Extracts / chemistry
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Plant Extracts / isolation & purification
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Plant Extracts / pharmacology
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Potassium Chloride / pharmacology
Substances
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3-angeloyloxy-2-hydroxy-13,14-dehydrocativic acid
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Barium Compounds
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Chlorides
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Diterpenes
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Flavones
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Flavonoids
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Naphthalenes
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Pentanoic Acids
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Plant Extracts
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labdane
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barium chloride
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xanthomicrol
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Potassium Chloride
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Histamine
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Acetylcholine
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Calcium