Phytochemical Analysis And Bioactivity Evaluation Of Standardized Extracts Of Mitragyna Speciosa And Pharmacokinetics Of Mitragynine
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Date
2010-10
Authors
Parthasarathy, Suhanya
Journal Title
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Publisher
Universiti Sains Malaysia
Abstract
The pharmacology of M. speciosa leaf extracts and mitragynine in rats were investigated. Two new High Performance Liquid Chromatography Ultraviolet HPLC –UV analytical methods were developed and validated for assay of mitragynine in M. speciosa leaf extracts and plasma. Both HPLC-UV method for assay of mitragynine in plant matrix and plasma yield a clean chromatogram, short analysis time, good assay sensitivity and was successfully used for their intended applications. The first HPLC-UV method was used to standardize water , methanolic and alkaloid extracts of M. speciosa leaf which was subsequently used for antimicrobial and antioxidant studies. The second HPLC-UV method with SPE extraction techniques for plasma sample clean up was employed to determined the mitragynine pure compound pharmacokinetics in rats. The mitragynine (MG) content in alkaloid rich fraction, methanol extract and water extract were 23 , 4.4 and 0.7% respectively . The method was found equally applicable to determine mitragynine in decoction M. speciosa leaf (50-180μg/mL) obtained from the streets. The antioxidant properties of M. speciosa leaf extracts were determined using standardized extracts.The total phenolic content of the aqueous, alkaloid and methanolic extracts were 66.0 mg, 88.4, 105.6 mg GAE/g, respectively, while the total flavonoid were 28.2, 20.0 and 91.1 mg CAE/g respectively The aqueous, alkaloid and methanolic extracts were further screened for antimicrobial activity for selected microorganism. The minimum inhibitory concentrations of this extracts determined by the broth dilution method ranged from 3.12 to 6.25 mg/mL. The results suggest that the methanolic extract showed relatively high antioxidant activity whereas as for the bioactive analysis, alkaloid rich fraction was found to be most effective against all of the tested organisms in comparison to other extracts. The mitragynine pharmacokinetics was investigated in rats after oral and intravenous administration of mitragynine. After intravenous administration mitragynine demonstrated biphasic elimination from the plasma with a mean half-life of 2.9±2.1 h. The oral absorption of mitragynine was slow, erratic and eliminated with prolonged half-life of 6.6±1.3 h .The calculated absolute oral bioavailability of mitragynine was 3.03 %. The variations observed in previous pharmacokinetic studies after oral administration of mitragynine could be attributed to its poor bioavailability rather than to the differences in assay method, metabolic saturation or mitragynine dose.
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Keywords
Phytochemical analysis and bioactivity evaluation of standardized extracts , of mitragyna speciosa and pharmacokinetics of mitragynine