Isolation of mitraphylline from Uncaria tomentosa (Willd. ex Schult.) DC. barks and development of spectrophotometric method for total alkaloids determination in Cat's Claw samples

  • Phytochem Anal. 2020 Mar;31(2):262-272. doi: 10.1002/pca.2891.
Marcos Martins Gouvêa  1 ,  Breno Henrique Pusceddu  1 ,  Annibal Duarte Pereira Netto  1 ,  Carlos Augusto de Freitas Peregrino  2 ,  Elizabeth Valverde Macedo  2 ,  Samanta Cardozo Mourão  2 ,  Flávia Ferreira de Carvalho Marques  1
Affiliations
  • 1. Departamento de Química Analítica, Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista, s/n - 24020-141, Centro, Niterói, RJ, Brazil.
  • 2. Departamento de Tecnologia Farmacêutica, Faculdade de Farmácia, Universidade Federal Fluminense, Rua Mário Viana, 523 - CEP 24241-002, Santa Rosa, Niterói, RJ, Brazil.
PMID: 31769108 DOI: 10.1002/pca.2891
Abstract

Introduction: The usual quality control for Uncaria tomentosa (Willd. ex Schult.) DC. barks requires highly specific analytical standards and methods based on high-performance liquid chromatography (HPLC), which impacts the costs of the analytical process and the final products.

Objective: To obtain an analytical reference standard of mitraphylline by isolation from U. tomentosa barks and develop a spectrophotometric method for determination of total Alkaloids in samples of U. tomentosa.

Methodology: An alkaloid-enriched extract was obtained by acid-base partition and mitraphylline was selectively precipitated using an 80:20 v/v toluene/hexane solution. The compound was characterised by HPLC-UV/DAD (diode-array detector), mass spectrometry, UV-visible, infrared (IR) and 1 H- and 13 C-nuclear magnetic resonance (NMR) spectroscopy. Sample preparation for the spectrophotometric method consisted of an extraction with boiling methanol (3 × 10 mL, 15 min), followed by a strong cation exchange solid phase extraction (SCX-SPE) clean-up.

Results: Mitraphylline with a purity of 98% was isolated in 0.05% m/m yield. All characterisation results were in agreement with previous published data. The spectrophotometric method showed linear range between 0.40 and 20 μg/mL; limits of detection and quantification of 0.15 and 0.49 μg/mg, respectively; dispersion of results lower than 5% for repeatability and intermediate precision; statistically proven accuracy by comparison with reference values obtained by Soxhlet and an HPLC-UV/DAD method; and robustness in relation to sample mass extracted and extraction time.

Conclusion: The methods developed to obtain mitraphylline analytical standard from U. tomentosa barks and to determine total Alkaloids by spectrophotometry provided a cheaper and faster quality control alternative for U. tomentosa samples.

Keywords
Uncaria tomentosa (Willd. ex Schult.) DC; method validation; mitraphylline; spectrophotometry; total alkaloids.
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