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Planta Med 1999; 65(8): 690-694
DOI: 10.1055/s-1999-14043
Original Paper

Georg Thieme Verlag Stuttgart · New York

Antiplasmodial Activity of Extracts and Alkaloids of Three Alstonia Species from Thailand

Niwat  Keawpradub1, 3 , G.  C.  Kirby2 , J.  C. P. Steele2 , P.  J.  Houghton1
  • 1 Pharmacognosy Research Laboratories, Department of Pharmacy, King's College London, London, U.K.
  • 2 Department of Medical Parasitology, London School of Hygiene and Tropical Medicine, London, U.K.
  • 3 Permanent address: Department of Pharmacognosy and Pharmaceutical Botany, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Hat Yai, Songkla, Thailand
Further Information

Publication History

March 9, 1999

May 1, 1999

Publication Date:
31 December 1999 (online)

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Abstract

Methanol extracts prepared from various parts of Alstonia scholaris, A. macrophylla and A. glaucescens, collected from Thailand, have been assessed for antiplasmodial activity against multidrug-resistant K1 strain of Plasmodium falciparum cultured in human erythrocytes. Pronounced antiplasmodial activity was exhibited by methanol extract of the root bark of A. macrophylla with an IC50 value of 5.7 μg/ml. Thirteen indole alkaloids were isolated from the active extract. These alkaloids and a semisynthetic bisindole O-acetylmacralstonine were subsequently tested against the K1 strain of P. falciparum . Pronounced antiplasmodial activity was observed mainly among the bisindole alkaloids, particularly villalstonine and macrocarpamine with IC50 values of 0.27 and 0.36 μM, respectively. The potent alkaloids were further tested against T9-96, the chloroquine-sensitive strain of P. falciparum. It has been found that the active alkaloids, in contrast to chloroquine, have significantly higher affinity to the K1 strain than to the T9-96 strain.

Key words

Alstonia - Apocynaceae - indole alkaloids - Plasmodium falciparum - antiplasmodial activity

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