178
S. D. Shnyder and C. W. Wright
1 Introduction
Cryptolepine (5-methyl-10H-indolo[3,2-b]quinoline (1)) (Fig. 1) is the principal
indoloquinoline alkaloid found in the dried roots of the West African climbing shrub
Cryptolepis sanguinolenta (Lindl.) Schltr. (Apocynaceae) (Plate 1) [1], synonymous
with C. triangularis N.E.Br and Pergularia sanguinolenta Lindl. [2]. Although more
than 40 species of Cryptolepis are recognized [2], C. sanguinolenta is the only one
so far reported to contain 1. While this alkaloid has also been found in the aerial
parts of Indian Sida acuta Burm.f. (Malvaceae), the quantity was small (0.017% of
a basic extract) [3], and is much lower than the amount present in C. sanguinolenta
roots (ca. 1%) [1].
Fig. 1 Structures of
cryptolepine and
indoloquinoline isomers
N
N
1
4
5
6
9
1 0
11
1 (cryptolepine)
N
N
1a (cryptolepine, alternative form)
N
N
2 (neocryptolepine)
N
3 (isocryptolepine)
N
N
4 (isoneocryptolepine, synthetic)
N
Plate 1 Cryptolepis
sanguinolenta; photograph
courtesy Dr. Naalamle
Amissah, Department of
Crop Science, College of
Basic and Applied Science,
University of Ghana