Plants as sources of antimalarial drugs. Part 7. Activity of some species of meliaceae plants and their constituent limonoids

Abstract

Indian Neem tree is known for its pesticidal and medicinal properties for centuries. Structure elucidation of large number of secondary metabolites responsible for its diverse properties has been achieved. However, this data is spread over various books, scientific reports and publications and difficult to access. We have compiled and stored structural details of neem metabolites in NeeMDB, a database which can be easily accessed, queried and downloaded. NeeMDB would be central in dissipating structural information of neem secondary metabolites world over. Background: Neem tree (Azadirachta indica A. Juss), native to Indian sub-continent, has long been recognized for its pesticidal and medicinal properties[1, 2]. It has gained the distinction of being the most researched tree in the World. Extracts of neem fruit, seeds, seed kernels, twigs, stem bark and root bark have been shown to possess repellent, anti-feedant, insect growth regulatory (IGR), anti ovipositional, fecundity and fitness reducing properties on insects [3]. Many species of insects are known to be sensitized by neem formulations [3, 4]. Diverse biological properties of neem are due to many secondary metabolites found in various parts of the tree. Major constituents of its metabolite pool such as Azadirachtin, Azadirone, Gedunin, Meliacarpin, Nimbin, Salannin, Vilasinin groups were proved to be significant pesticidal and/or medicinal principle [5]. Crude extracts of neem are found to be more potent than pure Azadirachtin [6] suggesting there are many more compounds in the neem extract, which even at low concentration have potentiating abilities.

Antimalarial activity in crude extracts of some Cameroonian medicinal plants

“…Entandrophragma angolense is locally used in the treatment of malaria and some other diseases (Irvine, 1961;Obih et al, 1986;Bray et al, 1990). The stem bark, in aqueous decoctions, is used for the treatment of fever or malaria in Cameroon and Ivory Coast.…”

Novel Antimalarial Compounds Isolated in a Survey of Self-Medicative Behavior of Wild Chimpanzees in Uganda

“…In vitro antimalarial activities have recently been reported for limonoids from other Meliaceae: bark and seeds of Khaya grandifolia (2), bark of Khaya senegalensis (13), leaves of Azadirachta indica (11), and Cedrela odorata wood (3). The most active limonoid, gedunin, isolated from Khaya grandifolia, Cedrela odorata, and Azadirachta indica (3,16), had a better in vitro activity than chloroquine against clones sensitive to chloroquine (15). Its in vitro activity evaluated against a chloroquine-resistant strain of P. falciparum (IC 50 ϭ 0.72 g/ml) was roughly equivalent to that of trichirubine A (12), but its in vivo activity, initially poor (3), might be improved: for example, when combined with chloroquine (2), by synergism with dillapiol, a cytochrome P-450 3A4 inhibitor, or preparation of a more stable compound (16).…”

New antitrypanosomal tetranotriterpenoids from <i>Azadirachta Indica</i>

“…1 H and 13 C NMR data (Tables 1 and 2) showed resonances for four distinctive tertiary methyl groups δH 1.23 (H-19), 1.68 (H-18), 1.58 (H-29), 1.28 (H-30) on carbons at δC 16.4 (q), δC 12.8 (q), δC 17.1 (q), δC 17.5 (q), respectively. The positions of these methyl groups were assigned by analysis of HMBC spectrum.…”

“…The biological activities of A. indica have been widely attributed to the presence of limonoids; modified triterpenes with or derived from a precursor with a 4, 4,8-trimethyl-17-furanylsteroid skeleton. Crude extracts of some of the limonoids constituents of the A. indica have been shown to exhibit antimalarial activities against chloroquine resistant K1 strain of Plasmodium falciparum (Bray et al, 1990). We now report the structures of three new limonoids that were isolated from the leaves of A. indica and their activities against T. b. rhodesiense.…”