J. M. van der Nat

Immunomodulatory activity of an aqueous extract of Azadirachta indica stem bark

The interference of an aqueous extract of the stem bark of Azadirachta indica with different parts of the human immune system was investigated. The extract showed strong anticomplementary effects which were dose-and time-dependent and most pronounced in the classical complement pathway assay. Moreover, a dose-dependent decrease in the chemiluminescence of polymorphonuclear leukocytes was observed and a dose-dependent increase in the production of migration inhibition factor by lymphocytes.

Ethnopharmacognostical survey of Azadirachta indica A. Juss (Meliaceae).

Literature data on respectively botany, chemistry, ethnopharmacology, pharmacology and toxicology of Azadirachta indica A. Juss. (Meliaceae) are reviewed and evaluated. In traditional literature, preparations of the tree are claimed to be vulnerable in wide spectrum of diseases. Especially for inflammation-related diseases a good correlation is found with the results of recent experimental investigations. In addition, a variety of other biological activities are reported. Most frequently the effects can be attributed to compounds representing the structural classes of the limonoids, phenolics and macromolecules. Reported toxicity of preparations and isolated compounds are low, except for the seed oil. In conclusion, A. indica can be regarded as a valuable plant source for the rationalisation of its use in traditional medicine and for modern drug development.

Characterization of anti-complement compounds from azadirachta indica

The crude aqueous extract of Azadirachta indica bark possesses an inhibitory activity on both classical (CP) and alternative pathway (AP) activation of human complement. Purification of the compounds with the guidance of the AP-inhibitory activity involved extraction with methanol, dialysis, ion-exchange procedures and gel-permeation chromatography. This sequence yielded two polymers, NB-I and NB-II, one a highly active compound with a relatively low molecular weight (NB-II) and the other a less active compound with a high molecular weight (NB-I). The polymers were characterized by using colour reactions, TLC, GLC and HPLC after hydrolysis and gel-permeation chromatography as peptidoglycans. The carbohydrate part consisted predominantly of glucose. Arabinose, galactose and mannose were present in minor amounts (NB-II) or only as traces (NB-I). Protein was present for 5.5% in NB-I and for 9.8% in NB-II.

Suppression of migration inhibition factor (MIF) production by mitomycins in vitro

The effects of a series of mitomycins in a modified version of the Migration Inhibition Factor (MIF) test were investigated. This modified assay, which uses monocytes of the mouse cell line WEHI3 as target cells for MIF, discriminates between effects on the migrating monocytes, the production of MIF by lymphocytes and the activity of the produced MIF. The 7-methoxy mitomycins were found to be more active than the 7-amino and 7-hydroxy derivatives in suppressing both the spontaneous migration of target monocytes and the MIF production by lymphocytes. Neither of the compounds had a significant effect on the activity of produced MIF. A relationship between the activities of the mitomycins and their lipophilicity and polarographic half-wave potential is discussed. Further attention is paid to the stability of the mitomycins under the test conditions and additional advantages of the modified MIF assay over related in vitro tests for cell-mediated immunity.