K. T. D. de Silva

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.

Two functionally and chemically distinct immunomodulatory compounds in the gel of aloe vera

An aqueous extract of Aloe vera gel was analyzed guided by modulatory activity with regard to the in vitro activation of human complement and of human polymorphnuclear leucocytes (PMN). Upon ultrafiltration a high (h-Mr) and a low (l-Mr) molecular mass fraction were obtained. Pre-incubation of human pooled serum with the h-Mr fraction resulted in a depletion of classical and alternative pathway complement activity. In contrast, only the l-Mr fraction could inhibit the production of free oxygen radicals by activated PMNs. The latter activity cannot be attributed to non-specific effects like toxicity, interference with stimulant binding or scavenger activity.

Imunodulatory compounds from Picrorhiza kurroa: Isolation and characterization of two anti-complementary polymeric fractions from an aqueous root extract

Two aqueous root extracts of Picrorhiza kurroa, one prepared by extraction at 4 degrees C and the other by refluxing, were purified using the guidance of modulation of classical (CP) and alternative (AP) pathway complement activity. By means of methanol extraction and gel filtration chromatography, two polymeric fractions were isolated from the cold water extract. A methanol-soluble polymeric fraction (CS1) was highly active in inhibiting CP complement activity exclusively, whereas a methanol-insoluble polymeric fraction (CI1) exhibited an inhibitory effect on both CP and AP complement activity. Preliminary chemical analysis of the anti-complementary fractions revealed the presence of structures of carbohydrate and of peptide nature in CS1 and CI1. The modulation of CP complement activity by CS1 was studied in more detail. Its inhibitory effect was proven to be based on complement consumption rather than on chelation of Ca2+ and/or Mg2+ or on stabilization of the target cells in the complement-assay. The purification of the aqueous extract prepared by refluxing, resulted in the isolation of a polymeric fraction with the same qualities as CS1. However, a fraction with properties similar to CI1 could not be isolated from this extract.

Nb-demethylalstophylline oxindole an oxindole alkaloid from the leaves of Alstonia macrophylla

Abstract An oxindole alkaloid, N b -demethylalstophylline oxindole has been isolated from the leaves of Alstonia macrophylla . Its structure has been elucidated on the basis of spectroscopic studies.

Immunomodulatory activity of three Sri-Lankan medicinal plants used in hepatic disorders

The effects of aqueous extracts of Osbeckia octandra whole plant, Melothria maderaspatana whole plant and Phyllanthus debelis leaves on the human immune system were investigated. The extracts showed strong anticomplement effects on both the classical and alternate pathways of the human complement system in vitro. The effects were dose-dependent and most pronounced in the classical complement pathway assay. The extracts also exhibited a direct dose-dependent inhibition of luminol-induced chemiluminescence of human polymorphonuclear leukocytes upon stimulation with zymosan.

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.

Isolation and structural studies on the alkaloids of Petchia ceylanica

Abstract (19 R )-Epimisiline and (19 S )-epimisiline, two new Aspidosperma alkaloids, have been isolated from the leaves of Petchia ceylanica . The structures have been deduced on the basis of chemical and spectroscopic data.