State of knowledge: Histolocalisation in phytochemical study of medicinal plants.

BACKGROUND AND AIM: The renewed interest in medicinal plants has led us to examine more closely the usefulness of metabolite histolocalisation in screening work before any in-depth phytochemical studies. Indeed, this method is a histochemical technique allowing characterizing plant tissues constituents; and in particular metabolites of therapeutic interest, without destroying or altering as much as possible the studied plant material. This work aims at allowing us carring out a wide screening to highlight bioactive metabolites in plants studied from our rich university heritage collection. MATERIAL AND METHODS: The histochemical characterisation used in our work is a chemical, morphological and topographical (localisation) technique that uses precipitation reactions using dyes, among others. To do this we made thin cross-sections using razor blades on fresh plant material. The sections were then coloured using conventional chemical stains and observations were made using a MOTIC BA210 microscope equipped with a MOTICAM camera. RESULTS AND CONCLUSION: In view of obtained results, this technique, therefore, proves to be a useful screening and analysis method when applied in phytochemical studies on plants such as Datura stramonium, Peperomia obtusifolia, Cecropia obtusa, Orthosiphon aristatus and Vitex agnus castus. The obtained results confirm presence of sought metabolites, and allow their precise histological localisation. This will make extraction process more profiTable, simpler or even more ecological by avoiding waste.

Copper(II) interactions with non-steroidal anti-inflammatory agents. III--3-Methoxyanthranilic acid as a potential *OH-inactivating ligand: a quantitative investigation of its copper handling role in vivo.

Pharmacological activities of copper(II) complexes are a direct function of the nature of their ligands associated with the metal ion in vivo. Some of these, defined as *OH-inactivating ligands (G. Berthon, Agents Actions 39 (1993) 210-217), may act as specific "lures" for hydroxyl radicals at inflammatory sites and behave as pseudo-catalase-like agents. This property has been advanced for anthranilic acid (H. Miche, V. Brumas, G. Berthon, J. Inorg. Biochem. 68 (1997) 27-38). With a view to improve the chemical features required to render such inactive substances effective anti-inflammatory drugs through their association with copper(II), an in vitro investigation into copper(II) interactions with the anionic form of an anthranilic acid derivative, namely 3-methoxyanthranilate (Man), has been performed under experimental conditions pertaining in vivo. Copper(II)-Man complex equilibria have been determined using glass electrode potentiometry, then checked by UV-vis and mass spectrometries. Given the prime role of histidine as a copper(II) ligand in blood plasma, copper(II)-histidine-Man ternary equilibria have also been studied. Subsequent computer simulations of the distribution of copper(II) in the extracellular fluid revealed that Man can specifically mobilize Cu(II) ions under inflammatory conditions without affecting their distribution under normal physiological conditions. Thiobarbituric acid reactive substances (TBARS) tests conducted with respect to standardized copper-mediated Fenton-type reactions (P. Maestre, L. Lambs, J.P. Thouvenot, G. Berthon, Free Rad. Res. 20 (1994) 205-218) have shown that, like anthranilic acid, Man can effectively both increase the Fenton-like reactivity of copper and decrease the amount of TBARS detected in solution, i.e., act as a potential *OH-inactivating ligand.