Bilo Diallo

Immunodetection of artemisinin in Artemisia annua cultivated in hydroponic conditions

Abstract A highly specific and sensitive ELISA method was developed for the detection and semi-quantitative determination of artemisinin and its structurally related compounds in crude extracts of Artemisia annua. The antibodies were raised in rabbits using a 10-succinyldihydroartemisinin-BSA conjugate as immunogen. The peroxide linkage in the artemisinin molecule was critical in determining the antibody specificity. The working range of the assay was from 0.02 to 10 ng per assay. The cross-reacting material in crude plant extracts was evaluated by chromatographic methods combined with the immunoassay method. The distribution of artemisinin equivalents in five-week-old A. annua plants cultivated in hydroponic conditions was investigated. The highest artemisinin equivalent content (1.12% dry wt) was found in the leaves of the upper parts of the plant.

Interaction between dipyridamole and eudragit S

Amorphous solid dispersions of dipyridamole were prepared by the solvent method using Eudragit S and RL as carriers in order to obtain controlled release dosage forms. When Eudragit S was used the release of dipyridamole from the solid dispersion particles was inhibited at low pH, but remarkably improved at neutral or alkaline pH values which correspond to the pH of polymer dissolution. In contrast, the dissolution of the active drug in acidic media was neither slowed down nor delayed when Eudragit RL was used as the carrying polymer. The striking difference between the drug release profiles of the two coprecipitates seemed to be caused by some interaction between Eudragit S and dipyridamole. The mechanism of this interaction was further investigated using various spectroscopic methods (UV, infrared, 1H- and 13C-NMR). The existence of preferential hydrogen bonding between the carboxylic functions of the polymer and some of the nitrogen atoms of dipyridamole was clearly demonstrated.

High-speed countercurrent chromatography separation of taxol and related diterpenoids from Taxus baccata

Abstract Taxol and related taxane diterpenoids were isolated from pre-purified extracts of stem-barks of Taxus bacccata by HSCCC. The described method allowed to obtain a mixture of taxol and cephalomannine without any other interfering constituent and furthermore a partial separation of taxol (40 % of the total recovery) from cephalomannine. In addition, the HPLC and TLC separation conditions of these compounds for the semi-preparative and analytical purposes were improved. The proposed HSCCC method could be adapted to the scaling-up separation of taxol from vew material.

Antihepatotoxic Actions of Cochlospermum Tinctorium Rhizomes

The antihepatotoxic activity of the rhizomes of Cochlospermum tinctorium was investigated using carbon tetrachloride- and galactosamine-induced cytotoxicity in primary cultured rat hepatocytes. Because the methanol and ethanol extracts of C. tinctorium rhizomes exhibited antihepatotoxic effects, the former was fractionated in order to elucidate the active constituents. Polyphenol compounds (gallic and ellagic acids) were detected in the active fractions and may account for much of the antihepatotoxic activity. Carotenoids could also be implicated in the activity of the total extracts.

Further studies on the hepatoprotective effects of Cochlospermum tinctorium rhizomes

The hepatoprotective activity of the rhisome of Cochlospermum tinctorium was investigated using carbon tetrachloride toxicity on mouse and tert-butyl hydroperoxide in vitro induction of lipid peroxidation and hepatocyte lysis. Aqueous, hydro-ethanolic and ethanolic extracts showed significant dose-dependent hepatoprotective actions. The ethanolic extract showed a hepatoprotective activity at lower doses than silymarin. The ethanolic and hydro-ethanolic extracts exhibited remarkable effects against the induction of lipid peroxidation and hepatocyte lysis; the aqueous extract showed comparatively weaker effects. These differences were related to the chemical composition of the extracts. Among the identified constituents of the drug, phenolic and polyphenolic compounds (gallic and ellagic acids, ellagitannins, flavonoids), carotenoids, triterpenes could be related to the biological activity.

Apocarotenoids from Cochlospermum tinctorium

Abstract Seven carotenoids have been isolated from Cochlospermum tinctorium by means of countercurrent chromatography and HPLC. The two major constituents were identified by spectroscopic methods (UV-VIS, IR, 1 H NMR, 13 C NMR and EIMS) as 6-hydroxy-8′-apo-e-caroten-3-one-8′-oic acid (cochloxanthin) and 4,5-dihydro-6-hydroxy-8′-apo-e-caroten-

Triacylbenzenes and long-chain volatile ketones from Cochlospermum tinctorium rhizome

Abstract The composition of the volatile fraction from Cochlospermum tinctorium rhizome was investigated by GC and GC-MS; among 11 constituents detected, eight were identified as straight chain ketonic compounds. In addition, five triacylbenzenes were isolated from a petrol extract of the rhizome, separated by HPLC and identified by their spectral data.

Large Scale Purification of Apocarotenoids from Cochlospermum Tinctorium by Countercurrent Chromatography

Abstract Carotenoids are well-known for their instability so as usual analytical methods such as HPLC or preparative TLC applied to the separation of the constituents of Cochlospermum tinctorium failed to the isolation of pure pigments for further chemical characterization. Thus high-speed CCC using a horizontal flow-through coil planet centrifuge was used to conveniently and efficiently achieve this separation for quantities up to 500mg of the crude plant extract.

Effect of jasmonic acid on developmental morphology during in vitro tuberization of Dioscorea alata (L.)

A developmental morphology study was performed during different stages of in vitro yam microtuber formation on both hormone-free medium (HF) and medium supplemented with 10 µM of jasmonic acid (JA). The axillary protuberance, considered as the first morphological evidence for microtuber formation, became visible after one-week of culture in JA-medium and after three weeks of culture in HF-medium. In addition, the formation of the axillary protuberance in JA-cultures preceded the stem elongation, whereas in HF-medium stem elongation was visible before the formation of the axillary protuberance. Tuberization improvement in medium supplemented with JA is likely to be the result of morphogenetic modifications occurring during the early stages of microtuber formation. At the molecular level, 2D-PAGE analysis of HF- and JA-cultures allowed the identification of four differentially expressed polypeptides, including two putative pathogenesis-related proteins and one putative glutathione S-transferase. For JA-cultures, three additional differentially expressed polypeptides were identified.

Immunoaffinity chromatography for the sample pretreatment of Taxus plant and cell extracts prior to analysis of taxanes by high-performance liquid chromatography

The application of immunoaffinity chromatography for the purification of Taxus plant and cell extracts prior to the HPLC analysis is described. Polyclonal antibodies raised against 10-deacetylbaccatin III (10-DAB III), paclitaxels main precursor in plant, were characterised by enzymed-linked immunosorbent assay. Immunoglobulins from selected antisera were immobilised on CNBr-activated Sepharose 4B. The immunoaffinity column was used for the purification of plant and plant cell culture extracts prior to their analysis by HPLC. Immunoaffinity chromatography enabled the selective concentration of taxoids and enhanced sample clean-up.