Bronchodilator activity of Phymatodes scolopendria (Burm.) Ching and its bioactive constituent.

Phymatodes scolopendria (Burm.) Ching (Polypodiaceae) is widely used in the Eastern coast of Madagascar to treat respiratory disorders. Bioassay-guided fractionation using guinea pig trachea pre-contracted with histamine to monitor the activity led to the isolation of 1,2-benzopyrone (coumarin) as the main active constituent. Effectively, it induced a concentration-dependent relaxation of the histamine with a median effective concentration (EC(50)) of 35.03 microg/ml, or carbachol (EC(50) = 33.41 microg/ml) pre-contracted guinea pig trachea, and also provoked 100% relaxation at 72.10 microg/ml. It was less active either on KCl pre-contracted trachea (EC(50) = 130.78 microg/ml) or endothelium denuded trachea (153.4 +/- 22 microg/ml). It inhibited, in a non-competitive manner, the histamine and the external calcium spasm effect on the isolated trachea but it did not significantly modify the broncho-constrictive activity of KCl. When combined with theophylline, coumarin produced a significant additive relaxing effect on pre-contracted trachea. Furthermore, its bronchodilator effect was not blocked by propranolol. In vivo, pre-treated guinea pig with coumarin showed significant resistance to histamine inhalation, with an adequate dose protecting 50% of the tested animals (AD(50)) of 75 mg/kg. These results indicate that the bronchodilator effect of coumarin is partly due to the endothelium-dependent tracheal relaxation, and may be mediated through a non-specific tracheal relaxation.

Decreasing clinical efficacy of chloroquine in Ankazobe, Central Highlands of Madagascar.

The clinical efficacy of chloroquine was assessed in the Primary Health Centre of Ankazobe, Central Highlands of Madagascar. This study shows an increase in the level of chloroquine resistance with the appearance of early treatment failures and RIII resistance. Furthermore, the prevalence of clinical treatment failures is approaching the level of 25%, at which WHO recommends a change of first-line drug.

7-Epimer oxindole alkaloids of Cabucala cryptophlebia: their (13)C-NMR and CD data.

The isolation, (13)C-NMR and CD data of two 7-epimer oxindole alkaloids, 10,11-dimethoxyisomitraphylline (1) and 10,11-dimethoxymitraphylline (2) from Cabucala cryptophlebia are reported.

A new diterpene from Hypoestes serpens.

From a defatted chloroform extract of the aerial parts of Hypoestes serpens a new diterpene exhibiting relaxant activity on isolated rat aorta was obtained. The structure of this compound, named serpendione (1), was fully established by the interpretation of its spectral data.

The co-occurrence of C(3) epimer Nb,C(21)-secocuran alkaloids in Strychnos diplotricha and Strychnos myrtoides.

From the stem bark of Strychnos diplotricha, three Nb,C(21)-secocuran alkaloids, viz., 3-epi-myrtoidine, 11-demethoxy-3-epi-myrtoidine and 11-demethoxy-12-hydroxy-3-epi-myrtoidine, were isolated together with the known myrtoidine and 11-demethoxymyrtoidine. They also occur in different parts of S. myrtoides.

Biological activities of the plant-derived bisindole voacamine with reference to malaria.

The in vivo antiplasmodial activity of voacamine was assessed in a 4-day test. It was shown to exhibit in vivo activity with 25.4% and 43.4% inhibition of parasitaemia with 2.5 and 10 mg/kg, respectively. In synchronized cultures, it was found to act on trophozoite and schizont stages of Plasmodium falciparum. Using the FMC29 strain of Plasmodium falciparum as parasite and the isobologram curve as a method to assess interaction in drug combination, it was shown to lack any chloroquine-enhancing activity and its in vitro antiplasmodial effect was not potentiated by the chemosensitizer malagashanine.

Modulation of the multidrug-resistance phenotype by new tropane alkaloid aromatic esters from Erythroxylum pervillei.

Nine tropane alkaloid aromatic esters (1-9) were isolated from the roots of Erythroxylum pervillei by following their potential to reverse multidrug-resistance with vinblastine-resistant oral epidermoid carcinoma (KB-V1) cells. All isolates, including seven new structures (3-9), were evaluated against a panel of human cancer cell lines, and it was found that alkaloids 3 and 5-9 showed the greatest activity with KB-V1 cells assessed in the presence of vinblastine, suggesting that these new compounds are potent modulators of P-glycoprotein. Confirmatory results were obtained with human ovarian adenocarcinoma (SKVLB) cells evaluated in the presence of adriamycin and synergistic studies performed with several cell lines from the NCI tumor panel. The structures of the new compounds were determined using spectroscopic techniques. Single-crystal X-ray analysis was performed on the monoester, tropane-3 alpha,6 beta,7 beta-triol 3-phenylacetate (1).

Isolation from rat urine and human liver microsomes and identification by electrospray and nanospray tandem mass spectrometry of new malagashanine metabolites.

Malagashanine has been isolated from indigenous madagascan Strychnos myrtoides alkaloids used traditionally to treat malaria. This alkaloid was found to enhance the action of chloroquine against chloroquine-resistant strains of Plasmodium falciparum when combined with classical antimalarial drugs (chloroquine, quinine). The present study was carried out in order to investigate by electrospray mass and tandem mass spectrometry and NMR spectroscopy the structure of two new metabolites isolated from rat urine and human liver microsomes. We were able to demonstrate the presence of two new metabolites of malagashanine corresponding to a malagashanine N-demethylated metabolite and to the oxidation of malagashanine in the alpha-position of the N-methyl group to produce a carbinolamine function. The latter metabolite may be subject to ring and open-chain tautomerism effects and dimeric species were detected in the electrospray mass spectrum.

Spectral characterisation and antiplasmodial activity of bisbenzylisoquinolines from Isolona ghesquiereina.

From stem barks of Isolona guesquiereina three known bisbenzylisoquinolines were isolated and identified as (-)-curine, chondrofoline and isochondodendrine. Structures were established mainly on the basis of comparison of their physical and spectral data with published data for them and their methylated derivatives. Cleavage with sodium in liquid ammonia was necessary to unambiguously determine the stereochemistry of (-)-curine and subsequently establish its stereochemical link with chondrofoline, erroneously assigned as 7-O-methyl-(+)-curine. Complete and unambiguous 1H-, 15N- and 13C-NMR assignments of the three alkaloids were made by means of 2D-NMR techniques namely, COSY, HMQC, gs-HMQC, HMBC and NOESY. (-)-Curine, isochondrodendrine and their methylated derivatives were shown to exhibit strong in vitro antiplasmodial activity and in vivo activity was also observed for (-)-curine.

High-performance liquid chromatographic assay of malagashanine in rat plasma and urine and its pharmacokinetic application.

A reversed-phase HPLC method was developed for quantitative analysis of malagashanine in rat plasma and urine. Malagashanine and internal standard were extracted from alkalinized rat plasma. Urine analysis was performed by direct injection onto the HPLC system. Acetonitrile-aqueous 25 mM sodium acetate solution at pH 6.25 (45:55, v/v) was used as the mobile phase. The eluate was monitored by using UV detection at 250 nm. The assay was linear within the concentration range of 10-1000 ng/ml. Both intra- and inter-day accuracy and precision were within acceptable limits. The method was applied to study the pharmacokinetics of malagashanine in rats.

Reversal activity of the naturally occurring chemosensitizer malagashanine in Plasmodium malaria.

Malagashanine (MG) is the parent compound of a new type of indole alkaloids, the N(b)C(21)-secocuran, isolated so far from the Malagasy Strychnos species traditionally used as chloroquine adjuvants in the treatment of chronic malaria. Previously, it was shown to have weak in vitro intrinsic antiplasmodial activity (IC(50) = 146.5 +/- 0.2 microM), but did display marked in vitro chloroquine-potentiating action against the FcM29 chloroquine-resistant strain of Plasmodium falciparum. The purpose of the present study was to further investigate its reversal activity. Thus, the previous in vitro results were tested in vivo. The interaction of MG with several antimalarials against various strains of P. falciparum was also assessed. As expected, MG enhanced the effect of chloroquine against the resistant strain W2, but had no action on the susceptible strain 3D7 and two sensitive isolates. Interestingly, MG was found to exhibit significant chloroquine-potentiating action against the FcB1 strain formerly described as a resistant strain but one which has since lost its resistance for unknown reasons. One other relevant result that arose from our study was the observation of the selective enhancing action of MG on quinolines (chloroquine, quinine, and mefloquine), aminoacridines (quinacrine and pyronaridine), and a structurally unrelated drug (halofantrine), all of which are believed to exert their antimalarial effect by binding with haematin. MG was finally found to specifically act with chloroquine on the old trophozoite stage of the P. falciparum cycle. Similarities and differences between verapamil and MG reversal activity are briefly presented.

Antiviral activities in plants endemic to madagascar.

In order to determine the potential of Malagasy plants as sources of antiviral activities, ethanolic extracts of 11 plants, endemic to Madagascar, were evaluated for antiviral activities. Nine of the extracts had significant activity against herpes simplex virus (HSV), whereas only four were active against Sindbis virus. Five extracts: Cynometra cloiselii , Cynometra madagascariensis , Evonymopsis longipes , Ravensara retusa , and Terminalia monoceros were particularly potent and could completely inactivate the HSV test inoculum (100 infectious virus particles) at concentrations of less than 25 µg/ml. Most of the active phytochemicals were photosensitizers. However, the combined properties of the active extracts indicated the presence of distinct compounds in different species. On the basis of these results we believe that it would be worthwhile expanding these studies to include additional species of Malagasy plants.

Effects of the naturally-occurring chemosensitizer malagashanine and its combination with chloroquine on KB and P388 cell lines and isolated auricle.

Besides the determination of its LD50 value, the cytotoxicity against KB and P388 cell lines and the toxicity on isolated guinea pig auricle of malagashanine and its combination with chloroquine were assessed. Malagashanine alone was devoid of cytotoxicity and cardiac effect on isolated auricle, and importantly, when combined to chloroquine, did not affect the inherent toxicity and cardiac toxicity of this antimalarial agent.

Alkaloids of Hernandia voyronii: chloroquine-potentiating activity and structure elucidation of herveline D.

Further investigation of Hernandia voyronii led to the isolation of a new pavine-benzyltetrahydroisoquinoline (pavine-BTIQ) dimer, herveline D, together with herveline A, five aporphine alkaloids, two morphinane alkaloids, and their bio-synthetic precursor, i.e., the BTIQ ( S)-reticuline. Hervelines A-D have a moderate intrinsic in vitro antimalarial activity (IC (50) in the range of 1.68-3.28 microM), but displayed different effects ranging from synergism for herveline B and herveline C to simple additive effect for herveline A, and antagonism for herveline D in a chloroquine (CQ) combination evaluation and this was confirmed in vivo for hervelines A and B. Furthermore, the antiplasmoidal activity of CQ was potentiated in vitro by reticuline and its dimethyl derivative laudanosine (for the latter also in vivo), whereas herveline C moderately potentiated in vitro the anti-plasmodial activity of herveline D.

Shark poisoning in Madagascar: a case report.

About 600 persons were injured in the shark poisoning which occurred in Vohipeno. east coastal region of Madagascar. Four deaths were recorded. Clinical symptoms of 310 cases admitted in the hospital suggested a ciguatera poisoning.

Shark Poisoning in Madagascar : a Case Report

About 600 persons were injured in the shark poisoning which occurred in Vohipeno. east coastal region of Madagascar. Four deaths were recorded. Clinical symptoms of 310 cases admitted in the hospital suggested a ciguatera poisoning

[Recent results on the pharmacodynamics of Strychnos malgaches alkaloids]. / Résultats récents sur la pharmacodynamie d'alcaloïdes de Strychnos malgaches.

Investigation of Strychnos (Loganiaceae) shrubs and trees was initiated by their traditional uses of their inherent poisons on arrows: this led to the discovery of strychnine and curare alkaloids. Subsequently, phytochemical investigation of several Strychnos species has shown great structural diversity of the alkaloid constituent which also display various biological effects, i.e. convulsive and relaxant effects on muscles, and antimicrobial, antitumor and antihypertensive properties. Ethnobotanical field work conducted in different regions of Madagascar revealed that infusion of three Strychnos species, S. mostueoides, S. myrtoides and S. diplotricha, is used in association with subcurative doses of chloroquine to treat chronic malaria. Bioassayfractionation led to the isolation of two major bioactive components, strychnobrasiline and malagashanine. Whereas strychnobrasiline is a previously known chemical compound, malagashanine is the first in a series of a new subtype of Strychnos alkaloids. These two alkaloids are devoid of intrinsic antimalarial effects, both in vitro (IC50 = 73.0 micrograms/ml for strychnobrasiline and 69.1 micrograms/ml for malagashanine) and in vivo (10 mg/kg conferred a 5% suppression of parasitemia). When these alkaloids are combined with chloroquine at doses much lower than required for antiplasmodial effects, they greatly enhance the chloroquine action in a dose dependent manner as seen by the isobologram method. Several minor alkaloids structurally related to malagashanine were also isolated from Madagascan Strychnos. They all enhance, to greater or lesser degrees, the chloroquine effectiveness. Interestingly, there is a positive correlation between the ethnomedical use of the three Strychnos species as chloroquine adjuvants and the chloroquine-potentiating effects of malagashanine and strychnobrasiline isolated from them. After preliminary toxicological studies, infusion of stem barks of S. myrtoides in association with chloroquine was successfully evaluated in a clinical setting. Additional chemical, pharmacological and toxicological work is being conducted on these alkaloids with the aim of developing purified and standardized extracts for clinical trials. These trials will be carried out in the chloroquine-resistant regions of Madagascar which are in need of inexpensive and efficient drugs for the treatment of chloroquine-resistant malaria.

Bisbenzylisoquinolines as modulators of chloroquine resistance in Plasmodium falciparum and multidrug resistance in tumor cells.

Ten naturally occurring bisbenzylisoquinolines (BBIQ) and two dihydro derivatives belonging to five BBIQ subgroups were evaluated in vitro for their ability to inhibit Plasmodium falciparum growth and, in drug combination, to reverse the resistance to chloroquine of strain FcB1. The same alkaloids were also assessed in vitro for their potentiating activity against vinblastine with the multidrug-resistant clone CCRF-CEM/VLB, established from lymphoblastic acute leukemia. Three of the BBIQ tested had 50% inhibitory concentrations of less than 1 microM. The most potent antimalarial agent was cocsoline (50% inhibitory concentration, 0.22 microM). Regarding the chloroquine-potentiating effect, fangchinoline exhibited the highest biological activity whereas the remaining compounds displayed either antagonistic or slight synergistic effects. Against the multidrug-resistant cancer cell line, fangchinoline was also by far the most active compound. Although there were clear differences between the activities of tested alkaloids, no relevant structure-activity relationship could be established. Nevertheless, fangchinoline appears to be a new biochemical tool able to help in the comprehension of the mechanism of both chloroquine resistance in P. falciparum and multidrug resistance in tumor cells.

Contribution a l'inventaire des plantes utilisees comme remedes et charmes dans la region sud de Madagascar

Dans le cadre des enquetes ethnobotaniques sur le terrain; les auteurs ont recense 81 plantes ayant des proprietes medicinales et/ou sont utlisees comme charme; dans la region sud de Madagascar. Leurs noms scientifiques; vernaculaires et utilisations traditionnelles sont donnes