Michel Sauvain

A search for natural bioactive compounds in Bolivia through a multidisciplinary approach. Part V. Evaluation of the antimalarial activity of plants used by the Tacana Indians.

Thirty extracts of plants traditionally used by the Chacobos, a native community living in the Amazonian part of Bolivia, were screened in vitro and/or in vivo for antimalarial activity. Two of the four species designated as antimalarial, Geissospermum laeve and Maquira coriacea, displayed rather good activity, corroborating their traditional uses. However, they did show a rather high toxicity in vivo. Among twelve species used to cure symptoms relevant to malaria, five showed good activity: Apuleia leiocarpa, Bauhinia guianensis, Nectandra cuspidata, Sparattanthelium amazonum, Tanaecium jaroba. Two species, Qualea paraensis and Sclerolobium aff. guianense, used to treat scabies, showed interesting antimalarial activity in vivo; three other species (Iryanthera laevis, Prunus amplifolia, Pterocarpus aff. amazonum) used for various medicinal purposes, apparently not related with a Plasmodium infection, also showed antimalarial activity. Finally, one species (Derris amazonica) used as a piscicide displayed good in vitro activity, in the same way as one Annonaceae, Guatteria aff. schomburgkiana, used for construction purposes.

A search for natural bioactive compounds in Bolivia through a multidisciplinary approach: Part IV. Is a new haem polymerisation inhibition test pertinent for the detection of antimalarial natural products?

The search for new antimalarial agents in plant crude extracts using traditional screening tests is time-consuming and expensive. New in vitro alternative techniques, based on specific metabolic or enzymatic process, have recently been developed to circumvent testing of antimalarial activity in parasite culture. The haem polymerisation inhibition test (HPIA) was proposed as a possible routine in vitro assay for the detection of antimalarial activity in natural products. A total of 178 plant extracts from the Pharmacopeia of the Bolivian ethnia Tacana, were screened for their ability to inhibit the polymerisation of haematin. Five extracts from Aloysia virgata (Ruíz & Pavón) A.L. Jussieu (Verbenaceae), Bixa orellana L. (Bixaceae), Caesalpinia pluviosa D.C. (Caesalpiniaceae), Mascagnia stannea (Griseb) Nied. (Malpighiaceae) and Trichilia pleenea (Adr. Jussieu) (Meliaceae) demonstrated more than 70% inhibition of haematin polymerisation at 2.5 mg/ml. The extracts were also tested for antimalarial activity in culture against F32 strain (chloroquine-sensitive) and D2 strain (chloroquine-resistant) of Plasmodium falciparum and in vivo against P. berghei. The extract from Caesalpinia pluviosa was the only one that showed activity in HPIA and in the classical test in culture. The accuracy and pertinence of HPIA, applied to natural products is discussed.

The search for natural bioactive compounds through a multidisciplinary approach in Bolivia. Part II. Antimalarial activity of some plants used by Mosetene indians.

Forty-six different species collected in the Mosetene ethnia, dwelling in the Andean Piedmont of Bolivia, were screened for antimalarial properties. Thirty-three extracts were screened for antimalarial activity in vitro on Plasmodium falciparum chloroquine resistant strain (Indo), and forty-seven extracts were evaluated in vivo on the rodent malaria P. vinckei petteri 279BY. Only two plants are specifically used in combination by the Mosetene against malaria attack (Hymenachne donacifolia and Tesseria integrifolia), but they did not display any activity in vivo at 1000 mg/kg. The in vivo most active extracts were Swietenia macrophylla bark, Trema micrantha bark and Triplaris americana bark, not all of them were used for antimalarial purposes by the Mosetene. The following extracts were moderately active: Jacaratia digitata inner bark and Momordica charantia aerial part (both traditionally used as febrifuge), Kalanchoe pinnate aerial part (used in inflammatory processes), Lunania parviflora twigs and leaves, Phyllanthus acuminatus (used as piscicide), Tynanthus schumannianus fruit (used against diarrhoea), Triumfetta semitrilobata (used as febrifuge, to alleviate kidney and gynecological pain) and finally Solanum mammosum fruit (used against scabies). We present here the results of this screening, emphazing on the in vivo antimalarial activity of the selected plants. The antimalarial in vivo activity of the selected species, in relation with their traditional Mosetene use is then discussed.

In vitro and in vivo activity of benzo[c]phenanthridines against Leishmania amazonensis.

Seven benzo[c]phenanthridines, synthetic or isolated from Zanthoxylum rhoifolium root bark, were evaluated against Leishmania amazonensis axenic amastigotes. Five of them were considered leishmanicidal, with IC50 values ranging from 0.03 to 0.54 µM, and were evaluated on intramacrophagic amastigotes of L. amazonensis. Chelerythrine displayed the best activity (IC50=0.5 µM), which was in the same range as the reference compound amphotericin B (IC50=0.4 µM). In vivo studies with chelerythrine, avicine, and fagaridine on a model of mice cutaneous leishmaniasis resulted in the identification of fagaridine as the most active compound. Fagaridine decreased the parasitic burden more than 50% at the 3rd and 6th weeks after the end of treatment.

Anti-infective assessment of Senecio smithioides (Asteraceae) and isolation of 9-oxoeuryopsin, a furanoeremophilane-type sesquiterpene with antiplasmodial activity

Abstract The search for anti-infective activity in the antipyretic plant Senecio smithioides was conducted. Petroleum ether (PE), dichloromethane (CH2Cl2), ethyl acetate (EtOAc) and hydroethanolic (96% EtOH) extracts, and compounds 9-oxoeuryopsin (1), epoxydecompostin (2) and senecionine (3) were obtained from the aerial parts. All extracts and 1 were tested against chloroquine-resistant strain of Plasmodium falciparum (ref. chloroquine), Trypanosoma cruzi (ref. nifurtimox), Leishmania braziliensis, Leishmania amazonensis and Leishmania donovani (ref. pentamidine), Staphylococcus aureus and Escherichia coli (ref. gentamicin) and, Neurospora crassa and Candida albicans (ref. ketoconazole). The PE extract exhibited the strongest in vitro activity against Plasmodium falciparum IC50 < 1.0 μg/mL. 1 was established as a potent antiplasmodial compound with an IC50 = 1.2 μg/mL, 5.2 μM. Other antiparasitic activities were recorded for all extracts and 1. Antibacterial and antifungal activity was negligible.

A new 5-alkylresorcinol glucoside derivative from Cybianthus magnus

One new 5-alkylresorcinol glucoside (1) was isolated from leaves of Cybianthus magnus, along with 12 known compounds, isolated from four plants belonging to Myrsinaceae family (2, 3 isolated from C. magnus; 4–7, 10 and 11 isolated from Myrsine latifolia; 4, 8 and 9 isolated from Myrsine sessiflora; 6, 7, 10, 12 and 13 isolated from Myrsine congesta). Their structures were determined on the basis of spectroscopic analysis and by comparison of their spectral data with those reported in the literature. So far, only nine 5-alkylresorcinol glucosides were isolated from leaves of Grevillea robusta. Since resorcinols are known to exhibit strong cytotoxic activity, compounds 1 and 2 were tested against cell lines 3T3, H460, DU145 and MCF-7 for cytotoxicity in vitro and compounds 3–13 were tested for their antileishmanial activity. Compound 2 displayed a strong cytotoxic activity with IC50 values ranging between 22 and 100 μM for all tested cell lines. Compounds 3–13 were not active against Leishmania amazonensis amastigotes. One new 5-alkylresorcinol glucoside (1) was isolated from leaves of Cybianthus magnus, along with 12 known compounds (2–13), isolated from four plants belonging to Myrsinaceae family. Their structures were determined on the basis of spectroscopic analysis and by comparison of their spectral data with those reported in the literature. Among the tested molecules, only compound 2 displayed a strong cytotoxic activity with IC50 values ranging between 22 and 100 μM for all cell lines tested.

Phytochemical study of four plants from the family Myrsinaceae

Four Peruvian plants (Cybianthus magnus, Myrsine latifolia, Myrsine congesta and Myrsine sessiliflora) belonging to the Myrsinaceae family have been studied in search of molecules with antileishmanial activity. From the hydromethanolic extract of three parts of each plant (leaves, stem and roots) 10 compounds were purified and identified. The purification was performed using chromatographic methods (HPLC; semi preparative chromatography) and the structure elucidation was accomplished by 1D, 2D NMR spectra (1H-1H, 13C, DEPT, COSY, HSQC, HMBC). One new compound was isolated and identified as 5-alkylresorcinolglucoside, named Cybianthoside A (1), from C. magnus. From the other plants, six flavonoids were isolated: (-) catechin, catechin-3-O-rhamnopyranoside (2), quercetin-3-O-rhamnopyranoside (3), isorhamnetin-3-O-rhamnopyranoside (4), quercetin-3-O-arabinopyranoside (5) and quercetin-3-O-arabinofuranoside (6); one lignan: lyoniresinol-9-O-glucopyranoside (7); one resorcinol derivative: 12Z-5-heptadec-12-enylresorcinol (8) and two chromanes: myrsinoic acid B (9) and myrsinoic B methyl ester (10). Extracts and fractions were evaluated for their antileishmanial activity but no activity was detected. Acknowledgements: The authors are grateful to the FRB (Fondation pour la Recherche sur la Biodiversite, France) for the financial support through a grant to Dr. M. Haddad (Project DIPERSAP). The authors thank Rodolfo Vasquez, Rocio Rojas, Jose Mateo and Juan Perea from the Missouri Botanical Garden of Oxapampa, Peru and Carlos Amasifuen, for their help to collect the plants for this project. The authors thank MESR for a grant and the AFERP for financing participation in GA2014 Congress.