Rosa Moo-Puc

Design, synthesis and in vitro antiprotozoal activity of benzimidazole-pentamidine hybrids

A series of ten novel hybrids from benzimidazole and pentamidine were prepared using a short synthetic route. Each compound was tested in vitro against the protozoa Trichomonas vaginalis, Giardia lamblia, Entamoeba histolytica, Leishmania mexicana, and Plasmodium berghei, in comparison with pentamidine and metronidazole. Some analogues showed high bioactivity in the low micromolar range (IC(50)<1 microM) against the first four protozoa, which make them significantly more potent than either standard. 1,5-bis[4-(5-methoxy-1H-benzimidazole-2-yl)phenoxy]pentane (2) was 3- and 9-fold more potent againstG. lamblia than metronidazole and pentamidine, respectively. This compound was 23-, 108-, and 13-fold more active than pentamidine against T. vaginalis, E. histolytica and L. mexicana, respectively. Studying further structure-activity relationships through the use of bioisosteric substitution in these hybrids should provide new leads against protozoal diseases.

Evaluation of selected tropical seaweeds for in vitro anti-trichomonal activity

ETHNOPHARMACOLOGICAL RELEVANCE Human parasitic infections are a serious problem in tropical and sub-tropical developing countries. Trichomoniasis, responsible for the annual infection of 180 million people, is a common sexually transmitted disease caused by the protozoan Trichomonas vaginalis. Traditionally seaweeds have been used in folk medicine by coastal people in Asia and the Caribbean to treat parasitic infections and are a valuable source of novel anti-trichomonals. AIM OF THE STUDY In our search for therapeutical alternatives to anti-protozoal chemotherapy, we collected a selection of 25 tropical seaweeds (12 Rhodophyta, 5 Phaeophyta and 8 Chlorophyta) from the coast of Yucatan (Mexico) in order to undertake ethnopharmacological and chemotaxonomic investigations. MATERIALS AND METHODS Organic algal extracts were tested for their anti-trichomonal properties on the growth inhibition of Trichomonas vaginalis. The cytotoxicity of seaweed extracts on mammal cell lines was also assessed. RESULTS The results indicated that 44% of the seaweeds studied had high to moderate anti-trichomonal activity. Lobophora variegata and Udotea conglutinata showed the maximal anti-trichomonal activity with IC(50) values of 1.39 and 1.66microg/ml, respectively, with good selectivity. CONCLUSIONS Lobophora variegata and Udotea conglutinata demonstrated promising anti-trichomonal potential and have been selected for further bio-guided fractionation and isolation of active anti-trichomonal compounds.

In vitro activity of Tridax procumbens against promastigotes of Leishmania mexicana.

ETHNOPHARMACOLOGICAL RELEVANCE Tridax procumbens is an active herb against leishmaniasis. AIM OF THE STUDY Leishmaniasis is a group of diseases caused by Leishmania protozoa. We investigated the antileishmanial activity of Tridax procumbens extracts and a pure compound against promastigotes of Leishmania mexicana, the causative agent of cutaneous leishmaniasis in the New World. MATERIALS AND METHODS Extracts and (3S)-16,17-didehydrofalcarinol (1) were obtained by chromatographic methods from Tridax procumbens, and the latter identified by spectroscopic analysis. The effect of these extracts and 1 on the growth inhibition of promastigotes of Leishmania mexicana was evaluated. In order to test the safety of extracts and 1, mammalian cells were treated with them, and cell viability was assessed using trypan blue and MTT. RESULTS We demonstrated that extracts of Tridax procumbens and 1 showed a pronounced activity against Leishmania mexicana. The methanol extract inhibited promastigotes growth of Leishmania mexicana with a 50% inhibitory concentration (IC(50)) of 3 microg/ml, while oxylipin 1 exhibited the highest inhibition at IC(50)=0.478 microg/ml. CONCLUSIONS In this study we report the biological activity of extracts and (3S)-16,17-didehydrofalcarinol (1), obtained from Tridax procumbens, on the promastigote form of Leishmania mexicana, with no effect upon mammalian cells.

Synthesis and in vitro trichomonicidal, giardicidal and amebicidal activity of N-acetamide(sulfonamide)-2-methyl-4-nitro-1H-imidazoles

Two new series of imidazole derivatives (acetamides: 1-8 and sulfonamides: 9-15) were synthesized using a short synthetic route. Compound 1 as well as the intermediate 16g were characterized by X-ray crystallography. Imidazole derivatives 1-15 were tested in vitro against three unicellular parasites (Giardia intestinalis, Trichomonas vaginalis and Entamoeba histolytica) in comparison with benznidazole (Bzn) and metronidazole. Compound 1 [N-benzyl-2-(2-methyl-4-nitro-1H-imidazol-1-yl)acetamide] was 2 times more active than Bzn against T. vaginalis and G. intestinalis and it was as active as Bzn against E. histolytica. Sulfonamides showed selective toxicity against E. histolytica over the other parasites. Toxicity assay showed that all compounds are non-cytotoxic against MDCK cell line. The results revealed that compounds 1-15 have antiparasitic bioactivity in the micromolar range against the parasites tested, and could be considered as benznidazole bioisosteres.

In vitro cytotoxic activity of nine plants used in Mayan traditional medicine.

ETHNOPHARMACOLOGICAL RELEVANCE Plants have been used in folk medicine by Mayan ancient people from the Yucatan Peninsula, Mexico, to treat some diseases considered as cancer diseases such as chronic wounds or tumors. AIM OF THE STUDY We collected a selection of nine plants in order to investigate their cytotoxic activity against cancer cell lines. MATERIALS AND METHODS Methanolic extracts were tested for their cytotoxicity using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay on four cancer cell lines; nasopharynx carcinoma (KB), laryngeal carcinoma (Hep-2), cervix adenocarcinoma (HeLa), and cervix squamous carcinoma cells (SiHa) and one normal cell line; canine kidney (MDCK). RESULTS All species exhibited some degree of cytotoxic activity. The root bark extract of Hamelia patens exhibited the highest cytotoxic activity on HeLa cells with a CC50 of 13 microg/mL and selectivity index of 13.3, higher than docetaxel. Gossypium schottii and Dioon spinulosum showed similar good cytotoxic activity and selectivity index on HeLa and Hep-2 cells, respectively. CONCLUSIONS Hamelia patens, Dioon spinulosum and Gossypium schottii demonstrated promising cytotoxic activity and have been selected for future bio-guided fractionation and isolation of active cytotoxic compounds.

Screening of plants used in Mayan traditional medicine to treat cancer-like symptoms

AIM OF THE STUDY To investigate the potential of plants used in Mayan traditional medicine to treat cancer-like symptoms using the Mayan ethnobotany literature, and evaluate their organic extracts for in vitro cytotoxic activity on cancer cell lines. MATERIALS AND METHODS The selection of the plants studied in this investigation was based on the Mayan ethnobotanical information provided by different literature sources. Extracts were obtained by maceration with methanol for 72 h of each plant part used and evaporated in vacuo to give the corresponding dried extract. Each methanol extract was tested for its cytotoxicity using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay performed in 96-well tissue plates on seven cancer cell lines, lung carcinoma (A549), cervix adenocarcinoma (HeLa), laryngeal carcinoma (Hep-2), nasopharynx carcinoma (KB), breast adenocarcinoma (MCF-7), prostate adenocarcinoma (PC-3), and cervix squamous carcinoma cells (SiHa), as well as normal human embryonic kidney cell line (HEK-293). Cell proliferation/viability was spectrophotometrically assessed at 540 nm after addition of MTT. RESULTS 51 plants were found in the literature to be used for the treatment of symptoms suggestive of cancer, 21 were chosen to evaluate the cytotoxic activity. Aeschynomene fascicularis root bark extract showed a pronounced cytotoxic activity on Hela and KB cell lines and Bonellia macrocarpa stem and root bark extracts showed similar prominent activities on KB cells. CONCLUSION 21 plants were selected according to their use in the treatment of cancer-like symptoms recorded in the ethnobotanical literature. Plant extracts prepared from Aeschynomene fascicularis root bark and Bonellia macrocarpa stem and root bark have been selected for extensive studies leading to the isolation of the active constituents.

New 2-benzylsulfanyl-nicotinic acid based 1,3,4-oxadiazoles: Their synthesis and biological evaluation

A novel series of 5-(2-benzylsulfanyl-pyridin-3-yl)-2-(substituted)-sulfanyl-1,3,4-oxadiazoles 6a-j were synthesized from key intermediate 5-(2-benzylsulfanyl-pyridin-3-yl)-3H-[1,3,4]oxadiazole-2-thione 5. Nucleophilic substitution reactions with different electrophiles (E+), such as haloacetate and haloalkyl groups, were performed to get target compounds 6a-j. Compounds were characterized by NMR, mass, IR spectra and C, H, N analyses. All compounds were evaluated for their antimicrobial and antimycobacterial activities; selected analogs were screened for their anticancer activity on 60 tumor cell lines at single dose 1.00(-5) M. Unfortunately, none of the compounds showed a significant antitumor activity on 60 human tumor cell lines. However, compounds 6g and 6f with benzothiazole moiety (12.5 and 25 μg/ml) showed promising activity against Escherichia coli compared to ampicillin; compounds 6d, 6j bearing triazole and morpholine, respectively, showed promising antitubercular activity (25 μg/ml) compared to rifampicin.

Synthesis of benzologues of Nitazoxanide and Tizoxanide: A comparative study of their in vitro broad-spectrum antiprotozoal activity

We have synthesized two new benzologues of Nitazoxanide (NIT) and Tizoxanide (TIZ), using a short synthetic route. Both compounds were tested in vitro against six protozoa (Giardia intestinalis, Trichomonas vaginalis, Entamoeba histolytica, Plasmodium berghei, Leishmania mexicana and Trypanosoma cruzi). Compound 1 (benzologue of NIT) showed broad antiprotozoal effect against all parasites tested, showing IC(50)s<5 μM. This compound was five-times more active than NIT, and 18-times more potent than metronidazole against G. intestinalis. It was 10-times more active than pentamidine against L. mexicana, and it was sevenfold more potent than benznidazole versus T. cruzi. This compound could be considered as a new broad spectrum antiprotozoal agent.

2-acylamino-5-nitro-1,3-thiazoles: preparation and in vitro bioevaluation against four neglected protozoan parasites.

The 2-acylamino-5-nitro-1,3-thiazole derivatives (1-14) were prepared using a one step reaction. All compounds were tested in vitro against four neglected protozoan parasites (Giardia intestinalis, Trichomonas vaginalis, Leishmania amazonensis and Trypanosoma cruzi). Acetamide (9), valeroylamide (10), benzamide (12), methylcarbamate (13) and ethyloxamate (14) derivatives were the most active compounds against G. intestinalis and T. vaginalis, showing nanomolar inhibition. Compound 13 (IC50=10nM), was 536-times more active than metronidazole, and 121-fold more effective than nitazoxanide against G. intestinalis. Compound 14 was 29-times more active than metronidazole and 6.5-fold more potent than nitazoxanide against T. vaginalis. Ureic derivatives 2, 3 and 5 showed moderate activity against L. amazonensis. None of them were active against T. cruzi. Ligand efficiency indexes analysis revealed higher intrinsic quality of the most active 2-acylamino derivatives than nitazoxanide and metronidazole. In silico toxicity profile was also computed for the most active compounds. A very low in vitro mammalian cytotoxicity was obtained for 13 and 14, showing selectivity indexes (SI) of 246,300 and 141,500, respectively. Nitazoxanide showed an excellent leishmanicidal and trypanocidal effect, repurposing this drug as potential new antikinetoplastid parasite compound.

Antitrypanosomal in vitro activity of tropical marine algae extracts

Trypanosomiasis is one of the most important parasitic diseases worldwide. The undesirable side effects and low efficacy of classical trypanocidal drugs underline the necessity of the development of new drugs from natural products. Although marine algae have been recognized as attractive sources of known and novel bioactive compounds, very little research has been focused on antiprotozoal activity. Aqueous and organic extracts of 29 species of marine algae (14 species of Rhodophyta, seven species of Phaeophyta, and eight species of Chlorophyta) collected from the Gulf of Mexico and Caribbean coast of the Yucatan Peninsula (Mexico) were evaluated for their antiprotozoal activity in vitro against Trypanosoma cruzi trypomastigotes. The toxicity of these extracts was evaluated using brine shrimp (Artemia salina). The cytotoxicity on mammalian cells was also assessed by the MTT viability assay. The organic extracts from Dictyota caribea Horning & Schnetter, Lobophora variegata (J.V. Lamouroux) Womersley, Turbinaria turbinata Linnaeus, and Laurencia microcladia Kützing possess promising in vitro activity against T. cruzi trypomastigotes. The toxicity displayed by Laurencia microcladia against Artemia salina and the high cytotoxicity exhibited by T. turbinata must be taken into account in further studies.