Recent Advances in the Development of Broad-Spectrum Antiprotozoal Agents.

Infections caused by Trypanosoma brucei, Trypanosoma cruzi, Leishmania spp., Entamoeba histolytica, Giardia lamblia, Plasmodium spp., and Trichomonas vaginalis, are part of a large list of human parasitic diseases. Together, they cause more than 500 million infections per year. These protozoa parasites affect both low- and high-income countries and their pharmacological treatments are limited. Therefore, new and more effective drugs in preclinical development could improve overall therapy for parasitic infections even when their mechanisms of action are unknown. In this review, a number of heterocyclic compounds (diamidine, guanidine, quinoline, benzimidazole, thiazole, diazanaphthalene, and their derivatives) reported as antiprotozoal agents are discussed as options for developing new pharmacological treatments for parasitic diseases.

Old Antiprotozoal Drugs: Are They Still Viable Options for Parasitic Infections or New Options for Other Diseases?

Parasitic diseases, caused by helminths (ascariasis, hookworm, trichinosis, and schistosomiasis) and protozoa (chagas, leishmaniasis, and amebiasis), are considered a serious public health problem in developing countries. Additionally, there is a limited arsenal of anti-parasitic drugs in the current pipeline and growing drug resistance. Therefore, there is a clear need for the discovery and development of new compounds that can compete and replace these drugs that have been controlling parasitic infections over the last decades. However, this approach is highly resource- intensive, expensive and time-consuming. Accordingly, a drug repositioning strategy of the existing drugs or drug-like molecules with known pharmacokinetics and safety profiles is alternatively being used as a fast approach towards the identification of new treatments. The artemisinins, mefloquine, tribendimidine, oxantel pamoate and doxycycline for the treatment of helminths, and posaconazole and hydroxymethylnitrofurazone for the treatment of protozoa are promising candidates. Therefore, traditional antiprotozoal drugs, which were developed in some cases decades ago, are a valid solution. Herein, we review the current status of traditional anti-helminthic and antiprotozoal drugs in terms of drug targets, mode of action, doses, adverse effects, and parasite resistance to define their suitability for repurposing strategies. Current antiparasitic drugs are not only still viable for the treatment of helminth and protozoan infections but are also important candidates for new pharmacological treatments.

Anticancer Activity of Resorcinarene-PAMAM-Dendrimer Conjugates of Flutamide.

METHODS: The synthesis of conjugates of flutamide with resorcinarene-PAMAM-dendrimers as well as alkyl and ethyl phenyl chains in the lower part of the macrocycle as a nucleus and diethylenetriamines in the dendritic branches gives the opportunity to obtain conjugates in one step of synthesis with 16 and 64 flutamide moieties in the structure. RESULTS: The in vitro anticancer studies showed that the conjugates of flutamide are more active than the free flutamide and the flutamide derivatives, thus diminishing the amount of flutamide used. The resorcinarenedendrimer- flutamide conjugates with a high drug payload improve the activity of the drug. CONCLUSION: This is important in delivering a sufficient amount of flutamide and suggests that the dendrimer facilitates more of the drug being introduced into cells. It was also observed that the new conjugates are less toxic than the anti-androgens.

Synthesis, Characterization, and Nanomedical Applications of Conjugates between Resorcinarene-Dendrimers and Ibuprofen.

Ibuprofen has been reported to possess anticancer activity. In the present work, four ibuprofen conjugates of resorcinarene-Polyamidoamine PAMAM-dendrimers were synthesized with eight or 16 ibuprofen moieties. The ibuprofen was released from the dendrimers in a dependent manner. The drug-conjugated nanoresorcinarene-dendrimers showed higher cellular uptake than free ibuprofen. In vitro cytotoxicity studies were performed with free ibuprofen and with the synthesized conjugates in U251, PC-3, K-562, HCT-15, MCF-7, SKLU-1, and MDA U251 (human glioblastoma), PC-3 (human prostatic adenocarcinoma), K-562 (human chronic myelogenous leukemia cells), HCT-15 (human colorectal adenocarcinoma), MCF-7 (human mammary adenocarcinoma), SKLU-1 (human lung adenocarcinoma), and MDA-MB-231 (human mammary adenocarcinoma) cancer cell lines by different cytotoxicity assays. Ibuprofen conjugates of the first and second generations showed significant cytotoxic effects towards the human glioblastoma (U251) and human mammary adenocarcinoma (MCF-7, MDA) cell lines. Moreover, the ibuprofen conjugates improved cytotoxicity compared to free ibuprofen. Increased therapeutic efficacy was observed with specific ibuprofen conjugates of the second generation using low doses.

High Fluorescent Porphyrin-PAMAM-Fluorene Dendrimers.

Two new classes of dendrimers bearing 8 and 32 fluorene donor groups have been synthesized. The first and second generations of these porphyrin-PAMAM-fluorene dendrimers were characterized by 1H-NMR, 13C-NMR, FTIR, UV-vis spectroscopy, elemental analyses and MALDI-TOF mass spectrometry. The UV-vis spectra showed that the individual properties of donor and acceptor moieties were preserved, indicating that the new dendrimers could be used as photosynthetic antennae. Furthermore, for fluorescent spectroscopy, these dendrimers showed good energy transfer.

Synthesis of 5-aryl-1,4-benzodiazepine derivatives attached in resorcinaren-PAMAM dendrimers and their anti-cancer activity.

A series of resorcinaren-PAMAM dendrimers with benzodiazepines in the periphery were synthesized and their anticancer properties studied. The synthesized dendrimers showed potential anticancer activities, which were enhanced in the presence of a chloro-substituent in the second ring of the 5-aryl-1,4-benzodiazepine. The dendrimers were characterized by IR, (1)H and (13)C NMR, UV-vis absorption, electrospray (ES) and/or MALDI-TOF mass spectrometries.