Anti-Pneumocystis carinii pneumonia activity of dicationic 2,4-diarylpyrimidines

— A synthesis of 2,4-bis-(4-amidinophenyl)pyrimidine 6, 2,4-bis-[(4-imidazolin-2-yl)phenyl)]pyrimidine 7, 2,4-bis[(4-tetrahydropyrimidinyl-2-yl)phenyl]pyrimidine 8, 2,4-bis[(4-N-n-propylamidino)phenyl]pyrimidine 9, 2,4-bis[(4-N-isopropylamidino)-phenyl]pyrimidine 10 and 2,4-bis[(4-N-isobutylamidino)phenyl]pyrimidine 11 starting from 4-bromobenzamidine and 4-bromoaceto-phenone is reported. A synthesis of 2-(4-amidinophenyl)-4-(2-methoxy-4-amidinophenyl)pyrimidine 20, 2-[4-(imidazolin2-yl)-phenyl]-4-[2-methoxy-4-(imidazolin-2-yl)phenyl]pyrimidine 21, and 2-[4-(N-iso-propylamidino)phenyl]-4-[2-methoxy-4-(N-isopropylamidino)phenyl]pyrimidine 22 beginning with 4-bromobenzamidine and 2-methoxy-4-bromoacetophenone is described. Compounds 6–11 and 20–22 all bind strongly to DNA. Compounds 6, 9–11, and 20 given at 5 mg/kg are more active and less toxic than pentamidine at its effective dose when evaluated against Pneumocystis carinii pneumonia (PCP) in the immunosuppressed rat model. Several compounds in this series are being evaluated further as potential new anti-PCP agents

Synthesis of dicationic diaryltriazines nucleic acid binding agents

— The synthesis of 2,4-bis[4-(4,5-dihydro-1H-imidazol-2-yl)phenyl]-1,3,5-triazine 6a and 2,4-bis[4-(1,4,5,6-tetrahydropyrimidin-2-yl)phenyl]-1,3,5-triazine 6b in 3 steps from either 4-bromobenzamidine or 4-(carbamoyl)benzamidine is reported. The synthesis of 4,6-bis[4-(4,5-dihydro-1H-imidazol-2-yl)phenyl]-2-dimethylamino-1,3,5-triazine 9a and 4,6-bis[4-(1,4,5,6-tetrahydropyrimidin-2-yl)phenyl]-2-dimethylamino-1,3,5-triazine 9b in 2 steps from 1,4-dicyanobenzene is also described. The compounds 6b and 9b bind strongly to DNA model sequences and inhibit topoisomerase II from 2 microbial sources. Compounds 6a and 9a bind to both DNA and RNA model sequences whereas 6b and 9b essentially do not bind to the RNA model

Synthesis of dicationic diarylpyridines as nucleic-acid binding agents

The syntheses of 2,6-bis[4-(4,5-dihydro-1H-imidazol-2-yl)phenyl]pyridine 7, 2-[4-(4,5-dihydro-1H-imidazol-2-yl)-phenyl]-6-[3-(4,5-dihydro-1H-imidazol-2-yl)phenyl]pyridine 8 and 2,6-bis[3-(4,5-dihydro-1H-imidazol-2-yl)phenyl]pyridine 9 in five steps from the appropriately substituted bromoacetophenone are described. 3,5-Bis[4-(4,5-dihydro-1H-imidazol-2-yl)phenyl]pyridine 13 is also reported, prepared in four steps from 4-bromophenylacetonitrile. The preparation of 2,5-bis[4-(4,5-dihydro-1H-imidazol-2-yl)-phenyl]pyridine 18 from 4-bromoacetophenone in six steps is presented. The dications bind to poly dA·dT in the order 7 > 13 > 18 > 8 > 9; the order of binding to poly A·U is 7 > 13 > 8 > 9; 18 essentially does not bind to the RNA model. Only 7 inhibits topoisomerase II at millimolar concentrations. The dicationic compounds that were tested against Pneumonocystis carinii in the immuno-suppressed rat model show only modest activity and are moderately toxic. Some of the compounds demonstrated modest anti-HIV-1 activity and selectivity in primary lymphocytes

Positively selected modifications in the pore of TbAQP2 allow pentamidine to enter Trypanosoma brucei

Mutations in the Trypanosoma brucei aquaporin AQP2 are associated with resistance to pentamidine and melarsoprol. We show that TbAQP2 but not TbAQP3 was positively selected for increased pore size from a common ancestor aquaporin. We demonstrate that TbAQP2’s unique architecture permits pentamidine permeation through its central pore and show how specific mutations in highly conserved motifs affect drug permeation. Introduction of key TbAQP2 amino acids into TbAQP3 renders the latter permeable to pentamidine. Molecular dynamics demonstrates that permeation by dicationic pentamidine is energetically favourable in TbAQP2, driven by the membrane potential, although aquaporins are normally strictly impermeable for ionic species. We also identify the structural determinants that make pentamidine a permeant although most other diamidine drugs are excluded. Our results have wide-ranging implications for optimising antitrypanosomal drugs and averting cross-resistance. Moreover, these new insights in aquaporin permeation may allow the pharmacological exploitation of other members of this ubiquitous gene family

The biological in vitro effect and selectivity of aromatic dicationic compounds on Trypanosoma cruzi

Trypanosoma cruzi is a parasite that causes Chagas disease, which affects millions of individuals in endemic areas of Latin America. One hundred years after the discovery of Chagas disease, it is still considered a neglected illness because the available drugs are unsatisfactory. Aromatic compounds represent an important class of DNA minor groove-binding ligands that exhibit potent antimicrobial activity. This study focused on the in vitro activity of 10 aromatic dicationic compounds against bloodstream trypomastigotes and intracellular forms of T. cruzi. Our data demonstrated that these compounds display trypanocidal effects against both forms of the parasite and that seven out of the 10 compounds presented higher anti-parasitic activity against intracellular parasites compared with the bloodstream forms. Additional assays to determine the potential toxicity to mammalian cells showed that the majority of the dicationic compounds did not considerably decrease cellular viability. Fluorescent microscopy analysis demonstrated that although all compounds were localised to a greater extent within the kinetoplast than the nucleus, no correlation could be found between compound activity and kDNA accumulation. The present results stimulate further investigations of this class of compounds for the rational design of new chemotherapeutic agents for Chagas disease

EFFECTS OF CLEAR AND TINTED FOOTBALL VISORS ON AGILITY AND FUNCTIONAL REACTIVE ABILITY IN NCAA FOOTBALL PLAYERS

Gracie Robbins, Shelby Tidwell, Rebecca R. Rogers, Nathan East, Amanda Dumar, Ashleigh Davis, Ashley Rice, Christopher G. Ballmann, FACSM. Samford University, Birmingham, AL. BACKGROUND: Football helmet visors have been added as safety accessories to helmet facemasks in efforts to mitigate ocular injury. Recent rule changes have banned tinted visors while clear visors are generally accepted as legal. We have previously shown that dark tinted helmet visors impair peripheral visuomotor ability in collegiate players. However, athletes were stationary when completing reaction time tests which may not translate to actual gameplay. PURPOSE: The purpose of this study was to identify how clear and tinted visors influence agility and functional reactive ability in NCAA football players. METHODS: Division 1 NCAA football players with normal/corrected to normal vision participated. In a randomized manner, participants completed reactive tests for the following conditions: Baseline/no helmet (BL), Helmet + Clear visor (HCV), Helmet + Smoke tinted visor (HSV), Helmet + Mirrored visor (HMV). For each condition, participants completed two reactive tests using a FITLIGHT trainer system: reactive reach test (RRT) and reactive step test (RST). For the RRT, 5 poles equipped with a total of 10 LED sensors were placed in a semi-circle 1 meter around a center point. Participants were asked to step and reach to hit 10 lights with their hands as fast as possible. For the RST, 5 LED sensors were place on the ground in a semi-circle pattern 1 meter around a center point. Participants were asked to step and hit each sensor with their foot to hit 5 lights as fast as possible. Each reactive test was repeated for a total of 3 attempts. Average reaction time and time to test completion (TTC) were analyzed and compared between visor conditions. RESULTS:HCV (p\u3c 0.001), HSV (p\u3c 0.001), and HMV (p\u3c0.001) conditions resulted in slower reaction time during RRT compared to BL. TTC was significantly increased during the HCV (p\u3c 0.001), HSV (p\u3c 0.001), and HMV (p\u3c0.001) conditions versus BL. However, no differences existed between visor conditions (p\u3e 0.05). For the RST, reaction time was slower during HCV (p= 0.028), HSV (p= 0.038), and HMV (p= 0.017) conditions versus BL. TTC was significantly higher during the HCV (p= 0.010), HSV (p= 0.009), and HMV (p=0.007) versus BL. No differences existed between facemask conditions (p\u3e 0.05). CONCLUSIONS: Regardless of visor condition, wearing a football helmet impaired functional reactive ability and agility performance. However, visor tint did not exacerbate functional reactive ability. These findings highlight the need for new helmet designs which may not obstruct lines of sight to maintain player safety and performance in collegiate football players

Detection of arsenical drug resistance in Trypanosoma brucei with a simple fluorescence test

The resurgence of human African trypanosomiasis (HAT), coupled with an increased incidence of drug resistance, is of concern. We report a quick, simple, and sensitive test for identification of parasites resistant to melarsoprol, the main drug used to treat late stage HAT. Resistant parasites are defective in a plasma membrane transporter responsible for drug uptake. The same transporter carries the fluorescent diamidine DB99 (2,5-bis-(4-amidinophenyl)-3,4-dimethylfuran) into trypanosomes. The two DNA-containing structures in the trypanosome—the nucleus and the kinetoplast—begin to fluoresce within 1 min of introduction of DB99, unless drug resistant