Endohelminth diversity in the invasive Clarias gariepinus (Burchell, 1822) from two freshwater lakes: Naivasha and Ol'Bolossat, Kenya.

Fish parasitology contributes to our understanding of the potential risks posed by diverse groups of parasitic organisms on fish stocks in either wild and culture systems. This study was conducted in May 2023 and aimed at assessing the diversity of endohelminths in the invasive North African catfish Clarias gariepinus (Burchell, 1822) obtained from two freshwater lakes, Naivasha and Ol'Bolossat, in Kenya. Parasitological examination of 66 and 35 fish samples collected from the two lakes respectively was achieved using light and scanning electron microscopy methods. Results revealed endohelminth diversity broadly classified as four digeneans, two nematodes, and one cestode. Seven taxa of endohelminths were found in C. gariepinus samples, but only four of these taxa could be identified up to the species level. Six of the taxa (Diplostomum sp., Tylodelphys mashonense, Plagiorchioidea sp., Paracamallanus cyathopharynx, Contracaecum sp., and Tetracampos ciliotheca) were common in samples from the two lakes. Glossidium pedatum only occurred in samples from Lake Ol'Bolossat. Parasite prevalence ranged from 8.6 (T. mashonense) to 100% (Diplostomum sp., T. ciliotheca, and Contracaecum sp.) and mean intensity from 1.4 (T. mashonense) to 16.9 (Diplostomum sp.). The diversity and richness indices were comparatively higher in fish samples from Lake Ol'Bolossat and attributed to the occurrence of G. pedatum in the Ol'Bolossat. However, parasitic infestation of fish samples from the two lakes depicted close similarity, both in diversity and prevalence. These findings form an important baseline data for further follow-up studies, and they suggest the need for further molecular analyses to fully describe three of the taxa only identified up to the genus level.

New Triazolyl N

Cisplatin and other metallodrugs have realised great success in clinical chemotherapeutic applications as anticancer drugs. However, severe toxicity to healthy cells and non-selectivity to cancer cells remains a challenge, warranting the further search for alternative agents. Herein, we report the anticancer potential of a series of complexes of the general formula [MCl(p-cym)(k2-N^N-L)]+ X− and [MCl(Cp*)(k2-N^N-L)]+ X−, where M is the metal centre (Ru(II), Os(II), Rh(III) or Ir(III)), L = 1-benzyl-4-pyridinyl-1-H-1,2,3-triazole for L1 and 1-picolyl-4-pyridinyl-1-H-1,2,3-triazole for L2 and X− = Cl−, BF4−, BPh4−. When evaluated for activity against some cancerous and non-cancerous cell lines (namely, HeLa, HEK293, A549 and MT4 cancer cells and the normal healthy kidney cells (BHK21)), most of the compounds displayed poor cytotoxicities against cancer cells except for complexes C2 ([RuCl(p-cym)(k2-N^N-L1)]+ BPh4−, EC50 = 9−16 µM and SI = 14), C7 ([RuCl(p-cym)(k2-N^N-L2)]+ BPh4−, EC50 = 17−53 µM and SI = 4) and C11 ([IrCl(Cp*)(k2-N^N-L2)]+ BF4−, EC50 < 5 µM and SI > 10). Selected complexes C1 ([RuCl(p-cym)(k2-N^N-L1)]+ BF4−), C5 ([IrCl(Cp*)(k2-N^N-L1)]+ BF4−) and C11 showed significant interactions with model biomolecules such as guanosine-5'-monophosphate (5'-GMP), bovine serum albumin (BSA) and amino acids under physiological conditions, possibly through carbenylation and N-coordination with 5'-GMP, N-coordination with L-Histidine and L-proline. While the compounds showed good activities in reducing pyruvate to lactate, there was no direct correlation between catalytic transfer hydrogenation of pyruvate and the observed cytotoxic activities. As observed in this work, the marked influence of single atom replacement in ligand may provide a pivotal approach to improving the cytotoxicity and fine-tuning the selectivity to cancer cells.

A Novel Series of N-aryltriazole and N-acridinyltriazole Hybrids as Potential Anticancer Agents.

BACKGROUND: Triazoles are a class of aza-heterocycles with broad spectrum of biological importance. The synthetic tunability of the triazole moiety allows for the development of new pharmacophores with applications as drugs to contend with the burden of cancer. OBJECTIVE: In this study, we aimed to develop a series of N-aryltriazole and N-acridinyltriazole molecular hybrids and evaluate their potential as anticancer agents. METHODS: The triazole derivatives (1-10) were synthesized via a tandem nucleophilic substitution of aryl chlorides with sodium azide followed by 1,3-dipolar cycloaddition of the resulting organic azides with terminal/internal alkynes. From terminal alkynes, the well established copper(I) catalyzed azide-alkynes 1,3- dipolar cycloaddition, a premier example of click chemistry, was employed to access the 1,4-regioisomers of N-benzyl-1H-1,2,3-triazoles and N-acridynyl-1H-1,2,3-triazoles. All the compounds thus synthesized were characterized by 1D and 2D NMR spectroscopy and high resolution mass spectrometry. RESULTS: Thermally controlled 1,3-dipolar cycloaddition was used to deliver N-aryl-1H-1,2,3-triazoles with 1,4,5-substitution on the triazole framework. The unprecedented high regioselectivity promoted by the sterically-strained silylated 1,4,5-trisubstituted moiety 4a offers a useful synthetic precursor with the silyl group being a synthetic handle for further structural elaboration to the desired 1,(4),5-di(tri)substituted 1,2,3- triazoles. Notably, anticancer evaluation revealed good cytotoxic activities of the novel acridinyltriazole hybrids (6-10) at micromolar concentrations in the range of 12.5 µM-100 µM against cervical cancer HeLa, kidney cancer HEK293, lung cancer A549 and leukemic MT4 cancer cell lines (p < 0.05). CONCLUSION: A series of novel triazole-based acridine hybrids have been developed as potential leads for the development of multifaceted anticancer agents.