This study evaluated the antimicrobial and antioxidant activities of crude peptide extracted from Galatea paradoxa (G. paradoxa) and Patella rustica (P. rustica). The extracts were tested against eight strains of bacteria (Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Salmonella typhi, Enterococcus feacalis, Klebseilla pneumoniae, Streptococcus pneumoniae, Pseudomonas aeruginosa) and one strain of fungi (Candida albicans) using agar well diffusion and broth dilution assays. The extracts from G. paradoxa demonstrated a high degree of activity against the bacteria strains but were inactive towards the fungus. P. rustica, however, showed a markedly higher antifungal activity but little antibacterial effect. The minimum inhibitory concentrations (MIC) of the extracts determined by the broth tube dilution assay were 17 mg/mL of G. paradoxa against the entire spectrum of microorganisms tested except for C. albicans which was 20 mg/mL. The MIC of the extracts of P. rustica was 13 mg/mL against all the strains of microorganisms tested except for E. feacalis (17 mg/mL), K. pneumoniae (17 mg/mL) and C. albicans (13 mg/mL). Antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay showed scavenging ability on the DPPH radical was 56.77 % at 0.39 mg/mL for G. paradoxa and 79.77 % at 0.39 mg/mL for P. rustica. The study indicates that the crude peptide extracts from the two molluscs have promising antimicrobial and antioxidant activities that can be harnessed as leads for potential bioactive compounds.

Hydrogenation of CO2 to formate serves as a means of H2 storage. By utilizing robust, electron-rich and bulky N∧N bidentate tetrazolylpyridyl ligands, we have prepared CO2 hydrogenation iridium­(III) and palladium­(II) catalyst precursors (3–7) that operate in water as a solvent. In situ 1H NMR spectroscopic data obtained when the hydrogenation catalyst is 5 detect that a hydrido-bridged binuclear iridium intermediate compound is formed prior to the formation of the catalytically active iridium hydride species. This hydrido-bridged iridium intermediate is observable by in situ 1H NMR spectroscopy even after extended periods of storage. In addition, we demonstrate that product formation in the CO2 hydrogenation, catalyzed by these tetrazolylpyridyl iridium catalysts, proceeds via either CO2 hydrogenation or NaHCO3 reduction.

Pyrazole-containing compounds have been used in recent times as ligands to stabilize metal complexes used as pre-catalysts in cross-coupling reactions.

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