Our interest in the red alga Delisea pulchra (=D.fimbriata) (Greville) Montagne 1844 (Rhodophyceae, Bonnemaisoniales, Bonnemaisoniaceace) was stimulated by its activity in the biosssays done at Wyeth Pharmaceuticals. Halogenated compounds from D. pulchra interfere with Gram-negative bacterial signaling systems, affect the growth of Gram-positive bacteria, inhibit quorum sensing and swarming motility of marine bacteria (inhibit bacterial communication). They also inhibit surface colonization in marine bacteria and exhibit antifouling properties against barnacle larvae and macroalgal gametes. Chemical investigation of D.pulchra collected near Palmer Station, Antarctica yielded three new dimeric halogenated furanones, pulchralide A-C (41-43), along with previously reported fimbrolide (21), acetoxyfimbrolide (22), hydroxyfimbrolide (23) and halogenated ketone 40. The reported Compounds were characterized by comparison of their 1H and 13C NMR data with that previously published. Pulchralide A-C were characterized by both 1D (1H NMR, 13C NMR, DEPT, 1H-1H COSY) and 2D (gHMQC, gHMBC) NMR techniques, supported by HREIMS/HRESIMS data. The absolute stereochemistry of Pulchralide A was determined by a single crystal X-ray analysis. Significant antimicrobial activity was observed in acetoxyfimbrolide (22) and hydroxyfimbrolide (23), where as pulcharlide A (41) and fimbrolide (21) were weakly active.

Disinfectants in drinking water can interact with natural organic matter (NOM) to form disinfection by-products (DBPs). Halogenated furanones (including MX and MCA) are a group of emerging DBPs that can account for a significant amount of the total mutagenicity found in drinking water. Source water characteristics and NOM removal capabilities of coagulation can greatly influence the formation of DBPs. This project examines the effects of bench scale coagulation and chlorination tests on NOM removal, DBP formation, and genotoxicity. NOM was characterized using liquid chromatography-organic carbon detection (LC-OCD). Experiments with Ottawa River, Otonabee River, and Lake Simcoe waters show that DBPs decreased with increases in coagulant dosage, due to the removal of NOM during coagulation. DBP formation and speciation was then compared with NOM content to identify specific fractions that contribute to the formation of these DBPs. Genotoxicity was directly linked to MX presence in chlorinated waters.