| Summary: | Marine bryozoans is a prolific source of structurally diverse bioactive secondary metabolites. However, the total number of natural products isolated from marine bryozoans is limited, The present study was focused on isolation and characterization of new compounds from Arctic marine bryozoans. The novel compounds were isolated by using two different approaches. For bioassay-guided isolation, fractions of an extract of the Arctic bryozoan Securiflustra securifrons were screened for anticancer activity. The active fractions were analyzed by UPLC-HR-MS, and the elemental composition of the target compound was determined and dereplicated. The structure of the isolated compound, securidine A, was elucidated by 1D and 2D NMR spectroscopic techniques. Securidine A was evaluated for its bioactivity in various bioassays including anticancer activity, antibacterial, antidiabetic and the ability to inhibit the biofilm formation, but no bioactivity was observed. Fractions of the organic extract of S. securifrons were screened for antibacterial activity. The chemical analysis of the active fraction revealed that it contained several securamines along with securidine A. The pure compounds securamines C, E, H-J were tested against G + and G – pathogenic bacteria and their ability to inhibit biofilm formation was studied. Among these, securamine H was active against B. subtilis and the mode of action studies revealed that securamine H reduced the metabolic activity of B. subtilis but no interference with bacterial intracellular metabolic processes were found. To address any synergistic interactions, the minor compound securamine H and the major compound securidine A were assayed together, but no effect was observed. A new secondary metabolite, dendrobeaniamine A was isolated from the Arctic bryozoan Dendrobeania murrayana through chemistry-guided isolation. A chemical analysis of the organic crude extract of D. murryana, led to the isolation of fattyamino acid molecule, dendrobeaniamine A. The protonated elemental composition of the target compound was calculated and dereplicated. The structure was solved by various 1D and 2D NMR spectroscopic methods. The bioactivity of dendrobeaniamine A was evaluated using cellular and biochemical assays, such as antimicrobial, anti-inflammatory and antioxidant activities, but no activity was found.
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