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Five new sulfated arylpyrrole and arylpyrrolone alkaloids, denigrins H-L ( 1 - 5 ), along with two known compounds, dictyodendrin B and denigrin G, were isolated from an extract of a New Zealand Dictyodendrilla c.f. dendyi marine sponge. Denigrins H-L represent the first examples of sulfated denigrins , with denigrins H and I ( 1 - 2 ), as derivatives of denigrin D, containing a pyrrolone core, and denigrins J-L ( 3 - 5 ), as derivatives of denigrin E ( 6 ), containing a pyrrole core. Their structures were elucidated by interpretation of 1D and 2D NMR spectroscopic data, ESI, and HR-ESI-MS spectrometric data, as well as comparison with literature data. Compounds 1-5 , along with six known compounds previously isolated from the same extract, showed minimal cytotoxicity against the HeLa cervical cancer cell line.

Feeding-choice experiments were conducted under laboratory conditions with two dorid spongivorous nudibranchs, Goniobranchus aureomarginatus and Ceratosoma amoenum, collected from a sponge meadow off Tauranga, New Zealand with two sponge prey (Dysidea teawanui sp.nov. and an undescribed species from the Dictyodendrillidae family, possibly Dictyodendrilla tenella (Lendenfeld 1888). The first choice of prey, the total number of prey choices made, and the time spent on each prey target was recorded, results indicating that each nudibranch had strong preferences for specific prey species. Preferences were significant when the time spent grazing on prey was taken into consideration. Goniobranchus aureomarginatus had a strong preference for the undescribed Dictyodendrillid sponge, while Ceratosoma ameonum preferred Dysidea teawanui. The results of the feeding-choice experiments matched observations in the wild. Chemical analysis of the undescribed Dictyodendrillid sponge led to the isolation and characterisation of six known bioactive metabolites, dictyodendrin C (1), D (2) and F (3), as well as denigrin E (4), dactylpyrrole A (5) and lamellarin O1 (6). Two of the known compounds, dictyodendrins C (1) and F (3) were also isolated from G. aureomarginatus individuals. Chemical analysis of D. teawanui afforded ergosterol peroxide, 5α,8α-epidioxy-24-methylcholesta-6,22-dien-3β-ol (7). The structures of the isolated natural products were elucidated based on extensive analysis of 1D and 2D NMR data., (© 2023. The Author(s).)

Antimicrobial bioassay-guided fractionation of Microcera larvarum led to the isolation of a γ-lactone with a furo[3,4- b ]pyran-5-one bicyclic ring system ( 1 ) and three known compounds, (3 S ,4 R )-4-hydroxymellein ( 2 ), (3 S ,4 S )-4-hydroxymellein ( 3 ) and 7-hydroxy-3-(1-hydroxyethyl)isobenzofuran-1(3 H )-one ( 4 ). Structure elucidation was conducted by NMR spectroscopic methods. Absolute configuration of 1 (2 R , 3 S , 5 S , 7 S, 8 R ) was established using the chiral derivatizing agent MPA and was fully supported by calculated specific rotation and ECD spectra. The spectroscopic data observed for 1 were identical to those previously reported for theissenolactone A ( 7 ), necessitating a correction of the latter (from C-5/C-8 trans ring fusion to cis ). Compounds 1 - 4 were evaluated for antimicrobial activity against a panel of pathogens.