Investigation of the Dietary Preferences of Two Dorid Nudibranchs by Feeding-Choice Experiments and Chemical Analysis

Abstract

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.

Denigrins H–L: Sulfated Derivatives of Denigrins D and E from a New Zealand Dictyodendrilla c.f. dendyi Marine Sponge

“…dendyi extract, with denigrin G isolated as a mixture with dactylpyrrole A, previously reported from the D. c.f. dendyi extract [9]. Both known compounds displayed NMR and ESI-MS spectroscopic data matching closely with literature values [10,11].…”

“…Following this study, we further investigated the D. c.f. dendyi methanol/dichloromethane crude extract, with a focus on the minor compounds, and wish to report the isolation and structure elucidation of denigrins H-L (1-5), five new sulfated derivatives of either denigrin D or E, as well as two known compounds, dictyodendrin B and denigrin G. The 13 C NMR assignments and spectrum of denigrin E (6) in CD3OD are also reported, due to compounds 3-5 being closely related to 6, which was previously fully characterized in pyridine-d5 [5], with only the 1 H NMR spectrum reported in CD3OD [9].…”

“…Feeding-choice experiments indicated a strong preference for D. c.f. dendyi [9]. The predator-prey relationship was further established by isolating six known alkaloids, dictyodendrins C, D, and F, denigrin E, dactypyrrole We have previously investigated the New Zealand nudibranch Goniobranchus aureomarginatus and its feeding preferences, utilizing two marine sponges, Dysidea teawanui sp.…”

“…Feeding-choice experiments indicated a strong preference for D. c.f. dendyi [9]. The predator-prey relationship was further established by isolating six known alkaloids, dictyodendrins C, D, and F, denigrin E, dactypyrrole A, and lamellarin O1 from D. c.f.…”

“…The predator-prey relationship was further established by isolating six known alkaloids, dictyodendrins C, D, and F, denigrin E, dactypyrrole A, and lamellarin O1 from D. c.f. dendyi, with dictyodendrins C and F also isolated from the nudibranch extract [9]. Following this study, we further investigated the D. c.f.…”