Procyanidins, as important secondary plant metabolites in fruits, berries, and beverages such as cacao and tea, are supposed to have positive health impacts, although their bioavailability is yet not clear. One important aspect for bioavailability is intestinal metabolism. The investigation of the microbial catabolism of A-type procyanidins is of great importance due to their more complex structure in comparison to B-type procyanidins. A-type procyanidins exhibit an additional ether linkage between the flavan-3-ol monomers. In this study two A-type procyanidins, procyanidin A2 and cinnamtannin B1, were incubated in the pig cecum model to mimic the degradation caused by the microbiota. Both A-type procyanidins were degraded by the microbiota. Procyanidin A2 as a dimer was degraded by about 80% and cinnamtannin B1 as a trimer by about 40% within 8 h of incubation. Hydroxylated phenolic compounds were quantified as degradation products. In addition, two yet unknown catabolites were identified, and the structures were elucidated by Fourier transform mass spectrometry.

From the organic extracts of two Guam sponges, Rhaphoxya sp., and Suberea sp., determined to have cytotoxic and chemopreventive activities, three new compounds, theonellin isocyanate (1), psammaplysins I and J (5-6), and six previously reported compounds (2-4, 7-9) were isolated and characterised spectroscopically (1H and 13C NMR, MS, IR, UV, [α]D). The two new compounds (5 and 6) isolated from the Rhaphoxya sp., sponge are rare examples of compounds containing a bromotyramine moiety rather than the more usual dibromo-analogue. For the compounds isolated from the Rhaphoxya sp., this is the first report of the known compounds 2-4 being found in a single sponge. For previously reported compounds 2-4 complete unambiguous 1H and 13C NMR data are provided.

The cancer chemopreventive and cytotoxic properties of 50 extracts derived from Twilight Zone (50–150 m) sponges, gorgonians and associated bacteria, together with 15 extracts from shallow water hard corals, as well as 16 fractions derived from the methanol solubles of the Twilight Zone sponge Suberea sp, were assessed in a series of bioassays. These assays included: Induction of quinone reductase (QR), inhibition of TNF-α activated nuclear factor kappa B (NFκB), inhibition of aromatase, interaction with retinoid X receptor (RXR), inhibition of nitric oxide (NO) synthase, inhibition 2,2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH), and inhibition of HL-60 and MCF-7 cell proliferation. The results of these assays showed that at least 10 extracts and five fractions inhibited NFκB by greater than 60%, two extracts and two fractions inhibited DPPH by more than 50%, nine extracts and two fractions affected the survival of HL-60 cells, no extracts or fractions affected RXR, three extracts and six fractions affected quinone reductase (QR), three extracts and 12 fractions significantly inhibited aromatase, four extracts and five fractions inhibited nitric oxide synthase, and one extract and no fractions inhibited the growth of MCF-7 cells by more than 95%. These data revealed the tested samples to have many and varied activities, making them, as shown with the extract of the Suberea species, useful starting points for further fractionation and purification. Moreover, the large number of samples demonstrating activity in only one or sometimes two assays accentuates the potential of the Twilight Zone, as a largely unexplored habitat, for the discovery of selectively bioactive compounds. The overall high hit rate in many of the employed assays is considered to be a significant finding in terms of “normal” hit rates associated with similar samples from shallower depths.

N-Nitroso compounds (NOC) are a group of compounds including N-nitrosamines and N-nitrosamides, which are well-known for their carcinogenic, mutagenic, and teratogenic properties. Humans can be exposed to NOC through the diet and environmentally, or NOC can be formed endogenously in the stomach and intestine. In the intestine, the formation of NOC is supposed to be afforded by the gut microbiota. In this study, the formation of the N-nitrosamines, N-nitrosomorpholine (NMOR) and N-nitrosopyrrolidine (NPYR), and the N-nitrosamides, N-nitrosomethylurea (NMU) and N-nitrosoethylurea (NEU), was investigated in the pig cecum model after the incubation of the corresponding precursor amine or amide with nitrite or nitrate. Following the incubation with nitrate, the formation of NMOR, NPYR, NMU, and NEU was detectable with the microbiota being responsible for the reduction of nitrate to nitrite. After the incubation of nitrite a chemical formation of NOC was shown.

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