A GNPS molecular networking approach mapped a library of 960 southern Australian marine sponges and prioritized Dysidea sp. (CMB-01171) for chemical investigation. Although the published natural products literature on Australian Dysidea sponges extends back over half a century and suffers from the perception of being near exhausted, fractionation of Dysidea sp. (CMB-01171) led to the discovery of a family of 10 new biosynthetically and chemically related sesquiterpenes. Detailed spectroscopic analysis guided structure elucidation identified dysidealactams A−F (1−6), dysidealactones A and B (7 and 8), and two solvolysis artifacts, 9 and 10. The dysidealactams A−D (1−4) incorporate a rare glycinyl-lactam functionality, while dysidealactam E ( 5) is particularly noteworthy in incorporating an unprecedented glycinyl-imide moiety. In addition to expanding knowledge of Dysidea natural products, this study demonstrates the value of applying GNPS molecular networking to map chemical diversity and prioritize the selection of marine sponge extracts for more detailed chemical analysis.

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Thorectandra choanoides (CMB-01889) was prioritized as a source of promising new chemistry from a library of 960 southern Australian marine sponge extracts, using a global natural products social (GNPS) molecular networking approach. The sponge was collected at a depth of 45 m. Chemical fractionation followed by detailed spectroscopic analysis led to the discovery of a new tryptophan-derived alkaloid, thorectandrin A (1), with the GNPS cluster revealing a halo of related alkaloids 1a–1n. In considering biosynthetic origins, we propose that Thorectandrachoanoides (CMB-01889) produces four well-known alkaloids, 6-bromo-1′,8-dihydroaplysinopsin (2), 6-bromoaplysinopsin (3), aplysinopsin (4), and 1′,8-dihydroaplysinopsin (10), all of which are susceptible to processing by a putative indoleamine 2,3-dioxygenase-like (IDO) enzyme to 1a–1n. Where the 1′,8-dihydroalkaloids 2 and 10 are fully transformed to stable ring-opened thorectandrins 1 and 1a–1b, and 1h–1j, respectively, the conjugated precursors 3 and 4 are transformed to highly reactive Michael acceptors that during extraction and handling undergo complete transformation to artifacts 1c–1g, and 1k–1n, respectively. Knowledge of the susceptibility of aplysinopsins as substrates for IDOs, and the relative reactivity of Michael acceptor transformation products, informs our understanding of the pharmaceutical potential of this vintage marine pharmacophore. For example, the cancer tissue specificity of IDOs could be exploited for an immunotherapeutic response, with aplysinopsins transforming in situ to Michael acceptor thorectandrins, which covalently bind and inhibit the enzyme.

Chemical analysis of a marine sponge, Cacospongia sp. (CMB-03404), obtained during deep sea commercial fishing activities off the southern coast of Australia, yielded an unprecedented family of sesterterpene α-methyl-γ-hydroxybutenolides, cacolides A–L (1–12), together with biosynthetically related norsesterterpene carboxylic acids, cacolic acids A–C (13–15). Structures were assigned on the basis of detailed spectroscopic analysis with comparisons to known natural products and biosynthetic considerations. In addition to revealing new chemical diversity, this study provided a valuable platform for comparing and contrasting the capabilities of the traditional dereplication technologies of HPLC-DAD, HPLC-MS and NMR, with those of the emerging HPLC-MS/MS approach known as global natural products social molecular networking (GNPS), as applied to marine sponge sesterterpene tetronic acids.

Bioactive 15Running title: Production of NF-κB suppressive bioactives by the human gut microbiota 16 Abstract 20Evidence is emerging that microbiome-immune system crosstalk regulates the tenor of host 21 intestinal immunity and predisposition to inflammatory bowel disease (IBD). We identified 22five NF-B suppressive strains affiliated with Clostridium clusters IV, XIVa and XV that 23 independently suppressed secretion of the chemokine IL-8 by peripheral blood mononuclear 24 cells and gut epithelial organoids from healthy human subjects, as well as patients with the 25 predominant IBD subtypes, Crohn's disease and ulcerative colitis. The NF-B suppressive 26Clostridium bolteae AHG0001, but not C. bolteae BAA-613, suppressed cytokine-driven 27 inflammatory responses and endoplasmic reticulum stress in gut epithelial organoids derived 28 from Winnie mice that develop spontaneous colitis. This predicted in vivo responses thereby 29 validating a precision medicine approach to treat Winnie colitis and suggesting the microbiome 30 may function as an extrinsic regulator of host immunity. Finally, we identified a novel 31 molecule associated with NF-B suppression indicating gut bacteria could be harnessed to 32 develop new therapeutics. 33Inflammatory bowel disease (IBD) is comprised of two predominant subtypes, termed Crohn's 41 disease (CD) and ulcerative colitis (UC), that are characterised by relapsing and remitting gut 42 3 inflammation. The Nuclear factor-B (NF-B) family of transcription factors are master 43 regulators of gut epithelial integrity and inflammation, activation of antigen presenting cells 44 and effector leukocytes, and are important contributors to the pathogenesis of IBD. Upon 45 activation, NF-B dimers translocate to the nucleus where they regulate transcription of a wide 46 range of genes including those involved in immune and inflammatory responses 6 . In the 47 healthy gut, NF-B activation is tightly regulated 7 however several IBD genetic risk alleles 48 including nod2, TOLLIP and A20 exert their pathogenic effects at least in part through 49 dysregulated NF-B signalling 8 . Additionally, CD disease phenotype correlates with NF-B 50 activation 9 , and macrophages and epithelial cells isolated from inflamed intestine of CD and 51 UC subjects show increased activation of nuclear NF-B-p65 10 . As such, NF-B signalling 52 contributes significantly to the cascade of host-responses underlying the pathogenesis of IBD. 53The gut microbiota is increasingly recognised as an important contributory risk factor for IBD. 54Underlying this, the healthy and IBD gut microbiota differ and are characterised by structure-55 function alterations to the microbiota 11 12 , and faecal transplantation has proven effective in 56 some patients with UC 13, 14 . Such findings suggest that key members of the microbiota regulate 57 host inflammatory responses. Indeed, several bacterial taxa are not only more abundant in the 58 healthy gut but can also suppress inflammatory responses and alleviate inflammation in an...