Inducing Secondary Metabolite Production by the Endophytic Fungus <i>Fusarium tricinctum</i> through Coculture with <i>Bacillus subtilis</i>

Coculturing the fungal endophyte <i>Fusarium tricinctum</i> with the bacterium <i>Bacillus subtilis</i> 168 trpC2 on solid rice medium resulted in an up to 78-fold increase in the accumulation in constitutively present secondary metabolites that included lateropyrone (<b>5</b>), cyclic depsipeptides of the enniatin type (<b>6</b>–<b>8</b>), and the lipopeptide fusaristatin A (<b>9</b>). In addition, four compounds (<b>1</b>–<b>4</b>) including (−)-citreoisocoumarin (<b>2</b>) as well as three new natural products (<b>1</b>, <b>3</b>, and <b>4</b>) were not present in discrete fungal and bacterial controls and only detected in the cocultures. The new compounds were identified as macrocarpon C (<b>1</b>), 2-(carboxymethylamino)­benzoic acid (<b>3</b>), and (−)-citreoisocoumarinol (<b>4</b>) by analysis of the 1D and 2D NMR and HRMS data. Enniatins B1 (<b>7</b>) and A1 (<b>8</b>), whose production was particularly enhanced, inhibited the growth of the cocultivated <i>B. subtilis</i> strain with minimal inhibitory concentrations (MICs) of 16 and 8 μg/mL, respectively, and were also active against <i>Staphylococcus aureus</i>, <i>Streptococcus pneumoniae</i>, and <i>Enterococcus faecalis</i> with MIC values in the range 2–8 μg/mL. In addition, lateropyrone (<b>5</b>), which was constitutively present in <i>F. tricinctum</i>, displayed good antibacterial activity against <i>B. subtilis</i>,<i> S. aureus</i>, <i>S. pneumoniae</i>, and <i>E. faecalis,</i> with MIC values ranging from 2 to 8 μg/mL. All active compounds were equally effective against a multiresistant clinical isolate of <i>S. aureus</i> and a susceptible reference strain of the same species

Unnatural Endotype B PPAPs as Novel Compounds with Activity against Mycobacterium tuberculosis

Pre-SARS-CoV-2, tuberculosis was the leading cause of death by a single pathogen. Repetitive exposure of Mycobacterium tuberculosis­(Mtb) supported the development of multidrug- and extensively drug-resistant strains, demanding novel drugs. Hyperforin, a natural type A polyprenylated polycyclic acylphloroglucinol from St. John’s wort, exhibits antidepressant and antibacterial effects also against Mtb. Yet, Hyperforin’s instability limits the utility in clinical practice. Here, we present photo- and bench-stable type B PPAPs with enhanced antimycobacterial efficacy. PPAP22 emerged as a lead compound, further improved as the sodium salt PPAP53, drastically enhancing solubility. PPAP53 inhibits the growth of virulent extracellular and intracellular Mtb without harming primary human macrophages. Importantly, PPAP53 is active against drug-resistant strains of Mtb. Furthermore, we analyzed the in vitro properties of PPAP53 in terms of CYP induction and the PXR interaction. Taken together, we introduce type PPAPs as a new class of antimycobacterial compounds, with remarkable antibacterial activity and favorable biophysical properties

Unnatural Endotype B PPAPs as Novel Compounds with Activity against Mycobacterium tuberculosis

Pre-SARS-CoV-2, tuberculosis was the leading cause of death by a single pathogen. Repetitive exposure of Mycobacterium tuberculosis­(Mtb) supported the development of multidrug- and extensively drug-resistant strains, demanding novel drugs. Hyperforin, a natural type A polyprenylated polycyclic acylphloroglucinol from St. John’s wort, exhibits antidepressant and antibacterial effects also against Mtb. Yet, Hyperforin’s instability limits the utility in clinical practice. Here, we present photo- and bench-stable type B PPAPs with enhanced antimycobacterial efficacy. PPAP22 emerged as a lead compound, further improved as the sodium salt PPAP53, drastically enhancing solubility. PPAP53 inhibits the growth of virulent extracellular and intracellular Mtb without harming primary human macrophages. Importantly, PPAP53 is active against drug-resistant strains of Mtb. Furthermore, we analyzed the in vitro properties of PPAP53 in terms of CYP induction and the PXR interaction. Taken together, we introduce type PPAPs as a new class of antimycobacterial compounds, with remarkable antibacterial activity and favorable biophysical properties

Cyclic Cystine-Bridged Peptides from the Marine Sponge <i>Clathria basilana</i> Induce Apoptosis in Tumor Cells and Depolarize the Bacterial Cytoplasmic Membrane

Investigation of the sponge <i>Clathria basilana</i> collected in Indonesia afforded five new peptides, including microcionamides C (<b>1</b>) and D (<b>2</b>), gombamides B (<b>4</b>), C (<b>5</b>), and D (<b>6</b>), and an unusual amide, (<i>E</i>)-2-amino-3-methyl-<i>N</i>-styrylbutanamide (<b>7</b>), along with 11 known compounds, among them microcionamide A (<b>3</b>). The structures of the new compounds were elucidated by one- and two-dimensional NMR spectroscopy as well as by high-resolution mass spectrometry. The absolute configurations of the constituent amino acid residues in <b>1</b>–<b>7</b> were determined by Marfey’s analysis. Microcionamides A, C, and D (<b>1</b>–<b>3</b>) showed <i>in vitro</i> cytotoxicity against lymphoma (Ramos) and leukemia cell lines (HL-60, Nomo-1, Jurkat J16), as well as against a human ovarian carcinoma cell line (A2780) with IC₅₀ values ranging from 0.45 to 28 μM. Mechanistic studies showed that compounds <b>1</b>–<b>3</b> rapidly induce apoptotic cell death in Jurkat J16 and Ramos cells and that <b>1</b> and <b>2</b> potently block autophagy upon starvation conditions, thereby impairing pro-survival signaling of cancer cells. In addition, microcionamides C and A (<b>1</b> and <b>3</b>) inhibited bacterial growth of <i>Staphylococcus aureus</i> and <i>Enterococcus faecium</i> with minimal inhibitory concentrations between 6.2 and 12 μM. Mechanistic studies indicate dissipation of the bacterial membrane potential