Pregnane-10,2-carbolactones from a Hawaiian Marine Sponge in the Genus <i>Myrmekioderma</i>

Four new pregnanes, 3β,4β-dihydroxy-17-methyl-17α-pregna-5,13-diene-10,2-carbolactone (<b>1</b>), 6β-chloro-3β-hydroxy-17-methyl-17α-pregna-4,13-diene-10,2-carbolactone (<b>2</b>), 3β-hydroxy-6β-methoxy-17-methyl-17α-pregna-4,13-diene-10,2-carbolactone (<b>3</b>), and 3β,6β-dihydroxy-17-methyl-17α-pregna-4,13-diene-10,2-carbolactone (<b>4</b>), were isolated from an undescribed species of <i>Myrmekioderma</i> Ehlers along with the known pregnane carbolactone (<b>5</b>). The structures of the new compounds were determined by spectroscopic methods and comparison with previously described compounds. Compound <b>5</b> showed almost 4-fold activation of pregnane X receptor, while <b>2</b> inhibited BACE1 with an IC₅₀ value of 82 μM

Herbicidin Congeners, Undecose Nucleosides from an Organic Extract of <i>Streptomyces</i> sp. L‑9-10

Four new undecose nucleosides (herbicidin congeners), three known herbicidins, and 9-(β-d-arabinofuranosyl)­hypoxanthine (Ara-H) were isolated from the organic extract of a fermentation culture of <i>Streptomyces</i> sp. L-9-10 using proton NMR-guided fractionation. Their structures were elucidated on the basis of comprehensive 1D and 2D NMR and mass spectrometry analyses. These structures included 2′-<i>O</i>-demethylherbicidin F (<b>1</b>), 9′-deoxy-8′,8′-dihydroxyherbicidin B (<b>2</b>), 9′-deoxy-8′-oxoherbicidin B (<b>2a</b>), and the 8′-epimer of herbicidin B (<b>3</b>). This is the first detailed assignment of proton and carbon chemical shifts for herbicidins A, B, and F. The isolated compounds were evaluated for cancer chemopreventive potential based on inhibition of tumor necrosis factor alpha (TNF-α)-induced nuclear factor-kappa B (NF-κB) activity