Sadopeptins A and B, Sulfoxide- and Piperidone-Containing Cyclic Heptapeptides with Proteasome Inhibitory Activity from a Streptomyces sp

Chemical Composition, Antioxidant and Anti-Inflammatory Activity of Shiitake Mushrooms (Lentinus edodes)

Shiitake mushrooms (Lentinus edodes) are renowned as the "King of mountain treasures" in China due to their abundant nutritional and health-enhancing properties. Intensive chemical investigations of the fruiting bodies and mycelium of Shiitake mushrooms (Lentinus edodes) afforded five new compounds (1-5), named lentinmacrocycles A-C and lentincoumarins A-B, along with fifteen known compounds (6-20). Their structures and absolute configurations were elucidated by extensive spectroscopic analysis, including one-and two-dimensional (1D and 2D) NMR spectroscopy, circular dichroism (CD), and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). The anti-inflammatory activity test showed that lentincoumarins A (4), (3S)-7-hydroxymellein (9), (3R)-6-hydroxymellein (11) and succinic acid (18) exhibited strong NO inhibitory effects (IC50 < 35 μM), and that (3S)-5-hydroxymellein (10) and (3R)-6-hydroxymellein (11) exhibited potent TNF-α inhibitory effects (IC50 < 80 μM) and were more potent than the positive control, Indomethacin (IC50 = 88.5 ± 2.1 μM). The antioxidant activity test showed that (3R)-6-hydroxymellein (11) had better DPPH radical scavenging activity (IC50 = 25.2 ± 0.5 μM).

Isolation and structure determination of a new depsipeptide crocapeptin C from the myxobacterium Melittangium boletus

A new cyclic depsipeptide, crocapeptin C (1), containing 3-amino-6-hydroxy-2-piperidone (Ahp) was isolated from the methanol extract of the myxobacterium Melittangium boletus. The chemical structure of crocapeptin C (1) was determined through NMR and ESI-MS analysis. The stereochemistries of the constituent amino acids in crocapeptin C (1) were determined using the advanced Marfey's method and ROESY spectrum data. Crocapeptin C (1) exhibited potent inhibitory activity against chymotrypsin with an IC50 value of 0.5 µM.