Matsulongifolins A-J: (-)-longifolane-type sesquiterpenoids from the mushroom Tricholoma matsutake (S. Ito & Imai) Singer.

The mushroom Tricholoma matsutake is renowned in East Asia for its distinctive flavour and nutritional value. However, its chemical composition remains largely unexplored. This study aimed to identify potential lead compounds from wild mushrooms, with a focus on the specialised metabolite profiles of T. matsutake. As a result, 10 rare (-)-(14-nor)longifolane-type sesquiterpenoids, designated matsulongifolins A-J (1-10), were isolated from the fruiting bodies of T. matsutake collected in the Tibet Autonomous Region, China. Matsulongifolins G (7)/H (8) and I (9)/J (10) were obtained as inseparable mixtures. The structures, including their absolute configurations, were determined through extensive spectroscopic analyses, single-crystal X-ray diffraction and electronic circular dichroism calculations. Matsulongifolin A (1) features a unique, rigid, cage-like 5/6/7/5/5 polycyclic system, while matsulongifolin B (2), an anhydride derivative, contains a 5/6/7/5 tetracyclic ring system. Matsulongifolins I (9) and J (10) are each distinguished by a succinyl group, a rare feature typically found in bacterial natural products. Bioassay results revealed that matsulongifolins B-F (2-6) exhibited weak inhibitory activity against Staphylococcus aureus subsp. aureus. This study represents the first identification of longifolane-type sesquiterpenes from a mushroom source and advances the understanding of the specialised metabolites present in T. matsutake.