Lecanicilliums A-F, Thiodiketopiperazine-Class Alkaloids from a Mangrove Sediment-Derived Fungus Lecanicillium kalimantanense.

Six new thiodiketopiperazine-class alkaloids lecanicilliums A-F were isolated from the mangrove sediment-derived fungus Lecanicillium kalimantanense SCSIO41702, together with thirteen known analogues. Their structures were determined by spectroscopic analysis. The absolute configurations were determined by quantum chemical calculations. Electronic circular dichroism (ECD) spectra and the structure of Lecanicillium C were further confirmed by a single-crystal X-ray diffraction analysis. Lecanicillium A contained an unprecedented 6/5/6/5/7/6 cyclic system with a spirocyclic center at C-2'. Biologically, lecanicillium E, emethacin B, and versicolor A displayed significant cytotoxicity against human lung adenocarcinoma cell line H1975, with IC50 values of 7.2~16.9 µM, and lecanicillium E also showed antibacterial activity against four pathogens with MIC values of 10~40 µg/mL. Their structure-activity relationship is also discussed.

Anticandidal formyl phloroglucinol meroterpenoids: Biomimetic synthesis and in vitro evaluation.

Inspired by the diversity-oriented synthesis, some novel formyl phloroglucinol meroterpenoids were synthesized via biomimetic synthesis using essential oils. Eight of them were demonstrated with good in vitro fungicidal activity against Candida albicans and C. glabrata. Compound c2 showed the best anticandidal ability that was powerfully comparable to fluconazole when testing against several strains in vitro. The antibiofilm activity was also found for the c2 treating group which was evidenced to block the hyphal elongation and filamentation of C. albicans. Therefore, compound c2 is a promising candidate for further antifungal-based structure modification.