Induction of ambuic acid derivatives by the endophytic fungus Pestalotiopsis lespedezae through an OSMAC approach

Caryophyllene-type sesquiterpenes from the endophytic fungus Pestalotiopsis lespedezae through an OSMAC approach

Two new caryophyllene-type sesquiterpenes pestalotiopsins U and V (1 and 2) and three known compounds pestalotiopsin B (7), pestaloporinate B (8), and pestalotiopsin C (9) were isolated by the cultivation of the endophytic fungus Pestalotiopsis lespedezae on solid rice medium, while four additional new caryophyllene pestalotiopsins W-Z (3-6) were obtained when 3.5% NaI was added to the fungal culture medium. The structures of the new compounds were determined by HRESIMS and 1D/2D nuclear magnetic resonance data. Compounds 1-9 were tested for cytotoxicity against the mouse lymphoma cell line L5178Y, but only 6 displayed significant activity with an IC50 value of 2.4 μM.

Bioactive ambuic acid congeners from endophytic fungus Pestalotiopsis trachicarpicola SC-J551

New ambuic acid derivatives, pestallic acids R-V (1-5), together with ambuic acid (6), were isolated from the endophytic fungus Pestalotiopsis trachicarpicola SC-J551 derived from the fern Blechnum orientale L., of which compound 2, being racemic, was separated to two optically pure enantiomers (+)-2 and (-)-2. The structures including absolute configurations of these new compounds were elucidated by extensive spectroscopic analysis and theoretical simulations of their ECD spectra and 13C NMR chemical shifts. Compounds 1 and 3 exhibited cytotoxicity against human carcinoma A549, HeLa, HepG2, and MCF-7 cells (IC50: 3.6-12.5 μM) and compound 3 was also active against Staphylococcus aureus and MRSA (MIC = 20 μg ml-1). Compound (±)-2 showed inhibitory activity against LPS-induced NO release (IC50 = 21.1 μM) and t-BHP-induced ROS production (IC50 = 8.5 μM) in RAW264.7 macrophages.

Natural epoxyquinoids: isolation, biological activity and synthesis. An update

Epoxyquinoids are of continuing interest due to their wide natural distribution and diverse biological activities, including, but not limited to, antibacterial, antifungal, anticancer, enzyme inhibitory, and others. The last review on their total synthesis was published in 2017. Since then, almost 100 articles have been published on their isolation from nature and their biological profile. In addition, the review specifically considers synthesis, including total and enantioselective, as well as the development of shorter approaches for the construction of epoxyquinoids with complex chemical architecture. Thus, this review focuses on progress in this area in order to stimulate further research.

The Discovery and Structure-Activity Evaluation of (+)-Floyocidin B and Synthetic Analogs

Tuberculosis represents one of the ten most common courses of death worldwide and the emergence of multidrug‐resistant M. tuberculosis makes the discovery of novel anti‐tuberculosis active structures an urgent priority. Here, we show that (+)‐floyocidin B representing the first example of a novel dihydroisoquinoline class of fungus‐derived natural products, displays promising antitubercular hit properties. (+)‐Floyocidin B was identified by activity‐guided extract screening and its structure was unambiguously determined by total synthesis. The absolute configuration was deduced from a key synthesis intermediate by single crystal X‐ray diffraction analysis. A hit series was generated by the isolation of further natural congeners and the synthesis of analogs of (+)‐floyocidin B. Extensive biological and physicochemical profiling of this series revealed first structure‐activity relationships and set the basis for further optimization and development of this novel antitubercular scaffold.