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Four new spirobenzylisoquinoline mucroniferanines N - Q (1-4) and a rare chlorinated isoquinoline mucroniferanine R (5) were isolated from Corydalis mucronifera Maxim. Their structures were elucidated based on extensive spectroscopic data analysis of HRESIMS, 1D and 2D NMR, and their absolute configurations were confirmed by ECD data. The isolated compounds were evaluated for acetylcholinesterase (AChE) inhibitory activities. Mucroniferanine R showed significant activities with IC 50 values of 0.78 μM compared to galanthamine (1.34 μM). The AChE inhibitory activity was further supported by the molecular docking analysis that exhibited the accommodation of mucroniferanine R in the active site of human AChE., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Endophytic fungi is an important source for the discovery of bioactive natural compounds. A chemical investigation of the ethyl acetate extract of the endophytic fungus Schizophyllum sp. HM230 derived from stems of the herb Vincetoxicum mongolicum Maxim led to isolation of five alkaloids, including two new compounds, schizophyllins M ( 1 ) and N ( 2 ), along with three known ones ( 3 - 5 ). The planar structures of two new compounds were elucidated by extensive spectroscopic methods including MS, 1D and 2D NMR. Their absolute configurations were determined by Mosher's method and comparison of the ECD data. All the isolates were evaluated for their cytotoxicity and antioxidant activities. Compounds 1 - 4 showed middle cytotoxicity against MCF-7 cells with IC 50 values range of 68.1 ∼ 87.32 μM. Compounds 1 - 5 displayed obvious antioxidant activity with the IC 50 values range of 0.86 ∼ 5.78 mg/mL.

Diketopiperazine alkaloids have proven the most abundant heterocyclic alkaloids up to now, which usually process diverse scaffolds and rich biological activities. In our search for bioactive diketopiperazine alkaloids from marine-derived fungi, two novel diketopiperazine alkaloids, penipiperazine A (1) and its biogenetically related new metabolite (2), together with a known analogue neofipiperzine C (3), were obtained from the strain Penicillium brasilianum. Their planar structures and absolute configurations were elucidated by extensive spectroscopic analyses, 13 C NMR calculation, Marfey's, ECD, and ORD methods. Compound 1 featured a unique 6/5/6/6/5 indole-pyrazino-pyrazino-pyrrolo system, and its plausible biogenetic pathway was also proposed. Additionally, compounds 1-3 have been tested for their inflammatory activities. 1 and 2 significantly inhibited the release of NO and the expression of related pro-inflammatory cytokines on LPS-stimulated RAW264.7 cells, suggesting they could be attracting candidate for further development as anti-inflammatory agent. KEY POINTS: • A novel diketopiperazine alkaloid featuring a unique 6/5/6/6/5 indole-pyrazino-pyrazino-pyrrolo system was isolated from the marine fungus Penicillium brasilianum. • The structure of 1 was elucidated by detailed analysis of 2D NMR data, 13 C NMR calculation, Marfey's, ECD, and ORD methods. • Compounds 1 and 2 significantly inhibited the release of NO and the expression of related pro-inflammatory cytokines on LPS-stimulated RAW264.7 cells., (© 2024. The Author(s).)