Background: The fractionation of the n-hexane phase of the EtOH extract from the leaves of Duguetia lanceolata (Annonaceae) led to the identification of the sesquiterpene (–)-cyclocolorenone. Objectives: Chemical characterization, including determination of the absolute stereochemistry, and in vitro evaluation of antileishmanial activity of the sesquiterpene (–)-cyclocolorenone, isolated from D. lanceolata, were carried out. Methods: (–)-Cyclocolorenone was isolated from D. lanceolata leaves using different chromatographic steps and its structure was defined by analysis of NMR and ESI-HRMS data. Additionally, the absolute configuration of (–)-cyclocolorenone was ambiguously assigned by means of vibrational circular dichroism (VCD). Antileishmanial activity of (–)-cyclocolorenone was evaluated on promastigote and amastigote forms of Leishmania (Leishmania) amazonensis. The integrity of the cell membrane of L. (L.) amazonensis was analyzed using the SYTOX green probe. Results: (–)-(1R,6S,7R,10R)-Cyclocolorenone displayed activity against promastigotes and amastigotes forms of L. (L.) amazonensis with IC₅₀ of 4.54 and 28.44 µM, respectively. Furthermore, this compound was non-toxic in J774 macrophage cells (CC₅₀ > 458.71 µM) with a selectivity index > 100 (promastigotes) and > 32.2 (amastigotes). Additionally, (–)-cyclocolorenone was observed to target the parasite cell membrane. Conclusion: Obtained data suggested that (–)-cyclocolorenone, in which absolute configuration was determined, can be considered as a scaffold for the development of new drugs for the treatment of leishmaniasis.

Endophytic fungi are increasingly being recognized for their diverse metabolites that may exhibit antimicrobial properties. In our study, we isolated seven endophytic fungal strains from Calea pinnatifida, which were identified as Hypomontagnella barbarensis, Neopestalotiopsis clavispora, Nigrospora sacchari-officinarum, Annulohypoxylon moriforme, Colletotrichum siamense, and Colletotrichum karstii (with two isolates from the same species). Furthermore, the antimicrobial activity of the extracts was assessed, revealing that the extract from Hypomontagnella barbarensis demonstrated activity against Staphylococcus aureus. Further investigation of secondary metabolites, employing UHPLC-HR-ESI-MS/MS in combination with molecular networking, facilitated annotation of the nine compounds. Of these, five were identified based on matches with the GNPS spectral library, and four were predicted based on the molecular network. Notably, from the extract of Hypomontagnella barbarensis, two pairs of diastereoisomeric acyl-tetronic acid derivatives were isolated and characterized using MS and NMR spectroscopy. This study highlights the potential of endophytic fungi as a valuable source of novel antimicrobial agents.

Almost fifty years after the introduction of antibiotics as an antimicrobial agent, we are facing an increasing number of multi-resistant microbials. The search for new antimicrobial compounds emerged as a promising alternative to treatments for diseases caused by microorganisms such as fungi and bacteria. Thus, endophytic fungi are gaining recognition for their varied metabolites that may possess antimicrobial properties. In our research, we isolated, from Calea pinnatifida, six endophytic fungi identified as Colletotrichum siamense, Colletotrichum karstii, Hypomontagnella barbarensis, Neopestalotiopsis clavispora, Nigrospora sacchari-officinarum and Annulohypoxylon moriforme. Analyses of microbial secondary metabolites by utilizing UHPLC-HR-ESI-MS/MS in conjunction with molecular networking, allowed the annotation of 9 compounds, 5 of them from GNPS spectral library match, and 4 from prediction-based on the molecular network, and allowed the isolation of two pairs of Acyl-tetronic acid derivatives distereoisomeric identified by NMR spectrum. In this sense, the present study underlines the value of endophytic fungi as a reservoir of potentially new antimicrobial agents.