Gastric cancer is among the major causes of death from neoplasia leading causes of death worldwide, with high incidence rates and problems related to its treatment. Here, we outline how Geissospermum sericeum exerts antitumor activity on the ACP02 cell line (human gastric adenocarcinoma) and the mechanism of cell death. The ethanol extract and fractions, neutral fraction and alkaloid fraction, were characterized by thin-layer chromatography and HPLC-DAD, yielding an alkaloid (geissoschizoline N4-methylchlorine) identified by NMR. The cytotoxicity activity of the samples (ethanol extract, neutral fraction, alkaloid fraction, and geissoschizoline N4-methylchlorine) in HepG2 and VERO cells was determined by MTT. The ACP02 cell line was used to assess the anticancer potential. Cell death was quantified with the fluorescent dyes Hoechst 33342, propidium iodide, and fluorescein diacetate. The geissoschizoline N4-methylchlorine was evaluated in silico against caspase 3 and 8. In the antitumor evaluation, there was observed a more significant inhibitory effect of the alkaloid fraction (IC50 18.29 µg/mL) and the geissoschizoline N4-methylchlorine (IC₅₀ 12.06 µg/mL). However, geissoschizoline N4-methylchlorine showed lower cytotoxicity in the VERO (CC₅₀ 476.0 µg/mL) and HepG2 (CC₅₀ 503.5 µg/mL) cell lines, with high selectivity against ACP02 cells (SI 39.47 and 41.75, respectively). The alkaloid fraction showed more significant apoptosis and necrosis in 24 h and 48 h, with increased necrosis in higher concentrations and increased exposure time. For the alkaloid, apoptosis and necrosis were concentration- and time-dependent, with a lower necrosis rate. Molecular modeling studies demonstrated that geissoschizoline N4-methylchlorine could occupy the active site of caspases 3 and 8 energetically favorably. The results showed that fractionation contributed to the activity with pronounced selectivity for ACP02 cells, and geissoschizoline N4-methylchlor is a promising candidate for caspase inhibitors of apoptosis in gastric cancer. Thus, this study provides a scientific basis for the biological functions of Geissospermum sericeum, as well as demonstrates the potential of the geissoschizoline N4-methylchlorine in the treatment of gastric cancer.

The present work reports the isolation and biological evaluation of three dimeric xanthones from Paecilomyces sp. EJC01.1 isolated as endophytic from Schnella splendens, a typical plant of the Amazon. The compounds phomoxanthone A (1), phomoxanthone B (2) and dicerandrol B (3) were isolated by chromatographic procedures and identified by spectroscopic methods of 1D and 2D NMR and MS. The extracts and compound 1 showed antimicrobial activities against Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and Pseudomonas aeruginosa. The compound phomoxanthone A (1) showed greater inhibitory activity against B. subtilis (MIC of 7.81 µg mL⁻¹); in addition, it also pronounced inhibitory effect against promastigote forms of Leishmania amazonensis (IC₅₀ of 16.38 ± 1.079 µg mL⁻¹) and epimastigote forms Trypanosoma cruzi (IC₅₀ of 28.61 ± 1.071 µg mL⁻¹). To provide more information about the antibacterial activity of compound 1, an unprecedented molecular docking study was performed using S-ribosyl-homocysteine lyase (LuxS) (PDB ID 2FQO), which showed a possible interaction of phomoxanthone A with two of the residues (His58 and Cys126) that are fundamental for the catalysis mechanism in B. subtilis, which may be associated with the higher activity, when compared to other bacteria, observed in experimental studies. Additionally, quantum studies (DFT) were performed, for which a low gap value (5.982 eV) was observed, which corroborates the reactivity of phomoxanthone A. Thus, phomoxanthone A can be a good agent against pathogenic bacteria.

Biotransformations are reactions mediated by microorganisms, such as fungi. These bioreactions have high chemo- and stereoselectivity on organic substrates and can be applied in the search for new bioactive compounds. In this study, acanthoic acid (AA) was biotransformed using the fungus Xylaria sp., giving the novel compound 3β,7β-dihydroxyacanthoic acid (S1). Both the AA and the product S1 were tested against Gram-positive and Gram-negative bacteria. To identify and validate possible biological targets as enzymes or proteins involved in the activity observed in vitro, we used the molecular docking method. Hydroxylation at the C-3 and C-7 positions of the biotransformation product enhanced its activity against Escherichia coli as well as its binding affinity and interactions with superoxide dismutase 1 (SOD1; PDB ID 4A7G). Based on our results, the SOD1 enzyme was suggested to be a possible target for the antioxidant activity of product S1.

The search for bioactive compounds for the treatment of several diseases has led to the study of endophytic fungi. Neoplastic diseases are among the most significant health concerns due to their high mortality rate, and there is a dearth of efficacious pharmaceutical agents for the treatment of cancer. Gastric cancer is one of the most aggressive forms of cancer and is among those with the highest mortality rates in Brazil. Accordingly, the objective of this study was to identify compounds with cytotoxic activity from the mangrove-derived endophytic fungus Trichoderma sp. Isolation of the chemical compounds was conducted using chromatographic methods, while structural elucidation was achieved through the application of spectroscopic (NMR and UV) and spectrometric (MS) techniques. The fungus Trichoderma sp. was found to produce five distinct koninginins (A, B, C, E, and J). The organic phases of the extracts and isolated compounds were evaluated for their antimicrobial and cytotoxic potentials, respectively, through microdilution testing and the MTT method. In the cytotoxicity assay, both the AF extract and koninginin A demonstrated favorable outcomes, indicating their potential as promising anticancer therapeutic agents.

Bacterial spot, which is the main disease occurring in passion fruit trees, is caused by the bacterium Xanthomonas axonopodis pv. passiflorae, leading to large annual losses in passion fruit crops. This study aims to find extracts and/or bioactive compounds of endophytic fungi of noni (Morinda citrifolia) to treat bacterial spot in passion fruit trees. Nine fungi isolated from a specimen of M. citrifolia from the Brazilian Amazon are studied. The fungus Guignardia mangiferae NF17 shows the best inhibition results and is selected for the isolation of its secondary metabolites by chromatography techniques. The isolated compounds Sydowinol (S1) and Sydowinin A (S2) are identified by nuclear magnetic resonance (NMR). Compounds S1 and S2, as well as the acetonitrile extract from the biomass of G. mangiferae NF17, are tested against four strains of X. axonopodis pv. passiflorae obtained from plants infected by bacterial spot, and which inhibited bacterial growth up to the lowest concentration tested (3.125 µg/mL). This study reports, for the first time, the antibacterial activity against X. axonopodis pv. passiflorae by the compounds Sydowinol and Sydowinin A. Compounds S1 and S2 are reported for the first time for the genus Gignardia.

The search for bioactive compounds for the treatment of several diseases has led to the study of endophytic fungi. Neoplastic diseases are among the most significant health concerns due to their high mortality rate, and there is a dearth of efficacious pharmaceutical agents for the treatment of cancer. Gastric cancer is one of the most aggressive forms of cancer and is among those with the highest mortality rates in Brazil. Accordingly, the objective of the present study was to identify compounds with cytotoxic activity from the mangrove-derived endophytic fungus Trichoderma sp. Isolation of the chemical compounds was conducted using chromatographic methods, while structural elucidation was achieved through the application of spectroscopic (NMR and UV) and spectrometric (MS) techniques. The fungus Trichoderma sp. was found to produce five distinct koninginins (A, B, C, E, and J). The organic phases of the extracts and isolated compounds were evaluated for their antimicrobial and cytotoxic potentials, respectively, through microdilution testing and the MTT method. In the cytotoxicity assay, both the AF extract and koninginin A demonstrated favorable outcomes, indicating their potential as promising anticancer therapeutic agents.