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The protective and growth-promoting activities of Colletrotrichum and Diaporthe endophytes on tomato plants (Lycopersicon esculentum Mill.) are underexplored. We screened 40 endophytic fungi associated with Mexican shrimp plant (Justicia brandegeana) using an in vitro dual culture assay for Fusarium oxysporum, one of the most important phytopathogens of tomato plants. The three best antagonists, Colletotrichum siamense (JB224.g1), C. siamense (JB252.g1), and Diaporthe masirevicii (JB270), were identified based on multilocus sequence analysis. They were assessed in vitro for their inhibition of F. oxysporum and phosphate solubilisation capacity, and for the production of indole acetic acid. Greenhouse experiments verified the growth-promoting effects of these endophytes and the suppression of F. oxysporum symptoms in tomato plants. Under greenhouse conditions, the JB252.g1 and JB270 isolates showed positive results for seedling emergence speed. The radicular system depth of plants inoculated with JB270 was greater than that in uninoculated plants (27.21 vs 21.95 cm). The soil plant analysis development chlorophyll metre (SPAD) index showed statistically significant results, especially for the endophyte JB224.g1 (36.99) compared to the control plants (30.90) and plants infected solely with F. oxysporum (33.64).

In the present study, the biological activity of an extract of the secondary metabolites (E-G6-32) produced by the Curvularia sp. G6-32 endophyte (isolated from the medicinal plant Sapindus saponaria L.) was investigated. The antioxidant potential was confirmed by the DPPH (22.5%) and ABTS (62.7%) assays, and the total phenolic compound content was 40 µg gallic acid equivalents/mg. The extract E-G6-32 displayed good inhibitory activity toward butyrylcholinesterase (BuChE; IC50 = 110 ± 0.05 µg mL−1). The extract E-G6-32 was subjected to spectroscopic and mass spectrometry analyses. Comparison with the literature data confirmed that (-)-asperpentyn (1) was a major component. Asperpentyn belongs to the epoxyquinone family, which has attractive structural complexity, diverse functional groups, and a broad range of biological activities, including specific enzyme inhibitory activity. Our results suggest that Curvularia sp. G6-32 is a promising source of bioactive secondary metabolites and contains (-)-asperpentyn, which has potential pharmaceutical interest.