Depsidones and a dihydroxanthenone from the endophytic fungi Simplicillium lanosoniveum (J.F.H. Beyma) Zare & W. Gams PSU-H168 and PSU-H261.

Three new compounds including two depsidones (simplicildones J and K) and one dihydroxanthenone (globosuxanthone E) together with nine known compounds were obtained from the crude extracts of two endophytic fungi Simplicillium lanosoniveum (J.F.H. Beyma) Zare & W. Gams PSU-H168 and PSU-H261 which were isolated from the leaves of Hevea brasiliensis. The structures were elucidated by spectroscopic evidence. The absolute configuration of globosuxanthone E was established by means of experimental and calculated TDDFT ECD data. Simplicildone K exhibited antibacterial activity against Staphylococcus aureus and methicillin-resistant S. aureus with equal MIC values of 128 µg/mL. Simplicildone K and globosuxanthone E displayed antifungal activity against Cryptococcus neoformans ATCC90113 with the same MIC values of 32 µg/mL. In addition, known botryohordine C and simplicildone A showed phosphodiesterase 5 inhibitory activity with the IC50 values of 5.69 and 9.96 µM, respectively, and were noncytotoxic toward noncancerous Vero cells.

Salicylic Acid Induces Resistance in Rubber Tree against Phytophthora palmivora.

Induced resistance by elicitors is considered to be an eco-friendly strategy to stimulate plant defense against pathogen attack. In this study, we elucidated the effect of salicylic acid (SA) on induced resistance in rubber tree against Phytophthora palmivora and evaluated the possible defense mechanisms that were involved. For SA pretreatment, rubber tree exhibited a significant reduction in disease severity by 41%. Consistent with the occurrence of induced resistance, the pronounced increase in H2O2 level, catalase (CAT) and peroxidase (POD) activities were observed. For defense reactions, exogenous SA promoted the increases of H2O2, CAT, POD and phenylalanine ammonia lyase (PAL) activities, including lignin, endogenous SA and scopoletin (Scp) contents. However, SA had different effects on the activity of each CAT isoform in the particular rubber tree organs. Besides, three partial cDNAs encoding CAT (HbCAT1, HbCAT2 and HbCAT3) and a partial cDNA encoding PAL (HbPAL) were isolated from rubber tree. Moreover, the expressions of HbCAT1, HbPAL and HbPR1 were induced by SA. Our findings suggested that, upon SA priming, the elevated H2O2, CAT, POD and PAL activities, lignin, endogenous SA and Scp contents, including the up-regulated HbCAT1, HbPAL and HbPR1 expressions could potentiate the resistance in rubber tree against P. palmivora.