Guava (Syzygium aqueum), a typical Indonesian crop plant, has diuretic properties. Plants used as diuretic medicines can also be valuable sources for endophytic fungi containing diuretic drugs. The aims of this study were to isolate and identify endophytic fungi from S. aqueum stems, to isolate their secondary metabolites, and to conduct in vivo tests of the diuretic activity of an endophytic fungus extract on white male rats of the Wistar strain. Endophytic fungi were isolated by a direct plating method, and fungal isolates were identified molecularly. A phenolic compound was isolated by chromatography, and the chemical structure was identified spectroscopically. Doses of 100, 200, and 300 mg/kg BW were administered to white male rats divided into six groups (normal control, negative control, positive control, and the three treatment groups). Diuretic tests included urine volume; sodium, chloride, and calcium electrolyte levels; and pH. Phylogenetic analysis identified the endophytic fungal isolate as Trichoderma ghanense (isolation code SA1). The secondary metabolite isolated from the T. ghanense extract was a phenolic compound. Diuretic tests using the endophytic fungus extract showed the highest urine volume with a dose of 300 mg/kg BW. The diuretic test results showed an increase in urine volume and levels of sodium, potassium, and chloride ions in the urine. The extract of T. ghanense isolated from the stem of S. aqueum has the potential as initial therapy for hypertension because it contains phenolic secondary metabolites that show diuretic activity.
Secondary metabolites from the endophytic fungus Pestalotiopsis virgatula isolated from the mangrove plant Sonneratia caseolaris
