Phytotoxic Potential of Secondary Metabolites and Semisynthetic Compounds from Endophytic Fungus Xylaria feejeensis Strain SM3e-1b Isolated from Sapium macrocarpum

Abstract

Bioactivity-directed fractionation of the combined culture medium and mycelium extract of the endophytic fungus Xylaria feejeensis strain SM3e-1b, isolated from Sapium macrocarpum, led to the isolation of three known natural products: (4S,5S,6S)-4-hydroxy-3-methoxy-5-methyl-5,6-epoxycyclohex-2-enone or coriloxine, 1; 2-hydroxy-5-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione, 2; and 2,6-dihydroxy-5-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione or fumiquinone B, 3. This is the first report of compound 3 being isolated from this species. Additionally, four new derivatives of coriloxine were prepared: (4R,5S,6R)-6-chloro-4,5-dihydroxy-3-methoxy-5-methylcyclohex-2-enone, 4; 6-hydroxy-5-methyl-3-(methylamino)cyclohexa-2,5- diene-1,4-dione, 5; (4R,5R,6R)-4,5-dihydroxy-3-methoxy-5-methyl-6-(phenylamino)cyclohex-2-enone, 6; and 2-((4-butylphenyl)amino)-5-methoxy-3-methylcyclohexa-2,5-diene-1,4-dione, 7. X-ray analysis allowed us to unambiguously determine the structures and absolute configuration of semisynthetic derivatives 4, 5, and 6. The phytotoxic activity of the three isolated natural products and the coriloxine derivatives is reported. Germination of the seed, root growth, and oxygen uptake of the seedlings of Trifolium pratense, Medicago sativa, Panicum miliaceum, and Amaranthus hypochondriacus were significantly inhibited by all of the tested compounds. In general, they were more effective inhibiting root elongation than suppressing the germination and seedling oxygen uptake processes as shown by their IC50 values.

Insights in Fungal Bioprospecting in Mexico

“…16). All compounds showed a phytotoxic effect in a concentration-dependent manner on germination, elongation of the root, and oxygen uptake (respiration) of seedlings from Trifolium pratense L., Medicago sativa L., A. hypochondriacus, and Panicum miliaceum L. In general, the IC 50 values for all these activities ranged between 0.1-1.1 mM, which were comparable to the values obtained for the commercial herbicides Rival and ExterPro [83]. Of all the compounds, only 17a and 17d inhibited ATP synthesis, basal and uncoupled electron transport, and enhanced the phosphorylating electron transport and Mg 2+ -ATPase enzymatic activity when tested in a series of photosynthetic light reactions in freshly lysed spinach chloroplasts.…”

“…From symptomless healthy leaves of the tree S. macrocarpum, the strain X. feejeensis SM3e-1b was isolated [83]. Bioassay-guided fractionation of the extracts from the culture medium and mycelium led to the isolation of coriloxine (17) and two quinone derivatives, 18 and fumiquinone B (97).…”

Secondary metabolites produced by endophytic fungi: novel antifungal activity of fumiquinone B

“…Fr. (García-Mendez, Macías-Ruvalcaba, Lappe-Oliveiras, Hernández-Ortega, & Macías-Rubalcava, 2016), and is known for its nematicidal activity against Bursaphelenchus xylophilus Steiner & Buhrer, 1934(Hayashi et al, 2007 and for its phytotoxic properties (García-Mendez et al, 2016).…”

Tonantzitlolone A and other cytotoxic constituents of Sapium macrocarpum (Euphorbiaceae)

“…It is used in Mayan traditional medicine to cure skin infections, and particularly, for treating warts [16]. It has not been chemically analyzed previously, but some phytotoxic compounds have been isolated from an endophytic fungus of this species [17]. Here we report the chemical constituents isolated from an extract of the aerial parts of S. macrocarpum, which displayed cytotoxicity in selected tumor cell lines.…”