Through bioassay-guided fractionation, the EtOAc extract of a culture broth of the endophytic fungus Phoma species ZJWCF006 in Arisaema erubescens afforded a new α-tetralone derivative, (3S)-3,6,7-trihydroxy-α-tetralone (1), together with cercosporamide (2), β-sitosterol (3), and trichodermin (4). The structures of compounds were established on the basis of spectroscopic analyses. Compounds 1, 2, and 3 were obtained from Phoma species for the first time. Additionally, the compounds were subjected to bioactivity assays, including antimicrobial activity, against four plant pathogenic fungi (Fusarium oxysporium, Rhizoctonia solani, Colletotrichum gloeosporioides, and Magnaporthe oryzae) and two plant pathogenic bacteria (Xanthomonas campestris and Xanthomonas oryzae), as well as in vitro antitumor activities against HT-29, SMMC-772, MCF-7, HL-60, MGC80-3, and P388 cell lines. Compound 1 showed growth inhibition against F. oxysporium and R. solani with EC50 values of 413.22 and 48.5 μg/mL, respectively. Additionally, compound 1 showed no cytotoxicity, whereas compound 2 exhibited cytotoxic activity against the six tumor cell lines tested, with IC50 values of 9.3 ± 2.8, 27.87 ± 1.78, 48.79 ± 2.56, 37.57 ± 1.65, 27.83 ± 0.48, and 30.37 ± 0.28 μM, respectively. We conclude that endophytic Phoma are promising sources of natural bioactive and novel metabolites.

Bioactive metabolites from Phoma species, an endophytic fungus from the Chinese medicinal plant Arisaema erubescens

Two new benzo[j]fluoranthene-based secondary metabolites named daldinone C (1) and daldinone D (2), along with two known metabolites, altechromone A and (4S)-5,8-dihydroxy-4-methoxy-α-tetralone, were isolated from the CHCl3/MeOH (1:1) extract of a solid culture of the endophyte Hypoxylon truncatum IFB-18 harbored inside the symptomless stem tissue of Artemisia annua. The structures of the new compounds were elucidated by MS and 1D and 2D NMR spectra and by X-ray diffraction analysis. Their absolute configurations were determined unambiguously by a combination of their CD data and the established exciton chirality rule. Compounds 1 and 2 were substantially cytotoxic against SW1116 cells, with IC50 values of 49.5 and 41.0 μM, respectively, comparable to that (37.0 μM) of 5-fluorouracil. The biosynthetic pathway for 1 and 2 was postulated with the natural occurrence of benzo[j]fluoranthene analogues discussed in brief.

Cytotoxic benzo[j]fluoranthene metabolites from Hypoxylon truncatum IFB-18, an endophyte of Artemisia annua.

Regiolone and Isosclerone, Two Enantiomeric Phytotoxic Naphthalenone Pentaketides: Computational Assignment of Absolute Configuration and Its Relationship with Phytotoxic Activity

Secondary metabolites from the roots of Engelhardia roxburghiana and their antitubercular activities.

Twenty-seven naphthoquinones and their derivatives, including four new naphthalenyl glucosides and twenty-three known compounds, were isolated from green walnut husks, which came from Juglans mandshurica Maxim. The structures of four new naphthalenyl glucosides were elucidated based on extensive spectroscopic analyses. All of these compounds were evaluated for their cytotoxic activities against the growth of human cancer cells lines HepG-2 by MTT [3-(4,5-dimethylthiazo l-2-yl)-2,5 diphenyl tetrazolium bromide] assay. The results were shown that most naphthoquinones in an aglycone form exhibited better cytotoxicity in vitro than naphthalenyl glucosides with IC50 values in the range of 7.33-88.23 μM. Meanwhile, preliminary structure-activity relationships for these compounds were discussed.

https://www.mdpi.com/1420-3049/20/9/15572/pdf

Studies on Cytotoxic Activity against HepG-2 Cells of Naphthoquinones from Green Walnut Husks of Juglans mandshurica Maxim

Four enantiomerically pure new α-tetralones, (4S)- and (4R)-5-hydroxy-4-methoxy-α-tetralones and (4S)- and (4R)-5,8-dihydroxy-4-methoxy-α-tetralones were isolated, together with five known ones, (4S)- and (4R)-4,8-dihydroxy-α-tetralones, (4S)-4,8-dihydroxy-5-methoxy-α-tetralone and (4S)- and (4R)-4-hydroxy-α-tetralones, from the fruit of Juglans mandshurica MAXIM. var. sieboldiana MAKINO. Their structures were established on the basis of spectral analysis. To the best of our knowledge, this is the first isolation of the (4R)-4-hydroxy-α-tetralone derivative from Juglans species.

Studies on the Constituents of Juglans Species. I. Structural Determination of (4S)- and (4R)-4-Hydroxy-α-tetralone Derivatives from the Fruit of Juglans mandshurica M AXIM. var. sieboldiana M AKINO

Takayuki Kasahara

Papers

Studies on the Constituents of Juglans Species. I. Structural Determination of (4S)- and (4R)-4-Hydroxy-α-tetralone Derivatives from the Fruit of Juglans mandshurica M AXIM. var. sieboldiana M AKINO