Antibiotic Guanacastane Diterpenoids with Two New Skeletons from Psathyrella candolleana Uncovered by Semisolid and Liquid Media.

The culture of Psathyrella candolleana in host Dioscorea opposite medium produced seven new guanacastane diterpenoids, psayamin (1) as an unprecedented 5/7/6/6/6/6/7/5-fused octacyclic spiro scaffold both under liquid and semisolid conditions, psathins A-C (4-6) with a 5/7/6 tricyclic backbone by liquid medium, psathins D-E (7-8) as the same unprecedented skeletons of 5/6/7/6-fused tetracyclic or 6/7/6 tricyclic structures, and psathin F (9) with a 5/7/5/6 tetracyclic backbone by semisolid medium. The structures were elucidated by detailed spectroscopic analyses and those of 1 and 7 were determined by single-crystal X-ray crystallography. The semisolid culture led to four structure types of the guanacastane diterpenoid. Compound 5 showed antifungal activity against phytopathogen Fusarium incarnatum with a minimum inhibitory concentration (MIC) of 8 µg/mL, while compound 4 showed significant antifungal activity against Alternaria sp. with an MIC of 2 µg/mL. Compounds 1 and 8 also showed antifeedant activities against the silkworms with the feeding deterrence indices of 50%, at the concentrations of 50 µg/cm2. Compound 1 showed significant cytotoxicity with IC50 at 10.87 ± 0.24-15.96 ± 0.30 µM and anti-acetylcholinesterase activity with IC50 at 37.3 µM. Also, compound 1 remarkably induced apoptosis of HL-60 at 10, 20 µM in a concentration-dependent manner. The spiral ring of 1 was vital in cytotoxicity and anti-acetylcholinesterase activity. The different media fermented by P. candolleana resulted in the chemical diversity of bioactive guanacastane diterpenoids and potential applications in the agricultural and food functions.

Antifeedant and Antifungal Activities of Metabolites Isolated from the Coculture of Endophytic Fungus Aspergillus tubingensis S1120 with Red Ginseng.

A new globoscinic acid derivative, aspertubin A (1) along with four known compounds, were obtained from the co-culture of Aspergillus tubingensis S1120 with red ginseng. The chemical structures of compounds were characterized by using spectroscopic methods, the calculated and experimental electronic circular dichroism. Panaxytriol (2) from red ginseng, and asperic acid (4) showed significant antifeedant effect with the antifeedant rates of 75 % and 80 % at the concentrations of 50 µg/cm2 . Monomeric carviolin (3) and asperazine (5) displayed weak attractant activity on silkworm. All compounds were assayed for antifungal activities against phytopathogens A. tubingensis, Nigrospora oryzae and Phoma herbarum and the results indicated that autotoxic aspertubin A (1) and panaxytriol (2) possessed selective inhibition against A. tubingensis with MIC values at 8 µg/mL. The co-culture extract showed higher antifeedant and antifungal activities against P. herbarum than those of monoculture of A. tubingensis in ordinary medium. So the medicinal plant and endophyte showed synergistic effect on the plant disease resistance by active compounds from the coculture of A. tubingensis S1120 and red ginseng.

Antifeedant and antiphytopathogenic metabolites from co-culture of endophyte Irpex lacteus, phytopathogen Nigrospora oryzae, and entomopathogen Beauveria bassiana.

Five new tremulane sesquiterpenoids were isolated from co-culture of endophyte Irpex lacteus, phytopathogen Nigrospora oryzae, and entomopathogen Beauveria bassiana. All compounds showed obvious antifeedant activities against silkworm with inhibition percentages of 73-99%, at concentrations of 50 µg/cm2. Compound 11 indicated notable antifeedant activity with inhibition percentage of 93% at concentration of 6.25 µg/cm2 among them. Compounds 2, 3, 4, 8, 9, 15 and 16 indicated anti-fungal activities against I. lacteus with MIC values ≤8 µg/mL, compounds 11, 12, 16-18 showed significant anti-fungal activity against N. oryzae with MICs ≤ 4 µg/mL, and compounds 2, 5, 12 and 18 indicated significant anti-fungal activity against B. bassiana with MICs ≤ 8 µg/mL. In addition, the I. lacteus should unite B. bassiana to inhibit the production of phytotoxins from N. oryzae in the ternary culture.

Paraverrucsins A-F, Antifeedant, and Antiphytopathogenic Polyketides from Rhizospheric Paraphaeosphaeria verruculosa and Induced Bioactivity Enhancement by Coculturing with Host Plant Dendrobium officinale.

Six new polyketides named paraverrucsins A-F (1-6) with oxabicyclic and dioxatricyclic skeletons, together with eight known metabolites (7-14), were discovered and isolated from the fermentation medium of Paraphaeosphaeria verruculosa. Paraverrucsin A-C possessed a novel decarboxylated skeleton compared with that of trichocladinols. Their structures were elucidated by extensive spectral analysis and DP4+ calculations. Paraverrucsins B/C and D/E were isolated as a mixture for the mutarotation occurred at C-2. Paraverrucsins B/C, D/E, F/trichocladinol B, 8, and 9 displayed antifeedant activities against silkworm larvae, with antifeedant index percentages ranging from 62.5 to 93.0%, at a concentration of 50 µg/cm2. Among them, Paraverrucsins B/C and 9 had EC50 values at 13.9 and 18.2 µg/cm2. Most compounds showed antifungal activities against phytopathogenic fungi with minimum inhibitory concentration (MIC) values of 16-64 µg/mL. Coculture of P. verruculosa and host plant Dendrobium officinale leads to the enhancement of antifeedant and antiphytopathogenic activities. Compounds 1, 2/3, 4/5, 6/14 were tested for cytotoxicity against five human carcinoma cell lines, HL-60, A549, MCF-7, SW480, and SMMC-7721, while they exhibited selected cytotoxicity against SW480 with inhibition ratios of 32-38% at a concentration of 40 µM.