Preparative separation of spirobisnaphthalenes from endophytic fungus Berkleasmium sp. Dzf12 by high-speed counter-current chromatography

Total Synthesis and Antifungal Activity of Palmarumycin CP17 and Its Methoxy Analogues

Total synthesis of naturally occurring spirobisnaphthalene palmarumycin CP₁₇ and its methoxy analogues was first achieved through Friedel-Crafts acylation, Wolff-Kishner reduction, intramolecular cyclization, ketalization, benzylic oxidation, and demethylation using the inexpensive and readily available methoxybenzene, 1,2-dimethoxybenzene and 1,4-dimethoxybenzene and 1,8-dihydroxynaphthalene as raw materials. Demethylation with (CH₃)₃SiI at ambient temperature resulted in ring A aromatization and acetal cleavage to give rise to binaphthyl ethers. The antifungal activities of these spirobisnaphthalene derivatives were evaluated, and the results revealed that 5 and 9b exhibit EC₅₀ values of 9.34 µg/mL and 12.35 µg/mL, respectively, against P. piricola.

Preparative Separation of Main Ustilaginoidins from Rice False Smut Balls by High-Speed Counter-Current Chromatography

Ustilaginoidins are bis-naphtho-γ-pyrone mycotoxins isolated from the rice false smut balls (FSBs) infected by the pathogen Villosiclava virens in rice spikelets on panicles. In order to obtain large amounts of pure ustilaginoidins to further evaluate their biological activities and functions, phytotoxicity on rice, security to human and animals as well as to accelerate their applications as pharmaceuticals, preparative high-speed counter-current chromatography (HSCCC) was successfully applied to the isolation and purification of seven bis-naphtho-γ-pyrone mycotoxins, namely ustilaginoidins A (1), G (2), B (3), H (4), I (5), C (6), and J (7) from the ethyl acetate crude extract of rice FSBs. Both 1 and 2 were prepared by HSCCC from the low-polarity fraction of the crude extract using the two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water at the volume ratio of 6.5:3.5:5.0:5.0. Similarly, 3, 4 and 5 were prepared from the medium-polarity fraction using the system at the volume ratio of 4.0:5.0:5.0:6.0, and 6 and 7 were prepared from the higher-polarity fraction using the system at volume ratio of 3.0:5.0:4.0:6.7. A total of 6.2 mg of 1, 5.1 mg of 2, 3.9 mg of 3, 1.2 mg of 4, 5.7 mg of 5, 3.5 mg of 6, and 6.1 mg of 7 with purities of 88%, 82%, 91%, 80%, 92%, 81% and 83%, respectively, were yielded from total 62 mg fraction samples in three independent HSCCC runs. The structures of the purified ustilaginoidins were characterized by means of physicochemical and spectrometric analysis.

Separation and purification of bioactive botrallin and TMC-264 by a combination of HSCCC and semi-preparative HPLC from endophytic fungus Hyalodendriella sp. Ponipodef12

Two dibenzo-α-pyrones, botrallin (1) and TMC-264 (2) were preparatively separated from crude ethyl acetate extract of the endophytic fungus Hyalodendriella sp. Ponipodef12, which was isolated from the hybrid 'Neva' of Populus deltoides Marsh × P. nigra L. using a combination of high-speed counter-current chromatography (HSCCC) and semi-preparative HPLC. Botrallin (1) with 74.73% of purity and TMC-264 (2) with 82.29% of purity were obtained through HSCCC by employing a solvent system containing n-hexane-ethyl acetate-methanol-water at a volume ratio of 1.2:1.0:0.9:1.0. It was the first time for TMC-264 (2) to be isolated from this fungus. TMC-264 (2) showed strong antimicrobial and antinematodal activity, and botrallin (1) exhibited moderate inhibitory activity on acetylcholinesterase.

Antimicrobial and antioxidant activities and effect of 1-hexadecene addition on palmarumycin C2 and C3 yields in liquid culture of endophytic fungus Berkleasmium sp. Dzf12

Two spirobisnaphthalenes, namely palmarumycins C₂ and C₃, were isolated from cultures of the endophytic fungus Berkleasmium sp. Dzf12 after treatment with 1-hexadecene. After addition of 1-hexadecene at 10% to the medium on day 6 of culture, the maximal yields of palmarumycins C₂ and C₃ were obtained as 0.40 g/L and 1.19 g/L, which were 40.00 fold and 59.50 fold higher, respectively, in comparison with those of the control (0.01 g/L and 0.02 g/L). The results indicated that addition of 1-hexadecene can be an effective strategy for enhancing the production of palmarumycins C₂ and C₃ in liquid culture of endophytic fungus Berkleasmium sp. Dzf12. Palmarumycin C₃ exhibited stronger antimicrobial and antioxidant activities than palmarumycin C₂.