Two new compounds, deacetylisowortmins A and B, isolated from an endophytic Fungus, Talaromyces wortmannii LGT-4

Abstract Two new compounds, deacetylisowortmins A (1) and B (2), were isolated from Talaromyces wortmannii LGT-4. Their structures were established by 1D and 2D NMR spectra, as well as comparison of the experimental and calculated electronic circular dichroism spectra. Monoamine oxidase and acetylcholinesterase inhibitory activities of 1 and 2 were also evaluated.

Monoamine oxidase inhibitors (MAOIs) are used clinically as antidepressants, anxiolytics, and they can also be used for improving the symptoms associated with Parkinson's disease and Alzheimer's disease (AD) (Lühr et al. 2010). Acetylcholinesterase inhibitors (AChEIs) are the most effective drugs for the treatment of AD (Munoz-Torrero et al. 2006). However, some side-effects have been found when using the current MAOIs and AChEIs. So, searching for new MAOIs and AChEIs still draws much attention. In recent years, we have been focusing on the research on isolation and identification of new MAOIs and AChEIs from plants and their endophytes and have found some potent MAOIs and AChEIs (Yang et al. 2012;Lai et al. 2013;Zhi et al. 2014). In order to get more MAOIs and AChEIs, we tested the activities of 1 and 2. unfortunately, they didn't exhibit potent activities.

General experimental procedures
NMR spectra were obtained on a Bruker Avance-3 spectrometer at 600 MHz. HRESI-MS were measured on a Delta Plus spectrometer. Optical rotations were measured by a JASCO P-1030 polarimeter. IR spectra were recorded on a Perkin Elmer 1600 FT IR spectrophotometer as KBr pellets and the absorption frequencies were expressed in reciprocal centimeters (cm −1 ). ECD spectra were obtained on a DSM1000 spectrometer. HPLC purifications were performed using a Waters HPLC apparatus with two 510 pumps and one 2487 dual λ absorbance detector. Silica gel (200-400 mesh) were from Qingdao Marine Chemical Co., Ltd. China. Macroporous resins (HPD-100) were purchased from Zhengzhou Qinshi Technology Co., Ltd., China.

Fermentation
The fungus grown on the PDA medium was transferred to six 500 mL Erlenmeyer flasks containing 80 g of rice and 100 mL of water (after having been autoclaved) under sterile condition. Cultures were kept for 30 days at 28 °C under static condition.

ECD calculation
The geometries of the molecules were first optimized by Gaussian 09 package (Frisch, et al. Gaussian 09, Revision A.1. Gaussian, Inc. Wallingford CT) at B3LYP/6-31G (d,p) computational level. The output structures were then saved as input structures to conduct ECD calculations using time-dependent density functional theory with B3LYP functional and DGDZVP basis set. All circular dichroism calculations were performed by considering the solvation effect using polarizable continuum model and the methanol was specified as the solvent, which was in agreement with the experiment condition.

Monoamine oxidase assay
The procedure of testing Monoamine oxidase (MAO) inhibiting activity was the same with that reported in our previous paper (Zhi et al. 2014).

Acetylcholinesterase assay
The procedure of testing AChE inhibiting activity was the same with that reported in our previous paper (Yang et al. 2012).

Disclosure statement
No potential conflict of interest was reported by the authors.