A new p-terphenyl derivative from the insect-derived fungus Aspergillus candidus Bdf-2 and the synergistic effects of terphenyllin

Tijiang Shan; Yuyang Wang; Song Wang; Yunying Xie; Zehua Cui; Chunyin Wu; Jian Sun; Jun Wang; Ziling Mao

doi:10.7717/peerj.8221

A new p-terphenyl derivative from the insect-derived fungus Aspergillus candidus Bdf-2 and the synergistic effects of terphenyllin

PeerJ. 2020 Jan 2:8:e8221. doi: 10.7717/peerj.8221. eCollection 2020.

Authors

Tijiang Shan^#¹, Yuyang Wang^#¹, Song Wang¹, Yunying Xie², Zehua Cui³, Chunyin Wu¹, Jian Sun³, Jun Wang¹, Ziling Mao¹

Affiliations

¹ Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, Guangdong, China.
² Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peaking Union Medical College, Beijing, China.
³ National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, Guangdong, China.

^# Contributed equally.

Abstract

A new p-terphenyl derivative 4″-deoxy-2'-methoxyterphenyllin (1), along with six known p-terphenyl derivatives (2-7), a known flavonoid derivative dechlorochlorflavonin (8) and a known fellutanine A (9), were isolated from the insect-derived strain of the fungus Aspergillus candidus Bdf-2, associated with Blaptica dubia. The structure of 1 was established by the analysis of the 1D and 2D NMR and HR-ESI-MS spectra. Compounds 1-9 were evaluated for antibacterial activities against Staphylococcus aureus ATCC29213, Escherichia coli ATCC25922 and Ralstonia solanacearum, and for antioxidant activities. Synergistic effects of compound 2 with the other compounds were also investigated. As a result, compound 6 displayed the best antibacterial activities in all single compound with MIC value of 32 µg/mL against S. aureus ATCC29213 and R. solanacearum, respectively. However, no antibacterial effect against E. coli ATCC25922 was detected from any single compound. The combination of 2 + 6 exhibited obvious synergistic effect against S. aureus ATCC29213 and the MIC value was 4 µg/mL. Compound 6 also showed the best antioxidant activity as a single compound with an IC₅₀ value of 17.62 µg/mL. Combinations of 5 + 6, 2 + 4 + 5 and 2 + 4 + 5 + 6 displayed synergistic effect and their antioxidant activities were better than that of any single compound.

Keywords: Aspergillus candidus Bdf-2; Insect-derived fungus; Secondary metabolites; Structure elucidation; Synergistic effects; p-terphenyl derivatives.

Grants and funding

This work was supported by the Province Natural Science Foundation of Guangdong (No. 2017A030313200), the National Natural Science Foundation of China (No. 31400544), the Distinguish Young Scientist Starting Grant of Guangdong Province (No. 2017KQNCX016) and the Innovation and Entrepreneurship Training Program for College Students of South China Agricultural University (No. 201910564396). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.