Planta Med 2020; 86(13/14): 1032-1042
DOI: 10.1055/a-1212-2930
Biological and Pharmacological Activity
Original Papers

Natural Polyketides Isolated from the Endophytic Fungus Phomopsis sp. CAM212 with a Semisynthetic Derivative Downregulating the ERK/IκBα Signaling Pathways

Jean-Bosco Jouda
1   Department of Chemical Engineering, School of Chemical Engineering and Mineral Industries, University of Ngaoundere, Ngaoundere, Cameroon
,
Emmanuel Mfotie Njoya
2   Center for Natural Products Research, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
3   Department of Biochemistry, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
,
Serge Alain Tanemossu Fobofou
4   Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Halle (Saale), Germany
5   Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, USA
,
Zong Yuan Zhou
2   Center for Natural Products Research, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
,
Zhe Qiang
2   Center for Natural Products Research, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
,
Céline Djama Mbazoa
6   Department of Organic Chemistry, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
,
Wolfgang Brandt
4   Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Halle (Saale), Germany
,
Guo-lin Zhang
2   Center for Natural Products Research, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
,
Jean Wandji
6   Department of Organic Chemistry, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
,
Fei Wang
2   Center for Natural Products Research, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
› Author Affiliations
Supported by: National Natural Science Foundation of China 21861142007
Supported by: Bundesministerium für Bildung und Forschung 100318210
Supported by: Deutscher Akademischer Austauschdienst 57316173
Supported by: Deutscher Akademischer Austauschdienst 573169155
Supported by: Deutscher Akademischer Austauschdienst A/12/90548
Supported by: Chinese Academy of Sciences President’s International Fellowship Initiative 2015PB049
Supported by: Biological Resource Network of Chinese Academy of Sciences ZSTH-030
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Abstract

Three previously undescribed natural products, phomopsinin A – C (1 – 3), together with three known compounds, namely, cis-hydroxymellein (4), phomoxanthone A (5) and cytochalasin L-696,474 (6), were isolated from the solid culture of Phomopsis sp. CAM212, an endophytic fungus obtained from Garcinia xanthochymus. Their structures were determined on the basis of spectroscopic data, including IR, NMR, and MS. The absolute configurations of 1 and 2 were assigned by comparing their experimental and calculated ECD spectra. Acetylation of compound 1 yielded 1a, a new natural product derivative that was tested together with other isolated compounds on lipopolysaccharide-stimulated RAW 264.7 cells. Cytochalasin L-696,474 (6) was found to significantly inhibit nitric oxide production, but was highly cytotoxic to the treated cells, whereas compound 1 slightly inhibited nitric oxide production, which was not significantly different compared to lipopolysaccharide-treated cells. Remarkably, the acetylated derivative of 1, compound 1a, significantly inhibited nitric oxide production with an IC50 value of 14.8 µM and no cytotoxic effect on treated cells, thereby showing the importance of the acetyl group in the anti-inflammatory activity of 1a. The study of the mechanism of action revealed that 1a decreases the expression of inducible nitric oxide synthase, cyclooxygenase 2, and proinflammatory cytokine IL-6 without an effect on IL-1β expression. Moreover, it was found that 1a exerts its anti-inflammatory activity in lipopolysaccharide-stimulated RAW 264.7 macrophage cells by downregulating the activation of ERK1/2 and by preventing the translocation of nuclear factor κB. Thus, derivatives of phomopsinin A (1), such as compound 1a, could provide new anti-inflammatory leads.

Supporting Information



Publication History

Received: 29 November 2019

Accepted after revision: 02 July 2020

Article published online:
05 August 2020

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