Cytotoxic Constituents of the Bark of Hypericum roeperianum towards Multidrug-Resistant Cancer Cells

Michel-Gael F Guefack; Francois Damen; Armelle T Mbaveng; Simplice Beaudelaire Tankeo; Gabin T M Bitchagno; İlhami Çelik; James D Simo Mpetga; Victor Kuete

doi:10.1155/2020/4314807

Cytotoxic Constituents of the Bark of Hypericum roeperianum towards Multidrug-Resistant Cancer Cells

Evid Based Complement Alternat Med. 2020 Sep 25:2020:4314807. doi: 10.1155/2020/4314807. eCollection 2020.

Authors

Michel-Gael F Guefack¹, Francois Damen², Armelle T Mbaveng¹, Simplice Beaudelaire Tankeo¹, Gabin T M Bitchagno², İlhami Çelik³, James D Simo Mpetga², Victor Kuete¹

Affiliations

¹ Department of Biochemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon.
² Department of Chemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon.
³ Department of Chemistry, Faculty of Science, Eskisehir Technical University, Eskisehir 26470, Turkey.

Abstract

The global cancer burden remains a serious concern with the alarming incidence of one in eight men and one in eleven women dying in developing countries. This situation is aggravated by the multidrug resistance (MDR) of cancer cells that hampers chemotherapy. In this study, the cytotoxicity of the methanol extract (HRB), fractions (HRBa, HRBb, and HRBa1-5), and compounds from the bark of Hypericum roeperianum (HRB) was evaluated towards a panel of 9 cancer cell lines. The mode of action of the HRB and trichadonic acid (1) was also studied. Column chromatography was applied to isolate the constituents of HRB. The cytotoxicity of botanicals and phytochemicals was evaluated by the resazurin reduction assay (RRA). Caspase-Glo assay was used to evaluate the activity of caspases, and reactive oxygen species (ROS) (H₂DCFH-DA) were assessed by flow cytometry. Phytochemicals isolated from HRB were trichadonic acid (1), fridelan-3-one (2), 2-hydroxy-5-methoxyxanthone (3), norathyriol (4), 1,3,5,6-tetrahydroxyxanthone (5), betulinic acid (6), 3'-hydroxymethyl-2'-(4″-hydroxy-3″,5″-dimethoxyphenyl)-5',6':5,6-(6,8-dihydroxyxanthone)-1',4'-dioxane (7), and 3'-hydroxymethyl-2'-(4″-hydroxy-3″,5″-dimethoxyphenyl)-5',6':5,6-(xanthone)-1',4'-dioxane (8). Botanicals HRB, HRBa, HRBa2-4, HRBb, and doxorubicin displayed cytotoxic effects towards the 9 tested cancer cell lines. The recorded IC₅₀ values ranged from 11.43 µg/mL (against the P-glycoprotein (gp)-overexpressing CEM/ADR5000 leukemia cells) to 26.75 µg/mL (against HCT116 (p53^+/+) colon adenocarcinoma cells) for the crude extract HRB. Compounds 1, 5, and doxorubicin displayed cytotoxic effects towards the 9 tested cancer cell lines with IC₅₀ values varying from 14.44 µM (against CCRF-CEM leukemia cells) to 44.20 µM (against the resistant HCT116 (p53^-/-) cells) for 1 and from 38.46 µM (against CEM/ADR5000 cells) to 112.27 µM (against the resistant HCT116 (p53^-/-) cells) for 5. HRB and compound 1 induced apoptosis in CCRF-CEM cells. The apoptotic process was mediated by enhanced ROS production for HRB or via caspases activation and enhanced ROS production for compound 1. This study demonstrated that Hypericum roeperianum is a potential source of cytotoxic phytochemicals such as trichadonic acid and could be further exploited in cancer chemotherapy.