Eulophia macrobulbon - an orchid with significant anti-inflammatory and antioxidant effect and anticancerogenic potential exerted by its root extract

Abstract

Background: The Orchidaceae family is one of the largest families of flowering plants. Orchids are widely used for the traditional herbal medicine, acting as aphrodisiac, antisepic, antimicrobial, anti-cancer agent, etc.

Purpose: This study was designed to elucidate the anti-inflammatory, antioxidant and cytotoxic potential of a 50% ethanolic extract of Eulophia macrobulbon roots (EME) in vitro, an orchid growing in Southern Asia. Furthermore, the main active compounds were isolated, and the bioactivity of the single constituents was determined.

Methods: The anti-inflammatory activity of EME and its compounds was evaluated by the secretion of pro- and anti-inflammatory cytokines and by the expression of inducible nitric oxide synthase (iNOS) in a lipopolysaccharide (LPS)-stimulated macrophage model, as determined by an enzyme linked immunosorbent assay (ELISA) and Western blot. Antioxidant activity was assessed using a DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) photometric assay. Cytotoxic effects were determined using a colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-assay.

Results: EME and its compounds significantly reduced the production of the proinflammatory cytokines interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α), the expression of iNOS and subsequently increased the production of the anti-inflammatory cytokine interleukin 10 (IL-10) in LPS-stimulated macrophages. Additionally it could be demonstrated that EME is rich in radical scavengers. Furthermore, EME and its components showed notable cytotoxic effects on the human cervical adenocarcinoma cell line HeLa, the human colorectal adenocarcinoma cell line CaCo-2 and the human breast adenocarcinoma cell line MCF-7. The most active constituents were identified as 4-methoxy-9,10-dihydro-2,7-phenanthrenediol (8), 4-methoxy-2,7-phenanthrenediol (9), 1,5-dimethoxy-2,7-phenanthrenediol (10), 1,5,7-trimethoxy-2,6-phenanthrenediol (11), 1-(4-hydroxybenzyl)-4,8-dimethoxy-2,7-phenanthrenediol (15).

Conclusion: Based on this data, EME provides various beneficial anti-inflammatory, antioxidant and cytotoxic attributes and may be used as herbal remedy in the pharmaceutical or food industries.

Keywords: Anti-inflammatory; Antioxidant; Cyrtopera macrobulbon; Cytotoxic; Eulophia macrobulbon; Orchid.