Polysaccharide and ethanol extracts of Anoectochilus formosanus Hayata: Antioxidant, wound-healing, antibacterial, and cytotoxic activities

Introduction: Polysaccharide and alcohol extracts of Anoectochilus formosanus Hayata have attracted great attention as they exhibit noteworthy properties such as prebiotic and antihyperglycemic effects. However, the antioxidant and wound-healing activities of the polysaccharide extract as well as the antibacterial and cytotoxic effects of the ethanol extracts have not been thoroughly uncovered. Therefore, our study investigated these bioactivities of the two extracts prepared from Anoectochilus formosanus to broaden understandings of medical benefits of the plant. Methods: The monosaccharide composition was analyzed by HPAEC-PAD. The antioxidant and wound-healing activities of the polysaccharide extract were evaluated by ABTS and scratch assays, respectively. The broth dilution method was used to determine the antibacterial ability of the ethanol extract. Additionally, the cytotoxic and mechanistic effects of this extract against hepatocellular carcinoma HUH-7 cells was assessed by MTT assay, qRT-PCR and Western blotting methods. Results: The polysaccharide extract possessed an effective free radical scavenging ability in an ABTS assay (IC50 = 44.92 mu g/ml). The extract also ameliorated wound recovery in a fibroblast scratch assay. Meanwhile, the ethanol extract was able to inhibit the growth of Staphylococcus aureus (MIC = 2500 mu g/ml), Bacillus cereus (MIC = 2500 mu g/ml), Escherichia coli (MIC = 2500 mu g/ ml), and Pseudomonas aeruginosa (MIC = 1250 mu g/ml). Additionally, it repressed the viability of HUH-7 cells (IC50 = 53.44 mu g/ml), possibly through upregulating the expression of caspase 3 (CASP3), CASP8, and CASP9 at both mRNA and protein levels. Conclusion: The polysaccharide extract of A. formosanus exhibited the antioxidant and woundhealing properties whereas the ethanol extract showed the antibacterial activity and cytotoxicity against HUH-7 cells. These findings specify notable biological effects of the two extracts which could be of potential use in human healthcare.