Antioxidant, antitumoral, antimetastatic effect and inhibition of collagenase enzyme activity of Eleutherine bulbosa (Dayak onion) extract: In vitro, in vivo and in silico approaches

Eleutherine bulbosa (Mill.) Urb., known in Brazil as “marupazinho”, is a medicinal plant native to the Amazon region. The bulbs of this species are traditionally used in the form of tea or consumed in natura (salads) for the treatment of hypertension, diabetes, gastrointestinal problems, breast cancer, and female fertility. It has been reported that this species possess cytotoxic compounds with anticancer action and limited underlying mechanisms. This study aimed to analyze extract of E. bulbosa bulbs and evaluate antioxidant activity, antitumor and antimetastatic effects against murine B16F10-Nex2 melanoma cells, and collagenase inhibitory activity by in vitro, in vivo, and in silico approaches. Determination of total polyphenols, flavonoids and anthocyanins content were performed. In addition, high performance liquid chromatography-mass spectrometry (HPLC-MS) was carried out to identify phytoconstituents from extract. Antioxidant evaluation was performed using DPPH radical scavenging, ferric ion reducing antioxidant power (FRAP), Thiobarbituric acid reactive species (TBARS) and nitric oxide (NO) tests. Antitumoral and antimetastatic activities of extract on murine B16F10-Nex2 melanoma cells were determined and inhibitory activity on collagenase was evaluated. Molecular interactions between compounds and DNA or collagenase was evaluated by molecular docking analyses. Phytochemical evaluation demonstrated the presence of polyphenols, flavonoids and anthocyanins, and HPLC-MS identified the major presence of eleutherin, isoeleutherin and eleutherinol. Antioxidant evaluation showed that the extract present significant activity in all methods evaluated. In silico assay demonstrated interaction between bioactive compounds and DNA or collagenase. In addition, extract exhibited antitumor and antimetastatic actions promoted by melanoma cells and showed collagenase inhibitory activity. The results showed that E. bulbosa bulb extract contains bioactive compounds as flavonoids, anthocyanins and quinones of which may be responsible for the antioxidant, antitumor, antimetastatic and collagenase enzyme inhibitory activity observed in this study by in vivo, in vitro and in silico bioassays.