Flavonoid composition, cellular antioxidant activity and (myelo)peroxidase inhibition of a Bryonia alba L. (Cucurbitaceae) leaves extract

Abstract

Objectives The aim of the present study consisted in the isolation of flavonoids from the leaves of Bryonia alba L. and evaluation of their antioxidant activity and inhibition on peroxidase‐catalysed reactions. Methods Flavonoids were isolated by preparative HPLC‐DAD and their structures were elucidated by MS and NMR. Inhibitory effect was tested by the horseradish peroxidase and the myeloperoxidase assays. Cellular antioxidant assays consisted in testing the inhibitory activity on the reactive oxygen species released upon activation of neutrophils freshly isolated ex vivo from equine blood and of human monocytes‐derived macrophages in vitro. Whole organism toxicity was assessed on zebrafish larvae. Key findings Four flavonoids (lutonarin, saponarin, isoorientin and isovitexin) were isolated. The performed assays showed significant antioxidant activity and inhibition for the peroxidase‐catalysed reactions. Absence of cellular and zebrafish toxicity was confirmed. Conclusions Bryonia alba L. leaves are particularly interesting for their flavonoids content and showed significant inhibitory effect on peroxidase‐catalysed oxidation of substrates (Amplex Red and L012), as well as antioxidant/antiradical activity, proving that this species has a medicinal potential. Moreover, the present study highlights the absence of the toxicity of these leaves and offers though a novel perspective on the species, previously known as being toxic.

Flavonoid Analysis and Antioxidant Activities of the Bryonia alba L. Aerial Parts

“…The crude extract obtained was subjected to the analysis of compounds by HPLC coupled with Diode Array Detection (HPLC-DAD) analysis and to evaluation of antioxidant capacity after being dissolved in analytical grade ethanol (Merck, Darmstadt, Germany). Samples that were subjected to cytotoxicity assays were obtained by dissolving crude extracts in dimethyl sulfoxide (DMSO, Merck, Darmstadt, Germany) at a concentration of 10 mg/mL, while for whole organism toxicity test on zebrafish, crude extracts were suspended in the water used for the development of zebrafish larvae (concentration 1 mg/mL) [15].…”

“…Flavonoids were analyzed by a method described by Ielciu et al [15]. Crude extracts dissolved in methanol (1 mg/mL) were filtered through a 0.45 mm membrane and injected into a Hewlett Packard Agilent 1100 system (Agilent, Santa Clara, California, USA), equipped with an Agilent 1100 quaternary pump (Agilent, Santa Clara, California, USA), an Agilent 1100 degaser, and an Agilent 1100 Automatic Liquid Sampler (Agilent, Santa Clara, California, USA ).…”

“…Embryos were observed each day until 72 hpf (hours post fertilization). Twenty-five larvae were treated once daily with 5 mL of each sample concentration, and another 25 were used as control [15,26].…”

“…The present study was performed in the context of similar studies on this species, and other related species belonging to Cucurbitaceae family, that have aimed to reveal the antioxidant potential of some species belonging to this family that are lesser known for their biological activity or economical uses [13,14,15]. At the same time, the aim of this study was to reveal the fact that Bryonia alba lacks toxicity in all its aerial parts, and to prove its promising potential as an antioxidant agent.…”

Interim Management of COVID-19 by Repurposed Homeopathic Medicines

“…13 Potential drug targets that have been identified by science include angiotensin-converting enzyme 2 (ACE-2) receptor and protease inhibitors. 14,15 Homeopathic medicines such as Bryonia alba, 16 Calendula, 17,18 Passiflora incarnata, 19 and Zingiber officinale, 20 are in use for several other maladies. Based on the properties of their source materials, these medicines might prove to be potential inhibitors of ribosome inactivating protein, proteases, and ACE-2, and hence may be worth investigating for the treatment of COVID-19.…”