Anti-Coronavirus Efficiency and Redox-Modulating Capacity of Polyphenol-Rich Extracts from Traditional Bulgarian Medicinal Plants

Abstract

Background: The use of various herbal therapists as part of traditional medicine in different parts of the world, including Bulgaria, is due to the knowledge accumulated over the centuries by people about their valuable biological activities. In this study, we investigate extracts from widely used Bulgarian medicinal plants for their ability to prevent the coronavirus infection of cells by testing different mechanisms of antiviral protection, their polyphenol content, and redox-modulating capacity. Methods: The influence on the stage of viral adsorption, the inhibition of extracellular virions, and the protective effect on uninfected cells of the plant’s extracts were reported by the end-point dilution method, and virus titer (in Δ lgs) was determined as compared to the untreated controls. The total content of polyphenols and flavonoids was also determined. We tested the antioxidant power of the extracts by their ability to inhibit the generation of superoxide anionic radicals and to scavenge DPPH radicals. We determined their iron-reducing, copper-reducing, and metal-chelating antioxidant powers. Results: Most of the extracts tested suppress the extracellular virions of HCov. They also inhibit the stage of viral adsorption to the host cell to varying degrees and have a protective effect on healthy cells before being subjected to viral invasion. The examined extracts contained significant levels of polyphenols and quercetin-like flavonoids and showed remarkable antioxidant, radical, and redox-modulating effects. Conclusions: All of these 13 extracts from Bulgarian medicinal plants tested can act as antioxidants and antiviral and symptomatic drugs for the management of coronavirus infection.

Novel antioxidant protein target therapy to counter the prevalence and severity of SARS-CoV-2

“…The effects of 13 Bulgarian medicinal plant extracts on the MCR-5 cell line transfected with the human coronavirus 229E strain were studied by Ilieva N. et al. ( 95 ) In their study, plant extracts of T. vulgaris , M. chamomilla , A. sativum , and P. reptans , among others, were portrayed to have prominent anti-coronavirus activity. Most of the plants suppressed extracellular virions and showed potent redox-modulating effects.…”

Chitosan-Stabilized Liposomal Nanocarriers for Medicinal Plant Extracts from the Bulgarian Flora with Anti-coronavirus Activity

“…In recent years, with raising the need for the development of new approaches to address the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the significance of antiviral, antiinflammatory, and antioxidant properties of the botanical products has become an attractive subject of the research focus [15][16][17]. In this regard, special attention deserves the herbs with higher polyphenol content and in particular quercetin-like flavonoids, which combine the mentioned desirable effects against the oxidative stress inflicted by SARS-CoV-2 in the invaded tissues [18].…”

“…In this regard, special attention deserves the herbs with higher polyphenol content and in particular quercetin-like flavonoids, which combine the mentioned desirable effects against the oxidative stress inflicted by SARS-CoV-2 in the invaded tissues [18]. The polyphenols hinder the viral replication and regulate the immune response by preventing the rise of cytokine storm, as well as inhibits the action of free radicals [17].…”

Antioxidant and Anti-Inflammatory Activities of Endemic Plants of the Australian Wet Tropics

“…However, the excessive formation of ROS can cause oxidative stress and disrupt normal physiological processes by damaging the antioxidant defences that protect the cells. Oxidative stress occurs when the body’s biological system cannot detoxify excessively accumulated ROS in cells [ 1 , 2 ]. The most common ROS species in disease states include hypochlorite, hydrogen peroxide, and a range of radical species, including the superoxide anion, singlet oxygen, hydroxyl, hydroperoxyl, peroxy, and alkoxy radicals [ 3 ].…”