## 3 Therapeutic Use
### Antioxidant  
The antioxidant property of lungwort (_Pulmonaria_) can be considered one of the most important properties, as the antioxidant activity may be responsible for the positive outcome in a number of disease conditions such as arthritis, cancer, inflammation, and diabetes. The antioxidant activity of _P. officinalis_ was explored in different studies with various methods. For the first time, the antioxidant potential of the leaf extract of _P. officinalis_, prepared as a tea, was analyzed in a study conducted on different Bulgarian medicinal plants. The ABTS (2,2\({}^{\prime}\)-azinobis (3-ethylbenzothazoline-6-sulfonic acid)) radical decolorization assay [15] was used to determine the antioxidant potential of the extract in water in terms of Trolox-equivalent antioxidant capacity (TEAC). _P. officinalis_ was among the seven species with considerable antioxidant activity (>2 mM) TEAC values [15]. In another study, the antioxidant activity of the extract from the leaves of _P. mollis_ was also identified, along with other medicinal plants, through different in vitro and in vivo methods including 1,1-diphenyl-2-picrylhydrazyl radical (DPPPH*)-scavenging assay, chelating activity, capacity to protect plasmid DNA (against H2O2) and protective capacity against the bacteriostatic and bactericidal effects of H2O2 and menadione [16]. Further, the antioxidant genes (katG and sodA) expression in _Escherichia coli_ MN23 and QC772 was measured as target genes for the treatment. Later, in search of the phytochemicalal important for the antioxidant property of _P. officinalis_ and _P. obscura_, researchers isolated the phytochemical yunnaneic acid B and analyzed its antioxidant activity through different experiments. The antioxidant activity of yunnaneic acid B isolated from _P. officinalis_ was first calculated using DPPH\({}^{\bullet}\) and peroxyntirte (ONOO\({}^{-}\))-scavenging assays and IC\({}_{50}\) was found to be 7.14 and 50.45 \(\upmu\)g/mL, respectively. Further, the antioxidant activity of blood plasma, exposed to (ONOO\({}^{-}\))-induced oxidative stress, was studied in in vitro conditions. The ferric-reducing (Fe\({}^{3+}\) to Fe\({}^{2+}\)) ability of blood plasma (the FRAP assay) was used to calculate the non-enzymatic antioxidant capacity of the blood. The reduction in the non-enzymatic antioxidant capacity of blood plasma due to oxidative stress was partly prevented with the application of yunnaneic acid B at 1-50 \(\upmu\)g/mL concentrations [29]. Later, the antioxidant activity of aqueous and ethanolic extracts from _P. officinalis_ was found to be correlated with the polyphenol and flavone content of the extract. The highest DPPH radical scavenging activity of the ethanolic extract was found to be 75.47% (at 3 mg/mL). The antioxidant activity of extracts was also determined through the reduction potential of the extract to convert Fe\({}^{3+}\) to Fe\({}^{2+}\), which revealed similar results in correlation with the DPPH method [10]. The optimization of extraction methods for the high concentration of biologically active substances (BAS) was carried out for the dry root culture of _P. officinalis_. Parameters such as time, temperature, and concentration of ethanol for extraction were optimized and the antioxidant property of BAS (polyphenols, flavonoids, and proanthocyanidins) were calculated through DPPH and FRAP methods [21]. The antioxidant activity of the DPPH radical method was 86.96, 75.47, and 51.25% for polyphenols, flavonoids, and proanthocyanidins, respectively. In a recent study, after phytochemical profiling, the ONOO\({}^{-}\) scavenging assay was used to identify the antioxidant potential of extract from the aerial part of _P. officinalis_ and _P. obscura_. The antioxidant activities in terms of IC\({}_{50}\) values were found to be 32.66 and 36.71 g/mL for _P. officinalis_ and _P. obscura_, respectively. Further, the biological properties of both plants were studied in human blood plasma under peroxyntirte-induced oxidative stress.