Usnic Acid and Usnea barbata (L.) F.H. Wigg. Dry Extracts Promote Apoptosis and DNA Damage in Human Blood Cells through Enhancing ROS Levels

Abstract

Nowadays, numerous biomedical studies performed on natural compounds and plant extracts aim to obtain highly selective pharmacological activities without unwanted toxic effects. In the big world of medicinal plants, Usnea barbata (L) F.H. Wigg (U. barbata) and usnic acid (UA) are well-known for their therapeutical properties. One of the most studied properties is their cytotoxicity on various tumor cells. This work aims to evaluate their cytotoxic potential on normal blood cells. Three dry U. barbata extracts in various solvents: ethyl acetate (UBEA), acetone (UBA), and ethanol (UBE) were prepared. From UBEA we isolated usnic acid with high purity by semipreparative chromatography. Then, UA, UBA, and UBE dissolved in 1% dimethyl sulfoxide (DMSO) and diluted in four concentrations were tested for their toxicity on human blood cells. The blood samples were collected from a healthy non-smoker donor; the obtained blood cell cultures were treated with the tested samples. After 24 h, the cytotoxic effect was analyzed through the mechanisms that can cause cell death: early and late apoptosis, caspase 3/7 activity, nuclear apoptosis, autophagy, reactive oxygen species (ROS) level and DNA damage. Generally, the cytotoxic effect was directly proportional to the increase of concentrations, usnic acid inducing the most significant response. At high concentrations, usnic acid and U. barbata extracts induced apoptosis and DNA damage in human blood cells, increasing ROS levels. Our study reveals the importance of prior natural products toxicity evaluation on normal cells to anticipate their limits and benefits as potential anticancer drugs.

Antioxidant, Cytotoxic, and Rheological Properties of Canola Oil Extract of Usnea barbata (L.) Weber ex F.H. Wigg from Călimani Mountains, Romania

“…Usnic acid (UA) is a well-known and abundant lichen secondary metabolite and can be isolated from U. barbata [ 14 ] and other Usnea sp. [ 10 ].…”

Evaluation of Usnea barbata (L.) Weber ex F.H. Wigg Extract in Canola Oil Loaded in Bioadhesive Oral Films for Potential Applications in Oral Cavity Infections and Malignancy

“…The blood samples were collected into heparin vacutainers, and the blood cell cultures were obtained according to a previously described method [ 53 ]. Then, the blood cells were treated with F-UBO and controls in Nunclon Vita Cell culture 6-well plates (Kisker Biotech GmbH & Co.KG, Steinfurt, Germany) and incubated in a Steri-Cycle™ i160 CO 2 Incubator (Thermo Fisher Scientific Inc., Waltham, MA, USA), at 37 °C, in 5% CO 2 for 24 h. All flow cytometry analyses were performed after this incubation time.…”

“…The cells with annexin V-FITC and PI (20 µg/mL) were incubated in darkness, for 30 min, at room temperature [ 53 ]. Then, the viable, early apoptotic, late apoptotic, and necrotic cells were examined at a flow cytometer using a 488 nm excitation, green emission for annexin V-FITC (BL1 channel), and orange emission for PI (BL2 channel).…”

UHPLC-MS Metabolomic Fingerprinting, Antioxidant, and Enzyme Inhibition Activities of Himantormia lugubris from Antarctica

“…Popovici et al [32] found in U. barbata variable concentrations of usnic acid in four extracts obtained by different solvents: ethyl acetate (376.73 mg/g), acetone (282.78 mg/g), methanol (137.60 mg/g), and ethanol (127.21 mg/g) [33]. In U. barbata, the usnic acid content present in methanolic extracts [34], ethyl acetate extracts [3], and pure conditions [35] was determined as being responsible for high cytotoxicity on cancer cells, highlighting its potential antitumor activity. Pathak et al [36] found efficient antidermatophytic activity in U. orientalis extract, mediated by the high concentration of usnic acid.…”