Anemia is a common complication of
chemotherapy and may arise due to premature or suicidal death of red blood cells (RBCs). Prevention of RBC death thus lends itself as a promising strategy to counteract
anemia.
Wogonin (WGN; 5,7-dihydroxy-8-methoxyflavone) is a Wnt inhibitor derived from Scutellaria baicalensis plant with potent cytotoxic and antitumor potential. However, the nature of interaction of WGN with human RBCs is unknown. RBCs from healthy participants were exposed to different hemolytic and eryptotic stimuli for 24 or 48 hr at 37°C in the presence and absence of 100 μM WGN.
Calcium overload was induced by 2 μM
ionomycin, hyperosmotic
shock with excessive
sucrose, oxidative stress by 2-phenethyl
isothiocyanate (
PEITC), and metabolic deprivation by exclusion of
glucose.
Hemolysis was estimated from extracellular
hemoglobin,
phosphatidylserine (PS) exposure by
Annexin V-FITC, intracellular
calcium by Fluo4/AM, and oxidative stress by
2',7'-dichlorodihydrofluorescein diacetate (H2
DCFDA). While WGN did not rescue the cells from the hemolytic activity of
ionomycin, it reduced PS externalization by interfering with
calcium influx under both
ionomycin treatment and metabolic exhaustion. WGN also significantly inhibited PS exposure upon hyperosmotic
shock, but the effect was independent of
calcium entry. Moreover, WGN exhibited antihemolytic and anti-eryptotic activities against
PEITC without appreciable reduction in ROS levels. Altogether, WGN prevents
PEITC-induced
hemolysis and suppresses eryptosis due to
calcium accumulation, hyperosmotic
shock, oxidative stress, and metabolic exhaustion. These novel insights may open new avenues into the therapeutic application of WGN for conditions in which
anemia is commonly encountered, most notably
cancer. PRACTICAL APPLICATIONS: The herbal supplement
Sho-Saiko-To (
Xiaochaihu-tang) is commonly prescribed to relieve symptoms of
liver disease.
Flavonoids from the herbal constituents of
Sho-Saiko-To have demonstrated considerable anti-inflammatory,
antioxidant, antimicrobial, antitumor, and immunomodulatory properties. In this work, we identify WGN, a major
flavonoid in
Sho-Saiko-To, as a novel inhibitor of
hemolysis and eryptosis of human erythrocytes. Since inordinate erythrocyte death is a major obstacle in therapeutic drug development, our findings argue for the use of WGN as a natural alternative, either as a primary or an adjuvant drug, for a wide assortment of pathological conditions including
cancer.