ABSTRACT
Today, Hypericum perforatum L. is probably one of the best-characterized medicinal plants, and hyperforin is its best-characterized constituent. Extracts from H. perforatum are widely used as antidepressants; however, less attention has been given to other properties of hyperforin, such as antitumor, fungicidal, antiviral and antibacterial action, or its possible use as a substance with immunomodulation properties. The present study summarizes results that describe the influence of hyperforin as an immunomodulation agent on phagocytosis and the breakdown of Escherichia coli by human polymorphonuclear neutrophils (PMNs). Hyperforin at 1 - 100 μg/mL concentrations was found to have a major influence on phagocytosis and the breakdown of E. coli by PMNs in vitro. A 100 μg/mL solution of hyperforin increased the uptake of non-opsonized E. coli almost 50-fold, and the uptake of IgG-opsonized E. coli more than threefold; on the other hand, the uptake of serum-opsonized bacteria was reduced to approximately 60% of that of the control. Hyperforin seems to bind to both PMNs and E. coli and acts like an opsonin. The elimination of remnants of IgG-opsonized E. coli from the PMNs was stimulated by hyperforin, while the elimination of remnants from non-op-so nized and serum-opsonized material was unaffected by the drug. Hyperforin exhibited clear immunomodulation ability as a phagocytosisstimulating agent. Hyperforin is probably inactive against human immunodeficiency virus (HIV) and most Gram-negative bacteria. However, it can protect acquired immunodeficiency syndrome (AIDS) patients and other immunocompromised patients by its antibacterial activity against Gram-positive bacteria and by enhancement of phagocytosis of Gram-positive and Gram-negative bacteria; some Gram-negative bacteria, such as Neisseria, are sensitive to hyperforin. Hyperforin has the ability to penetrate the blood-brain barrier (BBB) and blood-testis barrier (BTB) and is a valuable antibacterial agent against meningitis and gonorrhea. These properties of hyperforin are important for an antibiotic with immunomodulation activity in the struggle against the growing mortality in AIDS patients as a result of opportunistic bacteria, as recently shown by Bekondi et al. (2006, Int. J. Infect. Dis. 10, 387-395). It could also help to combat primary and opportunistic pathogens associated with meningitis in adults' relation to HIV serostatus.