4
Introduction
Corneal epithelium plays important roles in the maintenance of corneal function
and integrity. Prolonged corneal epithelial defects may cause corneal opacity,
neovascularization, bacterial infection, and visual loss. To prevent such complications,
corneal epithelial wounds must be re-epithelialized as quickly as possible.
Propolis (honeybee glue), a resinous product consisting of sap, bark and bee
excreta, accumulates in bee hives. It is currently used as a health food and for the
treatment of various ailments. Indeed, it has been shown to have a wide range of
biological activities, principally attributable to the presence of flavonoids (major
component; rutin, quercetin, galangin, etc.) (Isla, Nieva Moreno et al. 2001) and caffeic
acid phenethyl ester (CAPE) (Natarajan, Singh et al. 1996). Hence, the putative
therapeutic properties of propolis could be related to its antibacterial (Bankova,
Marcucci et al. 1996; Drago, Mombelli et al. 2000), anti-inflammatory (Mirzoeva and
Calder 1996), antioxidativa (Krol, Czuba et al. 1990; Scheller, Wilczok et al. 1990)
and/or tumoricidal (Matsuno, Jung et al. 1997; Chen, Weng et al. 2004) activities.
In total, at least 200 compounds have been identified in different samples of
propolis, with more than 100 being present in any given sample. These include: fatty
and phenolic acids and esters, substituted phenolic esters, flavonoids (flavones,
flavanones, flavonols, dihydroflavonols, chalcones), terpenes, ß-steroids, aromatic
aldehydes and alcohols, and derivatives of sesquiterpenes, naphthalene and stilbenes
(Bankova, Christov et al. 1995; Tatefuji, Izumi et al. 1996; Marcucci, Ferreres et al.
2000; Velikova, Bankova et al. 2000). Propolis has a variety of botanical origins, and its
chemical composition can also be variable. Baccharis dracunculifolia DC (Asteraceae),
a native plant from Brazil, is the most important botanical source of Brazilian propolis,
known as green propolis because of its color (Park, Alencar et al. 2002; Kumazawa,