Inhibitory effects of kaempferol-3-O-rhamnoside on ovalbumin-induced lung inflammation in a mouse model of allergic asthma

The modification of natural flavonoid by glycosylation alters their physicochemical and pharmacokinetic properties, such as increased water solubility and stability, reduced toxicity, and sometimes enhanced or even new pharmacological activities. Kaempferol (KF), a plant flavonoid, and its glycosylated derivative, kaempferol-3-O-rhamnoside (K-3-rh), were evaluated and compared for their anti-inflammatory, anti-oxidant, and anti-asthmatic effects in an asthma model mouse. The results showed that K-3-rh fully maintained its anti-inflammatory and anti-asthmatic effects compared with KF in an asthma model mouse. Both KF and K-3-rh significantly reduced the elevated inflammatory cell numbers in the bronchoalveolar lavage fluid (BALF). KF and K-3-rh also significantly inhibited the increase in Th2 cytokines (IL-4, IL-5, and IL-13) and TNF-α protein levels through inhibition of the phosphorylation Akt and effectively suppressed eosinophilia in a mouse model of allergic asthma. The total immunoglobulin (Ig) E levels in the serum and BALF were also blocked by KF and K-3-rh to similar extents. K-3-rh exerts similar or even slightly higher inhibitory effects on Th2 cytokines and IgE production compared with KF, whereas K-3-rh was less effective at DPPH radical scavenging and the inhibition of ROS generation in inflammatory cells compared with KF. These results suggested that the K-3-rh, as well as KF, may also be a promising candidate for the development of health beneficial foods or therapeutic agents that can prevent or treat allergic asthma.