Wound repair and anti-inflammatory potential of Lonicera japonica in excision wound-induced rats

Abstract

Background: Lonicera japonica Thunb. (Caprifoliaceae), a widely used traditional Chinese medicinal plant, is used to treat some infectious diseases and it may have uses as a healthy food and applications in cosmetics and as an ornamental groundcover. The ethanol extract of the flowering aerial parts of L. japonica (LJEE) was investigated for its healing efficiency in a rat excision wound model.

Methods: Excision wounds were inflicted upon three groups of eight rats each. Healing was assessed by the rate of wound contraction in skin wound sites in rats treated with simple ointment base, 10% (w/w) LJEE ointment, or the reference standard drug, 0.2% (w/w) nitrofurazone ointment. The effects of LJEE on the contents of hydroxyproline and hexosamine during healing were estimated. The antimicrobial activity of LJEE against microorganisms was also assessed. The in vivo anti-inflammatory activity of LJEE was investigated to understand the mechanism of wound healing.

Results: LJEE exhibited significant antimicrobial activity against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Candida albicans, and Candida tropicalis. The ointment formulation prepared with 10% (w/w) LJEE exhibited potent wound healing capacity as evidenced by the wound contraction in the excision wound model. The contents of hydroxyproline and hexosamine also correlated with the observed healing pattern. These findings were supported by the histopathological characteristics of healed wound sections, as greater tissue regeneration, more fibroblasts, and angiogenesis were observed in the 10% (w/w) LJEE ointment-treated group. The results also indicated that LJEE possesses potent anti-inflammatory activity, as it enhanced the production of anti-inflammatory cytokines that suppress proinflammatory cytokine production.

Conclusions: The results suggest that the antimicrobial and anti-inflammatory activities of LJEE act synergistically to accelerate wound repair.

Figure 1

HPLC chromatogram of LJEE (280 nm).

Figure 2

Effect of LJEE ointment on the wound area (A) and the percentage of wound contraction (B) in excision wound models on different days after wounding. Values (mean ± SD) were obtained for each group of eight rats. ^aP < 0.05 and ^bP < 0.01 compared to the values of simple ointment-treated rats on the indicated day in each group.

Figure 3

Macroscopic changes in skin wound sites in rats treated with simple ointment base, 10% (w/w) LJEE ointment, or 0.2% (w/w) nitrofurazone ointment on days 1 and 15 after wounding.

Figure 4

Histological examination of healed wound sections stained with H&E. The photomicrographs show healed wound sections isolated from rats treated with simple ointment base, 10% (w/w) LJEE ointment, or 0.2% (w/w) nitrofurazone ointment on day 15 after wounding. The photomicrographs were taken at a magnification of ×200. Abbreviation: bc, blood capillaries; C, collagen fibers; F, fibroblast. The histopathological scores of the healed wounds are presented in Table 3.