Anti-Inflammatory Activity of Pinus koraiensis Cone Bark Extracts Prepared by Micro-Wave Assisted Extraction

Abstract

In this study, we compared the anti-inflammatory activity of Pinus koraiensis cone bark extracts prepared by conventional extraction and microwave-assisted extraction (MAE). Water extracts and 50% ethanol extracts prepared using MAE were applied to RAW 264.7 cell at 5, 10, 25, and 50 μg/mL of concentrations, and tested for cytoxicity. The group treated with 50 μg/mL of 50% ethanol extracts showed toxicity. In order to investigate the inhibition of nitric oxide (NO) production in RAW 264.7 cells, extracts of water and ethanol were treated with 5, 10, and 25 μg/mL concentrations. The inhibitory activity of water and 50% ethanol extracts groups were determined as 40% and 60% at 25 μg/mL concentration, respectively. We found concentration dependent decreases on inducible NO synthase. The inhibitory effect against forming inflammatory cytokines, prostaglandin E₂, tumor necrosis factor-α, interleukin (IL)-6, and IL-1β, was also superior in the 25 μg/mL treated group than the control group. According to these results, the water extracts and 50% ethanol extracts both inhibited inflammatory mediators by reducing the inflammatory response. Therefore, The MAE extracts of P. koraiensis cone bark can be developed as a functional ingredient with anti-inflammatory activity.

Keywords: Pinus koraiensis; anti-inflammation; cone bark; extracts; micro-wave.

Fig. 1

Effect of Pinus koraiensis cone bark water extract (A) and ethanol extract (B) on RAW 264.7 cell viability. Different letters (a–e) above the bars indicate statistically different (P<0.05).

Fig. 2

Inhibition of nitric oxide (NO) production by Pinus koraiensis cone bark water extract (A) and ethanol extract (B) on RAW 264.7 cells. Different letters (a–e) above the bars indicate statistically different (P<0.05).

Fig. 3

Effect of Pinus koraiensis cone bark extracts on inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 protein expression in RAW 264.7. RAW 264.7 cells cultured in serum-free medium for 1 h were treated with 5, 10, or 25 μg/mL of P. koraiensis cone bark extracts for 24 h. iNOS expression was determined using the Western blot analysis. The histograms show the results of densitometric analysis of iNOS protein expression normalized to β-actin. Pinus koraiensis cone bark water extract (A) and ethanol extract (B) on iNOS, and water extract (C) and ethanol extract (D) on COX-2. Different letters (a–e) above the bars indicate statistically different (P<0.05).

Fig. 4

Inhibition rate of extracts from Pinus koraiensis corn bark. RAW 264.7 cells were incubated with various concentration (5, 10, and 25 μg/mL) of Pinus koraiensis extracts for 1 h and then treated with 1 μg/mL of lipopolysaccharide for 24 h. (A) prostaglandin E₂ (PGE₂), (C) tumor necrosis factor (TNF)-α, (E) interleukin (IL)-6, and (G) IL-1β in water extracts, (B) PGE₂, (D) TNF-α, (F) IL-6, and (H) IL-1β in ethanol extracts. Different letters (a–e) above the bars indicate statistically different (P<0.05).