Anti-inflammatory and antipruritic effects of luteolin from Perilla (P. frutescens L.) leaves

Abstract

Perilla (Perilla frutescens L.) leaves have shown therapeutic efficacy in the treatment of inflammatory disorders, allergies, bronchial asthma, and systemic damage due to free radicals. In the present study we analyzed the active constituents in perilla leaves using high-performance liquid chromatography (HPLC) and isolated luteolin, a polyphenolic flavonoid. We investigated the anti-inflammatory and antipruritic properties of luteolin. Luteolin inhibited the secretion of inflammatory cytokines such as interleukin-1β (IL-1 β) and tumor necrosis factor-α (TNF-α) from human mast cells (HMC-1) stimulated with phorbol myristate acetate plus calcium ionophore A23187 in a dose-dependent manner. Luteolin also significantly reduced the histamine release from rat peritoneal mast cells stimulated by compound 48/80, a potent histamine liberator. Furthermore, the administration of luteolin markedly inhibited the scratching behavior and vascular permeability induced by pruritogens, such as compound 48/80 or serotonin, in ICR mice. These results suggested that luteolin has potential as a therapeutic agent against inflammation and itch-related skin diseases.

Figure 1

The structure of luteolin isolated from perilla (P. frutescens) leaves.

Figure 2

Effect of luteolin on HMC-1 cell viability. Cells (5 × 10⁵) were treated with 1–20 μM luteolin and then incubated at 37 °C for 12 h. Cell viability was determined by MTT assay. Values are means ± standard deviation (SD) of duplicate determinations from three independent experiments.

Figure 3

Inhibitory effect of luteolin on PMA plus A23187-induced TNF-α (A)- and IL-1β (B) production in HMC-1 cells. Cells (5 × 10⁵) were pretreated with 1–20 μM luteolin for 30 min prior to stimulation with or without 25 nM PMA plus 1 μM A23187 and then incubated at 37 °C for 12 h. Cytokine levels were determined by enzyme-linked immunosorbent assay (ELISA). Values are means ± SD of duplicate determinations from three independent experiments. ^# p < 0.001 versus the non-treated control group; * p < 0.05, ** p < 0.05, *** p < 0.01 versu PMA plus A23187 alone group.

Figure 4

Inhibitory effect of luteolin on histamine released from RPMCs activated with compound 48/80. RPMCs (5 × 10⁵/mL) were pre-treated with or without luteolin at the indicated concentrations for 2 h, and then stimulated with or without compound 48/80 (5 μg/mL). Histamine levels in RPMC supernatants were determined by ELISA. Values are means ± SD of three independent experiments. ^# p < 0.001 versus the non-treated control group; * p < 0.05, ** p < 0.05, *** p < 0.01 versus compound 48/80 alone group.

Figure 5

Effect of luteolin on compound 48/80-induced scratching behavior (A) and vascular permeability (B) in mice. Scratching behavior was counted for 60 min after intradermal injection of compound 48/80 (50 μg/site). Luteolin (1–20 mg/kg) was orally administered 1 h before injection of compound 48/80. Values are means ± standard error (SE) (n = 8). ^# p < 0.001 versus the non-treated control group; * p < 0.05, ** p < 0.05, *** p < 0.01 versus compound 48/80 alone group.

Figure 6

Effect of luteolin on serotonin-induced scratching behavior (A) and vascular permeability (B) in ICR mice. Scratching behavior was counted for 60 min after intradermal injection of serotonin (100 μg/site). Luteolin (1–20 mg/kg) was administered orally 1 h before serotonin injection. Values are means ± SE (n = 8). ^# p < 0.001 versus the non-treated control group; * p < 0.05, ** p < 0.05, *** p < 0.01 versus serotonin alone group.