Screening of Sceptridium ternatum for antitussive and antiasthmatic activity and associated mechanisms

Abstract

Objectives Sceptridium ternatum is an expectorant in traditional Chinese medicine and is prescribed for the treatment of asthma. The study aim was to screen Sceptridium ternatum for ingredients with antitussive and antiasthmatic effects and to study their associated mechanisms. Methods Cough in mice was induced using ammonia. Cough latency and the number of coughs within 3 minutes were determined. Airway responsiveness was assessed using ovalbumin as a sensitizer and characteristic asthma indicators were measured. Results Chloroform and ethyl acetate extracts significantly reduced the number of coughs within 3 minutes, tidal volume, and the percentage of eosinophilic granulocytes, lymphocytes and neutrophils. All extracts decreased airway responsiveness in asthmatic mice compared with the untreated group. Petroleum ether, chloroform and n-butanol extracts lowered the Penh values of asthmatic mice. Petroleum ether and ethyl acetate extracts greatly reduced interleukin-4 expression and the interleukin-4/interferon gamma ratio. Compared with the model group, all extracts reduced mRNA expression of the cysteinyl leukotriene receptor-1 (CysLT₁). Conclusions Chloroform extract and ethyl acetate extract displayed obvious antitussive effects and reduced airway inflammation. Thus, these two extracts contain the effective ingredients of Sceptridium ternatum. The active mechanism was ascribed to inhibition of mRNA expression of the CysLT₁ receptor in mice with bronchial asthma.

Keywords: Sceptridium ternatum; acting mechanism; antiasthmatic; antitussive; asthma; effective ingredients.

Figure 1.

The entire plant of Sceptridium ternatum Herba.

Figure 2.

Flow chart of the extraction process for Sceptridium ternatum. PET: petroleum ether; CHCl₃: chloroform; EtOAc: ethyl acetate; n-BuOH: n-butanol.

Figure 3.

Total iron chromatogram (TIC) graphs of Sceptridium ternatum herb extracts. (a) chloroform extracts; (b) petroleum ether extracts; (c) n-butanol extracts; (d) ethyl acetate extracts.

Figure 4.

Enhanced pause (Penh) measurements.

Figure 5.

Effect of different Sceptridium ternatum extracts on cough latency and the number of coughs induced by ammonia in mice ((a) cough incubation period; (b) cough times). Note: compared with the control group, **P < 0.01.

Figure 6.

Effect of different Sceptridium ternatum extracts on Penh (a) and tidal volume (b) values in mice Mch: methacholine chloride; TV: tidal volume.

Figure 7.

Effect of different Sceptridium ternatum extracts on mice plasma levels of interleukin (IL)-4 and interferon gamma (IFN-γ). The cytokines in supernatant were measured using an ELISA kit. Values are expressed as means ± SEMs (n = 10/group). Compared with control group, ^#P < 0.05; compared with model group, *P < 0.05.

Figure 8.

Effect of different Sceptridium ternatum extracts on the percentage of inflammatory cells in broncho-alveolar lavage fluid of asthmatic mice. Values are expressed as means ± SEMs (n = 10/group). Statistical analysis was performed using Student’s t-test. Compared with control group, ^#P < 0.05; compared with model group, *P < 0.05, ^##P < 0.01; compared with model group, **P < 0.01.

Figure 9.

Biopsies showing effect of different Sceptridium ternatum extracts on lung tissue.

Figure 10.

Agarose gel electrophoresis of CysLT₁ and CysLT₂. CysLT: cysteinyl leukotrienes; GAPDH: glyceraldehyde-3-phosphate dehydrogenase.

Figure 11.

The curve of the relation between ΔCt and cDNA logarithmic concentration for CysLT₁ and GAPDH. CysLT: cysteinyl leukotriene; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; ΔCt: Δ cycle threshold.

Figure 12.

Effect of different Sceptridium ternatum extracts on the expression of mRNA in lung tissue of asthmatic mice. Values are expressed as means ± SEMs (n = 10/group). Compared with control group, #P < 0.05; compared with model group, **P < 0.01, *P < 0.05.