Mitigating Effects of Liriope platyphylla on Nicotine-Induced Behavioral Sensitization and Quality Control of Compounds

In this study we investigated the mitigating effects of Liriope platyphylla Wang et Tang extract on behavioral sensitization and the quantification of its major compounds. The extract of L. platyphylla reduces the expression of tyrosine hydroxylase (TH) protein, which is increased by nicotine, back to normal levels, and increases the expression of dopamine transporter (DAT) protein, which is reduced by nicotine, back to normal levels in PC12 cells. In this study, rats received nicotine (0.4 mg/kg, subcutaneously) only for seven days and then received extract of L. platyphylla (200 or 400 mg/kg, oral) 1 h prior to nicotine administration for an additional seven days. The extract of L. platyphylla reduced locomotor activity compared to the nicotine control group in rats. The extract of L. platyphylla significantly attenuated the repeated nicotine-induced DAT protein expression in the nucleus accumbens (NAc), but there was no effect on increased TH protein expression in the dorsal striatum. These findings suggest that L. platyphylla extract has a mitigating effect on nicotine-induced behavioral sensitization by modulating DAT protein expression in the NAc. For quality control of L. plathyphylla, spicatoside A and D, which are saponin compounds, were quantified in the L. platyphylla extract. The amounts of spicatoside A and D in L. platyphylla extract obtained from ultra-high-performance liquid chromatography with tandem mass spectrometry were 0.148 and 0.272 mg/g, respectively. The identification of these compounds in L. platyphylla, which can be used for quality control, provides important information for the development of drugs to treat nicotine dependence.

Metabolic Analysis of Four Cultivars of Liriope platyphylla

Liriope platyphylla (Liliaceae), a medical plant distributed mainly in China, Taiwan, and Korea, has been used traditionally for the treatment of cough, sputum, asthma, and neurodegenerative diseases. The present study involved the metabolic profiling of this plant and reports spicatoside A accumulation in four different varieties of L. platyphylla (Cheongyangjaerae, Seongsoo, Cheongsim, and Liriope Tuber No. 1) using HPLC and gas chromatography time-of-flight mass spectrometry (GC–TOFMS). A total of 47 metabolites were detected in the different cultivars using GC–TOFMS-based metabolic profiling. The resulting data were subjected to principal component analysis (PCA) for determining the whole experimental variation, and the different cultivars were separated by score plots. Furthermore, hierarchical clustering, Pearson’s correlation, and partial least-squares discriminant analyses (PLS-DA) were subsequently performed to determine significant differences in the various metabolites of the cultivars. The HPLC data revealed that the presence of spicatoside A was detected in all four cultivars, with the amount of spicatoside A varying among them. Among the cultivars, Liriope Tuber No. 1 contained the highest amount of spicatoside A (1.83 ± 0.13 mg/g dry weight), followed by Cheongyangjaerae (1.25 ± 0.01 mg/g dry weight), Cheongsim (1.09 ± 0.04 mg/g dry weight), and Seongsoo (1.01 ± 0.02 mg/g dry weight). The identification of spicatoside A was confirmed by comparing the retention time of the sample with the retention time of the standard. Moreover, the Cheongsim cultivar contained higher levels of phenolic compounds—including vanillic acid, quinic acid, gallic acid, chlorogenic acid, caffeic acid, and benzoic acid—than those of the other two cultivars. On the other hand, the levels of amino acids were higher in the Seongsoo cultivar. Therefore, this study may help breeders produce new varieties with improved nutraceutical and nutritional qualities.

Laxative Effect of Spicatoside A by Cholinergic Regulation of Enteric Nerve in Loperamide-Induced Constipation: ICR Mice Model

Researches on spicatoside A (SpiA)-containing natural products suggest the possibility of SpiA as a potential laxative to alleviate chronic constipation. However, no studies have been conducted with single compound administration of SpiA. To verify the laxative effects and mechanism of action of SpiA on chronic constipation, we investigated alterations in the excretion parameters, histological structure, and cholinergic regulation of the enteric nerve in the colons of Institute of Cancer Research (ICR) mice with loperamide (Lop)-induced constipation after exposure to 20 mg/kg of SpiA. Decrease in the number, weight and water contents of stools in the Lop+Vehicle treated group significantly recovered after SpiA treatment, and alterations in the histological structure and transmission electron microscopy (TEM) images were improved in the Lop+SpiA treated group. Similar recovery effects were observed in the ability for mucin secretion and expression of the membrane water channel gene (aquaporin 8, AQP8). Furthermore, significant improvements were observed in the acetylcholinesterase (AChE) activity and acetylcholine receptors’ (AChRs) downstream signaling pathway after treatment of SpiA. The levels of gastrointestinal (GI) hormones including cholecystokinin (CCK) and gastrin were also remarkably enhanced in the Lop+SpiA treated group as compared to the Lop+Vehicle treated group. The expression of receptor tyrosine kinase (C-kit) and protein gene product 9.5 (PGP9.5) in Cajal and neural cells, as well as the phosphorylation of myosin light chain (MLC) in smooth muscle cells, were recovered after SpiA exposure. Taken together, the results of the present study provide the first strong evidence that SpiA improves chronic constipation through muscarinic cholinergic regulation of the enteric nerve in a Lop-induced constipation ICR mice model.

Effects of the Inhaled Treatment of Liriope Radix on an Asthmatic Mouse Model

As a treatment for allergic asthma, inhaled treatments such as bronchodilators that contain β2-agonists have an immediate effect, which attenuates airway obstructions and decreases airway hypersensitivity. However, bronchodilators only perform on a one off basis, but not consistently. Asthma is defined as a chronic inflammatory disease of the airways accompanying the overproduction of mucus, airway wall remodeling, bronchial hyperreactivity and airway obstruction. Liriope platyphylla radix extract (LPP), a traditional Korean medicine, has been thoroughly studied and found to be an effective anti-inflammatory medicine. Here, we demonstrate that an inhaled treatment of LPP can attenuate airway hyperresponsiveness (AHR) in an ovalbumin-induced asthmatic mouse model, compared to the saline-treated group (p < 0.01). Moreover, LPP decreases inflammatory cytokine levels, such as eotaxin (p < 0.05), IL-5 (p < 0.05), IL-13 (p < 0.001), RANTES (p < 0.01), and TNF-α (p < 0.05) in the bronchoalveolar lavage (BAL) fluid of asthmatic mice. A histopathological study was carried out to determine the effects of LPP inhalation on mice lung tissue. We performed UPLC/ESI-QTOF-MS, LC/MS, and GC/MS analyses to analyze the chemical constituents of LPP, finding that these are ophiopogonin D, spicatoside A, spicatoside B, benzyl alcohol, and 5-hydroxymethylfurfural. This study demonstrates the effect of an inhaled LPP treatment both on airway AHR and on the inflammatory response in an asthmatic mouse model. Hence, LPP holds significant promise as a nasal inhalant for the treatment of asthmatic airway disease.