Summary of the pharmacological activities of L. platyphylla.
Liriope platyphylla Wang et Tang (L. platyphylla) is named Liriope muscari with Binomial name and called big blue lilyturf, lilyturf, border grass and monkey grass with common name . It is widely used as one of the 50 fundamental herbs in traditional Oriental medicine; the species is one member of low, herbaceous flowing plats, which grows commonly in the shady forests of East Asia including China, Korea and Japan at elevation of 100 to 1400 m. Also, it typically grows 30-45 cm tall and have grass-like evergreen foliage and lilac-purple flowers which produce single seeded berries on spike in the fall [1,2]. Their roots are long fibrous with terminal tubers. Its flower is showy form which an erect spikes with tiered whorls of dense, white to violet-purple flowers rising above the leaves as like grape hyacinth. This flower differents into blackish berries which can maintain their status into winter season (Fig. 1A). Furthermore, L. platyphylla bear a strong likeness to L. spicata (creeping lilyturf) which is the most common species in this genus. Although the prominent flower spike extending above the leaves is alike, the leaves of L. platyphylla were wider and longer than those of L. spicata [3,4].
L. platyphylla is easily well grown in most condition of soil including average, medium, well-drained type in full sun shines to partial shade although the ideal condition for it growth are fertile and moist soils with partial shade. Furthermore, it has a wide range of tolerance for light, heat, humidity, drought and soil condition. Because of these advantages, they widely used as one of the most popular border plant and groundcover in southeastern USA .
Of several parts in L. platyphylla, only roots have generally been used for a variety of purposes, including as a therapeutic drug and in teas (Fig. 1B and C) . However, there are a few studies which purified and elucidated constituents in L. platyphylla. Total 13 chemical constituents were isolated from the chloroform fraction and n-BuOH fraction from EtOH extract of L. platyphylla. These constituents included beta-sitosterol-3-O-beta-D-glucopyranosile, palmic acid, ruscogenin, LP-C, LP-D, 25 (S) -ruscogenin 1-O-beta-D-xylopyranoside-3-O-alpha-L-rhamnopyranoside, lupenone, lupeol, ursolic acid, beta-sitosterol, diosgenin, LP-A and LP-B [5,6].
A variety of previous pharmacological studies have suggested that L. platyphylla may exert beneficial biological effects on inflammation, diabetes, neurodigenerative disorder, obesity and atopic dermatitis (Table 1). However, there are no reviews to publish the report for the therapeutic effects of L. platyphylla on the human chronic disease. Therefore, this chapter describes the important results of an experiment using L. platyphylla which may prove valuable in the development of a therapeutic drug for the treatment of human chronic disease.
|Target Disease||Functional effects||References|
|Inflammation||-Inhibition of bacteria activity|
-Inhibition of airway inflammation and hyperresponsiveness
|Diabetes||-Worked as insulin sensitizer|
-Stimulation of insulin secretion
-Relief of diabetes symptom
|Neurodigenerative disorder||-Stimulation of NGF expression and secretion|
-Induction of neurite outgrowth
-Improvement of learning and memory ability
-Induction of neuronal cell survival and neuritic outgrowth
|Obesity||-Prevention of obesity and hypertriglyceridemia|||
|Atopic dermatitis||-Relief of atopic dermatitis|||
2. Therapeutic effects of L. platyphylla on human chronic disease
This main section described experimental results regarding the biological effects of L. platyphylla on five chronic disease including inflammation, diabetes, neurodigenerative disorder, obesity and atopic dermatitis.
2.1. Effects of L. platyphylla on inflammation
L. platyphylla has been long-used for the treatment against asthma and bronchial and lung inflammation. Firstly, the inhibitory activity of recombinant sortase was evaluated in 80 medicinal plants. In order to test these effects, a total 240 medicinal plant fractions were sequentially purified from 80 plants with n-hexane, ethyl acetate and water. As show Table 2, the high inhibition activity was detected in the ethyl acetate fractions of Cocculus trilobus, Fritillaria vertillata, L. platyphylla and Rhus verniciflua. Especially, the greatest activity was observed in the ethyl acetate fractions of Cocculus trilobus .
|Medicinal plants(part of use)||IC50(μg/ml)|
|Achyranthes bidentata (root)||15.48a|
|Benincasa cerifera (seed)||21.57a|
|Cibotium barometz (rhizome)||39.40a|
|Cimicifuga heracleifolia (rhizome)||26.58a|
|Cocculus trilobus (rhizome)||1.52a|
|Coptis chinensis (rhizome)||16.73a|
|Cuscuta austrailia (fruit)||21.12a|
|Ecodia offcinalis (fruit)||13.51a|
|Fritillaria verticillata (tuber)||8.41a|
|Gleditsia japonica (fruit)||27.74a|
|Liriope platyphylla (tuber)||7.96a|
|Rhus verniciflua (bark)||3.22a|
|Zanthoxylum bungeanum (fruit)||27.29a|
Furthermore, anti-asthmatic effects of L. platyphylla were investigated in ovalbumin (OVA)-induced airway inflammation and asthma murine model. OVA treatment induced significant accumulation of eosinophils into the airway, but co-administration if L. platyphylla induced the decrease of eosinophils and total lung leukocytes (Fig. 2). Also, the level of several important cytokines such as IL-5, IL-13, IL-4 and IgE concentration in Broncho Alveolar Lavage Fluid (BALF) and serum dramatically decreased in L. platyphylla treated group compare to control group (Fig. 3). Therefore, these experiments suggested that L. platyphylla has anti-inflammation and anti-asthmatic activity through regulating the correlation between Th1/Th2 cytokine imbalance .
2.2. Effects of L. platyphylla on diabetes
2.2.1. Role as insulin sensitizer
The therapeutic effects of L. platyphylla on diabetes have been well studied for short period. Early study on insulin action was firstly reported by Choi et al. . In this study, the extract of L. platyphylla was extracted with 70% methanol for 12 hours. And then, this extracts was further separated by passage through a Diaion HP-20 and silica gel column chromatography a stepwise elution by the gradients of chloroform and methanol (9:1, 6:1, 3:1, 2:1 and 1:1). Of these fractions, the 9:1 fraction induced the increase of glucose uptake 1 ng/mL up to glucose uptake 50 ng/mL insulin in 3T3-L1 adipocytes (Fig. 4). Also, this fraction contained several active compounds including homoisoflavones, methylophiopogonone A, ophiopogonone A, methylophiopogonanone A and ophiopogonanone A. Furthermore, this study showed that the insulin stimulated glucose uptake has been regulated by the increase of glucose transporter (Glut 4) contents in plasma membrane and insulin receptor substrate 1 (IRS1)-PI3 kinase-Akt signalling mechanism (Fig. 5). Particularly, Gluts are a group of membrane protein that facilitate the transport of glucose molecule across a cell membrane. Isoform of Glut was classified by a specific role in glucose metabolism including the expression pattern in tissue, substrate specificity, transport kinetics and expression in different physiological conditions . Until now, 13 members of Gluts have been identified on the basis of sequence similarities . Of these, four Gluts (1-4) were well characterized. Glut-1 highly expressed in erythrocytes and endothelial cells of barrier tissues, and was responsible for the low-level of basal glucose uptake. Glut-2 was widely distributed in renal tubular cells, small intestinal epithelial cells, liver cells and pancreatic beta cells. Especially, in the liver cells, it was required to uptake glucose for glycolysis and release the glucose produced from gluconeogenesis. Most of Glut-3 was expressed in neurons and placenta and Glut-4 was founded in adipose tissue and striated muscle . Therefore, this study suggested possibility that homoisoflavone-enriched fraction of L. platyphylla may have the potential role as an insulin sensitizer .
2.2.2. Role as insulin stimulator in vitro
Recently, a role as insulin stimulator of L. platyphylla is being extensively researched with our group. Ten novel extracts including LP-H, LP-E, LP-M, LP-M80, LP-M50, LP-H20, LP9M80-H, LP9M80-C, LP9M80-B, LP9M80 were newly extracted from L. platyphylla with MeOH, EtOH, BuOH and hexan. The insulin secretion ability of these extracts was measured through the detection of insulin concentration in supernatant of HIT-T15 cells (hamster pancreatic beta cells). Of then extacts, the highest concentration of insulin was detected in LP9M80-H treated group, followed by the LP-H, LP-M, LP-E and LP9M80-C treated group. Furthermore, the optimal concentration of LP9M80-H was determined at approximately 100-125 μg/ml using cell viability test and insulin ELISA in HIT-T15 cells (Fig. 6). This study suggested that novel extracts, LP9M80-H could be considered as potential candidate for enhancement of insulin secretion.
In addition, the new approach such as steaming had applicated to L. platyphylla in order to to increase the level or efficacy of their functional components and to induce chemical transformation of specific components. In our previous study, Red L. platyphylla (RLP) has been manufactured with steaming technique under different steaming time and frequencies. Among these, maximum insulin secretion was induced by RLP steamed for 3 hours with two repeated steps (3 hours steaming and 24 hours air-dried) carried out 9 times (Fig. 7). Also, the expression and phosphorylation levels of most components in insulin receptor signalling pathway were significantly enhanced in INS cells (rat pancreatic beta cells) treated with RLP. Furthermore, a significant alteration of glucose transporter expression was detected in same group. Meanwhile, in the study using streptozotocine-induced diabetic model (Type I), the treatment of RLP for 14 days induced the down-regulation of glucose concentration and upregulation of insulin concentration (Fig. 8). These data showed that steaming processed L. platyphylla may be regared as a potential candidate for a relief and treatment of diabetes.
2.2.3. Role as insulin stimulator in vivo
Early work was performed with aqueous extract of L. platyphylla (AELP). In this study, AELP was administrated into nonobese diabetic (NOD) mice showing type I diabetes with 200 mg/kg body weight for 14 weeks. Glucose concentration was significantly suppressed in NOD mice treated with AELP, while this level was increased in vehicle-treated NOD mice (Fig. 9). Also, AELP treated NOD mice showed higher insulin concentration than control NOD mice, although IL-4 and IFN-γ level was decreased in AELP treated NOD mice (Table 3). Therefore, these results indicated that AELP have a components down-regulating glucose concentration via enhancement insulin concentration.
In addition, the therapeutic effects of LP9M80-H which had insulin secretion ability in HIT-T15 cells  had been investigated in normal animals and diabetic model by our group. Firstly, LP9M80-H was administrated into ICR mice for 4 days to investigate the correlation between Glut biosynthesis and the insulin signalling pathway activated by LP9M80-H. The ICR mice treated with LP9M80-H showed lower glucose concentration and higher insulin concentration than vehicle-treated group, although their body weight was remained constant over 5 days (Fig. 10). Also, the expression of Glut-3 was significantly down-regulated through p38 MAP kinase signalling pathway in liver, while the expression of Glut-1 was upregulated by Akt and PI3-K pathway in liver and brain of LP9M80-H treated mice (Fig. 11). Thus, these study showed the first evidences that LP9M80-H could regulate Glut-1 and Glut-3 biosynthesis through the Akt and p38 MAPK signalling pathway in ICR mice.
Furthermore, the effects of LP9M80-H were also investigated in OLEFT rats showing type II diabetes to determine whether or not the therapeutic effects on the pathology of diabetes and obesity. After the oral administration for 2 week, the abdominal fat mass were significantly lower in LP9M80-H treated group than vehicle treated group, although there are no difference in body weight between two group. Also, a significant alteration on glucose and insulin concentration was detected in LP9M80-H treated OLETF rats compare with vehicle treated rats (Fig. 12). Furthermore, LP9M80-H treated OLETF rats showed the decrease of lipid and adiponectin concentration as well as the enhanced expression of insulin receptor and insulin receptor substrate. Especially, the Glut-2 and Glut-3 expression was decreased whereas Glut-4 expression increased by LP9M80-H in liver tissue of OLETF rats (Fig. 13). Therefore, this paper showed that LP9M80-H may also relief the symptoms of diabetes and obesity in Type II model.
2.3. Effects of L. platyphylla on neurodegenerative disorder
2.3.1. Induction effects of Nerve Growth Factor (NGF) secretion in vitro
NGF was one of neurotrophic factors that regulated the neuronal development and maintenance within central nervous system (CNS) and peripheral nervous system (PNS). Many perivous studies showed that NGF could reduce the cholinergic neuronal damage induced from surgical injury  and prove the cognitive ability of aged rodents . Therefore, NGF was considered as a therapeutic drug for the treatment of neurodegenerative disorder such as Alzheimer’s disease and cerebrovascular dementia [25,26].
Firstly, the effects of butanol extract isolated from L. platyphylla (BELP) were investigated in undifferentiated PC12 cells (pheochromocytoma of the rat adrenal medulla) using conditional medium of C6 and primary astrocytes . In order to collect conditional medium, C6 and primary astrocytes were incubated with BELP during 24 hr and then media harvested from these cells. In these results, the neuritic outgrowths of PC12 cells were significantly induced with dose-dependent manner. The maximum length of neurite-bearing cells was observed at a concentration of 10 μg/ml of BELP conditional medium (Fig. 14). Furthermore, the expression and secretion of NGF was determined in C6 cells and primary astrocytes. The NGF concentration was higher in the culture media of BELP-treated C6 and primary astrocytes than these of control. The RT-PCR results showed that BELP treatment induced the increase of the expression level of NGF mRNA (Fig. 15). Therefore, these results suggested that BELP may induce the enhancement of the expression and secretion of NGF in astrocytes.
Meanwhile, Hur et al  studied the effects of spicatoside A on NGF secretion and NGF receptor signalling pathway. Spicatoside A used in this study was isolated from dried tubers of L. platyphylla using bioactivityguided isolation techniques and their structure was determined with 1H NMR and 13C NMR analysis (Varian U1500, 500 MHz, CD3OD)(Fig. 16). Then, their effects on neurite outgrowth in undifferentiated PC12 cells were investigated. The neuritic outgrowth was significantly increased in PC12 cells treated with spicatoside A and their effects observed at 10 μg/ml were very similar to that of NGF at 50 ng/ml (Fig. 17). In most of animal cells, Trk, a high affinity NGF receptor regulated the cell survival and neuritic outgrowth via ERK1/2 and PI3-kinase signaling pathway . Therefore, the effects of spicatoside A on NGF receptor and their downstream signaling pathway in undifferentiated PC12 cells were examined using western blot analysis to investigate NGF ability. The high level of TrkA phosphorylation was detected in the spicatoside A-treated PC12 cells (Fig. 18). Also, spicatoside A-treated PC12 cells showed the increase level of ERK1/2 and Akt phosphorylation level compare with control group (Fig. 18). In conclusion, spicatoside A may induce the neuritic outgrowth of PC12 cells through TrkA signaling pathway including ERK1/2 and PI3-kinase pathway.
2.3.2. Induction effects of NGF secretion in vivo
The NGF stimulation effects of L. platyphylla observed in several cell lines was further investigated base on behavioural and physiological features in mice. Firstly, the effects of ethanol (70%) extract of roots of L. platyphylla (EELP) on learning and memory was measured in ICR mice using the passive avoidance task. The sub-chronic treatment of four different concentrations of EELP induced a significant group effect on the step-through latency in retention trial. Especially, these latencies were significantly loger in EELP-treated group than those in vehicle-treated group (Fig. 19). In addition, EELP effect on the BDNF and NGF expression was detected in brain of ICR mice using immunohistochemistry. BDNF immunoreative cells were dramatically increased in CA1 region of hippocampus and dentate gyrus region in a dose dependent manner. Furthermore, NGF immunostaining cells were increased by treatment of EELP in dentate gyrus region of ICR mice, while those cells did not detected in CA1 region of hippocampus (Fig. 20). Above results showed that EELP administration could improve the learning and memory of mice through the increase of BDNF and NGF expression.
Meanwhile, Nam et al.  reported the 100% methanol extracts isolated from L. platyphylla (MELP) on NGF metabolism. Firstly, they collected a total 13 novel extract from the roots of L. platyphylla using various solvent such as ethylacetate, methanol, hexan, butanol and chloroform. Of these extracts, only four extracts (LP-E, LP-M, LP-M50 and LP2E17P) induced the NGF secretion and mRNA expression in neuroblastoma cells, although the NGF-induced neuritic outgrowth from PC12 cells was only induced by LP-E, LP-M and LP-M50 (Fig. 21). Furthermore, in vivo effect of LP-M was investigated in C57BL/6 mice treated with 50 mg/kg of LP-M for 2 weeks. The expression level of NGF mRNA was significantly increased in LP-M treated mice compare with vehicle treated goup. The signaling pathway of TrkA NGF receptor was dramatically activated in hippocampus of mice via LP-M treatment, while the signaling pathway of p75NTR was inhibited in the cortex by LP-M treatment (Fig. 22). Then, these results suggested the possibility that four novel extracts of L. platyphylla was considered to be a good candidate for a neurodegenerative disease-therapeutic drug.
2.4. Therapeutic effects on other diseases
2.4.1. Prevent effects on obesity
Obesity was caused by an energy imbalance induced by an increase ration of caloric intake to energy expenditure. Recently, a development of novel drug for obesity has received attention as important topics. In an effort of develop drug for the treatment of obesity, Hur et al.  investigated the therapeutic effects of Gyeongshingangjeehwan which composed of four medicinal plants, L. platyphylla, P. grandiflorum, S chinensis, and E. sinica using OLEFT rats. Firstly, abdominal fat area was significantly decreased by 12.1% in GGEx (X5) treated OLETF rats and 42.8% in GGEx (X10) group (Fig. 23A and B). Compare with the LETO group, the leptin level that reflects changes in body weight and adipose tissue mass  were 172% higher in the vehicle treated OLETF rats. But, GGEx treatment decreased leptin levels by 23.5% in vehicle treated OLETF rats with similar level to those in sibutramine (oral anorexiant)-treated obese rats (Fig. 23C). Also, the beneficial effects of GGEx on circulating lipid profile including triglyceride and total cholesterol were examined. GGEx treated OLETF rats showed a reduction of plasma triglycerides by 28.7% although total cholesterol level were unaffected by GGEx treatment (Fig. 24). Furthermore, the hepatic lipid accumulation were markedly lower in GGEx treated OLETF rats than those in vehicle treated OLETF rats (Fig. 25), while the mRNA level of PPARα target enzymes were upregulated by GGEx administration . These results suggest that GGEx including L. platyphylla may effectively prevent obesity and hypertriglyceridemia through the inhibition of feeding and the activation of hepatic PPAR.
2.4.2. Therapeutic effects on atopic dermatitis
Atopic dermatitis was a typical skin disorder showing inflammatory, chronically relapsing, noncontagious and pruritic symptoms. Also, they were induced by several factors such as epidermal barrier dysfunction, allergy, microwave radiation, food allergy, histamine intolerance and other biological factors. Recently, Kim et al.  has investigated the effects of aqueous extracts of L. platyphylla (AELP) on atopic dermatitis of NC/Nga mice after phthalic anhydride (PA) treatment. In this animal model, 10% AELP treated mice showed the significant decline of the pathological phenotypes of atopic dermatitis such as erythema, ear thickness, edema, scab and discharge compare to control group (Fig. 26). Also, the weight of immune related organs including lymph node and thymus were gradually decreased in AELP treated groups, while the weight of spleen was slightly increased in same group (Fig. 27). The significant histological changes including inflammation, edema, epidermal hyperplasia were observed in 5% and 10% AELP treated group. Furthermore, toluidine blue staining analysis, a method used to specifically identify the mast cell, showed that the decrease of master cell infiltration into the dermis were statistically observed in 5% AELP and 10% AELP treated groups (Fig. 28). The IgE concentration was lower in only 10% AELP treated group than that in control group although this level was not affected in 5% AELP treated group. Therefore, these results indicated that the aqueous extracts of L. platyphylla may contribute the relieve of atopic dermatitis symptoms.
The development and identification of novel therapeutic drugs for human chronic disease was considered as a very important project in the field of pharmacological and clinical research. Among the variety of approaches thus far pursued to develop novel drugs, identification and screening of natural compounds from medicinal herbs has proven a very effective one—not least, because this method saves a great deal of time and cost. Recently, some scientists including our group in Asia countries have reported the therapeutic effects of L. platyphylla on the human chronic disease. This chapter introduces some extracts and compound which may prove valuable in efforts to combat chronic diseases such as inflammation, neurodegenerative disorders, diabetes, obesity and atopic dermatitis.
Three extracts prepared with n-hexane, ethyl acetate and water was found to significantly induce anti-inflammation and anti-asthmatic effects in model animals. Some extracts of L. platyphylla play a role as insulin sensitizer in adipocytes and stimulator in insulinoma cells and the pancreas of mice. Additionally, butanol extracts and spicatoside A markedly induced NGF secretion and expression in some cell lines, while ethanol and methanol extracts induced in mice. Furthermore, recent studies showed that GGEx and water extracts prevented or improved the obesity and atopic dermatitis.
In conclusion, the results of above studies indicated that some extracts and compounds from L. platyphylla could contribute the relief and prevent of several chronic diseases including dementia, diabetes, obesity and atopic dermatitis. However, more research was needed to verify the action mechanism and toxicity side effects.