Research Progress of Rhodobryum roseum Limpr.

Jinru LI, Yanqing XIE, Wenhong TAN, Hao SUN, Lu LIU*

1. Yunnan University of Chinese Medicine, Kunming 650500, China; 2. China Resources Modern Chinese Medicine (Kunming) Co., Ltd., Kunming 652200, China

Abstract This paper systematically expounds the chemical composition, pharmacological activity and clinical application of Rhodobryum roseum Limpr., in order to provide a reference for further research and development.

Key words Rhodobryum roseum Limpr., Chemical constituents, Pharmacological action, Clinical application

1 Introduction

RhodobryumroseumLimpr. is a plant in the Bryaceae family, and its whole grass can be used in medicine. It is distributed in wet woodland, gully slope and other places. According to the records of the literature[1-5], this medicine has a bitter taste, neutral nature, and has the effects of calming the mind and nourishing the heart, clearing the liver and improving vision. It is mainly used to treat dizziness, palpitation, neurasthenia and other diseases. Ethnic minorities such as Yi, Jingpo and Lisu use it to treat cardiovascular diseases[6-7]. In addition, according to the records in theDictionaryofTraditionalChineseMedicine[1], bryophytes are the only non-poisonous plants in the plant kingdom. In this paper, the research ofR.roseumLimpr. in recent years is reviewed in order to provide a reference for further research and development.

2 Chemical constituents

2.1 FlavonoidsThe flavonoids inR.roseumLimpr. are apigenin, quercetin and other compounds. Zhou Weidongetal.[8]used ultrasonic extraction method to extract the total flavonoids, and the yield of total flavonoids was 0.250%. Li Chaoetal.[9]extracted total flavonoids fromR.roseumLimpr. with 60% ethanol solution, and the extraction rate was 0.166%. Dai Changetal.[10-11]isolated and identified apigenin (1) and quercetin (2) from ethyl acetate and ethyl acetate of 95% ethanol extract fromR.roseumLimpr., and Jiao Weietal.[12]isolated and identified quercetin fromR.giganteum(Hook.) Par. The structure is shown in Fig.1A.

2.2 TerpenesR.roseumLimpr. mainly contains pentacyclic triterpenoids. Jiao Weietal.[12]isolated ursolic acid (3) for the first time fromR.giganteum(Hook.) Par. in Sichuan. Li Bole[13]isolated and identified a new compound (Dehydrovomifoliol) (4) from 95% ethanol extract ofR.roseumLimpr. by high performance liquid chromatography (HPLC), high speed countercurrent chromatography (HSCCC) and gas chromatography-mass spectrometry (GC-MS). Some new terpenoids were isolated and identified: oleanolic acid (5)[10-12], 2α-hydroxyoleanolic acid (6)[10-12], 2α-ursolic acid (7)[10-12], friedelin (8)[10-12]and so on. Friedelinol (9) and 3β-hydroxy-ole-an-9(11)-ene (10) were isolated for the first time by Zhang Haijuan[14]. Wang Bo[15-16]etal.identified ursolic acid (3) from ethyl acetate and ethyl acetate of 95% ethanol extract fromR.roseumLimpr., and some researchers isolated diterpenoid glycosides stevioside (12)[11]. The structure is shown in Fig.1B.

2.3 SteroidsSome new steroids were also isolated: β-sitosterol (12)[12], daucosterol (13)[12], Ergosta-7, 22-d-ien-3β, 5α, 6β-ol (14)[12]. Zhang Qihanetal.[17]isolated and identified 5, 22-Cholestadien-24β-methyl-3β-ol (15), 24α-Met-hyl-5-cholesten-3β-ol (16) and stigmasterol (17) from bryophytes. Wang Boetal.[18]isolated and identified 5, 8-epidioxy-5α, 8α-ergosta-6, 22E-dien-3β-ol (18)[14, 18], 3β-hydroxy-5α, 8α-epidioxygosta-6, 9 (11), 22-triene (19)[14, 18], daucosterol (13)[18], Diphenoethene (20). The structure is shown in Fig.1C.

Fig.1 Structural formula of flavonoids (A), terpenoids (B) and steroids (C) in Rhodobryum roseum Limpr.

2.4 Phenolic acidsThere are a large number of phenolic acids inR.roseumLimpr. At present, protocatechuic acid (21)[10-11], P-hydroxybenzoic acid (22)[10-11], P-hydroxycinna-mic-acid (23)[10-11]and caffeic acid (24)[11]were isolated and identified. In addition, new compounds have been found: caffeic acid methyl ester (25)[18], methyl piperate (26)[18], 4-hydroxy-3, 5-dimethoxybenzoic acid (27)[14], 4-hydroxy-3-methoxy-benzoic acid (28)[14], 4-hydroxy-3, 5-di-met-hoxy-benza-ldehyde (29)[14], 1-(4-hydroxy-3, 5-dimethoxyphen-yl)ethanone (30)[14], 3, 3’, 5, 5’-tetramethoxy-(1, 1’-biphenyl)-4, 4’-diol (31)[14], 4-hydroxy-3-methoxybenzaldehyde (32)[14], and 4-h-y-droxybenzaldehyde (33)[14]. The structure is shown in Fig.2 (A).

2.5 Fatty acidsFatty acid compounds were isolated fromR.giganteum(Hook.) Par. in Sichuan for the first time: succinic acid (34)[11, 12, 16], (E)-4-ethoxy-4-oxobut-2-enoic acid (35)[14], 5-ethoxy-5-oxo-pentanoic acid (36)[14], 4-oxohexanoic acid (37)[14], (E)-4-hydrox-yhe-x-2-enoic acid (38)[14], tetracosanoic acid (39)[14], palmic acid (40)[11], N-hexacosanoic acid (41)[11], N-octacosanoic acid (42)[11], N-triacontanoic acid (43)[11], and Adipic acid (44)[11]. The structure is shown in Fig.2B.

Fig.2 Structural formula of cymbal oxalic acid (A) and fatty acid (B) in Rhodobryum roseum Limpr.

2.6 AlkaloidsAlkaloids were found inR.giganteum(Hook.) Par. andR.roseumLimpr. for the first time: uracil (45)[12], piperate, including 3 stereoisomers (46, 47, 48)[18], uridine (49)[18], and allantoin (50)[11]. The structure is shown in Fig.3A.

Fig.3 Structural formula of alkaloids (A) and other compounds (B) in Rhodobryum roseum Limpr.

2.7 Volatile oilsThe volatile oil inR.roseumLimpr. is composed of fatty acids, alcohols, ester aldehydes, unsaturated alkanes and terpenes. But it is mainly dominated by organic acids. Qiao Feietal.[19]used distillation method to extract volatile oil fromR.giganteum(Hook.) Par., and 21 compounds were identified by CC-MS, accounting for 85.17% of the total volatile oil. Jiao Weietal.[20]used steam distillation method to extract volatile oil fromR.roseumLimpr. in Sichuan, and 52 volatile oil compounds were identified by gas chromatography-mass spectrometry (GC-MS), accounting for 85.67% of the total volatile oil. The chemical composition of the volatile oil is shown in Table 1.

Table 1 Volatile oil compounds in Rhodobryum roseum Limpr.

2.8 Other compoundsSome researchers also isolated alkanes fromR.roseumLimpr.: Tritriacontane (51)[17], nonacosane (52)[12]; cumarins: 3-hydroxy-2-methyl-4H-pyran-4-one (53)[14]; sugars：fructose (54)[12], 3, 5, 3’, 5’-tetramethoxy-4, 4’-diphenol (55)[16]. The structure is shown in Fig.3B.

3 Pharmacological effects of R. roseum Limpr.

R.roseumLimpr. has rich biological activity, such as calming the liver and strengthening heart, anti-inflammation, clearing heat and diuresis, and its good pharmacological activity is worthy of further study.

3.1 Lowering blood pressureAfter usingR.roseumLimpr. water extract and Huixinkang as medicine to the duodenum of ligated rats, Lei Xiulingetal.[21-22]found that both of them could significantly reduce the blood pressure of rats, and the blood pressure was more stable and lasted longer compared with many commonly used antihypertensive drugs. Lei Xiulingetal.[23-24]established the model of myocardial ischemia induced by ligation of coronary artery in rats, and found thatR.roseumLimpr. could decrease LDH, CPK and MDA, and significantly increase SOD. The results showed thatR.roseumLimpr. had a certain protective effect on myocardial ischemia in rats.

3.2 Anti-myocardial ischemia and anti-myocardial hypoxia

Dai Changetal.[11]studied the effect ofR.roseumLimpr. on cardiomyocytes with ethyl acetate and its monomer components(oleanolic acid, 2α-hydroxyoleanolic acid, 2α-hydroxyursulic acid, apigenin, quercetin and caffeic acid). The results showed that the active part of ethyl acetate was significantly superior to the monomer components, andR.roseumLimpr. had protective effect against myocardial ischemia. Xie Tingtingetal.[25]studied the effects of different extract parts ofR.roseumLimpr. on acute myocardial ischemia in rats, and results showed that 50% ethanol extract could prevent experimental myocardial ischemia. Xu Jianminetal.[26]established a rat model of acute myocardial ischemia. The results showed that the descending shift of S-T segment was alleviated and the levels of serum GOT and LDH were decreased, indicating thatR.roseumLimpr. had a good protective effect on acute myocardial ischemia. Wang Boetal.[18]usedR.roseumLimpr. water extract, 50% alcohol extract and 95% alcohol extract to study the effect on anti-myocardial ischemia in experimental animals. The results showed that methyl piperate and piperine had obvious cardiomyocyte protective effect[27]. Through the Langendorff isolated heart ischemia-reperfusion model, Wang Dongxiaoetal.[28]found that the components ofR.roseumLimpr. could significantly increase the levels of LVSP, CF and ±dp/dtmax in the ischemic and hypoxic heart, and the parts of piperine and ethyl acetate had significant effects on the ischemic and hypoxic heart, indicating that the ethyl acetate and its monomer components inR.roseumLimpr. had myocardial protective effects.

In decapitation experiment and specific hypoxia model, Yu Tengfeietal.[29]used RR7 inR.roseumLimpr. preparation (mostly aqueous extract) to improve the hypoxia tolerance of animals and prolong the survival time. The results showed thatR.roseumLimpr. had a protective effect against cerebral hypoxia. Hu Yuanetal.[30]extractedR.roseumLimpr. with 95% ethanol, 50% ethanol and water. After oral treatment for 11 d, rats were subcutaneously injected with ISO to induce cardiac necrosis. The results showed that there was significant myocardial necrosis in rats, the consumption of endogenous antioxidants and the serum level of labeled enzymes increased, indicating thatR.roseumLimpr. could protect cardiomyocytes. Cai Yingetal.[31]established the mouse model of acute myocardial hypoxia by using different extracts ofR.giganteum(Hook.) Par. The results showed that p-hydroxycinnamic acid and 7, 8-dihydroxycoumarin had protective effects on myocardial hypoxia-reoxygenation injury. Cai Xiaojunetal.[32]studied the effect of water extract ofR.roseumLimpr. on hypoxic injury of cardiomyocytes, and found that it could protect cardiomyocytes from hypoxia injury. Zhang Haijuan[14]studied the protective effects of aromatic compounds inR.roseumLimpr. on oxidative damage of cardiomyocytes, and found thatR.roseumLimpr. had anti-oxidative effect on myocardial cells. Wang Dongxiaoetal.[33]studied the effects of different parts ofR.roseumLimpr. on myocardial ischemia and hypoxia tolerance. The results showed that both of them could significantly reduce the incidence of ventricular fibrillation, increase hypoxia tolerance in mice under normobaric pressure and prolong the survival time. The survival time of mice with specific myocardial ischemia and hypoxia increased significantly, and the results showed thatR.roseumLimpr. could significantly improve the ability of hypoxia tolerance and anti-myocardial ischemia in mice.

3.3 Reducing blood viscosityYu Yuemingetal.[34]established the model of acute myocardial ischemia and found that the plasma viscosity and whole blood viscosity at each shear rate decreased in the treatment group after the use ofR.roseumLimpr. injection, indicating thatR.roseumLimpr. could activate blood circulation and remove blood stasis and could improve the hyperviscosity syndrome after developing acute myocardial ischemia.

3.4 Having effects on atherosclerosis and blood lipidsYu Yuemingetal.[35]established the rabbit atherosclerosis model by high-fat diet. The treatment group was treated withR.roseumLimpr. on the basis of high-fat diet. The results showed that the indicators of TC, TG, LDL and TC/HDL in the experimental group decreased significantly, and the area of atherosclerotic plaque in the intima decreased significantly, indicating thatR.roseumLimpr. could resist atherosclerosis, reduce blood lipids and improve blood lipid metabolism and have other pharmacological effects. Xiao Jimingetal.[36]studied the effect ofR.roseumLimpr. extract on atherosclerotic plaque and myocardial infarction in rabbits, and found that atherosclerosis and myocardial ischemic necrosis were significantly alleviated. The experiment showed thatR.roseumLimpr. had the effect of anti-atherosclerosis and reducing blood lipid.

3.5 Having effects on hemodynamics and myocardial metabolismLi Ruisongetal.[37-38]injected alcohol dialysate and fat-soluble phenols fromR.roseumLimpr. into the femoral vein of anesthetized dogs with ligation of LAD. The results showed that both of them significantly increased coronary flow in normal area, decreased myocardial oxygen consumption and slightly increased nutritional blood flow in infarcted area.

4 Clinical application

R.roseumLimpr. herb is bitter in taste and neutral in nature. It has the effects of calming the mind, clearing the liver and improving vision, tranquilizing and allaying excitement. It is mainly widely used in the treatment of heart disease in clinic. People often use it alone or use it combined with other kinds of traditional Chinese medicine, which has a good effect on angina pectoris, old myocardial infarction, coronary heart disease and other diseases.

4.1 Treatment of insomniaZhan Pingetal.[39]studied the Yi medicine Huixin Ningshen. The cure rate of this prescription on intractable insomnia reached 88.8%, with good curative effect and no toxic and side effects.R.roseumLimpr. in the prescription had the effect of nourishing the heart and calming the mind, so it is commonly used in Yi medicine.

4.2 Treatment of coronary heart diseaseWang Youhuaetal.[40]divided 60 patients with ischemic heart disease into integrated traditional Chinese and Western medicine treatment group and Western medicine control group, and observed the changes of clinical efficacy, electrocardiogram, DD and vWF before and after treatment. The treatment efficiency was 93.33% in the treatment group and 73.33% in the control group. The results showed thatR.roseumLimpr. was effective in the treatment of ischemic heart disease. Cai Yingetal.[41]studied the effect ofR.roseumLimpr. sugar-free granule on diabetes mellitus complicated with coronary heart disease and angina pectoris, and found thatR.roseumLimpr. sugar-free granule had a good therapeutic effect on patients with diabetes mellitus complicated with coronary heart disease and angina pectoris. The curative effect was similar to that of Shexiang Baoxin Pill. Ying Li[42]collected and analyzed the proved effective prescription and literature of Yunnan ethnic medicine in the treatment of heart disease, and found that Yunnan ethnic minorities, especially Dai, Yi and Tibetan, often use drugs of nourishing the heart and calming the mind, warming yang and tonifying the heart in the treatment of palpitation, chest arthralgia and other diseases. The national medicineR.roseumLimpr. was the most frequently used.

4.3 Treatment of angina pectorisR.roseumLimpr. is often used in folk to treat heart disease. It can be used in combination with jujube, crystal sugar and pig heart to effectively treat angina pectoris. Qiao Yuanguietal.[43]usedR.roseumLimpr. decoction to treat angina pectoris, and the therapeutic efficiency was 87.88%, indicating thatR.roseumLimpr. could treat angina pectoris.

4.4 Treatment of arrhythmiasLi Mingxiaoetal.[44]divided 84 patients (frequent ventricular extrasystole) into two groups. In the treatment group, it was treated withR.roseumLimpr. on the basis of the control group. The results showed that the treatment efficiency of the treatment group was as high as 95.2%, indicating thatR.roseumLimpr. could effectively treat arrhythmia and other diseases.

5 Discussion

R.roseumLimpr. has a good effect in the prevention and treatment of cardiovascular diseases in folk clinical use. In recent years, a large number of pharmacological experiments have fully confirmed thatR.roseumLimpr. has rich pharmacological activity and has played a good role in the treatment of cardiovascular, nervous system diseases, tumor and so on. Ursolic acid in the chemical components ofR.roseumLimpr. can be anti-cancer, anti-bacterial, anti-inflammatory, anti-viral[45]. Caffeic acid has anti-oxidant, anti-viral pharmacological activity, and can protect hepatocytes and enhance immunity[46]. Protocatechuic acid can be anti-inflammatory, anti-viral[47], anti-oxidant, and protect hepatocytes[48]. Quercetin has anti-inflammatory and anticancer effects[49]. A large number of clinical trials and studies have also fully shown thatR.roseumLimpr. has a significant clinical effect.R.roseumLimpr. decoction can treat hypertension, hyperlipidemia, heart disease, insomnia, diabetes and other diseases. The pharmacological effect ofR.roseumLimpr. has made it effective in the clinical treatment.R.roseumLimpr. is widely used among ethnic minorities, but there is little research on its quality standard, and it has not been further updated with the development of research. The research and development of pharmacological activity ofR.roseumLimpr. has a broad medicinal prospect. Its clinical application should be further enhanced with the study of pharmacological activity.