Diuretic and anti-diuretic activities of fractions of Alismatis rhizoma

Metabolomic application in toxicity evaluation and toxicological biomarker identification of natural product

Natural product plays a vital role in disease prevention and treatment since the appearance of civilization, but the toxicity severely hinders its wide use. In order to avoid toxic effect as far as possible and use natural product safely, more comprehensive understandings of toxicity are urgently required. Since the metabolome represents the physiological or pathological status of organisms, metabolomics-based toxicology is of significance to observe potential injury before toxins have caused physiological or pathological damages. Metabolomics-based toxicology can evaluate toxicity and identify toxicological biomarker of natural product, which is helpful to guide clinical medication and reduce adverse drug reactions. In the past decades, dozens of metabolomic researches have been implemented on toxicity evaluation, toxicological biomarker identification and potential mechanism exploration of nephrotoxicity, hepatotoxicity, cardiotoxicity and central nervous system toxicity induced by pure compounds, extracts and compound prescriptions. In this paper, metabolomic technology, sample preparation, data process and analysis, and metabolomics-based toxicological research of natural product are reviewed, and finally, the potential problems and further perspectives in toxicological metabolomic investigations of natural product are discussed.

The metabolic change of serum lysophosphatidylcholines involved in the lipid lowering effect of triterpenes from Alismatis rhizoma on high-fat diet induced hyperlipidemia mice

ETHNOPHARMACOLOGICAL RELEVANCE

Alismatis rhizoma (AR), a Traditional Chinese Medicine with lipid-regulating properties, is usually used to treat hyperlipidemia. Lysophosphatidylcholines (Lyso PCs) play a crucial role in lipid metabolism disorders. In this study, the triterpene fraction purified from boiling water extract of AR was evaluated for its lipid lowering activity using mice with high-fat diet (HFD) induced hyperlipidemia. The metabolic changes of individual Lyso PCs treated with the triterpene fraction were detected by ultra-high performance liquid chromatography-triple quadrupole-linear ion trap mass spectrometer (UHPLC-QTRAP-MS/MS).

MATERIALS AND METHODS

HFD induced hyperlipidemia mice were administrated with triterpene and non-triterpene fractions at doses of 180, 360 and 720 mg/kg body weight/day for 4 weeks, respectively. Total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and atherogenic Index (AI) in mice serum were measured. The chemical components in the lipid-lowering fraction were characterized by ultra-high performance liquid chromatography-quadrupole time of flight tandem mass spectrometry (UHPLC-QTOF-MS/MS). The changes of Lyso PC in the serum of mice treated with the lipid-lowering fraction were quantified by UHPLC-QTRAP-MS/MS.

RESULTS

A total of 18 alisol derivatives were identified in the triterpene fraction. The hyperlipidemia mice treated with the triterpene fraction showed a significant decrease in serum TC, LDL-C and AI after continuous consumption of HFD for 4 weeks. The results also showed that 27 serum Lyso PCs in mice fed with HFD were down-regulated, and 19 were up-regulated. The abnormal serum level of Lyso PCs associated with hyperlipidemia was intervened by the alisol derivatives, with increase of unsaturated Lyso PCs and decrease of saturated ones.

CONCLUSIONS

The study demonstrated for the first time that triterpenes from the AR extract can lower serum lipid level in HFD induced hyperlipidemia mice. These metabolism changes of Lyso PCs could further improve our understanding of the potential mechanism of lipid lowering effect of AR.

Characterization and function of the 3-hydroxy-3-methylglutaryl-CoA reductase gene in Alisma orientale (Sam.) Juz. and its relationship with protostane triterpene production

Protostane triterpenes from Alisma orientale (Sam.) Juz. have exhibited distinct pharmacological properties that are currently in high demand. 3-Hydroxy-3-methylglutaryl-CoA reductase (HMGR) is considered the first rate-limiting enzyme in isoprenoid biosynthesis via the mevalonic acid (MVA) pathway. In this study, we cloned a full-length cDNA of A. orientale (Sam.) Juz. HMGR (AoHMGR; 2252 bp; GenBank accession no. KP342318) with an open reading frame (ORF) of 1809 bp. The deduced protein sequence contained four conserved motifs and exhibited homology with HMGR proteins from other plants. We next expressed the cloned gene in Escherichia coli BL21 (Rosetta) cells, collected the expressed products, and incubated those with 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) to determine enzymatic activity. GC/MS analysis revealed that the products were able to catalyze HMG-CoA and NADPH to form MVA. The purified protein was used to immunize New Zealand rabbits and prepare an antibody against AoHMGR. Western blot results demonstrated that the antibodies specifically recognized AoHMGR protein in A. orientale (Sam.) Juz. We then established a rapid test to detect AoHMGR protein in the plant, and found the tuber to be the most AoHMGR protein-abundant organ in A. orientale (Sam.) Juz. Furthermore, we detected the expression level of AoHMGR and contents of the main active component, Alisol B 23-acetate, at different growth phases of A. orientale (Sam.) Juz. A significant positive correlation was identified, indicating that AoHMGR represents a key enzyme in the synthetic pathway of protostane triterpenes.

Traditional uses, phytochemistry, pharmacology, toxicology and quality control of Alisma orientale (Sam.) Juzep: a review

ETHNOPHARMACOLOGICAL RELEVANCE

Rhizoma alismatis (simplified as RA, "Zexie" in Chinese, ) is a well-known natural medicine with long history in Chinese medicine. As a traditional medicine in China, RA is an important part of many prescriptions and has been commonly used for treating a wide range of ailments related to dysuria, edema, nephropathy, hyperlipidaemia, diabetes, inflammation as well as tumor in clinical applications. Based on scientific literatures, the present paper aims to provide comprehensive and up-to date information about the traditional uses, phytochemistry, pharmacology, toxicology and quality control of RA as well as critical analysis of the research. The review will provide a new foundation and direction for the further studies of RA.

MATERIALS AND METHODS

All available information about RA was supplied by library database and electronic search (ScienceDirect, Web of Science, Pubmed, Google Scholar, etc.). The different types of useful information were collected and arranged in corresponding part of the paper.

RESULTS

Phytochemical studies showed that the main chemical composition of RA was the terpenoid including sesquiterpene, diterpene and triterpene. The crude extracts and isolated compounds from RA showed diverse pharmacological activities including diuretic, nephroprotective, anti-hyperlipidemic, anti-atherosclerotic, anti-cancer, anti-inflammatory and anti-oxidative activities. However, high-dose or long-term use of RA can lead to water-electrolyte imbalance, bloody urine, acidosis and even hepatotoxicity or nephrotoxicity, which have been proven by several studies.

CONCLUSIONS

Pharmacological researches show RA possessing various bioactivities including diuresis, nephroprotective effect, anti-hyperlipidemia, etc. However, more bioactive components especially diuretic and nephroprotective compounds need to be isolated and identified, and more rigorous researches on action mechanisms are required. More experiments in vitro or in vivo and clinical studies are encouraged to clarify correlation between traditional uses and modern applications, and the toxicity need to be further and precisely explored. In addition, a standardized fingerprint for RA is indispensable and emergent. These achievements will further expand to therapeutic potential and usage of RA and provide a powerful support for clinical use.