The genus Asarum: A review on phytochemistry, ethnopharmacology, toxicology and pharmacokinetics

ETHNOPHARMACOLOGICAL RELEVANCE

In essentially every quadrant of the globe, many species of genus Asarum are used as a common herbal medicine and appear in many formulas or Kampo. Crude drug from several medicinal plants of genus Asarum (MA) known as Asari Radix et Rhizoma (ARR) has been proven to have the functions of dispelling cold, relieving pain, and reducing phlegm according to Traditional Chinese Medicine (TCM) theory for thousands of years.

AIM OF THE STUDY

This article reviews the ethnopharmacology, phytochemistry, pharmacology, toxicology and metabolic kinetics related research of genus Asarum to evaluate its ethnopharmacology use and future opportunities for research.

MATERIALS AND METHODS

Information on relevant studies of the genus Asarum was gathered via the Internet using Baidu Scholar, Web of Science, Elsevier, ResearchGate, ACS, Pudmed and Chinese National Knowledge Infrastructure (CNKI). Additionally, information was also obtained from some local books, PhD, MS's dissertations and Pharmacopeias.

RESULTS

The genus Asarum has played an important role in herbal treatment. At present, more than 277 compounds have been isolated or identified from genus Asarum. Among them, volatile oil and lignans are the major active constituents and important chemotaxonomic markers. Modern pharmacological studies indicated that genus Asarum and its active compounds possess a wide range of pharmacological effects, especially analgesic, anti-inflammatory, neuroprotective, cardiovascular protection, antitussive, immunosuppressive, anti-tumor, and microbicidal activities.

CONCLUSIONS

Based on this review, therapeutic potential of genus Asarum has been demonstrated with the pharmacological effects on inflammation, CNS, respiratory regulation, cardiovascular diseases, cancer and microbial infection. The available literature showed that the major activities of the genus Asarum can be attributed to the active lignans and essential oils. Further in-depth studies on the aspects of the genus for mechanism of actions, metabolism, pharmacokinetics, toxicology, drug interactions, and clinical trials are still limited, thereby intensive research and assessments should be performed.

In Silico Investigation of Phytoconstituents of Medicinal Herb 'Piper Longum' Against SARS-CoV-2 by Molecular Docking and Molecular Dynamics Analysis

Unavailability of treatment for the SARS-CoV-2 virus has raised concern among the population worldwide. This has led to many attempts to find alternative options to prevent the infection of the disease, including focusing on vaccines and drugs. The use of natural products and herbal extracts can be a better option in beating the virus and boosting up immunity. In the present paper, we have done a systematic in silico study of papain-like protease of COVID-19 virus with the chemical constituents of herbal plant Piper Longum. Screening of the pharmacokinetic properties is done with thirty-two phytoconstituents of Piper Longum which help us in selecting the most active components of the plant. After selection molecular docking is performed with Aristololactam (C17H11NO4), Fargesin (C21H22O6), l-asarinin (C20H18O6), Lignans Machilin F (C20H22O5), Piperundecalidine (C23H29NO3), and Pluviatilol (C20H20O6). Molecular dynamic (MD) is also performed with the inhibitor-receptor complex which suggest significant inhibition and a stable complex of I-Asarinin with PLpro. Docking scores and simulation results suggest that I-Asarinin can act as a potential drug like candidate against COVID-19.

Simultaneous determination of asarinin, β-eudesmol, and wogonin in rats using ultraperformance liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic studies following administration of standards and Gumiganghwal-tang

Asarinin, β-eudesmol, and wogonin have common antiangiogenic activities and have the potential for use in chemotherapy. Besides, they are multivalent substances that are combined in various herbal medicines. The purpose of this study was to develop a method for simultaneous analysis of asarinin, β-eudesmol, and wogonin, which are representative pharmacological components of Asarum heterotropoides, Atractylodes lancea, and Scutellaria baicalensis, respectively, in rat biosamples using ultraperformance liquid chromatography-tandem mass spectrometry. The three components were separated using 5 mm aqueous ammonium acetate containing 0.1% formic acid and acetonitrile as a mobile phase, equipped with a KINETEX core-shell C₁₈ column. The analysis was quantitated on a triple-quadrupole mass-spectrometer employing electrospray ionization, and operated in the multiple reaction monitoring mode. The chromatograms showed high resolution, sensitivity, and selectivity with no interference with plasma, urine, and feces constituents. The developed analytical method satisfied international guidance criteria and could be successfully applied to the pharmacokinetic (PK) studies evaluating oral bioavailability of asarinin, β-eudesmol, and wogonin after oral and intravenous administration and their urinary and fecal excretion ratios after oral administration to rats. Furthermore, the analysis was extended to PK studies following oral administration of Gumiganghwal-tang. This study was the first simultaneous analysis of the aforesaid three constituents in rat plasma, urine, and feces that also determined their PK parameters.

The Relative Content and Distribution of Absorbed Volatile Organic Compounds in Rats Administered Asari Radix et Rhizoma Are Different between Powder- and Decoction-Treated Groups

Asari Radix et Rhizoma (ARR) is an important traditional Chinese medicine. Volatile organic compounds (VOCs) are the main active constituents of ARR. Research on the metabolite profile of VOCs and the difference of absorbed constituents in vivo after an administration of ARR decoction and powder will be helpful to understand the pharmacological activity and safety of ARR. In this study, headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) was applied to profile the VOCs from ARR in rats in vivo. A total of 153 VOCs were tentatively identified; 101 were original constituents of ARR (98 in the powder-treated group and 43 in the decoction-treated group) and 15 were metabolites, and their metabolic reactions were mainly oxidation and reduction, with only two cases of methylation and esterification, and 37 unclassified compounds were identified only in the ARR-treated group. Of the 153 VOCs identified, 131 were reported in rats after oral administration of ARR for the first time, containing 79 original constituents, 15 metabolites, and 37 unclassified compounds. In the powder-treated group, methyleugenol, safrole, 3,5-dimethoxytoluene (3,5-DMT), 2,3,5-trimethoxytoluene (2,3,5-TMT), and 3,4,5-trimethoxytoluene (3,4,5-TMT) were the main absorbed constituents, the relative contents of which were significantly higher compared to the decoction-treated group, especially methyleugenol, safrole, and 3,5-DMT. In the decoction-treated group, 3,4,5-TMT, 2,3,5-TMT, kakuol, and eugenol were the main constituents with a higher content and wider distribution. The results of this study provide a reference for evaluating the efficacy and safety of ARR.

In Vivo Pharmacokinetic Analysis Utilizing Non-Targeted and Targeted Mass Spectrometry and In Vitro Assay against Transient Receptor Potential Channels of Maobushisaishinto and Its Constituent Asiasari Radix

The Japanese traditional medicine maobushisaishinto (MBST) has been prescribed for treating upper respiratory tract infections, such as a common cold. However, its mode of action is poorly understood, especially concerning the MBST constituent Asiasari Radix (AR). In this study, we focused on AR, with an objective of clarifying its bioavailable active ingredients and role within MBST by performing pharmacokinetic and pharmacological studies. Firstly, we performed qualitative non-targeted analysis utilizing high-resolution mass spectrometry to explore the bioavailable ingredients of AR as well as quantitative targeted analysis to reveal plasma concentrations following oral administration of MBST in rats. Secondly, we performed in vitro pharmacological study of bioavailable AR ingredients in addition to other ingredients of MBST to confirm any agonistic activities against transient receptor potential (TRP) channels. As a result, methyl kakuol and other compounds derived from AR were detected in the rat plasma and showed agonistic activity against TRPA1. This study suggests that methyl kakuol as well as other compounds have the potential to be an active ingredient in AR and thus presumably would contribute in part to the effects exerted by MBST.

Gene isolation, heterologous expression, purification and functional confirmation of sesamin synthase from Sesamum indicum L

Members of Cytochromes P450 super family of enzymes catalyse important biochemical reactions in plants. Some of these reactions are so important that they contribute to enormous chemical diversity seen in plants. Many unique secondary metabolites formed by mediation of these enzymes play key role in plant defence and often contribute to maintenance of human health. In oilseed crop Sesamum indicum, the reaction leading to the formation of clinically important sesamin is catalyzed by a unique methylene-di-oxy bridge forming Cytochrome P450 enzyme sesamin synthase. It is encoded by the gene CYP81Q1. In order to elucidate the structure - function relationship of this enzyme and to apply biotechnological tools for enhancing the production of sesamin in the crop, it was intended to clone and express the enzyme in a heterologous system. In this paper we present our results on synthesis of cDNA, cloning, expression and purification of CYP81Q1 from the developing seeds of sesame crop. Following the same procedure we have also cloned a CYP reductase1 (CPR1) gene (CPR1) to facilitate transfer of electron from NADPH to CYP81Q1 enzyme from the same crop. Functional characterization was performed by expressing the recombinant proteins in E. coli (pET28a/BL21-DE3 codon plus) and its activity was evaluated in vitro by HPLC. We demonstrate that purified CYP81Q1 enzyme, on its own, has limited level of activity in the conversion of pinoresinol to sesamin. Its activity gets considerably enhanced in the presence of CPR1.

Neolignans from Red Raspberry ( Rubus idaeus L.) Exhibit Enantioselective Neuroprotective Effects against H2O2-Induced Oxidative Injury in SH-SY5Y Cells

Red raspberry has been well-known for its nutritional purpose. Although this fruit has been reported for its potent antioxidant activity and health-promoting properties, systematic studies responsible for the bioactive constituents were still insufficient. In the current study, three pairs of dihydrobenzofuran-type enantiomeric neolignans (1a/1b-3a/3b), including two new compounds (1b and 2a), were isolated from the fruit of Rubus idaeus. The structures of these enantiomers were determined through spectroscopic methods and quantum mechanical calculations. Biologically, enantiomers 2a and 2b exhibited significant enantioselective protective effects against H₂O₂-induced neurotoxicity at 50 μM (2a, 86.72 ± 1.17%; 2b, 69.70 ± 1.59%). The underlying mechanism study demonstrated that enantiomer 2a is able to attenuate H₂O₂-induced apoptosis, reactive oxygen species (ROS) generation, and mitochondrial dysfunction in SH-SY5Y cells. Overall, these findings provide a valuable foundation for the understanding of neuroprotective activities of red raspberry and further investigation on its potential application values.

Inhibitory Activities of Sesame Seed Extract and its Constituents against β-Secretase

The need for a preventive agent against dementia led us to screen natural plant resources. Among the herbs and spices tested, sesame seed prepared from Sesamum indicum seeds showed potent β-secretase inhibitory activity. The active principles were determined to be sesamin and sesamolin, typical lignans in S. indicum. The IC50 values of sesamin and sesamolin were 257 and 140 μM, respectively. These compounds were investigated in a preliminary absorption experiment. After oral administration, these compounds were detected in an intact form in the brain and serum. These results suggest that consumption of sesame seeds may prevent dementia by sesamin and sesamolin, the constituents in sesame seeds.