Uses, Chemical Composition, and Standardization of Plant Raw Material and Medicinal Substances from Plants of the Genus Asarum L

Complete chloroplast genome of Asarum chungbuensis (C.S. Yook & J.G. Kim) B.U. Oh 2005 (Aristolochiaceae), a Korean endemic species

Asarum chungbuensis, a species endemic to Korea, has a limited distribution across the Korean Peninsula and is used in traditional medicine. Despite its importance, the genome structure, genetic composition, and phylogenetic relationships based on its chloroplast genome have not been documented. In this study, the complete chloroplast genome of A. chungbuensis was newly assembled. The chloroplast genome is 190,179 base pairs (bp) long, and the overall GC content (%) of the plastid was 36.8%. The chloroplast genome size of A. chungbuensis is longer than that of the normal chloroplast genome (160 kb) because of an inverted small single-copy (SSC) duplication that incorporates the SSC into an inverted repeat (IR) region. By extension, this duplication event causes this chloroplast genome to lack an SSC, unlike other formal structures. The chloroplast genome, with a tripartite structure, consisted of a single-copy region of 93,351 bp with a 34.6% GC content and two IR regions, each with a length of 48,414 bp and a 38.8% GC content. Additionally, it was found to have 113 genes, including 79 PCG genes, 30 tRNA genes, and four rRNA genes. Phylogenetic analysis revealed that A. chungbuensis was grouped with A. heterotropoides var. seoulense, which diverged from the clade comprising A. koreanum and A. patens. The newly sequenced A. chungbuensis chloroplast genome could provide valuable genomic information for determining unique genome structures, especially for the assessment of genetic diversity, phylogenetic relationships, species conservation, and biogeographic studies of the genus Asarum.

Anti-Inflammatory Lignans from the Roots of Asarum heterotropoides var. mandshuricum and Their Mechanism of Action

Bioassay-guided fractionation of Asarum heterotropoides var. mandshuricum F. Maekawa (Aristolochiaceae) root extract led to the isolation and characterization of one new ferulic acid glucose ester (1) and nine known lignans (2-10). Their structures were elucidated using extensive spectroscopic methods, including 1D and 2D NMR, and MS spectra. The anti-inflammatory effects of the isolated compounds were investigated via their inhibition against nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW264.7 mouse macrophage cells. Among them, compound 7 ((1R,2S,5R,6R)-5'-O-methylpluviatilol) showed the most effective inhibitory activity against NO production and expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein in an exceedingly dose-dependent manner. In addition, further study revealed that the mechanism of anti-inflammatory activity of the most active lignan (7) might be associated with the inhibition of extracellular-signal-regulated kinase (ERK) and nuclear factor kappa B (NF-κB) phosphorylation.

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.

The complete chloroplast genome of Asarum pulchellum Hemsl. (Aristolochiaceae: Asarum L.)

Asarum pulchellum Hemsley 1890, belonging to Aristolochiaceae family, is a kind of folk herb resource with certain toxicity. In this study, we acquired the complete chloroplast genome of A. pulchellum for its accurate species identification and phylogenetic analysis. The genome is 177,905 bp in size with a typical circular quadripartite structure, consisting of a large single-copy region, a small single-copy region and a pair of inverted repeats. In total, 136 genes were annotated, including 92 protein-coding genes, 36 tRNA genes and eight rRNA genes. In the phylogenetic analysis, A. pulchellum and A. sieboldii formed a sister clade. The chloroplast genome helps further studies of taxonomy and genetic evolution of Aristolochiaceae family.

Ethno-pharmacology of Asaroon (Asarum europaeum L.) with special reference to Unani System of Medicine

Asaroon is the rhizome of Asarum europaeum L. and is commonly used in Unani medicines for its various pharmacological actions. It is an evergreen plant with glossy foliage. It belongs to the family of Aristolochiaceae and is native to Europe and the United State of America. Some species of Asaroon have been found in the Eastern Himalayan region. Asaroon has actions like Muharrik-i-A'sab (nervine stimulant), Mudirr-i-Bawl (diuretics), Mudirr-i-Hayd (emmenagogue), Musakkin-i-Alam (analgesic), Mufattit-i-sudad (remove obstructions) and Muqawwī-i-Jigar (hepatotonic), etc. It is used in the management of Hummā (fevers), Waja 'al-Mafasil (polyarthritis), Sara (epilepsy), Falij (paralysis), Ihtibās al-Tamth (amenorrhea) and Niqris (gout), etc. as per the Unani system of medicine (USM). It is used as a single herb as well as with a combination of other drugs to manage many diseases. The A. europaeum L. contains volatile oils and flavonoids along with other secondary metabolites. In the Indian market, Valeriana wallichii DC has been sold as Tagar but in some cases, it is sold as Asaroon. It is a clear case of adulteration by replacement of costly foreign drugs with a similar-looking indigenous drug. In this manuscript, we have discussed the Ethno-pharmacology of the A. europaeum L. with special reference to USM and basic differences with V. wallichii DC to show that both drugs are different and their actions and uses are also different from each other.

Beneficial Medicinal Plants for Memory and Cognitive Functions Based on Traditional Persian Medicine

Alzheimer's disease (AD) is one of the most important causes of dementia, especially in the elderlies. Due to the failures of recent clinical trials in finding effective medications, it appears the use of complementary therapies such as Traditional Persian Medicine (TPM) and the rich sources of effective herbs as well as their constituents for improving memory function could be beneficial. The aim of this study was to evaluate the recommended natural remedies in the TPM and examine their pharmacological properties. For this purpose, the data were collected by searching the recommended prescriptions of the seminal TPM textbooks. Then, the names of the most freuqently mentioned plants were extracted from the natural remedies and evaluated for their pharmacological properties. The sources included recently published articles cited in the major scientific databases. A total of 262 plants were identified in 96 evaluated prescriptions; 20 plants were identified with the most frequency of report (i.e. more than 10 times). Their neuroprotective effects, antioxidant features, and anti-AD properties were discussed. Based on our results, TPM has introduced many effective treatments for AD. Hence, more clinical studies are warranted to verify their efficacy and safety.

Comparative Transcriptomics Analysis for Gene Mining and Identification of a Cinnamyl Alcohol Dehydrogenase Involved in Methyleugenol Biosynthesis from Asarum sieboldii Miq

Asarum sieboldii Miq., one of the three original plants of TCM ASARI RADIX ET RHIZOMA, is a perennial herb distributed in central and eastern China, the Korean Peninsula, and Japan. Methyleugenol has been considered as the most important constituent of Asarum volatile oil, meanwhile asarinin is also employed as the quality control standard of ASARI RADIX ET RHIZOMA in Chinese Pharmacopeia. They both have shown wide range of biological activities. However, little was known about genes involved in biosynthesis pathways of either methyleugenol or asarinin in Asarum plants. In the present study, we performed de novo transcriptome analysis of plant tissues (e.g., roots, rhizomes, and leaves) at different developmental stages. The sequence assembly resulted in 311,597 transcripts from these plant materials, among which 925 transcripts participated in 'secondary metabolism' with particularly up to 20.22% of them falling into phenylpropanoid biosynthesis pathway. The corresponding enzymes belong to seven families potentially encoding phenylalanine ammonia-lyase (PAL), trans-cinnamate 4-monooxygenase (C4H), p-coumarate 3-hydroxylase (C3H), caffeoyl-CoA O-methyltransferase (CCoAOMT), cinnamoyl-CoA reductase (CCR), cinnamyl alcohol dehydrogenase (CAD), and eugenol synthase (EGS). Moreover, 5 unigenes of DIR (dirigent protein) and 11 unigenes of CYP719A (719A subfamily of cytochrome P450 oxygenases) were speculated to be involved in asarinin pathway. Of the 15 candidate CADs, four unigenes that possessed high FPKM (fragments per transcript kilobase per million fragments mapped) value in roots were cloned and characterized. Only the recombinant AsCAD5 protein efficiently converted p-coumaryl, coniferyl, and sinapyl aldehydes to their corresponding alcohols, which are key intermediates employed not only in biosynthesis of lignin but also in that of methyleugenol and asarinin. qRT-PCR revealed that AsCAD5 had a high expression level in roots at three developmental stages. Our study will provide insight into the potential application of molecular breeding and metabolic engineering for improving the quality of TCM ASARI RADIX ET RHIZOMA.

Phylogenetic relationships in Asarum: Effect of data partitioning and a revised classification

PREMISE OF THE STUDY

Generic boundaries and infrageneric relationships among the charismatic temperate magnoliid Asarum sensu lato (Aristolochiaceae) have long been uncertain. Previous molecular phylogenetic analyses used either plastid or nuclear loci alone and varied greatly in their taxonomic implications for the genus. We analyzed additional molecular markers from the nuclear and plastid genomes, reevaluated the possibility of a derived loss of autonomous self-pollination, and investigated the topological effects of matrix-partitioning-scheme choice.

METHODS

We sequenced seven plastid regions and the nuclear ITS1-ITS2 region of 58 individuals representing all previously recognized Asarum s.l. segregate genera and the monotypic genus Saruma. Matrices were partitioned using common a priori partitioning schemes and PartitionFinder.

KEY RESULTS

Topologies that were recovered using a priori partitioning of matrices differed from those recovered using a PartitionFinder-selected scheme, and by analysis method. We recovered six monophyletic groups that we circumscribed into three subgenera and six sections. Putative fungal mimic characters served as synapomorphies only for subgenus Heterotropa. Subgenus Geotaenium, a new subgenus, was recovered as sister to the remainder of Asarum by ML analyses of highly partitioned datasets. Section Longistylis, also newly named, is sister to section Hexastylis.

CONCLUSIONS

Our analyses do not unambiguously support a single origin for all fungal-mimicry characters. Topologies recovered through the analysis of PartitionFinder-optimized matrices can differ drastically from those inferred from a priori partitioned matrices, and by analytical method. We recommend that investigators evaluate the topological effects of matrix partitioning using multiple methods of phylogenetic reconstruction.