Ethnic, Botanic, Phytochemistry and Pharmacology of the Acorus L. Genus: A Review

The genus Acorus, a perennial monocotyledonous-class herb and part of the Acoraceae family, is widely distributed in the temperate and subtropical zones of the Northern and Southern Hemispheres. Acorus is rich in biological activities and can be used to treat various diseases of the nervous system, cardiovascular system, and digestive system, including Alzheimer's disease, depression, epilepsy, hyperlipidemia, and indigestion. Recently, it has been widely used to improve eutrophic water and control heavy-metal-polluted water. Thus far, only three species of Acorus have been reported in terms of chemical components and pharmacological activities. Previously published reviews have not further distinguished or comprehensively expounded the chemical components and pharmacological activities of Acorus plants. By carrying out a literature search, we collected documents closely related to Acorus published from 1956 to 2022. We then performed a comprehensive and systematic review of the genus Acorus from different perspectives, including botanical aspects, ethnic applications, phytochemistry aspects, and pharmacological aspects. Our aim was to provide a basis for further research and the development of new concepts.

Acorus calamus var. angustatus Besser: Insight into current research on ethnopharmacological use, phytochemistry, pharmacology, toxicology, and pharmacokinetics

A. calamus var. angustatus Besser is an important traditional medicinal herb commonly used in China and other Asian countries. This study is the first systematic review of the literature to thoroughly analyze the ethnopharmacological application, phytochemistry, pharmacology, toxicology and pharmacokinetic properties of A. calamus var. angustatus Besser and provides a rationale for future research and prospects for application in clinical treatment. Information on relevant studies investigating A. calamus var. angustatus Besser was collected from SciFinder, the Web of Science, PubMed, CNKI, Elsevier, ResearchGate, ACS, Flora of China, and Baidu Scholar, etc. up to December 2022. In addition, information was also obtained from Pharmacopeias, books on Chinese herbal classics, local books, as well as PhD and MS dissertations. A. calamus var. angustatus Besser has played an important role in the herbal treatment of coma, convulsion, amnesia, and dementia for thousands of years. Studies investigating the chemical constituents of A. calamus var. angustatus Besser have isolated and identified 234 small-molecule compounds and a few polysaccharides. Among them, simple phenylpropanoids represented by asarone analogues and lignans are the two main active ingredients, which can be considered characteristic chemotaxonomic markers of this herb. In vitro and in vivo pharmacological studies indicated that crude extracts and active compounds from A. calamus var. angustatus Besser display a wide range of pharmacological activities, especially as treatment for Alzheimer's disease (AD), and anticonvulsant, antidepressant-like, anxiolytic-like, anti-fatigue, anti-Parkinson, neuroprotection, and brain protection properties, providing more evidence to explain the traditional medicinal uses and ethnopharmacology. The clinical therapeutic dose of A. calamus var. angustatus Besser does not present any toxic effects, but its main active ingredients α-asarone and β-asarone at excessive dose may lead to toxicity, and in particular, their respective epoxide metabolites may exert potential toxicity to the liver. This review provides a reference and further information for the future development and clinical application of A. calamus var. angustatus Besser.

New Spiro-Sesquiterpenoids from the Marine Sponge Myrmekioderma sp

Three new spiro-sesquiterpenoids, myrmekiones A-C (1-3), were isolated from the marine sponge Myrmekioderma sp. collected from the South China Sea. The structures of 1-3 were experimentally illuminated though comprehensive NMR spectra, X-ray diffraction analysis and calculated ECD. These three compounds possessed a special spiro skeleton. Compound 1 was characterized by a chamigrane-type structure, it is the first time to obtain the single-crystal of this type of oil compounds. 2 and 3 were a pair of diastereoisomers that possessed an acorane skeleton. This study expands the chemical diversity of marine origin spiro-metabolites.

Biotransformation of α-asarone by Alternaria longipes CGMCC 3.2875

Biotransformation of α-asarone by Alternaria longipes CGMCC 3.2875 yielded two pairs of new neolignans, (+) (7S, 8S, 7'S, 8'R) iso-magnosalicin (1a)/(-) (7R, 8R, 7'R, 8'S) iso-magnosalicin (1b) and (+) (7R, 8R, 7'S, 8'R) magnosalicin (2a)/(-) (7S, 8S, 7'R, 8'S) magnosalicin (2b), and four known metabolites, (±) acoraminol A (3), (±) acoraminol B (4), asaraldehyde (5), and 2, 4, 5-trimethoxybenzoic acid (6). Their structures, including absolute configurations, were determined by extensive analysis of NMR spectra, X-ray crystallography, and quantum chemical ECD calculations. The cytotoxic activity and Aβ₄₂ aggregation inhibitory activity of all the compounds were evaluated. Compound 2 displayed significant anti-Aβ₄₂ aggregation activity with an inhibitory rate of 60.81% (the positive control EGCG: 69.17%). In addition, the biotransformation pathway of α-asarone by Alternaria longipes CGMCC 3.2875 was proposed.

New Techniques of Structure Elucidation for Sesquiterpenes

The most significant new techniques that have been used in the twenty-first century for the structure elucidation of sesquiterpenes and some derivatives are reviewed in this chapter. A distinctive feature of these methodologies is the combination of accurate experimental measurements with theoretical data obtained by molecular modeling calculations that allow to visualize, understand, and quantify many structural characteristics. This has been the case for NMR spectroscopy, which has expanded its potential for solving complex structural problems by means of comparison with quantum mechanical molecular models. Ab initio and density functional theory calculations of chemical shifts, coupling constants, and residual chemical shift anisotropies have played important roles in the solution of many structures of sesquiterpenes. The assignments of their absolute configurations by evaluation of calculated and experimental chiroptical properties as electronic and vibrational circular dichroism are also reviewed. This chapter also includes the use of X-ray diffraction analysis with emphasis on calculations of the Flack and Hooft parameters, which are applicable to all molecules that crystallize in non-centrosymmetric space groups. The accurate molecular models of sesquiterpenes, validated by concordance with their experimental properties, are nowadays essential for the interpretation of the effects of these natural products on biological systems.

A New Brominated Norsesquiterpene Glycoside From the Rhizomes of Acorus tatarinowii Schott

A new brominated norsesquiterpene glycoside, acoruside (1), has been isolated from the rhizomes of Acorus tatarinowii Schott, together with 8 known compounds (2-9). Their structures were elucidated mainly based on 1-dimensional (1D) and 2D nuclear magnetic resonance spectra. The absolute configuration of compound 1 was determined by comparing its experimental and calculated electronic circular dichroism spectra. The in vitro tests indicated that at 10 µM, compounds 2, 3, and 4 aggravated serum deprivation injuries of PC12 cells, compound 2 aggravated rotenone-induced injuries of PC12 cells, and compounds 3 and 4 aggravated the oxygen-glucose deprivation-induced injuries of PC12 cells.

Sesquiterpenoids of diverse types from the rhizomes of Acorus calamus

Six new and fourteen known sesquiterpenoids of diverse types were isolated from the rhizomes of Acorus calamus.

Bioguided isolation, identification and activity evaluation of antifungal compounds from Acorus tatarinowii Schott

ETHNOPHARMACOLOGY RELEVANCE

As a traditional folk medicine, Acorus tatarinowii Schott was used to treat digestive diseases, such as diarrhea, which may be related to Candida albicans infection; however according to literature surveys, there have been few studies of A. tatarinowii focusing on its antimicrobial activity, and almost all describe investigations using crude extracts or fractions.

AIM OF THE STUDY

The aims of the current study were to isolate and identify antifungal fractions of A. tatarinowii based on their antifungal activity, explore the preliminary mechanism of 60% ethanol elution (AT60) by metabonomics, and evaluate the antifungal activity of AT60 in vivo and in vitro, to provide natural resources against fungal infections.

MATERIALS AND METHODS

As a pilot evaluation of activity, A. tatarinowii fractions and compounds with antifungal bioactivity were isolated by bioactive-guided column chromatography, and identified by LC-QTOF-MS/MS and NMR spectroscopy. The antifungal effects of the active ingredients against resistant C. albicans were evaluated by in vivo and in vitro colony forming unit assays. The mechanism underlying the activity of AT60 against C. albicans was explored using an LC-QTOF-based metabonomics approach and fluorescence microscopy imaging.

RESULTS

AT60 showed better activity against C. albicans than the same dose of the first line antifungal drugs, fluconazole and itraconazole (positive control drugs). Subsequent phytochemical investigation of AT60 identified twenty-five known compounds, six of which were isolated: asaraldehyde (7), 1-(2,4,5-trimethoxyphenyl)-1,2-propanediol (12), α-asarone (14), β-asarone (15), γ-asarone (18), acotatarone C (19). Further, the compounds α-asarone (14) and acotatarone C (19) may be responsible for the antifungal activity, and exhibit synergistic effects. Metabonomics analysis indicated that AT60 can inhibit biofilm formation by regulating the C. albicans protein kinase C pathway.

CONCLUSIONS

Our results show that A. tatarinowii has potent bioactivity against C. albicans in vitro and in vivo, and can be considered an antifungal botanic agent.

Bioactive Asarone-Derived Phenylpropanoids from the Rhizome of Acorus tatarinowii Schott

Eight new (1a/1b, 2a, 3a, 4a/4b, and 5a/5b) and seven known (2b, 3b, and 6-10) asarone-derived phenylpropanoids, a known asarone-derived lignan (12), and four known lignan analogues (11 and 13-15) were isolated from the rhizome of Acorus tatarinowii Schott. The structures were elucidated via comprehensive spectroscopic analyses, modified Mosher's method, and quantum chemical calculations. Compounds 1-8 were present as enantiomers, and 1-5 were successfully resolved via chiral-phase HPLC. Compounds 1a/1b were the first cases of asarone-derived phenylpropanoids with an isopropyl C-3 side-chain tethered to a benzene core from nature. Hypoglycemic, antioxidant, and AChE inhibitory activities of 1-15 were assessed by the α-glucosidase inhibitory, ORAC, DPPH radical scavenging, and AChE inhibitory assays, respectively. All compounds except 3a showed α-glucosidase inhibitory activity. Compound 3b has the highest α-glucosidase inhibitory effect with an IC₅₀ of 80.6 μM (positive drug acarbose IC₅₀ of 442.4 μM). In the antioxidant assays, compounds 13-15 exhibited ORAC and DPPH radical scavenging activities. The results of the AChE inhibitory assay indicated that all compounds exhibited weak AChE inhibitory activities.

New cadinane sesquiterpenoids from the basidiomycetous fungus Pholiota sp

The basidiomycetous fungus Pholiota sp. produced five new cadinane sesquiterpenoids pholiotins A–E (1–5). The absolute configurations were determined by X-ray diffraction, the Snatzke's method and electronic circular dichroism (ECD) calculations.

(±)-Acortatarinowins A-F, Norlignan, Neolignan, and Lignan Enantiomers from Acorus tatarinowii

Three pairs of new 8-O-4'-type dinorneolignan enantiomers, (±)-acortatarinowins A-C (1a/1b-3a/3b), a pair of new 8-O-4'-type (4a/4b) and a pair of rare C7-C8'-type (5a/5b) neolignan enantiomers, (±)-acortatarinowins D and E, and a pair of new furofuran-type lignan enantiomers, (±)-acortatarinowin F (6a/6b), along with two pairs of known lignan enantiomers (7a/7b and 8a/8b), were obtained from the rhizomes of Acorus tatarinowii. The separation of 1-8 by chiral HPLC using a Daicel IC column led to the isolation of eight pairs of enantiomers, 1a/1b-8a/8b, which had variable enantiomeric excess (ee) values of approximately 66, 71, 63, 60, 0, 38, 48, and 75%, respectively. The structures were elucidated by extensive spectroscopic and chemical methods, and their absolute configurations were determined by a combined analysis of single-crystal X-ray diffraction and a modified Mosher's method, assisted by experimental and calculated electronic circular dichroism data. Among them, compounds 1a, 3a, 6b, 8a, and 8b showed weak inhibitory activities against NO production in activated macrophages with IC50 values ranging from 23.3 to 38.0 μM, respectively.

Bioactive sesquiterpene quinols and quinones from the marine sponge Dysidea avara

Reports the isolation, structure determination, and cytotoxic and NF-κB inhibitory activities of eight sesquiterpene quinols and quinones from Dysidea avara.

Acorus Linnaeus: a review of traditional uses, phytochemistry and neuropharmacology

Acorus Linnaeus is a herb used in many ancient medicinal systems. Phytochemical and neuropharmacological studies have revealed that many beneficial compounds possessed anticonvulsant, antiepileptic, neuroprotective, memory enhancing, and sedative properties.