Preparative isolation of three anthraquinones from Rumex japonicus by high-speed counter-current chromatography

Recent research on the physicochemical properties and biological activities of quinones and their practical applications: a comprehensive review

Quinones represent a class of crude organic compounds ubiquitously distributed in nature. Their distinctive quinone-type structure confers upon them unique properties and applications. Quinones demonstrate significant biological activities, including antioxidant, antimicrobial, and antitumor properties. Additionally, they demonstrate noteworthy physicochemical characteristics, including excellent dyeing properties and stability. Given their diverse qualities, quinones hold significant promise for applications in industrial manufacturing, healthcare, and food production, thus garnering considerable attention in recent years. While there is a growing body of research on quinones, the existing literature falls short of providing a comprehensive review encompassing recent advancements in this field along with established knowledge. This paper offers a comprehensive review of research progress for quinones, encompassing structural classification, source synthesis, extraction methods, properties, functions, and specific applications. It serves as a reference and theoretical foundation for the further development and utilization of quinones.

Study on the chemical composition and anti-fungi activities of anthraquinones and its glycosides from Rumex japonicus Houtt

Fungi, such as Trichophyton rubrum (T. rubrum) and Microsporum canis Bodin Anamorph (M. canis Bodin Anamorph) are the main pathogens of dermatophysis. According to ancient books records, Rumex japonicus Houtt. (RJH) has a miraculous effect on the treatment of dermatophysis. To reveal the anti-fungi (T. rubrum and M. canis Bodin Anamorph) components and its mechanism of the Rumex japonicus Houtt. The vinegar extraction and alcohol precipitation, HPLC and nuclear magnetic resonance spectroscopy (NMR) were employed for analyzing the chemical compositions of RJH; in vitro anti-fungal experiment was investigated including test the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC), spore germination rate, nucleic acid, protein leakage rate, biofilm structure, and the mechanism of anti-fungal and anti-fungal biofilms in RJH. Seven anthraquinones and their glycoside compounds were obtained in this study respectively, such as chrysophanol, physcion, aloe-emodin, emodin, rhein, emodin-8-O-β-D-glucoside and chrysophanol-8-O-β-D-glucoside. In vitro anti-fungal experiment results showed that RJH extracts have good anti-fungal activity for dermatophytic fungi. Among them, the MIC of the rhein, emodin and aloe-emodin against T. rubrum are 1.9 µg/ml, 3.9 µg/ml and 15.6 µg/ml, respectively; the MIC of emodin and aloe-emodin against M. canis Bodin Anamorph are 7.8 µg/ml and 62.5 µg/ml, respectively. In addition, its active components can inhibit fungal spore germination and the formation of bud tube, change cell membrane permeability, prevent hyphal growth, destroy biofilm structure, and down-regulate the expression of agglutinin-like sequence family 1 of the adhesion phase of biofilm growth. The study shows that RJH play a fungicidal role.

Simultaneous high-performance liquid chromatography analysis of anthraquinones in sicklepod sprouts with α-glucosidase inhibitory activity

INTRODUCTION

Sicklepod [Cassia obtusifolia L. syn Senna obtusifolia (L.) H.S. Irwin & Barneby, Fabaceae] sprouts are promising ingredients with health-promoting benefits. Notwithstanding, the pharmacologically active compounds in sicklepod sprouts have not been studied or analysed in detail.

OBJECTIVE

This study aimed to isolate and structurally identify phytochemicals showing α-glucosidase inhibitory activity in sicklepod sprouts and simultaneously quantify the compounds in the sprouts to determine the optimal cultivation method and germination time to maximise active compounds.

METHOD

A simultaneous high-performance liquid chromatography-ultraviolet (HPLC-UV) method with high sensitivity and accuracy was developed and used to analyse time-dependent changes in anthraquinone content during sicklepod germination.

RESULTS

Thirteen anthraquinones were isolated and identified, of which six-chrysoobtusin, emodin, 1-O-methyl-2-methoxychrysophanol, 7-O-methylobtusin, chrysophanol, and physcion-showed moderate α-glucosidase inhibitory activity. The maximum content of anthraquinones in a sprout was observed on Day 5 under both light and dark conditions.

CONCLUSION

The findings of this study revealed that sicklepod sprouts which are promising functional food materials contain a variety of anthraquinones.

Chemical Constituents from Berchemia polyphylla var. Leioclada

One previously undescribed naphthoquinone-benzisochromanquinone dimer berpolydiquinone A (1), along with two previously undescribed naphthoquinone-anthraquinone dimers berpolydiquinones B and C (2-3), and one previously undescribed dimeric naphthalene berpolydinaphthalene A (4), were isolated from the stems and leaves of Berchemia polyphylla var. leioclada. The chemical structures of these compounds were determined using high-resolution electrospray ionization mass spectroscopy (HR-ESI-MS), spectroscopic data, the exciton chirality method (ECM), and quantum chemical calculation. Notably, compounds (1-2 and 5) are dimeric quinones that share the same naphthoquinone moiety, specifically identified as 2-methoxystypandron. Compound (4) is a derivative of dimeric naphthalene with a symmetrical structure, which is a new structure type isolated from B. polyphylla var. leioclada for the first time. These findings suggest that B. polyphylla var. leioclada serves as a significant reservoir of structurally diverse phenolic compounds. This study provides a scientific foundation for regarding B. polyphylla var. leioclada as a potential source of "Tiebaojin".

Quinones: Biosynthesis, Characterization of 13 C Spectroscopical Data and Pharmacological Activities

Quinones are natural products widely distributed in nature, which are involved in stages of several vital biological processes, with mostly having a variety of pharmacological properties. The main groups comprising most of these compounds are benzoquinones, naphthoquinones, anthraquinones, and phenanthraquinones. Quinone isolation has been a focus of study around the world in recent years; for this reason, this study approaches the junction of natural quinones identified by 13 C Nuclear Magnetic Resonance (NMR) spectroscopic analytical techniques. The methodology used to obtain the data collected articles from various databases on quinones from 2000 to 2022. As a result, 137 compounds were selected, among which 70 were characterized for the first time in the period investigated; moreover, the study also discusses the biosynthetic pathways of quinones and the pharmacological activities of the compounds found, giving an overview of the various applications of these compounds.

Antibacterial constituents of Rumex nepalensis spreng and its emodin derivatives

The CH2Cl2-MeOH (1:1) extract of roots of Rumex nepalensis (Polygonaceae) displayed significant antibacterial activity against five bacterial strains with MICs (62.5-31.2 μg.mL-1). The EtOAc soluble fraction displayed a significant activity against the same strains with MICs (31.2-3.9 μg.mL-1). The purification of the EtOAc fraction yielded one new phenylisobenzofuranone derivative, berquaertiide (1), along with 19 known compounds (2-20). Their structures were elucidated based on the analysis of their NMR and MS data. All the isolated compounds were assessed for their antibacterial activity. Compound 2 was the most active against all the tested strains (15.7 to 1.9 μg.mL-1), while compounds 3-7 displayed good activities on at least one of the tested strains. In addition, seven analogues (21-27) of compound 2 were prepared and further assessed for their antibacterial activity. Compounds 26 and 27 were most active than 2 against Salmonella enterica and Klebsiella pneumoniae with MIC (125 and 15.6 μg.mL-1, respectively).

Facile and selective separation of anthraquinones by alizarin-modified iron oxide magnetic nanoparticles

Anthraquinones are widely distributed in higher plants and possess broad biological activities. The conventional separation procedures for isolating anthraquinones from the plant crude extracts require multiple extraction, concentration, and column chromatography steps. In this study, we synthesized three alizarin (AZ)-modified Fe₃O₄ nanoparticles (Fe₃O₄@AZ, Fe₃O₄@SiO₂-AZ, and Fe₃O₄@SiO₂-PEI-AZ) by thermal solubilization method. Fe₃O₄@SiO₂-PEI-AZ showed strong magnetic responsiveness, high methanol/water dispersion, good recyclability, and high loading capacity for anthraquinones. To evaluate the feasibility of using Fe₃O₄@SiO₂-PEI-AZ for separating various aromatic compounds, we employed molecular dynamics simulations to predict the adsorption/desorption effects of PEI-AZ for various aromatic compounds in different methanol concentrations. The results showed that the anthraquinones could be efficiently separated from the monocyclic and bicyclic aromatic compounds by adjusting the methanol/water ratio. The Fe₃O₄@SiO₂-PEI-AZ nanoparticles were then used to separate the anthraquinones from the rhubarb extract. At 5% methanol, all the anthraquinones were adsorbed by the nanoparticles, thus allowing their separation from other components in the crude extract. Compared with the conventional separation methods, this adsorption method has the advantages of high adsorption specificity, simple operation, and solvent saving. This method sheds light on the future application of functionalized Fe₃O₄ magnetic nanoparticles to selectively separate desired components from complex plant and microbial crude extracts.

Phytochemical Investigation, In Silico/In Vivo Analgesic, and Anti-inflammatory Assessment of the Egyptian Cassia occidentalis L

Cassia occidentalis L., from Fabaceae family phytochemical screening, revealed several biologically active principles mainly flavonoids and anthraquinones. GLC analysis of the lipoidal matter afforded 12 hydrocarbons: 9-dodecyl-tetradecahydro-anthracene (48.97 %), 9-dodecyl-tetradecahydro-phenanthrene (14.43 %), and 6 sterols/triterpenes: iso-jaspisterol (11.99%) and fatty acids were palmitic acid (50 %), and Linoleic acid (16.06%). Column chromatography led to the isolation of fifteen compounds (1-15), elucidated using spectroscopic evidence. First report of undecanoic acid (4) from the family Fabaceae, while p-dimethyl amino-benzaldehyde (15) was first time isolated from a natural origin. Eight compounds isolated for the first time from C. occidentalis L.; β-amyrin (1), β-sitosterol (2), stigmasterol (3), camphor (5), lupeol (6), chrysin (7), pectolinargenin (8), and 1, 2, 5-trihydroxy anthraquinone (14) besides five known compounds previously isolated; apigenin (9), kaempferol (10), chrysophanol (11), physcion (12), and aloe-emodin (13). In-vivo evaluation of anti-inflammatory and analgesic effects of C. occidentalis L. extracts where the n-butanol and total extracts showed the highest activities. The percentage of the inhibitory effect of the n-butanol extract was 29.7 at a dose of 400 mg/Kg. Furthermore, identified phytoconstituents were docked into the active sites of enzymes nAChRs, COX-1, and COX-2 to evaluate binding affinity. Phyto-compounds Physcion, aloe-emodin, and chrysophanol were found to have a good affinity for targeted receptors compared to co-crystalized inhibitors, validating the analgesic and anti-inflammatory effects of the phytochemicals.

Bio-efficacy of insecticidal molecule emodin against dengue, filariasis, and malaria vectors

Emodin, a compound isolated from Aspergillus terreus, was studied using chromatographic and spectroscopic methods and compound purity (96%) was assessed by TLC. Furthermore, high larvicidal activity against Aedes aegypti-AeA (LC₅₀ 6.156 and LC₉₀ 12.450 mg/L), Culex quinquefasciatus-CuQ (8.216 and 14.816 mg/L), and Anopheles stephensi-AnS larvae (6.895 and 15.24 mg/L) was recorded. The first isolated fraction (emodin) showed higher pupicidal activity against AeA (15.449 and 20.752 mg/L). Most emodin-treated larvae (ETL) showed variations in acetylcholine esterase, α and β-carboxylesterases, and phosphatase activities in the 4^th instar, indicating the intrinsic differences in their biochemical changes. ETL had numerous altered tissues, including muscle, gastric caeca, hindgut, midgut, nerve ganglia, and midgut epithelium. Acute toxicity of emodin on brine shrimp Artemia nauplii (54.0 and 84.5 mg/L) and the zebrafish Danio rerio (less toxicity observed) was recorded. In docking studies, Emodin interacted well with odorant-binding-proteins of AeA, AnS, and CuQ with docking scores of - 8.89, - 6.53, and - 8.09 kcal mol^-1, respectively. Therefore, A. terreus is likely to be effective against mosquito larvicides.

Bioactive Secondary Metabolites from Fungi of the Genus Cytospora Ehrenb. (Ascomycota)

Cytospora is a genus of fungi belonging to the Cytosporaceae family (Sordariomycetes, Ascomycota) considered as a prolific source of specialized metabolites due to their ability to produce diverse secondary metabolites with a broad range of biological activities. Since the first chemical investigation of this genus in the 1980s, further studies have led to the isolation and structural elucidation of several bioactive compounds including cytosporones, nonanolides, macrocyclic dilactones, and terpenoids. This review summarizes, for the first time, the chemical diversity of bioactive secondary metabolites from the genus Cytospora and highlights its potential as an alternative source of secondary metabolites for pharmacological studies. Moreover, this review will serve as a basis for future investigations of compounds of this genus.

Isolation and acetylcholinesterase inhibitory activity of asterric acid derivatives produced by Talaromyces aurantiacus FL15, an endophytic fungus from Huperzia serrata

Alzheimer's disease (AD) is a neurodegenerative disease and the fourth leading cause of death after cardiovascular disease, tumors, and stroke. Acetylcholinesterase (AChE) inhibitors, which are based on cholinergic damage, remain the mainstream drugs to alleviate AD-related symptoms. This study aimed to explore novel AChE inhibitors produced by the endophytic fungus FL15 from Huperzia serrata. The fungus was identified as Talaromyces aurantiacus FL15 according to its morphological characteristics and ITS, 18S rDNA, and 28S rDNA sequence analysis. Subsequently, seven natural metabolites were isolated from strain FL15, and identified as asterric acid (1), methyl asterrate (2), ethyl asterrate (3), emodin (4), physcion (5), chrysophanol (6), and sulochrin (7). Compounds 1-3, which possess a diphenyl ether structure, exhibited highly selective and moderate AChE inhibitory activities with IC₅₀ values of 66.7, 23.3, and 20.1 μM, respectively. The molecular docking analysis showed that compounds 1-3 interacted with the active catalytic site and peripheral anionic site of AChE, and the esterification substitution groups at position 8 of asterric acid may contribute to its bioactivity. The asterric acid derivatives showed highly selective and moderate AChE inhibitory activities, probably via interaction with the peripheral anionic site and catalytic site of AChE. To the best of our knowledge, this study was the first report of the AChE inhibitory activity of asterric acid derivatives, which opens new perspectives for the design of more effective derivatives that could serve as a drug carrier for new chemotherapeutic agents to treat AD.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-022-03125-2.

Antibacterial, antifungal and antioxidant activities of whole plant chemical constituents of Rumex abyssinicus

Background

Antibiotic resistance has contributed to the burden of infectious diseases both in the hospital and community setting, and represents a great threat to public health. Previous studies have revealed the role of reactive oxygen species as intermediate mediators of tissue damage, following antibiotherapies, indicating the need of associating antioxidants to these treatments. Therefore, the present work was designed to study the antibacterial, antifungal and antioxidant activities of extracts and compounds from Rumex abyssinicus Jacq. (Polygonaceae), as well as to investigate the antibacterial mechanisms of action of the most effective agents.

Methods

The plant extracts were prepared by maceration in organic solvents followed by column chromatography of the EtOAc fraction and purification of different fractions which led to the isolation and characterization of pure compounds. The antimicrobial activities of the extracts/compounds and their combinations with ciprofloxacin and fluconazole were evaluated using the broth microdilution method by determining the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC). The effects of the extracts on the bacterial cell membrane and microbial respiratory chain dehydrogenase enzyme activity were determined by spectrophotometric methods. Antioxidant activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and gallic acid equivalent antioxidant capacity (GAEAC) assays.

Results

Chrysophanol (1), physcion (2), Ergosta-6,22-diene-3,5,8-triol (3), emodin (4), 6-hydroxyemodin (citreorosein) (5), chrysophanein (6) and physcionin (7) were isolated from EtOAc fraction of R. abyssinicus and displayed different degrees of antimicrobial activities (MIC = 8–256 μg/mL). The MeOH extract and compounds 2 and 4 exhibited synergistic effects with ciprofloxacin and fluconazole. Compounds 1, 2 and the combined mixture of 6 + 7 displayed the highest antioxidant activity (GAEAC = 83.38–106.03 μg/mL).

Conclusion

R. abyssinicus is a potential source of antibacterial, antifungal and antioxidant agents. The antibacterial mechanisms of action of the MeOH extract and compound 2 are due to disruption of the cytoplasmic membrane and inhibition of the microbial respiratory chain dehydrogenase enzyme activity. To the best of our knowledge, this is the first report of test samples and ciprofloxacin / fluconazole association against MDR strains. The observed activity of the isolated compounds against bacteria and fungi including MDR strains deserves further exploration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03325-y.

Physcion Protects Rats Against Cerebral Ischemia-Reperfusion Injury via Inhibition of TLR4/NF-kB Signaling Pathway

Background

Ischemic stroke (IS) is characterized by the rapid loss of brain function due to ischemia. Physcion has been found to have a neuroprotective effect against cerebral ischemia-reperfusion (I/R) injury. However, the mechanism by which physcion regulates cerebral I/R injury remains largely unknown.

Methods

An oxygen-glucose deprivation/reperfusion (OGD/R) model in SH-SY5Y cells and a rat cerebral ischemia-reperfusion (I/R) model were established, respectively. CCK-8 and flow cytometry assays were used to detect the viability and apoptosis of SH-SY5Y cells. Moreover, enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of SOD, MDA, GSH-Px, TNF-α, IL-1β, IL-6 and IL-10 in the supernatant of SH-SY5Y cells. Meanwhile, Western blot assay was used to detect the expressions of TLR4, p-p65 and p-IκB in SH-SY5Y cells and I/R rats.

Results

In this study, physcion treatment significantly rescued OGD/R-induced neuronal injury. In addition, physcion decreased inflammatory response in SH-SY5Y cells after OGD/R insult, as shown by the decreased levels of the pro-inflammatory factors TNF-α, IL-1β, IL-6 and IL-10. Moreover, physcion attenuated the oxidative stress in OGD/R-treated SY-SY5Y cells, as evidenced by the increased SOD and GSH levels and the decreased ROS and MDA levels. Meanwhile, physcion significantly reduced cerebral infarction, attenuated neuronal injury and apoptosis in I/R rats. Furthermore, physcion markedly decreased the expressions of TLR4, p-NF-κB p65 and p-IκB in the brain tissues of rats subjected to I/R and in SH-SY5Y cells exposed to OGD/R.

Conclusion

In conclusion, our study indicated that physcion protected neuron cells against I/R injury in vitro and in vivo by inhibition of the TLR4/NF-kB pathway; thus, physcion might serve as a promising therapeutic candidate for IS.

Inhibition of Jurkat T Cell Proliferation by Active Components of Rumex japonicus Roots Via Induced Mitochondrial Damage and Apoptosis Promotion

Rumex japonicus Houtt (RJH) is a valuable plant used in traditional medicine to treat several diseases, such as scabies and jaundice. In this study, Jurkat cell growth inhibitory extracts of R. japonicus roots were subjected to bioassay-guided fractionation, resulting in the isolation of three naphthalene derivatives (3-5) along with one anthraquinone (6) and two phenolic compounds (1 and 2). Among these compounds, 2-methoxystypandrone (5) exhibited potent anti-proliferative effects on Jurkat cells. Analysis by flow cytometry confirmed that 2-methoxystypandrone (5) could significantly reduce mitochondrial membrane potential and promote increased levels of mitochondrial reactive oxygen species (ROS), suggesting a strong mitochondrial depolarization effect. Real-time quantitative polymerase chain reaction (qPCR) analysis was also performed, and the results revealed that the accumulation of ROS was caused by reduced mRNA expression levels of heme oxygenase (HO-1), catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD). In addition, 2-methoxystypandrone (5) triggered strong apoptosis that was mediated by the arrest of the G0/G1 phase of the cell cycle. Furthermore, 2-methoxystypandrone (5) downregulated p-IκB-α, p-NF-κB p65, Bcl2, and Bcl-xl and upregulated BAX proteins. Taken together, these findings revealed that 2-methoxystypandrone (5) isolated from RJH could potentially serve as an early lead compound for leukemia treatment involving intracellular signaling by increasing mitochondrial ROS and exerting anti-proliferative effects.

Matrix metalloproteinase inhibitor and sunscreen effective compounds from Rumex crispus L.: isolation, identification, bioactivity and molecular docking study

INTRODUCTION

Rumex (Polygonaceae) species are widely grown worldwide and their main compounds are anthranoids, tannins, naphthalenes and flavonoids. Matrix metalloproteinase (MMP) enzymes that cause the breakdown of the extracellular matrix and harmful ultraviolet (UV) rays are two important causes of skin ageing. Although there have been many studies on anthraquinones, there are not many studies on their anti-ageing effects.

OBJECTIVE

The aim of this study was to determine the anti-ageing effects of pure compounds isolated from Rumex crispus L. by measuring their MMP inhibitory and sunscreen activities.

METHODOLOGY

Molecular docking studies on anthranoid, flavonoid, tannin and naphthalene skeletons with MMP enzymes were applied for the first time. Various chromatographic methods were used for isolation studies. The structure elucidation was performed by spectroscopic [UV, infrared (IR), electrospray ionisation mass spectrometry (ESI-MS), nuclear magnetic resonance (NMR)] methods. To determine the anti-ageing capacity of compounds, MMP-1, MMP-8, MMP-13 enzyme inhibitory effects and sun protection factors (SPFs) were investigated for the first time.

RESULTS

Molecular docking results showed that skeletons had low binding energy to the target and were likely to inhibit MMP enzymes. Then, eight anthraquinones and a naphthalene glycoside were isolated from the underground parts of Rumex crispus L. According to the results, MMP inhibitory effects of compounds were found to be high. In vitro and molecular docking study results confirmed each other. All anthraquinones showed high sun protection and emodin showed highest UV capability with SPF of 30.59.

CONCLUSION

This study shows that anthraquinones may be evaluated as new potential MMP inhibitors, sun protective and anti-ageing agents.

The isolation of secondary metabolites from Rheum ribes L. and the synthesis of new semi-synthetic anthraquinones: Isolation, synthesis and biological activity

Rheum ribes L. (Rhubarb) is one of the most important edible medicinal plants in the Eastern Anatolia region and is called "Işkın" by local people. Resveratrol and 6-O-methylalaternin were isolated from the Rhubarb for the first time in addition to well-known secondary metabolites including emodin, aloe-emodin, β-sitosterol and rutin. The new semi-synthetic anthraquinone derivatives with the N^αFmoc-l-Lys and ethynyl group were synthesized from the isolated anthraquinones emodin and aloe-emodin of Rhubarb to increase the bioactivities. Aloe-emodin derivative with N^αFmoc-l-Lys shows the highest inhibition values by 94.11 ± 0.12 and 82.38 ± 0.00% against HT-29 and HeLa cell lines, respectively, at 25 µg/mL. Further, modification of the aloe-emodin with both the ethynyl and the N^αFmoc-l-Lys groups showed an antioxidant activity-enhancing effect. From molecular docking studies, the relative binding energies of the emodin and aloe-emodin derivatives to human serum albumin ranged from -7.30 and -10.62 kcal/mol.

Isolation of six anthraquinone diglucosides from cascara sagrada bark by high-performance countercurrent chromatography

In this study, high-performance countercurrent chromatography was employed to isolate six anthraquinone diglucosides, namely, cascarosides A-F, from cascara sagrada (Rhamnus purshiana DC [Rhamnaceae]) bark. The n-butanol-soluble extract of cascara sagrada was separated by off-line two-dimensional high-performance countercurrent chromatography. The first-dimensional high-performance countercurrent chromatography resolved the n-butanol-soluble extract (510 mg) of cascara sagrada using the flow-rate gradient method with a chloroform-methanol-isopropanol-water (6:6:1:4, v/v/v/v, normal-phase mode) system to afford four anthraquinone diglucoside fractions (groups I [cascarosides C-D, 71 mg], II [cascarosides E-F, 56 mg], III [cascaroside A, 53 mg], and IV [cascaroside B, 31 mg]). Groups I and II were separated by the second-dimensional high-performance countercurrent chromatography using an ethyl acetate-n-butanol-water (7:3:10, v/v/v, normal-phase mode) system to yield cascarosides C (34 mg), D (26 mg), E (19 mg), and F (15 mg). Additionally, one-step preparative-scale high-performance countercurrent chromatography method was developed to isolate large amounts of cascarosides A (389 mg) and B (187 mg) from the water-soluble extract (2.1 g) of cascara sagrada using an ethyl acetate-n-butanol-water (2:8:10, v/v/v, normal-phase mode) system. The current study demonstrated that high-performance countercurrent chromatography is a powerful technique for the isolation of marker compounds from herbal materials.

The complete plastome sequence of Rumex japonicus Houtt.: a medicinal plant

Rumex japonicus is a medicinal plant distributed in East Asia. Here, we report and characterize the complete plastid genome sequence of R. japonicus and size is 159,292 bp in length and contains the typical structure and gene content of other angiosperm plastomes, including two inverted repeat regions of 30,629 bp, a large single-copy region of 85,028 bp and a small single-copy region of 13,006 bp. There are 112 unique genes, including 78 protein-coding, 30 tRNAs and 4 rRNAs. We constructed a phylogenetic tree with 14 species and the phylogenetic topologies showed that R. japonicus was closely related to Rheum wittrockii.

Rumex japonicus Houtt.: A phytochemical, pharmacological, and pharmacokinetic review

Rumex japonicus Houtt. (RJH-Yang Ti) RJH has been used as a folk medicine in East Asian countries for thousands of years. It has a wide range of therapeutic effects in terms of anti-microorganic, anti-oxidant, anti-inflammatory, and antitumor effects. Therefore, it is urgent to thoroughly review the existing knowledge for this herb from phytochemical, pharmacological, and pharmacokinetic perspectives. "Yang Ti" and its English, botanical and pharmaceutical names used as keywords to perform database search which included the Encyclopaedia of traditional Chinese Medicines, PubMed, EMBASE, AMED, CINAHL, Cochrane Library, MEDLINE, Science Direct, Scopus, Web of Science, and China Network Knowledge Infrastructure. Forty-five compounds identified from RJH. Besides, the therapeutic effects of RJH have been summarized as well. The root of RJH contains derivatives of anthraquinones, phytosterols, nepodin, oxanthrone c-glycosides, phenolic acid, cinnamic acid, flavonoid, epoxynaphthoquinol, triterpenoids, methoxynaphthalene, trihydroxybenzene, anthracene-9,10-dione, and other compounds. The extract of RJH and its chemical compounds showed the potentials as a complementary agent to exert antioxidant, antimicrobial, antisepsis, anticancer, anti-haematological disease, anti-dermatological disease, and antidiabetic activities. For the record, there is no study conducted on RJH regarding its pharmacokinetic aspect. Notably, Emodin may require additional attention due to its multiple organ toxicity concerns.

Physcion reduces lipid accumulation and prevents the obesity in mice

Background

Obesity increases the risk of metabolic dysfunction such as dyslipidemia, hypertension, and fatty liver. Physcion (PY) is an anthraquinone that reportedly has anti-inflammatory and anti-bacterial properties. However, few studies have addressed the effect of PY on high-fat diet-induced obesity in mice. The purpose of this study was to investigate the effects of PY on obesity.

Methods

Male C57BL/6 J mice were randomly divided into three groups and fed normal diet (ND, 5% fat, w/w), high-fat diet (HFD, 20% fat, 1% cholesterol, w/w), and HFD supplemented with 0.002% PY (w/w) for 16 weeks. Obesity-related biomarkers were analyzed including whole body and white adipose tissue (WAT) weight, in addition to lipid and inflammatory factors in the plasma, feces, liver and epididymal WAT. Significant differences among the groups were determined using Student’s t-test. Differences were considered statistically significant at p < 0.05.

Results

Body and WAT weights were significantly decreased by the PY supplement relative to the HFD groups. Energy expenditure was enhanced by the PY supplement, which led to ameliorate plasma lipids, adipokines, cytokines, and fecal lipids. Fatty acid (FA) synthesis decreased in the liver, while FA oxidation increased. Finally, lipid synthesis markedly decreased whereas lipolysis and oxidation increased in WAT.

Conclusions

The PY supplement suppressed lipid accumulation in WAT and the liver by regulating enzyme and gene levels. These results indicate that PY can improve diet-induced obesity and its complications such as dyslipidemia, hepatic steatosis, and inflammation.

Antimicrobial activity and cytotoxicity of xanthoquinodin analogs from the fungus Cytospora eugeniae BCC42696

Eleven previously undescribed compounds, including cytosporanthraxanthone, xanthoquinodins A7-A10, ketoxanthoquinodin A6, xanthoquinodins B6-B8, and spiroxanthoquinodins A and B, and one synthetically known compound, 2-methoxy pinselin, as well as ten known compounds, including xanthoquinodins A4-A6, B4, and B5, chrysophanol, physcion, (4S)-5-hydroxy-4-methoxy-α-tetralone, (4S)-4,8-dihydroxy-α-tetralone (or isosclerone), and gonytolide C were isolated from the fungus Cytospora eugeniae BCC42696. Their chemical structures were determined based on the analysis of NMR spectroscopic and mass spectrometric data. Moreover, the absolute configurations of the unknown compounds were established by using NOESY and NOEDIFF NMR experiments along with CD spectroscopic data. The isolated xanthoquinodins exhibited a broad range of antimalarial, antibacterial, and fungicidal activities as well as cytotoxicity. Xanthoquinodins A6, B4, and B5 showed strong activity to Plasmodium falciparum, K1 strain (IC₅₀ 0.52-0.92 μM) and displayed anti-Bacillus cereus (MIC 1.56 μg/mL). Xanthoquinodin A6 also showed anti-Curvularia lunata (MIC 3.13 μg/mL). In addition, xanthoquinodins A4, A6, B4, and B5 and ketoxanthoquinodin A6 showed cytotoxicity against both cancerous (MCF-7, KB, NCI-H187) and non-cancerous (Vero) cells.

Identification and Quantification of Four Anthraquinones in Rhubarb and its Preparations by Gas Chromatography-Mass Spectrometry

A gas chromatographic-mass spectrometric (GC-MS) method was developed for the determination of four anthraquinones found in rhubarb. Chrysophanol, physcion, aloe-emodin and emodin were confirmed by GC-MS and the possible main cleavage pathways of fragment ions are discussed in this study. Rhubarb is a traditional Chinese medicinal herb which required an effective evaluation method to quantitate the four major active anthraquinone compounds described. The determinations of analytes were accomplished by GC-MS using osthole as an internal standard. MS detection was performed in selected ion monitoring mode to increase the sensitivity. The method was evaluated by a number of validation characteristics (precision, limit of detection, calibration range and recovery). The calibration ranges were all 3.2-30.0 μg/mL. This method was fully validated and showed good performances in terms of recovery (96.9-102.9%) and precision (1.4-2.9%). Finally, the method was applied to the analysis of four anthraquinones in rhubarb and its preparations in the first time.

Antibacterial screening of Rumex species native to the Carpathian Basin and bioactivity-guided isolation of compounds from Rumex aquaticus

Plants belonging to the genus Rumex (family Polygonaceae) are used worldwide in traditional medicine for the treatment of various diseases caused by different microorganisms (e.g. bacteria-related dermatologic conditions, dysentery and enteritis). The present study focused on the antibacterial screening of Rumex species native to the Carpathian Basin, and isolation of compounds from one of the most efficient species, Rumex aquaticus. The antibacterial effects of n-hexane, chloroform and aqueous fractions of methanol extracts prepared from different parts of 14 Rumex species (R. acetosella, R. acetosa, R. alpinus, R. aquaticus, R. conglomeratus, R. crispus, R. hydrolapathum, R. obtusifolius subsp. obtusifolius, R. obtusifolius subsp. subalpinus, R. patientia, R. pulcher, R. scutatus, R. stenophyllus and R. thyrsiflorus) were investigated against Staphylococcus epidermidis, S. aureus, MRSA, Bacillus subtilis, Moraxella catarrhalis, Streptococcus pyogenes, S. pneumoniae, S. agalactiae, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae using the disc diffusion method. Mainly the n-hexane and chloroform extracts prepared from the roots of the plants displayed high antibacterial activity (inhibition zones>15mm) against one or more bacterial strains. The highly active extracts of the aerial part and root of R. aquaticus were subjected to a multistep separation procedure. 19 Compounds, among them naphthalenes (musizin, and its glucoside, torachrysone-glucoside, 2-methoxystypandrone), anthraquinones (emodin, chrysophanol, physcion, citreorosein, chrysophanol-8-O-glucoside), flavonoids (quercetin, quercetin-3,3'-dimethylether, isokaempferide, quercetin 3-O-arabinoside, quercetin 3-O-galactoside, catechin), stilbenes (resveratrol, piceid), and 1-stearoylglycerol were isolated from the plant. The antibacterial activities of isolated compounds were determined, and it was observed that especially naphthalenes exerted remarkable antibacterial effects against several bacterial strains.

The Hair Growth-Promoting Effect of Rumex japonicus Houtt. Extract

Rumex japonicus Houtt. is traditionally used as a medicinal plant to treat patients suffering from skin disease in Korea. However, the beneficial effect of Rumex japonicus Houtt. on hair growth has not been thoroughly examined. Therefore, the present study aims to investigate the hair growth-promoting effect of Rumex japonicus (RJ) Houtt. root extract using human dermal papilla cells (DPCs), HaCaT cells, and C57BL/6 mice model. RJ induced antiapoptotic and proliferative effects on DPCs and HaCaT cells by increasing Bcl-2/Bax ratio and activating cellular proliferation-related proteins, ERK and Akt. RJ also increased β-catenin via the inhibition of GSK-3β. In C57BL/6 mice model, RJ promoted the anagen induction and maintained its period. Immunohistochemistry analysis demonstrated that RJ upregulated Ki-67 and β-catenin expressions, suggesting that the hair growth effect of RJ may be mediated through the reinforcement of hair cell proliferation. These results provided important insights for the possible mechanism of action of RJ and its potential as therapeutic agent to promote hair growth.

Microwave-assisted ionic liquid homogeneous liquid-liquid microextraction coupled with high performance liquid chromatography for the determination of anthraquinones in Rheum palmatum L

The microwave-assisted ionic liquid homogeneous liquid-liquid microextraction (MA-IL-HLLME) coupled with high performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of anthraquinones, including aloe-emodin, emodin, chrysophanol and physcion in root of Rheum palmatum L. Several experimental parameters influencing the extraction efficiency, including amount of sample, type and volume of ionic liquid, volume and pH value of extraction medium, microwave power and extraction time, concentration of NH4PF6 as well as centrifugal condition were optimized. When 140μL of ionic liquid ([C8MIM][BF4]) was used as an extraction solvent, target analytes can be extracted from sample matrix in one minute with the help of microwave irradiation. The MA-IL-HLLME is simple and quick. The calibration curves exhibited good linear relationship (r>0.9984). The limits of detection and quantification were in the range of 0.015-0.026 and 0.051-0.088μgmL(-1), respectively. The spiked recovery for each analyte was in the range of 81.13-93.07% with relative standard deviations lower than 6.89%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with ultrasonic and heat reflux extraction. The results indicated that the present method can be successfully applied to the determination of anthraquinones in medicinal plant.

The Genus Rumex: Review of traditional uses, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

The approximately 200 species of the genus Rumex (sorrel, Polygonaceae) are distributed worldwide (European, Asian, African and American countries). Some species have been used traditionally as vegetables and for their medicinal properties. Based on the traditional knowledge, different phytochemical and pharmacological activities have been at the focus of research. This review aims to provide an overview of the current state of knowledge of local and traditional medical uses, chemical constituents, pharmacological activities, toxicity, and safety of Rumex species, in order to identify the therapeutic potential of Rumex species and further directions of research.

MATERIALS AND METHODS

The selection of relevant data was made through a search using the keyword "Rumex" in "Scopus", "Google Scholar", "Web of Science", "PubMed", and "ScienceDirect" databases. Plant taxonomy was validated by the databases "The Plant List", and "Mansfeld's Encyclopedia". Additional information on traditional use and botany was obtained from published books and MSc dissertations.

RESULTS

This review discusses the current knowledge of the chemistry, the in vitro and in vivo pharmacological studies carried out on the extracts, and the main active constituents, isolated from plants of genus Rumex. Although, there are about 200 species in this genus, most of the phytochemical and pharmacological studies were performed on up to 50 species. The aerial parts, leaves and roots of the plants are used as vegetables and for the treatment of several health disorders such as mild diabetes, constipation, infections, diarrhoea, oedema, jaundice, and as an antihypertensive, diuretic and analgesic and in case of skin, liver and gallbladder disorders, and inflammation. Many phytochemical investigations on this genus confirmed that Rumex species are rich in anthraquinones, naphthalenes, flavonoids, stilbenoids, triterpenes, carotenoids, and phenolic acids. Moreover, it draws the attention that high level of oxalic acid in some species can cause toxicity (kidney stones) if consumed large quantity.

CONCLUSIONS

This review confirms that some Rumex species have emerged as a good source of the traditional medicine for treatment of inflammation, cancer and different bacterial infections and provides new insights for further promising investigations on isolated compounds, especially quercetin 3-O-glucoside, emodin, nepodin, torachrysone, and trans-resveratrol to find novel therapeutics and aid drug discovery. In addition, hepatoprotective, antiviral and antidiabetic activities should have priority in future pharmacological studies. However, for applying species to prevent or treat various diseases, additional pharmacological studies are needed to find the mechanism of actions, safety and efficacy of them before starting clinical trials.

Simultaneous separation of three isomeric sennosides from senna leaf (Cassia acutifolia) using counter-current chromatography

Senna leaf is widely consumed as tea to treat constipation or to aid in weight loss. Sennoside A, A1 , and B are dirheinanthrone glucosides that are abundant and the bioactive constituents in the plant. They are isomers that refer to the (R*R*), (S*S*), and (R*S*) forms of protons on C-10 and C-10' centers and it is difficult to refine them individually due to their structural similarities. The new separation method using counter-current chromatography successfully purified sennoside A, A1 , and B from senna leaf (Cassia acutifolia) while reversed-phase medium-pressure liquid chromatography yielded sennoside A only. n-Butanol/isopropanol/water (5:1:6, v/v/v) was selected as the solvent system for counter-current chromatography operation, and the partition coefficients were carefully determined by adding different concentrations of formic acid. High-resolution mass spectrometry and NMR spectroscopy were performed to verify the chemical properties of the compounds.

Biosynthesis of stable iron oxide nanoparticles in aqueous extracts of Hordeum vulgare and Rumex acetosa plants

We report the synthesis and characterization of amorphous iron oxide nanoparticles from iron salts in aqueous extracts of monocotyledonous (Hordeum vulgare) and dicotyledonous (Rumex acetosa) plants. The nanoparticles were characterized by TEM, absorbance spectroscopy, SAED, EELS, XPS, and DLS methods and were shown to contain mainly iron oxide and iron oxohydroxide. H. vulgare extracts produced amorphous iron oxide nanoparticles with diameters of up to 30 nm. These iron nanoparticles are intrinsically unstable and prone to aggregation; however, we rendered them stable in the long term by addition of 40 mM citrate buffer pH 3.0. In contrast, amorphous iron oxide nanoparticles (diameters of 10-40 nm) produced using R. acetosa extracts are highly stable. The total protein content and antioxidant capacity are similar for both extracts, but pH values differ (H. vulgare pH 5.8 vs R. acetosa pH 3.7). We suggest that the presence of organic acids (such oxalic or citric acids) plays an important role in the stabilization of iron nanoparticles, and that plants containing such constituents may be more efficacious for the green synthesis of iron nanoparticles.

New cytotoxic cycloartane triterpene from Cassia italica aerial parts

Phytochemical study of the aerial parts of Cassiaitalica Mill. (family: Fabaceae) growing in Saudi Arabia afforded one new cycloartane triterpene, named (22E)-3-β-hydroxycycloart-22-en-24-one (2), together with eight known compounds: β-sitosterol (1), uvaol (3), daucosterol (4), methyl 3,4-dihydroxybenzoate (5), emodin (6), 4-hydroxypheny-O-β-D-glucopyranoside (7), aloin (8) and rutin (9). The structure of the isolated compounds was determined by physical, chemical and spectral data (UV, IR, MS, 1D ((1)H, (13)C and DEPT) and 2D ((1)H-(1)H COSY, HSQC and HMBC) NMR), as well as by comparing with authentic samples. Compounds 3-5 and 7-9 were isolated for the first time from the plant. Compound 2 was evaluated for its cytotoxic activity against the L5178Y and PC12 cell lines. The total methanolic extract and compounds 5-9 exhibited free radical-scavenging activity using DPPH assay.

Pancreatic Lipase Inhibitory Activity of Cassiamin A, a Bianthraquinone from Cassia siamea

In continuation towards the discovery of potential antiobesity lead(s) from natural products, we have screened n-hexane, dichloromethane (DCM), ethyl acetate (EtOAc) and methanol (MeOH) extracts of 33 Indian medicinal plants (200 extracts) for in vitro pancreatic lipase inhibitory activity. Of the screened extracts, the EtOAc extract of Cassia siamea roots showed 74.3±1.4% enzyme inhibition at 250 μg/mL concentration. Bioassay guided fractionation of the active extract afforded 6 known compounds viz. chrysophanol (1), physcion (2), emodin (3), cassiamin A (4), friedelin (5) and cycloart-25-en-3β,24-diol (6). These compounds were further evaluated for pancreatic lipase inhibitory activity. Cassiamin A (4), a bianthraquinone, was found to be most active with an IC50 value of 41.8±1.2 μM and compounds 2 and 5 were found to be moderate enzyme inhibitors. Results indicate the antiobesity potential of C. siamea through pancreatic lipase inhibition.

Preparative isolation and purification of three sesquiterpenoid lactones from Eupatorium lindleyanum DC. by high-speed counter-current chromatography

A high-speed counter-current chromatography (HSCCC) method was established for the preparative separation of three sesquiterpenoid lactones from Eupatorium lindleyanum DC. The two-phase solvent system composed of n-hexane–ethyl acetate–methanol–water (1:4:2:3, v/v/v/v) was selected. From 540 mg of the n-butanol fraction of Eupatorium lindleyanum DC., 10.8 mg of 3β-hydroxy-8β-[4'-hydroxy-tigloyloxy]-costunolide, 17.9 mg of eupalinolide A and 19.3 mg of eupalinolide B were obtained in a one-step HSCCC separation, with purities of 91.8%, 97.9% and 97.1%, respectively, as determined by HPLC. Their structures were further identified by ESI-MS and ¹H-NMR.

Preparative isolation and purification of four compounds from Cistanches deserticola Y.C. Ma by high-speed counter-current chromatography

Following a constituent enrichment step on a silica gel column, four phenyl-ethanoid glycosides were successfully isolated from Cistanches deserticola and purified by preparative high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of ethyl acetate-n-butanol-ethanol-water (40:6:6:50, v/v/v/v). A total of 30.9 mg acteoside, 13.0 mg isoacteoside, 12.5 mg syringalide A 3'-α-L-rhamnopyranoside and 7.2 mg 2'-acetylacteoside with purity of higher than 95%, as determined by HPLC-ELSD, were obtained in one-step separation from 297 mg of Cistanche deserticola extract, respectively. Their structures were identified by HR-MS, ¹H-NMR and ¹³C-NMR.

Isolation and structural elucidation of indole alkaloids from Geissospermum vellosii by mass spectrometry

Alkaloids from the stem bark of Geissospermum vellosii possess a variety of therapeutic properties including antimalarial activities, activity as a sexual stimulant and inhibition of the proliferation of HIV and herpes viruses. Methods currently used to isolate the active components from G. vellosii are time-consuming, labor intensive, and result in low recovery. In addition, there is a lack of sensitive and accurate analytical methods for the structural characterization and identification of alkaloid components in minor quantities. A combination of high performance counter-current chromatography and ESI tandem mass spectrometry (MS(n)) was established to isolate alkaloids from the stem bark of G. vellosii, and study their electrospray ionization mass spectrometry fragmentation behavior. Five indole alkaloids were successfully isolated and identified by nuclear magnetic resonance and mass spectrometry. The multi-stage tandem mass spectrometric data were used to study their fragmentation pattern and set a model for detailed structure characterization of related indole alkaloids. The presence of the even mass fragment ion suggestive of an odd number of nitrogen at m/z 144 corresponding to C(10)H(9)N was characteristic to indole alkaloids. The results of the experiments demonstrated that the combination of high performance counter current chromatography and ESI-MS(n) is a sensitive, selective and effective approach for rapid isolation and characterization of alkaloids from G. vellosii.

Anticancer activities of six selected natural compounds of some Cameroonian medicinal plants

BACKGROUND

Natural products are well recognized as sources of drugs in several human ailments. In the present work, we carried out a preliminary screening of six natural compounds, xanthone V(1) (1); 2-acetylfuro-1,4-naphthoquinone (2); physcion (3); bisvismiaquinone (4); vismiaquinone (5); 1,8-dihydroxy-3-geranyloxy-6-methylanthraquinone (6) against MiaPaCa-2 pancreatic and CCRF-CEM leukemia cells and their multidrug-resistant subline, CEM/ADR5000. Compounds 1 and 2 were then tested in several other cancer cells and their possible mode of action were investigated.

METHODOLOGY/FINDINGS

The tested compounds were previously isolated from the Cameroonian medicinal plants Vismia laurentii (1, 3, 4, 5 and 6) and Newbouldia laevis (2). The preliminary cytotoxicity results allowed the selection of xanthone V(1) and 2-acetylfuro-1,4-naphthoquinone, which were then tested on a panel of cancer cell lines. The study was also extended to the analysis of cell cycle distribution, apoptosis induction, caspase 3/7 activation and the anti-angiogenic properties of xanthone V(1) and 2-acetylfuro-1,4-naphthoquinone. IC(50) values around or below 4 µg/ml were obtained on 64.29% and 78.57% of the tested cancer cell lines for xanthone V(1) and 2-acetylfuro-1,4-naphthoquinone, respectively. The most sensitive cell lines (IC(50)<1 µg/ml) were breast MCF-7 (to xanthone V(1)), cervix HeLa and Caski (to xanthone V(1) and 2-acetylfuro-1,4-naphthoquinone), leukemia PF-382 and melanoma colo-38 (to 2-acetylfuro-1,4-naphthoquinone). The two compounds showed respectively, 65.8% and 59.6% inhibition of the growth of blood capillaries on the chorioallantoic membrane of quail eggs in the anti-angiogenic assay. Upon treatment with two fold IC(50) and after 72 h, the two compounds induced cell cycle arrest in S-phase, and also significant apoptosis in CCRF-CEM leukemia cells. Caspase 3/7 was activated by xanthone V(1).

CONCLUSIONS/SIGNIFICANCE

The overall results of the present study provided evidence for the cytotoxicity of compounds xanthone V(1) and 2-acetylfuro-1,4-naphthoquinone, and bring supportive data for future investigations that will lead to their use in cancer therapy.