Towards environmentally-friendly solutions for real textile-dyeing wastewater with energy recovery: Effluent recirculation and Rubia plant-derived purpurin electron mediator in microbial fuel cell.

Escalating global water pollution exacerbated by textile-dyeing wastewater (TDW) poses significant environmental and health concerns due to the insufficient treatment methods being utilized. Thus, it is imperative to implement more effective treatment solutions to address such issues. In this research, different environmentally-friendly strategies involving effluent recirculation (ER) and Rubia cordifolia plant-derived purpurin electron mediator (EM) were introduced to enhance the treatment of real TDW and bioelectricity generation performance of an anti-gravity flow microbial fuel cell (AGF-MFC). The results revealed that optimum performance was achieved with a combination of hydraulic retention time (HRT) of 48 h with a recirculation ratio of 1, where the reduction efficiency of biochemical oxygen demand (BOD5), chemical oxygen demand (COD), ammonium (NH4+), nitrate (NO3-), sulphate (SO42-), ammonia nitrogen (NH3-N), colour and turbidity were 82.17 %, 82.15 %, 85.10 %, 80.52 %, 75.91 %, 59.52 %, 71.02 % and 93.10 %, respectively. In terms of bioelectricity generation performance, AGF-MFC showed a maximum output voltage and power density of 404.72 mV and 65.16 mW/m2, respectively. Moreover, the results also signified that higher treatment performance of TDW was obtained with natural purpurin from Rubia cordifolia plant than synthetic purpurin as EM. The reduced reactivity of highly stable synthetic purpurin EM for mediating the electron transfer was a contributing factor to the outperformance of plant-derived purpurin. Additionally, detailed electron-mediating mechanisms of purpurin were proposed to unravel the underlying electron transfer pathway involved in AGF-MFC. This research offers insight into the development of more sustainable solutions for managing TDW, and consequently reducing environmental pollution.

[Syntheses and Structure-Activity Relationship Studies of Antitumor Bicyclic Hexapeptide RA-VII Analogues].

A series of antitumor bicyclic hexapeptide RA-VII analogues modified at residue 2, 3, or 6 were prepared by the chemical transformation of the hydroxy, methoxy, or carboxy groups or the aromatic rings of natural peptides RA-II, III, V, VII, and X. Analogues with modified side chains or peptide backbones, which cannot be prepared by the chemical transformation of their natural peptides, and newly isolated peptides from Rubia cordifolia roots were synthesized by using protected cycloisodityrosines prepared by the degradation of bis(thioamide) obtained from RA-VII or the diphenyl ether formation of boronodipeptide under the modified Chan-Lam coupling reaction conditions. Studies of the conformational features of the analogues and the newly isolated peptides and their relationships with cytotoxic activities against the HCT-116, HL-60, KATO-III, KB, L1210, MCF-7, and P-388 cell lines revealed the following: the methoxy group at residue 3 is essential for the potent cytotoxic activity; the methyl group at Ala-2 and Ala-4 but not at D-Ala-1 is required to establish the bioactive conformation; the N-methyl group at Tyr-5 is necessary for the peptides to adopt the active conformation preferentially; and the orientation of Tyr-5 and/or Tyr-6 phenyl rings has a significant effect on the cytotoxic activity.

Isolation of anthraquinone derivatives from Rubia cordifolia (Rubiaceae) and their bioactivities against plant pathogenic microorganisms.

BACKGROUND: The discovery of antimicrobial ingredients from natural products could be an effective way to create novel fungicides. Rubia cordifolia L., a traditional Chinese herb, may have antimicrobial effects on plant pathogens according to our previous screening study. RESULTS: Rubia cordifolia L. extracts had moderate inhibitory effects on apple Valsa canker (Valsa mali) and tomato grey mould (Botrytis cinerea) at a concentration of 10 mg mL-1. With the use of bioguided isolation methods, eight compounds (1-8) were obtained, including the new compound 2,2,6-trimethyl-6-(4-methylphenyl)-tetrahydropyrano- 3-ol (7), and seven quinone derivatives. Two compounds, mollugin (1) and 1,3,6-trihydroxy-2-methylanthraquinone (6), were found to exhibit outstanding antifungal activities against V. mali and Phytophthora capsici Leon. The half maximal effective concentration (EC50) of compound 1 and compound 6 against V. mali were 79.08 and 81.78 µg mL-1, respectively, and the EC50 of compound 6 against P. capsici was 4.86 µg mL-1. Compound 1 also showed excellent activity against tobacco mosaic virus (TMV). The inactive, inductive, protective and curative activities against TMV were 84.29%, 83.38%, 86.81%, and 60.02%, respectively, at a concentration of 500 µg mL-1, which were all close to or greater than that of the positive control (100 µg mL-1 chitosan oligosaccharide, COS). CONCLUSION: Mollugin and 1,3,6-trihydroxy-2-methylanthraquinone are potentially valuable active compounds that lay a foundation for research on botanical fungicide products derived from R. cordifolia L. and provide lead structures for quinone derivative synthesis and structural modification. © 2024 Society of Chemical Industry.

Chemical constituents of Rubia tibetica Hook. f. from Tibetan medicine and cytotoxic activity evaluation.

Two unprecedented quinone compounds Rubiaxylm A (1) and Rubiaxylm B (2), along with fifteen known anthraquinones (3-17) were isolated and characterized from the roots of Rubia tibetica in Tibetan medicine. Their structures were identified through comprehensive analyses of 1D/2D NMR as well as HR-ESIMS data. Furthermore, all separated compounds were evaluated for their cytotoxic activity on A549, Caco-2, MDA-MB-231 and Skov-3 cell lines. In particular, compound 2 effectively inhibited MDA-MB-231 cells with an IC50 value of 8.15 ± 0.20 µM. Subsequently, the anti-tumor mechanism of 2 was investigated by flow cytometry, JC-1 staining, cell scratching and cell colony. These results indicated that compound 2 could inhibit the proliferation of MDA-MB-231 cells by arresting cells in the G1 phase.

A prenyltransferase participates in the biosynthesis of anthraquinones in Rubia cordifolia.

Anthraquinones (AQs) constitute the largest group of natural quinones, which are used as safe natural dyes and have many pharmaceutical applications. In plants, AQs are biosynthesized through two main routes: the polyketide pathway and the shikimate pathway. The latter primarily forms alizarin-type AQs, and the prenylation of 1,4-dihydroxy-2-naphthoic acid (DHNA) is the first pathway-specific step. However, the prenyltransferase (PT) responsible for this key step remains uncharacterized. In this study, the cell suspension culture of Madder (Rubia cordifolia), a plant rich in alizarin-type AQs, was discovered to be capable of prenylating DHNA to form 2-carboxyl-3-prenyl-1,4-naphthoquinone and 3-prenyl-1,4-naphthoquinone. Then, a candidate gene belonging to the UbiA superfamily, R. cordifoliadimethylallyltransferase 1 (RcDT1), was shown to account for the prenylation activity. Substrate specificity studies revealed that the recombinant RcDT1 recognized naphthoic acids primarily, followed by 4-hydroxyl benzoic acids. The prenylation activity was strongly inhibited by 1,2- and 1,4-dihydroxynaphthalene. RcDT1 RNA interference significantly reduced the AQs content in R. cordifolia callus cultures, demonstrating that RcDT1 is required for alizarin-type AQs biosynthesis. The plastid localization and root-specific expression further confirmed the participation of RcDT1 in anthraquinone biosynthesis. The phylogenetic analyses of RcDT1 and functional validation of its rubiaceous homologs indicated that DHNA-prenylation activity evolved convergently in Rubiaceae via recruitment from the ubiquinone biosynthetic pathway. Our results demonstrate that RcDT1 catalyzes the first pathway-specific step of alizarin-type AQs biosynthesis in R. cordifolia. These findings will have profound implications for understanding the biosynthetic process of the anthraquinone ring derived from the shikimate pathway.

Chemical constituents from the aerial parts of Rubia cordifolia L. with their NO inhibitory activity.

A new naphthoquinone derivative (1) together with twenty-three known compounds (2-24), were isolated from the aerial parts of Rubia cordifolia L. Their structures were elucidated on the basis of NMR and HR-ESIMS data. Compounds 1-13 were assessed for their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophage cells. Compounds 2-6 exhibited significant inhibitory activities with IC50 values of 21.37, 13.81, 24.56, 20.32, and 30.08 µmol·L-1, respectively.

Auxin-dependent regulation of growth via rolB-induced modulation of the ROS metabolism in the long-term cultivated pRiA4-transformed Rubiacordifolia L. calli.

Gene transfer from Agrobacterium to plants is the best studied example of horizontal gene transfer (HGT) between prokaryotes and eukaryotes. The rol genes of A. rhizogenes (Rhizobium rhizogenes) provide uncontrolled root growth, or "hairy root" syndrome, the main diagnostic feature. In the present study, we investigated the stable pRiA4-transformed callus culture of Rubia cordifolia L. While untransformed callus cultures need PGRs (plant growth regulators) as an obligatory supplement, pRiA4 calli is able to achieve long-term PGR-free cultivation. For the first time, we described the pRiA4-transformed callus cultures' PGR-dependent ROS status, growth, and specialized metabolism. As we have shown, expression of the rolA and rolB but not the rolC genes is contradictory in a PGR-dependent manner. Moreover, a PGR-free pRiA4 transformed cell line is characterised as more anthraquinone (AQ) productive than an untransformed cell culture. These findings pertain to actual plant biotechnology: it could be the solution to troubles in choosing the best PGR combination for the cultivation of some rare, medicinal, and woody plants; wild-type Ri-plants and tissue cultures may become freed from legal controls on genetically modified organisms in the future. We propose possible PGR-dependent relationships between rolA and rolB as well as ROS signalling targets. The present study highlighted the high importance of the rolA gene in the regulation of combined rol gene effects and the large knowledge gap in rolA action.

TLC-MS-Bioautographic Identification of Antityrosinase Compounds and Preparation of a Topical Gel Formulation from a Bioactive Fraction of an RSM-Optimized Alcoholic Extract of Rubia Cordifolia L. stem.

BACKGROUND: Rubia cordifolia L., Rubiaceae, is globally reported to treat skin-related problems. The study aimed to assess the antityrosinase potential of Rubia cordifolia (ARC) and the development of gel formulation. METHODS: The AutoDock Vina (version V.1.2.0) program package was used for molecular docking to check for the binding affinity of ligands with protein. Response surface methodology (RSM) software was used to optimize extraction parameters for an alcoholic extract of Rubia cordifolia (ARC). The developed HPTLC method for the quantification of purpurin in ARC was validated as per the International Conference on Harmonization (ICH) guidelines. A bioautographic study for the evaluation of antityrosinase effects was performed; an anthraquinone-enriched fraction (AEF)-loaded gel formulation developed and evaluated physicochemically which could be used to reduce skin pigmentation. RESULTS: Purpurin showed optimum binding affinity (-7.4 kcal/mol) with the molecular target (tyrosinase) when compared to that of standard kojic acid (-5.3 kcal/mol). Quantification of purpurin in ARC, optimized by RSM software, was validated and physiologically significant results were observed for the antityrosinase potential of an AEF, along with TLC-MS-bioautographic identification for antityrosinase compounds: purpurin (m/z 256.21) and ellagic acid (m/z 302.19). Evaluation of an AEF-loaded gel formulation by in vitro and ex vivo permeation studies was performed. CONCLUSION: ARC extraction parameters optimized by RSM, and a bioautographic study helped identify antityrosinase compounds. The development of a gel formulation could be a cost-effective option for the treatment of depigmentation in the future. HIGHLIGHTS: A TLC-MS-Bioautography-based Identification of Antityrosinase Compounds and development of AEF-loaded Topical Gel formulation from a Bioactive Fraction of an RSM-Optimized Alcoholic Extract of Rubia Cordifolia L. stem, which could help with promising results in reducing skin pigmentation and maintaining even tone.

Characterization and antimicrobial evaluation of anthraquinones and triterpenes from Rubia cordifolia.

Chemical investigation of roots of the plant, Rubia cordifolia Linn, led to the isolation of an undescribed anthraquinone, cordifoquinone R, determined as 1,2-dihydroxy-6-methoxyanthracene-9,10-dione (6) based on the 1D and 2D NMR analyses and HRESIMS. Ten other known compounds viz.1,4-dihydroxy-2-methoxyanthracene-9,10-dione (1), rubiadin (2), xanthopurpurin (3), 1-methoxy-3-hydroxy-2-carbomethoxy-9,10-anthraquinone (4), alizarin (5), ß-sitosterol glucoside (7), scopoletin (8), oleanolic acid, (9), pomolic acid (10), queretaroic acid (11) were also isolated. Out of these compounds, 4, 10, and 11 are first reported from this plant species. Compounds 2, 3, 6, 7, and 10 showed activity in the range of 16-32 µg/ml against S. aureus ATCC 29213.

Madder (Rubia cordifolia L.) Alleviates Myocardial Ischemia-Reperfusion Injury by Protecting Endothelial Cells from Apoptosis and Inflammation.

Objective: Ischemia-reperfusion injury often occurs in organ transplantation, coronary heart disease, ischemic heart disease, and other diseases, which greatly reduces clinical efficacy. This study examined the effectiveness of madder as a medicine to treat ischemia-reperfusion injury. Methods: The efficacy of madder was evaluated by measuring myocardial infarction size, coronary outflow volume, myocardial contraction rate, activation of inflammatory factors, autophagy factors, apoptosis factors, and related pathway genes in mice. Results: The results indicated that treatment with madder can effectively reduce the area of myocardial infarction and restore arterial blood flow velocity and myocardial contractility in mice. Additionally, madder treatment inhibited the expression of inflammatory factors, autophagy factors, and apoptosis factors in mice and reduced the degree of myocardial cell injury. Studies have also shown that madder treatment can alleviate myocardial ischemia-reperfusion injury in mice and inhibit the occurrence of inflammatory response by inhibiting the activity of the NF-κB pathway. Conclusion: The results showed that madder was effective against ischemia-reperfusion injury, thus showing potential as a clinical drug for treating ischemia-reperfusion injury.

The Underling Mechanisms Exploration of Rubia cordifolia L. Extract Against Rheumatoid Arthritis by Integrating Network Pharmacology and Metabolomics.

Purpose: Rubia cordifolia L. (RC) is a classic herbal medicine for the treatment of rheumatoid arthritis (RA) and has been used since ancient times. The ethanol extract of Rubia cordifolia L. (RCE) showed obvious anti-RA effects in our previous study. However, further potential mechanisms require more exploration. We aimed to investigate the mechanism of RCE for the treatment of RA by integrating metabolomics and network pharmacology in this study. Methods: An adjuvant-induced arthritis (AIA) rat model was established, and we evaluated the therapeutic effects of RCE. Metabolomics of serum and urine was used to identify the differential metabolites. Network pharmacology was applied to determine the key metabolites and potential targets. Finally, the potential targets and compounds of RCE were verified by molecular docking. Results: The results indicated that RCE suppressed foot swelling and alleviated joint damage and also had anti-inflammatory properties by inhibiting the expressions of tumor necrosis factor (TNF)-α, Interleukin (IL)-1ß, prostaglandin E2 (PGE2), and P65. Ten and seven differential metabolites were found in the serum and urine, respectively, of rats. Six key targets, ie, phospholipase A2 group IIA (PLA2G2A), phospholipase A2 group X (PLA2G10), cytidine deaminase (CDA), uridine-cytidine kinase 2 (UCK2), charcot-leyden crystal galectin (CLC), and 5',3'-nucleotidase, mitochondrial (NT5M), were discovered by network pharmacology and metabolite analysis and were found to be related to glycerophospholipid metabolism and pyrimidine metabolism. Molecular docking confirmed that the favorable compounds showed affinities with the key targets, including alizarin, 6-hydroxyrubiadin, ruberythric acid, and munjistin. Conclusion: This study revealed the underlying mechanisms of RCE and provided evidence that will allow researchers to further investigate the functions and components of RCE against RA.

An eco-friendly method of extracting alizarin from Rubia tinctorum roots under supercritical carbon dioxide and its application to wool dyeing.

Because of its low critical temperature and pressure levels, supercritical carbon dioxide (scCO2) is the most widely used supercritical fluid in the supercritical fluid extraction (SFE) technique. Alizarin was extracted from madder roots (Rubia tinctorum) using scCO2 under different conditions of co-solvent ratio (0-50%), temperature (45-95 °C), pressure (150-250 bar), extraction time (15-120 min), and flow rate (5-9 mL/min). Based on alizarin recovery and minimization of environmental risk, the optimum conditions were determined. SFE was optimum at 90% CO2:10% methanol (Me), 65 °C, 250 bar, 45 min, and 9 mL/min. The alizarin recovery, and its content in R. tinctorum extract (RE) under the optimum conditions were 1.34 g/kg roots, and 6.42%, respectively. Using conventional dyeing methods, wool fabrics were dyed with RE at different concentrations (2-6%). Various types of mordants were also used in the dyeing process, including chemical and bio-mordants. Color and fastness properties of dyed wool fabrics were evaluated based on RE concentration and mordant type. A higher RE concentration and the use of mordants, specifically Punica granatum (P. granatum) peels, increased the color characteristics. RE and dyed fabrics exhibited good antibacterial activity against the tested bacterial strains, especially Pseudomonas aeruginosa and Escherichia coli.

Biosynthesis of copper oxide nanoparticles using Rubia cordifolia bark extract: characterization, antibacterial, antioxidant, larvicidal and photocatalytic activities.

Rubia cordifolia represents the pivotal plant resource belonging to traditional Chinese medicine and Indian Ayurveda. The present study aims to synthesize biocompatible copper oxide nanoparticles (CuONPs) using R. cordifolia bark extracts, characterize the incumbent chemical transitions, and explore their biomedical and environmental applications. The absorbance peak between 250 and 300 nm clearly demonstrates the formation of CuONPs in the UV-visible spectrum. Fourier transform infrared spectroscopy results showed the presence of functional groups essential for copper ion reduction. Field emission scanning electron microscopy (FE-SEM) and dynamic light scattering analysis revealed that the CuONPs are spherical-shaped with a mean particle size of 50.72 nm. Additionally, the zeta potential demonstrates its robustness at 11.2 mV. X-ray diffraction pattern showed mixed phases (Cu, Cu2O, and CuO) of cubic monoclinic crystalline nature. CuONPs exhibited noticeable antibacterial activity against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus cereus) pathogenic bacteria. Bacterial cell damages were affirmed through FE-SEM imaging when treated with CuONPs. Further, CuONPs demonstrated considerable antioxidant activities by quenching free radicals such as DPPH (60.75%), ABTs (70.88%), nitric oxide (65.48%) and reducing power (71.44%) in a dose-dependent way. CuONPs showed significant larvicidal activity against Aedes aegypti (65 ± 8.66%), Anopheles stephensi (80 ± 13.69%), and Culex quinquefasciatus (72 ± 13.04%) mosquito larvae. The photocatalytic activity of the CuONPs demonstrates the methylene blue (81.84%) and crystal violet (64.0%) dye degradation potentials, indicating the environmental bioremediation efficacy. Hence the present study is the first report in accounting for the versatile applications of the phyto-CuONPs. Moreover, the green synthesis of CuONPS has future applications in designing the drug for life-threatening diseases and various environmental issues.

Research Note: Effect of Rubia cordifolia L. processed Terminalia chebula Retz polysaccharide on the histological structure and apoptosis in the spleen in immunosuppressed Chinese yellow quail.

It is generally accepted herbal polysaccharide and is a bioactive compound of herbal medicines with immunomodulatory activities. It has a wide range of pharmacological effects. It can be used as a green substitute for antibiotics or as a feed additive in quail breeding. Therefore, the herbal polysaccharide has a broader and safer application prospect. The immunosuppressive disease of quail is one of the most important infectious diseases. It seriously affects the growth, development, and production performance of quail, causing huge economic losses to quail industry. However, there is no report on the effective alleviation of spleen injury in immunosuppressed animals by herbal polysaccharide. Therefore, we established a pathological model of immunosuppressive Chinese yellow quail for the first time, with the Terminalia chebula Retz polysaccharide (TCP) as the control, and histological observation, TUNEL staining were used to study the effects of Rubia cordifolia L. processed Terminalia chebula Retz polysaccharide (RTCP) on splenic tissue structure and apoptosis of immunosuppressed Chinese yellow quail. The experimental results showed that spleen organ index of the cyclophosphamide (CTX) group was significantly lower than these of blank control group, the TCP group and the RTCP group (P < 0.05). And the number of splenic nodules in the CTX group was significantly lower than that in the blank control group (P < 0.01). Compared with the CTX group, the spleen volume of the TCP group and the RTCP group increased, and the number and area of spleen nodules increased. Among them, the spleen nodules in the RTCP group were significantly more higher than that in the CTX group (P < 0.01). Meanwhile, TUNEL staining showed that the TUNEL positive cells in the CTX group were the most significantly higher than those in the blank control group (P < 0.01). TCP group and RTCP group were significantly higher than the blank control group (P < 0.01), but significantly lower than CTX group (P < 0.05). All these results suggested that RTCP could effectively improve CTX-induced spleen damage in immunosuppressed Chinese yellow quails by promoting the recovery of spleen organ index, repairing the spleen tissue structure, and diminishing the apoptosis. Moreover, RTCP is more effective than TCP. The results prove that the efficacy of RTCP in protecting spleen from CTX induced injury was enhanced after processing with Rubia cordifolia L. Therefore, our findings will provide more possibilities to promote the clinical application and development of processed traditional Chinese medicine in the further.

Noninvasive Characterization and Quantification of Anthraquinones in Dyed Woolen Threads by Visible Diffuse Reflectance Spectroscopy.

The anthraquinone components of the roots of various species of madder (like Rubia tinctorum L. and Rubia peregrina L.) have been used for millennia as red colorants in textiles, carpets, tapestries, and other objects. To understand the selection and preparation of dyestuffs in various cultures and historical periods, these dyes (mainly alizarin and purpurin) are traditionally analyzed by means of separation methods that require sampling. This contribution focuses on establishing a fast, noninvasive, and in situ analytical procedure based on visible reflectance spectroscopy for the characterization and quantification of anthraquinones in ancient wool yarns. The method was successfully applied to Coptic textiles, and the analytical results are in agreement with prior observations obtained on samples by separation techniques.

New Potential Pharmacological Targets of Plant-Derived Hydroxyanthraquinones from Rubia spp.

The increased use of polyphenols nowadays poses the need for identification of their new pharmacological targets. Recently, structure similarity-based virtual screening of DrugBank outlined pseudopurpurin, a hydroxyanthraquinone from Rubia cordifolia spp., as similar to gatifloxacin, a synthetic antibacterial agent. This suggested the bacterial DNA gyrase and DNA topoisomerase IV as potential pharmacological targets of pseudopurpurin. In this study, estimation of structural similarity to referent antibacterial agents and molecular docking in the DNA gyrase and DNA topoisomerase IV complexes were performed for a homologous series of four hydroxyanthraquinones. Estimation of shape- and chemical feature-based similarity with (S)-gatifloxacin, a DNA gyrase inhibitor, and (S)-levofloxacin, a DNA topoisomerase IV inhibitor, outlined pseudopurpurin and munjistin as the most similar structures. The docking simulations supported the hypothesis for a plausible antibacterial activity of hydroxyanthraquinones. The predicted docking poses were grouped into 13 binding modes based on spatial similarities in the active site. The simultaneous presence of 1-OH and 3-COOH substituents in the anthraquinone scaffold were emphasized as relevant features for the binding modes' variability and ability of the compounds to strongly bind in the DNA-enzyme complexes. The results reveal new potential pharmacological targets of the studied polyphenols and help in their prioritization as drug candidates and dietary supplements.

Therapeutic potential of biogenic and optimized silver nanoparticles using Rubia cordifolia L. leaf extract.

Rubia cordifolia L. is a widely used traditional medicine in the Indian sub-continent and Eastern Asia. In the present study, the aqueous leaf extract of the R. Cordifolia was used to fabricate silver nanoparticles (RC@AgNPs), following a green synthesis approach. Effect of temperature (60 °C), pH (8), as well the concentration of leaf extract (2 ml) and silver nitrate (2 mM) were optimized for the synthesis of stable RC@AgNPs. The phytofabrication of nanosilver was validated by UV-visible spectral analysis, which displayed a distinctive surface plasmon resonance peak at 432 nm. The effective functional molecules as capping and stabilizing agents, and responsible for the conversion of Ag+ to nanosilver (Ag0) were identified using the FTIR spectra. The spherical RC@AgNPs with an average size of ~ 20.98 nm, crystalline nature, and 61% elemental composition were revealed by TEM, SEM, XRD, and. EDX. Biogenic RC@AgNPs displayed a remarkable anticancer activity against B16F10 (melanoma) and A431 (carcinoma) cell lines with respective IC50 of 36.63 and 54.09 µg/mL, respectively. Besides, RC@AgNPs showed strong antifungal activity against aflatoxigenic Aspergillus flavus, DNA-binding properties, and DPPH and ABTS free radical inhibition. The presented research provides a potential therapeutic agent to be utilized in various biomedical applications.

Identification of meroterpenoids from Bipolaris victoriae S27 and their potential activity against tumor metastasis and inhibition of the NF-κB signaling pathway.

Three undescribed meroterpenoids, named bipolacochlioquinones A-C, together with seven known compounds, were isolated from the plant endophytic fungus Bipolaris victoriae S27 derived from the fresh stems of Rubia podantha Diels. Their structures were mainly determined by extensive spectroscopic analysis. The relative configurations of bipolacochlioquinones A-C were assigned using the ROESY spectrum, comparison of their spectral data with that reported in the literatures, and NMR calculations. Moreover, their complete absolute configurations were further established by electronic circular dichroism calculations using density functional theory. Among them, bipolacochlioquinone A is found to represent the first example of previously undescribed 6/6/6/6/6 pentacyclic dioxane-containing cochlioquinones, and bipolacochlioquinone B possesses a rare 6/6/6/6/5 pentacyclic system bearing a tetrahydrofuran ring fused to a polyketide and a sesquiterpenoid subunit. All compounds were evaluated for their inhibitory effects on tumor growth, metastasis, and the NF-κB signaling pathway. Among them, bipolacochlioquinone C and cochlioquinone A show the most potent cytotoxicities and NF-κB inhibitory activities. The effects of bipolacochlioquinone C and cochlioquinone A on the expression of NF-κB-associated proteins were also evaluated using western blotting. These results indicate that bipolacochlioquinone C and cochlioquinone A can inhibit the growth and metastasis of HCT116 and MDA-MB-231 cells by suppressing the NF-κB signaling pathway.

De Novo Transcriptome Analysis Reveals Putative Genes Involved in Anthraquinone Biosynthesis in Rubia yunnanensis.

Rubia yunnanensis Diels (R. yunnanensis), a Chinese perennial plant, is well-known for its medicinal values such as rheumatism, contusion, and anemia. It is rich in bioactive anthraquinones, but the biosynthetic pathways of anthraquinones in R. yunnanensis remain unknown. To investigate genes involved in anthraquinone biosynthesis in R. yunnanensis, we generated a de novo transcriptome of R. yunnanensis using the Illumina HiSeq 2500 sequencing platform. A total of 636,198 transcripts were obtained, in which 140,078 transcripts were successfully annotated. A differential gene expression analysis identified 15 putative genes involved in anthraquinone biosynthesis. Additionally, the hairy roots of R. yunnanensis were treated with 200 µM Methyl Jasmonate (MeJA). The contents of six bioactive anthraquinones and gene expression levels of 15 putative genes were measured using ultra performance liquid chromatography coupled with mass spectrometry (UPLC-MS/MS) and real-time quantitative polymerase chain reaction (RT-qPCR), respectively. The results showed that the expressions levels for 11 of the 15 genes and the contents of two of six anthraquinones significantly increased by MeJA treatment. Pearson's correlation analyses indicated that the expressions of 4 of the 15 putative genes were positively correlated with the contents of rubiquinone (Q3) and rubiquinone-3-O-ß-d-xylopranosyl-(1→6)-ß-d-glucopyranoside (Q20). This study reported the first de novo transcriptome of R. yunnanensis and shed light on the anthraquinone biosynthesis and genetic information for R. yunnanensis.

Anthraquinones from the Aerial Parts of Rubia cordifolia with Their NO Inhibitory and Antibacterial Activities.

The present study aimed to identify the composition of the aerial parts of Rubia cordifolia L. A chemical investigation on the EtOAc extracts from the aerial parts of Rubia cordifolia resulted in the isolation of four new anthraquinones, namely Cordifoquinone A-D (1-4), along with 16 known anthraquinones. Their structures were elucidated on the basis of NMR and HR-ESIMS data. All isolates were assessed for their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophage cells. Compounds 1, 3 and 10 exhibited significant inhibitory activities with IC50 values of 14.05, 23.48 and 29.23 µmol·L-1, respectively. Their antibacterial activities of four bacteria, Escherichia coli (ATCC 25922), Staphylococcus aureus subsp. aureus (ATCC 29213), Salmonella enterica subsp. enterica (ATCC 14028) and Pseudomonas aeruginosa (ATCC 27853), were also evaluated. Our results indicated that the antibacterial activity of these compounds is inactive.