Investigation of the interaction of anthraquinones of Cassia occidentalis seeds with bovine serum albumin by molecular docking and spectroscopic analysis: Correlation to their in vitro cytotoxic potential

Albumin as an Effective Auxiliary Agent for the Enriched Extraction of Anthraquinones and Curcumin from Plant Matrices

Nowadays, several processes to enrich desired bioactive compounds in plant extracts have been developed. The objective of the present study was to assess the performance of bovine serum albumin in increasing the extractive yields of anthraquinones and diarylheptanoids from their respective raw plant powder extracts. Aloe emodin, rhein, emodin, and chrysophanol, from Polygonum cuspidatum, Senna alexandrina, Rhamnus frangula, and Rheum palmatum, and curcumin from Curcuma longa were analyzed in parent dry extracts, solubilized either with water, ethanol, or hydro-alcoholic mixtures, and in ones treated with aqueous solutions of bovine serum albumin by HPLC with UV/Vis detection. The different ratios between the volumes of solvents, powdered plant extracts, and bovine serum albumin were tested. The addition of albumin provided an increase in the yields of aloe emodin in the range 7.8-50.4-fold; of rhein in the range 6.1-14.1-fold; of emodin in the range 19.7-39.7-fold; of chrysophanol in the range 15.1-28.7-fold; and, finally, of curcumin of 32.1-fold. The addition of bovine serum albumin in the processing of plant extracts has been shown to be a novel and a valid alternative, comparing favourably to already reported methodologies. The easy-to-handle procedures, readily accessible facilities, and the employment of cheap substrates and reagents represent the most evident advantages of the methodology described herein.

Oxidative regulation and cytoprotective effects of γ-polyglutamic acid on surimi sol subjected to freeze-thaw process

Frozen surimi sol incline to protein oxidation, but the quality control strategies based on oxidation remain limited. Hence, the antioxidant and cryoprotective effects of γ-polyglutamic acid (γ-PGA) on freeze-thawed salt-dissolved myofibrillar protein (MP) sol were investigated. Results showed that γ-PGA could effectively regulate protein oxidation of MP sol during freeze-thawing with lower carbonyl contents and less oxidative cross-linking. Meanwhile, γ-PGA primely maintained sol protein structures, showing reduction of 15.28% of salt soluble protein contents at γ-PGA addition of 0.04% under unoxidized condition. Additionally, compared to the control group without oxidation treatment, cooking loss of heat-induced gel with 0.04% γ-PGA decreased by 47.19%, while gel strength obviously increased by 57.22% respectively. Overall, moderate γ-PGA addition (0.04%) could inhibit protein oxidation of sol, further improving frozen stability of sol through hydrogen bonds and hydrophobic interaction, but excessive γ-PGA was adverse to sol quality due to severe cross-linking between γ-PGA and MP.

Isoliquiritigenin as a modulator of the Nrf2 signaling pathway: potential therapeutic implications

Nuclear factor erythroid-2-related factor 2 (Nrf2), a transcription factor responsible for cytoprotection, plays a crucial role in regulating the expression of numerous antioxidant genes, thereby reducing reactive oxygen species (ROS) levels and safeguarding cells against oxidative stress. Extensive research has demonstrated the involvement of Nrf2 in various diseases, prompting the exploration of Nrf2 activation as a potential therapeutic approach for a variety of diseases. Consequently, there has been a surge of interest in investigating the Nrf2 signaling pathway and developing compounds that can modulate its activity. Isoliquiritigenin (ISL) (PubChem CID:638278) exhibits a diverse range of pharmacological activities, including antioxidant, anticancer, and anti-tumor properties. Notably, its robust antioxidant activity has garnered significant attention. Furthermore, ISL has been found to possess therapeutic effects on various diseases, such as diabetes, cardiovascular diseases, kidney diseases, and cancer, through the activation of the Nrf2 pathway. This review aims to evaluate the potential of ISL in modulating the Nrf2 signaling pathway and summarize the role of ISL in diverse diseases prevention and treatment through modulating the Nrf2 signaling pathway.

Quality analysis of steamed beef with black tea and the mechanism of action of main active ingredients of black tea on myofibrillar protein

In this study, we analyzed the tea polyphenol composition, volatile flavor composition and storage stability of steamed beef with black tea. The molecular docking and dynamics were used to elucidate the interaction mechanism between the active components of black tea and myofibrillar proteins. The highest content of caffeine (CAF) was found in black tea steamed beef products, followed by catechin (C), epicatechin gallate (ECG), epicatechin gallate (EGCG) and theaflavins (TF). Steamed beef with black tea showed low ΔE* value, low TBARS value, low carbonyl content as well as high sulfhydryl content during storage. The addition of C, CAF, ECG, EGCG and TF enhanced the oxidative stability of myofibrillar protein. In this study, the effects of active components of black tea on the oxidative stability of myofibrillar protein and their interactions were determined, which could provide a reference for the application of black tea and its active components in meat products. At the same time, it can provide new ideas for the development of new meat products.

Non-covalent binding of chlorogenic acid to myofibrillar protein improved its bio-functionality properties and metabolic fate

As natural antioxidants added to meat products, polyphenols can interact with proteins, and the acid-base environment influenced the extent of non-covalent and covalent interactions between them. This study compared the bio-functional characteristics and metabolic outcomes of the myofibrillar protein-chlorogenic acid (MP-CGA) complexes binding in different environments (pH 6.0 and 8.5). The results showed that CGA bound with MP significantly enhanced its antioxidant activity and inhibitory effect on metabolism enzymes. CGA bound deeply into the MP structure hydrophobic cavity at pH 6.0, which reduced its degradation by digestive enzymes, thus increasing its bio-accessibility from 59.5% to 71.6%. The digestion products of the two complexes exhibited significant differences, with the non-covalent MP-CGA complexes formed at pH 6.0 showing significantly higher concentrations of rhetsinine and piplartine, two well-known compounds to modulate diabetes. This study demonstrated that non-covalent binding between protein and polyphenol in the acidic environment held greater promising prospects for improving health.

Isoliquiritigenin attenuates emodin-induced hepatotoxicity in vivo and in vitro through Nrf2 pathway

Emodin (EMO), the main bioactive component of Polygonum multiflorum, Rheum palmatum, Aloe vera and Cassia acutifolia, can cause severe hepatotoxicity. Isoliquiritigenin (ISL), a flavonoid compound from the Glycyrrhiza, has been reported to be the most potent antioxidant response element (ARE)-luciferase inducer among the main components of licorice. But the protective effect and underlying mechanism of ISL on liver injury induced by EMO has not been reported. This study aims to explore the role of nuclear transcription factor 2 (Nrf2) in EMO-induced hepatotoxicity and the protective effect of ISL. EMO treatment caused cytotoxicity in L-02 cells. Combined treatment of EMO with ISL effectively reversed changes in cell viability, reduced reactive oxygen species (ROS) generation and malondialdehyde (MDA) generation, enhanced the levels of glutathione (GSH) and super oxide dismutase (SOD) induced by EMO in L-02 cells. Furthermore, ISL could also phosphorylate mitogen-activated protein kinases (MAPKs) and up-regulate Kelth-like ECH-associated protein (Keap1). The pathways of MAPKs and Keap1 lead to the separation of Keap1 and Nrf2. Free Nrf2 transferred to the nucleus and enhanced the expression of phase II detoxification enzymes. In conclusion, our results are the first to highlight the beneficial role and relevant mechanisms of ISL in EMO-induced liver injury and provide novel insight into its application.

Alterations in the conformation and function of human serum albumin induced by the binding of methyl hydrogen phthalate

Phthalate esters (PAEs) are widely used as plasticizer components in production. Methyl hydrogen phthalate (MHP) is a metabolite of dimethyl phthalate (DMP, a kind of PAEs), and its toxic residues accumulate in the nature and can enter the human body. Here, the interaction between MHP and human serum albumin (HSA) was probed by using multi-spectral, computer simulations, and biochemical techniques. The results showed that MHP was spontaneously embedded in site I of HSA to form a complex by H-bonds and van der Waals forces (ΔH < 0, ΔS < 0). The binding constant (K_a) of the HSA-MHP system was 1.136 ± 0.026 × 10⁴ M^-1 (298 K). The combination of MHP produced conformational variations of HSA, as shown by the 3D fluorescence spectrum, CD spectra, and molecular dynamics simulation. Additionally, molecular docking indicated that MHP was surrounded by multiple residues, such as Lys199, Leu203, Phe206, and Trp214. Specifically, Lys199 and Trp214 exerted a crucial effect on the interaction of HSA and MHP. The residues with important energy contribution were mostly located in site I. The ASA values of the aromatic amino acids of HSA changed after combining with MHP. The R_g and SASA values of HSA increased after adding MHP, suggesting that the structure of HSA was less compact. Moreover, the esterase-like activity of HSA increased after adding MHP to HSA, indicating that MHP may disturb the normal physiological activities in the human body. This study was helpful to understand the biological function of MHP and provided some insights for its side effect in the human body.

Advances in Understanding the Role of Aloe Emodin and Targeted Drug Delivery Systems in Cancer

Cancer is one of the important causes of death worldwide. Despite remarkable improvements in cancer research in the past few decades, several cancer patients still cannot be cured owing to the development of drug resistance. Natural sources might have prominence as potential drug candidates. Among the several chemical classes of natural products, anthraquinones are characterized by their large structural variety, noticeable biological activity, and low toxicity. Aloe emodin, an anthraquinone derivative, is a natural compound found in the roots and rhizomes of many plants. This compound has proven its antineoplastic, anti-inflammatory, antiangiogenic, and antiproliferative potential as well as ability to prevent cancer metastasis and potential in reversing multidrug resistance of cancer cells. The anticancer property of aloe emodin, a broad-spectrum inhibitory agent of cancer cells, has been detailed in many biological pathways. In cancer cells, these molecular mechanisms consist of inhibition of cell growth and proliferation, cell cycle arrest deterioration, initiation of apoptosis, antimetastasis, and antiangiogenic effect. In accordance with the strategy of developing potential drug candidates from natural products, aloe emodin's low bioavailability has been tried to be overcome by structural modifications and nanocarrier systems. Consequently, this review summarizes the antiproliferative and anticarcinogenic properties of aloe emodin, as well as the enhanced activity of its derivatives and the advantages of drug delivery systems on bioavailability.

Interaction Study between ESIPT Fluorescent Lipophile-Based Benzazoles and BSA

In this study, the interactions of ESIPT fluorescent lipophile-based benzazoles with bovine serum albumin (BSA) were studied and their binding affinity was evaluated. In phosphate-buffered saline (PBS) solution these compounds produce absorption maxima in the UV region and a main fluorescence emission with a large Stokes shift in the blue–green regions due to a proton transfer process in the excited state. The interactions of the benzazoles with BSA were studied using UV-Vis absorption and steady-state fluorescence spectroscopy. The observed spectral quenching of BSA indicates that these compounds could bind to BSA through a strong binding affinity afforded by a static quenching mechanism (K_q~10¹² L·mol⁻¹·s⁻¹). The docking simulations indicate that compounds 13 and 16 bind closely to Trp134 in domain I, adopting similar binding poses and interactions. On the other hand, compounds 12, 14, 15, and 17 were bound between domains I and III and did not directly interact with Trp134.

Structural and functional modifications of myofibrillar protein by natural phenolic compounds and their application in pork meatball

Effects of different phenolic compounds on the structural and functional properties of myofibrillar protein (MP) were investigated, and the phenolic compounds were applied as natural modifiers in pork meatball. Interactions between MP and phenolic compounds were determined via molecular docking to elucidate the modification mechanisms. Tannic acid, gallic acid, (-)-epigallocatechin gallate, and epigallocatechin interacted with MP primarily through hydrogen bonds, which unfolded the secondary structures of MP and lowered surface hydrophobicity. Accordingly, the solubility, gel properties, and oxidation stability of MP were improved, while the emulsifying properties significantly decreased. Quercetin and quercitrin showed electrostatic interactions with MP, which preserved α-helix structures and increased surface hydrophobicity. While, the modifications lent MP the enhanced emulsifying properties, thermal stability, and oxidation stability, but the gel properties and solubility were mitigated. In addition, the incorporation of phenolic compounds prevented MP oxidation based upon their antioxidant abilities deriving from hydroxyl groups. Once the phenolic compounds were used in pork meatball, a minced meat model, they significantly improved the quality of meatball by bettering the texture properties and controlling the oxidation level. The results suggest that phenolic compounds have great potential to be employed as natural additives in minced meat products for the modification of functional properties.

Comprehensive insights into the interactions of dicyclohexyl phthalate and its metabolite to human serum albumin

Phthalate esters (PAEs) are a type of persistent organic pollutants and have received widespread concerns due to their adverse effects on human health. Dicyclohexyl phthalate (DCHP) and its metabolite monocyclohexyl phthalate (MCHP) were selected to explore the mechanism for interaction of PAEs with human serum albumin (HSA) through molecular docking and several spectroscopic techniques. The results showed that DCHP/MCHP can spontaneously occupy site I to form a binary complex with HSA, and DCHP exhibited higher binding affinity to HSA than MCHP. At 298 K, the binding constants (K_b) of DCHP and MCHP to HSA were 24.82 × 10⁴ and 1.04 × 10⁴ M^-1, respectively. Hydrogen bonds and van der Waals forces were the major driving forces in DCHP/MCHP-HSA complex. The presence of DCHP/MCHP induced the secondary structure changes in HSA, and the pi electrons of the benzene ring skeleton of DCHP/MCHP played a key role in this binding processes. Exposure of DCHP/MCHP to TM4 cells revealed that interactions between PAEs and serum albumin can affect their cytotoxicity; DCHP showed higher toxicity than MCHP. The binding affinity of PAEs with HSA may be a valuable parameter for rapid assessment of their toxicity to organisms.

Role of anthraquinones in Cassia occidentalis induced hepato-myo-encephalopathy

ETHNOPHARMACOLOGICAL RELEVANCE

The different plant parts of Cassia occidentalis Linn, (CO) such as root, leaves, seeds and pods have traditionally been used in multifarious medicines for the treatment of dysentery, diarrhea, constipation, fever, eczema, cancer and venereal diseases.

MATERIALS AND METHODS

A systematic search of literature has been done in books and scientific databases like Science Direct, Pubmed, Google Scholar and Scopus etc. These sources were used to compile, analyze and review the information regarding the phytochemistry, toxicology and mechanism of toxicity of CO. The various references on this subject are cited in our review ranging from 1956 to 2019.

RESULTS

Unintentional exposure of CO causes serious pathological condition in children, known as hepato-myo-encephalopathy (HME). The toxicity after CO consumption is associated with the presence of anthraquinones (AQs), a class of secondary plant metabolites. These AQs at high concentrations are known to cause detrimental effects on essential vital organs such as liver, kidney, spleen, brain, muscle and reproductive organs. The animal studies in rodent models as well as clinical investigations have clearly revealed that CO toxicity is associated with enhanced hepatotoxicity serum markers (ALT, AST, and LDH) and presence of necrotic lesions in liver. Furthermore, CO also causes vacuolization in muscle tissue and increases the level of CPK which is a prominent muscle damage marker. Apart from these target organs, CO consumption also causes neuronal damage via disturbing the levels of different proteins such as (GFAP and b-tubulin III). The mechanistic studies show that AQs present in CO have the potential to disturb the cellular homeostasis via binding to DNA, increasing the production ROS and showing inhibitory effects on essential enzymes etc. Therefore, AQs have been observed to be the primary culprit agents contributing to the toxicity of CO in children and animals.

CONCLUSION

Despite its therapeutic potential, CO consumption can be detrimental if consumed in high amounts. A thorough analysis of literature reveals that AQs are the primary factors contributing to toxicity of CO seeds. Exposure to CO seeds causes HME, which is a serious life threatening condition for the malnourished children from lower strata. Multiple mechanisms are involved in the CO induced HME in patients. Lack of appropriate diagnostic measures and a poor understanding of the CO toxicity mechanism in humans and animals complicate the clinical management of CO poisoning subjects. Therefore, development of point of care diagnostic kits shall help in early diagnosis & suitable management of CO poisoning.

Physiochemical, Insecticidal, and Antidiabetic Activities of Senna occidentalis Linn Root

The present study aimed to investigate the physiochemical activities of Senna occidentalis (Linn) roots and phytochemicals as insecticidal (ethyl acetate and methanol) and antidiabetic (ethanolic extract) activities. Physicochemical properties were carried out by using Association of Official Analytical Chemist methods; thin layer chromatography was carried out according to the Stahl method. Larvicidal activity and LD₅₀ were studied against the third instar of Culex quinquefasciatus mosquito larvae to detect and extract toxicity. The ethanolic extracts of the roots were orally tested at the dose 200 mg/kg for the hypoglycemic effect on induced hyperglycemia in normal rats, assessed in the ethanol extract, and were compared with diabetic control and standards glibenclamide 10 mg/kg. Physiochemical parameters showed high rate in the nitrogen-free extract (69.6%), curd fiber (14.5%), crude proteins (8.15%), ether extract (3.75%), and both ash and moisture (2%), and high concentrations values were found in potassium (43 mg/l) followed by phosphorous (28.5 mg/l), calcium (15 mg/l), sodium (3.65 mg/l), and magnesium (0.145 mg/l). In this part, phytochemical compounds showed high amount of alkaloids, triterpene, flavonoids, tannins, sugars, and few amount of anthraquinone glycosides. Thin-layer chromatography (TLC) studies different colored phytochemical constituted with different Rf values. All the spots are colored under UV light, but some are localized colorless after spaying. The ethyl acetate (EtAc) extract showed eight spots, and the methanol (MeOH) extract showed thirteen spots. The larvicidal activity showed that the ethyl acetate extract was safe against mosquito larvae with an LD₅₀ value 1412.54 (p < 0.05), and the methanol extract had moderate larvicidal activity against mosquito larvae with an LD₅₀ value 257.54 (p < 0.05), while the ethanolic extract of Senna occidentalis (L.) causes a favorable hypoglycemic activity when compared to control significant reduction by [53.15%, 32.87%, and 20.94%], respectively, as well as standard glibenclamide. Based on the various data of the physicochemical parameters, TLC spots, and phytochemical compounds of Senna occidentalis root, they could be used as references standards for manufacturing units of Senna occidentalis root larvicidal and antidiabetic drugs.

Interaction mechanism of aloe-emodin with trypsin: molecular structure-affinity relationship and effect on biological activities

The molecular mechanism of interaction between aloe-emodin (AE) and trypsin was investigated, exhibiting remarkable outcomes. To detect the interaction mechanism, the binding of AE with trypsin was examined by a multi-spectroscopy and molecular docking method. Results showed that the binding of AE and trypsin would lead to static quenching and their binding forces were van der Waals forces and hydrogen bonding. The results of simultaneous and three-dimensional fluorescence spectroscopy showed that the combination of AE and trypsin caused changes in the microenvironment around the trypsin fluorophore, which might change the spatial structure of trypsin. FT-IR spectroscopy showed that the contents of α-helix and β-turn in trypsin were decreased and the contents of β-sheet, random coil and antiparallel β-sheet were increased. Moreover, all these experimental results were verified and reasonably explained by molecular docking results. We also investigated the enzyme activity of trypsin and the antioxidant activity of AE. The results showed that both the enzyme activity of trypsin and the antioxidant activity of AE were decreased after interaction between AE and trypsin. The findings outlined in this study should elucidate the molecular mechanisms of interaction between AE and trypsin and contribute to making full use of AE in the food industry.

Elucidation of binding mechanism of dibutyl phthalate on bovine serum albumin by spectroscopic analysis and molecular docking method

Dibutyl phthalate has been illegally used in beverages and directly affects the human health. Herein, the interaction occurred between dibutyl phthalate and bovine serum albumin was studied. The experimental results demonstrated that dibutyl phthalate could bind to bovine serum albumin and statically quench the intrinsic fluorescence of this protein. Circular dichroism measurements proved that the binding of dibutyl phthalate would lead to an obvious decrease of α-helix content in the bovine serum albumin. Molecular docking analysis clarified the fluorescence quenching mechanism, size distribution and zeta potential variation, conformational change of BSA, the site marker competitive fluorescence quenching and the interaction mechanism of dibutyl phthalate to bovine serum albumin. This work provided a useful information for the binding of dibutyl phthalate to protein.

Aloe-emodin: A review of its pharmacology, toxicity, and pharmacokinetics

Aloe-emodin is a naturally anthraquinone derivative and an active ingredient of Chinese herbs, such as Cassia occidentalis, Rheum palmatum L., Aloe vera, and Polygonum multiflorum Thunb. Emerging evidence suggests that aloe-emodin exhibits many pharmacological effects, including anticancer, antivirus, anti-inflammatory, antibacterial, antiparasitic, neuroprotective, and hepatoprotective activities. These pharmacological properties lay the foundation for the treatment of various diseases, including influenza virus, inflammation, sepsis, Alzheimer's disease, glaucoma, malaria, liver fibrosis, psoriasis, Type 2 diabetes, growth disorders, and several types of cancers. However, an increasing number of published studies have reported adverse effects of aloe-emodin. The primary toxicity among these reports is hepatotoxicity and nephrotoxicity, which are of wide concern worldwide. Pharmacokinetic studies have demonstrated that aloe-emodin has a poor intestinal absorption, short elimination half-life, and low bioavailability. This review aims to provide a comprehensive summary of the pharmacology, toxicity, and pharmacokinetics of aloe-emodin reported to date with an emphasis on its biological properties and mechanisms of action.

Separation of Protein-Binding Anthraquinones from Semen Cassiae Using Two-Stage Foam Fractionation

Anthraquinones are compounds of high medicinal value in many plants. Based on their good protein binding affinity, foam fractionation was attempted to separate them using proteins in the aqueous extract of Semen Cassiae as collectors. Firstly, the interaction between anthraquinones and Semen Cassiae proteins has been analyzed by the Stem–Volmer equation with physcion as a standard. The results show that physcion had good interaction with the proteins via hydrophobic forces. More importantly, the proteins effectively assisted the foam fractionation of several anthraquinones including aurantio-obtusifolin, aloe-emodin, rhein, emodin, chrysophanol, and physcion. On this basis, a two-stage foam fractionation technology was developed for process intensification using a foam fractionation with vertical sieve trays (VSTs). VSTs, initial feed concentration of total anthraquinones, temperature, volumetric air flow rate and pore diameter of gas distributor had significant effects on enrichment ratio and recovery yield of anthraquinones. Under suitable conditions, the enrichment ratio of total anthraquinones reached 47.0 ± 4.5 with a concentration of 939 ± 94 mg/L in the foamate while their total recovery percentage reached more than 47.7%. In addition, foam fractionation also increased the purity and hydroxyl radical scavenging activity of total anthraquinones. The results had significant implications for the separation of anthraquinones from Semen Cassiae.

Exploration of the hepatoprotective chemical base of an orally administered herbal formulation (YCHT) in normal and CCl4-intoxicated liver injury rats. Part 2: Hepatic disposition in vivo and hepatoprotective activity in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Yin-Chen-Hao Tang (YCHT) has been a very popular, hepatoprotective three-herb formula with an unclear chemical base.

AIM OF THIS STUDY

To reveal the hepatoprotective chemical base of oral-dosed YCHT, we bridged the hepatic disposition of six compounds in vivo and their hepatoprotection in vitro.

MATERIALS AND METHODS

In vivo, following the oral administration of YCHT in normal and CCl₄-induced liver injury rats, the determinations of chlorogenic acid, 4-hydroxyacetophenone, geniposide, genipin, rhein and emodin were conducted in the portal vein plasma, the liver, and the systemic plasma. In vitro, the hepatoprotective activities of these compounds were determined in the CCl₄-induced HepG2 cells.

RESULTS

Consistent with the highest content in YCHT, geniposide had the highest exposure in vivo. Inconsistent with the negligible content, rhein, 4-hydroxyacetophenone, emodin and genipin showed substantial hepatic accumulations. In contrast, chlorogenic acid, an ingredient that has a high content in YCHT, elicited no hepatic exposure. In normal rats, the hepatic disposition prevented the compounds entering into the systemic plasma from the portal vein plasma by 44.9-100%, except for rhein. CCl₄-induced liver injury caused a decreased hepatic exposure of 4-hydroxyacetophenone, rhein and emodin by 50%. In vitro, all six compounds exerted the hepatoprotection by increasing cell viability, decreasing hepatic marker enzymes and inhibiting lipid peroxidation at varying levels.

CONCLUSION

Geniposide, rhein, emodin, 4-hydroxyacetophenone and genipin directly resisted liver injury in oral-dosed YCHT, while chlorogenic acid likely played an indirect role. This study proved that YCHT exerted hepatoprotection through multiple components and multiple actions. However, close attention should be paid to the possible side effects and oral dosage of YCHT in clinics.

Aloe emodin induces hepatotoxicity by activating NF-κB inflammatory pathway and P53 apoptosis pathway in zebrafish

The aim of this study was to investigate the hepatotoxic effect and its underlying mechanism of aloe emodin (AE). AE was docked with the targets of NF-κB inflammatory pathway and P53 apoptosis pathway respectively by using molecular docking technique. To verify the results of molecular docking and further investigate the hepatotoxicity mechanism of AE, the zebrafish Tg (fabp10: EGFP) was used as an animal model in vivo. The pathological sections of zebrafish liver were analyzed to observe the histopathological changes and Sudan black B was used to study whether there were inflammatory reactions in zebrafish liver or not. Then TdT-mediated dUTP Nick-End Labeling (TUNEL) was used to detect the apoptotic signal of zebrafish liver cells, finally the mRNA expression levels as well as the protein expression levels of the targets in NF-κB and P53 pathways in zebrafish were measured by quantitative Real-Time PCR (qRT-PCR) and western blot. Molecular docking results showed that AE could successfully dock with all the targets of NF-κB and P53 pathways, and the docking scores of most of the targets were equal to or higher than that of the corresponding ligands. Pathological sections showed AE could cause zebrafish liver lesions and the result of Sudan black B staining revealed that AE blackened the liver of zebrafish with Sudan black B. Then TUNEL assay showed that a large number of dense apoptotic signals were observed in AE group, mainly distributed in the liver and yolk sac of zebrafish. The results of qRT-PCR and western blot showed that AE increased the mRNA and protein expression levels of pro-inflammatory and pro-apoptotic targets in NF-κB and P53 pathways. AE could activate the NF-κB inflammatory pathway and the P53 apoptosis pathway, and its hepatotoxic mechanism was related to activation of NF-κB-P53 inflammation-apoptosis pathways.

Ultrasound mediated accelerated Anti-influenza activity of Aloe vera

Aloe vera (AV) is popular and has been commercialized as a beauty product, laxative, herbal medicine, the antimicrobial activity of AV is proven. The antiviral activity of AV however, has not been well documented except for a handful reports. Till date extraction of AV compounds is popularized using organic solvents, since the active components are effectively extracted in methanol. In the current work, we have employed a 5 min ultrasound based extraction for the effective extraction of aloin and aloe-emodin compounds from AV in water. This rapid, one-pot extraction process resulted in enhanced extraction of flavonoids and phenolics and enrichment of the aloin and aloe-emodin moieties in the ulrasonicated water extracts. The extracts were tested for their anti-influenza activity and, the results showed that the ultrasound extraction enabled the water extracts to show excellent anti influenza activity comparable to that seen in the methanolic extracts. Compared to the methanolic extracts which showed high cytotoxicity, the water extracts showed zero cytotoxicity. Spectrophotometric scans of the extracts confirmed the enrichment of the aloin and aloe emodin peaks in the ultrasonicated extracts of AV, suggesting their handiwork behind the anti-influenza activity. The demonstrated technique if appropriately implicated, would lead to promising solutions in the pharmaceutical pursuit against influenza virus.

A QSAR-based mechanistic study on the combined toxicity of antibiotics and quorum sensing inhibitors against Escherichia coli

Quorum sensing inhibitors (QSIs) have attracted increasing attention due to their potential roles as the antibiotic alternatives. The combination of QSIs and antibiotics in clinical use and their subsequent release into the environment may result in joint effects on the ecology and environment, which has not received enough concerns yet. In this study, eight potential QSIs and three types of commonly used antibiotics, i.e., sulfonamides (SAs), β-lactams and tetracyclines (TCs), were investigated for their combined toxicity on Escherichia coli (E. coli). The QSAR models for the combined toxicity were constructed using the interaction energies between the chemicals and their target proteins as calculated by molecular docking. It was revealed that the SAs and QSIs presented either additive or antagonistic joint effects in the mixture toxicity test, while β-lactams and TCs showed only antagonistic effects with the QSIs. The analysis on the coefficients in the QSAR models suggested that the QSIs in the mixtures were more involved in the interaction with the proteins than the antibiotics. This study will help better understand the risks of joint exposure to the antibiotics and QSIs, and provide a new perspective for the study of the combined toxicity mechanism.

Interaction of anthraquinones of Cassia occidentalis seeds with DNA and Glutathione

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Emodin has the maximum binding affinity to calf thymus DNA.

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Anthraquinones form GSH conjugates.

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Anthraquinones oxidizes GSH to GSSG.

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Cytotoxicity of anthraquinones are linked to their DNA binding affinity.

Consumption of Cassia occidentalis (CO) seeds has been associated with the hepatomyoencephalopathy (HME) in children. Recently, we have characterized the toxic anthraquinones (AQs) such as Emodin, Rhein, Aloe-emodin, Chrysophanol and Physcion in CO seeds and detected these moieties in the bio fluids of CO poisoning cases. As AQs were detected in the serum of HME patients, their interaction with key biomolecules including protein, DNA and glutathione (GSH) is imperative. In this regard, we have previously reported the interaction of these AQs with serum albumin protein and their subsequent biological effects. However, the interaction of these AQs with DNA and GSH remained unexplored. In the present work, we have studied the binding of these AQs of CO seeds with DNA and GSH by fluorescence spectroscopy, UV–vis spectral analysis, molecular docking, and biochemical studies. Results indicated a higher binding affinity for Emodin (K_a = 3.854 × 10⁴ L mol⁻¹ S⁻¹), Aloe-emodin (K_a = 0.961 × 10⁴ L mol⁻¹ S⁻¹) and Rhein (K_a = 0.034 × 10⁴ L mol⁻¹ S⁻¹) towards calf thymus DNA may be associated with their higher cytotoxicity. Alternatively, Physcion and Chrysophanol which showed less cytotoxicity in our earlier studies exhibited very low DNA binding. The binding pattern of all these AQs is consistent with the in-silico data. Absorption spectroscopy studies indicated the possible formation of GSH conjugate with Aloe-emodin and Physcion. Further biochemical measurement of GSH and GSSG (Glutathione disulfide) following incubation with AQs indicated that Aloe-emodin (28%) and Rhein (30%) oxidizes GSH to GSSG more as compared to other AQs. Taken together, these results suggest that the higher cytotoxicity of Rhein, Emodin and Aloe-emodin may be attributed to their potent DNA and GSH binding affinity.

Direct inhibition of Keap1–Nrf2 interaction by egg-derived peptides DKK and DDW revealed by molecular docking and fluorescence polarization

DKK and DDW, egg-derived direct inhibitors of the Keap1–Nrf2 interaction, screening by fluorescence polarization assays and cell experiments.

Immunomodulatory potential of Rhein, an anthraquinone moiety of Cassia occidentalis seeds

Rhein, the most toxic anthraquinone moiety in Cassia occidentalis seeds, has been associated with hepatomyoencephalopathy (HME) in children. Structural and functional alterations in the lymphoid organs have been reported both in HME patients and experimental animals indicating a possibility of the dysfunction of immune system following exposure to CO seeds or its toxic anthraquinones (Panigrahi et al., 2014a). In the present study the mechanism of immune response of Rhein in splenocytes has been investigated by measuring functional assays of lymphocyte, cell surface receptor expression and analysis of cytokine levels. Results indicate that Rhein at a maximum dose of 10 μM is non cytotoxic up to 72 h in splenocytes. In addition to its potential to decrease the allogenic response of T-cells, Rhein significantly suppresses the proliferation of the concavalin A (Con A) and lipopolysaccharide (LPS) stimulated splenocytes. Lymphocyte receptor expression analysis revealed that Rhein exposure significantly down regulate the expression of CD3e, CD4, CD8, CD28, CD69 molecules in T-cells. The expression of CD19, CD28, CD40 in B-cells were also found to be significantly decreased following Rhein exposure. In accordance with the functional responses, Rhein treatment significantly lowered the expression of IL2 and IL6 cytokines in Con A stimulated splenocytes, and IL6, IL10, IFNγ and TNFα in LPS stimulated splenocytes. Over all, the study suggests the immunomodulatory activity of Rhein and that it would be useful in understanding the immune response of CO seeds in human subjects.