Antibacterial and cytotoxic activities of naphthoquinone pigments from Onosma visianii Clem

Anoikis and cancer cell differentiation: novel modes of shikonin derivatives anticancer action in vitro

BACKGROUND

Shikonin is a naturally occurring naphthoquinone found in the roots of several genera of the Boraginaceae family, widely known for its numerous biological activities, such as antiinflammatory, antioxidant, antimicrobial and anticancer. In this study, the antitumor effect of six naphthoquinones isolated from the roots of Onosma visianii was evaluated using two cell lines, mouse melanoma B16 and highly aggressive rat glioma cell line C6.

METHODS AND RESULTS

All examined shikonins dose-dependently decreased the viability of tested cells, with compounds 5 and 6 being the most potent ones and hence subjected to further analysis. The diminished viability of B16 melanoma cells was in correlation with detected caspase-mediated apoptosis. Importantly, observed altered cell morphology along with the loss of dividing potential upon exposure to both shikonins implied reprogram of B16 cell phenotype. Elevated expression of myelin basic protein indicated the acquirement of Schwann-like cell phenotype, while detected autophagy might be connected to this phenomenon. On the contrary, upon exposure to both agents, C6 cells underwent specific cell death-anoikis, provoked by detachment from the extracellular matrix and compromised integrin signaling. Oppositely to compound 5, compound 6 realized anoikis in a caspase-independent manner and under sustained ERK1/2 activation, indicating the deviation from standard proanoikis signaling.

CONCLUSIONS

Herein, we have pointed out the diversity and novelty in the mode of action of shikonin derivatives depending on the tumor cell features, which represents a good platform for new investigations of these promising natural compounds.

1,4-Naphthoquinone (CNN1) Induces Apoptosis through DNA Damage and Promotes Upregulation of H2AFX in Leukemia Multidrug Resistant Cell Line

The multidrug resistance (MDR) phenotype is one of the major obstacles in the treatment of chronic myeloid leukemia (CML) in advantage stages such as blast crisis. In this scenario, more patients develop resistance mechanisms during the course of the disease, making tyrosine kinase inhibitors (TKIs) target therapies ineffective. Therefore, the aim of the study was to examine the pharmacological role of CNN1, a para-naphthoquinone, in a leukemia multidrug resistant cell line. First, the in vitro cytotoxic activity of Imatinib Mesylate (IM) in K-562 and FEPS cell lines was evaluated. Subsequently, membrane integrity and mitochondrial membrane potential assays were performed to assess the cytotoxic effects of CNN1 in K-562 and FEPS cell lines, followed by cell cycle, alkaline comet assay and annexin V-Alexa Fluor® 488/propidium iodide assays (Annexin/PI) using flow cytometry. RT-qPCR was used to evaluate the H2AFX gene expression. The results demonstrate that CNN1 was able to induce apoptosis, cell membrane rupture and mitochondrial membrane depolarization in leukemia cell lines. In addition, CNN1 also induced genotoxic effects and caused DNA fragmentation, cell cycle arrest at the G2/M phase in leukemia cells. No genotoxicity was observed on peripheral blood mononuclear cells (PBMC). Additionally, CNN1 increased mRNA levels of H2AFX. Therefore, CNN1 presented anticancer properties against leukemia multidrug resistant cell line being a potential anticancer agent for the treatment of resistant CML.

Antiproliferative and cytotoxic effects of bioactive compounds isolated from Onosma bourgaei

Onosma species have been used commonly for traditional medicine for years due to their bioactive compounds content. Onosma bourgaei aerial part was extracted with hexane and methanol successively. The methanol extract was subjected to chromatographic techniques to isolate allantoin (1), 3,4-dihydroxybenzaldehyde (2), luteolin-7-O-glucoside (3), apigenin-7-O-β-glucoside (4), diosmetin-7-O-β-glucoside (5), rosmarinic acid (6), and globoidnan A (7). The structure of isolated compounds were identified by spectroscopic techniques such as 1D-NMR, 2D-NMR, FTIR, and LC-TOF/MS/MS. Antiproliferative activity of extract and natural compounds were carried out using HeLa (human epithelial cervix adenocarcinoma, ATCC® CCL-2™), HT29 (human colorectal adenocarcinoma, ATCC® HTB38™), MCF7 (human mammary gland adenocarcinoma, ATCC® HTB22™), and A549 (human lung carcinoma, ATCC® CCL185™) cancerous cells and normal cells, FL (human epithelial amnion cell, ATCC® CCL62™). Lactate dehydrogenase (LDH) was performed for cytotoxicity. The compounds, 4, 6, and 7 displayed the strong antiproliferative activity against corresponding cell lines. Apigenin-7-O-β-glucoside (4) revealed the excellent activity on HeLa, HT29, A549, and MCF6 cancer cell lines with the values of (IC_50, µM) 167.3, 196.8 181.1, and 203.5, respectively, compared standard compound, cisplatin.

Evaluation of the phenolic contents and antibacterial activity of different concentrations of Onosma chlorotricum Boiss

Because of side effects and increasing resistance to antibiotics, considerable attention hasbeen given to extract sand biologically active compounds isolated from medicinal plants. In the present study, phytochemical screening and antibacterial activities of different concentrations of various extracts of Onosma chlorotricum were evaluated and compared with those of vancomycin and amikacin. Total phenolic and flavonoid contents and the antibacterial activity of methanol, n-hexane, and aqueous extracts (5 mg/ml to 0.156 mg/ml final concentration) of O. chlorotricum against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli were evaluated using disc diffusion and microdilution methods. Total phenolic and flavonoid contents were determined according to the Folin-Ciocalteu and aluminum chloride colorimetric assays, respectively. The results showed that the total phenolic and flavonoid contents of these extracts ranged from 56.10 ± 0.13 to 74.12 ± 0.05 mg GAE/g dry extract and from 19.3 ± 0.6 to 23.20 ± 0.41 mg QE/g dry extract, respectively. The methanol extract with the highest phenolic and flavonoid content showed the highest antibacterial activity against all the tested bacterial strains, with the highest inhibition zone of 21 ± 0.7 mm and the lowest MIC and MBC values of 78.12 μg/ml for S. aureus. The antibacterial effects and the total phenolic content of O. chlorotricum were remarkable. The results suggest that the effects of methanol extract on wound healing could be tested in an animal model.

Onosma mutabilis: Phytochemical composition, antioxidant, cytotoxicity, and acute oral toxicity

The traditional use of Onosma L. species as a remedy motivated scientists to discover great biological/pharmacological potentials in this plant. In the current study, in addition to the phytochemical composition of methanol (MeOH), water, and ethyl acetate extract of aerial parts of Onosma mutabilis Boiss., an endemic plant species in the flora of Kurdistan, Iraq, in vitro antioxidant, cytotoxicity, and oral toxicity activity were investigated. Results of total phenolic and total flavonoid tests show the MeOH extract superiority, and the results of Gas chromatography-mass spectrophotometer(GS/GS-MS) show 18 chemical compounds in the MeOH extract, and the majority of the detected compounds were alkaloids (78.77%) and steroids (11.48%), namely as 5,8-dihydroxy-2-(4-methylpent-3-enyl) naphthalene-1,4-dione (48.60%), 3-O-Methyl-d-glucose (27.49%), β-Sitosterol (6.81%), Phenol, 2,4-bis (1,1-dimethyl ethyl)-, phosphite (3.46%), and 24,25-Dihydroxycholecalciferol (3.14%). Results of the antioxidant tests show the MeOH extract superiority in the phosphomolybdenum assay, radical scavenging [on 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)] assays, and reducing power [cupric reducing antioxidant capacity (CUPRAC) and ferric reducing antioxidant power (FRAP)] assays (1.45, 3.54, 2.33, 1.12, 1.62, mg/ml, respectively). The cytotoxicity results of the plant extract are presented as IC50 (inhibitory concentration at 50%) on the prostate cancer cells (DU-145), mammary cancer cells (MCF-7), and human cervix carcinoma (Hep2c), at which values ranged from 28.79 to 41.83 μg/ml. Results of the acute toxicity in the dose-dependent trail (100, 200, 300, 600 mg/kg of MeOH) show the absence of the behavior and appearance changes of female Wister rats. Overall, O. mutabilis extract exhibited significant natural potentials probably because of its polar phytochemicals, which could be an alternative source for remedial, nutrient, and cosmetic manufacture.

Shikonin Derivatives from Onsoma visianii Decrease Expression of Phosphorylated STAT3 in Leukemia Cells and Exert Antitumor Activity

Antitumor effects of shikonins on chronic lymphocytic leukemia (CLL) and B-cell prolymphocytic leukemia (B-PLL) are mostly unexplored. The antitumor activity of shikonins, isolated from Onosma visianii Clem (Boraginaceae), in BCL1, mouse CLL cells and JVM-13, human B-PLL cells was explored in this study. The cytotoxicity of shikonin derivatives was measured by an MTT test. Cell death, proliferation, cell cycle, and expression of molecules that control these processes were analyzed by flow cytometry. Expression of STAT3-regulated genes was analyzed by real-time q-RT-PCR (Quantitative Real-Time Polymerase Chain Reaction). The antitumor effects of shikonin derivatives in vivo were analyzed, using flow cytometry, by detection of leukemia cells in the peripheral blood and spleens of mice intravenously injected with BCL1 cells. The two most potent derivatives, isobutyrylshikonin (IBS) and α-methylbutyrylshikonin (MBS), induced cell cycle disturbances and apoptosis, inhibited proliferation, and decreased expression of phospho-STAT3 and downstream-regulated molecules in BCL1 and JVM-13 cells. IBS and MBS decreased the percentage of leukemia cells in vivo. The link between the decrease in phosphorylated STAT3 by MBS and IBS and BCL1 cell death was confirmed by detection of enhanced cell death after addition of AG490, an inhibitor of Jak2 kinase. It seems that IBS and MBS, by decreasing STAT3 phosphorylation, trigger apoptosis, inhibit cell proliferation, and attenuate leukemia cell stemness.

Onosma bracteata Wall. induces G0/G1 arrest and apoptosis in MG-63 human osteosarcoma cells via ROS generation and AKT/GSK3β/cyclin E pathway

Onosma bracteata Wall. (Boraginaceae), commonly known as "gaozaban" is a highly valuable medicinal herb, useful in the treatment of body swellings, abdominal pain, eye-related problems, fever, and urinary calculi. The present study was performed to investigate the antioxidant properties of extract/fractions, viz. ethanol (Obeth) extract, hexane (Obhex) fraction, chloroform (Obcl) fraction, ethyl acetate (Obea) fraction, butanol (Obbu) fraction, and aqueous (Obaq) fraction isolated from O. bracteata. Obea fraction showed stronger free radical quenching ability in various antioxidant assays, as compared to the other fractions. Obea fraction with effective free radical-scavenging properties was further evaluated for the antiproliferative activity against human osteosarcoma MG-63, human neuroblastoma IMR-32, and human lung cancer A549 cell lines using MTT assay. Obea fraction showed strong cytotoxicity with GI₅₀ value of 88.56, 101.61, and 112.7 μg/ml towards MG-63, IMR-32, and A549 cells respectively. Mechanistic studies revealed that Obea fraction in osteosarcoma MG-63 cells increased reactive oxygen species (ROS) level and reduced mitochondrial membrane potential. In the presence of Obea, the cells were found to be arrested in the G₀/G₁ phase in a dose-dependent manner which is also confirmed by the enhancement in the early apoptotic cell population in flow cytometer analysis. Western blotting demonstrated the decrease in expression of p-NFκB, COX-2, p-Akt, and Bcl-xL, whereas upregulation was observed in the expression of GSK-3β, p53, caspase-3, and caspase-9 proteins. RT-qPCR studies revealed downregulation of Bcl-2, cyclin E, CDK2, and mortalin gene expression and upregulation in the expression of p53 genes. The antioxidant and cytotoxic potential of Obea was attributed to the presence of catechin, kaempferol, onosmin A, and epicatechin, as revealed by HPLC analysis. This is the first report regarding the antiproliferative potential of O. bracteata against osteosarcoma.

Journey on Naphthoquinone and Anthraquinone Derivatives: New Insights in Alzheimer's Disease

Alzheimer’s disease (AD) is a progressive neurodegenerative disease that is characterized by memory loss, cognitive impairment, and functional decline leading to dementia and death. AD imposes neuronal death by the intricate interplay of different neurochemical factors, which continue to inspire the medicinal chemist as molecular targets for the development of new agents for the treatment of AD with diverse mechanisms of action, but also depict a more complex AD scenario. Within the wide variety of reported molecules, this review summarizes and offers a global overview of recent advancements on naphthoquinone (NQ) and anthraquinone (AQ) derivatives whose more relevant chemical features and structure-activity relationship studies will be discussed with a view to providing the perspective for the design of viable drugs for the treatment of AD. In particular, cholinesterases (ChEs), β-amyloid (Aβ) and tau proteins have been identified as key targets of these classes of compounds, where the NQ or AQ scaffold may contribute to the biological effect against AD as main unit or significant substructure. The multitarget directed ligand (MTDL) strategy will be described, as a chance for these molecules to exhibit significant potential on the road to therapeutics for AD.

Biosynthesis of silver nanoparticles using Onosma sericeum Willd. and evaluation of their catalytic properties and antibacterial and cytotoxic activity

In this study, silver nanoparticle (AgNP) synthesis was carried out using Onosma sericeum Willd. aqueous extract for the first time, with a simple, economical, and green method without the need for any other organic solvent or external reducing or stabilizing agent. A variety of AgNPs, all of different particle sizes, were synthesized by controlling the silver ion concentration, extract volume, temperature, and pH. It was determined that the optimum conditions for AgNP synthesis were 1 mM AgNO3, pH 8, 25 °C, 20 g/200 mL extract, silver nitrate, and extract ratio 5:1 (v/v). The AgNPs were defined using UV-Vis spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The particle size distribution and zeta potential measurements of the AgNPs were measured using the dynamic light scattering (DLS) technique. It was determined that the AgNPs with a particle size of less than 10 nm showed a higher catalytic effect in the reduction of 2-nitrobenzenamine. It was also found that these nanoparticles had a cytotoxic effect on the MCF-7 breast cancer cell line depending on dosage and time. The resulting IC50 values were between 76.63 µg/mL and 169.77 µg/mL. Furthermore, the biosynthesized AgNPs showed effective antibacterial activity against the Acinetobacter baumannii bacteria. The results of the study showed that synthesized AgNPs can have a promising role in biomedical and nanobiotechnology applications.

Pharmacology, toxicity and pharmacokinetics of acetylshikonin: a review

CONTEXT

Acetylshikonin, a naphthoquinone derivative, is mainly extracted from some species of the family Boraginaceae, such as Lithospermum erythrorhizon Sieb. et Zucc., Arnebia euchroma (Royle) Johnst., and Arnebia guttata Bunge. As a bioactive compound, acetylshikonin has attracted much attention because of its broad pharmacological properties.

OBJECTIVE

This review provides a comprehensive summary of the pharmacology, toxicity, and pharmacokinetics of acetylshikonin focussing on its mechanisms on the basis of currently available literature.

METHODS

The information of acetylshikonin from 1977 to 2020 was collected using major databases including Elsevier, Scholar, PubMed, Springer, Web of Science, and CNKI. Acetylshikonin, pharmacology, toxicity, pharmacokinetics, and naphthoquinone derivative were used as key words.

RESULTS

According to emerging evidence, acetylshikonin exerts a wide spectrum of pharmacological effects such as anticancer, anti-inflammatory, lipid-regulatory, antidiabetic, antibacterial, antifungal, antioxidative, neuroprotective, and antiviral properties. However, only a few studies have reported the adverse effects of acetylshikonin, with respect to reproductive toxicity and genotoxicity. Pharmacokinetic studies demonstrate that acetylshikonin is associated with a wide distribution and poor absorption.

CONCLUSIONS

Although experimental data supports the beneficial effects of this compound, acetylshikonin cannot be considered as a therapy drug without further investigations, especially, on the toxicity and pharmacokinetics.

Redox status, DNA and HSA binding study of naturally occurring naphthoquinone derivatives

In the present work we modified the procedure for isolation of naphthoquinones α-methylbutyrylshikon (1), acetylshikonin (2) and β-hydroxyisovalerylshikonin (3) from Onosma visianii Clem. We also investigated possible mechanisms of 1, 2 and 3 as antitumor agents. Accordingly, we estimated concentrations of superoxide anion radical (O₂^.-), nitrite (NO₂ ^-) and glutathione in HCT-116 and MDA-MB-231 cell lines. Compounds 1 and 3 expressed significant prooxidative activity, while all tested compounds exhibited significant increase in nitrite levels. Also, all examined compounds significantly increased the concentration of oxidized glutathione (GSSG), suggesting significant prooxidative disbalance. The levels of reduced glutathione (GSH) were also elevated as a part of antioxidative cell response. The data indicate that induced oxidative imbalance could be one of the triggers for previously recorded decreased viability of HCT-116 and MDA-MB-231 cells exposed to tested naphthoquinone derivatives. Moreover, we examined interactions mode of compounds 1, 2 and 3 with CT-DNA as one of the crucial targets of many molecules that express cytotoxic activity. The results obtained by UV-visible, fluorescence and molecular docking study revealed that 1, 2 and 3 bound to CT-DNA through minor groove binding. Furthermore, the interactions between HSA and 1, 2 and 3 were examined employing the same methods as for the CT-DNA interaction study. Based on the obtained results, it can be concluded that naphthoquinones 1, 2 and 3 could be effectively transported by human serum albumin. As a conclusion, this study provides further insight of antitumor activity of selected naphthoquinones.

Effect of β-cyclodextrin encapsulation on cytotoxic activity of acetylshikonin against HCT-116 and MDA-MB-231 cancer cell lines

Acetylshikonin (AcSh), as a red colored pigment found in roots of the plants from family Boraginaceae, showed excellent cytotoxic activity. Due to its hydrophobic nature, and thus poor bioavailability, the aim of this study was to prepare acetylshikonin/β-cyclodextrin (AcSh/β-CD) inclusion complex by using coprecipitation method, characterize obtained system by using UV/VIS, IR and ¹H NMR spectroscopy, and determine cytotoxic activity. Phase solubility test indicated formation of A_L-type binary system (substrate/ligand ratio was 1:1 M/M), with stability constant Ks of 306.01 M⁻¹. Formation of noncovalent bonds between inner layer of the hole of β-CD and AcSh was observed using spectroscopic methods. Notable changes in chemical shifts of two protons (−0.020 ppm) from naphthoquinone moiety (C₆-H and C₇-H), as well as protons from hydroxyl groups (−0.013 and −0.009, respectively) attached to C₅ and C₈ carbons from naphthoquinone part indicate that the molecule of AcSh enters the β-CD cavity from the aromatic side. Cytotoxic activity against HCT-116 and MDA-MB-231 cell lines was measured by MTT test and clonogenic assay. Mechanisms of action of free AcSh and inclusion complex were assessed by flow cytometry. In comparison to free AcSh, AcSh/β-CD showed stronger short-term effect on HCT-116 cells and superior long-term effect on both cell lines. Inclusion complex induced more pronounced cell cycle arrest and autophagy inhibition, and induced increase in accumulation of intracellular ROS more effectively than free AcSh. In conclusion, AcSh/β-CD binary system showed better performances regarding cytotoxic activity against tested tumor cell lines.

Identification of Onosma visianii Roots Extract and Purified Shikonin Derivatives as Potential Acaricidal Agents against Tetranychus urticae

There is an increasing need for the discovery of reliable and eco-friendly pesticides and natural plant-derived products may play a crucial role as source of new active compounds. In this research, a lipophilic extract of Onosma visianii roots extract containing 12% of shikonin derivatives demonstrated significant toxicity and inhibition of oviposition against Tetranychus urticae mites. Extensive chromatographic separation allowed the isolation of 11 naphthoquinone derivatives that were identified by spectral techniques and were tested against Tetranychus urticae. All the isolated compounds presented effects against the considered mite and isobutylshikonin (1) and isovalerylshikonin (2) were the most active, being valuable model compounds for the study of new anti-mite agents.