Liposomal thymoquinone effectively combats fluconazole-resistant Candida albicans in a murine model

Investigating anti-cancer activity of dual-loaded liposomes with thymoquinone and vitamin C

Background: Thymoquinone (TQ) and vitamin C (Vit C) have demonstrated individual anticancer effects in various studies. TQ exhibits inhibitory properties against tumor growth, induces apoptosis, while Vit C protects against DNA damage and oxidative stress. Aim: Formulation of TQ and Vit C combination into liposomes using two methods and investigate the synergistic anticancer. Method: Liposomal preparations were characterized, and the purity of drug components was confirmed using encapsulation efficiency (EE %). Results: In vitro cell viability studies demonstrated the inhibitory effect of TQ and Vit C against colorectal (HT29, 5.5 ± 0.9 μM) and lung cancer (A549, 6.25 ± 0.9 μM) cell lines with combination index <1. Conclusion: The formulation of TQ and Vit C displayed synergistic anticancer activity.

Thymoquinone attenuates inflammation in C. Albicans keratitis by activating Nrf2/HO-1 signaling pathway and reducing fungal load

PURPOSE

This study aims to investigate the anti-inflammatory and antifungal properties of thymoquinone (TQ) and elucidate its mechanism of action in the context of C. albicans keratitis.

METHODS

Various methods were employed to identify a safe and effective concentration of TQ with antifungal properties, including the determination of the minimum inhibitory concentration (MIC), the cell counting kit-8 (CCK-8) test, and the Draize experiment. The severity of fungal keratitis (FK) was assessed through clinical ratings and slit-lamp imaging. Fungus burden was determined using plate counting and periodic acid Schiff (PAS) staining. Neutrophil infiltration and activity were investigated through immunofluorescence staining (IFS), myeloperoxidase (MPO) analysis, and hematoxylin and eosin (HE) staining. To explore the anti-inflammatory effects of TQ and its mechanism of action, we employed RT-PCR, ELISA, and western blot techniques.

RESULTS

TQ effectively controlled fungal growth at a concentration of 50 µg/mL while preserving the integrity of mouse corneas. Human corneal epithelial cells (HCECs) remained unaffected by TQ at concentrations ≤ 3.75 µg/mL. Treatment with TQ led to significant improvements in clinical scores, fungal burden, neutrophil infiltration, and the expression of inflammatory factors compared to the DMSO group. Moreover, TQ demonstrated the ability to reduce the levels of inflammatory factors in HCECs stimulated by C. albicans. Additionally, TQ enhanced the expressions of Nrf2 and HO-1 in mouse corneas. The downregulation of cytokines induced by TQ was reversed upon pretreatment with inhibitors of Nrf2 or HO-1.

CONCLUSION

TQ exhibits a protective effect in the context of C. albicans keratitis through multiple mechanisms, including inhibition of C. albicans growth, reduction of neutrophil recruitment, activation of the Nrf2/HO-1 pathway, and limitation of the expression of pro-inflammatory factors.

Antinociceptive Action of Thymoquinone-Loaded Liposomes in an In Vivo Model of Tendinopathy

Tendinopathies represent about 45% of musculoskeletal lesions and they are a big burden in clinics characterized by activity-related pain, focal tendon tenderness and intra-tendinous imaging changes. Many approaches have been proposed for tendinopathies' management (e.g., nonsteroidal anti-inflammatory drugs, corticosteroids, eccentric exercises, laser therapy), unfortunately with very little support of efficacy or serious side effects, thus making the identification of new treatments fundamental. The aim of the study was to test the protective and pain reliever effect of thymoquinone (TQ)-loaded formulations in a rat model of tendinopathy induced by carrageenan intra-tendon injection (20 µL of carrageenan 0.8% on day 1). Conventional (LP-TQ) and hyaluronic acid (HA)-coated TQ liposomes (HA-LP-TQ) were characterized and subjected to in vitro release and stability studies at 4 °C. Then, TQ and liposomes were peri-tendon injected (20 µL) on days 1, 3, 5, 7 and 10 to evaluate their antinociceptive profile using mechanical noxious and non-noxious stimuli (paw pressure and von Frey tests), spontaneous pain (incapacitance test) and motor alterations (Rota rod test). Liposomes containing 2 mg/mL of TQ and covered with HA (HA-LP-TQ2) reduced the development of spontaneous nociception and hypersensitivity for a long-lasting effect more than the other formulations. The anti-hypersensitivity effect matched with the histopathological evaluation. In conclusion, the use of TQ encapsulated in HA-LP liposomes is suggested as a new treatment for tendinopathies.

Thymoquinone Antifungal Activity against Candida glabrata Oral Isolates from Patients in Intensive Care Units-An In Vitro Study

The number of Candida spp. infections and drug resistance are dramatically increasing worldwide, particularly among immunosuppressed patients, and it is urgent to find novel compounds with antifungal activity. In this work, the antifungal and antibiofilm activity of thymoquinone (TQ), a key bioactive constituent of black cumin seed Nigella sativa L., was evaluated against Candida glabrata, a WHO 'high-priority' pathogen. Then, its effect on the expression of C. glabrata EPA6 and EPA7 genes (related to biofilm adhesion and development, respectively) were analyzed. Swab samples were taken from the oral cavity of 90 hospitalized patients in ICU wards, transferred to sterile falcon tubes, and cultured on Sabouraud Dextrose Agar (SDA) and Chromagar Candida for presumptive identification. Next, a 21-plex PCR was carried out for the confirmation of species level. C. glabrata isolates underwent antifungal drug susceptibility testing against fluconazole (FLZ), itraconazole (ITZ), amphotericin B (AMB), and TQ according to the CLSI microdilution method (M27, A3/S4). Biofilm formation was measured by an MTT assay. EPA6 and EPA7 gene expression was assessed by real-time PCR. From the 90 swab samples, 40 isolates were identified as C. glabrata with the 21-plex PCR. Most isolates were resistant to FLZ (n = 29, 72.5%), whereas 12.5% and 5% were ITZ and AMB resistant, respectively. The minimum inhibitory concentration (MIC₅₀) of TQ against C. glabrata was 50 µg/mL. Importantly, TQ significantly inhibited the biofilm formation of C. glabrata isolates, and EPA6 gene expression was reduced significantly at MIC₅₀ concentration of TQ. TQ seems to have some antifungal, antibiofilm (adhesion) effect on C. glabrata isolates, showing that this plant secondary metabolite is a promising agent to overcome Candida infections, especially oral candidiasis.

Experimental and Theoretical Insights on Chemopreventive Effect of the Liposomal Thymoquinone Against Benzo[a]pyrene-Induced Lung Cancer in Swiss Albino Mice

Purpose

Thymoquinone (TQ), a phytoconstituent of Nigella sativa seeds, has been studied extensively in various cancer models. However, TQ’s limited water solubility restricts its therapeutic applicability. Our work aims to prepare the novel formulation of TQ and assess its chemopreventive potential in chemically induced lung cancer animal model.

Methods

The polyethylene glycol coated DOPE/CHEMS incorporating TQ-loaded pH-sensitive liposomes (TQPSL) were prepared and characterized. Mice were exposed to benzo[a]pyrene (BaP) thrice a week for 4 weeks to induce lung cancer. TQPSL was administered three times a week for 21 weeks, starting 2 weeks before the first dose of BaP.

Results

The prepared TQPSL revealed 85% entrapment efficiency with 128 nm size and −19.5 mv ζ-potential showing high stability of the formulation. The pretreatment of TQPSL showed the recovery in BaP-modulated relative organ weight of lungs, cancer marker enzymes, and antioxidant enzymes in the serum. The histopathological analysis of the tissues showed that TQPSL protected the malignancy in the lungs. The flow cytometry data revealed the induction of apoptosis and decreased intracellular ROS by TQPSL. Molecular docking was performed to predict the TQ’s affinity for eight possible anticancer drug targets linked to lung cancer etiology. The data assisted to identify the serine/threonine-protein kinase BRAF as the most suitable target of TQ with binding energy −6.8 kcal/mol.

Conclusion

The current findings demonstrated the potential of TQPSL and its possible therapeutic targets of lung cancer. To our knowledge, this is the first research to outline the development of TQ formulation against lung cancer considering its low solubility as well as pulmonary delivery challenges.

Safety, Stability, and Therapeutic Efficacy of Long-Circulating TQ-Incorporated Liposomes: Implication in the Treatment of Lung Cancer

Thymoquinone (TQ), which is one of the main bioactive constituents of Nigella sativa seeds, has demonstrated its potential against various cancer models. The poor solubility of TQ in aqueous solution limits its uses in clinical application. The present study aimed to develop a novel formulation of TQ to increase its bioavailability and therapeutic potential with minimal toxicity. Polyethylene glycol (PEG)-coated DSPC/cholesterol comprising TQ liposomes (PEG-Lip-TQ) were prepared and characterized on various aspects. A computational investigation using molecular docking was used to assess the possible binding interactions of TQ with 12 prospective anticancer drug targets. The in vitro anticancer activity was assessed in A549 and H460 lung cancer cells in a time- and dose-dependent manner, while the oral acute toxicity assay was evaluated in silico as well as in vivo in mice. TQ docked to the Hsp90 target had the lowest binding energy of −6.05 kcal/mol, whereas caspase 3 was recognized as the least likely target for TQ with a binding energy of −1.19 kcal/mol. The results showed 96% EE with 120 nm size, and −10.85 mv, ζ-potential of PEG-Lip-TQ, respectively. The cell cytotoxicity data demonstrated high sensitivity of PEG-Lip-TQ and a several fold decrease in the IC₅₀ while comparing free TQ. The cell cycle analysis showed changes in the distribution of cells with doses. The in vivo data revealed an ~9-fold increase in the LD₅₀ of PEG-Lip-TQ on free TQ as an estimated 775 and 89.5 mg/kg b.w, respectively. This study indicates that the pharmacological and efficacy profile of PEG-lip-TQ is superior to free TQ, which will pave the way for an exploration of the effect of TQ formulation in the treatment of lung cancer in clinical settings.

Synergistic effect of thymoquinone and nystatin in the treatment of oral candidiasis; an in vitro study

The effectiveness of antifungal agents may be insufficient against resistant strains in some cases of oral candidiasis. The aim of this study was to evaluate the antifungal effect of thymoquinone against Candidaalbicans, Candidatropicalis, Candidaglabrata and Candidakrusei strains and the synergistic antifungal activity of these strains in combination with nystatin. To evaluate in vitro antifungal activity and interactions between thymoquinone and nystatin, substances were tested against Candidaalbicans ATCC 10,231, C.tropicalis ATCC 750, C.krusei ATCC 6258 and C.glabrata ATCC 2001 standard strains both individually and combinationally via microdilution method. MIC and ΣFIC index value were analysed. The Kruskal Wallis test and Bonferroni test were used for statistical evaluations. Statistical significance was set at p < 0.05. A statistically significant difference was observed between the mean ranks of all Candida species and doses of thymoquinone, nystatin, and the combination thymoquinone-nystatin (p < 0.05). MIC values for thymoquinone were determined as 15 μg/mL for C.albicans, C.tropicalis and C.krusei while it was 30 μg/mL for C.glabrata. Moreover, MIC for nystatin was found as 1.875 μg/mL for C.albicans, C.tropicalis and C.krusei, whereas it was 7.5 μg/mL in C. glabrata. Interaction assays and ΣFIC index value revealed that, TQ and nystatin have a synergistic effect against to all strains. Thymoquinone was found to have antifungal activity on Candida species and synergistic effect when combined with nystatin.

Safety and Therapeutic Efficacy of Thymoquinone-Loaded Liposomes against Drug-Sensitive and Drug-Resistant Acinetobacter baumannii

In the present study, we investigated the activity of free thymoquinone (TQ) or liposomal thymoquinone (Lip-TQ) in comparison to standard antibiotic amoxicillin (AMX) against the drug-sensitive and drug-resistant Acinetobacter baumannii. A liposomal formulation of TQ was prepared and characterized and its toxicity was evaluated by analyzing the hematological, liver and kidney function parameters. TQ was effective against both drug-sensitive and drug-resistant A. baumannii as shown by the findings of drug susceptibility testing and time kill kinetics. Moreover, the therapeutic efficacy of TQ or Lip-TQ against A. baumannii was assessed by the survival rate and the bacterial load in the lung tissues of treated mice. The mice infected with drug-sensitive A. baumannii exhibited a 90% survival rate on day 30 post treatment with Lip-TQ at a dose of 10 mg/kg, whereas the mice treated with AMX (10 mg/kg) had a 100% survival rate. On the other hand, the mice infected with drug-resistant A. baumannii had a 70% survival rate in the group treated with Lip-TQ, whereas AMX was ineffective against drug-resistant A. baumannii and all the mice died within day 30 after the treatment. Moreover, Lip-TQ treatment effectively reduced the bacterial load in the lung tissues of the mice infected with the drug-sensitive and drug-resistant A. baumannii. Moreover, the blood of the mice treated with Lip-TQ had reduced levels of inflammation markers, leukocytes and neutrophils. The results of the present study suggest that Lip-TQ may prove to be an effective therapeutic formulation in the treatment of the drug-sensitive or drug-resistant A. baumannii infection as well.

Coadministration of Ginger Extract and Fluconazole Shows a Synergistic Effect in the Treatment of Drug-Resistant Vulvovaginal Candidiasis

BACKGROUND

Azoles are the most common antifungal drugs used in the treatment of vulvovaginal candidiasis (VVC). The frequency of azole-resistant Candida isolates has increased dramatically in the last two decades. Here, we assessed the antifungal activity of a combination of fluconazole (FLZ) and methanolic extract of ginger (Meth-Gin) against drug-resistant vulvovaginal candidiasis (VVC) in a murine model.

METHODS

The in vitro activity of FLZ or a combination of FLZ and Meth-Gin was determined against Candida albicans by the agar well diffusion, macrodilution, time-kill and the biofilm eradication methods. The therapeutic efficacy of the formulations was assessed by analyzing the fungal load, pro-inflammatory cytokines, percent apoptotic cells and the histological changes in the vaginal tissues of the mice. Moreover, the renal toxicity the drug formulation was evaluated by analyzing the levels of the blood urea nitrogen (BUN) and creatinine.

RESULTS

The results of in vitro study demonstrated that FLZ did not show any activity against C. albicans, whereas a combination of FLZ and Meth-Gin demonstrated greater activity as shown by the data of the zone of growth inhibition, MIC and time-kill assay. FLZ or Meth-Gin treatment could not completely cure VVC, whereas a combination of FLZ and Meth-Gin was greatly effective in the treatment of VVC. The vaginal tissue from mice of the infected control group had the highest fungal load of 155370 ± 20617 CFUs. Treatment with FLZ at a dose of 40 mg/kg reduced the fungal load to 120863 ± 10723 CFUs. Interestingly, the mice treated with a combination of FLZ (40 mg/kg) and Meth-Gin (200 mg/kg) had a fungal load of 256 ± 152 CFUs. Besides, FLZ and Meth-Gin combination effectively reduced the pro-inflammatory cytokines (IL-1β, TNF-α and IL-17) and the percentage of apoptotic cells in the vaginal tissues. Likewise, the histological analysis revealed the epithelial necrosis, shedding and ulceration in the vaginal tissue, whereas treatment with FLZ and Meth-Gin combination reversed the histopathological changes in the vaginal epithelium and lamina propria.

CONCLUSION

The findings of the current study suggest that the co-administration of Meth-Gin and FLZ may have a potential therapeutic effect in the treatment of azole-resistant candidiasis.

Nanosystems against candidiasis: a review of studies performed over the last two decades

The crescent number of cases of candidiasis and the increase in the number of infections developed by non-albicans species and by multi-resistant strains has taken the attention of the scientific community, which has been searching for new therapeutic alternatives. Among the alternatives found the use of nanosystems for delivery of drugs already commercialized and new biomolecules have grown, in order to increase stability, solubility, optimize efficiency and reduce adverse effects. In view of the growing number of studies involving technological alternatives for the treatment of candidiasis, the present review came with the intention of gathering studies from the last two decades that used nanotechnology for the treatment of candidiasis, as well as analysing them critically and pointing out the future perspectives for their application with this purpose. Different studies were considered for the development of this review, addressing nanosystems such as metallic nanoparticles, mesoporous silica nanoparticles, polymeric nanoparticles, liposomes, nanoemulsion, microemulsion, solid lipid nanoparticle, nanostructured lipid carrier, lipidic nanocapsules and liquid crystals; and different clinical presentations of candidiasis. As a general overview, nanotechnology has proven to be an important ally for the treatment against the diversity of candidiasis found in the clinic, whether in increasing the effectiveness of commercialized drugs and reducing their adverse effects, as well as allowing exploring more effectively properties therapeutics of new biomolecules.

Potential of Methylglyoxal-Conjugated Chitosan Nanoparticles in Treatment of Fluconazole-Resistant Candida albicans Infection in a Murine Model

Background

Fungal infections are becoming more prevalent and threatening because of the continuous emergence of azole-resistant fungal infections. The present study was aimed to assess the activity of free Methylglyoxal (MG) or MG-conjugated chitosan nanoparticles (MGCN) against fluconazole-resistant Candida albicans.

Materials and Methods

A novel formulation of MGCN was prepared and characterized to determine their size, shape and polydispersity index. Moreover, the efficacy of fluconazole or MG or MGCN was determined against intracellular C. albicans in macrophages and the systematic candidiasis in a murine model. The safety of MG or MGCN was tested in mice by analyzing the levels of hepatic and renal toxicity parameters.

Results

Candida albicans did not respond to fluconazole, even at the highest dose of 20 mg/kg, whereas MG and MGCN effectively eliminated C. albicans from the macrophages and infected mice. Mice in the group treated with MGCN at a dose of 10 mg/kg exhibited a 90% survival rate and showed the lowest fungal load in the kidney, whereas the mice treated with free MG at the same dose exhibited 50% survival rate. Moreover, the administration of MG or MGCN did not induce any liver and kidney toxicity in the treated mice.

Conclusion

The findings of the present work suggest that MGCN may be proved a promising therapeutic formulation to treat azole-resistant C. albicans infections.

Nanocarriers: more than tour de force for thymoquinone

Introduction: Thymoquinone (TQ), 2-isopropyl-5-methylbenzo-1, 4-quinone, the main active constituent of Nigella sativa (NS) plant, has been proven to be of great therapeutic aid in various in vitro and in vivo conditions. Despite the promising therapeutic activities of TQ, this molecule is not yet in the clinical trials, restricted by its poor biopharmaceutical properties including photo-instability.Area covered: This review compiles the different types of polymeric and lipidic nanocarriers (NCs), encapsulating TQ for their improved oral bioavailability, and augmented in vitro and in vivo efficacy, evidenced on various pathologies. Furthermore, we provide a comprehensive overview of TQ in relation to its encapsulation approaches advancing the delivery and improving the efficacy of TQ.Expert opinion: TQ was first identified in the essential oil of Nigella sativa L. black seed. TQ has not been used in formulations because it is a highly hydrophobic drug having poor aqueous solubility. To deal with the poor physicochemical problems associated with TQ, various NCs encapsulating TQ have been tried in the past. Nevertheless, these NCs could be impending in bringing forth this potential molecule to clinical reality. This will also be beneficial for a large research community including pharmaceutical & biological sciences and translational researchers.

Tinospora cordifolia Aqueous Extract Alleviates Cyclophosphamide- Induced Immune Suppression, Toxicity and Systemic Candidiasis in Immunosuppressed Mice: In vivo Study in Comparison to Antifungal Drug Fluconazole

OBJECTIVE

The present study was aimed to evaluate the effect of the aqueous extract of Tinospora cordifolia (AETC) against cyclophosphamide-induced immunosuppression and systemic Candida albicans infection in a murine model.

METHODS

The protective effect of AETC against cyclophosphamide-induced leukopenia was evaluated by quantitative and qualitative analysis of the leukocytes. The immune-stimulating potential of AETC on macrophages was assessed by determining the levels of secreted cytokines. To determine the direct antifungal activity, AETC or fluconazole was administered to C. albicans infected mice. The efficacy of treatment was assessed by determining the survival rate, kidney fungal burden, the organ index and liver inflammation parameters.

RESULTS

Cyclophosphamide administration resulted in substantial depletion of leukocytes, whereas AETC treatment induced the recovery of leukocytes in cyclophosphamide-injected mice. Moreover, AETC treatment of macrophages resulted in enhanced secretion of IFN-γ, TNF-α and IL-1β. C. albicans infected mice treated with AETC at the doses of 50 and 100 mg/kg exhibited 40% and 60% survival rate, whereas the mice treated with fluconazole at a dose of 50 mg/kg showed 20% survival rate. Like survival data, the fungal load was found to be the lowest in the kidney tissues of mice treated with AETC at a dose of 100 mg/kg. Interestingly, mice infected with C. albicans demonstrated improvement in the organ indices and liver functioning after AETC treatment.

CONCLUSION

These results suggest that AETC may potentially be used to rejuvenate the weakened immune system and eliminate systemic candidiasis in mice.

Delivery of phytochemicals by liposome cargos: recent progress, challenges and opportunities

Bio-availability is a major concern in delivery of dietary phytochemicals for better bio-efficacy. The reduced bio-availability of food bioactive compounds is evident due to degradation during human digestion process which involves liberation, absorption, distribution, metabolism and elimination. The bio-efficacy of any nutrient can be increased by increasing bio-availability. Different technologies are available for engineered efficient delivery systems; still many challenges remain with advancement of delivery systems. The ease of preparedness and adaptability of liposomes has resulted in wide-range of applicability and acceptability in scientific field, especially as delivery vehicles. In view, of properties like biocompatibility and biodegradability, liposomes have been modified with different usable methodologies for delivery of phytochemicals. The aim of this review is to abridge liposomes, methods of preparation, their application as delivery cargo in dietary phytochemicals, result of using different preparation techniques on properties.

Thymoquinone Augments Cyclophosphamide-Mediated Inhibition of Cell Proliferation in Breast Cancer Cells

Objective:

Cancer chemotherapy at the recommended doses is largely associated with toxicity, and also it is not effective enough to reduce the advancement of the disease at lower doses. Thymoquinone (TQ) is an active compound derived from black seeds (Nigella sativa) which exhibits anticancer activities. The aim of the present study was to investigate the synergistic effect of TQ alone and in combination with cyclophosphamide (cyclo), and to unravel the role of TQ in fatty acid synthase (FASN) mediated molecular signaling in Her2 + and Her2- breast cancer cell lines.

Methods:

The effect of TQ on the growth of Her2+ SKBR-3 and Her2- MDA-231 breast cancer lines were evaluated as percent cell viability by cytotoxicity-based MTT assay. The analysis of cell cycle arrest was done through flow-cytometry followed by Western blot and RT-PCR to detect signaling events in the cells.

Results:

The data showed that TQ-cyclo (0.5mM-10µM) combination significantly inhibited the proliferation through the 5.49% and 57.72% accumulation of cells in sub-G1 and G1 respectively as 12% cells were shifted from G2/M phase in Her2+ breast cancer cells. Similarly, TQ-cyclo (0.5mM-20µM) combination exhibited that the 16.6% cells were arrested in Sub-G1 and only 3.54% cells were remained in G2/M phase as it was 22.89% in DMSO control in Her-2- breast cancers cells. Though TQ alone or in combination with cyclo alleviated the PI3K/Akt signaling by downregulating the phosphorylation of Akt and upregulating the PTEN, no changes was observed in FASN and Her-2 as well in both type of cells. The significant decreased expression of cyclin D1 was found in TQ-cyclo combinations.

Conclusion:

The current findings suggested that TQ can alter the cell cycle progression and induce cell death independent of FASN mediated signaling. In terms of clinical perspective, the present study clearly showed that TQ can broadly augment the effect of cyclo in breast cancer cases irrespective of Her-2+ or Her-.

Cyanosomes: A pilot study

Cyanobacteria are the most primitive, oxygen-evolving prokaryotic organism. Several, conspicuous investigations have been done around lipids from cyanobacteria. However, to date and to the best of our knowledge, no study was conducted to formulate and evaluate liposomal vesicles prepared from cyanobacterial lipid. In the present study, cyanosomes were formulated using natural lipids extracted from the cyanobacterium Synechococcus elongatus PCC7942 which were further loaded with thymoquinone. The results showed that the prepared cyanosomes were homogenous with an overall negative charge of particle size ranging between 200 to 210 nm and entrapment efficacy was 70.9 ± 1.86%. The obtained release profiles demonstrated sustained drug release pattern. The study of encapsulated thymoquinone on CCl₄ induced liver insult in balb/c mice revealed the better efficacy of encapsulated thymoquinone as compared to thymoquinone alone indicating cyanosome as a promising candidate for drug carrier. However, more studies are required to establish the safety profile, pharmacokinetic pattern and biodistribution parameters of cyanosome for its clinical intricacies in future applications.

Thymoquinone (TQ) inhibits the replication of intracellular Mycobacterium tuberculosis in macrophages and modulates nitric oxide production

Background

Human tuberculosis, which is caused by the pathogen Mycobacterium tuberculosis, remains a major public health concern. Increasing drug resistance poses a threat of disease resurgence and continues to cause considerable mortality worldwide, which necessitates the development of new drugs with improved efficacy. Thymoquinone (TQ), an essential compound of Nigella sativa, was previously reported as an active anti-tuberculosis agent.

Methods

In this study, the effects of TQ on intracellular mycobacterial replication are examined in macrophages. In addition, its effect on mycobacteria-induced NO production and pro-inflammatory responses were investigated in Mycobacterium tuberculosis (MTB)-infected Type II human alveolar and human myeloid cell lines.

Results

TQ at concentrations ranging from 12.5 to 25 μg/mL and 6.25 to 12.5 μg/mL reduced intracellular M. tuberculosis H37Rv and extensively drug-resistant tuberculosis (XDR-TB) 72 h post-infection in RAW 264.7 cells. TQ treatment also produced a concentration-dependent reduction in nitric oxide production in both H37Rv and XDR-TB infected RAW 264.7 cells. Furthermore, TQ reduced the expression of inducible nitric oxide synthase (iNOS) and pro-inflammatory molecules such as tumor necrosis factor-alpha (TNF-α) and interlukin-6 (IL-6) in H37Rv-infected cells and eventually reduced pathogen-derived stress in host cells.

Conclusions

TQ inhibits intracellular H37Rv and XDR-TB replication and MTB-induced production of NO and pro-inflammatory molecules. Therefore, along with its anti-inflammatory effects, TQ represents a prospective treatment option to combat Mycobacterium tuberculosis infection.

Thymoquinone binds and activates human salivary aldehyde dehydrogenase: Potential therapy for the mitigation of aldehyde toxicity and maintenance of oral health

Human salivary aldehyde dehydrogenase (hsALDH) is a very important anti-oxidant enzyme present in the saliva. It is involved in the detoxification of toxic aldehydes and maintenance of oral health. Reduced level of hsALDH activity is a risk factor for oral cancer development. Thymoquinone (TQ) has many pharmacological activities and health benefits. This study aimed to examine the activation of hsALDH by TQ. The effect of TQ on the activity and kinetics of hsALDH was studied. The binding of TQ with the enzyme was examined by different biophysical methods and molecular docking analysis. TQ enhanced the dehydrogenase activity of crude and purified hsALDH by 3.2 and 2.9 fold, respectively. The K_m of the purified enzyme decreased and the V_max increased. The esterase activity also increased by 1.2 fold. No significant change in the nucleophilicity of the catalytic cysteine residue was observed. TQ forms a strong complex with hsALDH without altering the secondary structures of the enzyme. It fits in the active site of ALDH3A1 close to Cys 243 and the other highly conserved amino acid residues which lead to enhancement of substrate binding affinity and catalytic efficiency of the enzyme. TQ is expected to give better protection from toxic aldehydes in the oral cavity and to reduce the risk of oral cancer development through the activation of hsALDH. Therefore, the addition of TQ in the diet and other oral formulations is expected to be beneficial for health.

Oral bioavailability enhancement and hepatoprotective effects of thymoquinone by self-nanoemulsifying drug delivery system

Thymoquinone (TQ) is a poorly water soluble bioactive compound which shows poor oral bioavailability upon oral administration. Due to poor aqueous solubility and bioavailability of TQ, various self-nanoemulsifying drug delivery systems (SNEDDS) of TQ were developed and evaluated for enhancement of its hepatoprotective effects and oral bioavailability. Hepatoprotective and pharmacokinetic studies of TQ suspension and TQ-SNEDDS were carried out in rat models. Different SNEDDS formulations of TQ were developed and thermodynamically stable TQ-SNEDDS were characterized for physicochemical parameters and evaluated for drug release studies via dialysis membrane. Optimized SNEDDS formulation of TQ was selected for further evaluation of in vivo evaluation. In vivo hepatoprotective investigations showed significant hepatoprotective effects for optimized TQ-SNEDDS in comparison with TQ suspension. The oral administration of optimized SNEDDS showed significant improvement in in vivo absorption of TQ in comparison with TQ suspension. The relatively bioavailability of TQ was enhanced 3.87-fold by optimized SNEDDS in comparison with TQ suspension. The results of this research work indicated the potential of SNEDDS in enhancing relative bioavailability and therapeutic effects of natural bioactive compounds such as TQ.

Thymoquinone, an active constituent of Nigella sativa seeds, binds with bilirubin and protects mice from hyperbilirubinemia and cyclophosphamide-induced hepatotoxicity

Some reports indicate that thymoquinone (TQ), the main constituent of Nigella sativa seeds, is hepatoprotective. The aim of this study was to determine whether TQ is able to bind directly to bilirubin, and whether TQ or liposomal formulation of TQ (Lip-TQ) can reduce cyclophosphamide (CYP)-induced liver toxicity, serum bilirubin level in mice. The binding of TQ with bilirubin was studied by UV-VIS, fluorescence and Near-UV CD spectroscopy. Inhibition of binding of bilirubin to erythrocytes by TQ was also examined. To increase the in vivo efficacy, Lip-TQ was prepared and used against CYP-induced toxicity. The protective role of TQ or Lip-TQ against CYP-induced toxicity was assessed by determining the liver function parameters, the levels of superoxide dismutase (SOD) and catalase (CAT), and histological studies. It was found that TQ binds to bilirubin and significantly inhibits the binding of bilirubin to erythrocytes. Lip-TQ (10 mg/kg) significantly reduced the levels of aspartate transaminase (AST) from 254 ± 48 to 66 ± 18 IU/L (P < 0.001), alanine transaminase (ALT) from 142 ± 28 to 47.8 ± 16 IU/L (P < 0.05) and serum bilirubin from 2.8 ± 0.50 to 1.24 ± 0.30 mg/dl (P < 0.05). Treatment with Lip-TQ reduced the CYP-induced inflammation and hemorrhage in liver tissues. Moreover, treatment with free or Lip-TQ protected the activity of SOD and CAT in CYP-injected mice. Therefore, TQ can reduce the level of bilirubin in systemic circulation in disease conditions that lead to hyperbilirubinemia and liver toxicity and hence may be used as a supplement in the treatment of liver ailments.