Molecular Therapies for Inherited Retinal Diseases-Current Standing, Opportunities and Challenges

Inherited retinal diseases (IRDs) are both genetically and clinically highly heterogeneous and have long been considered incurable. Following the successful development of a gene augmentation therapy for biallelic RPE65-associated IRD, this view has changed. As a result, many different therapeutic approaches are currently being developed, in particular a large variety of molecular therapies. These are depending on the severity of the retinal degeneration, knowledge of the pathophysiological mechanism underlying each subtype of IRD, and the therapeutic target molecule. DNA therapies include approaches such as gene augmentation therapy, genome editing and optogenetics. For some genetic subtypes of IRD, RNA therapies and compound therapies have also shown considerable therapeutic potential. In this review, we summarize the current state-of-the-art of various therapeutic approaches, including the pros and cons of each strategy, and outline the future challenges that lie ahead in the combat against IRDs.

Contact lenses as drug-delivery systems: a promising therapeutic tool

The ocular administration of drugs using traditional pharmaceutical forms, including eye drops or ointments, results in low bioavailability, as well as requiring multiple administrations per day, with the consequent danger of therapeutic non-compliance. Although, through the use of pharmaceutical technology, attempts have been made to use various solutions in order to increase bioavailability in the most common pharmaceutical forms, it has not been entirely satisfactory. In this context, contact lenses are presented as drug delivery systems that largely remedy these two major problems and offer other additional advantages. Therefore, the use of contact lenses as drug carrying systems has been increasingly investigated in recent years, as they can increase the bioavailability of these drugs, leading to an increase in therapeutic efficacy and compliance. The main techniques used to achieve this goal are included in this review, including immersion in drug solutions, use of vitamin E barriers, molecular printing, colloidal systems, etc. The most interesting results, depending on the different eye pathologies, are presented. Although the use of contact lenses as a vehicle for the release of active ingredients is a relatively novel strategy, there are already many studies and trials that support it. In any case, further research needs to be carried out to finally reach an effective, safe, and stable product that can be marketed.

Advances in Biodegradable Nano-Sized Polymer-Based Ocular Drug Delivery

The effective delivery of drugs to the eye remains a challenge. The eye has a myriad of defense systems and physiological barriers that leaves ocular drug delivery systems with low bioavailability profiles. This is mainly due to poor permeability through the epithelia and rapid clearance from the eye following administration. However, recent advances in both polymeric drug delivery and biomedical nanotechnology have allowed for improvements to be made in the treatment of ocular conditions. The employment of biodegradable polymers in ocular formulations has led to improved retention time, greater bioavailability and controlled release through mucoadhesion to the epithelia in the eye, amongst other beneficial properties. Nanotechnology has been largely investigated for uses in the medical field, ranging from diagnosis of disease to treatment. The nanoscale of these developing drug delivery systems has helped to improve the penetration of drugs through the various ocular barriers, thus improving bioavailability. This review will highlight the physiological barriers encountered in the eye, current conventional treatment methods as well as how polymeric drug delivery and nanotechnology can be employed to optimize drug penetration to both the anterior and posterior segment of the eye.

Gene Expression Profiling Analysis Reveals Putative Phytochemotherapeutic Target for Castration-Resistant Prostate Cancer

Prostate cancer is the leading cause of cancer death among men globally, with castration development resistant contributing significantly to treatment failure and death. By analyzing the differentially expressed genes between castration-induced regression nadir and castration-resistant regrowth of the prostate, we identified soluble guanylate cyclase 1 subunit alpha as biologically significant to driving castration-resistant prostate cancer. A virtual screening of the modeled protein against 242 experimentally-validated anti-prostate cancer phytochemicals revealed potential drug inhibitors. Although, the identified four non-synonymous somatic point mutations of the human soluble guanylate cyclase 1 gene could alter its form and ligand binding ability, our analysis identified compounds that could effectively inhibit the mutants together with wild-type. Of the identified phytochemicals, (8′R)-neochrome and (8′S)-neochrome derived from the Spinach (Spinacia oleracea) showed the highest binding energies against the wild and mutant proteins. Our results identified the neochromes and other phytochemicals as leads in pharmacotherapy and as nutraceuticals in management and prevention of castration-resistance prostate cancers.

Human MRP2 exports MC-LR but not the glutathione conjugate

Water contamination by cyanobacterial blooms is a worldwide health hazard to humans as well as livestock. Exposure to Microcystins (MCs), toxins produced by various cyanobacterial or blue green algae found in poorly treated drinking water or contaminated seafood such as fish or prawns are associated with hepatotoxicity, nephropathy and neurotoxicity and in extreme cases, death in humans. MC congeners, currently >240 known, differ dramatically in their uptake kinetics, i.e. their uptake via OATP1B1 and OATP1B3, in OATP overexpressing human HEK293 cells and primary human hepatocytes. It is thus likely that MC congeners will also differ with respect to the cellular efflux of the parent and conjugated congeners, e.g. via MRPs, MDRs, BCRP or BSEP. Consequently, the role and kinetics of different human efflux transporters - MRP, MDR, BCRP and BSEP in MC efflux was studied using insect membrane vesicles overexpressing the human transporters of interest. Of the efflux transporters investigated, MRP2 displayed MC transport. Michaelis-Menten kinetics displayed mild co-operativity and thus allosteric behavior of MRP2. MC transport by MRP2 was MC congener-specific, whereby MC-LF was transported more rapidly than MC-LR and -RR. Other human transporters (BCRP, BSEP, MRP1,3,5, MDR1) tested in this study did not exhibit interaction with MC. Although MRP2 showed specific MC transport, the MC-LR-GSH conjugate, was not transported suggesting the involvement of other transporters than MRP2 for the conjugate efflux.

Nanoparticles for ocular drug delivery: modified and non-modified chitosan as a promising biocompatible carrier

The eye is a very important, yet sensitive organ, presenting complex anatomy. To overcome its protective mechanisms, with the aim of improving drug delivery, drug encapsulation in nanocarriers is considered in this review. Chitosan is found to be an excellent drug carrier and its application in ophthalmology is being extensively researched. This mucoadhesive biopolymer can protect the encapsulated molecule, optimize its mode of action and minimize any existent risk. Moreover, chitosan and its derivatives may provide advantageous properties to the system such as thermoresponsivity and pH dependency. Finally, dual systems of chitosan with other carriers, such as poly (lactic-co-glycolic acid) and alginate, are also mentioned in this review, as they may offer additional benefits such as higher permeation due to different interaction of each carrier with the corneal layers.

Exploring the pharmacological effects and potential targets of paeoniflorin on the endometriosis of cold coagulation and blood stasis model rats by ultra-performance liquid chromatography tandem mass spectrometry with a pattern recognition approach

This study was employed to explore the potential biomarkers of endometriosis of cold coagulation and blood stasis (ECB) model rats and the effective mechanism of action of paeoniflorin (PF). The serum metabolomics approach was carried out using the UPLC-MS technique with a pattern recognition approach to prove the possible biomarkers of the ECB model rats and the perturbed pathways. Subsequently, the mechanism of PF treatment of this disease model was elucidated. The results revealed that the serum metabolism profiles in two groups were also separated significantly. Moreover, 8 biomarkers were found in the positive mode, and 5 biomarkers were found in the negative mode. Totally, 13 biomarkers participated in the metabolism of phenylalanine, arachidonic acid, etc. After treatment with PF, 10 biomarkers were regulated. Among the 10 biomarkers, 4 were statistically significant: l-phenylalanine, l-tryptophan, LysoPC (18:4(6Z,9Z,12Z,15Z)), and LysoPC (16:1(9Z)). We initially confirmed that PF could significantly regulate the metabolic expression of multiple metabolic pathways in the ECB model rats. For the first time, this study explored the mechanism of action of PF treatment based on the metabolic pathways of the organism and demonstrated the potential of the metabolomics techniques for the study of drug action mechanisms.

Current Approaches to Use Cyclodextrins and Mucoadhesive Polymers in Ocular Drug Delivery—A Mini-Review

Ocular drug delivery provides a challenging opportunity to develop optimal formulations with proper therapeutic effects and acceptable patient compliance because there are many restricting factors involved, such as complex anatomical structures, defensive mechanisms, rapid drainage, and applicability issues. Fortunately, recent advances in the field mean that these problems can be overcome through the formulation of innovative ophthalmic products. Through the addition of solubility enhancer cyclodextrin derivatives and mucoadhesive polymers, the permeability of active ingredients is improved, and retention time is increased in the ocular surface. Therefore, preferable efficacy and bioavailability can be achieved. In this short review, the authors describe the theoretical background, technological possibilities, and the current approaches in the field of ophthalmology.

Non-Lamellar Lyotropic Liquid Crystalline Lipid Nanoparticles for the Next Generation of Nanomedicine

Nonlamellar lyotropic liquid crystalline (LLC) lipid nanomaterials have emerged as a promising class of advanced materials for the next generation of nanomedicine, comprising mainly of amphiphilic lipids and functional additives self-assembling into two- and three-dimensional, inverse hexagonal, and cubic nanostructures. In particular, the lyotropic liquid crystalline lipid nanoparticles (LCNPs) have received great interest as nanocarriers for a variety of hydrophobic and hydrophilic small molecule drugs, peptides, proteins, siRNAs, DNAs, and imaging agents. Within this space, there has been a tremendous amount of effort over the last two decades elucidating the self-assembly behavior and structure-function relationship of natural and synthetic lipid-based drug delivery vehicles in vitro, yet successful clinical translation remains sparse due to the lack of understanding of these materials in biological bodies. This review provides an overview of (1) the benefits and advantages of using LCNPs as drug delivery nanocarriers, (2) design principles for making LCNPs with desirable functionalities for drug delivery applications, (3) current understanding of the LLC material-biology interface illustrated by more than 50 in vivo, preclinical studies, and (4) current patenting and translation activities in a pharmaceutical context. Together with our perspectives and expert opinions, we anticipate that this review will guide future studies in developing LCNP-based drug delivery nanocarriers with the objective of translating them into a key player among nanoparticle platforms comprising the next generation of nanomedicine for disease therapy and diagnosis.

Health Benefits of Endurance Training: Implications of the Brain-Derived Neurotrophic Factor-A Systematic Review

This article presents a concept that wide expression of brain-derived neurotrophic factor (BDNF) and its receptors (TrkB) in the nervous tissue, evoked by regular endurance training (ET), can cause numerous motor and metabolic adaptations, which are beneficial for human health. The relationships between the training-evoked increase of endogenous BDNF and molecular and/or physiological adaptations in the nervous structures controlling both motor performance and homeostasis of the whole organism have been presented. Due to a very wide range of plastic changes that ET has exerted on various systems of the body, the improvement of motor skills and counteraction of the development of civilization diseases resulting from the posttraining increase of BDNF/TrkB levels have been discussed, as important for people, who undertake ET. Thus, this report presents the influence of endurance exercises on the (1) transformation of motoneuron properties, which are a final element of the motor pathways, (2) reduction of motor deficits evoked by Parkinson disease, and (3) prevention of the metabolic syndrome (MetS). This review suggests that the increase of posttraining levels of BDNF and its TrkB receptors causes simultaneous changes in the activity of the spinal cord, the substantia nigra, and the hypothalamic nuclei neurons, which are responsible for the alteration of the functional properties of motoneurons innervating the skeletal muscles, for the enhancement of dopamine release in the brain, and for the modulation of hormone levels involved in regulating the metabolic processes, responsively. Finally, training-evoked increase of the BDNF/TrkB leads to a change in a manner of regulation of skeletal muscles, causes a reduction of motor deficits observed in the Parkinson disease, and lowers weight, glucose level, and blood pressure, which accompany the MetS. Therefore, BDNF seems to be the molecular factor of pleiotropic activity, important in the modulation processes, underlying adaptations, which result from ET.

Ocular Drug Delivery: A Special Focus on the Thermosensitive Approach

The bioavailability of ophthalmic therapeutics is reduced because of the presence of physiological barriers whose primary function is to hinder the entry of exogenous agents, therefore also decreasing the bioavailability of locally administered drugs. Consequently, repeated ocular administrations are required. Hence, the development of drug delivery systems that ensure suitable drug concentration for prolonged times in different ocular tissues is certainly of great importance. This objective can be partially achieved using thermosensitive drug delivery systems that, owing to their ability of changing their state in response to temperature variations, from room to body temperature, may increase drug bioavailability. In the case of topical instillation, in situ forming gels increase pre-corneal drug residence time as a consequence of their enhanced adhesion to the corneal surface. Otherwise, in the case of intraocular and periocular, i.e., subconjunctival, retrobulbar, peribulbar administration, among others, they have the undoubted advantage of being easily injectable and, owing to their sudden thickening at body temperature, have the ability to form an in situ drug reservoir. As a result, the frequency of administration can be reduced, also favoring the patient’s adhesion to therapy. In the main section of this review, we discuss some of the most common treatment options for ocular diseases, with a special focus on posterior segment treatments, and summarize the most recent improvement deriving from thermosensitive drug delivery strategies. Aside from this, an additional section describes the most widespread in vitro models employed to evaluate the functionality of novel ophthalmic drug delivery systems.

Current Trends and Future Perspective of Mesenchymal Stem Cells and Exosomes in Corneal Diseases

The corneal functions (transparency, refractivity and mechanical strength) deteriorate in many corneal diseases but can be restored after corneal transplantation (penetrating and lamellar keratoplasties). However, the global shortage of transplantable donor corneas remains significant and patients are subject to life-long risk of immune response and graft rejection. Various studies have shown the differentiation of multipotent mesenchymal stem cells (MSCs) into various corneal cell types. With the unique properties of immunomodulation, anti-angiogenesis and anti-inflammation, they offer the advantages in corneal reconstruction. These effects are widely mediated by MSC differentiation and paracrine signaling via exosomes. Besides the cell-free nature of exosomes in circumventing the problems of cell-fate control and tumorigenesis, the vesicle content can be genetically modified for optimal therapeutic affinity. The pharmacology and toxicology, xeno-free processing with sustained delivery, scale-up production in compliant to Good Manufacturing Practice regulations, and cost-effectiveness are the current foci of research. Routes of administration via injection, topical and/or engineered bioscaffolds are also explored for its applicability in treating corneal diseases.

Investigations on Polymeric Nanoparticles for Ocular Delivery

In the present investigation, an attempt was made to formulate timolol maleate (TML) loaded polymeric nanoparticles of flax seed gum (FX) and chitosan (CH) for ocular delivery using ionic gelation method. The process of nanoparticle preparation was optimized using 2-factor, 3-level central composite experimental design. The optimal concentration of FX and CH that yielded nanoparticles with minimum particle size (267.06 ± 8.65 nm) and maximum encapsulation efficiency (74.96 ± 4.78%) was found to be 0.10% w/v and 0.08% w/v, respectively. The formulated nanoparticles revealed considerable bioadhesive strength and exhibited sustained release of drug in in vitro diffusion studies. The ex vivo transcorneal penetration study revealed higher corneal penetration of TML compared to marketed eye drops. The confocal scanning laser microscopy (CSLM) studies also confirmed the ability of nanoparticles to penetrate into deeper layers of cornea. The histopathological studies revealed corneal biocompatibility of nanoparticles. The nanoparticles were found to reduce the intra ocular pressure (IOP) in rabbits for prolonged period when compared to conventional eye drops. The results of the present study suggested a promising role of polymeric nanoparticles for ocular drug delivery in treatment of glaucoma.

Optimizing live-animal bioluminescence imaging prediction of tumor burden in human prostate cancer xenograft models in SCID-NSG mice

BACKGROUND

Noninvasive live-animal longitudinal monitoring of xenograft tumor growth and metastasis by bioluminescent imaging (BLI) has been widely reported in cancer biology and preclinical therapy literature, mainly in athymic nude mice. Our own experience at calibrating BLI readout with tumor weight/volume in human prostate cancer xenograft models in haired, SCID-NSG mice through intraprostatic (orthotopic) and subcutaneous (SC) inoculations revealed either nonexistent or poor correlation (coefficient of determination, R ²  = ~0.01-0.3). The present work examined several technical and biological factors to improve BLI utility.

METHODS

After ruling out promoter-luciferase (luc) specificity and luc gene loss in the cell inoculum with LNCaP-AR-luc cells expressing an androgen receptor (AR) and tagged with AR-responsive probasin promoter-luc gene, we evaluated different routes of d-luciferin administration, imaging time during the day, charge-coupled device camera image acquisition settings, and hair removal methods to improve the imaging protocol. For most imaging sessions, BLI was carried out within the same day of tumor volume measurement. After necropsy, histological and immunohistochemical (IHC) analyses were performed on the tumors to evaluate necrosis and expression of luciferase and AR, respectively.

RESULTS

Injection of d-luciferin by SC route, robust image-capture setting (30 000 counts and autoexposure), imaging in the morning and thorough hair removal resulted in a substantial improvement of R² to ~0.6. Histological analyses confirmed the lack of BLI signal in necrotic tumor masses consistent with luciferase-mediated light emission only in oxygenated adenosine triphosphate-producing viable cells. IHC staining detected heterogeneous expression of luciferase tracking generally with AR expression in nonnecrotic tumor tissues.

CONCLUSIONS

Our body of work highlighted a framework to validate imaging protocols to ensure the acquisition of interpretable BLI data as an indicator of xenograft tumor burden. The vast tissue heterogeneity in prostate tumor xenografts and variable luciferase expression constrained this technology from achieving a high correlation.

Higher adalimumab serum levels do not increase the risk of adverse events in patients with inflammatory bowel disease

Background: The relationship between serum adalimumab concentrations and adverse events in patients with inflammatory bowel disease (IBD) is unknown. We aimed to determine whether patients with IBD using adalimumab are at increased risk of adverse events if they have higher adalimumab serum levels compared to those with lower adalimumab levels. Methods: This was a retrospective study of 191 IBD patients with at least one serum adalimumab level measurement available. The cohort was divided using a cutoff level of 10 mcg/mL. The primary outcome was the rate of overall adverse events between the two groups. Secondary outcomes included rate of infections, dermatologic reactions, injection-site reactions and other adverse events in both groups. Rates of discontinuation of adalimumab due to adverse events were evaluated. Multivariate logistic regression analysis was performed to evaluate the relationship between adalimumab levels and adverse events. Results: A total of 41 adverse events were reported in 191 patients in the overall cohort. Among 86 patients with higher adalimumab levels, 22 adverse events were reported, vs. 19 adverse events among 105 patients with lower adalimumab levels (25.6% vs. 18.1%, p = .21). Analysis according to adalimumab level tertiles also did not show significant differences in the rates of adverse events. A multivariate forward selection model also did not find higher odds of an adverse event in IBD patients with higher adalimumab levels compared to lower levels (OR 1.54, 95% CI 0.77-3.08). Conclusions: There does not appear to be a relationship between adalimumab exposure and risk of adverse events in IBD patients.

Ocular Biodistribution Studies using Molecular Imaging

Classical methodologies used in ocular pharmacokinetics studies have difficulties to obtain information about topical and intraocular distribution and clearance of drugs and formulations. This is associated with multiple factors related to ophthalmic physiology, as well as the complexity and invasiveness intrinsic to the sampling. Molecular imaging is a new diagnostic discipline for in vivo imaging, which is emerging and spreading rapidly. Recent developments in molecular imaging techniques, such as positron emission tomography (PET), single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI), allow obtaining reliable pharmacokinetic data, which can be translated into improving the permanence of the ophthalmic drugs in its action site, leading to dosage optimisation. They can be used to study either topical or intraocular administration. With these techniques it is possible to obtain real-time visualisation, localisation, characterisation and quantification of the compounds after their administration, all in a reliable, safe and non-invasive way. None of these novel techniques presents simultaneously high sensitivity and specificity, but it is possible to study biological procedures with the information provided when the techniques are combined. With the results obtained, it is possible to assume that molecular imaging techniques are postulated as a resource with great potential for the research and development of new drugs and ophthalmic delivery systems.

Therapeutic implications of nanomedicine for ocular drug delivery

Delivering therapeutics to the eye is challenging on multiple levels: rapid clearance of eyedrops from the ocular surface requires frequent instillation, which is difficult for patients; transport of drugs across the blood-retinal barrier when drugs are administered systemically, and the cornea when drugs are administered topically, is difficult to achieve; limited drug penetration to the back of the eye owing to the cornea, conjunctiva, sclera and vitreous barriers. Nanomedicine offers many advantages over conventional ophthalmic medications for effective ocular drug delivery because nanomedicine can increase the therapeutic index by overcoming ocular barriers, improving drug-release profiles and reducing potential drug toxicity. In this review, we highlight the therapeutic implications of nanomedicine for ocular drug delivery.

Nanoemulsion Based Vehicle for Effective Ocular Delivery of Moxifloxacin Using Experimental Design and Pharmacokinetic Study in Rabbits

Nanoemulsion is one of the potential drug delivery strategies used in topical ocular therapy. The purpose of this study was to design and optimize a nanoemulsion-based system to improve therapeutic efficacy of moxifloxacin in ophthalmic delivery. Moxifloxacin nanoemulsions were prepared by testing their solubility in oil, surfactants, and cosurfactants. A pseudoternary phase diagram was constructed by titration technique and nanoemulsions were obtained with four component mixtures of Tween 80, Soluphor^® P, ethyl oleate and water. An experiment with simplex lattice design was conducted to assess the influence of formulation parameters in seven nanoemulsion formulations (MM1–MM7) containing moxifloxacin. Physicochemical characteristics and in vitro release of MM1–MM7 were examined and optimized formulation (MM3) was further evaluated for ex vivo permeation, antimicrobial activity, ocular irritation and stability. Drug pharmacokinetics in rabbit aqueous humor was assessed for MM3 and compared with conventional commercial eye drop formulation (control). MM3 exhibited complete drug release in 3 h by Higuchi diffusion controlled mechanism. Corneal steady state flux of MM3 (~32.01 µg/cm²/h) and control (~31.53 µg/cm²/h) were comparable. Ocular irritation study indicated good tolerance of MM3 and its safety for ophthalmic use. No significant changes were observed in the physicochemical properties of MM3 when stored in the refrigerator for 3 months. The greater aqueous humor concentration (C_max; 555.73 ± 133.34 ng/mL) and delayed T_max value (2 h) observed in MM3 suggest a reduced dosing frequency and increased therapeutic efficacy relative to control. The area under the aqueous humor concentration versus time curve (AUC_{0–8 h}) of MM3 (1859.76 ± 424.51 ng·h/mL) was ~2 fold higher (p < 0.0005) than the control, suggesting a significant improvement in aqueous humor bioavailability. Our findings suggest that optimized nanoemulsion (MM3) enhanced the therapeutic effect of moxifloxacin and can therefore be used as a safe and effective delivery vehicle for ophthalmic therapy.

Recent Trends in Advanced Contact Lenses

Exploiting contact lenses for ocular drug delivery is an emerging field in the area of biomedical engineering and advanced healthcare materials. Despite all the research conducted in this area, still, new technologies are in their early stages of the development, and more work must be done in terms of clinical trials to commercialize these technologies. A great challenge in using contact lenses for drug delivery is to achieve a prolonged drug release profile within the therapeutic range for various eye-related problems and diseases. In general, desired release kinetics to avoid the initial burst release is the zero-order kinetics within the therapeutic range. This review highlights the new technologies developed to achieve efficient and extended drug delivery. It also provides an overview of the materials and methods for fabrication of contact lenses and their mechanical and optical properties.

Evaluating the Efficacies of Carbapenem/β-Lactamase Inhibitors Against Carbapenem-Resistant Gram-Negative Bacteria in vitro and in vivo

Background

Carbapenem-resistant Gram-negative bacteria are a major clinical concern as they cause virtually untreatable infections since carbapenems are among the last-resort antimicrobial agents. β-Lactamases implicated in carbapenem resistance include KPC, NDM, and OXA-type carbapenemases. Antimicrobial combination therapy is the current treatment approach against carbapenem resistance in order to limit the excessive use of colistin; however, its advantages over monotherapy remain debatable. An alternative treatment strategy would be the use of carbapenem/β-lactamase inhibitor (βLI) combinations. In this study, we assessed the in vitro and in vivo phenotypic and molecular efficacies of three βLIs when combined with different carbapenems against carbapenem-resistant Gram-negative clinical isolates. The chosen βLIs were (1) Avibactam, against OXA-type carbapenemases, (2) calcium-EDTA, against NDM-1, and (3) Relebactam, against KPC-2.

Methods

Six Acinetobacter baumannii clinical isolates were screened for bla _OXA-23-like, bla _OXA-24/40, bla _OXA-51-like, bla _OXA-58, and bla _OXA-143-like, and eight Enterobacteriaceae clinical isolates were screened for bla _OXA-48, bla _NDM-1, and bla _KPC-2. The minimal inhibitory concentrations of Imipenem (IPM), Ertapenem (ETP), and Meropenem (MEM) with corresponding βLIs for each isolate were determined. The efficacy of the most suitable in vitro treatment option against each of bla _OXA-48, bla _NDM-1, and bla _KPC-2 was assessed via survival studies in a BALB/c murine infection model. Finally, RT-qPCR was performed to assess the molecular response of the genes of resistance to the carbapenem/βLI combinations used under both in vitro and in vivo settings.

Results

Combining MEM, IPM, and ETP with the corresponding βLIs restored the isolates' susceptibilities to those antimicrobial agents in 66.7%, 57.1%, and 30.8% of the samples, respectively. Survival studies in mice revealed 100% survival rates when MEM was combined with either Avibactam or Relebactam against bla _OXA-48 and bla _KPC-2, respectively. RT-qPCR demonstrated the consistent overexpression of bla _OXA-48 upon treatment, without hindering Avibactam's activity, while bla _NDM-1 and bla _KPC-2 experienced variable expression levels upon treatment under in vitro and in vivo settings despite their effective phenotypic results.

Conclusion

New carbapenem/βLI combinations may be viable alternatives to antimicrobial combination therapy as they displayed high efficacy in vitro and in vivo. Meropenem/Avibactam and Meropenem/Relebactam should be tested on larger sample sizes with different carbapenemases before progressing further in its preclinical development.

Drug interactions of dipeptidyl peptidase 4 inhibitors involving CYP enzymes and P-gp efflux pump

Dipeptidyl peptidase 4 (DPP4) inhibitors are oral antidiabetic drugs approved to manage type 2 diabetes mellitus. Saxagliptin is a substrate of CYP3A4/5 enzymes while other DPP4 inhibitors such as sitagliptin, linagliptin, gemigliptin and teneligliptin are weak substrates of CYP3A4. DPP4 inhibitors have also been identified as substrates of P-gp. Hence, the drugs inhibiting or inducing CYP3A4/5 enzymes and/or P-gp can alter the pharmacokinetics of DPP4 inhibitors. This review is aimed to identify the drugs interacting with DPP4 inhibitors. The plasma concentrations of saxagliptin have been reported to be increased significantly by the concomitant administration of ketoconazole or diltiazem while no significant interactions between various DPP4 inhibitors and drugs like warfarin, digoxin or cyclosporine have been identified.

Contact Lens Based Drug Delivery to the Posterior Segment Via Iontophoresis in Cadaver Rabbit Eyes

PURPOSE

A drug loaded contact lens combined with electrodes positioned diametrically opposite and beyond the limbus can potentially deliver ionic drugs directly to the vitreous.

METHODS

Commercial lenses are loaded with nile blue or fluorescein as the drug analogs and placed on cadaver rabbit eyes. Electrodes (19.6 mm²) are placed atop at opposite sides of the sclera to apply a constant current (0.125-0.250 mA) for 1-2 h. COMSOL simulations are conducted to determine the field distribution and the potential drop across various tissue layers and equivalent circuit model is developed to calculate the electrophoretic velocity and estimate the drug flux.

RESULTS

The device delivered both hydrophobic and hydrophilic dyes to the tissue. The amount of fluorescein delivered to the vitreous directly correlated with the applied current and time duration. The electrophoretic mobility from the experimental data agreed with the model estimates. Confocal microscopy showed that nile blue penetrated through the conjunctiva-sclera barrier to reach the retina showing that the electric field can transport molecules through the ocular tissue and into the vitreous. The ex vivo model neglects transport into flowing capillaries in the choroid. However, the time scale for electrophoretic transport across the choroid was found to be 550-1300 fold shorter than that for uptake into the choroidal capillaries.

CONCLUSION

Incorporation of an electric field with multiple electrodes on a single lens can effectively deliver ionic drugs to the posterior region at levels comparable to current methods with the benefits of being safer and less invasive.

Natamycin solid lipid nanoparticles - sustained ocular delivery system of higher corneal penetration against deep fungal keratitis: preparation and optimization

Background

Fungal keratitis (FK) is a serious pathogenic condition usually associated with significant ocular morbidity. Natamycin (NAT) is the first-line and only medication approved by the Food and Drug Administration for the treatment of FK. However, NAT suffers from poor corneal penetration, which limits its efficacy for treating deep keratitis.

Purpose

The objective of this work was to prepare NAT solid lipid nanoparticles (NAT-SLNs) to achieve sustained drug release and increased corneal penetration.

Methods

NAT-SLNs were prepared using the emulsification-ultrasonication technique. Box– Behnken experimental design was applied to optimize the effects of independent processing variables (lipid concentration [X₁], surfactant concentration [X₂], and sonication frequency [X₃]) on particle size (R₁), zeta potential (ZP; R₂), and drug entrapment efficiency (EE%) (R₃) as responses. Drug release profile, ex vivo corneal permeation, antifungal susceptibility, and cytotoxicity of the optimized formula were evaluated.

Results

The optimized formula had a mean particle size of 42 r.nm (radius in nanometers), ZP of 26 mV, and EE% reached ~85%. NAT-SLNs showed an extended drug release profile of 10 hours, with enhanced corneal permeation in which the apparent permeability coefficient (P_app) and steady-state flux (J_ss) reached 11.59×10⁻² cm h⁻¹ and 3.94 mol h⁻¹, respectively, in comparison with 7.28×10⁻² cm h⁻¹ and 2.48 mol h⁻¹ for the unformulated drug, respectively. Antifungal activity was significantly improved, as indicated by increases in the inhibition zone of 8 and 6 mm against Aspergillus fumigatus ATCC 1022 and a Candida albicans clinical isolate, respectively, and minimum inhibitory concentration values that were decreased 2.5-times against both of these pathogenic strains. NAT-SLNs were found to be non-irritating to corneal tissue. NAT-SLNs had a prolonged drug release rate^, that improved corneal penetration, and increased antifungal activity without cytotoxic effects on corneal tissues.

Conclusion

Thus, NAT-SLNs represent a promising ocular delivery system for treatment of deep corneal keratitis.

Biofilm Forming Antibiotic Resistant Gram-Positive Pathogens Isolated From Surfaces on the International Space Station

The International Space Station (ISS) is a closed habitat in a uniquely extreme and hostile environment. Due to these special conditions, the human microflora can undergo unusual changes and may represent health risks for the crew. To address this problem, we investigated the antimicrobial activity of AGXX®, a novel surface coating consisting of micro-galvanic elements of silver and ruthenium along with examining the activity of a conventional silver coating. The antimicrobial materials were exposed on the ISS for 6, 12, and 19 months each at a place frequently visited by the crew. Bacteria that survived on the antimicrobial coatings [AGXX® and silver (Ag)] or the uncoated stainless steel carrier (V2A, control material) were recovered, phylogenetically affiliated and characterized in terms of antibiotic resistance (phenotype and genotype), plasmid content, biofilm formation capacity and antibiotic resistance transferability. On all three materials, surviving bacteria were dominated by Gram-positive bacteria and among those by Staphylococcus, Bacillus and Enterococcus spp. The novel antimicrobial surface coating proved to be highly effective. The conventional Ag coating showed only little antimicrobial activity. Microbial diversity increased with increasing exposure time on all three materials. The number of recovered bacteria decreased significantly from V2A to V2A-Ag to AGXX®. After 6 months exposure on the ISS no bacteria were recovered from AGXX®, after 12 months nine and after 19 months three isolates were obtained. Most Gram-positive pathogenic isolates were multidrug resistant (resistant to more than three antibiotics). Sulfamethoxazole, erythromycin and ampicillin resistance were most prevalent. An Enterococcus faecalis strain recovered from V2A steel after 12 months exposure exhibited the highest number of resistances (n = 9). The most prevalent resistance genes were ermC (erythromycin resistance) and tetK (tetracycline resistance). Average transfer frequency of erythromycin, tetracycline and gentamicin resistance from selected ISS isolates was 10⁻⁵ transconjugants/recipient. Most importantly, no serious human pathogens such as methicillin resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococci (VRE) were found on any surface. Thus, the infection risk for the crew is low, especially when antimicrobial surfaces such as AGXX® are applied to surfaces prone to microbial contamination.

Drugging the Small GTPase Pathways in Cancer Treatment: Promises and Challenges

Small GTPases are a family of low molecular weight GTP-hydrolyzing enzymes that cycle between an inactive state when bound to GDP and an active state when associated to GTP. Small GTPases regulate key cellular processes (e.g., cell differentiation, proliferation, and motility) as well as subcellular events (e.g., vesicle trafficking), making them key participants in a great array of pathophysiological processes. Indeed, the dysfunction and deregulation of certain small GTPases, such as the members of the Ras and Arf subfamilies, have been related with the promotion and progression of cancer. Therefore, the development of inhibitors that target dysfunctional small GTPases could represent a potential therapeutic strategy for cancer treatment. This review covers the basic biochemical mechanisms and the diverse functions of small GTPases in cancer. We also discuss the strategies and challenges of inhibiting the activity of these enzymes and delve into new approaches that offer opportunities to target them in cancer therapy.

Drug delivery systems and novel formulations to improve treatment of rare corneal disease

As the field of ocular drug delivery grows so does the potential for novel drug discovery or reformulation in lesser-known diseases of the eye. In particular, rare corneal diseases are an interesting area of research because drug delivery is limited to the outermost tissue of the eye. This review will highlight the opportunities and challenges of drug reformulation and alternative treatment approaches for rare corneal diseases. The barriers to effective drug delivery and proposed solutions in development will be discussed along with an overview of corneal rare disease resources, their current treatments and ophthalmic drug delivery systems that could benefit such cases. The regulatory considerations for effective translation of orphan-designated products will also be discussed.

Ocular adhesives: Design, chemistry, crosslinking mechanisms, and applications

Closure of ocular wounds after an accident or surgery is typically performed by suturing, which is associated with numerous potential complications, including suture breakage, inflammation, secondary neovascularization, erosion to the surface and secondary infection, and astigmatism; for example, more than half of post-corneal transplant infections are due to suture related complications. Tissue adhesives provide promising substitutes for sutures in ophthalmic surgery. Ocular adhesives are not only intended to address the shortcomings of sutures, but also designed to be easy to use, and can potentially minimize post-operative complications. Herein, recent progress in the design, synthesis, and application of ocular adhesives, along with their advantages, limitations, and potential are discussed. This review covers two main classes of ocular adhesives: (1) synthetic adhesives based on cyanoacrylates, polyethylene glycol (PEG), and other synthetic polymers, and (2) adhesives based on naturally derived polymers, such as proteins and polysaccharides. In addition, different technologies to cover and protect ocular wounds such as contact bandage lenses, contact lenses coupled with novel technologies, and decellularized corneas are discussed. Continued advances in this area can help improve both patient satisfaction and clinical outcomes.

Accuracy of the new rapid test for monitoring adalimumab levels

BACKGROUND

The loss of response to adalimumab (ADL) has been related to low serum concentrations at trough. Currently, most methods commercially available for the quantification of ADL are enzyme-linked immunosorbent assay (ELISA) based, with a turnaround time of approximately 8 h, delaying the target dosage adjustment to the subsequent infusion. In this study, we aimed to evaluate the performance of the newly available rapid-test ADL quantification assay by comparing it with three established ELISA methods, using spiked samples and a set of clinical samples.

METHODS

Spiked samples from control donors and 120 serum samples from inflammatory bowel disease (IBD) patients undergoing ADL therapy were quantified using lateral flow Quantum Blue^® Adalimumab and, the ELISA formats from Immundiagnostik, R-Biopharm and an in-house assay.

RESULTS

The rapid-test assay had intraclass correlation coefficients of 0.590, 0.864 and 0.761 when comparing with the Immundiagnostik, R-Biopharm and in-house assays, respectively. For the five therapeutic windows, the accuracy was high: ADL rapid test compared with the Immundiagnostik (58-88%); R-Biopharm, 68-89%; and in house, 60-88%; and kappa statistics revealed 0.492-0.602, 0.531-0.659 and 0.545-0.682, respectively.

CONCLUSIONS

The Quantum Blue^® Adalimumab assay can replace the commonly used ELISA-based ADL quantification kits and it is a reliable alternative to these methods. This rapid-test assay enables the quantitative determination of ADL serum trough level in only 15 min. The developed assay allows measurement of ADL over a wide range. Hence, it represents a valuable tool for the clinician to assess the ADL trough level.

Energy-dependent endocytosis is responsible for drug transcorneal penetration following the instillation of ophthalmic formulations containing indomethacin nanoparticles

Purpose

We previously found that ophthalmic formulations containing nanoparticles prepared by a bead mill method lead to an increase in bioavailability in comparison with traditional formulations (solution type). However, the transcorneal penetration pathway for ophthalmic formulations has not been explained yet. In this study, we investigated the mechanism of transcorneal penetration in the application of ophthalmic formulations containing indomethacin nanoparticles (IMC-NPs).

Materials and methods

IMC-NPs was prepared by the bead mill method. For the analysis of energy-dependent endocytosis, corneal epithelial (HCE-T) cell monolayers and removed rabbit cornea were thermoregulated at 4°C, where energy-dependent endocytosis is inhibited. In addition, for the analysis of different endocytosis pathways using pharmacological inhibitors, inhibitors of caveolae-mediated endocytosis (54 µM nystatin), clathrin-mediated endocytosis (40 µM dynasore), macropinocytosis (2 µM rottlerin) or phagocytosis (10 µM cytochalasin D) were used.

Results

The ophthalmic formulations containing 35–200 nm sized indomethacin nanoparticles were prepared by treatment with a bead mill, and no aggregation or degradation of indomethacin was observed in IMC-NPs. The transcorneal penetration of indomethacin was significantly decreased by the combination of nystatin, dynasore and rottlerin, and the decreased penetration levels were similar to those at 4°C in HCE-T cell monolayers and rabbit cornea. In the in vivo experiments using rabbits, dynasore and rottlerin tended to decrease the transcorneal penetration of indomethacin (area under the drug concentration – time curve in the aqueous humor [AUC_AH]), and the AUC_AH in the nystatin-treated rabbit was significantly lower than that in non-treatment group. In addition, the AUC_AH in rabbit corneas undergoing multi-treatment was obviously lower than that in rabbit corneas treated with each individual endocytosis inhibitor.

Conclusion

We found that three energy-dependent endocytosis pathways (clathrin-dependent endocytosis, caveolae-dependent endocytosis and macropinocytosis) are related to the trans-corneal penetration of indomethacin nanoparticles. In particular, the caveolae-dependent endocytosis is strongly involved.

Impediment of selenite-induced cataract in rats by combinatorial drug laden liposomal preparation

Cataract is the leading cause of blindness globally with surgery being the only form of treatment. But cataract surgery is accompanied by complications, chiefly intra-ocular infections. Hence, preventive nanoformulations may be extremely beneficial. In the present study, novel chitosan-coated liposomal formulations encapsulating a combination of drugs, lanosterol and hesperetin were prepared and characterized. The combinatorial liposomes were prepared by thin film evaporation active extrusion method. The characterization of liposomes was done by transmission electron microscopy, zeta potential, encapsulation efficiency, stability, cytotoxicity and in vitro release studies. The main difference between the chitosan-coated and uncoated combinatorial liposomes is the release of drugs as indicated by the in vitro release studies. The slow and sustained release of the drugs from chitosan-coated ones as against the burst release from uncoated indicates an increased retention time for combinatorial drugs in cornea. This leads to a delay in progression of cataract as seen from in vivo studies. Cytotoxicity studies indicate no cell toxicity of the coating of chitosan or the combination of drugs. Stability studies indicate that there were almost no changes in size, zeta potential and polydispersity index values of the combinatorial liposomes upon storage at room temperature for 60 days. Another important study is the estimation of antioxidant defense system. The estimated values of glutathione reductase, malondialdehyde and chief antioxidant enzymes point toward an upregulation of antioxidant defense system. From the results, it may be concluded that novel chitosan-coated combinatorial liposomes are effective in delaying or preventing of cataract.

In vitro antiplasmodial, antitrypanosomal and antileishmanial activities of selected medicinal plants from Ugandan flora: Refocusing into multi-component potentials

ETHNOPHARMACOLOGICAL RELEVANCE

Seven medicinal plants from Ugandan flora, namely Entada abyssinica, Khaya anthotheca, Vernonia amygdalina, Baccharoides adoensis, Schkuhria pinnata, Entandropragma utile and Momordica foetida, were selected in this study. They are used to treat conditions and infections ranging from inflammations, pains and fevers to viruses, bacteria, protozoans and parasites. Two of the plants, V. amygdalina and M. foetida, are also used as human food or relish, while others are important in ethnoveterinary practices and in zoopharmacognosy in the wild. The aim of this study was to evaluate the in vitro antiplasmodial, antitrypanosomal and antileishmanial activities, along with cytotoxicity of the multi-component extracts of these plants.

MATERIALS AND METHODS

Different parts of the plants were prepared and serially extracted with hexane, petroleum ether, dichloromethane, ethyl acetate, methanol and double distilled water. Solvent free extracts were assayed for in vitro inhibition against four reference parasite strains, Plasmodium falciparum (K1), Trypanosoma brucei rhodesiense (STIB 900), Trypanosoma cruzi (Talahuen C2C4) and Leishmania donovani (MHOM-ET-67/L82) using standard methods. Toxicity was assessed against L6 skeletal fibroblast and mouse peritoneal macrophage (J774) cells and selectivity indices (SIs) calculated for the most active extracts.

RESULTS

The strongest activities, demonstrating median inhibitory concentration (IC₅₀) values ≤ 2 μg/ml, were observed for the dichloromethane and petroleum ether extracts of K. anthotheca, B. adoensis and S. pinnata. Overall, IC₅₀ values ranged from < 1 μg/ml to > 90 μg/ml. Out of 22 extracts demonstrating IC_50s < 20 μg/ml, seven were against T. b. rhodesiense (IC₅₀: 1.6-16.2 μg/ml), six against T. cruzi (IC₅₀: 2.1-18.57 μg/ml), none against L. donovani (IC₅₀: falling > 3.3 and >10 μg/ml), and nine against P. falciparum (IC₅₀: 0.96 μg/ml to 4.69 μg/ml). Selectivity indices (SI) calculated for the most active extracts ranged from <1.00 to 94.24. However, the B. adoensis leaf dichloromethane extract (a) was equipotent (IC₅₀ = 3.3 μg/ml) against L. donovani and L6 cells respectively, indicating non-specific selection. Trypanosome and Plasmodium parasites were comparatively more sensitive to the test extracts.

CONCLUSIONS

The benefits achieved from the seven tested plant species as traditional ethnomedicinal and ethnoveterinary therapies or in zoopharmacognosy against infections and conditions of animals in the wild are strongly supported by results of this study. The synergy of plant extracts, so achieved by concerted actions of the ligands, produces adequate perturbation of targets in the four parasite genera, resulting in the strong potencies exhibited by low IC₅₀ values. The total inhibitory effect, achieved as a sum of perturbations contributed by each participating compound in the extract, minimises toxic effects of the compounds as seen in the high SI's obtained with some extracts. Those extracts demonstrating SI ≥ 4 form promising candidates for further cell-based and system pharmacology studies.

Patients' perspective of the effectiveness and acceptability of pharmacological and non-pharmacological treatments of fibromyalgia

Background and aims Fibromyalgia is a complex condition characterised by widespread pain, sleep disturbance, fatigue and cognitive impairment, with a global mean prevalence estimated at 2.7%. There are inconsistencies in guidelines on the treatment of fibromyalgia leading to dissatisfaction from patients and healthcare professionals. This study investigated patient-reported outcomes of pharmacological and non-pharmacological treatment usage and effectiveness with an assessment of acceptability. Methods Nine hundred and forty-one participants completed a self-administered anonymous questionnaire giving quantitative data of demographics, treatment usage and treatment outcomes. Participant-reported effectiveness and side effects were compared in the following treatment classes: analgesics, antidepressants, gabapentinoids, gastrointestinal treatments, activity interventions, dietary-based treatments, and psychological, physical and alternative therapies. Participants also reported whether they knew about or had tried different treatments. Results The results from the online survey indicated that the range of mean effectiveness ratings were similar for pharmacological and non-pharmacological treatments, whereas non-pharmacological treatments had lower side effects ratings and higher acceptability relative to pharmacological treatments. Participants were not aware of some treatment options. Conclusions The results show lower side effects ratings and higher acceptability for non-pharmacological treatments compared to pharmacological treatments despite similar effectiveness ratings. Implications This article presents results from a large online survey on fibromyalgia patient perspectives of pharmacological and non-pharmacological treatments. Results will inform healthcare professionals and patients about optimal treatments based on ratings of effectiveness, side effects and acceptability that are tailored to patient symptom profiles. Some participants were unaware of treatment options highlighting the importance of patient education allowing collaboration between patients and healthcare professionals to find optimal treatments.

Inhibition of NF-kappaB transcriptional activity enhances fucoxanthinol-induced apoptosis in colorectal cancer cells

Background

Evidence from epidemiological and experimental studies has shown that the etiology of colorectal cancer (CRC) is related to lifestyle, mainly diet. At the same time, there are many foods and beverages that have been shown to provide protection against CRC. We turned our attention to a traditional Japanese food, brown algae, that contains carotenoids and various functional polyphenols, especially fucoxanthin (FX) and fucoxanthinol (FxOH).

Results

Both FX and FxOH treatments induced apoptosis in a dose-dependent and time-dependent manner as detected by annexin V / propidium iodide and the presence of a subG1 population in human colon cancer HCT116 cells. This apoptotic effect of FxOH was stronger than that of FX. We also found that nuclear factor-kappa B (NF-κB) transcriptional activity was significantly increased by treatment with ≥5 μM FxOH. Thus, we cotreated the cells with FxOH plus NF-κB inhibitor, and the results demonstrated that this cotreatment strongly enhanced the induction of apoptosis compared with the effects of FxOH or NF-κB inhibitor treatment alone and resulted in X-linked inhibitor of apoptosis (IAP) downregulation.

Conclusions

This study suggested that FxOH is a more potent apoptosis-inducing agent than FX and that its induction of apoptosis is enhanced by inhibiting NF-κB transcriptional activity via suppression of IAP family genes.

Updates on thermosensitive hydrogel for nasal, ocular and cutaneous delivery

Thermosensitive hydrogels are in situ gelling systems composed of hydrophilic homopolymers or block copolymers which remain as solutions at room temperature and form gels after administration into the body. Its application in advanced drug delivery has gained significant attention in recent years. The tunable characteristics of thermosensitive hydrogels make them versatile and capable of incorporating both hydrophilic and lipophilic compounds and macromolecules. The drug molecules can be included as free molecules or preformulated into nano- or micro-particles or liposomes. Although there were several reviews on the materials of thermosensitive hydrogels, the compatibility between the drug and thermosensitive material as well as its in vitro release mechanisms and in vivo performance have barely been investigated. The current review is proposed aiming to not only provide an update on the recent development in thermosensitive hydrogel formulations for nasal, ocular and cutaneous deliveries, but also identify the relationship between the drug characteristics and the loading strategies, and their impacts on the release mechanisms and the in vivo performance. Our current update for the first time highlights the essential features for successful development of in situ thermosensitive hydrogels to facilitate nasal, ocular or cutaneous drug deliveries.

Recent advances in topical nano drug-delivery systems for the anterior ocular segment

Over the past decade, there has been a rise in the number of clinical cases of moderate to severe anterior segment ocular diseases. Conventional topical ophthalmic formulations have several limitations - to address which, novel drug-delivery systems are needed. Additionally, formidable physiological barriers limit ocular bioavailability through the topical route of application. During the last decade, various nano-scaled ocular drug-delivery strategies have been reported. Some of these exploratory, topical, noninvasive approaches have shown promise in improving penetration into the anterior segment tissues of the eye. In this article, we review the available literature with respect to the safety, efficiency and effectiveness of these nano systems.

Flavonoid Versus Artemisinin Anti-malarial Activity in Artemisia annua Whole-Leaf Extracts

Artemisinin, a sesquiterpene lactone produced by Artemisia annua glandular secretory trichomes, is the active ingredient in the most effective treatment for uncomplicated malaria caused by Plasmodium falciparum parasites. Other metabolites in A. annua or related species, particularly flavonoids, have been proposed to either act as antimalarials on their own or act synergistically with artemisinin to enhance antimalarial activity. We identified a mutation that disrupts the CHALCONE ISOMERASE 1 (CHI1) enzyme that is responsible for the second committed step of flavonoid biosynthesis. Detailed metabolite profiling revealed that chi1-1 lacks all major flavonoids but produces wild-type artemisinin levels, making this mutant a useful tool to test the antiplasmodial effects of flavonoids. We used whole-leaf extracts from chi1-1 and mutant lines impaired in artemisinin production in bioactivity in vitro assays against intraerythrocytic P. falciparum Dd2. We found that chi1-1 extracts did not differ from wild-type extracts in antiplasmodial efficacy nor initial rate of cytocidal action. Furthermore, extracts from the A. annua cyp71av1-1 mutant and RNAi lines impaired in amorpha-4,11-diene synthase gene expression, which are both severely compromised in artemisinin biosynthesis but unaffected in flavonoid metabolism, showed very low or no antiplasmodial activity. These results demonstrate that in vitro bioactivity against P. falciparum of flavonoids is negligible when compared to that of artemisinin.