Development of a sensitive monoclonal antibody-based enzyme-linked immunosorbent assay for the antimalaria active ingredient artemisinin in the Chinese herb Artemisia annua L

High-Performance Liquid Chromatographic Quantification of the Plant Hormone Abscisic Acid at ppb Levels in Plant Samples after a Single Immunoaffinity Column Cleanup

High-performance liquid chromatography with ultraviolet detection (HPLC-UV) is a common analysis technique due to its high versatility and simple operation. In the present study, HPLC-UV detection was integrated with immunoaffinity cleanup (IAC) of the sample extracts. The matrix effect was greatly reduced, and the limit of detection was as low as 1 ng/g of free abscisic acid (ABA) in fresh plant tissues. A monoclonal antibody 3F1 (mAb 3F1) was developed to specifically recognize free ABA but not ABA analogues. The mAb 3F1-immobilized immunoaffinity column exhibited a capacity of 850 ng/mL and an elution efficiency of 88.8-105% for standards. The extraction recoveries of the column for ABA ranged from 80.4 to 108.9%. ABA content was detected in various plant samples with IAC-HPLC-UV. The results were verified with ultraperformance liquid chromatography-electrospray tandem mass spectrometry. IAC-HPLC-UV can be a sensitive and cost-efficient method for plant hormone analysis.

Serological Cross-Reaction between Six Thiadiazine by Indirect ELISA Test and Their Antimicrobial Activity

Malaria is a parasitic infection caused by a protozoon of the genus Plasmodium, transmitted to humans by female biting mosquitoes of the genus Anopheles. Chloroquine and its derivates have caused the parasite to develop drug resistance in endemic areas. For this reason, new anti-malarial drugs as treatments are crucial. This work aimed to evaluate the humoral response. with hyper-immune sera, of mice immunized with six derivatives of tetrahydro-(2H)-1,3,5-thiadiazine-2-thione (bis-THTT) by indirect ELISA test. The cross-reactivity between the compounds as antigens and their microbial activity on Gram-positive and Gram-negative bacteria was evaluated. The results of the humoral evaluation by indirect ELISA show that three bis-THTTs react with almost all of the above. Besides, three compounds used as antigens stimulate the BALB/c mice’s immune system. The best combination of two antigens as a combined therapy displays similar absorbances between the antigens in the mixture, showing similar recognition by antibodies and their compounds. In addition, our results showed that different bis-THTT presented antimicrobial activity on Gram-positive bacteria, mainly on Staphylococcus aureus strains, and no inhibitory activity was observed on the Gram-negative bacteria tested.

Preparation and application of a specific single-chain variable fragment against artemether

Artemether, an artemisinin derivative, is a component of the commonly used artemisinin-based combination therapy, artemether-lumefantrine. In this study, we cloned the VH and VL genes of a cell line (mAb 2G12E1) producing a monoclonal antibody specific to artemether, and used to construct a recombinant DNA of single-chain variable fragment (scFv). The scFv was constructed into prokaryotic expression vectors pET32a (+), pET22b (+), pGEX-2T, and pMAL-p5x, respectively. However, only the pMAL-p5x/scFv could be induced to express soluble scFv with comparable sensitivity and specificity to that of mAb 2G12E1. Based on the anti-artemether scFv, an indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed. The 50% of inhibition concentration (IC₅₀) value and the working range based on IC₂₀ to IC₈₀ were 4.33 ng mL^-1 and 1.05-22.65 ng mL^-1, respectively. The artemether content in different drugs were determined by the developed icELISA, and the results were consistent to those determined by ultra performance liquid chromatography (UPLC). The anti-artemether scFv prepared in the current study could be a valuable genetically engineered antibody applied for artemether monitoring and specific binding mechanism studying.

Determination of artemisinin and its analogs in Artemisia annua extracts by capillary electrophoresis - Mass spectrometry

The applicability of micellar electrokinetic capillary chromatography (MEKC) with mass spectrometric detection for the determination of artemisinin and its analogs (e.g. ascaridole, artemisia ketone, casticin, deoxyartemisinin, arteannuic acid, artemetin, dihydroartemisinic acid) was studied. 40 mM ammonium perfluorooctanoate (pH 9.5) with 2% isopropanol (IPA) was used as background electrolyte (BGE) and the sheath liquid was 50 % (v/v) IPA:water containing 0.1 % formic acid. Separation was performed in a bare fused silica capillary. Artemisinin was detected at 283.1545 m/z as [M+H]⁺ ion. For artemisinin the linear range was found to be 0.6 μg/mL - 60 μg/mL and the limit of detection was 0.18 μg/mL. The RSD% values were 2.6 % for migration times and 4.8 % for peak areas (N = 6). In the ethanolic extracts of Artemisia annua leaves, in addition to artemisinin, a large number of other organic components could be separated and determined. MEKC-MS revealed the existence of diastereomers of several compounds (artemisinin, deoxyartemisinin, dihydroartemisinic acid) in the plant extracts.

Jaceosidin: A Natural Flavone with Versatile Pharmacological and Biological Activities

Nature always remains an inexhaustible source of treasures for mankind. It remains a mystery for every challenge until the completion of the challenge. While we talk about the complicated health issues, nature offers us a great variety of chemical scaffolds and their various moieties packed in the form of natural products e.g., plants, microorganisms (fungi, algae, protozoa), and terrestrial vertebrates and invertebrates. This review article is an update about jaceosidin, a bioactive flavone, from genus Artemisia. This potentially active compound exhibits a variety of pharmacological activities including anti-inflammatory, anti-oxidant, anti-bacterial, antiallergic and anti-cancer activities. The bioactivities and the therapeutic action of jaceosidin, especially the modulation of different cell signaling pathways (ERK1/2, NF-κB, PI3K/Akt and ATM-Chk1/2) which become deregulated in various pathological disorders, have been focused here. The reported data suggest that the bioavailability of this anti-cancer compound should be enhanced by utilizing various chemical, biological and computational techniques. Moreover, it is recommended that researchers and scientists should work on exploring the mode of action of this particular flavone to precede it further as a potent anti-cancer compound.

Salvianolic acid A & B: potential cytotoxic polyphenols in battle against cancer via targeting multiple signaling pathways

Nature has generously offered life-saving therapies to mankind by providing evolutionarily optimized drug-like entities in the form of natural products. These splendid gifts of nature have served as most suitable candidates for anti-cancer drug discovery due to their pleiotropic activity on target molecules. This review aims to provide an update on the natural sources and bioactivities of such gifts from nature, salvianolic acid A & B, which are major bioactive constituents of a traditional Chinses medicinal herb, Salvia miltiorrhiza. Salvianolic acid A & B have been reported to owe anti-cancer, anti-inflammatory and cardioprotective activities. Currently salvianolic acids have been emerged as potent anti-cancer molecules. Salvianolic acid A & B fight cancer progression by prompting apoptosis, halting cell cycle and adjourning metastasis by targeting multiple deregulated signaling networks of cancer. Moreover, salvianolic acid A & B display potency towards sensitizing cancer cells to chemo-drugs. The review purposes that salvianolic acid A & B supply a novel opportunity for drug discovery but further experimentation is mandatory to embellish the knowledge of their pharmacological usage and to access their toxicological limits in order to establish these compounds as potential multitarget future drugs.

Modulation of Autophagy for Controlling Immunity

Autophagy is an essential process that maintains physiological homeostasis by promoting the transfer of cytoplasmic constituents to autophagolysosomes for degradation. In immune cells, the autophagy pathway plays an additional role in facilitating proper immunological functions. Specifically, the autophagy pathway can participate in controlling key steps in innate and adaptive immunity. Accordingly, alterations in autophagy have been linked to inflammatory diseases and defective immune responses against pathogens. In this review, we discuss the various roles of autophagy signaling in coordinating immune responses and how these activities are connected to pathological conditions. We highlight the therapeutic potential of autophagy modulators that can impact immune responses and the mechanisms of action responsible.

Development of monoclonal antibody-based immunoassays for quantification and rapid assessment of dihydroartemisinin contents in antimalarial drugs

Dihydroartemisinin (DHA) is one of the artemisinin derivatives widely used in artemisinin-based combination therapies (ACTs) for malaria treatment. The availability of a point-of-care device for estimation of DHA quantity would allow a quick quality assessment of the DHA-containing drugs. In this study, 9-O-succinylartemisinin was obtained from microbial fermentation of artemisinin, which was hydrogenated to 9-O-succinyldihydroartemisinin as the hapten for DHA. A monoclonal antibody (mAb), designated as 2G₁1G₄, was identified after screening the hybridoma library, which showed 52.3% cross reactivity to artemisinin, but low or no cross reactivity to artesunate, artemether, and several ACTs partner drugs. Based on this mAb, a highly-sensitive, indirect competitive enzyme-linked immunosorbent assay was designed, which showed 50% inhibition concentration of DHA at 1.16 ng/mL, a working range of 0.26-4.87 ng/mL, and limit of detection of 0.18 ng/mL. In addition, a colloidal gold-based lateral flow immunoassay (dipstick) was developed with an indicator range (indicating sensitivity) of 50-100 ng/mL. This dipstick was evaluated for determination of DHA contents in commercial drugs and the results were highly agreeable with those determined by high-performance liquid chromatography.

Fraxinus: A Plant with Versatile Pharmacological and Biological Activities

Fraxinus, a member of the Oleaceae family, commonly known as ash tree is found in northeast Asia, north America, east and western France, China, northern areas of Pakistan, India, and Afghanistan. Chemical constituents of Fraxinus plant include various secoiridoids, phenylethanoids, flavonoids, coumarins, and lignans; therefore, it is considered as a plant with versatile biological and pharmacological activities. Its tremendous range of pharmacotherapeutic properties has been well documented including anticancer, anti-inflammatory, antioxidant, antimicrobial, and neuroprotective. In addition, its bioactive phytochemicals and secondary metabolites can be effectively used in cosmetic industry and as a competent antiaging agent. Fraxinus presents pharmacological effectiveness by targeting the novel targets in several pathological conditions, which provide a spacious therapeutic time window. Our aim is to update the scientific research community with recent endeavors with specifically highlighting the mechanism of action in different diseases. This potentially efficacious pharmacological drug candidate should be used for new drug discovery in future. This review suggests that this plant has extremely important medicinal utilization but further supporting studies and scientific experimentations are mandatory to determine its specific intracellular targets and site of action to completely figure out its pharmacological applications.

Development of a simple and specific direct competitive ELISA for the determination of artesunate using an anti-artesunate polyclonal antiserum

Background

Since artesunate (ART) became a vital component of artemisinin (ARM)-based combination therapies for the treatment for malaria, counterfeit ART drugs have spread in regions of Southeast Asia and Africa. The consumption of counterfeit ART drugs has resulted in the death of many patients. Thus, evaluating the quality of ART drugs is needed. There are several methods for quantitating the ART content in tablets, the most common being a high-performance liquid chromatography. However, that method is hampered by the need for expensive equipment and a rather time-consuming process of extraction. By contrast, enzyme-linked immunosorbent assays (ELISAs) are faster and much less expensive, and they require less sample preparation than the above method. The objective of the present study was to establish a simple and specific direct competitive ELISA for the determination of ART concentrations using an anti-ART polyclonal antibody (pAb).

Results

Anti-ART pAb was raised in mice, and ART-horseradish peroxidase (HRP) conjugate was produced. A direct competitive ELISA was performed by simultaneously incubating ART and the ART-HRP conjugate with the anti-ART pAb over a second antibody. Subsequently, the enzyme activity of the remaining ART-HRP conjugate was measured. The intra- and inter-assay coefficients of variation of the ELISA were less than 10 % in the range of 0.3 to 30 ng/ml with a detection limit of 0.1 ng/ml. The cross-reactivities of the anti-ART pAb with ARM and dihydroartemisinin were 0.12 and 0.04 %, respectively, and those with other antimalarial drugs were negligible. Furthermore, the recovery of 10 or 50 ng/ml ART added to the drug tablet solutions containing an expected amount of 10 ng/ml was estimated by the ELISA. The recovery of the ART amount ranged between 98 and 106 %, with coefficient variations of less than 7.0 %.

Conclusions

The present ELISA is a simple and specific method for the determination of ART concentrations. Thus, this ELISA can be used to identify ART counterfeits and substandard drugs and to quantify the ART drugs.

Development of a Specific Monoclonal Antibody for the Quantification of Artemisinin in Artemisia annua and Rat Serum

Artemisinin, extracted from Artemisia annua, and its derivatives are important frontline antimalarials. To produce specific antibodies for the detection and quantification of artemisinin, artemisinin was transformed to 9-hydroxyartemisinin by microbial fermentation, which was used to prepare a 9-succinate artemisinin hapten for conjugation with ovalbumin. A monoclonal antibody (mAb), designated as 3H7A10, was selected from hybridoma cell lines which showed high specificity to artemisinin. No competitive inhibition was observed with artesunate, dihydroartemisinin, and artemether for up to 20,000 ng mL(-1). An indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed, which showed a concentration causing 50% of inhibition (IC50) for artemisinin as 2.6 ng mL(-1) and a working range of 0.6-11.5 ng mL(-1). The icELISA was applied for the quantification of artemisinin in crude extracts of wild A. annua and the study of pharmacokinetics of artemisinin in rat serum after intraperitoneal injection. The results were highly correlated with those determined by HPLC-UV analysis (R(2) = 0.9919). In comparison with reported antiartemisinin mAbs which have broad cross-reactivity with other artemisinin derivatives, the high specificity of 3H7A10 for artemisinin will enable development of methods for quantification of artemisinin in Artemisia plants and antimalarial drugs such as Arco and for pharmacokinetic studies.

Rapid evaluation of artesunate quality with a specific monoclonal antibody-based lateral flow dipstick

Artesunate is a frontline antimalarial drug for treating Plasmodium falciparum malaria. To produce specific antibodies to artesunate, the carboxyl group of artesunate was directly conjugated to carrier protein as the immunogen. A specific monoclonal antibody (mAb) 3D82G6 against artesunate was obtained by high-throughput screening of positive hybridoma clones. This monoclonal antibody had 4.0, 0.5, and 0.9 % cross reactivities with artemisinin, dihydroartemisinin, and artemether, respectively. A dipstick immunoassay was developed, and the indicator range for artesunate was 1000-2000 ng mL(-1). No interference was observed with artemisinin, dihydroartemisinin, artemether, and other commonly used antimalarial drugs for up to 20,000 ng mL(-1). The dipsticks were used for determination of artesunate contents in commercial drugs, and the results were agreeable with those determined by high-performance liquid chromatography. This dipstick, with its specificity and sensitivity for artesunate and simplicity to use, makes it a potential point-of-care device for rapid quality evaluation of artesunate-containing antimalarial drugs. Graphical Abstract Specific monoclonal antibody-based lateral flow dipstick for artesunate.

Highly specific and sensitive immunoassay for the measurement of prostaglandin E2 in biological fluids

BACKGROUND

Lack of specificity of anti-PGE2 antibodies is a long-standing problem. Given quite a few analogs and low PGE2 content in biological fluids, it is quite important to simultaneously meet the demands of high specificity and sensitivity.

RESULTS

Highly specific anti-PGE2 antibodies were obtained by combined use of cationic carrier protein and Mannich reaction. The cross-reactivity values of the resultant polyclonal and monoclonal antibodies against eight analogs were <14 and <5%, respectively. Furthermore, we established a highly sensitive ELISA, which could be applied to direct analysis of PGE2 at the pg/ml level (LOQ = 15.6 pg/ml).

CONCLUSION

We provide an appropriate strategy to develop a highly-specific and sensitive immunoassay for measuring low PGE2 content in biological samples.

Development of sensitive direct chemiluminescent enzyme immunoassay for the determination of dihydroartemisinin in plasma

Despite significant progress in prevention and therapy, malaria is still one of the world's leading major diseases due to its high morbidity and mortality. Recommended treatments by the World Health Organization include the use of artemisinin and artemisinin derivative-based combination therapies. To allow efficient patient monitoring during antimalarial therapy without the use of expensive apparatus, we developed a sensitive direct chemiluminescent enzyme immunoassay for the determination of dihydroartemisinin in biological fluids. To produce specific antibodies against dihydroartemisinin (DHA), a synthetic DHA derivative was coupled to bovine serum albumin as the immunogen. In parallel, a new, rapid, and efficient procedure to covalently link glycoprotein to all amine-containing molecules has been established and the enzyme tracer was prepared by chemically coupling the DHA derivative in combination with SBP rather than the more commonly used HRP. It allowed us to develop, after optimization of the luminescent reagent, a sensitive and stable luminescent EIA, with a LLOQ of 90 pg mL(-1). This assay compares favorably with the most efficient HPLC methods previously reported with a LLOQ close to 1 ng mL(-1) and shows good precision and efficiency since recovery from human plasma spiked with DHA ranged between 91 and 103%, with coefficients of variation of <13%. To date, no immunoassay for DHA has been applied to plasma analysis and this EIA should be very useful in all clinical laboratories for rapid and cost-effective analysis.

Malaria Diagnosis Across the International Centers of Excellence for Malaria Research: Platforms, Performance, and Standardization

Diagnosis is “the act of identifying a disease, illness, or problem by examining someone or something.” When an individual with acute fever presents for clinical attention, accurate diagnosis leading to specific, prompt treatment often saves lives. As applied to malaria, not only individual patient diagnosis is important but also assessing population-level malaria prevalence using appropriate diagnostic methods is essential for public health purposes. Similarly, identifying (diagnosing) fake antimalarial medications prevents the use of counterfeit drugs that can have disastrous effects. Therefore, accurate diagnosis in broad areas related to malaria is fundamental to improving health-care delivery, informing funding agencies of current malaria situations, and aiding in the prioritization of regional and national control efforts. The International Centers of Excellence for Malaria Research (ICEMR), supported by the U.S. National Institute of Allergy and Infectious Diseases, has collaborated on global efforts to improve malaria diagnostics by working to harmonize and systematize procedures across different regions where endemicity and financial resources vary. In this article, the different diagnostic methods used across each ICEMR are reviewed and challenges are discussed.

Affordable and rapid HPTLC method for the simultaneous analysis of artemisinin and its metabolite artemisinic acid in Artemisia annua L

Artemisinin (AN) and artemisinic acid (AA), valuable phyto-pharmaceutical molecules, are well known anti-malarials, but their activities against diseases like cancer, schistosomiasis, HIV, hepatitis-B and leishmaniasis are also being reported. For the simultaneous estimation of AN and AA in the callus and leaf extracts of A. annua L. plants, we embarked upon a simple, rapid, selective, reliable and fairly economical high performance thin layer chromatography (HPTLC) method. Experimental conditions such as band size, chamber saturation time, migration of solvent front and slit width were critically studied and the optimum conditions were selected. The separations were achieved using toluene-ethyl acetate, 9:1 (v/v) as mobile phase on pre-coated silica gel plates, G 60F254 . Good resolution was achieved with Rf values of 0.35 ± 0.02 and 0.26 ± 0.02 at 536 nm for AN and 626 nm for AA, respectively, in absorption-reflectance mode. The method displayed a linear relationship with r(2) value 0.992 and 0.994 for AN and AA, respectively, in the concentration range of 300-1500 ng for AN and 200-1000 ng for AA. The method was validated for specificity by obtaining in-situ UV overlay spectra and sensitivity by estimating limit of detection (30 ng for AN and 15 ng for AA) and limit of quantitation (80 ng for AN and 45 ng for AA) values. The accuracy was checked by the recovery studies conducted at three different levels with the known concentrations and the average percentage recovery was 101.99% for AN and 103.84% for AA. The precision was analyzed by interday and intraday precision and was 1.09 and 1.00% RSD for AN and 1.22 and 6.05% RSD for AA. The analysis of statistical data substantiates that this HPTLC method can be used for the simultaneous estimation of AN and AA in biological samples.

Artesunate induces apoptosis and inhibits growth of Eca109 and Ec9706 human esophageal cancer cell lines in vitro and in vivo

Esophageal cancer is a common malignant tumor worldwide with a high incidence rate in China and it is a great threat to human health. Combined modality therapy is used for chemotherapeutic treatment of esophageal cancer; however, drug resistance and side effects of the drugs is a major barrier to the success of chemotherapy. As chemotherapy with common drugs is far from providing satisfactory clinical outcomes for patients with esophageal cancer, more efficient drugs are urgently required. Artesunate (Art) is the first-line treatment option for malaria; however, it was recently revealed that Art has remarkable anti-tumor activity, making it a novel candidate for cancer chemotherapy. Although the anti-cancer effects of Art have been well documented, its potential against esophageal cancer has rarely been explored. The present study aimed to investigate the significance and mechanism of the anti-proliferative activity of Art on esophageal cancer cells in vitro and in vivo. In the in vitro experiments, Art inhibited the growth as well as induced cell apoptosis and cell cycle arrest of esophageal cancer cell lines (Eca109 and Ec9706) in a concentration-dependent manner. Furthermore, downregulation of mitochondrial membrane potential, B-cell lymphoma-2 (BCL-2) and CDC25A, as well as upregulation of BCL-2‑associated X protein (Bax) and caspase-3 expression in Art-treated cells were identified. In addition, an in vivo study showed that Art produced a dose-dependent tumor regression in nude mice, while side effects were low. The anti-tumor activity of 200 mg/kg Art was similar to that of 3 mg/kg cisplatin. In conclusion, Art exerted concentration-dependent inhibitory activity against esophageal cancer in vivo and in vitro by inducing cell apoptosis and cell cycle arrest through affecting mitochondrial membrane potential, BCL-2, Bax, caspase-3 and CDC25A.

Monoclonal antibody-based immunoassay for analysis of octopamine in housefly

Octopamine (OA) is one of the biogenic monoamines in the housefly, which acts as an important neurohormone in the physiological process of this pest. In this study, a new hapten of OA was synthesized via aldol condensation. With the hapten, monoclonal antibodies (MAb) were generated and their characterizations were investigated. An indirect competitive enzyme-linked immunosorbent assay (icELISA) based on MAb 3C11-E3 was established, which required simple sample pre-treatments and had low cross-reactivity with OA structural analogise. The half maximal inhibition concentration (IC50) and the detected range (IC20-IC80) of the icELISA were 128 ng/mL and 12-1438 ng/mL, respectively. Average recoveries of OA ranged from 73 to 129% in the housefly.

Development of a colloidal gold-based lateral flow dipstick immunoassay for rapid qualitative and semi-quantitative analysis of artesunate and dihydroartemisinin

Background

Artemisinin-based combination therapy (ACT) plays an indispensable role in malaria control and elimination. However, the circulation of counterfeit, substandard drugs has greatly threatened malaria elimination campaigns. Most methods for the analysis of artemisinin and its derivatives require expensive equipment and sophisticated instrumentation. A convenient, easy-to-use diagnostic device for rapid evaluation of the quality of artemisinin drugs at the point-of-care is still lacking. In this study a lateral flow dipstick immunoassay was developed for qualitative and semi-quantitative analysis of artesunate (ATS) and dihydroartemisinin (DHA) in anti-malarial drugs.

Methods

This assay was based on a monoclonal antibody (mAb) raised against ATS. ATS-bovine serum albumin and goat anti-mouse IgG, used as the test capture reagent and the control capture reagent, were coated on the nitrocellulose membrane to form the test line and control line, respectively. The conjugate pad was saturated with the gold-labelled anti-ATS mAb.

Results

The indicator range of the dipsticks, defined as lowest concentration of the target analytes between which the test line was not visible, were 100-200 and 200-500 ng mL^-1 for ATS and DHA, respectively. No competitive inhibition was observed up to 5,000 ng mL^-1 of quinine, chloroquine diphosphate salt, primaquine phosphate, pyrimethamine, lumefantrine, amodiaquine, piperaquine tetraphosphate tetrahydrate or pyronaridine tetraphosphate. Semi-quantitative analysis of ATS and DHA in commercial drugs and raw drug materials with the dipsticks produced result agreeable with those determined by high performance liquid chromatography (HPLC). Storage test showed that the indicator range for artemisinins remained unchanged after a week at 37°C and increased four-folds after six months of storage at 4°C or ambient temperature.

Conclusions

The new selected mAb 3D₈2G₇ with high avidity and broad cross reactivity for artemisinins was used to develop and optimize a dipstick immunoassay for qualitative and semi-quantitative analysis of ATS and DHA in anti-malarial drugs. The semi-quantitative analysis of ATS and DHA in commercial drugs and raw drug materials, and the specificity test of the artemisinin-related drugs both proved the accurate performance of the developed dipsticks for semi-quantitation of ACT samples. The dipstick may be used as a point-of-care device for identifying substandard and counterfeit ATS- and DHA-containing anti-malarial drugs.

Holotransferrin enhances selective anticancer activity of artemisinin against human hepatocellular carcinoma cells

Artemisinin, also termed qinghaosu, is extracted from the traditional Chinese medicine artemesia annua L. (the blue-green herb) in the early 1970s, which has been confirmed for effectively treating malaria. Additionally, emerging data prove that artemisinin exhibits anti-cancer effects against many types of cancers such as leukemia, melanoma, etc. Artemisinin becomes cytotoxic in the presence of ferrous iron. Since iron influx is high in cancer cells, artemisinin and its analogs selectively kill cancer cells with increased intracellular iron concentrations. This study is aimed to investigate the selective inhibitory effects of artemisinin on SMMC-7721 cells in vitro and determine the effect of holotransferrin, which increases the concentration of ferrous iron in cancer cells, combined with artemisinin on the anticancer activity. MTT assay was used for assessing the proliferation of SMMC-7721 cells treated with artemisinin. The induction of apoptosis and inhibition of colony formation in SMMC-7721 cells treated with artemisinin were determined by TdT-mediated dUTP nick end labeling (TUNEL) and colony formation assay, respectively. The results showed that artemisinin at various concentrations significantly inhibited growth, colony formation and cell viability of SMMC-7721 cells (P<0.05), likely due to induction of apoptosis of SMMC-7721 cells. Of interest, it was found that incubation of artemisinin combined with holotransferrin sensitized the growth inhibitory effect of artemisinin on SMMC-7721 cells (P<0.01). Our data suggest that treatment with artemisinin leads to inhibition of viability and proliferation, and apoptosis of SMMC-7721 cells. Furthermore, we observed that holotransferrin significantly enhanced the anti-cancer activity of artemisinin. This study may provide a potential therapeutic choice for liver cancer.

Development of a specific monoclonal antibody-based ELISA to measure the artemether content of antimalarial drugs

Artemether is one of the artemisinin derivatives that are active ingredients in antimalarial drugs. Counterfeit and substandard antimalarial drugs have become a serious problem, which demands reliable analytical tools and implementation of strict regulation of drug quality. Structural similarity among artemisinin analogs is a challenge to develop immunoassays that are specific to artemisinin derivatives. To produce specific antibodies to artemether, we used microbial fermentation of artemether to obtain 9-hydroxyartemether, which was subsequently used to prepare a 9-O-succinylartemether hapten for conjugation with ovalbumin as the immunogen. A monoclonal antibody (mAb), designated as 2G12E1, was produced with high specificity to artemether. 2G12E1 showed low cross reactivities to dihydroartemisinin, artemisinin, artesunate and other major antimalarial drugs. An indirect competitive enzyme linked immunosorbent assay (icELISA) developed showed a concentration causing 50% of inhibition for artemether as 3.7 ng mL⁻¹ and a working range of 0.7-19 ng mL⁻¹. The icELISA was applied for determination of artemether content in different commercial drugs and the results were comparable to those determined by high-performance liquid chromatography analysis. In comparison with reported broad cross activity of anti-artemisinin mAbs, the most notable advantage of the 2G12E1-based ELISA is its high specificity to artemether only.

Validation of ELISA for quantitation of artemisinin-based antimalarial drugs

The circulation of counterfeit or substandard artemisinins (ARTs) in malaria-endemic areas poses a serious threat to the long-term use of these drugs. Here, we validated an indirect competitive enzyme-linked immunosorbent assay (icELISA) for quantification of ARTs and found that 50% of inhibitory concentrations of dihydroartemisinin, artemether, and artesunate were 8.1, 207.0, and 4.7 ng/mL, respectively. We compared the icELISA with high-performance liquid chromatography (HPLC) for quantifying ART and its derivatives in 22 convenience samples of commercial antimalarial drugs. Paired t tests showed a borderline significant difference between the two methods (mean = 0.03, 95% confidence interval [CI] 0.00-0.07, P = 0.074) and the icELISA results were more variable than those of the HPLC analysis (P < 0.001), suggesting that further improvement is needed to enhance the performance of the icELISA. Our results showed that the icELISA has the potential to be improved for quality assurance of ARTs at the point of care in endemic settings.

A rapid method for the determination of artemisinin and its biosynthetic precursors in Artemisia annua L. crude extracts

A rapid high-pressure liquid chromatography (HPLC) tandem mass spectrometry (TQD) method for the determination of artemisinin, 9-epi-artemisinin, artemisitene, dihydroartemisinic acid, artemisinic acid and arteannuin B in Artemisia annua extracts is described. Detection and quantification of 9-epi-artemisinin in crude extracts are reported for the first time. In this method all six metabolites are resolved and eluted within 6 min with minimal sample preparation. A recovery of between 96.25% and 103.59% was obtained for all metabolites analysed and the standard curves were linear (r(2)>0.99) over the concentration range of 0.15-10 μg mL(-1) for artemisinin, 9-epi-artemisinin, artemisitene and arteannuin B, and the range of 3.75-120 μg mL(-1) for dihydroartemisinic acid and artemisinic acid. All validation indices were satisfactory, showing the method to be robust, quick, sensitive and adequate for a range of applications including high throughput (HTP) analysis.

LC-UV/MS quality analytics of paediatric artemether formulations

A highly selective and stability-indicating HPLC-method, combined with appropriate sample preparation steps, is developed for β-artemether assay and profiling of related impurities, including possible degradants, in a complex powder for oral suspension. Following HPLC conditions allowed the required selectivity: a Prevail organic acid (OA) column (250 mm×4.6 mm, 5 μm), flow rate set at 1.5 mL/min combined with a linear gradient (where A=25 mM phosphate buffer (pH 2.5), and B=acetonitrile) from 30% to 75% B in a runtime of 60 min. Quantitative UV-detection was performed at 210 nm. Acetonitrile was applied as extraction solvent for sample preparation. Using acetonitrile-water mixtures as extraction solvent, a compartmental behaviour by a non-solving excipient-bound fraction and an artemether-solubilising free fraction of solvent was demonstrated, making a mobile phase based extraction not a good choice. Method validation showed that the developed HPLC-method is considered to be suitable for its intended regulatory stability-quality characterisation of β-artemether paediatric formulations. Furthermore, LC-MS on references as well as on stability samples was performed allowing identity confirmation of the β-artemether related impurities. MS-fragmentation scheme of β-artemether and its related substances is proposed, explaining the m/z values of the in-source fragments obtained.

Preparation of a single-chain variable fragment and a recombinant antigen-binding fragment against the anti-malarial drugs, artemisinin and artesunate, and their application in an ELISA

Two different recombinant antibodies, a single-chain variable fragment (scFv) and an antigen-binding fragment (Fab), were prepared against artemisinin (AM) and artesunate (AS) and were developed for use in an enzyme-linked immunosorbent assay (ELISA). The recombinant antibodies, which were derived from a single monoclonal antibody against AM and AS (mAb 1C1) prepared by us, were expressed by Escherichia coli cells and their reactivity and specificity were characterized. As a result, to obtain sufficient signal in indirect ELISA, a much greater amount of a first antibody was needed in the use of scFv due to the differences of the secondary antibody and conformational stability. Therefore, we focused on the development of the recombinant Fab antibodies and applied it to indirect competitive ELISA. The specificity of the Fab was similar to that of mAb 1C1 in that it showed specific reactivity toward AM and AS only. The sensitivity of the icELISA (0.16 μg/mL to 40 μg/mL for AM and 8.0 ng/mL to 60 ng/mL for AS) was sufficient for analysis of antimalarial drugs, and its utility for quality control of analysis of Artemisia spp. was validated. The Fab expression and refolding systems provided a good yield of high-quality antibodies. The recombinant antibody against AM and AS provides an essential component of an economically attractive immunoassay and will be useful in other immunochemical applications for the analysis and purification of antimalarial drugs.

Antimalarial Effects of Iranian Flora Artemisia sieberi on Plasmodium berghei In Vivo in Mice and Phytochemistry Analysis of Its Herbal Extracts

The aim of this study is pharmacochemistry of Iranian flora Artemisia sieberi and its antimalarial effects on Plasmodium berghei in vivo. This is the first application of A. sieberi for treatment of murine malaria. A. sieberi were collected at flowering stage from the Khorassan and Semnan provinces of Iran; the aerial parts were air-dried at room temperature and then powdered. The powder was macerated in methanol, filtered with Bokhner hopper and solvent was separated in rotary evaporator. Total herbal extract was subsequently processed for ether and chloroform extracts preparation. The toxicity of herbal extract was assessed on naive NMRI mice with high, average and low doses; then pathophysiological signs were assessed. Finally, the antimalarial efficacy was investigated on two groups of Plasmodium berghei infected mice. Percentage of parasitaemia and pathophysiology were also evaluated. The results of this assessment showed no toxicity even by high concentration of herbal extract. A significant reduction in percentage of parasitaemia was observed; no alterations of hepatosplenomegaly and body weight were indicated in study group. A. sieberi extracts showed antimalarial effects against murine malaria with some efficacies on reducing pathophysiology. However, there is requirement to find the major component of this herbal extract by further studies.

A combination of ultrasonic-assisted extraction with RRLC-QQQ method for the determination of artemisinin in the Chinese herb Artemisia annua L

INTRODUCTION

Artemisinin, the primary active ingredient of the Chinese herb Artemisia annua L., is known to have considerable anti-malaria properties. However, rapid, sensitive and selective method for the determination of artemisinin in it is not currently available.

OBJECTIVE

To develop and validate an efficient method for extraction and analysis of artemisinin from the plant samples of Artemisia annua L. by rapid resolution liquid chromatography triple quadrupole mass spectrometry (RRLC-QQQ).

METHODOLOGY

Following ultrasound-assisted extraction (USE), RRLC-QQQ was utilised to separate and determine artemisinin from the plant sample of Artemisia annua L. The LC separation, QQQ-MS detection and multiple reaction monitoring (MRM) mode were optimised, and the method validation concluding selectivity, calibration, accuracy and precision, and recovery were also evaluated.

RESULTS

LC separation was performed with an isocratic elution of 20% of methanol-water (10 mmol/L ammonium acetate, pH 4.0) on a C(18) column. The triple quadrupole MS detection was carried out under MRM mode of precursor ion [M + H]+ → fragment ions m/z 265.1 and m/z 247.2. The limits of detection and quantitation of artemisinin were 0.20 and 0.75 ng/mL, respectively. The intra- and inter-day precisions did not exceed 3.71%, and the deviation of the intra- and inter-day mean values did not exceed ±7.50. The average recoveries for artemisinin ranged from 92.45 to 103.8% with an RSD from 2.47 to 2.79%.

CONCLUSION

The developed RRLC-QQQ assay is an efficient method for separation and determination of artemisinin from the plant samples of Artemisia annua L.

The genus Artemisia: a comprehensive review

CONTEXT

Medicinal plants are nature's gift to human beings to make disease free healthy life, and play a vital role to preserve our health. They are believed to be much safer and proven elixir in the treatment of various ailments. The genus Artemisia (Astraceae) consists of about 500 species, occurring throughout the world. The present review comprises the ethnopharmacological, phytochemical and therapeutic potential of various species of Artemisia.

OBJECTIVE

The aim of this this review is to bring together most of the available scientific research conducted on the genus Artemisia, which is currently scattered across various publications. Through this review the authors hope to attract the attention of natural product researchers throughout the world to focus on the unexplored potential of Artemisia species.

METHODS

This review has been compiled using references from major databases such as Chemical Abstracts, Medicinal and Aromatic Plants Abstracts, ScienceDirect, SciFinder, PubMed, King's American Dispensatory, Henriette's Herbal Homepage, Dr. Duke's Phytochemical and Ethnobotanical Databases.

RESULTS

An exhaustive survey of literature revealed that the different species of Artemisia have a vast range of biological activities including antimalarial, cytotoxic, antihepatotoxic, antibacterial, antifungal and antioxidant activity. Some very important drug leads have been discovered from this genus, notably artemisinin, the well known antimalarial drug isolated from the Chinese herb Artemisia annua. Terpenoids, flavonoids, coumarins, caffeoylquinic acids, sterols and acetylenes constitute major classes of phytoconstituents of the genus.

CONCLUSION

Various species of Artemisia seems to hold great potential for in-depth investigation for various biological activities, especially their effects on the central nervous and cardiovascular systems.

Artemisinin directly targets malarial mitochondria through its specific mitochondrial activation

The biological mode of action of artemisinin, a potent antimalarial, has long been controversial. Previously we established a yeast model addressing its mechanism of action and found mitochondria the key in executing artemisinin's action. Here we present data showing that artemisinin directly acts on mitochondria and it inhibits malaria in a similar way as yeast. Specifically, artemisinin and its homologues exhibit correlated activities against malaria and yeast, with the peroxide bridge playing a key role for their inhibitory action in both organisms. In addition, we showed that artemisinins are distributed to malarial mitochondria and directly impair their functions when isolated mitochondria were tested. In efforts to explore how the action specificity of artemisinin is achieved, we found strikingly rapid and dramatic reactive oxygen species (ROS) production is induced with artemisinin in isolated yeast and malarial but not mammalian mitochondria, and ROS scavengers can ameliorate the effects of artemisinin. Deoxyartemisinin, which lacks an endoperoxide bridge, has no effect on membrane potential or ROS production in malarial mitochondria. OZ209, a distantly related antimalarial endoperoxide, also causes ROS production and depolarization in isolated malarial mitochondria. Finally, interference of mitochondrial electron transport chain (ETC) can alter the sensitivity of the parasite towards artemisinin. Addition of iron chelator desferrioxamine drastically reduces ETC activity as well as mitigates artemisinin-induced ROS production. Taken together, our results indicate that mitochondrion is an important direct target, if not the sole one, in the antimalarial action of artemisinins. We suggest that fundamental differences among mitochondria from different species delineate the action specificity of this class of drugs, and differing from many other drugs, the action specificity of artemisinins originates from their activation mechanism.