Direct determination of opium alkaloid-bovine serum albumin conjugate by matrix-assisted laser desorption/ionization mass spectrometry

Matrix-Free Laser Desorption Ionization Mass Spectrometry as an Efficient Tool for the Rapid Detection of Opiates in Crude Extracts of Papaver somniferum

Having a long history of traditional medicinal applications, Papaver somniferum is also known as a source of various pharmacologically highly active opiates. Consequently, their detection from plant extracts is an important analytical task and generally addressed by methods of GC-MS and LC-MS. However, opiates do also show structural similarities to matrix molecules used in matrix-assisted laser desorption ionization (LDI) and may therefore ionize upon simple laser irradiation. Following this analytical approach, the present work thoroughly evaluated the direct detection of opiates by matrix-free LDI in crude extracts of P. somniferum. The method facilitated the identification of 10 reported opiates by their molecular formulas without any chromatographic prepurification. Moreover, a principal component analysis based on LDI-MS data permitted the correct grouping of all extracts according to their inherent chemistry. Concluding experiments on serial dilutions of thebaine further evaluated potential quantitative applications of the method. Overall results highlight the promising potential of LDI-MS for the swift detection of opiates in complex mixtures.

An immunochromatographic assay for rapid etection of salvinorin A

We developed an immunochromatographic assay (ICA) that enables rapid analysis of salvinorin A (Sal A) in Salvia divinorum within 10 min. The result shows that no Sal A in other samples of Lamiaceae plants was detected, but it could recognize Sal A among other substances in complex samples. The main advantage of the ICA is its high performance in combination with low cost, simplicity, and speed. Our newly developed combined ICA/indirect competitive ELISA(icELISA) system enables analysis of large numbers of samples over short periods of time without cumbersome pretreatments in complex mixtures. This method can complement other instrumental analyses for salvinorins, and could be used to deter S. divinorum abuse.

Development of an immunoassay using an anti-wogonin glucuronide monoclonal antibody

Wogonin 7-O-β-D-glucuronide (Wgn) is a bioactive flavone present in the dried root of Scutellaria baicalensis Georgi. To generate a monoclonal antibody (MAb) against Wgn, BALB/c mice injected with Wgn-bovine serum albumin yielded splenocytes that we fused with SP2/0 myeloma cells using the polyethylene glycol method. We obtained a hybridoma designated 315A that produced a MAb reactive to Wgn. The anti-Wgn MAb 315A was applied to an indirect competitive enzyme-linked immunosorbent assay (icELISA) to quantify Wgn. Subsequent validation revealed that icELISA using the 315A anti-Wgn MAb is an accurate and reliable method for the quantification of Wgn in S. baicalensis.

Generation of an anti-Dabigatran Monoclonal Antibody and Its Use in a Highly Sensitive and Specific Enzyme-Linked Immunosorbent Assay for Serum Dabigatran

BACKGROUND

Dabigatran (DT) is a direct thrombin inhibitor used to prevent venous and arterial thromboembolism due to atrial fibrillation. DT is the active form of the commercially available prodrug DT etexilate. Although DT has many clinical advantages over warfarin, it increases the incidence of bleeding in patients with renal dysfunction. Circulating levels of DT are increased in such patients because it is mainly eliminated by renal excretion. Therapeutic drug monitoring may therefore help to prevent adverse DT effects, but no method for measuring circulating DT levels has been reported, except for an analysis by liquid chromatography-tandem mass spectrometry. This study sought to develop a novel enzyme-linked immunosorbent assay (ELISA) to measure DT concentrations.

METHODS

Mice were immunized with a DT-keyhole limpet hemocyanin conjugate to generate an anti-DT antibody. Immunized mouse splenocytes and myeloma cells (SP2/0) were fused to obtain an anti-DT monoclonal antibody (DT-mAb). DT-mAb and DT solutions were added to microplate wells coated with a DT-human serum albumin conjugate. DT concentrations were determined based on the principles of ELISA.

RESULTS

DT-mAb was successfully purified from a hybridoma, and the competitive ELISA developed using this DT-mAb could evaluate DT concentrations ranging from 7.8 to 125 ng/mL. The ELISA signal was not linear using DT-spiked serum; however, it was linear when serum ultrafiltrate was used. Weak cross-reactivity with DT etexilate was detected, but no cross-reactivity was observed with other structurally related drugs or drugs commonly used for the treatment of atrial fibrillation.

CONCLUSIONS

The developed competitive ELISA is a valuable and specific tool to analyze free DT in serum ultrafiltrate for therapeutic drug monitoring and pharmacokinetic studies.

Development of an enzyme immunoassay using a monoclonal antibody against the psychoactive diterpenoid salvinorin A

Salvinorin A (1), the main active constituent in Salvia divinorum, is a highly selective kappa-opioid receptor agonist with hallucinogenic effects, which is regulated in several countries. In the present study, a monoclonal antibody (mAb) against 1 was prepared, and an indirect competitive enzyme-linked immunosorbent assay (icELISA) system was developed for the detection of salvinorins. To raise mAbs against 1, salvinorin B (2) hemisuccinate was synthesized and used to prepare the immunogen 2-bovine serum albumin conjugate. This technique was used to prepare a hybridoma cell line, 3D5, which secreted a mAb that recognized 1. The mAb was shown to have specificity for 1 and other salvinorins in cross-reactivity tests. The intra-assay calibration range by icELISA using the mAb against 1 was 0.0195-0.625 μg/mL. After validating the icELISA using intra- and interassays, a recovery experiment and analysis of several plants in the family Lamiaceae, including S. divinorum, confirmed that the analytical method based on ELISA is not only simple but also precise, accurate, sensitive, and sufficiently reliable. The results indicate that icELISA is a useful tool in the identification of S. divinorum.

Standardization of Licorice and TCM Formulations Using Eastern Blot Fingerprinting Analysis

To prepare the antiglycyrrhizin (GC) monoclonal antibody (MAb), GC was treated with NaIO4resulting in aldehyde which can be combined with carrier protein. An antigen conjugate was performed by a matrix-assisted laser desorption/ionization TOF mass spectrometry to determine the hapten numbers in the conjugate. Anti-GC MAb was prepared from a hybridoma which was fixed from the spleen cells producing anti-GC MAb and the myeloma cells after immunization. The TCM and licorice extract were developed by TLC and blotted to a polyvinylidene difluoride (PVDF) membrane. The membrane was treated by NaIO4and protein, enzyme labeled secondary MAb, and finally substrate was added. Clear spot appeared on PVDF membrane identifying GC against a background containing large amount of impurities. In eastern blotting, the GC molecule was divided into two functions. The aglycone part is recognized as an epitope and the sugar moiety can be combined to membrane. The specific reactivity of sugar moiety in the GC molecule against anti-GC MAb might be modified by the NaIO4treatment on the membrane because glycyrrhetic acid 3-O-glucuronide can be stained although the cross-reactivity is only 4.3%. Eastern blotting for GC can not only apply for the standardization of licorice and TCM, but also it can open for the other bioactive products.

Production of monoclonal antibodies and ELISA for thebaine and codeine

The ratio of hapten and bovine serum albumin in antigen conjugate was exactly determined by matrix-assisted laser desorption/ionization mass spectrometry. Monoclonal antibodies against thebaine and codeine were produced by hybridoma fused with the sprenocytes immunized with thebaine- and codeine-bovine serum albumin conjugate and HAT-sensitive mouse myeloma cell line, P3-X63-Ag8-653. No cross-reaction of anti-thebaine antibody against morphine was observed. Very small cross-reaction appeared in codeine (0.004%). The cross-reaction of anti-codeine antibody against morphine and thebaine was 2.97 and 5.98%, respectively. The full measuring range of the assay extends from 60 pg mL to 1 ng mL for thebaine and 1 ng mL to 100 ng mL for codeine.

Production of monoclonal antibodies and development of an ELISA for solamargine

The ratio of hapten and bovine serum albumin in an antigen conjugate was determined by matrix-assisted laser desorption/ionization mass spectrometry. A hybridoma secreting monoclonal antibodies against solamargine was produced by fusing splenocytes immunized with a solamargine-bovine serum albumin conjugate with HAT-sensitive mouse myeloma cell line, P3-X63-Ag8-653. Extensive cross-reaction of anti-solamargine antibodies against solasonine appeared. Aglycone of solamargine, solasodine cross-reacted with anti-solamargine antibodies resulting in a 43.8% cross-reaction. Insignificant cross-reaction appeared with tomatine (2.06%). The full measuring range of the assay extends from 57.5 pmol ml(-1) to 11.5 nmol ml(-1) of solamargine.

Application of Monoclonal Antibodies against Bioactive Natural Products: Eastern Blotting and Preparation of Knockout Extract

Matrix-assisted laser desorption/ionization (MALDI) tof mass spectrometry was used for the confirmation of hapten number in synthesized antigen. As application of MAb, the MAbs against ginsenosides and glycyrrhizin have been prepared resulting in the development of two new techniques that we named the eastern blotting method and the knockout extract preparation. In eastern blotting technique, glycosides like ginsenosides and glycyrrhizin separated by silica gel TLC were blotted to PVDF membrane that was treated with a NaIO₄ solution followed by BSA resulted in glycoside-BSA conjugate on a PVDF membrane. The blotted spots were stained by MAb. Double staining of eastern blotting for ginsenosides using antiginsenoside Rb₁ and Rg₁ MAbs promoted complete identification of ginsenosides in Panax species. The immunoaffinity concentration of glycyrrhizin was determined by immunoaffinity column conjugated with antiglycyrrhizin MAb resulting in the glycyrrhizin-knockout extract, which was determined by the synergic effect with glycyrrhizin on NO production using the cell line.

Preparation of monoclonal antibody against crocin and its characterization

Three crocin-carrier protein conjugates were synthesized and their hapten numbers were determined by matrix-assisted laser desorption/ionization time of flight mass spectrometry. Three monoclonal antibodies against crocin were produced by hybridomas fused with the splenocytes immunized with crocin hemisuccinate-bovine serum albumin conjugate and HAT-sensitive mouse myeloma cell line, P3-X63-Ag8-653. They were identified as IgG2a and IgG2b possessing lambda light chain, respectively. Their wide reactivities against crocetin glycosides were discussed.

Monoclonal Antibodies against Small Molecule Natural Products and Their Applications, Eastern Blotting and Knockout Extract

To determine the hapten number in hapten-carrier protein conjugate matrix-assisted laser desorption/ionization (MALDI) tof mass spectrometry was applied. Highly specific anti-ginsenoside Rb₁ and Rg₁ monoclonal antibodies (MAbs) were prepared. Ginsenosides were developed on thin layer chromatography (TLC) plates which were covered by a polyvinylidene difluoride (PVDF) membrane resulting in blotting. The membrane was treated with NaIO₄ solution to release the aldehyde group on the sugar moiety of the ginsenosides. By treatment of the membrane with a protein solution the ginsenoside-protein conjugation as a Schiff-base occurred, which can function to fix it to the PVDF membrane. A part of the ginsenoside aglycone was reacted with anti-ginsenoside Rb₁ MAb, secondary MAb conjugated with enzyme and finally a substrate was added, resulting in a specific and highly sensitive staining that we named Eastern blotting. Furthermore, it makes one-step isolation of ginsenoside Rb₁ possible using an immuno-affinity column conjugated with anti-ginsenoside Rb₁ MAb. Furthermore, immunoaffinity concentration was carried out allowing high sensitivity analysis of lower concentrations of ginsenoside Rb₁ so that several unknown bands could be structurally determined.

Solution- and Crystal-Phase Covalent Modification of Lysozyme by a Purpose-Designed Organoruthenium Complex. A MALDI-TOF MS Study of its Metal Binding Sites

Study of the reaction between the transition organometallic complex 4-ruthenocenyl 2,6-dimethylpyrylium tetrafluoroborate and the enzyme hen egg white lysozyme (HEWL) in solution and by diffusion in crystals was performed by use of a combination of spectroscopic and chromatographic methods. Conjugation involving the lysine residues of lysozyme appeared to occur readily, yielding very stable ruthenocenyl pyridinium adducts with average degrees of incorporation ranging from 0.2 to 1.8 metal complexes per protein molecule, depending on reaction conditions. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) revealed that the protein conjugates were in fact mixtures of unmodified, mono-, di- and sometimes tripyridinium adducts. In combination with reversed-phased HPLC, we were able to show that six different monoruthenocenyl pyridinium adducts were formed in solution. This result was confirmed by trypsin digestion of a ruthenocenyl pyridinium conjugate and MALDI-TOF MS analysis of the peptide mixture, which showed that lysines 1, 13, 33, 96, 97 and 116 were involved in the reaction with the pyrylium complex, lysines 13, 33 and 116 being the major binding sites. In the tetragonal crystal state, no binding of the ruthenium complex was shown to occur at lysine 116, owing to steric hindrance at this particular position.

Enzyme-linked immunosorbent assay for glycyrrhizin using anti-glycyrrhizin monoclonal antibody and an eastern blotting technique for glucuronides of glycyrrhetic acid

Hybridomas secreting a monoclonal antibody against glycyrrhizin were produced by fusing splenocytes from a mouse immunized against a glycyrrhizin-bovine serum albumin conjugate with the hypoxanthine-aminopterin-thymidine-sensitive mouse myeloma cell line, P3-X63-Ag8-653. A very weak cross-reaction with glycyrrhetinic acid monoglucuronide and glycyrrhetic acid occurred. An enzyme-linked immunosorbent assay (ELISA) that had an effective measuring range of 20 -200 ng/mL of glycyrrhizin was established using this monoclonal antibody. In addition, a method named eastern blotting for the detection of glycyrrhizin was investigated. In this method, we developed a new way to separate the glycyrrhizin molecule into two functional parts using a simple and well-known chemical reaction. The sugar parts were oxidized by sodium periodate to give dialdehydes, which reacted with amino groups on the protein and covalently bound to the adsorbent membrane. The monoclonal antibody bound to the aglycone part of the glycyrrhizin molecule for immunostaining. This method was validated by immunocytolocalization of glycyrrhizin in fresh Glycyrrhiza root.

Formation of monoclonal antibody against a major ginseng component, ginsenoside Rg1 and its characterization. Monoclonal antibody for a ginseng saponin

The ratio of hapten and bovine serum albumin in an antigenconjugate was determined by matrix-assisted laserdesorption/ionization time-of-flight mass spectrometry. Ahybridoma secreting monoclonal antibody against ginsenosideRg(1) was produced by fusing sprenocytes immunized with aginsenoside Rg(1)-bovine serum albumin conjugate withHAT-sensitive mouse myeloma cell line, P3-X63-Ag8-653. A very smallcross-reaction appeared with ginsenoside Re. The full measuringrange of the assay extends from 0.3 mug ml(-1) to 10 mug ml(-1) ofginsenoside Rg(1).

Identification of Cannabis pollens using an allergic patient's immunoglobulin E and purification and characterization of allergens in Cannabis pollens

Cannabis pollen allergens were detected using the serum of an allergic patient. The allergens were then purified by sequential column chromatography (including DE52 cellulose and phenyl-Sepharose CL-4B) and preparative HPLC. The molecular weight of the allergens were determined as 10,050 and 13,706 by matrix-assisted laser desorption/ionization time of flight mass spectrometry. We utilised Western blotting and development of an enzyme-linked immunosorbent assay for the detection of Cannabis pollen allergens.

Genetic and alkaloid analysis of Papaver species and their F1 hybrid by RAPD, HPLC and ELISA

Total DNA was extracted from the leaves of a F1 hybrid and its parents, Papaver bracteatum Lindle and P. pseudo-orientale Medw. Analysis of random-amplified polymorphic DNA (RAPD) using ten arbitrary oligonucleotide 10-mers, showed that F1 hybrid was confirmed to be genetically intermediate of both parental plants compared with the genetic distance between F1 hybrid and individual parents. Furthermore, the comparison of the band patterns between a F1 hybrid, P. bracteatum and P. pseudo-orientale clearly showed that part of the bands of both parents were induced into a F1 hybrid. The content of thebaine was determined by HPLC and ELISA used anti-thebaine monoclonal antibody.

Calicheamicin derivatives conjugated to monoclonal antibodies: determination of loading values and distributions by infrared and UV matrix-assisted laser desorption/ionization mass spectrometry and electrospray ionization mass spectrometry

Calicheamicin derivatives (MW approximately 1500) and monoclonal antibodies (MoAbs) conjugated to calicheamicin derivatives (MW approximately 150,000) were analyzed by UV-MALDI/MS, IR-MALDI/MS, and ESI/MS. These materials are potent anticancer agents. Calicheamicin derivatives and conjugates rapidly degrade upon UV irradiation but are relatively stable during IR irradiation and under ESI conditions. A unique feature of IR-MALDI/MS is a 2 times enhancement in resolution relative to UV-MALDI/MS for masses above approximately 50,000 Da resulting in a molecular ion envelope containing a series of partially resolved peaks of the calicheamicin-MoAb conjugates. The mass shift difference between the peak maxima corresponded to the mass change due to the covalent addition of calicheamicin derivatives to the monoclonal antibody. The distribution of the calicheamicin derivatives in the monoclonal antibodies was computed by deconvoluting the partially resolved peak envelope. A unique feature of the ESI mass spectra, under unit resolution conditions, is that the distribution of the carbohydrates can be well resolved for pure MoAbs and can be only partially resolved for conjugated MoAbs. Average loading values for calicheamicia derivatives when conjugated to MoAbs were computed from UV-MALDI/MS, IR-MALDI/MS, and ESI/MS data and the results compared with the average loading values obtained by UV absorption spectrometry. Very low average loading values were computed from UV-MALDI/MS data due to the degradation of the conjugated calicheamicin derivatives during the UV irradiation process. The IR-MALDI/MS average loading values, obtained with glycerol as the matrix, were consistent with the UV absorption spectrometry values for conjugates having hydrolytically stable linkers, but not when the linker contained a hydrolytically labile hydrazone. ESI/MS average loading values were generally lower than the corresponding values obtained by IR-MALDI/MS. The average loading values and distributions obtained using IR-MALDI/MS were more reliable than the corresponding ESI/MS values because the partially resolved, singly and doubly charged peaks in the IR-MALDI spectra can be mathematically deconvoluted, while the overlapping, highly multiply charged peaks of the electrospray spectra can only be partially deconvoluted.