oa Editorial [Hot Topic: New Strategy for Drug Discovery Using Monoclonal Antibody (Guest Editor: Yukihiro Shoyama)]

The authors in this thematic issue provide a comprehensive summary of most recent knowledge on the relation of natural products and monoclonal antibody (MAb) in order to expand the new technologies for drug discovery. Although MAbs are now indispensable in the biological field, they are rare phytochemical research areas except naturally occurring therapeutic medicines like morphine, taxol and vinblastine and so on because the preparation of MAb against naturally occurring bioactive compounds is not so easy depending on the complex structure and they cannot determine hapten molecule. Therefore, first we opened the determination methodology of hapten molecule number in the carrier protein conjugate by MALDI-tof mass. From this success we have been accumulating many MAbs that resulted to make it possible to create new methodologies such as [eastern blotting], [knockout extract] and [missile type molecular breeding]. In this thematic issue we will be able to cover the wide phytochemical fields from the quality control of traditional Chinese medicine (TCM) to the biotechnology using compact MAb gene for medicinal plant breeding regarding bioactive components. Quality control and standardization of the medicinal plants and/or the traditional Chinese medicine (TCM) are necessary factors affecting the difference of chemical constituent to the composition and concentration, many reasons such as genetic distinction, botanical sources, production area, harvest time, processing method, etc. are also considered. Quality control of the medicinal plants and/or TCM by using MAb is quick, without any pre-treatment, very small scale, reproducible and soft for circumstances as they do not need organic solvent compared to HPLC analysis. For example, ELISA kit for glycyrrhizin contained in licorice is now available in the market. The immunoblotting method is based on western blotting technique that utilizes antigen-antibody binding properties and has been developing a specific and sensitive detection of higher molecule analyte like peptides and proteins. Despite being impossible against small molecular compounds, a new immuno-staining method for natural glycosides has been developed and named as eastern blotting. This new methodology may open a new field of the quality control for natural products, therefore this methodology will be incorporated in this thematic issue. Eastern blotting can stain only hapten molecule on membrane. TLC plate developed will be covered by PVDF membrane, followed by treatment of the membrane with sodium periodide and further, the addition of carrier protein like BSA. The membrane will initially be treated by MAb and then the secondary antibody modified by the enzyme. Finally, a substrate will be added resulting in staining. In this case we succeeded to stain glycosides having sugar linkage in a molecule like ginseng saponins, solasodine glycosides, glycyrrhizin and so on. Moreover, the polyethersulphone (PES) membrane is also available. There is no need to develop TLC as it is possible to investigate the quantitative analysis by using NIH imaging soft. Glycosides are complicated and can not be elucidated automatically like amino acid analysis and the DAN sequencing results show that the structure elucidation of glycosides needs much efforts. Application of the double staining of eastern blotting for the ginseng saponins can suggest the structure of unknown ginseng saponins, depending on the staining color related to the aglycone and the Rf value related to the sugar number. Recently, without the affinity purification of proteins the promotion of almost all investigations might be impossible. But the succees of immunoaffinity purification against small molecule compounds is almost nothing until now. Knockout extract can be prepared by the elimination of only an antigen molecule from the crude extract by an immunoaffinity column. More over, an immunoaffinity concentration of glycoside can function for the exact determination of concentration for important glycosides even though at very lower concentration. This newly developed knockout extract evidently demonstrated the real bioactive compound contained in the extract of crude drug. Therefore, we incorporated three applications for ginseng, licorice and American ginseng in this thematic issue. Technology of compact MAb has been expanding and accumulating in the field of cancer therapy. However, the natural products having small molecule are rare therefore, a review has been planned to introduce the important natural products. In general, many attempts of increasing secondary metabolites by the stimulation of biosynthetic enzyme related to the natural products have been investigated, but no success has been reported so far. In this thematic issue one application of technology of compact MAb, single chain fragment-variable (scFv) antibody named as [missile type molecular breeding] is incorporated for the breeding of solasodine glycoside producing plant. In this case, if the MAb against a target molecule is available, the construction would be simple and quick. This way it resembles with the neutralizing antibody for cancer therapy. In this issue of Current Drug Discovery Technologies, seven reviews have been incorporated and highlighted in detail related to MAbs. It can be evaluated that the evidences reviewed in this issue may be applied widely in the field of drug discovery. Moreover, more than 260 references found at the end of the individual reviews, will make this thematic issue useful not only for phytochemical researchers but also for many scientists working in the numerous fields of natural products, emphasizing the high scientific standing of the issue.