Comparative investigation of two different self-organizing map-based wavelength selection approaches for analysis of binary mixtures with strongly overlapping spectral lines

Purpose: To demonstrate the ability and investigate the performance of two different wavelength selection approaches based on self-organizing map (SOM) technique in partial least-squares (PLS) regression for analysis of pharmaceutical binary mixtures with strongly overlapping spectra.Methods: Two different variable selection methods were compared, namely, SOM1-PLS and SOM2- PLS. The main difference between these methods involved the structure of neurons in input layer and the algorithm for variable selection. Adjustable parameters for each technique were optimized for better comparison. The performance of these methods was statistically verified for predictive ability using both synthetic mixtures and a real combination product of sulfamethoxazole (SMX) and trimethoprim (TMP), which exhibited strongly overlapping of spectral lines.Results: The results obtained indicate that SOM2-PLS was more efficient than SOM1-PLS technique with 30 and 6 % improvement in predictive ability for SMX and TMP, respectively. Furthermore, the mean difference between the results obtained from SOM2-PLS method and those from the official method was not statistically significant as p-value was more than 0.01.Conclusion: Although, SOM2-PLS method is more efficient than SOM1-PLS method for the analysis of pharmaceutical binary mixtures with severely overlapping spectra, some problems associated with SOM2-PLS technique include difficult computations of some parameters.Keywords: Co-trimoxazole, Self-organizing map, Wavelength selection, Pharmaceutical analysis, Overlapping spectral line

Thiolated pectin–doxorubicin conjugates: Synthesis, characterization and anticancer activity studies

© 2017 Elsevier Ltd In this paper, pectin was cross-linked by a coupling reaction with either thioglycolic acid or cystamine dihydrochloride to form thiolated pectins. The thiolated pectins were then coupled with doxorubicin (DOX) derivative to obtain thiolated pectin–DOX conjugates by two different methods, disulfide bond formation and disulfide bond exchange. The disulfide bond exchange method provided a simple, fast, and efficient approach for synthesis of thiolated pectin–DOX conjugates, compared to the disulfide bond formation. Characteristics, physicochemical properties, and morphology of thiolated pectins and thiolated pectin–DOX conjugates were determined. DOX content in thiolated pectin–DOX conjugates using low methoxy pectin was found to be higher than that using high methoxy pectin. The in vitro anticancer activity of thiolated pectin–DOX conjugates was significantly higher than that of free DOX, in mouse colon carcinoma and human bone osteosarcoma cells, but insignificantly different from that of free DOX, in human prostate cancer cells. Due to their promising anticancer activity in mouse colon carcinoma cells, the thiolated pectin–DOX conjugates might be suitable for building drug platform for colorectal cancer-targeted delivery of DOX