| Morinda officinalis (Bajitian in Chinese), the perennial root of Morinda officinalis How. (family Rubiaceae), is one of the famous "top four south authentic" traditional Chinese medicines (TCMs). With wide medicinal and healthy functions, it has been made into various health foods. In recent years, with the advent of "big health era", M. officinalis presents a good prospect of application and development and its efficacy and safety has become the issue of common concern. M. officinalis is planted and grown in tropical and subtropical regions, so, pesticides are used to control various diseases and insect pests for improving its production. However, because of the long cultivation period (usually 5-7 years), pesticides are more vulnerable to accumulate in this plant, leading to some threats to the safety of M. officinalis and the users’ health. Furthermore, because of direct contact with the soil for five to seven years in a warm and moist climate, it is more vulnerable to be contaminated by various fungi, resulting in mildew and multi-mycotoxin residues, seriously affecting the quality, efficacy and safety of M. officinalis.In this thesis, some powerful simple, reliable and sensitive methods were established for rapid and high-throughput detection of multi-pesticide and-mycotoxin residues and multi-chemical compositions in M. officinalis, in order to comprehensively and systematically evaluate its quality and safety. Afterwards, the growth of toxigenic fungi, the cumulation of mycotoxins and the content changes of chemical components were studied with the aid of response surface analysis-central composite design, and then the storage specification for scientific preservation of M. officinalis was summarized to provide theoretical basis and data support for safety evaluation, reasonable maintenance of this TCM to ensure its quality and efficacy, safety. The main contents were as follows:1. Modified QuEChERS with GC-FPD method for simultaneous determination of organophosphorus pesticide residues in Morinda officinalisAfter optimization of various conditions of sample pretreatment, forty batches of M. officinalis samples was extracted with acetonitrile:water (9:1, v/v) and cleaned up with PSA and GCB for rapid analysis of 30 organophosphorus pesticides (OPPs) by using gas chromatography with flame photometric detection (GC-FPD) method. Results showed that two samples (5%) from the same origin were contaminated with organophosphorus pesticide residue (fenitrothion) at concentrations of 0.028 mg/kg and 0.035 mg/kg, which were higher than the MRL (0.02 mg/kg) suggested by the European Union (EU). A rapid and accurate method with high sensitivity, low limits of detection, high precision and good repeatability was developed, providing references for the analysis of pesticide residues in other root-stock medicinal materials.2. ASE/MSPD-GC-ECD for simultaneous detection of organochlorine and pyrethroid pesticide residues in Morinda officinalisExtraction temperature, solvent and the amount of Florisil was optimized by orthogonal experimental design to optimize the extraction condition of accelerated solvent extraction assisted matrix solid phase dispersion (ASE/MSPD) method for 33 organochlorine pesticides (OCPs) and 9 pyrethroid pesticides (PYPs) by gas chromatography-electron capture detection (GC-ECD). Four kinds of pesticides (beta-endosulfan, tecnazene, hexachlorobenzene and alpha-BHC) were detected in three batches of samples, with the concentrations conformed to the legislation of the EU. The developed method was simple and rapid with high degree of automation and good repeatability, which can be extended to detect organochlorine and pyrethroid pesticide residues in other complex matrices.3. Simultaneous analysis and identification of multi-class mycotoxins in Morinda officinalis by UFLC-ESI-MS/MSUsing water/methanol (20:80, v/v) both containing 0.1% formic acid as the extraction solvent, samples was pretreated by one-step procedure. After optimization of chromatographic and mass spectromic parameters, ultra fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method was developed for simultaneous quantitationn and quantification of 11 mycotoxins in 40 batches of M. officinalis samples, based on scheduled multiple reaction monitoring (sMRM) acquisition mode. Results showed that 2 out of 40 samples were contaminated with Citrinin (CIT), fumonisin and aflatoxins (AFB1, AFB2, AFG1 and AFG2) with residual levels below the regulatory MRLs suggested by the EU. The developed method with high sensitivity, good selectivity and repeatability, high recovery and efficiency was suitable for rapid analysis of multi-mycotixins in complex matrix of M. officinalis.4. Quantitation of iridoid glucosides and establishment of chemical fingerprint by HPLC-DAD for quality control of Morinda officinalisM. officinalis Samples was prepared by ultrasonic extraction. Two main iridoid glucosides were quantified and the chemical fingerprints of 40 batches of M. officinalis samples were established by high performance liquid chromatography-diode display detection (HPLC-DAD). Afterwards, the obtained experimental data was parsed by the chemometric methods including similarity analysis, hierarchical clustering analysis, principal component analysis and partial least square-discrimination analysis provide research foundation for quality control of M. officinalis.5. Investigation on the optimal storage conditions of Morinda officinalis based on response surface analysis-central composite design (RSM-CCD) method and "trans-cultivation" mode for the establishment of storage specificationUsing Aspergillus flavus 3.4410 as the model toxigenic fungi, the sterilized M. officinalis was infected with the fungi and then was stored under different environmental conditions at different temperature and humidity for "trans-cultivation". After storage, the contents of iridoid glucosides and four aflatoxins (AFB1, AFB2, AFG1 and AFG2) in M. officinalis were quantified by HPLC-DAD and UFLC-ESI-MS/MS respectively. The growth of the fungi, the contents of main chemical components and aflatoxins in M. officinalis stored at different temperature and humidity conditions was investigated through response surface analysis-Central composite design (RSM-CCD) to discuss the optimal environmental condition to prevent the production of mildew and aflatoxins, providing theoretical basis and data support for the establishment of storage specification to ensure the efficacy and safety of M. officinalis. |
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