| Traditional Chinese medicine(TCM)Schizonepeta tenuifolia(S.tenuifolia)is the dry above-ground part of a Lamiaceae family plant Schizonepeta tenuifolia Briq.Utilizing the research concept and methods of TCM resource chemistry,this dissertation provided scientific evidence for the standardized manufacture and effective application of S.tenuifolia by investigating the optimum harvest,pretreating,storage,and product specification of S.tenuifolia.This dissertation mainly comprises five chapters,including literature review,and studies on the optimum harvest time,quality change model,storage suitability,and decoction tablet classification of S.tenuifolia.1 Literature reviewThis chapter first provided references for studies regarding the resource,production,circulation and storage of S.tenuifolia by systematically investigating the status quo of the harvest,pretreating,storage and commercial decoction tablets of TCM materials,and by summarizing previous experiences and clinical outcomes.Meanwhile,this chapter lays sound foundation for future relevant studies by systematically analyzing the historical evolution,Materia Medica,clinical use and worldwide resource chemistry of S.tenuifolia.2 Optimum harvest time of S.tenuifolia2.1 Changes of different index components of S.tenuifolia during harvestThe volatile oils,four essential monoterpenes(menthone,limonene,pulegone and menthofuran)and four types of other volatile components in the leaves and spikes of S.tenuifolia harvested at different time courses were determined by GC-SIM-MS for the first time.The results show that from pre-flowering stage to fruiting stage,the contents of menthone in leaves and spikes gradually increased and decreased respectively,while those of limonene did not differ obviously.The contents of pulegone and menthofuran in leaves both dramatically reduced,whereas those in spikes both increased.Besides,the contents of 1-octen-3-ol,3-octanone,β-myrcene andβ-caryophyllene remained constant throughout the harvest.The contents of ursolic acid and oleanolic acid in S.tenuifolia harvested at different time courses were determined by HPLC,which did not vary apparently from pre-flowering stage to early-flowering stage,significantly rose to maximum during the full-flowering stage,and decreased after entering the fruiting stage.The contents of total flavonoids in S.tenuifolia harvested at different time courses,which were measured by UV-vis spectroscopy,increased and then decreased overall,and peaked during the full-flowering stage.2.2 Multiple-index comprehensive evaluation on the optimum harvest timeA weighting scale involving different harvest time courses was obtained by assigning different weighting coefficients after analyzing the changes of multiple-index components throughout the growth via the subjective weighting method,showing that the scores differed significantly at seven harvest time points.In the pre-flowering stage,the leaves of S.tenuifolia grew prosperously without spikes,thus rendering volatile oils and indices to stem from leaves.Meanwhile,the contents of all components were relatively low with the weighting score of 78.559.In the early-flowering stage,the contents of volatile oils and the components therein were obviously elevated because the emergence of only a few spikes atop and numerous gradually growing inflorescences.However,the contents of non-volatile components did not fluctuate evidently,with the weighting scores ranging from 75.892 to 78.644.The weighting score of the full-flowering stage was 84.093,during which considerable spikes grew and flowers bloomed atop,producing a small number of seeds.With elapsed time in the fruiting stage,major inflorescences produced seeds that gradually matured,which was accompanied by increasing falling leaves,leading to the weighting scores ranging between 83.406 and 89.282.The multiple-factor results suggest that the qualities of each component in the midst of full-flowering stage(mid-September)and fruiting stage(early October)were similar and uniformly distributed,yielding high-quality S.tenuifolia.Given that optimum plants were harvested in their full-flowering stage,traditional harvest protocol was verified rational by meeting the requirements of "plants grow optimally upon flowering".3 Dependence of quality on drying process3.1 Drying process of S.tenuifoliaThe influences of drying time,drying temperature and initial water content on the contents of pulegone as the pharmacological component of S.tenuifolia in dried samples were tested.This content was lowered either at higher drying temperature for longer time,or at the same temperature for identical time while starting from higher water content therein.An orthogonal experiment was designed according to the single-factor analysis results.The resultant data were subjected to analysis of variance,based on which optimum drying conditions were selected(50℃,3h,60.89%d.b)from the viewpoint of time-and cost-saving.3.2 Dynamics study on the dependence of quality on drying processThe content of pulegone changed following a first-order kinetic equation(n=1)on the basis of static isothermal and isohumidity experimental data(R2=0.9651).All the Q,M,T and t values derived from the orthogonal test were linearly fitted(R=0.7362)by MATLAB7.8.0 to determine parameters K0,a1 and a2 in the equation,yielding a kinetic model for the mass change of pulegone eventually.Q=Q0·expl[-0.42·exp(-286.34+1.37M/RT)·t]The well matched simulated and experimental data allowed the model to satisfactorily reflect the relationship between mass change and factors such as temperature and time.In the model,higher Q0 resulted in higher content after drying,increasing T sharply decreased the content,decreasing M also lowered the content,and elevating t led to lower content.4 Effects of storage methods on the quality of S.tenuifoliaS.tenuifolia dried on site were packaged by two materials and stored by four methods,which were compared to explore the impact of storage conditions on the contents of volatile and non-volatile pharmacological components in 12 months to find out the optimum protocols.Unlike ventilated storage with conventional gunny sack package at ambient temperature that failed to preserve the products for long time,low-temperature storage with vacuumized plastic package in dark functioned better.5 Decoction tablet classification of S.tenuifoliaReferring to the quality standards of S.tenuifolia decoction tablets stipulated in the 2010 edition of Chinese Pharmacopoeia,22 batches of commercial products were collected and prepared into 7 batches of samples,and the contents of total ash,acid-insoluble ash,volatile oil and pulegone,as well as triterpene acids and flavonoids were measured.Triterpene acids and flavonoids were not enrolled in the classification standards owing to ubiquitous distribution of them in all batches catering to the technical requirements of characteristic spectra without inter-batch variability.The limit values of total ash,acid-insoluble ash,volatile oil and pulegone were specifically stipulated.Moreover,an item of stem ratio of S.tenuifolia was recommended,with which decoction tablets were classified as superb(<70%)and Class Ⅰ(<85%)respectively.To preserve genuine producing areas,decoction tablets prepared from S.tenuifolia in Anguo,Heibei were recommended as superb. |
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