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University of Karachi (2016)

CHEMICAL FINGERPRINTING OF FAGONIA INDICA AND MEDICINALLY IMPORTANT LICHEN SPECIES

KANWAL, NAYAB

Titre : CHEMICAL FINGERPRINTING OF FAGONIA INDICA AND MEDICINALLY IMPORTANT LICHEN SPECIES

Auteur : KANWAL, NAYAB

Université de soutenance : University of Karachi

Grade : Doctor of Philosophy (PhD) 2016

Résumé
This Ph. D. dissertation is divided into eight chapters. The first four chapters focus on the introductory essays while last four chapters comprise the research work conducted. Brief history of chemical fingerprinting of medicinal plants using different chromatographic and mass spectrometric techniques is summarized in first chapter. Second chapter based on the types, theory and applications of mass spectrometry in phytochemical analysis. A brief account of traditional medicinal importance of genus Fagonia is summarized in chapter three. The fourth chapter summarizes the medicinal importance, qualitative and quantitative analysis of lichen metabolites in different lichen species. HPTLC and UPLCMS/MS chemical fingerprinting methods of different samples of Fagonia indica are discussed in chapter five. Total thirteen compounds were putatively identified with the help of UPLC-MS/MS. Six saponins including five new (1-5) and one known (6) compounds were also isolated from crude extract of F. indica and fully characterized with the help of advance spectroscopic techniques. Compound 6 seems to exert distal to the KATP and Ca2+channels, coupled with stimulatory glucose concentration. Due to medicinal importance of Fagonia indica, we established a fast, sensitive, accurate procedure for simultaneous quantification of total six non-sulphonated and sulphonated triterpenoid saponins and summarized in chapter six. The developed method is based on the multiple reaction monitoring (MRM) quantification using LC-QQQ-MS instrument. The results indicate that the samples from different locations share a similar HPLC pattern however the amount of six compounds in samples vary greatly. In seventh chapter of the thesis, structure-fragmentation relationship of ten metabolites of Lichens species belonging to various chemical classes were studied using -ve mode of electrospray quadrupole time-of-flight mass spectrometry (ESI-Qq-TOF-MS/MS). Fragmentation pattern of standard compounds, high resolution analysis and database were used for the quick identification of secondary metabolites in two lichen species, Parmotrema grayana and Heterdermia obscurata. Total fifteen compounds were identified from the methanolic and dichloromethane extracts of Parmotrema grayana, and Heterdermia obscurata. The eighth chapter of this dissertation explains an accurate, simple and sensitive stabilityindicating TLC densitometric method for quantification of glycyrrhetic acid and its degradation product as recommended by the ICH guidelines. Results of this study showed that glycyrrhetic acid is stable under basic, neutral, oxidative, dry heating and wet heating conditions but, it was degraded under acidic and photochemical conditions. Moreover, fragmentation pattern of glycyrrhetic acid was developed employing ESI-qTOF-MS/MS in positive mode. The photo-degraded product formed was characterized through comparison of mass spectrometric studies with glycyrrhetic acid.

Présentation (Pakistan Research Repository)

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Page publiée le 17 mai 2019