Phytochemical studies of botanicals: Hoodia gordonii and Caralluma species

Two succulent plants, Hoodia gordonii and Caralluma fimbriata are studied in the present dissertation work. Both of these plants are traditionally used by the tribal people in S. Africa and India, respectively, as appetite suppressant and famine food. Overall objective of the present research was to generate some fundamental information about these two botanicals, and to obtain scientific substantiation towards the efficacy and quality of botanical supplements containing these two succulent herbs. Chapter one of this dissertation consists of a brief review of the background information about significance of plants as sources of food as well as medicines. Use of plants as botanical supplements to achieve health benefits and the issues surrounding the efficacy, quality and safety of such botanical supplements are discussed in this chapter.;Chapter two discusses the phytochemical study of Hoodia gordonii that resulted in isolation of several pregnane glycosides. Twenty-eight new constituents (hoodigoside A-Z, hoodistanaloside A and B) were isolated and characterized as a part of this study. Further, chapter two also encompasses an X ray diffraction study of hoodigogenin A, and aglycone from H. gordonii. Evaluation of biological activities of the constituents obtained from H. gordonii is also discussed in chapter two. The aforementioned glycosides did not show cytotoxicity, antioxidant activity and estrogenic activity. The novel pregnane glycosides isolated during the presented research were used as markers for standardization of botanical raw materials and marketed products. An HPLC and LC-MS enabled quality control method is described in chapter three, which made use of P57, the proposed active constituent of H. gordonii, as the marker compound. Authentication of Hoodia raw materials and marketed botanical supplements is discussed in this chapter. The results discussed in chapter three were based on presence or absence of P57 and quantitative analysis of P57 content in the tested samples. Further, the standardization of various Hoodia raw materials as well as botanical products was achieved by using 11 oxypregnane glycosides as markers. Results of this study are discussed in chapter four. P57 was found to be present in three of the Hoodia species. The accuracy, precision, linearity and limit of detection were determined to validate the method.;Chapter five describes a phytochemical study of a species of Caralluma genus. Caralluma adscendens var. fimbriata, which is also known as "Indian Hoodia", has gained popularity as an appetite suppressant. Phytochemical investigation of a commercially available Caralluma sample was undertaken in order to generate better understanding of the chemical constitution of this species and to develop marker constituents for development of quality control methods. The chromatographic separation of methanolic extract of Caralluma species resulted in isolation of one new pregnane glycoside (carallumoside A) and seven known steroid derivatives namely, caraumbellogenin, carallumoside B, boucerin, caraumbelloside I, II, and III, and boerharigenin B. Most of the known compounds were previously reported from other species of Caralluma genus. Chromatographic comparison with an authentic C. fimbriata plant material obtained from India indicated that the commercial sample used for the phytochemical study may not be that of C. fimbriata.;Chapter six presents an HPLC method that was developed for quality analysis of botanical supplements, which claim to contain Caralluma fimbriata , and to differentiate between Caralluma and Hoodia. The results of this study demonstrate that chromatographic profiles of Hoodia and Caralluma are distinctly different from each other and the present method can be used to identify presence of Hoodia and Caralluma in the respective botanical products. Botanical supplements analyzed during this study showed the presence of marker compounds isolated from Caralluma species.;In order to verify our hypothesis that Hoodia gordonii and Caralluma fimbriata can act as appetite suppressants by activation of peroxisome-proliferation activated receptors (PPAR), we tested the compounds isolated from these two botanicals, for their potential to induce activation of PPAR-alpha and PPAR-gamma receptors in CHO cells. Results of this bioactivity study are discussed in chapter seven. These results demonstrate that some of the isolated pregnane glycosides have potential to induce PPAR-alpha receptor. Further studies to justify the structure-activity relationship and mechanism of binding of the active compounds to PPAR-alpha are warranted in future.