Phytochemical and Biological Investigations on Medicinal Plants from Pakistan

During the current project three medicinal plants from Pakistan were investigated for their phytochemical constituents and biological activities. These medicinal plants were selected based on the fact that they were used traditionally for the treatment of diabetes mellitus and microbial infections by local people. Also the traditional healers use them in formulations which are based on the "Ayurveda", "Unani" or "Tib" medicinal systems of the Indian subcontinent.;From Nymphoides indica leaves extracts a series of seco-iridoids and flavonoids was isolated. All crude extracts, fractions and compounds were tested for a number of biological activities. We were able to conclude that the extracts possessed moderate antimicrobial and antidiabetic activities. It was emphasised that the phenomenon of synergism and of metabolic conversions of constituents after oral intake may explain its traditional medicinal use, in spite of rather moderate in vitro activities.;For Kickxia ramosissima, we were able to isolate some iridoids and flavonoids, which were tested for various biological activities. It could be concluded that the crude extracts, fractions and isolated compounds presented some promising activities including antidiabetic effects, for which the plant is known. Similarly to N. indica, synergistic effects and the occurrence of many glycosylated compounds that are metabolised after oral intake could possibly play a key role in the pharmacological activity of Kickxia ramosissima.;Finally some coumarin-sesquiterpenes were isolated from the Ferula narthex exudate. Based on our findings, it was hypothesize that the isolated constituents may contribute in part to the traditional use of Ferula narthex in diabetic conditions and for antimicrobial applications. As we were able to present some antiprotozoal and antiAGEs compounds, further detailed investigations are suggested for in vivo blood glucose lowering effects and a broader screening for antimicrobial analysis.;Although no highly active constituents have been identified, this study has contributed to the phytochemical and biological knowledge of three medicinal plants widely used in Pakistan. The results of the present investigation may in part support their traditional use against microbial infections and/or in diabetic conditions. Especially for Nymphoides indica and Kickxia ramosissima, the possibility that prodrugs such as iridoid- and flavonoid glycosides, showing weak in vitro activities, are deglycosylated and metabolically activated after oral administration, cannot be excluded, and should be investigated in more detail. As indeed in vitro assays cannot really mimic in vivo situations, we suggest further in vivo trials of isolated constituents and the crude extracts.