Doctoral Thesis / Dissertation from the year 2010 in the subject Chemistry - Bio-chemistry, , language: English, abstract: In this study four plants (Chrozophora hierosolymitana Spreng, Chrysanthemum leucanthemum L., Ephedra gerardiana Wall. ex Stapf and Quercus dilatata L.) collected from different regions of Pakistan were screened to identify any chemotherapeutic agentspresent in them. Seven crude extracts of these plants (leaf, stem and root extracts of C. hierosolymitana, aerial parts of C. leucanthemum, stem and root extracts of E. gerardiana and aerial parts of Q. dilatata) were examined for antimicrobial activity using agar diffusion method and agar tube dilution method, cytotoxicity using brine shrimp assay, antitumor activity using potato disc assay, phytotoxic activity using radish seed bioassayand antioxidant activity by using DPPH radical scavenging assay and free radical induced oxidative DNA damage assay.Two plant extracts of C. hierosolymitana and Q. dilatata showed antibacterial activity. Two plant extracts of E gerardiana and C. leucanthemum showed antifungal activity. Two plant extracts i.e., leaf extract of C. hierosolymitna and root extract of E.gerardiana showed significant brine shrimp cytotoxicity activity (IC50 171.55 to 523.8 ppm). Six of the seven extracts exhibited tumor inhibition at all the three concentrations tested ranging from 10 to 80%. All extracts showed significant plant growth and seedgermination inhibition at higher concentrations against radish seeds. Two extracts of C.hierosolymitana and Q. dilatata showed growth stimulating effects at lower concentrations. Two extracts of C hierosolymitana and Q. dilatata showed significant DPPH radical scavenging activity (IC50 10.52 to 45.9 ppm). Three of the seven extracts i.e., (R) E. gerardiana, (A) Q. dilatata and (A) C. leucanthemum showed DNA protection activity at 100 and 10 ppm while at 1000 ppm showed no DNA protection activity while rest of the four extracts showed DNA protection activity at all the three concentrations tested. Phytochemical tests showed presence of alkaloids, saponins, anthraquinones, terpenoids, flavonoids, flavones, tannins, phlobatannins and cardiac glycosides at varyinglevels in these extracts.[...]