Browsing by Author "Sarfo, Agyemang Derkyi"

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    Phytochemical screening, brine shrimp lethality test and pesticidal action of some indigenous plants
    (2000) Sarfo, Agyemang Derkyi
    An attempt has been made at establishing the scientific basis for the traditional use of Some Ghanaian plant products as pest control agents for stored food grains. Samples (leaves/seeds) of fifteen different plants were collected, dried and ground into tine powders. Extractions were performed using pet-ether and ethanol as solvents. Steam distillation was also used to obtain the oil from Cymbopogan winterianus leaves. The brine shrimp lethality bioassay was used to determine the toxicities of the extracts, by estimating the LC50 values. Toxicities of Cymbopogan winterianus(oil), Azadirachta indica(oil), Cassia alataa(ethanol extract) and Allium sativum(slurry ) were very high whilst toxicities of Jatropha curcas(ethanol extract), Celtis mildbraedii(ethanol extract) and Blighia sapida( pet-ether extract) were very low. Studies on the influence of eight of the plant extracts and one synthetic insecticide on the storage of cowpea and maize seeds for three months were conducted at the Crops Research Institute, Kumasi. The results indicated that some plant extracts had significant effects on the total number of insects (Callosobruchus rnaculates/Sitophilus zeamais) killed (highest for Cvmbopogan winterianus) damaged seeds (highest for Griffornia simplicifolia. no damage for Cymbopogan winterianus) and population build-up (least for Cymbopogan winterianus) and could compare to synthetic insecticides. From phvtochemical studies, the plants showed different classes of secondary plant metabolites. Chromatographic studies on the ethanol extract of Cassia alata leaves produced four fractions P1, P2, P3 and P4. Fractions p1 and p3 isolated were chemically found to the carotenoids. Fraction p2 was chemically found to be a triterpenoid whilst fraction P4 was chemically found to be an anthraquinone.