Browsing Journal Articles (PAS) by Author "Opiyo, Sylvia A."
Now showing items 1-20 of 45
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7a-Acetylugandensolide and antimicrobial properties of Warburgia ugandensis extracts and isolates against sweet potato pathogens
Opiyo, Sylvia A.; Manguro, Lawrence O.A.; Okinda-Owuor, Philip; Ateka, E.M.; Lemmen, Peter (Elsevier, 2011)7a-Acetylugandensolide together with thirteen known drimane-type sesquiterpenes have been isolated from Warbugia ugandensis bark extracts. Their structures were established by spectroscopic and physical methods as well as ... -
Analgesic Activity of Conyza Floribunda Extracts in Swiss Albino Mice
Opiyo, Sylvia A.; Muna, Kennedy K.; Ndirangu, Ephantus G. (2021-06-30)Traditional medicine still plays an important role in managing infections especially in Africa. Extracts of Conyza floribunda Kunth are used to treat sore throat, ringworm and other skin related infections, toothache and ... -
Analgesics from Lonchocarpus eriocalyx Harms
Ochung, A. A.; Owuor, P. O.; Manguro, L. A..O.; Ismael, I. O.; Nyunja, R. A.; Ochieng, C. O.; Opiyo, Sylvia A. (2018-12) -
Antimicrobial Activity of Root Bark Extracts of Rhus natalensisa and Rhus ruspolii
Njoroge, Peter W.; Opiyo, Sylvia A. (Scientific & Academic Publishing, 2019-08)Bacteria and fungi are frequent causes of serious opportunistic infections worldwide. Several effective antibiotic drugs are in the market. However, drug-resistance, side effects and cost of such antibiotics limits their ... -
Antimicrobial Compounds from Terminalia brownii against Sweet Potato Pathogens
Opiyo, Sylvia A.; Manguro, Lawrence O.A.; Owuor, Philip O.; Ochieng, Charles O.; Ateka, E.M.; Lemmen, Peter (Bentham Science Publishers, 2011)Phytochemical evaluation of Terminalia brownii extracts led to the isolation of five compounds namely - sitosterol, stigmasterol, monogynol A, betulinic acid and arjungenin. Their structures were established by spectroscopic ... -
Antimicrobial Constituents Of Conyza Floribunda
Opiyo, Sylvia A.; Manguro, Lawrence O.A. (WebmedCentral, 2010-09)The study describes the antibacterial and antifungal effects of both CH2Cl2 and MeOH crude extracts, collected fractions and pure isolates of Conzya floribunda. The antimicrobial activity tests were carried out using agar ... -
Bioactive carbazole alkaloids from Alysicarpus ovalifolius (Schumach)
Ochung, Angeline Atieno; Manguro, Lawrence Arot Oyango; Owuor, Phillip Okinda; Jondiko, Isaac Ogoche; Nyunja, Regina Achieng; Akala, Hosea; Mwinzi, Pauline; Opiyo, Sylvia A. (CrossMark, 2015)Phytochemical and biological evaluation of the stem bark of Alysicarpus ovalifolius led to the isolation of three carbazole alkaloids identified as mohanimbine (1), koenimbine (2) and koenidine (3) along with quercetin ... -
Bioactive Constituents of Conyza floribunda
Opiyo, Sylvia A.; Manguro, Lawrence O.A.; Ogur, Joseph A.; Wagai, Samuel Otieno (Medwell Journals, 2010)The study describes the antibacterial and antifungal effects of both CH2Cl2 and MeOH crude extracts, collected fractions and pure isolates of Conzya floribunda. The antimicrobial activity tests were carried out using agar ... -
Biopesticidal Extractives and Compounds from Warburgia Ugandensis against Maize Weevil (Sitophilus zeamais)
Opiyo, Sylvia A.; Manguro, Lawrence O.A.; Akinyi, Dorothy; Ochung, Anjeline A.; Ochieng, Charles O. (Bentham Science Publishers, 2015)Agricultural production is constrained by insect pests, which cause serious post-harvest losses of up to 43% in developing countries. Maize weevil (Sitophilus zeamais Motschulsky.) is one of the most destructive pests of ... -
Characterization of Clays from selected sites for Refractory Application
Lomertwala, H. M.; Njoroge, Peter W.; Opiyo, Sylvia A.; Ptoton, Brian M. (2019-11)Clay is a stony or earthy mineral aggregate composed of fine-grained minerals, which are plastic at appropriate water content and hardens up when fired. Clay soils have various mineral groups such as kaolinite, smectites, ... -
Characterization of Immunogenic Soluble Crude Proteins from Biomphalaria Pfeifferi Against Schistosoma mansoni
Kuria, Kennedy M.; Opiyo, Sylvia A. (2020-06-30)Schistosomiasis is the second most prevalent tropical disease in the world after malaria. Chemotherapy and molluscicides which are the main methods of control do not give lasting protection as the disease continues to ... -
Chemical Composition And Biological Activity Of Extracts From Conyza Species
Opiyo, Sylvia A.; Njoroge, Peter W.; Kuria, Kennedy M. (iosrjournals.org, 2023-04)The genus Conyza (Asteraceae) comprises about 50 species and found in the tropical and warm regions. Extracts from Conyza species have numerous pharmacological applications. The aim of this study was review the chemical ... -
Chemical composition and repellency of Nigella sativa L. seed essential oil against Anopheles gambiae sensu stricto
Ndirangu, Ephantus G.; Opiyo, Sylvia A.; Ng'ang'a, M. W. (2020-04)Malaria which is caused by the Plasmodium parasite and transmitted through bites of infected female Anopheles mosquitoes is an important public health concern in Africa. Insect repellents are commercially available but ... -
Chemical Composition of Essential Oils from Ocimum Kilimandscharicum: A Review.
Opiyo, Sylvia A. (IOSR Journal of Applied Chemistry (IOSR-JAC).Volume 15, Issue 11 Ser. I (November 2022), PP 05-11, 2022)Traditional medicine plays an important role in disease especially in developing countries. The essential oils of Ocimum species showed anti-oxidant, anti-inflammatory, anti-cancer and insecticidal activities. Essential ... -
Chemical Constituents of Essential Oils from Three Eucalyptus Species Acclimatized in Ethiopia and Kenya
Manguro, L. A. O.; Opiyo, Sylvia A.; Asefa, A.; Dagne, E.; Muchori, P. W. (2014-11)Essential oils obtained by steam distillation of three Eucalyptus species acclimatized in Ethiopia and Kenya were analyzed using GC and GC-MS. The species were Eucalyptus citriodora, Eucalyptus globulus and Eucalyptus ... -
Chemical Constituents of Ocimum Kilimandscharicum Guerke Acclimatized In Kakamega Forest, Kenya
Makenzi, A. M.; Manguro, L. O. A.; Owuor, P. O.; Opiyo, Sylvia A. (Chemical Society of Ethiopia, 2019-10)The genus Ocimum belongs to the Lamiaceae family and is made of almost 200 species of herbs and shrubs which have potential medicinal properties. The species are native to the tropical and temperate climate zones around ... -
Cyclooxygenase inhibitory compounds from Gymnosporia heterophylla aerial parts
Ochieng, Charles O.; Mureka, Edward W.; Ishola, Ismail O.; Opiyo, Sylvia A. (Elsevier, 2017)Gymnosporia heterophylla (Celastraceae) is an African medicinal plants used to treat painful and inflammatory diseases with partial scientific validation. Solvent extractions followed by repeated chromatographic purification ... -
Development of a multiplex PCR technique for simultaneous detection of sweet potato feathery mottle virus and sweet potato chlorotic stunt virus
Opiyo, Sylvia A.; Ateka, E.M.; Owuor, P.O.; Manguro, L.O.A.; Miano, D.W. (Edizioni ETS Pisa, 2010)Virus diseases, especially those caused by mixed infections, are among the economically most devastating diseases of sweet potato. Sweet potato virus disease (SPVD), which is caused by mixed infection of Sweet potato ... -
Effect of Acid Treatment on the Chemical Properties of Clays from Selected Sites in Murang’a and Nyeri counties, Kenya
Lomertwala, Hassan M.; Njoroge, Peter W.; Opiyo, Sylvia A.; Ptoton, Brian M. (2020-11-30)Assessing improvement on the quality of clay has been conducted by treatment with different concentrations of hydrochloric and oxalic acid. This project intended to assess the effect of acid treatment on the elemental ... -
Evaluation of Warburgia ugandensis Extracts and Compounds for Crop Protection against Prostephanus truncates
Opiyo, Sylvia A. (2020-11)Insect pests cause a significant loss of maize production in Africa. Maize weevil (Sitophilus zeamais Motchulsky) and the larger grain borer (Prostephanus truncatus Horn) are the most destructive insect pests of maize. ...