Browsing by Author "Waibel, R."
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Item Dichapetalin M from Dichapetalum madagascariense(Elsevier B.V., 2008-08-08) Osei-Safo, D.; Chama, M.A.; Addae-Mensah, I.; Waibel, R.; Asomaning, W.A.; Oppong, I.V.The roots of Dichapetalum madagascariensis have yielded the new dichapetalin M, together with the previously reported dichapetalin A. This brings to nine, the total number of dichapetalins so far isolated from the roots of the plant, and to thirteen, the total number of dichapetalins isolated from the Dichapetalaceae. Dichapetalin M exhibited greater toxicity towards brine shrimp larvae than dichapetalin A, which has demonstrated cell inhibition against various cancer cell lines.Item The Dichapetalins - Unique Cytotoxic Constituents of the Dichapetalaceae, Phytochemicals as Nutraceuticals - Global Approaches to Their Role in Nutrition and Health(InTech Publishers, 2012) Osei-Safo, D.; Chama, M.A.; Addae-Mensah, I.; Waibel, R.Item Isolation and characterization of dipeptide derivative and phytosterol from Capparis tomentosa Lam(Scientific Research and Essays, 2008-08) Akoto, O.; Oppong, I.V.; Addae-Mensah, I.; Waibel, R.; Achenbach, H.In this study, chemical investigation of the constituents of the roots of Capparis tomentosa was carried out. C. tomentosa is a medicinal plant used extensively for the treatment of various diseases. It is also known to be poisonous. The crude petroleum ether extract of the roots of this plant was subjected to column chromatography for separation. Progress of separation was monitored by thin layer chromatography. The isolated compounds were recrystallized for further purification. The structures of these compounds were elucidated by comparison of their spectroscopic data from IR, 1HNMR, 13CNMR and MS analysis with that of authentic samples. The isolated compounds were identified as 24-ethylcholestan-5-en-3-ol a phytosterol and a dipeptide derivative, N-benzoylphenylalanylaninol acetate. This is the first time these compounds have been isolated from this plant. © 2008 Academic Journals.Item A novel D:A-friedooleanane triterpenoid and other constituents of the stem bark of Dichapetalum barteri Engl.(Arkivoc, 2007-01) Addae-Mensah, I.; Adu-Kumi, S.; Waibel, R.; Oppong, I.V.A novel pentacyclic triterpenoid, 2β-hydroxy-3-oxo-D:A-friedoolenanan- 29-oic acid has been isolated from the methanol extract of the stem bark of Dichapetalum barteri, and characterised by spectroscopic methods. Also reported for the first time from the plant are two lupane-type triterpenoids betulinic acid and betulonic acid, the friedelane triterpenoids syn:canophyllal, syn:canophyllol, friedelan-3-one and friedelan-3α-ol (epifriedelinol), the more common triterpenoids β-sitosterol and stigmasterol, as well as seven long chain esters of ferulic acid. ©ARKAT USA, Inc.