Biomedical subjects
Publications and source records attributed to Leslie J Harrison.
Microbial transformation of the sesquiterpenoid (-)-maalioxide by the fungus Mucor plumbeus gave three metabolites, 9beta-hydroxymaalioxide, 1beta-hydroxymaalioxide and 7beta-hydroxymaalioxide. 9beta-hydroxymaalioxide and its structure was established on the basis of its spectroscopic properties and chemical reactions.
A new polyisoprenylated benzophenone, guttiferone I, together with the known compounds cambogin, 1,7-dihydroxyxanthone, 1,3,6,7-tetrahydroxyxanthone and 1,3,5,6-tetrahydroxyxanthone were isolated from the stem bark of Garcinia griffithii. The acetone extract of the heartwood of Garcinia mangostana contained one new diprenylated xanthone (mangoxanthone) and a new benzophenone (3',6-dihydroxy-2,4,4'-trimethoxybenzophenone) as well as the known xanthones dulxanthone D, 1,3,7-trihydroxy-2-methoxyxanthone, 1,3,5-trihydroxy-13,13-dimethyl-2H-pyran[7,6-b]xanthen-9-one. Their structures were established on the basis of spectroscopic studies and chemical correlation.
The molecular and electronic structures of 10 free nitroxide radicals have been investigated by HeI/HeII photoelectron spectroscopy (UPS), DFT calculations, and comparison with the spectra of related compounds. We observe that the electronic structure of the nitroxide group is unaffected by substitution except in a carbonyl derivative where nitroxide group orbitals are noticeably stabilized. Also, we have detected small variations in the photoionization cross-sections for singlet and triplet states of cation, the states belonging to the same electron configuration. The relationship between electronic structure and radical reactivity is discussed, and an experimentally based estimate of delocalization energy of the unpaired electron is given. Some conflicting kinetic data on radical reactivity have been analyzed in view of the UPS results.
Two minor metabolites of the whole plant of Bulbophyllum vaginatum collected in Singapore were identified as the biphenanthrene 1 and the phenanthro[4,3-b]furan derivative 2. Structure determinations were performed using a combination of 1D and 2D NMR techniques.
The bark of Garcinia merguensis yielded 10 xanthones, merguenone, 1,5-dihydroxy-6'-methyl-6'-(4-methyl-3-pentenyl)-pyrano(2',3':3,2)-xanthone, subelliptenone H, 8-deoxygartanin, rheediaxanthone A, morusignin G, 6-deoxyjacareubin, 1,3,5-trihydroxy-4,8-di(3-methylbut-2-enyl)-xanthone, rheediachromenoxanthone and 6-deoxyisojacareubin. The structure of merguenone was determined using spectroscopic techniques, mainly 1D and 2D NMR spectroscopy.
Twelve xanthones were isolated from the hexane extract of the heartwood of Garcinia mangostana from Myanmar. Their structures were determined using 1D and 2D NMR techniques