Isolation and photophysical properties of Di- and Tri-substituted natural anthraquinones from Malaysian Morinda citrifolia

Five di- and tri-substituted natural anthraquinones, i.e. nordamnacanthal (1), damnacanthal (2), rubiadin (3), 1-methoxy-2-methyl-3-hydroxyanthraquinone (4) and 1-hydroxy-3-methoxyanthraquinone (5) were subjected to photophysical studies. The results indicated that steric hindrance and intramolecular hydrogen bonding are important factors that affect absorption and emission spectral of these natural anthraquinones. Besides that, emission properties were significantly enhanced with formation of intramolecular hydrogen bonding in 1,3-dihydroxy-2-aldehyde tri-substituted anthraquinone 1. This gave rise to formation of two additional quasi aromatic rings extending the π-conjugation system in the anthraquinone structure

Fluorescence study of natural anthraquinones and chemical constituents of Boesenbergia stenophylla / Nabila Elyana Adnan

Anthraquinones have significant economic values as dyes and pigments and attracted many interests in advanced studies focusing on optical spectroscopy and photochemistry properties. However, these studies are based on unnatural anthraquinones obtained synthetically. The present dissertation work focused on the fluorescence study of natural anthraquinones isolated from Morinda citrifolia. Ten known anthraquinones obtained from the roots of M. citrifolia have been subjected to the fluorescence study. The effects of substituent groups and intramolecular hydrogen bonding on the fluorescence properties were investigated. The present dissertation work also focused on the phytochemical studies of Boesenbergia stenophylla. B. stenophylla from the family of Zingiberacea, is a perennial rhizomatous herb that can be found in the highland areas of Sarawak, Malaysia. In the present study, two new and two known compounds were isolated from B. stenophylla. All the compounds were isolated and characterized using extensive chromatographic and spectroscopic methods. Several of these compounds were selected for antioxidant assay for their ferric reducing antioxidant power (FRAP)

Isolation and Photophysical Properties of Di- and Tri-substituted Natural Anthraquinones from Malaysian Morinda citrifolia

Five di- and tri-substituted natural anthraquinones, i.e. nordamnacanthal (1), damnacanthal (2), rubiadin (3), 1-methoxy-2-methyl-3-hydroxyanthraquinone (4) and 1-hydroxy-3-methoxyanthraquinone (5) were subjected to photophysical studies. The results indicated that steric hindrance and intramolecular hydrogen bonding are important factors that affect absorption and emission spectral of these natural anthraquinones. Besides that, emission properties were significantly enhanced with formation of intramolecular hydrogen bonding in 1,3-dihydroxy-2-aldehyde tri-substituted anthraquinone 1. This gave rise to formation of two additional quasi aromatic rings extending the π-conjugation system in the anthraquinone structure

Chemical constituents and anti-neuroblastoma activity from Boesenbergia stenophylla

Three diarylheptanoids and one flavonoid, i.e. 7-(4-hydroxy-3-methoxyphenyl)-1-phenylhept-4-en-3-one (4), 5R-hydroxy-7-(4-hydroxy-3-methoxyphenyl)-1-phenylheptan-3-one (5), 1,7-diphenylhept-4-en-3-one (6), and 3,5,7-trihydroxyflavone (7) were isolated and characterized from the rhizome of Boesenbergia stenophylla. Compounds 2 and 4 displayed excellent anti-neuroblastoma activity which reduces the cell viability to 30% and 20%, respectively. The results from the molecular docking experiments targeting the protein kinases regulating neuroblastoma cell survival (PI3K/AKT1 signalling pathway) are consistent with that of the in vitro results. Finally, the structures of 4-7 were elucidated using spectroscopic methods (UV, IR, NMR, and HRESIMS)