Chemical Constituents Of Mitrella Kentii ( Annonaceae ) Ainnul Hamidah
Abstract: Mitrella kentii which belongs to the Annonaceae family is a tree-climbing liana found in the Malaysian Peninsula, Islands of Sumatra, Borneo, and New Guinea. This species was studied in 1972 for their alkaloids, 1997 and 2012 for their non-alkaloid constituents. In this study, chalcones, Desmosdumotin C (1) and their tautomer, 2-cinnamoyl3-hydroxy-5-methoxy-4,6,6-trimethylcyclohexa-2,4-dienone (2), flavanone, 7-hydroxy-5,6-dimethoxy-2-phenylchroman4-one (3), oxoaporphine alkaloids, Liriodenine (4) and Atherospermidine (5) and also terpenoid, -Sitostenone (6) have been isolated from this species. All these compounds were isolated for the first time from Mitrella kentii except Liriodenine (4). The isolated compounds were elucidated using spectroscopic techniques such as UV, IR,1D and 2D NMR and mass spectroscopy and by comparison their spectral data with those previously reported in the literatures. Desmosdumotin C (1) showed the anti-ulcer activity.
The alkaloids of Mitrella kentii (Annonaceae)
Mitrella kentii (Bl.) Rliq. of the family Annonaceae is a tree-climbing liana, found in the oak-forests of New Guinea. The alkaloidal constituents of this species have not previously been examined though field tests1 indicated their presence in the bark. Thin-layer chromatograms of the crude alkaloid mixture (yield: 0.063% of dry weight) resembled those originating from Scheffe~oomita subaequalis,2 another New Guinean liana of the same plant family. In fact all four alkaloids isolated were also present in S, subaequalis. The three main constituents were identified as liriodenine, anonaine, and asimilobine by direct comparison with authentic specimens. The fourth, minor, alkaloid was shown to be identical with aequaline.
Development of new analytical methods for the determination of caffeine content in aqueous solution of green coffee beans
BackgroundThis study was conducted to develop fast and cost effective methods for the determination of caffeine in green coffee beans. In the present work direct determination of caffeine in aqueous solution of green coffee bean was performed using FT-IR-ATR and fluorescence spectrophotometry. Caffeine was also directly determined in dimethylformamide solution using NIR spectroscopy with univariate calibration technique.ResultsThe percentage of caffeine for the same sample of green coffee beans was determined using the three newly developed methods. The caffeine content of the green coffee beans was found to be 1.52 ± 0.09 (% w/w) using FT-IR-ATR, 1.50 ± 0.14 (% w/w) using NIR and 1.50 ± 0.05 (% w/w) using fluorescence spectroscopy. The means of the three methods were compared by applying one way analysis of variance and at p = 0.05 significance level the means were not significantly different. The percentage of caffeine in the same sample of green coffee bean was also determined by using the literature reported UV/Vis spectrophotometric method for comparison and found to be 1.40 ± 0.02 (% w/w).ConclusionNew simple, rapid and inexpensive methods were developed for direct determination of caffeine content in aqueous solution of green coffee beans using FT-IR-ATR and fluorescence spectrophotometries. NIR spectrophotometry can also be used as alternative choice of caffeine determination using reduced amount of organic solvent (dimethylformamide) and univariate calibration technique. These analytical methods may therefore, be recommended for the rapid, simple, safe and cost effective determination of caffeine in green coffee beans.