Dimethamine — A new bimolecular alkaloid from Thermopsis alterniflora
SummaryFrom the epigeal part ofThermopsis alterniflora, in addition to the alkaloids found previously, argentine, argentamine, and a new alkaloid, dimethamine, which is a representative of the bimolecular series, have been isolated. The structure of 3-(3′,4′-dihydro-N-methylcytisin-5′-yl)-N-methylcytisine has been proposed for dimethamine on the basis of IR, UV, mass, and NMR spectra and also from its conversion products.
Activity of Thermopsis schischkinii Alkaloids Against Influenza A(H1N1)pdm09 Virus
Influenza is an acute viral infection that can easily become a pandemic because of the rate of spread and characteristic high percentage of lethal outcomes [1]. As a rule, chemotherapy agents play a decisive role in such epidemic situations so that the development of effective anti-influenza agents with new mechanisms of antiviral activity remains crucial and has become a worldwide trend for drug discovery in general [2, 3]. Agents of plant origin, including quinolizidine alkaloids, are being extensively examined [4–7]. The goals of the present work were to screen the anti-influenza activity of alkaloids from Thermopsis schischkinii (Fabaceae), which is broadly distributed in the Republic of Bashkortostan (RB), to isolate total alkaloids from the plant, to separate them into fractions, and to identify the pure active compounds. Such an approach was used in research in a similar area [8]. Furthermore, the activity of T. schischkinii alkaloids against influenza A(H1N1) virus has not yet been studied. The aerial part of T. schischkinii that was collected during flowering in the middle of May 2014 under normal conditions for the Sibaisky District of RB was studied. The species was defined by Dr. Biol. Sci. N. I. Fedorov (Ufa Institute of Biology, RAS). A herbarium specimen of T. schischkinii was preserved in the herbarium at IB, USC, RAS (No. 147-2014). Plants were cut 7–10 cm from the base, immediately cut into sections (3–5 cm), and dried in the shade at 20–25°C. Ground air-dried raw material (100 g) was extracted by infusion of aqueous Me2CO (1:9) until a silicotungstic acid test was negative. Total alkaloids were extracted as the free bases using the classical method [9]. Column chromatography used standard silica gel 60 (0.05–0.1 mm, Macherey-Nagel, Germany). GC-MS was recorded using a Thermo Finnigan MAT95XP instrument with electron-impact ionization at 70 eV, injector temperature 250°C, HP-5ms column (30 m 0.25 mm), stationary phase thickness 0.25 m, and temperature regime 120°C (initial, 3 min) and 250°C (isothermal, 10 min). Mixture constituents were identified using total mass spectra and library GC-MS data and the AMDIS (Automated Mass Spectral Deconvolution and Identification System) data processing system [10] and were also confirmed using the reference alkaloids (–)-cytisine, thermopsine, pachycarpine, and anagyrine that were isolated by us earlier [11, 12]. Chromatographic peak areas were normalized internally without using correction factors with the total peak areas of the constituents taken as 100% for quantitative analysis. The yield of all alkaloids isolated from the aerial part of T. schischkinii was 1.6 g (1.6% of the air-dried raw material mass). Six sequential fractions, the alkaloid compositions of which were determined by GC-MS, were obtained after separation of total alkaloids by gradient column chromatography over SiO2 [eluent polarity increasing from CHCl3 to CHCl3–MeOH (7:1), and finally MeOH]. The principal constituents of total alkaloids from T. schischkinii were pachycarpine, (–)-cytisine, thermopsine, anagyrine, N-formylcytisine, and argentamine, the last two of which were observed earlier in T. turcica, T. chinensis, and T. alterniflora [13–17] (Table 1).
The isolation of 11-oxotetrahydrorhombifoline from Ormosia coutinhoi and a study of its mass spectrum
11-Oxotetrahydrorhombifoline (I) has been isolated from the alkaloidal extract of the bark of Ormosia coutinhoi, and its dihydro derivative II has been prepared. An examination of the mass spectra of these compounds and of their 3,3-d2 derivatives has led to the elucidation of the course of the major electron impact induced fragmentations undergone by the molecules. The main fragmentation of I leads to loss of C3H5 from the side chain to form an ion of m/e 221, with a minor path involving a central fission of the molecular ion to form an ion of m/e 150. The mass spectrum of II shows that the loss of C3H7 to form the ion of m/e 221 is a minor process, the main fragmentation reaction involving a central fission to form an ion of m/e 152 analogous to the ion of m/e 150 from I. This change in the spectrum is shown to be consistent with predictions based on the quasi-equilibrium theory of mass spectra.