Absolute configuration of macrocyclic spermidine alkaloids

A new macrocyclic spermidine alkaloid from the aerial part of Hyssopus cuspidatus Boriss

Hyssopus cuspidatus Boriss. grows in Xinjiang, China. A new macrocyclic spermidine alkaloid, namely hyssopusizine (1), along with sixteen known compounds were isolated and identified from the aerial parts of H. cuspidatus. Their structures were elucidated on the basis of spectroscopic data and comparison with the literature. Among them, fifteen compounds were isolated from H. cuspidatus for the first time. The absolute configuration of compound 1 was established by comparing the calculated and experimental ECD spectroscopic data. All isolated compounds were tested for their antioxidant and antimicrobial activities. Among them, compound 10 exhibited significant effects on ABTS free-radical scavenging activity with an IC₅₀ value of 15.6 μM. Compounds 5-7 exhibited potent antioxidant activities against ABTS and DPPH. Most compounds exhibited moderate antimicrobial activities. Hyssopusizine (1) is the first macrocyclic spermidine alkaloid discovered from the Hyssopus genus.

Structural and quantitative analysis of Equisetum alkaloids

Equisetum palustre L. is known for its toxicity for livestock. Several studies in the past addressed the isolation and identification of the responsible alkaloids. So far, palustrine (1) and N(5)-formylpalustrine (2) are known alkaloids of E. palustre. A HPLC-ESI-MS/MS method in combination with simple sample work-up was developed to identify and quantitate Equisetum alkaloids. Besides the two known alkaloids six related alkaloids were detected in different Equisetum samples. The structure of the alkaloid palustridiene (3) was derived by comprehensive 1D and 2D NMR experiments. N(5)-Acetylpalustrine (4) was also thoroughly characterized by NMR for the first time. The structure of N(5)-formylpalustridiene (5) is proposed based on mass spectrometry results. Twenty-two E. palustre samples were screened by a HPLC-ESI-MS/MS method after development of a simple sample work-up and in most cases the set of all eight alkaloids were detected in all parts of the plant. A high variability of the alkaloid content and distribution was found depending on plant organ, plant origin and season ranging from 88 to 597mg/kg dried weight. However, palustrine (1) and the alkaloid palustridiene (3) always represented the main alkaloids. For the first time, a comprehensive identification, quantitation and distribution of Equisetum alkaloids was achieved.

Macrocyclic spermidine alkaloids from Androya decaryi L. Perrier

Three new spermidine alkaloids and two known compounds were isolated from the leaves of Androya decaryi. Their structures were elucidated on the basis of their spectroscopic data (NMR and mass spectrometry), by X-Ray diffraction and by comparison with literature values. Evaluation of the in vitro antiplamosdial properties of the isolated compounds revealed they did not possess any significant activity.

Meehanines L-W, spermidine alkaloidal glycosides from Meehania urticifolia

Twelve new spermidine alkaloidal glycosides, meehanines L-W (1-12), were isolated from the whole plant Meehania urticifolia. The structures of these new compounds were elucidated on the basis of spectroscopic data analyses.

Meehanines A-K, spermidine alkaloidal glycosides from Meehania urticifolia

From the whole plant of Meehania urticifolia, 11 new spermidine alkaloidal glycosides, meehanines A-K (1-11), were isolated. The structures of these new compounds were elucidated on the basis of the results of spectroscopic data analysis.

Dracotanosides A-D, spermidine glycosides from Dracocephalum tanguticum: structure and amide rotational barrier

Four new spermidine glycosides, dracotanosides A-D (1-4), have been isolated from Dracocephalum tanguticum. These molecules represent the first spermidine glycosides from this plant genus. The structures, including absolute configurations, were determined by spectroscopic and chemical methods. The amide bond rotational barrier of aglycone 1a was calculated by density functional theory (DFT) computation.

The dihydro-β-agarofuran sesquiterpenoids

Dihydro-Beta-agarofuran sesquiterpenoids are a structurally diverse class of natural products based on tricyclic 5,11-epoxy-5Beta,10alpha-eudesman-4-(14)-ene skeleton. Between January 1990 and June 2006, 462 new dihydro-Beta-agarofuran sesquiterpenoids of 74 structural types have been isolated from about 64 species of Celastraceae, 3 species of Hippocrateaceae and one species of Lamiaceae. The present review covers the chemical and biological activity research of dihydro-Beta-agarofuran sesquiterpenoids in the past 16 years. The chemical research includes structural classification into sesquiterpene polyesters and macrolide sesquiterpene pyridine alkaloids, synthesis of dihydro-Beta-agarofuran as well as extraction, isolation and purification methods. The biological activity research includes activities such as multidrug resistance (MDR) reversal activity, HIV inhibition, cytotoxicity, antitumor activity, antifeedant activity and insecticidal activity with some insights to their modes of actions.

A new class of spermidine-derived alkaloids

[structure: see text] Four new alkaloids, dovyalicins A-D, were isolated from Dovyalis macrocalyx. Their structures were established by two-dimensional COSY, NOESY, HSQC, and HMBC NMR experiments as well as chiroptical methods. The compounds, possessing spermidine as part of a perhydro-1,5-diazocine or a perhydro-1,4-diazepine moiety, constitute a new group of polyamine-derived alkaloids.