Chemical Constituents from the Whole Plant of Cuscuta reflexa

Two new 2H-pyran-2-one glucosides, cuscutarosides A (1) and B (2), and one new steroidal glucoside, 7β-methoxy-β-sitosterol 3-O-β-glucopyranoside (3), together with 12 known compounds (4–15) were isolated from the whole plant of Cuscuta reflexa (Convolvulaceae) collected from Myanmar. The chemical structures of these new compounds were elucidated based on extensive spectroscopic analysis. The antiobesity activity of these isolates was evaluated using porcine pancreatic lipase (PPL), and the antiplatelet aggregation activity was screened using rabbit platelets induced by thrombin, platelet-activating factor (PAF), arachidonate (AA), or collagen. 7β-Methoxy-β-sitosterol 3-O-β-glucopyranoside (3) showed weak PPL inhibitory activity. Cuscutaroside A (1), its acetylated derivative (1a), and scrophenoside B (8) showed weak inhibitory activity against rabbit platelet aggregation induced by collagen. Compound 1a also showed inhibitory activity against rabbit platelet aggregation induced by AA. Graphic Abstract

Structurally Diverse Metal Coordination Compounds, Bearing Imidodiphosphinate and Diphosphinoamine Ligands, as Potential Inhibitors of the Platelet Activating Factor

Metal complexes bearing dichalcogenated imidodiphosphinate[R2P(E)NP(E)R2′]-ligands (E = O, S, Se, Te), which act as (E,E) chelates, exhibit a remarkable variety of three-dimensional structures. A series of such complexes, namely, square-planar[Cu{(OPPh2)(OPPh2)N-O,O}2], tetrahedral[Zn{(EPPh2)(EPPh2)N-E,E}2], E = O, S, and octahedral[Ga{(OPPh2)(OPPh2)N-O,O}3], were tested as potential inhibitors of either the platelet activating factor (PAF)- or thrombin-induced aggregation in both washed rabbit platelets and rabbit platelet rich plasma. For comparison, square-planar[Ni{(Ph2P)2N-S-CHMePh-P,P}X2], X = Cl, Br, the corresponding metal salts of all complexes and the(OPPh2)(OPPh2)NHligand were also investigated.Ga(O,O)3showed the highest anti-PAF activity but did not inhibit the thrombin-related pathway, whereasZn(S,S)2, with also a significant PAF inhibitory effect, exhibited the highest thrombin-related inhibition.Zn(O,O)2andCu(O,O)2inhibited moderately both PAF and thrombin, being more effective towards PAF. This work shows that the PAF-inhibitory action depends on the structure of the complexes studied, with the bulkierGa(O,O)3being the most efficient and selective inhibitor.