No abstract

No abstract

Syntheses of unusual pyrrole alkaloids Penicinoline E, Marinamide and Methyl marinamide were successfully achieved in two steps from easily accessible starting materials with excellent overall yields 70–97 %. The Suzuki‐Miyaura coupling followed by dearomatization represents the key step in the synthesis of title compounds. The structure of Penicinoline E was unequivocally confirmed by single X‐ray analysis. The antiplasmodial activity of alkaloids was evaluated and shown a good antimalarial activity against human malaria parasite Plasmodium falciparum in vitro. Against chloroquine sensitive (pf3d7), both Penicinoline E and Methyl marinamide displayed IC50 value of 1.56 μM and Marinamide displayed IC50 value of 25 μM respectively. In addition, against chloroquine resistant strain (pfDd2) of plasmodium falciparum they have also shown 4.68 μM, 2.34 μM and 25 μM respectively.

Novel thiazolyl hydrazonothiazolamines and 1,3,4‐thiadiazinyl hydrazonothiazolamines were synthesized by a facile one‐pot multicomponent approach by the reaction of 2‐amino‐4‐methyl‐5‐acetylthiazole, thiosemicarbazide or thiocarbohydrazide and phenacyl bromides or 3‐(2‐bromoacetyl)‐2H‐chromen‐2‐ones in acetic acid with good to excellent yields. These new compounds were screened in vitro for their antimalarial activity; among them, four compounds, 4h, 4i, 4k, 4l, showed moderate activity with half‐maximal inhibitory concentration (IC50) values of 3.2, 2.7, 2.7, and 2.8 and 3.2, 3.2, 3.1, and 3.5 μM against chloroquine‐sensitive and ‐resistant strains of Plasmodium falciparum, respectively. Compound 4l inhibited the ring stage growth of P. falciparum 3D7 at an IC90 concentration of 12.5 µM in a stage‐specific assay method, where the culture is incubated with specific stages of P. falciparum for 12 hr, and no activity was found against the trophozoite and schizont stages, confirming that 4l may have potent action against the ring stage of P. falciparum.

No abstract