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A new caffeate derivative from the ethanol extract of the stem bark of Cassia sieberiana DC. is described herein along with the known secondary metabolites spectaline ( 2 ), iso -6-cassine ( 3 ), 3- O -methyl- chiro -inositol ( 4 ), monobehenin ( 5 ), octyl nonadecyloate ( 6 ), β -sitosterol ( 7 ), stigmasterol ( 8 ) and sitosterol 3- O - β -D-glucopyranoside ( 9 ). The chemical structures were elucidated by means of various spectroscopic and spectrometric techniques. Extract and isolated compounds were devoid of inhibitory action against the herein selected bacterial strains (MICs > 256 μg/mL) but showed capacities to reduce 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (EC 50  < 3 μg/mL) considerably better than the "gold standard" trolox (EC 50 6.47 ± 0.48 μg/mL).

Background: The proliferation and resistance of microorganisms area serious threat against humankind and the search for new therapeutics is needed. The present report describes the antiplasmodial and anticancer activities of samples isolated from the methanol extract of Albizia zygia (Mimosaseae)., Material: The plant extract was prepared by maceration in methanol. Standard chromatographic, HPLC and spectroscopic methods were used to isolate and identify six compounds (1-6). The acetylated derivatives (7-10) were prepared by modifying 2-O-β-D-glucopyranosyl-4-hydroxyphenylacetic acid and quercetin 3-O-α-L-rhamnopyranoside, previously isolated from A. zygia (Mimosaceae). A two-fold serial micro-dilution method was used to determine the IC 50s against five tumor cell lines and Plasmodium falciparum., Results: In general, compounds showed moderate activity against the human pancreatic carcinoma cell line MiaPaca-2 (10 < IC 50 < 20 μM) and weak activity against other tumor cell lines such as lung (A-549), hepatocarcinoma (HepG2) and human breast adenocarcinoma (MCF-7and A2058) (IC 50 > 20 μM). Additionally, the two semi-synthetic derivatives of quercetin 3-O-α-L-rhamnopyranoside exhibited significant activity against P. falciparum with IC 50 of 7.47 ± 0.25 μM for compound 9 and 6.77 ± 0.25 μM for compound 10, higher than that of their natural precursor (IC 50 25.1 ± 0.25 μM)., Conclusion: The results of this study clearly suggest that, the appropriate introduction of acetyl groups into some flavonoids could lead to more useful derivatives for the development of an antiplasmodial agent.