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-Lrhamnopyranoside, previously isolated from A. zygia (Mimosaceae). A twofold 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.

The phytochemical study of the ethanol extract from Crinum distichum Herb. was carried out using reversed phase high performance liquid chromatography and afforded a new natural flavan (1), along with (2S)-4'-hydroxy-7-methoxyflavan (2), (2R)-4´-hydroxy-5,7-dimethoxyflavan (3), hippadine (4) and hippacine(5). The structure of the new compound was elucidated using a combination of NMR and HRESI-MS analysis while the structures of the known compounds were established by comparison of their spectroscopic data with those of similar reported compounds. Compounds 2-5 also had moderate activity (32> MIC> 16 µg/mL) against methicillin resistant (MRSA) and methicillin sensitive (MSSA) Staphylococcus aureus (both Gram-positive bacteria), whilst compound 1 was inactive against these two bacterial strains (MIC>128µg/mL). None of the compounds was active against the Gram-negative bacterial strains Escherichia coli and Klesbesiella pneumoniae. The research described herein confirms once more that, plants of the Crinum genus continue to be a rich and underexploited source of new small molecules that could lead to the discovery of new bioactive compounds.

Rothmannia talbotii, a hitherto chemically unexplored medicinal plant, is used in the Western Region of Cameroon to relieve fever. In our ongoing search for bioactive compounds from Cameroonian medicinal plants, a previously undescribed compound rothtalazepane (1), along with six known compounds, aitchisonide B (2), D-mannitol (3), β-D-glucopyranosyl-(6→1’)-β-D-glucopyranoside (4), monopalmitin (5), stigmasterol (6), and sitosterol 3- O-β-D-glucopyranoside (7) were isolated and characterized from the crude ethanol extract of the wood of R. talbotii. Rothtalazepane (1) exhibits no significant activity against several microbial strains, thus its function likely lies not in antimicrobial defense and it is not the active principle against urinary infections described for Rothmannia.