Two new resin glycosides, ipomeolides
A (1) and B
(2), both with an unusual nonlinear heteropentasaccharide
core, along with five known compounds were isolated from the n-hexane/CHCl3 (1:1) extract of the aerial parts
of Ipomoea pes-caprae. Ipomeolides A (1) and B (2) are macrolactone analogues of the rare (11R)-jalapinolic acid, and macrolactonization occurred at
C-2 of the second saccharide moiety. Compounds 1 and 2 show structural variation even in the pentasaccharide core.
The structures of 1 and 2 were established
by a combination of spectroscopic techniques as well as chemical modifications
such as acetyl and acetonide derivatives as well as hydrolysis products.
The new glycosidic acid was named ipomeic acid (1c).
Compounds 1, 1b, and 2b were
evaluated for cytotoxicity against human tumor cell lines. Compounds 1b and 2b were not effective on epithelial cells,
but affected survival of K-562, which is of hematopoietic origin.
A sublethal concentration of compound 1 (4 μM)
when used in combination with 1 μM doxorubicin, an anticancer
agent, significantly enhanced cytotoxicity to tumor cells. Such combined
synergistic potency against leukemia cells and the absence of effects
on epithelial cells may be beneficial for chemotherapy with minimal
side effects to treat CML (chronic myeloid leukemia) malignancies.
The biotransformation of the front-line antimalarial drug, artemisinin (1) by the filamentous fungus Aspergillus flavus MTCC-9167 was investigated. Incubation of compound 1 with A. flavus afforded a new hydroxy derivative (2) along with three known metabolites (3-5). The new compound was characterized as 14-hydroxydeoxyartemisinin (2) by extensive spectroscopic data analysis (IR, H andC NMR, HSQC, HMBC, COSY, NOESY, and HR-ESIMS). The known metabolites were identified as deoxyartemisinin (3), artemisinin G (4), and 4α-hydroxydeoxyartemisinin (5). This is the first report of hydroxylation of a secondary methyl of artemisinin at C-14 by the fungus A. flavus, which is synthetically not accessible. In addition, these compounds were evaluated for their in vitro antiplasmodial activity. Artemisinin G (4) exhibited IC values in the submicromolar range, which was better than those of the nonperoxidic metabolites.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.