Proliferative activity of Echinacea angustifolia root extracts on cancer cells: Interference with doxorubicin cytotoxicity.

Doxorubicin is an anticancer drug that causes apoptosis in cells, but cardiotoxicity limits the cumulative dose that can remain in the blood. Echinacea extracts have been prescribed to supplement cancer chemotherapy. In a recent study, it was reported that Echinacea purpurea extracts protected noncancerous cells from apoptosis. Our study aimed to determine interference with doxorubicin chemotherapy, and if fractions and compounds from Echinacea angustifolia roots protected the cells. Cervical and breast cancer cells were treated with the Echinacea samples and doxorubicin. At 0.05 and 0.5 microM doxorubicin concentration, cynarine increased HeLa cell growth by 48-125% and 29-101%, respectively (p<0.01). At 0.05 microM doxorubicin concentration, chicoric acid increased cell growth by 23-100% (p<0.01). When MCF-7 cells were treated with Echinacea and doxorubicin, the ethyl acetate fraction increased cell growth by 20-25%, and chicoric acid increased cell growth by 10-15%. Cynarine showed proliferative activity on HeLa cells, but showed antiproliferative activity on MCF-7 cells. Results indicate that phenolic compounds are responsible for proliferative activity. Studies with individual compounds show that chicoric acid and cynarine interfered with cells treated with 0.5 microM doxorubicin. The results of this study show that Echinacea herbal medicines affect cell proliferation despite cancer treatment, and that herbal medicines require further study with respect to anticancer drugs.

Biocatalysis of the anticancer sipholane triterpenoids.

The Red Sea sponge Callyspongia (= Siphonochalina) siphonella is a rich source of sipholane triterpenoids. Biocatalysis of the major sipholanes, sipholenol A (1) and sipholenone A (2), respectively, by Mucor ramannianus ATCC 9628 and Cunninghamella elegans ATCC 7929 afforded four new metabolites 3 - 6 along with sipholenol G and 28-hydroxysipholenol A. Major sipholanes along with their biocatalytic products were investigated for their antiproliferative activity against the highly malignant +SA mouse mammary epithelial cell line. Sipholenone A (2) was the most active sipholane inhibiting +SA cell proliferation with an IC(50) value of 20 - 30 microM. Sipholenone A, also, showed cytotoxicity against MCF-7 at a dose of 0.9 microM and antiangiogenic activity in the CAM (chorio-allantoic membrane) assay. This is the first report on anticancer activity of these triterpenoids.

Polyoxypregnane glycosides from Caralluma retrospiciens.

Six related polyoxypregnane glycosides were isolated and characterised from Caralluma retrospiciens leaves. The compounds were identified as 12beta-benzoyloxy-8beta,14beta-dihydroxypregn-20-one-3-O-[3-O-methyl-6-deoxy-beta-D-allopyranosyl-(1 --> 4)-beta-D-cymaropyranosyl-(1 --> 4)-]-beta-D-cymaropyranoside], 12beta-benzoyloxy-8beta,14beta-dihydroxypregn-20-one-3-O-[beta-D-glucopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-allopyranosyl-(1 --> 4)-beta-D-cymaropyranosyl-(1 --> 4)-beta-D-cymaropyranoside], 12beta-benzoyloxy-8beta,14beta-dihydroxypregn-20-one-3-O-[beta-D-glucopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-galactopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-galactopyranoside], 12beta-benzoyloxy-8beta,14beta-dihydroxypregn-20-one-3-O-[beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-galactopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-galactopyranoside], 12beta-benzoyloxy-11alpha-isovaleroyloxy-8beta,14beta-dihydroxypregn-20-one-3-O-[beta-D-glucopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-galactopyranosyl-(1 --> 4)-3-O-methyl-6-deoxy-beta-D-galactopyranoside], and 12beta-benzoyloxy-11alpha-isovaleroyloxy-8beta,14beta-dihydroxypregn-20-one-3-O-[beta-D-glucopyranosyl (1 --> 4)-3-O-methyl-6-deoxy-beta-D-allopyranosyl-(1 --> 4)-beta-D-cymaropyranosyl-(1 --> 4)-beta-D-cymaropyranoside]. The structures were determined by detailed analysis of one- and two-dimensional NMR spectra as well as by chemical means. The compounds showed cytotoxic activities towards brine shrimp having IC50 values of 1.19 x 10(-4), 8.83 x 10(-5), 2.64 x 10(-4), 2.26 x 10(-4), 2.39 x 10(-4) and 1.70 x 10(-4) M, respectively. This is the first report of the isolation of these compounds from a natural source.