The present study was designed to identify the chemical constituents of the methanolic extract of Curcuma longa L. rhizomes and their inhibitory effect on a hepatoma cell line. The methanolic extract was subjected to GC-MS analysis to identify the volatile constituents and the other part of the same extract was subjected to liquid column chromatographic separation to isolate curcumin. The inhibition of cell growth in the hepatoma cell line and the cytopathological changes were studied. GC-MS analysis showed the presence of fifty compounds in the methanolic extract of C. longa. The major compounds were ar-turmerone (20.50 %), β-sesquiphellandrene (5.20 %) and curcumenol (5.11 %). Curcumin was identified using IR, 1H and 13C NMR. The inhibition of cell growth by curcumin (IC50 = 41.69 ± 2.87 μg mL-1) was much more effective than that of methanolic extract (IC50 = 196.12 ± 5.25 μg mL-1). Degenerative and apoptotic changes were more evident in curcumin- treated hepatoma cells than in those treated with the methanol extract. Antitumor potential of the methanolic extract may be attributed to the presence of sesquiterpenes and phenolic constituents including curcumin (0.051 %, 511.39 μg g-1 dried methanol extract) in C. longa rhizomes.

These findings demonstrate that the leaves of L. leucocephala contain a considerable amount of polyphenolic compounds with high antioxidant properties, thus it has great potential as a source for natural health products.

The aqueous methanolic extract of the aerial parts of Fagonia arabica L. (family Zygophyllaceae) was successively fractionated using certain organic solvents. From the ethyl acetate fraction, two flavonoid glycosides were isolated and identified as kaempferol-7-O-rhamnoside and acacetin-7-O-rhamnoside. Four triterpenoidal glycosides were isolated from the butanolic layer. Their structures were elucidated on the basis of the spectral and chemical data as 3-O-β-D-glucopyranosyl-(1→3)-α-L-arabinopyranoside oleanolic acid (1), 3-O-α-L-arabinopyranosyl quinovic acid 28-O-β-D-glucopyranoside (2), 3-O-β-D-glucopyranosyl- (1→2)]-β-D-glucopyranosyl-(1→3)-α-L-arabinosyl oleanolic acid (3) and 3-O-β-D-glucopyranosyl-( 1→3)-α-L-arabino-pyranosyl quinovic acid 28-O-β-D-glucopyranoside (4). The two monodesmosidic saponins 1 and 3 were found to possess strong molluscicidal activity against Biomphalaria alexandrina snails, the intermediate host of Schistosoma mansoni in Egypt (LC90 = 13.33 and 16.44 μM), whereas the other two bidesmosidic saponins 2 and 4 as well as the two flavonoid glycosides were inactive up to 50 μM.

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The methanol extract of the whole parts of Tribulus macropterus Boiss. (family Zygophyllaceae) showed cytotoxic activity against a human tumour cell line (hepatocyte generation 2, HepG2) (IC 50 = 2.9 μg/ml). The n-butanolic fraction obtained from successive fractionation of the methanolic extract exhibited activity against HepG2 (IC 50 = 2.6 μg/ml). Therefore, this fraction was subjected to separation using different chromatographic techniques. Five compounds, 1Ð5, were isolated and identified as: (22S,25S)-16 ,22,26-trihydroxy-cholest-4-en-3-one-16-O--d-glucopyranosyl-(153)--d-xylopyranoside (1), (22S,25S)-16 ,22,26-trihydroxy-cholest-4-en-3-one-16-O--d-glucopyranosyl-(153)--d-glucopyranoside (2), sucrose (3), d-pinitol (4) and 3 -hydroxy-5α-pregn-16(17)en-20-one-3-O--d-xylopyranosyl-(152)-[ -d-xylopyranosyl-(153)]--d-glucopyranosyl-(154)-[α-l-rhamnopyranosyl-(152)]--d-galactopyranoside (5) on the basis of spectroscopic and chemical data. The three steroidal compounds 1, 2 and 5 were also tested against the same cell line HepG2 and their IC 50 values were 2.4, 2.2 and 1.1 μg/ml, respectively.