Antioxidant and cytotoxic activity of polyphenolic compounds isolated from the leaves of Leucenia leucocephala.

CONTEXT: Cancer is a serious clinical problem to the health care system. Anticancer drugs have been extracted from plants containing phenolic compounds. Leucenia species (Fabaceae) contain a variety of bioactive components of numerous biological and pharmacological properties. OBJECTIVE: This study explored the constitutive polyphenols of Leucenia leucocephala Lam. growing in Egypt and evaluated the antioxidant and cytotoxic activity. MATERIALS AND METHODS: Chemical structures of the isolated compounds from the leaves of L. leucocephala were established by spectral techniques (UV, (1)H, and (13)C NMR, MS). RESULTS: Chromatographic separation of 80% MeOH extract of the leaves of L. leucocephala have resulted in a novel flavonoid-galloyl glycoside [myricetin 3-O-(2',3'4'-tri-O-galloyl)-α-L-rhamnopyranoside] with three known polyphenolic compounds isolated for the first time from this species (apigenin 7-O-ß-D-glucuronopyranoside methyl ester, luteolin 7-O-ß-D-glucuronopyranoside methyl ester, and 1,3,6-tri-O-galloyl-ß-D-glucopyranose) and seven known previously isolated compounds. Also, 80% methanol extract exhibited high antioxidant activity (SC(50) = 3.94 µg/ml), which is correlated with its phenolic content. The extract also showed cytotoxic activity against Hep G2 (IC(50) value 1.41 µg/ml) confirming its anticancer activity against hepatocellular carcinoma. Among the tested compounds (4-8) for antioxidant property, compound 7 was the most active compound (SC(50) = 2.49 µg/ml). Also compounds 7 and 8 exhibited high cytotoxic activity (IC(50) = 2.41 and 2.81 µg/ml, respectively). DISCUSSION AND CONCLUSION: 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.

Non-phenolic antioxidant compounds from Buddleja asiatica.

The methanol extract of the leaves of Buddleja asiatica Lour. (Loganiaceae) showed antioxidant activity toward the well known in vitro antioxidant tests such as total antioxidant capacity by the phosphomolybdenum method, free radical scavenging activity by the 1,1-diphenyl-2-picrylhydrazyl scavenging assay (DPPH assay) and hydrogen peroxide scavenging methods. Due to the high scavenging activity of the n-butanol successive fraction toward DPPH and H2O2 (SC50 = 11.99 and 18.54 microg/ml, respectively), this extract was subjected to chromatographic separation and isolation. Four non-phenolic compounds were isolated and identified on the basis of spectroscopic and chemical analyses: 1-O-beta-D-glucopyranosyl-2-methoxy-3-(2-hydroxy-triaconta-3,12-dienoate)-glycerol (1), 3-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->3)]-[beta-D-glucopyranosyl-(1-->2)]-beta-D-fucopyranosyl-olean-11,13(18)-diene-3 beta,23,28-triol (2), 3-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->3)]-beta-D-fucopyranosyl-olean-11,13(18)-diene-3,23,28-triol (3), and 3-O-[alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->3)]-[beta-D-xylopyranosyl-(1-->2)]-beta-D-glucuronopyranosyl-acid-olean-11,13(18)-diene-3 beta,23,28-triol (4). The four compounds were evaluated as antioxidant agents using the three antioxidant bioassay tests.

Phytochemical and molluscicidal investigations of Fagonia arabica.

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-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranoside oleanolic acid (1), 3-O-alpha-L-arabinopyranosyl quinovic acid 28-O-beta-D-glucopyranoside (2), 3-O-[beta-D-glucopyranosyl-(1-->2)]-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinosyl oleanolic acid (3) and 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabino-pyranosyl quinovic acid 28-O-beta-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 microM), whereas the other two bidesmosidic saponins 2 and 4 as well as the two flavonoid glycosides were inactive up to 50 microM.

Cytotoxic cholestane and pregnane glycosides from Tribulus macropterus.

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) (IC50 = 2.9 microg/ml). The n-butanolic fraction obtained from successive fractionation of the methanolic extract exhibited activity against HepG2 (IC50 = 2.6 microg/ml). Therefore, this fraction was subjected to separation using different chromatographic techniques. Five compounds, 1-5, were isolated and identified as: (22S,25S)-16beta,22,26-trihydroxy-cholest-4-en-3-one-16-O-beta-D-glucopyranosyl-(1-->3)-beta-D-xylopyranoside (1), (22S,25S)-16beta,22,26-trihydroxy-cholest-4-en-3-one-16-O-beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranoside (2), sucrose (3), D-pinitol (4) and 3beta-hydroxy-5a-pregn-16(17)en-20-one-3-O-beta-D-xylopyranosyl-(1-->2)-[beta-D-xylopyranosyl-(1-->3)]-beta-D-glucopyranosyl-(1-->4)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-ga-lactopyranoside (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 IC50 values were 2.4, 2.2 and 1.1 microg/ml, respectively.

Effect of Ficus sycomorus and Azadirachta indica extracts on liver state of mice infected with Schistosoma mansoni.

The potential role of hepatoprotective and antipathological effect of Ficus sycomorus and Azadirachta indica extracts was evaluated for scavenging the reactive oxygen species (ROS) and reduced the oxidative damage and pathological changes in the liver of S. mansoni infected mice. The levels of alanine aminotransferase (ALT), asparate aminotransferase (AST) and gamma glutamyl transferase (GGT) were evaluated in the infected mice and treated orally with each plant extract 12 weeks post infection (P.I.) in a dose of 500 mg/kg of each plant extract for five consecutive days and sacrificed two weeks P.I. The infection of mice showed an elevation of ALT, AST & GGT. Treatment of mice with 70% methanol extract of each plant extract reduced significantly ALT, AST & GGT elevation. The highest reduction was with the methanolic extract of F. sycomorus (42%, 35% &44% for ALT, AST & GGT respectively). Fractionation of the methanolic extract of each plant was carried out. The effect of ethyl acetate and butanolic fractions of each plant was also evaluated. The result showed that the two fractions lowered the levels of the tested enzymes and decreased the number and size of granuloma diameters with an increased in the percentage of degenerated ova.