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 constituents and hepatoprotective activity of Viburnum tinus.

From the leaves of Viburnum tinus L. (Adoxaceae) two acylated iridoid glucosides (viburtinoside A and B), a coumarin diglucoside scopoletin 7-O-beta-D-sophoroside and a natural occurred dinicotinic acid ester 2,6-di-C-methyl-nicotinic acid 3,5-diethyl ester were isolated. In addition to these, 10 known compounds were isolated, namely two bidesmosidic saponins, a hexamethoxy-flavone and five flavonol glycosides, as well as suspensolide A and oleanolic acid were isolated for the first time in this genus and species, respectively. The structures were determined mainly by spectroscopic methods (UV, IR, ESI-MS, 1H-, 13C NMR and DEPT). Toxicity of the investigated extract was determined (LD50=500 mg/kg). CCl4-induced hepatotoxicity has been evaluated in terms of the determination of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lipid peroxide and nitric oxide levels in serum and compared using adult male rats weighing 150-180 g. Their highly elevated levels were significantly reduced by treatment with the investigated aqueous methanol extract in dose-dependent manner.

Cytotoxic activity of Vitex trifolia purpurea extracts.

Defatted 85% crude hot aqueous methanol extract of Vitex trifolia purpurea (AME) successively extracted with, chloroform and ethyl acetate. Cytotoxicity of (AME), chloroform methanol extract (CE), ethyl acetate methanol extract (EE) and the residue obtained from methanol extract after successive extraction (RME) have been evaluated on brine shrimp (Artemia salina) and Hep-G2 cell lines as well. In brine shrimp lethality bioassay the results revealed that the (RME) is the most potent one with LC50 value 173 microg/ml while LC50 values of (AME), (CE) and (EE) was 180, 199 and 286 microg/ml, respectively. As well as the results of cytotoxic assay against Hep-G2 cell lines are in full agreement with previous results, with IC50 values 6, 10.7, 20.8 and 65.8 microg/ml for (RME), (AME), (CE) and (EE), 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.