Chemical and biological studies on Tamarix nilotica growing in Egypt

Tamarix nilotica (Ehrenb.) Bunge (Tamaricaceae) has been used since Pharaonic times to expel fever, relieve headache, draw out inflammation and as an aphrodisiac agent. In vitro antioxidant activity of extracts prepared from the leaves and flowers of T. nilotica was tested. Three in vitro antioxidant assays were used: 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, superoxide anion scavenging activity and iron chelating activity. Both extracts showed significant in vitro antioxidant activity. The hydro-alcoholic extract (80%) of T. nilotica flowers was evaluated for in vivo hepatoprotective and antioxidant activities. Hepatoprotective activity was assessed using carbon tetrachloride-induced hepatic injury in rats by monitoring biochemical parameters such as serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase and alkaline phosphatase. Antioxidant activity was evaluated in alloxan-induced diabetic rats. The hydro-alcoholic extract of T. nilotica flowers (100 mg/kg body weight) ameliorated the adverse effects of carbon tetrachloride and returned the altered levels of biochemical markers near to the normal levels. Phytochemical investigation of the leaves of T. nilotica has led to isolation of methyl ferulate 3-O-sulphate for the first time from natural sources. Coniferyl alcohol 4-O-sulphate, kaempferol 4′-methyl ether, tamarixetin and quercetin 3-O-β-D-glucupyranuronide were isolated from the n-butanol soluble fraction of the extract. The pentacyclic triterpenoid, 3α-(3″,4″-dihydroxy-trans-cinnamoyloxy)-D-friedoolean-14-en-28-oic acid was isolated from the n-hexane soluble fraction of the extract. The structures of these compounds were determined on the basis of spectroscopic analyses. The isolated triterpene showed the highest DPPH radical scavenging activity with IC₅₀ 21.2µM.

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