Phytochemical and Cytotoxic Studies of Rumex pictus Forssk. and Rumex vesicarius L. (Family Polygonaceae), Growing in Egypt

Aims: Rumex pictus Forssk. and Rumex vesicarius L., Family Polygonaceae, wildly growing in Egypt possess many biological activities. The current study was performed to study the phytochemical constituents and the in vitro cytotoxic activity of the successive extracts of the aerial parts of Rumex pictus and Rumex vesicarius.

Place and Duration of Study: Department of Pharmacognosy, National Research Centre, Giza, Egypt, between March 2014 and January 2015.

Methodology: The preliminary phytochemical screening of the aerial parts of Rumex pictus and Rumex vesicarius, revealed the presence of volatiles, phenolic compounds, sterols, terpenes and carbohydrates in both species. The volatile constituents were prepared from the fresh aerial parts of each of the plants by hydro-distillation and their chemical composition was identified using GC and GC/MS. The results revealed the presence of hexahydrofarnesyl acetone (7.29%) and o-xylene (5.63%) as the major components in R. pictus and R. vesicarius, respectively. The lipoidal content of the aerial parts of each species was prepared and analyzed after saponification by GC/MS. The results revealed the presence of unsaturated fatty acids as oleic (6.54%) in R. pictus and ricinoleic (13.7%) in R. vesicarius. Sterols including campesterol, stigmasterol, β-sitosterol, α- and β-amyrin were present in both species while taraxasterol was detected only in R. pictus. The amino acid content of each of the species was analyzed and the results revealed the presence of phenylalanine, threonine, valine, methionine, isoleucine, leucine, histidine and lysine as essential amino acids in both species at different proportions. The study of carbohydrates revealed the presence of the free sugars glucose, fructose, sucrose and mannitol in both species with different percentages, while the polysaccharide content was prepared and analyzed qualitatively and quantitatively after hydrolysis by GC and GC/MS. Glucose, rhamnose, arabinose, galactose and ribose were detected in both species, while sorbitol was present in R. pictus only. The different successive extracts of the aerial parts of the two species were tested for their cytotoxic activity on breast cancer (MCF-7), lung carcinoma (A549) and hepatocellular carcinoma (HepG2) cell lines. The results revealed that the chloroformic extract of the aerial parts of R. pictus showed significant cytotoxic activity against hepatocellular carcinoma (HepG2) cell line (IC50= 1.33 μg/mL) and lung carcinoma (A549) (IC50= 3.35 μg/mL) cell line when compared to Doxorubicin, while, the 70% methanolic extract of the aerial parts of R. pictus showed significant cytotoxic activity towards breast cancer (MCF7) cell line (IC50= 15.5 μg/mL). This is the first report of the cytotoxic activity of R. pictus.

Conclusion: In conclusion, the preliminary phytochemical screening of the aerial parts of R. pictus and R. vesicarius (Family Polygonaceae) revealed the presence of a variety of constituents including volatile compounds, carbohydrates and /or glycosides, flavonoids, anthraquinones, sterols and/or terpenes, tannins and amino acids, as well as, significant cytotoxic activity of the different successive extracts with variable proportions.