The present report is a comparative investigation of two Conyza species growing wild in Egypt namely, Conyza dioscoridis (L.) Desf. and Conyza bonariensis (L.) Cronquist. It comprises a genetic and chemical characterization of the plants, as well as an evaluation of their biological activities. The DNA fingerprints of the two species were established based on a polymerase chain reaction (PCR) procedure using ten decamer primers. Further characterization of the plants was performed via determination of pharmacopœial constants, phytochemical screening and estimation of phenolic content (total phenolics, tannins and flavonoids). The ethanol (70%) extracts of C. dioscoridis (EECD) and C. bonariensis (EECB) were subjected to acute toxicity study to determine their LD50; the anti-inflammatory, antimicrobial and cytotoxic activities were then evaluated. Screening for potential cytotoxicity was carried out both by Brine Shrimp Lethality Test and Sulphorodamine-B assay on three human cell lines viz., breast carcinoma (MCF7), colorectal carcinoma (HCT116) and cervical carcinoma (HELA) cell lines. The DNA profiling revealed a similarity index of 88.89% between the investigated species. The variability observed among the pharmacopoeial constants constitute a valuable differential criterion; the total ash, acid insoluble ash, water soluble ash and crude fiber values obtained for C. bonariensis exceeded (17, 5, 10 and 3.5%, respectively) those for C. dioscoridis; meanwhile, the moisture content was higher (10%) in the latter. The phytochemical screening of EECD and EECB revealed the presence of flavonoids, steroids, terpenoids and tannins in both species. Estimation of phenolic contents (total phenolics, tannins and flavonoids expressed as gallic acid, tannic acid and rutin equivalents, respectively) showed that EECD contains higher amounts of all these constituents when compared to EECB (1.17 vs. 0.96 mg/g, total phenolics; 2.43 vs. 1.83 mg/g, tannins and 0.62 vs. 0.29 mg/g, flavonoids). EECD and EECB were found to be safe (LD50 upto 0.5g/kg). Throughout evaluation of the antimicrobial activity against a set of microbial strains and potential cytotoxicity against MCF7, EECD appeared more efficient (MIC: 200-400 µg/ml and IC50: 2.97 μg/ml, respectively); meanwhile, the effect of EECB was more significant on HCT116 and HELA (IC50: 21 and 5.4 μg/ml, respectively). Results of in-vivo assessment of the anti-inflammatory activity showed that the inhibitory effect of EECD was more prominent than that of EECB (74.20% vs. 59.0%). However, the effect of the extracts was inversed in the Brine Shrimp Lethality test (30% vs. 40% lethality, respectively).
Soheir M. El Zalabani, Mona H. Hetta, Ahmed S. Ismail, Genetic Profiling, Chemical Characterization and Biological Evaluation of Two Conyza Species Growing in Egypt. J App Pharm Sci. 2012; 2 (11): 054-061.
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