A Comparative Study of Antioxidants Activities and Heavy Metals Content of some Medicinal Plants in Sudan

Abstract

Samples of Five different plants(Psidium guajava (Aljawafa),Schoenanthus cymbopogone (Almharib) , Solenostemma argel(Alhargil), Hyphaene thebaica (Aldoum) and Petroselinum crispum (Albagdunas) used in many parts of Sudan as herbal medicine. The plant samples were collected randomly from different locations of sudan.The aim of study is to evaluate the phytochemicals components of plants and their potentiality as a source of biologically activecompounds , in addition determination of heavy metals content. Four different solvents of varying polarities were used for preparation the crude extract from the plant samples.The dried plants materials were subjected to successive extraction with petroleum ether, then ethyl acetate , acetoneand finally with ethanol .The results clearly indicated variation of the total yields , theP.guajava extract gave the highest yield (7.001%) followed by S. argel(6.551%),P. Crispum (4.760%),S. Cymbopogone (4.633%) andH. thebaica (2.538%).Antioxidant activityand free radical moietiesanalysedby two reagents 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) and 2.2. azinobisethylbenzoline-4- sulfonic acid (ATBS) using spectrophotometricmeasurement. In the DPPH assaypetroleum ether extract revealed a non-significant free radical scavenging activity, with scavenging activity ranging between 0.16% for P.crispum , 29% for P.guajava and 30% for S.cymbopogon extracts while S.argel and H.thebaica extracts showed no antioxidants effect,P. guajava sample exhibited high activity with scavenging rate (90%, 89.2% and 89%) with ethanol, acetone and ethylacetateextracts respectively.ABTS radical exhibited good antioxidant activities compared with DPPH free radicals.The highest scavenging ability was exhibited by ethanol extract fromP.guajava(94%), while the lowest was determined in the acetone extract of P.crispum (69%).Analysis for heavy metals ,results showed the range (0.037 -0.166 ppm)for Zn, (0.024 -0.2 ppm)for Mn, (103.15 -198.3 ppm)for Fe, (0.001 -0.004 ppm)for Cd , (0.012 -0.099 ppm)for III Co,and (37 -79 ppm)forNi , using atomic absorption spectroscopyand showed that the levelswere in the permissible limits according to World Health Organization (WHO), lead less than detection limit in all samples.Percentages of plants components revealed the amount of moisture(94.1 -94.9), protein(1.4 -10.2), fibre(8.7 -26.5) and ash(4.9 -7.1). The quantitative spectrophotometric analysis indicated that all plant extracts contained amount of plant samples polyphenols (0.103,0.155,0.270,0.314and0.374 mg/ml) forP.Crispum, S. cymbopogone, S. argel ,P. Guajava and H. thebaica,flavonoids results ranging between(0.21 -0.55mg/ml) to S. argelandS. cymbopogone respectively, amount of alkaloids ranging (0.025mg/ml forP. Guajava to 0.101mg/ml for S.argel)and tannins showed (0.23mg/ml forS.argel to 0.56mg/ml forP.Crispum).Gaschromatography (GC) was used to determineSaturated and unsaturated fatty acids in all plant extracts. Results showed various kinds of fatty acids ,Cis-10-Heptadecenoic acid methyl ester ranging between(41.99 -70.41%) which was the dominant fatty acid followed by Cis-11-Eicosenoic acid methyl ester(3.25 -11.82%) and pentadecenoic acid methyl ester(4.39 -15.84%) they are prevailing fatty acids. Reliable methods were adopted for testing the bioactivity of the components towards four bacterial species (Bacillus subtilis Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus), the obtained results of solvents extract withbacterial strainshowed B.s(12.5 -20mm),E.c (11 -23mm),P.a (11 -23.5 mm) and S.a (13 -21 mm) and two fungal species A. Niger(0 -23 mm) and C. Albicans(0 -21mm). All plant extracts were non-toxic towards the normal cell line (IC50 > 100 ppm) as compared with triton-x100 as positive control. In conclusion, the obtained results of this study justify the use of these plants in traditional medicine and indicate a promising potential for the development of medicinal agents from them.