Antimicrobial, Antioxidant, Anticancer and Cytotoxic Activities of some Sudanese Medicinal Plants

Abstract

Abstract Five plants were selected in the present study on the basis of their known traditional uses in the treatment of various diseases in Sudan. These plants were identified as Cadaba farinose Forssk, Solanum nigrum L., Senna occidentalis (L.) Link., Maerua oblongifolia (Forssk).A.Rich. and Striga hermonthica Qlellile) Benth. Leaves and stems of the plants were ground into fine powder and then extracted by maceration procedures using chloroform and methanol solvents. Active methanol extracts were fractionated using three solvents Acetyl acetate, n- butanol and distilled water. Eighteen extracts and fifteen fractions were investigated for their bioactivity against some pathogenic bacteria and fungi as follow: four different ‘references bacteria: two Gram positive (Bacillus subtilis and Staphylococcus aureus), two Gram negative (Escherichia coli and Salmonella typhi) and against two references fungi (Aspergillus niger and Candida albicans) using the cup plate agar diffusion method. The results have shown that the different extracts have been known to inhibit the growth of certain pathogenic bacteria and fungi. The minimum inhibitory concentrations (l\/lICs) of all methanol and chloroform extracts of the plants against standard bacteria and ftmgi were also determined. It was found that MICs ranged between 2.5-5 (mg\ml) concentration. The antibacterial activity of the three reference antibiotics and the antifungal activity of the two reference drugs were determined against the tested four bacteria and two fungi and their activities were compared to the activities of the plant extracts. It can therefore be suggested that, they are promising antimicrobial agents. Moreover, the eighteen plant extracts were also investigated for their cytotoxicity against the Brine shrimps (Artemia salina L.), the results revealed that, this plant extracts posses strong and moderate cytotoxic effect and this can be considered as anti-tumour, insecticidal or

parasiticidal properties. In vitro cytotoxic assays were carried out using 3T3 NIH mouse embryo fibroblast cell line and CC-1, a rat Wistar hepatocyte cell line. The MTT based assays for cytotoxicity indicated that, all of leaves and stems extracrs of tested plants were non toxic for 3T3 and CC-1 cell line (CC50> 100 pg/ml), except methanol leaves extract of Solanum nigrum which showed high percentage of growth inhibition for both 3T3 and CC-1 cell lines with CC50 of 17.37 pg/ml and 75.7pg/ml respectively. The leaves and stems of the methanol extracts of Solanum nigrum were further fractionated using three solvent systems; Acetyl acetate, n— Butanol and Aqueous. These fractions were tested for their cytotoxicity against 3T3 NIH mouse embryo fibroblast cell line using different fraction concentrations 100, 10.0, 1.00pg/mL and MTT assay. The results obtained indicated that stems acetyl acetate and aqueous fractions were non toxic with CC50 > l00ug/ml. While the other fractions showed cytotoxicities in a dose dependend manner. Furthermore, the five plants that investigated for their activity on the two cancer cell lines which were Hela (cervical cancer) and PC3 (prostate cancer), the highest percentage of growth inhibition was obtained by methanolic extract of Solanum nigrum stems on Hela cell line and PC3 which were 91.11 and 80.49% respectively in comparison with control positive 89.07% inhibition. Followed by methanolic extract of Solanum nigrum leaves on Hela cell line and PC3 with growth inhibition percentages of 84.86 and 74.28% inhibition respectively. Therefore, these extracts were fractionated using three solvent systems; Acetyl acetate, n- Butanol and Aqueous. The fractions are tested for their anticancer activity on PC3 prostate cancer cell line and Hela cervical cancer cell line using different fraction concentrations 50, 25 and Spg/ml by MTT assay. The results obtained indicated that the most active fraction was leaves n- Butanol fraction which inhibits both type of cancer cells with inhibition

growth percentage of 99.81 on PC3 and 98.59% on Hela cell line with IC50 5.92ug/ml and l.6pg/ml respectively. Followed by stems n-Butanol and leaves Acetyl acetate fraction, whereas, leaves aqueous, stems aqueous and stems Acetyl acetate fiaction were inactive on the tested cancer cell lines with IC5@ > 50pg/ml. Antioxidant activities of the tested plant extracts were determined using DPPH assay and Metal chelating activity, the results obtained indicated that methanolic extract of Solanum nigrum leaves has shown the highest scavenging percentage against DPPH (85%). It could be concluded that the plant extracts that used were screened for the presence of phytochemical constituents. The results showed that alkaloids, flavonoids, saponins, tannins, sterols, triterpens, and coumarins are present in all of the tested plants, while anthraquinones were absent.