Evaluation of the antioxidant, antibacterial, and antiproliferative activities of the acetone extract of the roots of Senna italica (Fabaceae)

Abstract

Senna italica, a member of the Fabaceae family (subfamily Caesalpinaceae), is widely used traditionally to treat a number of disease conditions, such as sexually transmitted diseases and some forms of intestinal complications. The roots of Senna italica were collected from Zebediela subregion, Limpopo province (S.A), powdered and extracted with acetone by cold/shaking extraction method. The phytochemical composition of the extract was determined by thin layer chromatography (TLC). The chromatograms were visualised with vanillin-sulphuric acid and p-anisaldehyde reagents. The total phenolic content of the extract was determined by Folin-Ciocalteu method and expressed as TAE/g dry weight. The extract was assayed for the in vitro anticancer activity using Jurkat T cells, antioxidant activity using DPPH assay and antibacterial activity by bioautographic method and the microtitre plate method. The acetone extract of the roots of Senna italica inhibited the growth of Jurkat T cells in a dose- and time-dependent manner. The extract also had free radical scavenging activity as well as reasonable antibacterial activity against Pseudomonas aeruginosa, Enterococcus faecalis, Escherichia coli and Staphylococcus aureus with MICs ranging from 0,08 to 0.16 mg/ml in the same order as ampicillin the positive control. The biological activities observed in the acetone extract validated the ethnomedicinal use of Senna italica.

Keywords: Antibacterial; Antioxidant; Antiproliferative; Senna italica.

Figure 1a

The chromatograms of crude acetone root extract of Senna italica separated by the three different solvent systems. with BEA (non-polar), CEF (intermediate polarity) and EMW (polar). The individual compounds were visualized with p-anisaldehyde.

Figure 1b

The chromatograms of crude acetone root extract of Senna italica separated with BEA, CEF and EMW and visualized with vanillin-sulphuric acid.

Figure 2

The UV-Visible spectral profile of the acetone extract of the roots of Senna italica. Major absorption of light was shown at a range of 240 nm to 450 nm which suggests the presence of flavonoids, prosalins or caretenoids.

Figure 3a

The effect of the acetone extract of the roots of Senna italica on the proliferation of Jurkat T cells treated with increasing concentrations of crude acetone extract at 24 h intervals (* p < 0.01). Cell growth was inhibited in a dose- and time-dependent manner.

Figure 3b

The effect of the acetone extract of the roots of Senna italica on viability of Jurkat T cells treated with increasing concentrations of crude acetone extract at 24 h intervals (* p < 0.01). Cell viability was reduced in a dose- and time-dependent manner.

Figure 4a

The free radical scavenging power of the acetone extract of the roots of Senna italica evaluated by the DPPH assay. The yellow zones on the chromatograms developed with the different solvent systems indicate compounds with free radical scavenging activity.

Figure 4b

The comparison of the free radical scavenging power of the acetoneextract of the roots of Senna italica with vitamin C (* p< 0.01). Low absorbance values indicate high free radical scavenging power.

Figure 5a

The antibacterial activity of the acetone extract of the roots of Senna italica evaluated on E. faecalis. The clear zones on the bioautograms indicate areas where inhibition of bacterial growth occurred.

Figure 5b

The antibacterial activity of the acetone extract of the roots of Senna italica evaluated on S. aureus. The clear zones on the chromatograms indicate areas where inhibition of bacterial growth had occurred.