Phytochemical Screening, Antioxidant and Antibacterial Properties of Extracts of Viscum continuum E. Mey. Ex Sprague, a South African Mistletoe

Abstract

Viscum continuum E. Mey. Ex Sprague is a woody evergreen semi-parasitic shrub that grows on the branches of other trees. It is used by African traditional healers for post-stroke management. This study reports on the qualitative phytochemical screening and the antioxidant and antimicrobial activities of Viscum continuum's acetone, methanol, hexane and dichloromethane extracts. Standard protocols for the phytochemical screening of extracts were employed. TLC bio-autography was used for qualitative antioxidants analysis. Assays: 2,2-diphenyl-1-picrylhydrazyl, H₂O₂ free-radical scavenging and ferric chloride reducing power were carried out for quantitative antioxidant analysis. The antimicrobial potential of extracts was screened using disc diffusion, bio-autography and broth micro-dilution. The results indicate the presence of alkaloids, phenolics and tannins in all extracts. Acetone and methanol revealed significant amount of saponins, phenolics, tannins and terpenoids. The extracts exhibited significant antioxidant potential on TLC with positive compound bands at an Rf range of 0.05-0.89. DPPH, H₂O₂ and the reduction of Fe³⁺ to Fe²⁺ assays indicated that methanol extract has a strong antioxidant potential, followed by acetone, DCM and lastly hexane. The extracts of Viscum continuum show the potential to be antibacterial agents. It can be concluded that Viscum continuum extracts contain phytochemicals which are capable of mitigating against chronic health conditions such as cancer, stroke and stress-related and infectious diseases.

Keywords: Mistletoe; antimicrobial; antioxidant; bio-autography.

Figure 1

TLC chromatogram of the dichloromethane (A) and hexane (B) extracts of Mistletoe indicating different phytochemical (plate 1–3) and antioxidant (plate 4) bands. Plates visualized and snapped at white light (1), 255 nm (2), 366 nm (3) and sprayed with 0.2 mM DPPH solution.

Figure 2

TLC chromatogram of the acetone (A) and methanol (B) extracts of Mistletoe indicating different phytochemical bands. Plates visualized and snapped at white light (1), 255 nm (2), 366 nm (3) and sprayed with 0.2 mM DPPH solution (4).

Figure 3

DPPH free-radical scavenging percentage inhibition of Mistletoe extracts and standards. Each value is expressed as mean ± standard deviation (n = 3).

Figure 4

Hydrogen peroxide percentage inhibition of Mistletoe extracts and standards. Each value is expressed as mean ± standard deviation (n = 3).

Figure 5

Percentage reducing power of Mistletoe extracts and standards. Each value is expressed as mean ± standard deviation (n = 3).

Figure 6

TLC direct bio-autography for the detection of antibacterial activity in 1 = Mistletoe tree extracts (control) antimicrobial activity against A. baumani BAA747 (plate 2), S. sense (plate 3), E. faecalis (plate 4) and B. substillis (plate 5). White coloration against purple background indicates inhibition against the test organism.