Isolation of a Marker Olean-12-en-28-butanol Derivative from Viscum continuum E. Mey. Ex Sprague and the Evaluation of Its Antioxidant and Antimicrobial Potentials.

Viscum continuum E. Mey. Ex Sprague (Mistletoe) is a semi-parasitic plant that grows on the branches of other trees with reported numerous biological activities. This study was aimed at isolating a compound/s that will be used as a standard reference for quality control of South African-based commercialized mistletoe products and to further perform antioxidant and antimicrobial tests on the isolated compound. A dried sample of mistletoe was ground and extracted successively with hexane, dichloromethane (DCM), acetone and methanol using a serial exhaustive cold maceration procedure. The compound was isolated using column chromatography, and its chemical structure was elucidated using two-dimensional nuclear magnetic resonance (2D NMR) and ultrahigh-performance liquid chromatography-mass spectrometry (UPLC-MS). The antioxidant activity of the compound was determined using DPPH, hydrogen radical scavenging activity and reducing power assays, whereas antimicrobial activity was assessed using the minimum inhibitory concentration (MIC) method. Subjection of the DCM extract to column chromatography resulted in the isolation of a compound elucidated as olean-12-en-28-butanol-1-one, 3-hydroxy-4,4,10, 14, 20-pentamethyl (D4). Both the DPPH, H₂O₂ radical scavenging activity and reducing power assays revealed a significant antioxidant potential of compound D4 with an IC₅₀ of 0.701 mg/mL, lower than that of gallic acid (0.793 mg/mL) for the H₂O₂ radical scavenging assay. The results also indicated good antibacterial activity of D4 with an IC₅₀ of 0.25 mg/mL, compared to ciprofloxacin with an IC₅₀ of 0.0039 mg/mL, against two Gram-negative (Pseudomonas aeruginosa, Escherichia coli) and three Gram-positive (Streptococcus pyogenes, Bacillus cereus and Staphylococcus aureus) bacteria. This study is the first to report on the isolation of the olean-12-en-28-butanol derivative from mistletoe of the South African ecotype. [ABSTRACT FROM AUTHOR]