Articles
Phenolic profiling and antibacterial evaluation of indigenous South African medicinal plant extracts for postharvest applications
Article number
1466_22
Pages
175 – 184
Language
English
Abstract
Microbial contamination and oxidative processes are the primary causes of postharvest deterioration, underscoring the urgent need for safe preservation strategies.
Therefore, this study investigated the influence of solvent polarity (30, 50, and 70% ethanol) on the recovery of phenolic composition and antibacterial activity of leaf extracts from Bauhinia galpinii, Mystroxylon aethiopicum, and Strychnos madagascariensis as a potential postharvest preservation strategy.
Leaf extracts were prepared using ethanol:distilled water solvents at varying polarity and evaluated for total phenolic and flavonoid contents, Fourier transform infrared (FTIR) spectral characteristics and antibacterial activity against Escherichia coli and Staphylococcus aureus using agar well diffusion and minimum inhibitory/bactericidal concentration assays.
The efficiency of the extraction was observed to be solvent and extract-dependent, where 50% ethanol enhanced phenolic and flavonoid recovery, particularly in B. galpinii with values of 63.17 mg GAE 100 mL‑1 and 81.89 mg CE 100 mL‑1, respectively.
FTIR spectra revealed solvent-dependent variations in hydroxyl, aromatic, and carbonyl functional group intensities, confirming compositional differences among extracts.
Although inhibition zones were generally weak, the 30% ethanol extract of B. galpinii demonstrated bactericidal activity against Escherichia coli and Staphylococcus aureus (MIC 6.25 mg mL‑1 and MBC 6.25 mg mL‑1), respectively.
Overall, solvent polarity significantly influenced phytochemical recovery and bioactivity, with B. galpinii between 30 and 50% ethanol showing the greatest potential for postharvest preservation.
Therefore, this study investigated the influence of solvent polarity (30, 50, and 70% ethanol) on the recovery of phenolic composition and antibacterial activity of leaf extracts from Bauhinia galpinii, Mystroxylon aethiopicum, and Strychnos madagascariensis as a potential postharvest preservation strategy.
Leaf extracts were prepared using ethanol:distilled water solvents at varying polarity and evaluated for total phenolic and flavonoid contents, Fourier transform infrared (FTIR) spectral characteristics and antibacterial activity against Escherichia coli and Staphylococcus aureus using agar well diffusion and minimum inhibitory/bactericidal concentration assays.
The efficiency of the extraction was observed to be solvent and extract-dependent, where 50% ethanol enhanced phenolic and flavonoid recovery, particularly in B. galpinii with values of 63.17 mg GAE 100 mL‑1 and 81.89 mg CE 100 mL‑1, respectively.
FTIR spectra revealed solvent-dependent variations in hydroxyl, aromatic, and carbonyl functional group intensities, confirming compositional differences among extracts.
Although inhibition zones were generally weak, the 30% ethanol extract of B. galpinii demonstrated bactericidal activity against Escherichia coli and Staphylococcus aureus (MIC 6.25 mg mL‑1 and MBC 6.25 mg mL‑1), respectively.
Overall, solvent polarity significantly influenced phytochemical recovery and bioactivity, with B. galpinii between 30 and 50% ethanol showing the greatest potential for postharvest preservation.
Publication
Authors
K.S. Methula, K.C. Ezeora, O.A. Fawole
Keywords
medicinal plants, phenolic content, antibacterial activity, FTIR, postharvest preservation
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