OBJECTIVE: In this study, we attempted to isolate and identify the active compound from the aqueous extract of B. orientale.
MATERIALS AND METHODS: Aqueous extract of B. orientale was subjected to repeated MCI gel chromatography, Sephadex-LH-20, Chromatorex C18 and semi-preparative high performance liquid chromatography and was characterized using nuclear magnetic resonance and electrospray ionization mass-spectrometry spectroscopic methods. Antioxidant activity was determined using 2, 2-diphenyl-1-picrylhydrazyl radical scavenging assay. Antibacterial assays were conducted using disc diffusion whereas the minimum inhibitory concentration (MIC) and minimum bactericidal concentration were determined using the broth microdilution assay. Cytotoxicity was assessed using thiazolylblue tetrazoliumbromide.
RESULTS: A polymeric proanthocyanidin consisting of 2-12 epicatechin extension units and epigallocathecin terminal units linked at C4-C8 was elucidated. Bioactivity studies showed strong radical scavenging activity (IC50 = 5.6 ± 0.1 µg/mL), antibacterial activity (MIC = 31.3-62.5 µg/mL) against five gram-positive bacteria and selective cytotoxicity against HT29 colon cancer cells (IC50 = 7.0 ± 0.3 µg/mL).
CONCLUSION: According to our results, the proanthocyanidin of B. orientale demonstrated its potential as a natural source of antioxidant with antibacterial and anti-cancer properties.
SUMMARY: A bioactive proanthocyanidin was isolated from the aqueous extract of medicinal fern Blechnum orientale Linn and the structure was elucidated using NMR and ESI-MS spectral studies.The proanthocyanidin compound possessed strong radical scavenging activity (IC50 5.6 ± 0.1 µg/mL)The proanthocyaniding compound showed bactericidal activity against five gram-positive bacteria inclusive of MRSA (minimum inhibitory concentration, MIC and minimum bactericidal concentration, MBC 31.3-62.5 µg/mL).The proanthocyanidin compound is strongly cytotoxic towards cancer cells HT29 (IC50 7.0 ± 0.3 µg/mL), HepG2 (IC50 16 µg/mL) and HCT116 (IC50 20 µg/mL) while weakly cytotoxic towards the non-malignant Chang cells (IC50 48 µg/mL). Abbreviation used: CC: Column chromatography, DP: degree of polymerization, DPPH: 2,2-diphenyl-1-picrylhydrazyl, ESI-MS: electronsprayionisation mass-spectrometry, MBC: Minimum bactericidal concentration, MIC: Minimum inhibitory concentration, MTT: Thiazolyl Blue Tetrazolium Bromide, MRSA: methicillin-resistant Staphylococcus aureus, NMR: nuclear magnetic resonance, TLC: thin layer chromatography, PD: prodelphinidin.
RESULTS: The results of the study show that total phenolic content (TPC) in soil and leaves of three species of Macaranga were highest in TPSF followed by freshwater swamp forest and flooded limestone forest, then dry land sites. Highest TPC values were associated with acidity (in TPSF) and waterlogging (in flooded forests). Moreover, phenolic compounds are rapidly leached from fallen senescent leaves, and could be reabsorbed by tree roots and converted into more complex phenolics within the leaves.
CONCLUSIONS: Extreme conditions-waterlogging and acidity-may facilitate uptake and synthesis of protective phenolic compounds which are essential for impeded decomposition of organic matter in TPSF. Conversely, the ongoing drainage and degradation of TPSF, particularly for conversion to oil palm plantations, reverses the conditions necessary for peat accretion and carbon sequestration.