Thursday 4 October 2018

Antimicrobial Properties of Plants of Chungtia Village Used Customarily to Treat Skin Related Ailments: From Antimicrobial Screening to Isolation of Active Compounds: (AOICS) - Lupine Publishers

Antimicrobial Properties of Plants of Chungtia Village Used Customarily to Treat Skin Related Ailments: From Antimicrobial Screening to Isolation of Active Compounds by Teresa Malewska in Archives of organic and inorganic chemical sciences in Lupine Publishers

Ethno pharmacological relevance: Chungtia villagers of Nagaland, India, have a strong reliance on plants as medicines. Previous studies have shown that 31 Chungtia medicinal plants (and parts therein) used customarily for skin related treatments possess antimicrobial properties against skin pathogens, strongly supporting the use of these plants by the Chungtia villagers. Five plants, namely Albizia lucidior, Begonia picta, Cassia floribunda, Holboellia latifolia and Maesa indica have no previous studies on their antimicrobial properties, while Prunus persica has only antimicrobial activity reported on its fruit, with no reports on its roots, which are used by the Chungtia villagers. The aim of the study was to investigate these six plants for their antimicrobial properties against dermatologically relevant pathogens and undertake phytochemical analysis of the most active species, Prunus persica.
Materials and Methods: 70% aqueous ethanoic extracts were prepared of leaves of B. picta, C. floribunda, H. latifolia and M. indica and roots of A. lucidior and P. persica. The crude extract of P. persica was successively partitioned between water and n-hexane, dichloromethane (DCM) and ethyl acetate (EtOAc). TLC bioautography guided fractionation using column chromatography of the n-hexane and EtOAc partition afforded five compounds. The structures of the compounds were elucidated by 1D and 2D NMR spectroscopic techniques and comparison with published data. The crude extract and partitioned fractions of P. persica as well as the isolated compounds were screened against antibiotic sensitive and resistant strains of Staphylococcus aureus and Escherichia coli as well as antibiotic sensitive Pseudomonas aeruginosa, Streptococcus pyogenes, Salmonella typhimurium and the fungus C. albicans using the MTT (3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) microtitre dilution and disc diffusion assay methods.
Results: All of the plant aqueous ethanolic extracts exhibited antibacterial activity against at least two of the tested microorganism. The most noteworthy activity was shown by P. persica root extract against antibiotic sensitive as well as resistant (methicillin resistant [MRSA] and multi drug resistant [MDRSA]) strains of S. aureus (0.156mg/mL for all tested strains). None of the plants were active against the fungus C. albicans. This is the first report of antibacterial activity for all of these plants except for P. persica of which the fruit has been previously reported to be anti bacterially active. The partitioned fractions of P.persica showed antibacterial activity, with the highest antimicrobial activity for the EtOAc fraction with MIC 312μg/mL (susceptible as well as resistant strains of S.aureus), followed by n-hexane MIC 625μg/mL (susceptible S. aureus) and MIC 312μg/mL (MRSA and MDRSA). Bioassay guided fractionation of the EtOAc partition resulted in isolation of ent-epiafzelechin-(2α→O→7, 4α→8)-(-)-ent-afzelechin (1), afzelechin (2), Caffeic acid phenylethyl ester (3) and Gallic acid (4). GC-MS analysis of the n-hexane extract showed the presence of the antibacterial compounds palmitic acid, linoleic acid and oleic acid. Bioassay guided fractionation of the n-hexane partition resulted in isolation of three ant bacterially active compounds: α-cyanobenzyl benzoate (4), MIC 0.78μg/mL for susceptible and resistant S. aureus strains, MIC 312μg/mL for susceptible and resistant E. coli strains and MIC 625μg/mL for P. aeruginosa), β-sitosterol (5) MIC 2500μg/mL for susceptible and resistant S. aureus strains and antibiotic susceptible E. coli, MIC 625μg/mL for antibiotic susceptible S. typhimurium and MIC 1250μg/mL for antibiotic susceptible P. aeruginosa) and stigmast-4- en-3-one (6) MIC 156μg/mL for susceptible and resistant S. aureus strains, MIC 312μg/mL for antibiotic susceptible E. coli, MIC 625μg/mL for antibiotic susceptible S. typhimurium and MIC 1250μg/mL for antibiotic susceptible P. aeruginosa). This is the first report for antibacterial activity for α-cyanobenzyl benzoate and stigmast-4-en-3-one.
Conclusion: Aqueous ethanolic extracts of six Chungtia medicinal plants used for skin related ailments were found to have antibacterial properties against dermatologically relevant bacteria, supporting their customary uses by Chungtia villagers. Good antibacterial activity of the EtOAc and n-hexane partitioned fractions from the P. persica root extract and the isolated compounds ent-epiafzelechin-(2α→O→7, 4α→8)-(-)-ent-afzelechin, α-cyanobenzyl benzoate, β-sitosterol and stigmast-4-en-3-one as well as antibacterially active compounds identified from the GC- MS studies further supports the customary use of roots of this species in treating skin related ailments.

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