Chemo-morphological characterisation and some biological activities of pelargonium sidoides DC.
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Date
2013
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University of Zululand
Abstract
Pelargonium sidoides DC (Geraniaceae) is one of several medicinal plants indigenous to South Africa. Various concoctions prepared from the plant are used for the treatment of tuberculosis, diarrhea, gonorrhea and fevers. The aim of this study was to evaluate the variability in qualitative and quantitative traits in P. sidoides accessions, correlate different morphotypes with the phytochemical content, and to the antimicrobial activity of P. sidoides extracts.
Morphological characterisation of accessions of P. sidoides was done using IPGRI/IITA/BAMBNET list for Bambara groundnut. Principal Component Analysis (PCA) and Cluster Analysis (CA) were used to evaluate the morphological variability and to reveal the groups of different morphotypes. The PCA revealed that the first three principal components exhibited Eigenvalues greater than 1 and explained 74.170% of the total variability, contributing the entire variable to the morphological variation of the accessions established at the University of Zululand. Cluster analysis was able to group the morphotypes into two major groups with each group having two sub-groups. Nine groups of the morphotypes were selected and screened for coumarins (umckalin, esculin and scopoletin) using Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC). Coumarins are known to exhibit moderate antibacterial and significant immunomodulatory capabilities. Variation was observed in the phytochemical content (umckalin) of morphotypes of P. sidoides. The content of umckalin varied between 13.90 mg/ml and 4.41 mg/ml in the roots of morphotypes of P. sidoides and 0.15mg/ml and 3.90 mg/ml in the leaves of morphotypes of P. sidoides.
Methanolic extracts from leaves and roots of selected morphotypes were screened for antimicrobial activity against Escherichia coli ATCC 8739, Staphylococcus aureus ATTC 6538, Shigella flexineri and Salmonella ssp. The antimicrobial activity was determined by agar-well diffusion method. The minimum inhibitory concentration (MIC) of active extracts was determined using the micro-plate dilution assay. Significant variation was observed among all accessions for all the investigated traits. The high morphological
variation that was observed among morphotypes did not affect the phytochemical content and antimicrobial activity of P. sidoides. Most of the extracts showed relatively high antimicrobial activity against the tested bacterial strains with the inhibition zones ranging between 8.0 and 12.0 mm for leaves and 15.0 and 20.5 mm for the roots. The MIC values for active extracts ranged between 1.5 to 5 mg/ml.
In vivo antidiarrheal activity of P.sidoides methanolic root extracts in rats (Sprague-Dawley) was investigated. In the castor oil induced diarrhea experiment, the rats that did not receive the P. sidoides plant extracts showed typical diarrheal signs, stools were too wet. P. sidoides extracts inhibited castor oil induced diarrhea in Sprague-Dawley rats at doses of 100, 200 and 400 mg/kg. The extracts reduced the weight of feacal pellets with extracts treated groups showing lower diarrheal severity than control rats.
The variants utilised in this study seem to have similar compounds and could be all utilized in future research on cultivation practices. It was concluded that leaves of the plants may be harvested instead of roots to minimise the complete removal of the plants. The results of this study suggest that P. sidoides extracts possess anti-microbial activities against some of the tested microorganisms which are significant pathogens in humans. P. sidoides roots have the potential for the treatment of diarrhea.
Description
Dissertation submitted in fulfilment of the requirements for the Degree of Master of Science in Agriculture (Agronomy) in the Department of Agriculture Faculty of Science and Agriculture at the University of Zululand, South Africa, 2013.
Keywords
Morphological characterisation, Indigenous plants -- South Africa, Medicinal plants -- South Africa