Propagation of vernonia amygdalina Del. and evaluation of biological activity and chemical constituents from different sources

Chen, Mei Yin (2016) Propagation of vernonia amygdalina Del. and evaluation of biological activity and chemical constituents from different sources. PhD thesis, Universiti Malaysia Sarawak(UNIMAS).

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Abstract

ue to the demand of medicinal plants in the nutraceutical and pharmaceutical industries, multi-disciplinary studies on medicinal plants are required to fully exploit the potential of these resources. Vernonia amygdalina Del. or bitter leaf is an ethnomedicinal plant from tropical Africa that is also cultivated in Malaysia. This study provides an overview of the suitable cultivation conditions of this medicinal plant and investigated the possible use of plant cell culture techniques to produce biologically active plant secondary metabolites. Evaluation of biological activity and chemical constituents was conducted to compare bitter leaf extracts obtained from different sources. Findings from this study has shown that bitter leaf is an easy-to-root species. Stem cuttings of bitter leaf with longer lengths, leaf retention, and either untreated with plant growth regulator or treated with 50 ppm of indole-3-butyric acid (IBA) recorded an overall better rooting response. Further studies showed that it is a light-demanding plant and intolerant towards heavy shading. Recommended cultivation conditions for maximum biomass production is under 100% sunlight and supplemented with 100 – 300 mg/L of nitrogen fertiliser. The plant also recorded better survival rate in a mixture of soil and sand (1:1) as compared to cocopeat potting medium. Plant cell cultures of bitter leaf were successfully established using plant growth regulators. Supplementation of 2, 4-dichlorophenoxyacetic acid (2, 4-D) (0.1 – 2.0 mg/L) and Kinetin (1.0 – 2.0 mg/L) in combination with 2, 4-D (0.5 – 2.0 mg/L) into Murashige and Skoog (MS) medium induced 78 - 100% callusing response from leaf explants after eight weeks. Treatment of 0.5 mg/L of 2, 4-D and 1.0 mg/L Kinetin in combination with 2.0 mg/L of 2, 4-D had induced higher fresh (11.27 - 11.91 g) and dry weights (0.37 - 0.39 g) of callus cultures after eight weeks. Treatment of 0.5 mg/L of 2, 4-D had induced higher fresh (8.76 g) and dry weights (0.39 g) of cell suspension cultures after eight weeks. iv Biological activity of bitter leaf extracts was evaluated using antimicrobial susceptibility test and brine shrimp (Artemia salina) lethality test which showed that leaf and stem extracts of bitter leaf have antibacterial properties, while callus extract has cytotoxic properties. Chemical constituents of bitter leaf extracts were evaluated using Gas Chromatography-Mass Spectrometry (GC-MS) and showed that majority of the detected chemical constituents were aliphatic alkanes. Different field conditions influenced the content of chemical constituents. Chloroalkanes were dominant in the extracts of callus and cell suspension cultures.

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