Among the various medicinal herbs, some species are of particular interest because they produce certain phytochemicals which have significant therapeutic importance against various diseases. These metabolites are exploited for manufacturing of drug or for other technological development. Peppermint (Mentha piperita L.) and field mint (Mentha arvensis L.), two perennial herbs of the family Lamiaceae, are medicinal plants of high importance because of their phenolic components. Rosmarinic acid is a phenolic acid obtained in these plants with anti-viral, anti-bacterial, anti-inflammatory and anti-oxidant activity. Conservation measures should be taken along with mass propagation to protect this plant from future extinction due to indiscriminate use of these metabolites of plant origin. In vitro propagation is the suitable way out for rapid multiplication of these plants as well as fruitful isolation of necessary secondary metabolites. The present study deals with the above aspects.
The thesis is divided into four major chapters.
Chapter one includes the study of plant morphology and karyotype of five populations of two species of Mentha to reveal the variation at the morphological as well as the chromosomal levels.
Chapter two contains shoot bud multiplication, in vitro plant regeneration in one of the population of Mentha piperita L. and Mentha arvensis L. In vitro flowering was also observed in Mentha piperita L. This study revealed that different types and concentrations of exogenous cytokinins had different effects on growth and multiplication of two species of Mentha.
Chapter three is divided in to two major sections:
First section (section 3.1) deals with extraction of total phenol and rosmarinic acid from field grown plants of two species of Mentha (Population 1). Qualitative detection of rosmarinic acid was done through Thin Layer Chromatography (TLC) and Quantitative estimation was done using High Performance Liquid Chromatography (HPLC). Total phenol content was measured through spectrophotometry.
Second section (section 3.2) deals with qualitative and quantitative analysis of rosmarinic acid and quantitative analysis of total phenol content in micropropagated plants after addition of two precursor molecules namely tyrosine and phenylalanine and one elicitor molecule salicylic acid. This study revealed that external application of precursor and elicitor molecules affected the biomass growth, multiplication rate and production of total phenol and rosmarinic acid content in cultured shoots with respect to control.
Chapter four involves the study of total protein content, qualitative analysis of total protein profile by Poly Acrylamide Gel Electrophoresis (PAGE) and isozyme such as Esterase analysis to characterize the different clones at biochemical level. Therefore the four chapters along with general introduction presents an idea about the Mentha plant along with micropropagation of two species of it and evaluation of the regenerated clones at cytological and biochemical level to characterize the differences with field grown plants. An attempt had also been made to produce continuously and enhance the rosmarinic acid level in cultured plants by applying precursors and elicitors exogenously during culture.