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Title: Studies on the phenolic pungent principles in plants and cultures of Zingiber officinale Roscoe
Author: Zarate-Mendez, Rafael
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1994
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It was confirmed that the PPPs of ginger are present in the underground parts of the plant, chiefly in the rhizome, but these compounds also appear to a much lesser extent in the adventitious roots. The major constituents of this pungent fraction are a homologous series of [6]gingerol (4,8,10,12) and [6]shogaol (4,6,8). These secondary compounds occur together with flavonoid-like compounds and constituents of the essential oil of the spice in the yellow pigmented cells which are also storage locations for oil. It has been shown that a positive correlation exists between the number of these yellow cells and the amount of [6]gingerol. A range of culture systems was established in order to study the metabolism of these PPPs. Callus cultures, initiated from emerging axillary buds taken from the rhizome, displayed a number of coloured cells initially but the amount of PPPs per g fw declined sharply together with the number of coloured cells per section as the cultures aged. However, when the data were plotted in a per explant basis an increase was observed. Attempts to influence the production and accumulation of these secondary compounds in differentiating cultures (roots, shoots and plantlets) were partially successful. Generally, on a per g fw basis there was a similar response to that observed during callus induction in which there was a decrease in the amounts of PPPs and also in the number of yellow cells per section. Conversely when the amounts of PPPs were expressed per explant a clear increase was observed which was higher than that obtained during callus induction. Additionally, regenerated plants with mini-rhizomes contained higher amounts of these pungent principles suggesting that higher differentiated structures were necessary for a higher accumulation Studies with suspension cultures showed that in some instances the PPPs accumulated after the cessation of growth (20-30d) and were released into the medium; although in other cultures it was shown that these compounds were retained within the cells and appeared during the early stages of growth. Manipulation of the culture medium by the addition of glutamine did not prevent variation in culture pH, and failed to increase the amounts of [6]gingerol and related compounds. Increasing the concentration of sucrose in the culture medium depressed production of the PPPs. Attempts to boost production by the addition of sunflower oil to suspension cultures, to remove the PPPs from the medium, resulted in the appearance of detectable amounts of these compounds within the added sunflower oil. However, overall product yield was not increased. Conjugated forms of [6]gingerol and related compounds were produced in response to the addition of [6]gingerol to suspension cultures.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available