Genetic diversity, nutritional and biological activity of Momordica cochinchinensis (Cucurbitaceae)

Wimalasiri, D 2015, Genetic diversity, nutritional and biological activity of Momordica cochinchinensis (Cucurbitaceae), Doctor of Philosophy (PhD), Applied Science, RMIT University.


Document type: Thesis
Collection: Theses

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Title Genetic diversity, nutritional and biological activity of Momordica cochinchinensis (Cucurbitaceae)
Author(s) Wimalasiri, D
Year 2015
Abstract Momordica cochinchinensis (Lour.) Spreng belongs in the Cucurbitaceae family and is geographically restricted to South East Asia. The fruit possesses the highest amount of nutritionally important carotenoids (lycopene and ß-carotene) of all known fruits and vegetables including tomatoes and carrots by more than 200 and 54 times, respectively. Little information is available on the influence of genetic diversity and eco-geographical differences on the nutritional and medicinal potential of the fruit. This information is essential to assist future agricultural practices for the commercialisation of M. cochinchinensis as a new fruit in the medicine, food and nutrition industries. This thesis elucidated the variation in morphology, genetics, nutritional content (carotenoids) and biological activity (anticancer) of M. cochinchinensis collected from Vietnam, Thailand and Australia.

M. cochinchinensis was morphologically and genetically diverse and the highest diversity was in Vietnam, indicating the presence of a diverse gene pool which contributed to superior nutritional and medicinal varieties. Molecular profiling of M. cochinchinensis samples based on morphology and molecular analyses (ISSR and RAPD) were in agreement and clustered the samples based on the country of origin. This study also indicated that the previously unknown origin of the Australian samples was from Southern Vietnam, an important finding for tracking the parentage of the plants grown in Australia and analysing the gene flow of M. cochinchinensis to Australia.

The lycopene content was greater in samples from the Lam Dong and Lam Ha provinces of Central Vietnam as detected by HPLC and corresponded to larger and heavier seeds of M. cochinchinensis. Northern Vietnam samples possessed the highest levels of combined lycopene and ß-carotene. It is recommended that the varieties from Central and Northern Vietnam should be selected in future plant development for high carotenoids. Carotenoid accumulation was influenced by climatic factors, where lycopene accumulation was greatest at lower temperatures (<14°C) and higher elevations whilst b-carotene accumulation was greatest at temperatures between 27 to 33°C. These growth conditions should be replicated in future agriculture to enhance carotenoid accumulation in the fruit.

Four different analytical methods were investigated to determine the accuracy and potential of analysis of carotenoid content in the M. cochinchinensis aril samples. Colorimetry, which was linked with redness of the aril correlated with higher lycopene concentrations as quantified by chromatography (HPLC, UPLC) and UV-visible spectrophotometry but this was not the case for b-carotene. This method could be used to rapid screen lycopene rich M. cochinchinensis in the field and will be useful for resource-poor farmers.

Water extracts of the aril of M. cochinchinensis had a higher cytotoxicity on breast cancer and melanoma cells than the hexane based extracts. This suggested that the anticancer bioactive compounds extracted from the arils are not the carotenoids. The cytotoxicity of the water-based extract was selective towards breast cancer (MCF7) and melanoma (MM418C1 and D24) cells and not against normal human dermal fibroblast cells (NHDF). Furthermore, treatment of cells with the water extract caused both apoptotic and necrotic cell death. The cytotoxicity of the water extract was greater for samples obtained from Northern and Central Vietnam (>70% of cell death), especially those from the Ha Noi and Lam Dong provinces, respectively. High anticancer activity of the aril extract against melanoma cells were correlated with cool climates with low temperatures (<14°C) and a high precipitation during the driest month, indicating that these conditions facilitated the production of compounds responsible for anticancer activity.

The findings of this study are novel and will assist current and future agricultural practices for the commercialisation of M. cochinchinensis as a new fruit in the medicine, food and nutrition industries.
Degree Doctor of Philosophy (PhD)
Institution RMIT University
School, Department or Centre Applied Science
Subjects Biological Sciences not elsewhere classified
Keyword(s) Momordica cochinchinensis
ß-carotene
Lycopene
Anticancer
Melanoma
Breast cancer
Genetic diversity
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