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Bioactive compounds from tropical plants
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Type
Thesis
Author
Liu, Ying Hong
Supervisor
Chia, Lian Sai
Abstract
The terpenoids are a large and diverse class of naturally occurring organic chemicals similar to terpenes, derived from five-carbon isoprene units assembled and modified in thousand of ways. These lipids can be found in all classes of living things, and are the largest group of natural products. Plant terpenoids are extensively used for their aromatic qualities. They play a role in traditional herbal remedies and are under investigation for antibacterial, antineoplastic and other pharmaceutical effects.
There are some terpenoids in essential oils from tropical plants. This study tried to extract and identify terpenoids from tropical essential oils by using different methods. Due to the low content and high evaporating characters of essential oils, this study did not purify the terpenoids in the essential oils if they are not new.
A lot of diterpenoids are contained in Isodon genus plants, some of the compounds have outstanding anti-fungal, anti-bacterial and anti cancer effects. The most popular topic in current research front is the development of diterpenoids as potential anti cancer drugs. This study isolated, purified and identified some compounds especially diterpenoids from the tropical Isodon genus plants; screened the toxicity of selected diterpenoids which are either new or novel or have anticancer functional groups, and studied further on the anti cancer effect on one of the compounds.
Polygonum odoratum Lour (Laksa), Phaeomeria speciosa (Blume) Koord, Wedelia triolbata and Syzygium polyanthum (Wight) Waplers are aromatic tropical plants. They are widely cultivated in Southern East Asia. However, there are no reports on the volatile components from these plants. From our preliminary work, it appears that these plants contain quite high content of essential oils. As essential oils are very important and useful, it is highly desirable to investigate the volatile compounds from these plants. The qualitative and quantitative results of volatile essential oil constituents from these four tropical plants were obtained by different methods like chromatography fraction and spectroscopic techniques. In this study, it has been isolated and identified more than 46 compounds from Polygomum adoratum Lour leaf, 29 compounds from Phaeomeria speciosa (Blume) Koord, 86 compounds from Wedelia triolbata and 58 compounds from Syzygium polyanthum (Wight) Waplers leaf all obtained by steam distillation. Meanwhile, only 57 compounds from Wedelia triolbata and 36 compounds from Syzygium polyanthum (Wight) Waplers leaf essential oil were identified using hexane extraction. This study has isolated and identified most of the volatile components in these plants and found out that the essential oils from these tropical plants normally have more long chain aldehydes or alcohols than in those from other areas. This may be related to the tropical climate and environmental they are growing in.
Isodon genus plants are widely present in Africa, Asia and Australia. Researchers in China and Japan have studied many species of their local Isodon plants. It was found that there are lots of diterpenoids in this genus which are bioactive. This study started with Isodon coesta Hara, a tropical plant which has been studied elsewhere before. Two new diterpenoids and three phenolics have been isolated from this plant. It is the first time to isolate abietane ortho-quinones from this species and it is the second time to obtain ortho diterpenoids from Isodon genus plants.
The other two Isodon plants investigated in this study are tropical Isodon Iophanthodies var. gerdianus [Bentham] H. Hara and a non-tropical Isodon rubescens (Hemsl.) Hara. A novel diterpenoid compound, (which has a new diterpenoid skeleton and is named Unirubescensin), and a new diterpenoid d-22 have been identified. So far, more than 55 compounds have been isolated and 40 bioactive compounds were identified from the three Isodon plants. Among them, 30 compounds are diterpenoids, with one novel compound and four new compounds.
In this study, the cytotoxicity of the 15 selected diterpenoids had been carried out. The results showed that the 15 selected diterpenoids had a great anticancer potential. After comparing the cytotoxic results, one diterpenoid compound was selected for further anticancer pharmacological study and it showed great anticancer potential.
There are some terpenoids in essential oils from tropical plants. This study tried to extract and identify terpenoids from tropical essential oils by using different methods. Due to the low content and high evaporating characters of essential oils, this study did not purify the terpenoids in the essential oils if they are not new.
A lot of diterpenoids are contained in Isodon genus plants, some of the compounds have outstanding anti-fungal, anti-bacterial and anti cancer effects. The most popular topic in current research front is the development of diterpenoids as potential anti cancer drugs. This study isolated, purified and identified some compounds especially diterpenoids from the tropical Isodon genus plants; screened the toxicity of selected diterpenoids which are either new or novel or have anticancer functional groups, and studied further on the anti cancer effect on one of the compounds.
Polygonum odoratum Lour (Laksa), Phaeomeria speciosa (Blume) Koord, Wedelia triolbata and Syzygium polyanthum (Wight) Waplers are aromatic tropical plants. They are widely cultivated in Southern East Asia. However, there are no reports on the volatile components from these plants. From our preliminary work, it appears that these plants contain quite high content of essential oils. As essential oils are very important and useful, it is highly desirable to investigate the volatile compounds from these plants. The qualitative and quantitative results of volatile essential oil constituents from these four tropical plants were obtained by different methods like chromatography fraction and spectroscopic techniques. In this study, it has been isolated and identified more than 46 compounds from Polygomum adoratum Lour leaf, 29 compounds from Phaeomeria speciosa (Blume) Koord, 86 compounds from Wedelia triolbata and 58 compounds from Syzygium polyanthum (Wight) Waplers leaf all obtained by steam distillation. Meanwhile, only 57 compounds from Wedelia triolbata and 36 compounds from Syzygium polyanthum (Wight) Waplers leaf essential oil were identified using hexane extraction. This study has isolated and identified most of the volatile components in these plants and found out that the essential oils from these tropical plants normally have more long chain aldehydes or alcohols than in those from other areas. This may be related to the tropical climate and environmental they are growing in.
Isodon genus plants are widely present in Africa, Asia and Australia. Researchers in China and Japan have studied many species of their local Isodon plants. It was found that there are lots of diterpenoids in this genus which are bioactive. This study started with Isodon coesta Hara, a tropical plant which has been studied elsewhere before. Two new diterpenoids and three phenolics have been isolated from this plant. It is the first time to isolate abietane ortho-quinones from this species and it is the second time to obtain ortho diterpenoids from Isodon genus plants.
The other two Isodon plants investigated in this study are tropical Isodon Iophanthodies var. gerdianus [Bentham] H. Hara and a non-tropical Isodon rubescens (Hemsl.) Hara. A novel diterpenoid compound, (which has a new diterpenoid skeleton and is named Unirubescensin), and a new diterpenoid d-22 have been identified. So far, more than 55 compounds have been isolated and 40 bioactive compounds were identified from the three Isodon plants. Among them, 30 compounds are diterpenoids, with one novel compound and four new compounds.
In this study, the cytotoxicity of the 15 selected diterpenoids had been carried out. The results showed that the 15 selected diterpenoids had a great anticancer potential. After comparing the cytotoxic results, one diterpenoid compound was selected for further anticancer pharmacological study and it showed great anticancer potential.
Date Issued
2008
Call Number
QK898.B54 Liu
Date Submitted
2008