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Chemistry and bioactivity studies of African medicinal plants Ximenia caffra, Hibiscus sabdariffa and Combretum micranthum

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Title
Chemistry and bioactivity studies of African medicinal plants Ximenia caffra, Hibiscus sabdariffa and Combretum micranthum
Name (type = personal)
NamePart (type = family)
Zhen
NamePart (type = given)
Jing
NamePart (type = date)
1989-
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Jing Zhen
Role
RoleTerm (authority = RULIB)
author
Name (type = personal)
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Simon
NamePart (type = given)
James E
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James E Simon
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Advisory Committee
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chair
Name (type = personal)
NamePart (type = family)
Wu
NamePart (type = given)
Qing-Li
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Qing-Li Wu
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Advisory Committee
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internal member
Name (type = personal)
NamePart (type = family)
LaVoie
NamePart (type = given)
Edmond J
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Edmond J LaVoie
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Advisory Committee
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internal member
Name (type = personal)
NamePart (type = family)
HUANG
NamePart (type = given)
QINGRONG
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QINGRONG HUANG
Affiliation
Advisory Committee
Role
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outside member
Name (type = corporate)
NamePart
Rutgers University
Role
RoleTerm (authority = RULIB)
degree grantor
Name (type = corporate)
NamePart
Graduate School - New Brunswick
Role
RoleTerm (authority = RULIB)
school
TypeOfResource
Text
Genre (authority = marcgt)
theses
OriginInfo
DateCreated (qualifier = exact)
2016
DateOther (qualifier = exact); (type = degree)
2016-10
CopyrightDate (encoding = w3cdtf); (qualifier = exact)
2016
Place
PlaceTerm (type = code)
xx
Language
LanguageTerm (authority = ISO639-2b); (type = code)
eng
Abstract (type = abstract)
Africa has been and continues to be an important source of medicinal plants yet only a relative few have been extensively studied. Three different traditional African medicinal plants Ximenia caffra, Hibiscus sabdariffa and Combretum micranthum, were selected for phytochemical investigations and potential pharmacological activities. For Ximenia caffra, more than ten polyphenol compounds were identified in the leaf sample using LC/UV/MS profiling, including gallic acid, catechin, quercetin, kaempferol and their derivatives. The antioxidant capacities of leaf extract were determined by Folin-Ciocalteu assay as 261.87 ± 7.11 mg GAE/g and ABTS free radical scavenging assay as 1.46 ± 0.01 mmol TE/g. The anti-proliferative effect of Ximenia caffra leaf extract was measured by MTS assay with IC50 value of 239.0 ± 44.5 µg/ml. Cell-based assays show that the leaf extract inhibits the mRNA expression of pro-inflammatory genes (iL-6, iNOS, and TNF- α) by using RT-qPCR, indicating its anti-inflammatory effects. Further studies suggest that the underlying therapeutic mechanism may involve the suppression of NF-κB, a shared pathway between cell death and inflammation. For Hibiscus sabdariffa, which is originally native to Africa, the phytochemical profile of leaves from 25 different populations from worldwide accessions were determined by LC/MS and compared with each other. Ten polyphenols including neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid, quercetin, kaempferol and their glycosides were identified together with 5-(hydroxymethyl)furfural, some of which were quantified with commercially available standards. The leaves have shown anti-oxidant activities as measured by Folin-Ciocalteu assay and ABTS free radical scavenging assay. Leaves extracts reduced LPS-induced NO production in RAW 264.7 cell in a dose-dependent manner indicating the extract’s potential anti-inflammatory activity. The compound 5- HMF was identified in dried samples and later investigated as a biomarker of the freshness of the leaf samples. For plant Combretum micranthum, in prior phytochemical investigations, our lab identified a group of new skeleton compounds named kinkéloids. As a continuation of this project, two total synthetic methods for these novel compounds kinkéloids A group and B were developed, which were then applied for regioisomers determination, scale-up synthesis and potential analogues synthesis. The key and final step was achieved by Mannich reaction, through which the piperidine moiety coupled to the flavan moiety. One method goes through the synthesis of intermediate compound eriodictyol followed by further de-oxygenation using NaBH3CN, while the second scheme involves the formation of o-quinone methide and the inverse electron-demand Diels-Alder reaction. The identities of synthesized kinkéloids were further confirmed through the comparison with the ones in the plant leaves extract using LC/MS. The enantiomers of each previous identified flavan molecules in the leaf samples were successfully separated on AD-RH column. A series of novel kinkéloids analogues were synthesized with different flavonoid aglycones and the attached nitrogen-containing moieties. The synthesized analogues were screened for the inhibitory activity of α- glucosidase, in which compound 23 has the lowest IC50 of 4.1 μM. Kinetic analysis indicates synthesized compounds 15 and 23 inhibit enzyme in a non-competitive model with Ki value of 37.8 ± 0.8 and 13.2 ± 0.6 μM. Further docking study suggests that the preferred binding pocket is close to the catalytic center, correlating to the experimental results very well. Structure activity relationship study indicates that 4’-hyroxyl group and the 4-position carbonyl group are important for the inhibitory activity. Addition of extra hydrogen bonding and hydrophobic groups on ring A may increase the inhibitory activity.
Subject (authority = RUETD)
Topic
Medicinal Chemistry
RelatedItem (type = host)
TitleInfo
Title
Rutgers University Electronic Theses and Dissertations
Identifier (type = RULIB)
ETD
Identifier
ETD_7668
PhysicalDescription
Form (authority = gmd)
electronic resource
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application/pdf
InternetMediaType
text/xml
Extent
1 online resource (xix, 231 p. : ill.)
Note (type = degree)
Ph.D.
Note (type = bibliography)
Includes bibliographical references
Subject (authority = ETD-LCSH)
Topic
Medicinal plants--Africa
Subject (authority = ETD-LCSH)
Topic
Roselle
Note (type = statement of responsibility)
by Jing Zhen
RelatedItem (type = host)
TitleInfo
Title
Graduate School - New Brunswick Electronic Theses and Dissertations
Identifier (type = local)
rucore19991600001
Location
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NjNbRU
Identifier (type = doi)
doi:10.7282/T3CN767B
Genre (authority = ExL-Esploro)
ETD doctoral
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The author owns the copyright to this work.
RightsHolder (type = personal)
Name
FamilyName
Zhen
GivenName
Jing
Role
Copyright Holder
RightsEvent
Type
Permission or license
DateTime (encoding = w3cdtf); (qualifier = exact); (point = start)
2016-09-28 13:53:07
AssociatedEntity
Name
Jing Zhen
Role
Copyright holder
Affiliation
Rutgers University. Graduate School - New Brunswick
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Author Agreement License
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I hereby grant to the Rutgers University Libraries and to my school the non-exclusive right to archive, reproduce and distribute my thesis or dissertation, in whole or in part, and/or my abstract, in whole or in part, in and from an electronic format, subject to the release date subsequently stipulated in this submittal form and approved by my school. I represent and stipulate that the thesis or dissertation and its abstract are my original work, that they do not infringe or violate any rights of others, and that I make these grants as the sole owner of the rights to my thesis or dissertation and its abstract. I represent that I have obtained written permissions, when necessary, from the owner(s) of each third party copyrighted matter to be included in my thesis or dissertation and will supply copies of such upon request by my school. I acknowledge that RU ETD and my school will not distribute my thesis or dissertation or its abstract if, in their reasonable judgment, they believe all such rights have not been secured. I acknowledge that I retain ownership rights to the copyright of my work. I also retain the right to use all or part of this thesis or dissertation in future works, such as articles or books.
RightsEvent
DateTime (encoding = w3cdtf); (qualifier = exact); (point = start)
2016-10-31
DateTime (encoding = w3cdtf); (qualifier = exact); (point = end)
2018-10-31
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Embargo
Detail
Access to this PDF has been restricted at the author's request. It will be publicly available after October 31st, 2018.
Copyright
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Copyright protected
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Status
Open
Reason
Permission or license
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2016-10-05T17:49:05
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2016-10-05T17:49:05
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