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Chemical And Microbial Ecology Of ‘Awa, Piper Methysticum (G. Forst)

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Title:Chemical And Microbial Ecology Of ‘Awa, Piper Methysticum (G. Forst)
Authors:Showman, Angelique
Contributors:Molecular Biosciences & Bioeng (department)
Date Issued:May 2017
Publisher:University of Hawaiʻi at Mānoa
Abstract:Kava or ‘Awa, Piper methysticum (G. Forst), is traditionally a social, medical and ceremonial
drink used in Hawai‘i, across the Pacific, and more recently, as a nutraceutical primarily for the
treatment of anxiety. This thesis documents two distinct yet related projects on kava biology:
(1) Identification of physiological effects of kava exposure in cells of the immune system.
Rationale: The efficacy and possible toxicity of kava may reflect additional biological targets in
addition to GABA receptors in the CNS. Hypothesis: Immune system cells and their calcium
signaling channels (e.g. the TRP family that have been shown to react to plant secondary
metabolites from diverse sources) may be novel targets for kava constituents. If validated, this
hypothesis would illuminate new understandings of the therapeutic potential of kava, as well as
the indigenous medicine indications of the drink. Results: Using whole cell patch clamping
techniques, bulk cell calcium and single cell calcium assays and on the RBL2H3 cell model, we
demonstrated that kava, as well as non-kava lactone components separated via reversed-phase
HPLC, were active on these non-CNS cellular targets. Specifically, whole cell patch clamping
revealed TRPV1-like, TRPM2-like and ICRAC-like conductances. Bulk calcium assays showed at
minimum that some non-kava lactone fractions initiated a minor release of both internal and
external calcium stores, which was confirmed by single cell calcium assays indicating a
significant difference (p < 0.01) was observed. We further characterized calcium responses
demonstrated by non-fractioned kava extractions via calcium-stored depletion using thapsigargin,
a known ICRAC inductor, and calcium add-back experiments and learned that kava is able to
enhance calcium influx responses above those initiated via ICRAC depletion indicating that non-
CRAC channels are being recruited and are not-overlapping. Conclusions: These results suggest
that a diverse secondary metabolome in kava is likely to affect the physiological and
pathophysiological response in cells via compounds other than kavalactones and via targets other
than GABA-R. Future studies would focus upon identification by fractionation of the individual
secondary metabolites that are regulating human immune cell calcium signaling pathways.
(2) Pilot evaluation of the kava plant associated microbiome. Rationale: Production of these
secondary metabolites that regulate human physiology are heavily affected by changes in the
physical and biological environment of the whole plant, including the plant’s associated
microbial community. The first step towards assessing this impact on kava is to define the soil
and plant microbiome, so we present the first known kava microbiome study. Hypothesis: The
kava plant associated microbiome is different between cultivars and differs from surrounding
bulk soil. If validated, this hypothesis would form the basis for more extensive studies to assess
the impact of associate microbiome on kava secondary metabolism. Results: We compared the
microbial communities associated with two kava strains (Hanakapi‘ai and Papa ‘ele ‘ele) and
surrounding bulk soil. In addition, since washing of the roots is a key preparative step for
indigenous kava users, we assessed the impact of this practice on the microbial community
associated with roots of the Papa kea kava strain. Conclusions: Significant differences were
observed between bulk soil and strains, but more importantly, significant differences in the
microbiome between strains were determined. Future studies would focus on larger sample sets
and replicate samples to archive statistically significant and robust differences, however, these
data do indicate that cultivars indeed select their microbial ecology and root washing affects the
Description:M.S. Thesis. University of Hawaiʻi at Mānoa 2017.
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: M.S. - Molecular Biosciences and Bioengineering

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