Date of Award

Spring 5-12-2018

Level of Access

Open-Access Dissertation

Language

English

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Advisor

Barbara J. W. Cole

Second Committee Member

Raymond C. Fort, Jr.

Third Committee Member

Bruce L. Jensen

Additional Committee Members

Brian Perkins

Angela Myracle

Abstract

Resveratrol is a plant secondary metabolite which protects plants from pathogenic invasions and acts as a remedial agent against injury, stress, and tissue damage by UV radiation. With its characteristic stilbene structure, resveratrol adopts (E) and (Z) isomeric forms. However, the (E) isomer is the most biologically active and abundant form of resveratrol in nature.

(E)- Resveratrol confers a variety of benefits to human health and well-being. Besides its antioxidant activity, the role of (E)-resveratrol as an anti-inflammatory, anti-aging, cardioprotection, and anticancer agent has been a widely explored research interest. Many plant species including mulberry, peanut, and grape are sources of the compound, while Japanese knotweed (Polygonum cuspidatum), an invasive herbaceous plant species, is currently the prime source for the commercial production of (E)-resveratrol.

Previous research findings of our group and other published work have shown that spruces native to Maine are rich sources of (E)-resveratrol, and the compound is located primarily in the bark of the trees. Bark is typically a waste material generated from the forest bioproducts industries in the state. Hence, development of a method to isolate (E)-resveratrol from Maine’s native conifer species would find a rewarding use for bark and open up industrial avenues that are highly relevant to the state of Maine. However, spruces inherently contain a variety of polyphenolic compounds with similar structural and functional properties. Hence the isolation of (E)-resveratrol from spruce bark extracts poses a challenging research problem.

In this study, a solvent extraction and column chromatography-based purification method was developed to isolate (E)-resveratrol from black spruce (Picea mariana) bark in high yield. Various chromatographic and other separation techniques have been explored in this work, and the concept of E-Z isomerization of resveratrol is discussed. Based on HPLC-MS and HPLC-UV analyses, the proposed purification method isolates the compound in 84% yield and 99% purity. The overall yield is 279.9 ± 4.9 µg (E)-resveratrol per dry gram of bark. Since the biosynthetic pathways of plants that produce a variety of polyphenolic compounds are related, it is anticipated that this purification method is applicable for isolating (E)-resveratrol from other plants as well.

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