Date of Award

Spring 5-8-2020

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Food Science and Human Nutrition

Advisor

L. Brian Perkins

Second Committee Member

Rodney Bushway

Third Committee Member

Angela Myracle

Additional Committee Members

Karl Bishop

Balukeswar Nayak

Abstract

Inonotus obliquus, commonly known as Chaga, is a fungal pathogen of birch trees, known to synthesize a range of phenolic compounds with remarkable health benefits. These presumed medicinal properties have generated increased interest in Chaga consumption. Prior research has demonstrated the diverse chemical composition of Chaga sourced from a variety of geographical locations. However, to our knowledge, there is currently no available literature regarding the extraction of bioactive compounds from Chaga grown in the United States. Additionally, the effect of the extraction method on the antioxidant and anti-inflammation properties specifically, has yet to be validated. Therefore, the present study was developed to examine the effects of extraction conditions on phenolic compounds in Maine sourced Chaga and correlate these findings to anti-inflammatory benefits. A high-performance liquid chromatography–diode array detection (HPLC–DAD) method was developed to determine the phenolic acids content in Chaga. The method demonstrated good linearity (0.994-0.999) and precision within (RSD ≤ 3) and between (RSD ≤ 4.2) -day precisions. The procedure also produced good recovery within (≥ 90.1) and between (≥88.5) -day precisions, as well. The majority of phenolic acids were extracted from the base hydrolysis fraction (2794.91 μg/g). The response surface methodology (RSM) was also applied to establish optimum extraction conditions to obtain phenolic-rich extracts. Results indicate that an extraction temperature of 170°C and ethanol concentration of 66% were optimal for recovering phenolic compounds, with a total phenolic content (TPC) value of 39.32 mg GAL/g DW and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of 76.59%. The extractions that produced the highest yields of TPC and DPPH were then assessed for the ability to remediate inflammation using lipopolysaccharide (LPS) activated RAW 264.7 macrophages. The results showed various Chaga extracts have significant antiinflammatory activity on LPS-stimulated RAW 264.7 cells. The inhibitory effect was evident through a decrease in the production of nitric oxide (NO) and down-regulation of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-β (IL-1β) in RAW 264.7 macrophages. Therefore, findings confirm that Maine harvested Chaga demonstrates anti-inflammatory properties. However, the phenolic yields (total phenolic acids and TPC) and antioxidant activity are highly dependent upon the extraction methodology.

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