Katherine Stephenson

Ms. Katherine Stephenson


Research Focus & Metrics

Academic Career Length

14Years (2013-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 May 2013 in Biochemical and Biophysical Research Communications
Verified
Journal Article
Closed access
JFJed W. Fahey
Jed W. Fahey
KSKatherine Stephenson
Katherine Stephenson
KWKristina Wade
Kristina Wade
PTPaul Talalay
Paul Talalay

29 June 2019 in Nutrients
Verified
Journal Article
Open access
PDF file
JFJed W. Fahey
Jed W. Fahey
KWKristina Wade
Kristina Wade
KSKatherine Stephenson
Katherine Stephenson
APAnita Panjwani
Anita Panjwani
HLHua Liu
Hua Liu
LCLawrence Cheskin
Lawrence Cheskin
We examined whether gastric acidity would affect the activity of myrosinase, co-delivered with glucoraphanin (GR), to convert GR to sulforaphane (SF). A broccoli seed and sprout extract (BSE) rich in GR and active myrosinase was delivered before and after participants began taking the anti-acid omeprazole, a potent proton pump inhibitor. Gastric acidity appears to attenuate GR bioavailability, as evidenced by more SF and its metabolites being excreted after participants started taking omeprazole. Enteric coating enhanced conversion of GR to SF, perhaps by sparing myrosinase from the acidity of the stomach. There were negligible effects of age, sex, ethnicity, BMI, vegetable consumption, and bowel movement frequency and quality. Greater body mass correlated with reduced conversion efficiency. Changes in the expression of 20 genes in peripheral blood mononuclear cells were evaluated as possible pharmacodynamic indicators. When grouped by their primary functions based on a priori knowledge, expression of genes associated with inflammation decreased non-significantly, and those genes associated with cytoprotection, detoxification and antioxidant functions increased significantly with bioavailability. Using principal components analysis, component loadings of the changes in gene expression confirmed these groupings in a sensitivity analysis.

9 July 2019 in Nutrients
Verified
Journal Article
Open access
PDF file
JFJed W. Fahey
Jed W. Fahey
KWKristina Wade
Kristina Wade
KSKatherine Stephenson
Katherine Stephenson
YSYuzhu Shi
Yuzhu Shi
HLHua Liu
Hua Liu
MOMark E. Olson
Mark E. Olson
The tropical tree Moringa oleifera produces high yields of protein-rich leaf biomass, is widely used as a food source, contains an abundance of phytochemicals, and thus has great potential for chronic disease prevention and perhaps, treatment. We have developed and characterized standardized ways of preparing aqueous “teas” from moringa leaves to deliver precisely calibrated levels of phytochemicals for use in clinical trials. These phytochemicals, especially the glucosinolate glucomoringin and the isothiocyanate moringin, produced from it following hydrolysis by the enzyme myrosinase, provide potent anti-inflammatory and cytoprotective indirect antioxidant activity. The taste of both hot and cold teas is palatable without the need for flavor masking. These teas can be easily and reproducibly prepared in underserved tropical regions of the world where moringa is cultivated. Isothiocyanate yield from a cold extraction was rapid and essentially complete after 30 min and its anti-inflammatory potential is comparable to that of equimolar purified moringin. A preparation similar to this may be safe to consume with respect to its bacterial titer even after 48 h without refrigeration. Thus, facile delivery of moringa tea to both adults and children for clinical evaluation of their effects on such conditions as autism, diabetes, and hypertension, is now possible.

29 May 2025 in Metabolites
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Journal Article
Open access
PDF file
ACAnna L. Chien
Anna L. Chien
HLHua Liu
Hua Liu
SRSaleh Rachidi
Saleh Rachidi
JFJessica L. Feig
Jessica L. Feig
RWRuizhi Wang
Ruizhi Wang
SKSewon Kang
Sewon Kang
Background/Objectives: Oxidative stress plays a pivotal role in skin aging and carcinogenesis. Phytochemicals such as sulforaphane (SF, from broccoli sprouts or seeds) or curcumin (CUR, from turmeric) can be highly protective against this stress. They each induce a suite of cytoprotective and antioxidant enzymes that are coordinately transcribed via the Keap1-Nrf2-ARE pathway in mammals, such as the prototypical cytoprotective enzyme NAD(P)H dehydrogenase 1 (NQO1). Methods: Eighteen healthy human volunteers (9 males, 9 females, aged 18–69. were randomized to receive daily glucoraphanin (GR), which is converted to SF upon ingestion (450 mg; 1 mmol), CUR (1000 mg; 2.7 mmol), or both (450 mg GR + 1000 mg CUR), as oral supplements. After 8 days of a diet low in both compounds, blood and urine were collected for compliance and biomarker measurements. Randomized spots on the buttock’s skin were exposed to 2 x M.E.D. of UVB, and punch biopsies were obtained 1 and 3 days later for biomarker and histological measurement. Erythema was measured with a chromameter daily for 3 consecutive days following UVB. The process was repeated after receiving oral supplements, both with and without UVB exposure. Results: Compared to baseline, each treatment (n = 6 for each) induced NQO1 mRNA levels in skin biopsies: 3.1-fold with GR, 3.3-fold with CUR, and 3.6-fold with the combination of GR and CUR. Across all treatments (n = 18), expression of the pro-inflammatory cytokines IL-1β and TNF-α were reduced, as were IL-6, IL-17, STING, and CYR61, though less robustly. Modulation of these biomarkers persisted, but was less pronounced, in biopsies taken following UV exposure. The presence of SF and its metabolites in the skin post-treatment was confirmed by examining 6 of 12 subjects who ingested GR. Supplement effects on erythema following UV exposure were not significant, and no significant changes were measured in the same biomarkers in blood cells (PBMC), or by counting dyskeratotic keratinocytes. Supplements were well tolerated and compliance was excellent. Conclusions: Oral GR and CUR are well tolerated and have for the first time been shown to result in increased expression of cytoprotective genes and reduced expression of inflammatory cytokine genes in human skin in vivo. This mechanism-based clinical study suggests that an antioxidant, anti-inflammatory, and cytoprotective benefit from these oral supplements is delivered to the skin in humans.

23 October 2025 in Applied Sciences
Verified
Journal Article
Open access
PDF file
JFJed W. Fahey
Jed W. Fahey
KWKristina Wade
Kristina Wade
KSKatherine Stephenson
Katherine Stephenson
HLHua Liu
Hua Liu
The naphthazarins shikonin and alkannan are strongly chromogenic, dark red enantiomers, each of which has biological activity, that are found primarily in the plant family Boraginaceae. These compounds and their many chemical metabolites, derivatives, oligomers, and analogs (“shikonoids”) are an important group of phytochemicals, utilized since antiquity as components of dyes, traditional medicines, and food and cosmetics. They are now recognized for their potent anti-inflammatory and regulatory activity on a variety of molecular signaling pathways in humans. Since many Boraginaceae species are overly exploited or endangered, we developed a pilot-scale in vitro shikonoid production system using Plagiobothrys arizonicus (Gray) Greene ex A.Gray, the Arizona popcorn flower, native to the southwestern USA and the Sonoran floristic province in the Madrean region of Mexico. Aseptic root cultures were initiated from fresh leaf tissue and stimulated to continuously produce shikonoids in liquid shake cultures layered under paraffin oil from which the shikonoids were extracted and concentrated. The crude, red extracellular product from these rapidly expanding root masses was also fractionated by Centrifugal Counter-Current Chromatography (CCC) into its component shikonin derivatives. A number of these shikonoids profoundly up-regulated detoxification and antioxidant proteins (phase 2 enzymes) and inhibited inflammation in mammalian cell bioassay systems. This prototype shikonoid production methodology can be readily scaled to either batch or chemostat culture.