Jan F. Stevens's research while affiliated with Oregon State University and other places

Publications (178)

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The slow pace of discovery of bioactive natural products can be attributed to the difficulty in rapidly identifying them in complex mixtures such as plant extracts. To overcome these hurdles, we explored the utility of two machine learning techniques, i.e., Elastic Net and Random Forests, for identifying the individual anti-inflammatory principle(s...
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Scope: Nitrate supplementation is a popular ergogenic aid that improves exercise performance by reducing oxygen consumption during exercise. We investigated the effect of nitrate exposure and exercise on metabolic pathways in zebrafish liver. Materials and methods: Fish were exposed to sodium nitrate (606.9 mg/L), or control water, for 21 days and...
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Phytochemicals from the genus, Fagonia, have been attracting increasing attention due to their potential beneficial effects on human health. Fagonia species contain various types of phytochemicals such as flavonoids, alkaloids, saponins, terpenoids, coumarins and tannins. In this study, we investigated the phytochemical composition of unhydrolyzed...
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Centella asiatica is reputed in Eastern medicine to improve cognitive function in humans. Preclinical studies have demonstrated that aqueous extracts of C. asiatica improve cognition in mouse models of aging and Alzheimer’s disease (AD) through the modulation of mitochondrial biogenesis and nuclear factor-erythroid-2-related factor 2 (Nrf2)-depende...
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Botanical products are frequently sold as dietary supplements and their use by the public is increasing in popularity. However, scientific evaluation of their medicinal benefits presents unique challenges due to their chemical complexity, inherent variability, and the involvement of multiple active components and biological targets. Translation awa...
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Due to an increase in the aging population, age-related diseases and age-related changes, such as diminished cognition and sleep disturbances, are an increasing health threat. It has been suggested that an increase in oxidative stress underlies many of these changes. Current treatments for these diseases and changes either have low efficacy or have...
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Marrubium friwaldskyanum Boiss (Lamiaceae) is a Bulgarian endemic species. Overall, the essential oil (EO) composition of M. friwaldskyanum was different from that of the other Marrubium species reported in the literature. The main EO constituents of M. friwaldskyanum were (E)-caryophyllene, germacrene D, and caryophyllene oxide. The effect of the...
Article
Background: Alzheimer's disease (AD) is a neurodegenerative disease characterized by the accumulation of amyloid-β (Aβ) peptide in the brain. Objective: Gain a better insight into alterations in major biochemical pathways underlying AD. Methods: We compared metabolomic profiles of hippocampal tissue of 20-month-old female Tg2576 mice expressin...
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Centella asiatica is an herb used in Ayurvedic and traditional Chinese medicine for its beneficial effects on brain health and cognition. Our group has previously shown that a water extract of Centella asiatica (CAW) elicits cognitive-enhancing effects in animal models of aging and Alzheimer’s disease, including a dose-related effect of CAW on memo...
Article
Polyphenols have attracted huge interest among researchers of various disciplines because of their numerous biological activities, such as antioxidative, antiinflammatory, antiapoptotic, cancer chemopreventive, anticarcinogenic, and antimicrobial properties, and their promising applications in many fields, mainly in the medical, cosmetics, dietary...
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Scope The polyphenol xanthohumol (XN) improves dysfunctional glucose and lipid metabolism in diet-induced obesity animal models. Because XN changes intestinal microbiota composition, we hypothesized that XN requires the microbiota to mediate its benefits. Methods and results To test our hypothesis, we fed conventional and germ-free male Swiss Webs...
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Isothiocyanates, such as sulforaphane and iberin, derived from glucosinolates (GLS) in cruciferous vegetables, are known to prevent and suppress cancer development. GLS can also be converted by bacteria to biologically inert nitriles, such as sulforaphane-nitrile (SFN-NIT) and iberin-nitrile (IBN-NIT), but the role of the gut microbiome in this pro...
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We previously reported xanthohumol (XN), and its synthetic derivative tetrahydro-XN (TXN), attenuates high-fat diet (HFD)-induced obesity and metabolic syndrome in C57Bl/6J mice. The objective of the current study was to determine the effect of XN and TXN on lipid accumulation in the liver. Non-supplemented mice were unable to adapt their caloric i...
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Objectives Dietary nitrate supplementation shows protective effects against cardio-metabolic disease, decreases pulmonary oxygen uptake, and improves exercise performance in animal models and humans. However, the biological effect of nitrate on energy metabolism in the liver is not well understood. The objective of this study was to elucidate chang...
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Objectives Dietary nitrate (NO3−) supplementation improves exercise performance by reducing the oxygen cost of exercise and enhancing skeletal muscle function. However, the mechanisms underlying the beneficial effects on exercise performance are not well understood and may be supported by changes in metabolism within the skeletal muscle. The purpos...
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Caffeoylquinic acids (CQAs) are specialized plant metabolites we encounter in our daily life. Humans consume CQAs in mg-to-gram quantities through dietary consumption of plant products. CQAs are considered beneficial for human health, mainly due to their anti-inflammatory and antioxidant properties. Recently, new biosynthetic pathways via a peroxid...
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Dietary nitrate supplementation improves exercise performance by reducing the oxygen cost of exercise and enhancing skeletal muscle function. However, the mechanisms underlying these effects are not well understood. The purpose of this study was to assess changes in skeletal muscle energy metabolism associated with exercise performance in a zebrafi...
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The farnesoid X receptor (FXR) plays a critical role in the regulation of lipid and bile acid (BA) homeostasis. Hepatic FXR loss results in lipid and BA accumulation, and progression from hepatic steatosis to nonalcoholic steatohepatitis (NASH). This study aimed to evaluate the effects of xanthohumol (XN), a hop-derived compound mitigating metaboli...
Preprint
We previously reported xanthohumol (XN), and its synthetic derivative tetrahydro-XN (TXN) attenuates high-fat diet (HFD) induced obesity and metabolic syndrome in C57BL/6J mice. The objective of the current study was to determine the effect of XN and TXN on lipid accumulation in the liver. Non-supplemented mice were unable to adapt their caloric in...
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Dietary nitrate lowers blood pressure and improves athletic performance in humans, yet data supporting observations that it may increase cerebral blood flow and improve cognitive performance are mixed. We tested the hypothesis that nitrate and nitrite treatment would improve indicators of learning and cognitive performance in a zebrafish ( Danio re...
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Centella asiatica (CA) is a botanical from Eastern medicine reputed to enhance cognition. Preclinical studies on CA and its bioactive components (triterpenoids and caffeoylquinic acids) strongly support its potential as a phytotherapeutic agent for aging, cognitive decline, and Alzheimer’s disease (AD) through influences on antioxidant response, mi...
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Centella asiatica (CA) is an edible plant and a popular botanical dietary supplement. It is reputed, in Ayurveda, to mitigate age-related cognitive decline. There is a considerable body of preclinical literature supporting CA’s ability to improve learning and memory. This study evaluated the contribution of CA’s triterpenes (TT), widely considered...
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Cardiac arrest (CA) is a leading cause of death and there is a necessity for animal models that accurately represent human injury severity. We evaluated a rat model of severe CA injury by comparing plasma metabolic alterations to human patients. Plasma was obtained from adult human control and CA patients post-resuscitation, and from male Sprague-D...
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Cardiac arrest (CA) is a leading cause of death and there is a necessity for animal models that accurately represent human injury severity. We evaluated a rat model of severe CA injury by comparing plasma metabolic alterations to human patients. Plasma was obtained from adult human control and CA patients post-resuscitation, and from male Sprague–D...
Preprint
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Introduction Dietary nitrate lowers blood pressure and improves athletic performance in humans, yet data supporting observations that it may increase cerebral blood flow and improve cognitive performance are mixed. Here we tested the hypothesis that nitrate and nitrite treatment would improve indicators of learning and cognitive performance in a ze...
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The coronavirus disease 2019 (COVID-19) is a public health emergency of international concern. The rising number of cases of this highly transmissible infection have stressed the urgent need to find a potent drug. Although repurposing of known drugs currently provides an accelerated route to approval, there is no satisfactory treatment. Polyphenols...
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Mol. Nutr. Food Res . 2020, 64 , 2000341 DOI: 10.1002/mnfr.202000341 Xanthohumol (XN), a flavonoid from hops (Humulus lupulus), and its hydrogenated derivatives, α,β‐dihydroxanthohumol (DXN) and tetrahydroxanthohumol (TXN) decrease hepatic cholesterol by enhancing de novo synthesis of bile acids and decrease ceramide content in liver and hippocampu...
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Scope Sphingolipids including ceramides are implicated in the pathogenesis of obesity and insulin resistance. Correspondingly, inhibition of pro‐inflammatory and neurotoxic ceramide accumulation prevents obesity‐mediated insulin resistance and cognitive impairment. Increasing evidence suggests the farnesoid X receptor (FXR) is involved in ceramide...
Article
Centella asiatica (CA) shows considerable promise for development as a botanical drug for cognitive decline. Its primary bioactive components include triterpene glycosides asiaticoside and madecassoside and their corresponding aglycones asiatic acid and madecassic acid. Exploration of the bioactivity of CA's caffeoylquinic acids is ongoing. In this...
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Objectives Dietary nitrate contributes to optimal cardiovascular health, exercise performance, and has been hypothesized to improve cognitive performance and affect cerebral blood flow in specific brain regions. While the mechanisms responsible are not fully understood, we tested the hypothesis that nitrate and nitrite treatment would improve indic...
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Objectives Whereas phytochemicals derived from cruciferous vegetables have demonstrated health benefits, the data linking intake of these vegetables to health outcomes are inconsistent. These inconsistencies may stem from methodological limitations in accurately assessing cruciferous vegetable exposure. Goals of this study were to explore the use o...
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Introduction The phytochemical composition of plant material governs the bioactivity and potential health benefits as well as the outcomes and reproducibility of laboratory studies and clinical trials. Objective The objective of this work was to develop an efficient method for the in‐depth characterisation of plant extracts and quantification of m...
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A calorie-dense diet is a well-established risk factor for obesity and metabolic syndrome (MetS), whereas the role of the intestinal microbiota (IMB) in the development of diet-induced obesity (DIO) is not completely understood. To test the hypothesis that Swiss Webster (Tac:SW) mice can develop characteristics of DIO and MetS in the absence of the...
Chapter
Humans are almost exclusively exposed to the prenylated hop chalcone, xanthohumol, by consumption of beer and hop-derived dietary supplements. Its spontaneous isomerization into the flavanone, isoxanthohumol, in conjunction with gut microbial and hepatic metabolism, produces several xanthohumol-derived prenylated flavonoids that exert bioactivities...
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Vitamin C (L-ascorbic acid, AA) is an essential cellular antioxidant and cofactor for several α-ketoglutarate-dependent dioxygenases. As an antioxidant, AA interacts with vitamin E to control oxidative stress. While several reports suggest an interaction of AA with folate (vitamin B9) in animals and humans, little is known about the nature of the i...
Article
Mol. Nutr. Food Res. 2020, 64, 1900789 DOI: 10.1002/mnfr.201900789 Hops‐derived xanthohumol (XN) and derivatives DXN and TXN reduce high‐fat diet (HFD)‐induced obesity and metabolic disorders in rodents. In article number 1900789, Adrian F. Gombart and co‐workers show that these compounds function as novel modulators of gut microbiota, reducing div...
Article
Scope: We previously showed that two hydrogenated xanthohumol (XN) derivatives, α,β-dihydro-XN (DXN) and tetrahydro-XN (TXN), improved parameters of metabolic syndrome (MetS), a critical risk factor of cardiovascular disease (CVD) and type 2 diabetes, in a diet-induced obese murine model. We hypothesized that improvements in obesity and MetS are l...
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In this study, an untargeted metabolomics approach was used to assess the effects of proton irradiation (1 Gy of 150 MeV) on the metabolome and DNA methylation pattern in the murine hippocampus and left ventricle of the heart 22 weeks following exposure using an integrated metabolomics-DNA methylation analysis. The integrated metabolomics-DNA methy...
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Background: Dietary nitrate improves exercise performance by reducing the oxygen cost of exercise, although the mechanisms responsible are not fully understood. Objectives: We tested the hypothesis that nitrate and nitrite treatment would lower the oxygen cost of exercise by improving mitochondrial function and stimulating changes in the availab...
Article
Background Cardiac arrest (CA) has been a leading cause of death for many decades. Despite years of research, we still do not understand how each organ responds to the reintroduction of blood flow after prolonged CA. Following changes in metabolites of individual organs after CA and resuscitation gives context to the efficiency and limitations of c...
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Xanthohumol (XN), a prenylated flavonoid found in hops, inhibits growth in a variety of cancer cell lines; however, its use raises concerns as gut microbiota and the host’s hepatic cytochrome P450 enzymes metabolize it into the most potent phytoestrogen known, 8-prenylnaringenin (8-PN). The XN derivatives dihydroxanthohumol (DXN) and tetrahydroxant...
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Mol. Nutr. Food Res. 2019, 63, 1800923 DOI: 10.1002/mnfr.201800923 Gut microbial metabolism of xanthohumol produces estrogenic metabolites, notably 8‐prenylnaringenin. In article number 1800923, Jan F. Stevens and co‐workers show that 8‐prenylnaringenin is not the end product of metabolism by gut microbes, shedding new light on the perceived pro‐es...
Article
Preparations of the root bark of Tabernanthe iboga have long been used in Central and West African traditional medicine to combat fatigue, as a neuro-stimulant in rituals, and for treatment of diabetes. The principal alkaloid of T. iboga, ibogaine, has attracted attention in many countries around the world for providing relief for opioid craving in...
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The role of epigenetic alterations during cancer has gained increasing attention and has resulted in a paradigm shift in our understanding of mechanisms leading to cancer susceptibility. Sulforaphane (SFN) is a naturally occurring isothiocyanate derived from the precursor glucosinolate, glucoraphanin (GFN), which is found in cruciferous vegetables...
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Exposure to ultraviolet B (UVB) irradiation of the skin leads to numerous dermatological concerns including skin cancer and accelerated aging. Natural product glucosinolate derivatives, like sulforaphane, have been shown to exhibit chemopreventive and photoprotective properties. In this study, we examined meadowfoam (Limnanthes alba) glucosinolate...
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It is commonly accepted that brain phospholipids are highly enriched with long-chain polyunsaturated fatty acids (PUFAs). However, the evidence for this remains unclear. We used HPLC–MS to analyze the content and composition of phospholipids in rat brain and compared it to the heart, kidney, and liver. Phospholipids typically contain one PUFA, such...
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This review describes in detail the phytochemistry and neurological effects of the medicinal herb Centella asiatica (L.) Urban. C. asiatica is a small perennial plant that grows in moist, tropical and sub-tropical regions throughout the world. Phytochemicals identified from C. asiatica to date include isoprenoids (sesquiterpenes, plant sterols, pen...
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Scope: Several lines of evidence suggest that the consumption of cruciferous vegetables is beneficial to human health. Yet, underlying mechanisms and key molecular targets that are involved with achieving these benefits in humans are still not fully understood. To accelerate this research, we conducted a human study to identify potential molecular...
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Xanthohumol (XN), a prenylated flavonoid from hops, improves dysfunctional glucose and lipid metabolism in animal models of metabolic syndrome (MetS). However, its metabolic transformation into the estrogenic metabolite, 8-prenylnaringenin (8-PN), poses a potential health concern for its use in humans. To address this concern, we evaluated two hydr...
Article
Scope: Xanthohumol (XN), a prenylated flavonoid found in hops, exhibits anti-inflammatory and antioxidant properties. However, poor bioavailability may limit therapeutic applications. As food components are known to modulate polyphenol absorption, the objective was to determine whether a protein matrix could enhance the bioavailability of XN post...
Article
Significance: Humans are exposed daily to polyphenols in milligram-to-gram amounts through dietary consumption of fruits and vegetables. Polyphenols are also available as components of dietary supplements for improving general health. Although polyphenols are often advertised as antioxidants to explain health benefits, experimental evidence shows...
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Abstract Xanthohumol [(E)-6´-methoxy-3´-(3-methylbuten-2-yl)-2´,4´,4´´-trihydroxychalcone], the principal prenylated flavonoid from hops, has a complex bioactivity profile and 13C-labelled isotopomers of this compound are of potential use as molecular probes and as analytical standards to study metabolism and mode-of-action. 1,3-[13C]2-Xanthohumol...
Article
Buprenorphine is a partial μ-opioid agonist used for analgesia. Due to the small size of laboratory rodents, buprenorphine HCl is typically diluted 10- or 20-fold with a sterile diluent, such as saline, for accurate dosing. Protocols for preparing and storing diluted buprenorphine vary by institution, and little published information is available r...
Article
Buprenorphine is a partial μ-opioid agonist used for analgesia. Due to the small size of laboratory rodents, buprenorphineHCl is typically diluted 10- or 20-fold with a sterile diluent, such as saline, for accurate dosing. Protocols for preparing andstoring diluted buprenorphine vary by institution, and little published information is available reg...