Kristina L. Wade

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.

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.

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.

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.

Scope: The isothiocyanate sulforaphane (SF) from broccoli is one of the most potent known inducers of the cytoprotective phase 2 response. Its role in a host of biochemical pathways makes it a major component of plant‐based protective strategies for enhancing healthspan. Many nutritional supplements are now marketed that purport to contain SF, which in plants exists as a stable precursor, a thioglucoside hydroxysulfate. However, SF in pure form must be stabilized for use in supplements.Methods and results: We evaluated the stability and bioavailability of two stabilized SF preparations—an α‐cyclodextrin inclusion (SF‐αCD), and an SF‐rich, commercial nutritional supplement. SF‐αCD area‐under‐the‐curve peak serum concentrations occurred at 2 h, but six of ten volunteers complained of mild stomach upset. After topical application it was not effective in upregulating cytoprotective enzymes in the skin of SKH1 mice whereas pure SF was effective in doing so. Both of these “stabilized” SF preparations were as potent as pure SF in inducing the cytoprotective response in cultured cells, and they were more stable and as bioavailable.Conclusion: Our studies of a stabilized phytochemical component of foods should encourage further examination of similar products for their utility in chronic disease prevention and therapy.

Glucoraphanin from broccoli and its sprouts and seeds is a water soluble and relatively inert precursor of sulforaphane, the reactive isothiocyanate that potently inhibits neoplastic cellular processes and prevents a number of disease states. Sulforaphane is difficult to deliver in an enriched and stable form for purposes of direct human consumption. We have focused upon evaluating the bioavailability of sulforaphane, either by direct administration of glucoraphanin (a glucosinolate, or β-thioglucoside-N-hydroxysulfate), or by co-administering glucoraphanin and the enzyme myrosinase to catalyze its conversion to sulforaphane at economic, reproducible and sustainable yields. We show that following administration of glucoraphanin in a commercially prepared dietary supplement to a small number of human volunteers, the volunteers had equivalent output of sulforaphane metabolites in their urine to that which they produced when given an equimolar dose of glucoraphanin in a simple boiled and lyophilized extract of broccoli sprouts. Furthermore, when either broccoli sprouts or seeds are administered directly to subjects without prior extraction and consequent inactivation of endogenous myrosinase, regardless of the delivery matrix or dose, the sulforaphane in those preparations is 3- to 4-fold more bioavailable than sulforaphane from glucoraphanin delivered without active plant myrosinase. These data expand upon earlier reports of inter- and intra-individual variability, when glucoraphanin was delivered in either teas, juices, or gelatin capsules, and they confirm that a variety of delivery matrices may be equally suitable for glucoraphanin supplementation (e.g. fruit juices, water, or various types of capsules and tablets).

Introduction: Myrosinase (thioglucoside glucohydrolase; E.C. 3.2.1.147), is a plant enzyme of increasing interest and importance to the biomedical community. Myrosinase catalyses the formation of isothiocyanates such as sulforaphane (from broccoli) and 4‐(α‐l‐rhamnopyranosyloxy)benzyl isothiocyanate (from moringa), which are potent inducers of the cytoprotective phase‐2 response in humans, by hydrolysis of their abundant glucosinolate (β‐thioglucoside N‐hydroxysulphate) precursors.Objective: To develop an aqueous two‐phase counter‐current chromatography (CCC) system for the rapid, three‐step purification of catalytically active myrosinase.Methods: A high‐concentration potassium phosphate and polyethylene glycol biphasic aqueous two‐phase system (ATPS) is used with a newly developed CCC configuration that utilises spiral‐wound, flat‐twisted tubing (with an ovoid cross‐section).Results: Making the initial crude plant extract directly in the ATPS and injecting only the lower phase permitted highly selective partitioning of the myrosinase complex before a short chromatography on a spiral disk CCC. Optimum phase retention and separation of myrosinase from other plant proteins afforded a 60‐fold purification.Conclusion: Catalytically active myrosinase is purified from 3‐day broccoli sprouts, 7‐day daikon sprouts, mustard seeds and the leaves of field‐grown moringa trees, in a CCC system that is predictably scalable. Copyright © 2014 John Wiley & Sons, Ltd.

Flavonoids are secondary plant products that are well represented in healthy diets because of ingestion of fruit, vegetables, herbs, and teas. Increased consumption is correlated with decreased risks of cardiovascular disease, cancer, and other chronic diseases. Certain flavonoids confer direct antioxidant protection to cells, others induce enzymes that protect cells against oxidative and other insults (“indirect antioxidants”), and others appear to be protective by both mechanisms. Hydroxylated flavones manifest substantial direct antioxidant activity but do not effectively induce cytoprotective enzymes. Methoxylated flavones that potently induce cytoprotective enzymes were evaluated to elucidate the structural prerequisites for effective chemoprotective agents: protecting healthy cells with minimal collateral toxicity. Flavones and flavanones methoxylated at the 5-position of the A-ring were among the most potent inducers of the cytoprotective NAD(P)H:quinone-oxidoreductase 1 (NQO1) in 3 different cell lines. Other flavones were equally potent inducers, but more toxic. Flavanones contain no Michael reaction center, yet some are potent inducers of NQO1, have low cytotoxicity, and inhibit LPS-stimulated iNOS activity, which suggests a redox mechanism of action rather than the Keap1/Nrf2/ARE mechanism by which so many of the classic inducers operate. Evaluation in vivo will reveal whether differential protective advantages support their possible evaluation in a cancer prevention setting.

Allyl isothiocyanate (AITC), which occurs in many common cruciferous vegetables, was recently shown to be selectively delivered to bladder cancer tissues through urinary excretion and to inhibit bladder cancer development in rats. The present investigation was designed to test the hypothesis that AITC-containing cruciferous vegetables also inhibit bladder cancer development. We focused on an AITC-rich mustard seed powder (MSP-1). AITC was stably stored as its glucosinolate precursor (sinigrin) in MSP-1. Upon addition of water, however, sinigrin was readily hydrolyzed by the accompanying endogenous myrosinase. This myrosinase was also required for full conversion of sinigrin to AITC in vivo , but the matrix of MSP-1 had no effect on AITC bioavailability. Sinigrin itself was not bioactive, whereas hydrated MSP-1 caused apoptosis and G ₂ /M phase arrest in bladder cancer cell lines in vitro . Comparison between hydrated MSP-1 and pure sinigrin with added myrosinase suggested that the anticancer effect of MSP-1 was derived principally, if not entirely, from the AITC generated from sinigrin. In an orthotopic rat bladder cancer model, oral MSP-1 at 71.5 mg/kg (sinigrin dose of 9 μmol/kg) inhibited bladder cancer growth by 34.5% ( P < 0.05) and blocked muscle invasion by 100%. Moreover, the anticancer activity was associated with significant modulation of key cancer therapeutic targets, including vascular endothelial growth factor, cyclin B1 and caspase 3. On an equimolar basis, the anticancer activity of AITC delivered as MSP-1 appears to be more robust than that of pure AITC. MSP-1 is thus an attractive delivery vehicle for AITC and it strongly inhibits bladder cancer development and progression.