Our daily bread has more benefits than we thought - C&EN Global

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NATURAL PRODUCTS

▸ Our daily bread has more benefits than we thought Whole grains in bread and other foods can add a healthy dose of vitamins, minerals, protein, and fiber to our diets. But scientists such as Inge S. Fomsgaard of Aarhus University are looking further at how some lesser-known bioactive grain compounds called benzoxazinoids, or BXs for short, can improve health through their immune-boosting properties. Scientists have known for a few decades that BXs help protect young cereal grain plants such as rye, wheat, and corn against weeds, insects, and diseases. But it wasn’t until 2009 that Fomsgaard’s group discovered that mature grains also contain BXs. Fomsgaard and her colleagues subsequently found that BXs survive food processing and that the composition and concentration of the compounds are enhanced

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CREDIT: ALDO LOBOS (FUNGI); INGE FOMSGAARD (BREAD); IYER LAB (COLLAGEN)

Fomsgaard and her coworkers prepared this set of rye breads using new recipes to enhance the content of healthful benzoxazinoid compounds. via enzymatic processes during malting or baking. Using mass-spectrometry-based metabolomics methods in rats, pigs, and people, the researchers have shown that BXs are taken up, distributed, and metabolized by mammals and that a diet high in BXs provides a boost to immune cells. Fomsgaard created the Bread & Breakfast project to take advantage of the compounds, including developing new food products with optimized BX content. The team also initiated the RyeproC project after experiments in mice and humans by other groups showed that rye bran helps suppress prostate cancer. In initial studies, the Aarhus team has uncovered seven BXs that enter prostate tissue, with HBOA-glc being the major metabolite detected.—STEVE RITTER

University of South Florida researchers want to see if these three fungi, Aspergillus niger (left), Penicillium simplicissimum (middle), and Penicillium chrysogenum (right), can recycle lithium-ion battery metals.

ENVIRONMENT

Recycling batteries with fungi Typical lithium-ion battery recycling methods, such as smelting and acid leaching, have significant disadvantages: Smelting is a high-temperature, energy-intensive process, and both processes generate harmful waste. At the ACS national meeting last week, Jeffrey A. Cunningham of the University of South Florida proposed a greener way to recycle involving fungi. The idea is to promote growth of fungal colonies on pulverized batteries. As these microbes grow, they produce organic acids that would then help leach out the valuable metals from the batteries, making the metals easy to isolate for further processing. Cunningham and his team have identified conditions for quickly growing three candidate strains of fungi, analyzed the organic acids they generate as they multiply, and evaluated the effectiveness of commercial versions of those acids in leaching battery metals. Oxalic acid and citric acid, which are less harsh than common mineral acids, can extract up to 85% of the lithium and nearly half of the cobalt from cathodes of spent batteries. Now, the team plans to study the effectiveness of the fungi-produced versions of the acids, determine how well the fungi tolerate the extracted metals, and evaluate the economic viability of using fungi to recycle battery metals.—MITCH JACOBY

DRUG DISCOVERY

▸ Enzyme inhibitors help reverse scars Few treatments are currently available to reduce scarring, which can be unsightly and can restrict movement. Researchers are now trying to develop a therapeutic agent that can reverse scarring of skin that was previously injured. Priyanka Toshniwal, a graduate student in Swaminathan Iyer’s group at the University of Western Australia, presented a poster on the work at the ACS national meeting last week. The UWA researchers—in collaboration with colleagues at the Fiona Wood Foundation, Royal Perth Hospital Burns Unit, and Pharmaxis, all in Australia—are studying compounds that inhibit the enzyme lysyl oxidase. When skin becomes damaged, lysyl oxidase catalyzes cross-linking of the protein collagen, forming scars that close the wound. Imaging and biochemical tests on human cells treated with lysyl oxidase inhibitors showed that the agents reduce collagen cross-linking,

This image shows cross-linked collagen (green) in cells from a patient with Dupuytren’s contracture, a hand deformity that involves scar tissue. which could make skin look more normal. The researchers are now studying the efficacy of inhibitors in animal models and hope to start human trials of topical nanoformulations in a few years. Those who could benefit from such treatments include patients with burns, raised scars called keloids, and a hand deformity called Dupuytren’s contracture, the researchers say.—STU BORMAN AUGUST 29, 2016 | CEN.ACS.ORG | C&EN

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Science Concentrates: ACS meeting news DIAGNOSTICS

MATERIALS

A simple strategy for detecting tuberculosis

Hydrogel promises painless bandage removal

Tuberculosis afflicts more than 9 million people annually, according to the World Health Organization. A key step to keeping TB in check is to detect and monitor the disease to ensure patients aren’t developing resistance to their medication. In wealthy areas, this is done with chest X-rays and advanced lab tests. In resource-strapped regions, where TB can be common, pa-

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OH 4-DMN-trehalose tients are typically diagnosed with the Ziehl-Neelsen test—an 11-step saliva screening that dates back to the 1880s. Now, researchers led by Stanford University’s Carolyn Bertozzi report they can diagnose TB with a simpler procedure. The new test relies on a dye called 4-N,N-dimethylamino1,8-naphthalimide, or 4-DMN. This dye changes color in response to its surroundings: It’s colorless in aqueous solutions but glows green in hydrophobic environments. Bertozzi’s group covalently linked 4-DMN to the disaccharide trehalose. An enzyme in Mycobacterium tuberculosis adds a long fatty acid chain to the 4-DMN-trehalose molecule, which then becomes integrated into the microorganism’s hydrophobic membrane, where it glows. Because the bacterium must be alive to metabolize the molecule, the new procedure doesn’t detect dead cells, making it a good point-of-care test for following TB’s progress. The diagnostic procedure, Bertozzi said, is very simple: A solution of 4-DMN-trehalose is combined with a saliva sample, incubated for about an hour, and then observed with a microscope. “We don’t even have to wash it,” she noted. The compound is currently being field-tested in South Africa in collaboration with Bavesh Kana of the University of the Witwatersrand.—BETHANY HALFORD

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C&EN | CEN.ACS.ORG | AUGUST 29, 2016

When doctors need to change the dressing on a severe second-degree burn, they often have to pull off the bandage and scrape the wound to remove any dead tissue. Because the nerves are still active in second-degree burns, removing the bandage can be so painful that children who are burn victims are often anesthetized to make the dressing changes less traumatic. Boston University chemistry professor Mark W. Grinstaff and colleagues have now come up with a gel-like dressing material that dissolves on demand with the simple addition of a thiol. When the researchers spray the material with a solution of cysteine methyl ester, the thiol breaks down the cross-linked material Hydrogel treated with Branched polymer by severing its thioester linkages. cysteine methyl ester hydrogel Grinstaff’s team, which included Marlena D. Konieczynska of A branched polymer hydrogel Boston University and Juan C. developed as a burn dressing Villa-Camacho of Beth Israel dissolves in the presence of cysteine Deaconess Medical Center, testmethyl ester. ed the hydrogel dressing on rats with second-degree burns. Not only did the bandages seal the rats’ wounds, Konieczynska reported at the ACS national meeting, they also kept out bacteria that the researchers applied on top of the dressed burn (Angew. Chem. Int. Ed. 2016, DOI: 10.1002/anie.201604827). This is important because infections are a major cause of death in burn patients. Grinstaff hopes to test the hydrogel burn dressings on patients within the next 12 to 18 months.—BETHANY HALFORD

FLUORINATION

stead of a pyridine, enabling development of a new PET tracer for brain imaging. The electron-withdrawing nature of the N-oxide group alters the ring electron density enough to enable nucleophilic substitution of a meta halogen with a fluoride quickly at Developing new positron emission toroom temperature, Brugarolas explained. mography (PET) tracers for biomedical After fluorination, the chemists reduce the imaging is one of the hottest areas of fluoN-oxide group via palladium-catalyzed hyrine chemistry, and one of the most chaldrogenation to generate the pyridine (Chem. lenging. For example, using nucleophilic Commun. 2016, DOI: 10.1039/c6cc02362b). fluorination to develop meta-substituted The end product, 3-fluoro-4-aminopypyridines that can be used as tracers is ridine, is an analog of the multiple scledifficult because the aromatic ring is too rosis drug 4-aminopyridine, which is a electron-rich. Postdoctoral researcher Pepotassium ion channel blocker that helps dro Brugarolas of the University of Chicaimprove neuronal function in people with go and his colleagues have overcome this MS. Working with University of Chicago challenge by starting with an N-oxide inneuroscientist Brian Popko, Brugarolas is testing the – – O O new tracer by + N imaging brain N+ N TBA-18F H2/Pd lesions nonin25 ºC, 15 min. 18F vasively in ro18F 25 ºC, 15 min. Br dents.—STEVE NH

▸ Fluorinated pyridine offers new PET tracer

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CREDIT: ANGEW. CHEM. INT. ED.

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