John A. Manthey

Biological Properties of Flavonoids Pertaining to Inflammation

Chronic venous insufficiency (CVI) is accompanied by a marked inflammatory response that is thought to contribute to the development and progression of the disorder. While compression therapy has long been considered the standard treatment for CVI, recent studies suggest that treatment with flavonoids may also be beneficial. The purpose of this review is to summarize how plant flavonoids attenuate inflammation and the immune response through their inhibition of important regulatory enzymes. Certain flavonoids are potent inhibitors of the production of prostaglandins, a group of powerful proinflammatory signaling molecules. Studies have shown that this effect is due to flavonoid inhibition of key enzymes involved in prostaglandin biosynthesis (i.e., lipoxygenase, phospholipase, and cyclooxygenase). Flavonoids also inhibit phosphodiesterases involved in cell activation. Much of this effect is upon the biosynthesis of protein cytokines that mediate adhesion of circulating leukocytes to sites of injury. The protein kinases are another class of regulatory enzymes affected by flavonoids. The inhibition of kinases is due to the competitive binding of flavonoids with ATP at catalytic sites on the enzymes. These modes of inhibition provide the mechanisms by which flavonoids inhibit the inflammation response and suggest that this class of molecules may be effective in the treatment of CVI.

Regulation of Lipoprotein Metabolism in HepG2 Cells by Citrus Flavonoids

Elevated levels of blood cholesterol are known to be one of the major risk factors associated with coronary heart disease (CHD), the leading cause of death in North America. The association is largely due to the importance of cholesterol, especially low-density lipoprotein (LDL) cholesterol, in the formation and development of atherosclerotic plaque, the underlying pathological condition of CHD. Dietary intervention has been proven to play an important role in prevention and treatment of hypercholesterolemia. Common dietary strategies aimed to lower high blood cholesterol include reduced intake of dietary saturated fat and cholesterol and increased intake of fiber (Connor and Connor, 1998). Recently, many reports have proposed another approach: increased intake of certain food components and food products with cholesterol-lowering potential (Cook and Samman, 1996).

Leaf and root responses to iron deficiency in avocado 1

Abstract Physiological responses to iron (Fe) deficiency were characterized in the roots and leaves of avocado plants. These responses included sharply higher catecholase activity, but slightly lower peroxidase activity in leaves and roots of avocado seedlings grown in minus Fe nutrient solutions, and in Fe‐deficient leaves of field trees. Iron deficiency in avocado seedlings resulted in much higher rates of MTT [3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide] reduction on the root surfaces. Similarly, the initial rates of FeHEDTA reduction were greater for roots of Fe‐deficient avocado seedlings. In contrast, root respiration rates were relatively unaffected by Fe deficiency. Large differences in the manganese (Mn) and zinc (Zn) concentrations in the leaves of the Fe‐deficient and Fe‐sufficient avocado seedlings suggested that the physiological responses that occurred in the roots during Fe deficiency influenced the uptake of other metal micronutrients.

Aspergillus niger metabolism of citrus furanocoumarin inhibitors of human cytochrome P450 3A4

Fungi metabolize polycyclic aromatic hydrocarbons by a number of detoxification processes, including the formation of sulfated and glycosidated conjugates. A class of aromatic compounds in grapefruit is the furanocoumarins (FCs), and their metabolism in humans is centrally involved in the “grapefruit/drug interactions.” Thus far, the metabolism by fungi of the major FCs in grapefruit, including 6′, 7′-epoxybergamottin (EB), 6′, 7′-dihydroxybergamottin (DHB), and bergamottin (BM), has received little attention. In this study, Aspergillus niger was observed to convert EB into DHB and a novel water-soluble metabolite (WSM). Bergaptol (BT) and BM were also metabolized by A. niger to the WSM, which was identified as BT-5-sulfate using mass spectrometry, UV spectroscopy, chemical hydrolysis, and 1H and 13C nuclear magnetic resonance spectroscopy. Similarly, the fungus had a capability of metabolizing xanthotoxol (XT), a structural isomer of BT, to a sulfated analog of BT-5-sulfate, presumably XT-8-sulfate. A possible enzyme-catalyzed pathway for the grapefruit FC metabolism involving the cleavage of the geranyl group and the addition of a sulfate group is proposed.

Recovery of pectic hydrocolloids and phenolics from huanglongbing related dropped citrus fruit

BACKGROUND Citrus pre-harvest fruit drop, caused by huanglongbing infection, has increased dramatically concomitant with declining tree health and crop harvest size. This loss of harvestable fruit is damaging to both growers and juice processors. Recovering and converting this fruit to alternative value added products would benefit the citrus industry. Therefore, we have explored the potential of using this fruit as a feedstock in our newly developed pilot scale continuous steam explosion process. RESULTS Whole fruits were converted to steam-exploded biomass using a continuous pilot scale process. The sugar composition of raw fruit and steam-exploded biomass was determined. Recovered pectic hydrocolloids and phenolic compounds were characterized. Pectic hydrocolloids comprised 78 g kg-1 of the dry material in the dropped fruit. Following the steam explosion process almost all of the pectic hydrocolloids were recoverable with a water wash. They could be functionalized in situ or separated from the milieu. Additionally, approximately 40% of the polymethoxylated flavones, 10% of the flavanone glycosides, 85% of the limonoids and almost 100% of hydroxycinnamates were simultaneously recovered. CONCLUSION The continuous steam explosion of pre-harvest dropped citrus fruit provides an enhanced, environmentally friendly method for the release and recovery of valuable coproducts from wasted biomass. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.