Extracts of Maqui ( Aristotelia chilensis ) and Murta ( Ugni molinae Turcz.): sources of antioxidant compounds and α-Glucosidase/α-Amylase inhibitors

The objective of this work was to evaluate the antioxidant and antihemolytic activities of crude, aqueous, and organic-aqueous extracts of maqui ( Aristotelia chilensis ) and murta ( Ugni molinae Turcz.), together with their inhibiting effect on enzymes involved in the metabolism of carbohydrates. Radical scavenging activity, inhibition of linoleic acid oxidation in a micellar system, antihemolytic activity, and inhibition of α-amylases and α-glucosidases were analyzed. Crude extracts of maqui leaves and fruits were found to be important sources of polyphenolic compounds, showing 69.0 ± 0.9 and 45.7 ± 1.1 mg GAE/g dm, respectively. Polyphenols from maqui leaves were active as antioxidants and antihemolytic compounds (p < 0.05), showing a noncompetitive inhibiting effect on α-glucosidase. Flavan-3-ol polymers and glycosylated flavonols, such as quercetin glucoside and kaempferol glucoside, were tentatively identified in extracts. This preliminary observation provides the basis for further examination of the suitability of polyphenol-enriched extracts from maqui and murta as nutritional or medicinal supplements with potential human health benefits.     

Effect of Protease Treatment Before Hydrolysis with α-Amylase on the Rate of Starch and Protein Hydrolysis of Maize,Whole Sorghum,and Decorticated Sorghum

We studied the effect of sorghum decortication and protease treatment on starch hydrolysis before liquefaction with thermoresistant α-amylase and the generation of free amino nitrogen (FAN) in preparation for subsequent steps of ethanol production. A bifactorial experiment with a level of confidence of P < 0.05 was designed to study differences among maize, whole sorghum, and decorticated sorghum and the effectiveness of the protease treatment before starch liquefaction. Sorghum was decorticated 9.7% to remove most of the pericarp and part of the germ and increase starch concentration. Starch concentration increased in decorticated kernels, whereas total phenols, fiber, and fat decreased. The decorticated sorghum had significantly higher starch and protein hydrolysis compared with the whole kernel. Protease treatment before liquefaction improved the rate of starch hydrolysis, especially in mashes from whole and decorticated sorghums. Whole and decorticated sorghum hydrolyzates treated with protease contained ≈50% more reducing sugars than the untreated counterparts. Maize yielded hydrolyzates with the the highest amount of FAN, followed by decorticated and whole sorghums. The maize and both sorghum hydrolyzates treated with protease contained ≈60 and 30% more FAN compared with the untreated counterparts. Both sorghum decortication and protease treatments before hydrolysis with α-amylase are recommended to increase ethanol yields, save processing time (and therefore energy), and to produce mashes with higher FAN content, which is considered as an important yeast substrate.     

Effects of Plant Residue Decomposition on Soil N Availability,Microbial Biomass and β-Glucosidase Activity During Soil Fertility Improvement in Ghana

With limited use of inorganic fertilizers on smallholder farms,plant residues could be viable alternatives for soil fertility improvement.This study was conducted to determine how residue quality and decomposition of nine plant species influence soil N availability,microbial biomass,andβ-glucosidase activity during soil fertility improvement.Significant differences in N concentration were found among the species,ranging from 12.2 g kg-1 in Zea mays to 39.2 g kg-1 in Baphia nitida.The C/N ratio was the highest in Z.mays(34.4),whereas lignin and polyphenol concentrations were the greatest in Acacia auriculiformis.The highest decomposition rate(0.251%per day)occurred in Tithonia diversifolia,and the lowest in A.auriculiformis,Albizia zygia,B.nitida,and Z.mays,with the half-lives of 28-56 d.Between 80%and 89%of N,P,K,Ca,and Mg were released from T.diversifolia in 7 d,compared with over 70%retention in A.auriculiformis,B.nitida,and Z.mays.The decomposition and nutrient release half-lives of Gliricidia sepium,Leucaena leucocephala,Azadirachta indica,and Senna spectabilis were less than 14 d.Soil mineral N,microbial biomass,andβ-glucosidase activity increased under all treatments,with T.diversifolia having the greatest effect.While N mineralization occurred in all of the species throughout the experiment,an initial N immobilization was recorded in the A.zy.gia,B.nitida,A.auriculiformis,and Z.mays treatments for up to 14 d.Decomposition and nutrient release rates,mineral N,soil microbial biomass,andβ-glucosidase activity were dependent on residue quality,and P and lignin levels,the lignin/N ratio,and the(lignin+polyphenol)/N ratio had the most significant effects(P≤0.05).     

Tea plantation destroys soil retention of NO3− and increases N2O emissions in subtropical China

The intensive conversion from woodland to tea plantation in subtropical China might significantly change the potential supply processes and cycling of inorganic Nitrogen (N). However, few studies have been conducted to investigate the internal N transformations involved in the production and consumption of inorganic N and N₂O emissions in subtropical soils under tea plantations. In a ¹⁵N tracing experiment, nine tea fields with different plantation ages (1-y, 5-y and 30-y) and three adjacent woodlands were sampled to investigate changes in soil gross N transformation rates in humid subtropical China. Conversion of woodland to tea plantation significantly altered soil gross N transformation rates. The mineralization rate (M_Norg) was much lower in soils under tea plantation (0.53–0.75 mg N kg⁻¹ d⁻¹) than in soil sampled from woodland (1.71 mg N kg⁻¹ d⁻¹), while the biological inorganic N supply (INS), defined as the sum of organic N mineralized into NH₄⁺ (M_Norg) and heterotrophic nitrification (O_Nrec), was not significantly different between soils under woodland and tea plantation, apart from soil under 30-y tea plantation which had the largest INS. Interestingly, the contribution of O_Nrec to INS increased from 19.6% in soil under woodland to 65.0–82.4% in tea-planted soils, suggesting O_Nrec is the dominant process producing inorganic N in tea-planted soils. Meanwhile, the conversion from woodland to tea plantation destroyed soil NO₃⁻ retention by increasing O_Nrec, autotrophic nitrification (O_NH4) and abiotic release of stored NO₃⁻ while decreasing microbial NO₃⁻ immobilization (I_NO3), resulting in greater NO₃⁻ production in soil. In addition, long-term tea plantation significantly enhanced the potential release of N₂O. Soil C/N was positively correlated with M_Norg and I_NO3, suggesting that an increase in soil C/N from added organic materials (e.g. rice hull) is likely to reduce the increased production of NO₃⁻ in the soils under tea plantation.     

In silico structural characteristics and α-amylase inhibitory properties of Ric c 1 and Ric c 3, allergenic 2S albumins from Ricinus communis seeds

The major Ricinus communis allergens are the 2S albumins, Ric c 1 and Ric c 3. These proteins contain a trypsin/α-amylase inhibitor family domain, suggesting that they have a role in insect resistance. In this study, we verified that Ric c 1 and Ric c 3 inhibited the α-amylase activity of Callosobruchus maculatus, Zabrotes subfasciatus, and Tenebrio molitor (TMA) larvae as well as mammalian α-amylase. The toxicity of 2S albumin was determined through its incorporation in C. maculatus larvae as part of an artificial diet. Bioassays revealed that 2S albumin reduced larval growth by 20%. We also analyzed the tridimensional structures of Ric c 1 and Ric c 3 by (a) constructing a comparative model of Ric c 1 based on Ric c 3 NMR structure and (b) constructing the theoretical structure of the Ric c 1-TMA and Ric c 3-TMA complexes. Our biological and theoretical results revealed that Ric c 1 and Ric c 3 are a new class of α-amylase inhibitors. They could potentially be used to help design inhibitors that would be useful in diverse fields, ranging from diabetes treatment to crop protection.     

Structure-activity relationships of α-, β(1)-, γ-, and δ-tomatine and tomatidine against human breast (MDA-MB-231), gastric (KATO-III), and prostate (PC3) cancer cells

Partial acid hydrolysis of the tetrasaccharide (lycotetraose) side chain of the tomato glycoalkaloid α-tomatine resulted in the formation of four products with three, two, one, and zero carbohydrate side chains, which were separated by high-performance liquid chromatography (HPLC) and identified by thin-layer chromatography (TLC) and liquid chromatography ion-trap time-of-flight mass spectrometry (LCMS-IT-TOF). The inhibitory activities in terms of IC(50) values (concentration that inhibits 50% of the cells under the test conditions) of the parent compound and the hydrolysates, isolated by preparative HPLC, against normal human liver and lung cells and human breast, gastric, and prostate cancer cells indicate that (a) the removal of sugars significantly reduced the concentration-dependent cell-inhibiting effects of the test compounds, (b) PC3 prostate cancer cells were about 10 times more susceptible to inhibition by α-tomatine than the breast and gastric cancer cells or the normal cells, (c) the activity of α-tomatine against the prostate cancer cells was 200 times greater than that of the aglycone tomatidine, and (d) the activity increased as the number of sugars on the aglycone increased, but this was only statistically significant at p < 0.05 for the normal lung Hel299 cell line. The effect of the alkaloids on tumor necrosis factor α (TNF-α) was measured in RAW264.7 macrophage cells. There was a statistically significant negative correlation between the dosage of γ- and α-tomatine and the level of TNF-α. α-Tomatine was the most effective compound at reducing TNF-α. The dietary significance of the results and future research needs are discussed.