Phenolic Amino Acids Research Articles

Cell-free hemoglobin and hemin catalyzing triclosan oxidative coupling in plasma: A novel exogenous phenolic pollutants coupling pathway

Previous studies reported that hemoprotein CYP450 catalyzed triclosan coupling is an “uncommon” metabolic pathway that may enhance toxicity, raising concerns about its environmental and health impacts. Hemoglobin, a notable hemoprotein, can catalyze endogenous phenolic amino acid tyrosine coupling reactions. Our study explored the feasibility of these coupling reactions for exogenous phenolic pollutants in plasma. Both hemoglobin and hemin were found to catalyze triclosan coupling in the presence of H₂O₂. This resulted in the formation of five diTCS-2 H, two diTCS-Cl-3 H, and twelve triTCS-4 H in phosphate buffer, with a total of nineteen triclosan coupling products monitored using LC-QTOF. In plasma, five diTCS-2 H, two diTCS-Cl-3 H, and two triTCS-4 H were detected in hemoglobin-catalyzed reactions. Hemin showed a weaker catalytic effect on triclosan transformation compared to hemoglobin, likely due to hemin dimerization and oxidative degradation by H₂O₂, which limits its catalytic efficiency. Triclosan transformation in the human plasma-like medium still occurs with high H₂O₂, despite the presence of antioxidant proteins that typically inhibit such transformations. In plasma, free H₂O₂ was depleted within 40 minutes when 800 µM H₂O₂ was added, suggesting a rapid consumption of H₂O₂ in these reactions. Antioxidative species, or hemoglobin/hemin scavengers such as bovine serum albumin, may inhibit but not completely terminate the triclosan coupling reactions. Previous studies reported that diTCS-2 H showed higher hydrophobicity and greater endocrine-disrupting effects compared to triclosan, which further underscores the potential health risks. This study indicates that hemoglobin and heme in human plasma might significantly contribute to phenolic coupling reactions, potentially increasing health risks.

Polyphenolic Gelatin-Based Bioadhesives

ConspectusBioadhesives are important for the future of medicine in their roles in wound closure and as measures to enhance wound healing. These adhesives are more effective and less invasive than conventional wound closure methods, such as surgical sutures or staples. Adhesive substances based on naturally occurring biological materials from living organisms harness phenolic compounds for their attachment to wet surfaces. For example, plants, such as Boston ivy, or animals, such as mussels, have evolved tissues that create optimal adhesion under a variety of challenging conditions, including in aqueous and saline environments. Current research aims at using biomimetic strategies to create a new generation of bioadhesives that will be better suited for medical use. Biomaterials design has evolved around integration of phenols with protein backbones among which gelatin has received particular attention due to its excellent bioactivity, biocompatibility, biodegradability, low cost, facile chemical tunability, and tissue-mimetic properties. Bioadhesion performance in these biomaterials is a strong function of polyphenolic functionality and the processing approach for their integration into hydrogel networks. A number of studies have used phenolic small molecules to modify biomacromolecules chemically for bioadhesion. One of the major hurdles in these studies is insufficient phenolic uptake due to low-yield modification chemistries and inherently limited functionalization capacity of proteins. Polyphenols are an attractive toolbox for bioadhesive design, as they not only enable stronger interactions with various substrates but also act as cross-linking points, strengthening polymer network cohesion. In addition, the cross-linking mechanism used for gelation of bioadhesives should be compatible with polyphenolic moieties, as, for instance, free-radical polymerization in the presence of phenolic compounds is compromised by their free-radical scavenging effects. Polyphenolic compounds derived synthetically from phenolic small molecules as well as those occurring naturally, such as tannins, have added a large library of additional functionality, such as antimicrobial and photothermal responsiveness, calling for further developments for applications in wound management.In this Account, we review several recent breakthroughs in polyphenol-integrated gelatin that have been analyzed in the context of their use as bioadhesives. Polyphenols play important roles in covalent and noncovalent interactions with functional groups in biological substrates, including keratins, connective tissue, or soft internal tissues. We consider different polyphenol-carrying compounds for modification including catecholamines, phenolic amino acids, tannins, and lignins. We then discuss how these polyphenolic materials can be fabricated to mimic naturally derived bioadhesives through infusion, physical mixing, and copolymerization. We discuss the implications of using these bioadhesives, questioning their viability and prospects. Finally, we highlight current challenges and future opportunities for taking polyphenolic bioadhesives closer to clinical translation.

Edukasi pada Ibu Balita tentang Pemanfaatan Daun Kelor untuk Pencegahan Stunting di Desa Talang Bukit Muaro Jambi

Moringa leaves as an alternative local food to fulfill toddler nutrition in preventing stunting. Moringa is a plant that has not been fully utilized. The nutritional content of Moringa includes essential amino acids, excellent protein, phenolic amino acids, a source of vitamins and β-carotene. The target of this community service activity is mothers who have a total of 56 toddlers. There is still a lack of mother's knowledge about the use of Moringa leaves for stunting prevention. Providing health education that is carried out is about Education on the Utilization of Moringa Leaves for the prevention of stunting in Talang Bukit Village using demonstration and lecture methods through leaflet and power point media. After education there was an increase in knowledge of 68.75% about the use of Moringa leaves for stunting prevention.

Stress Dissipation Encoded Silk Fibroin Electrode for the Athlete‐Beneficial Silk Bioelectronics (Adv. Sci. 8/2022)

Wearable Bioelectronics Wearable bioelectronics pursues superior biopolymer fabric enduring mechanical stress during workouts. In article number 2105420, Sangmin Lee, Jinkee Hong, and co-workers develop a super-tough silk fibroin fabric band by encoding the domains for stress dissipation. Precisely crosslinked phenolic amino acid offers sufficient toughness exceeding the fitness-originated fabric deformations. Furthermore, the proposed silk bioelectronics can assist the active workouts by relieving muscular fatigue and injuries.

Phytochemical characteristics and the study of acute toxicity of extracts from fruit Рrunus domestica

The increased demand for modern phytopreparations is dictated by their wide application in the complex treatment of various diseases, the presence of low toxicity and the pharmacoeconomic component. Phytochemical analysis of medicinal plants reveals not only potential therapeutic effects, but also assumes their toxicological properties. In this context, the Prunus domestica, widely spread on the territory of our country and well known for its medicinal properties and applications in folk medicine, has attracted our attention.
 The aim of the work was to investigate the phytochemical composition of extracts obtained from fruit Prunus domestica and to study their toxic properties.
 Phytochemical analysis of the extracts obtained from fruits Prunus domestica was carried out according to the original method of extracting biologically active compounds, using instrumental research methods using modern laboratory analytical equipment.
 Studies of the safety of four extracts from Prunus domestica (liquid EC-1, EC-2 and dry CEPC, CEV) with the calculation of median lethal doses were carried out on mice and rats with the single intragastric and intraperitoneal routes of administration according to the method of T. V. Pastushenko. The degree of toxicity was determined according to the classification of K. K. Sidorov.
 Phytochemical study of extracts from fruit Prunus domestica provided information on the presence in their chemical composition of flavonoids, the sum of phenolic compounds, anthocyanins, neutral sugars, amino acids, organic and hydroxycinnamic acids. A higher content of the sum of phenolic compounds in the aqueous (ЕС-1) and alcoholic extracts (ЕС-2) as well as the presence of neutral sugars as products of hydrolysis of homopolysaccharides (СEV extract) and heteropolysaccharides (CEPC extract).
 Experimental studies proved that EC-1, EC-2, CEPC and SEV extracts had low toxicity beyond 15 000 mg/kg when administered orally and 3 000 mg/kg when administered intraperitoneally. The LD50 of the studied extracts of mice and rats after intraperitoneal injection was determined, which was more than 3 000 mg/kg.
 The chemical composition of biologically active compounds of extracts from the fruit Prunus domestica, which provides promising directions for further study of their pharmacological properties, has been investigated.
 Analysis of experimental data on acute toxicity of the studied extracts showed that they belong to the IV class of toxicity “relatively harmless substances", according to K. K. Sidorov classification. The LD50 of extracts from the fruit Prunus domestica for oral administration could not be determined, and the LD50 of the studied extracts for mice and rats after intraperitoneal administration was more than 3 000 mg/kg.

Development of muffin with the incorporation of olive pomace flour, extra virgin olive oil and hydrolyzed soy protein

Olive pomace flour, extra virgin olive oil and hydrolyzed soy protein are ingredients rich in compounds with beneficial health properties, such as phenolic compounds, dietary fiber, amino acids and fatty acids. In this sense, the present study aimed to evaluate the influence of partial replacement of wheat flour, hydrogenated vegetable fat and sucrose by olive pomace flour, extra virgin olive oil and hydrolyzed soy protein, respectively, in muffin-type cakes. The determination of the ideal formulation with the alternative ingredients was carried out through the Response Surface Methodology, exploring a Simplex-Centroid Mixture Design using physicochemical parameters as dependent variables. The optimum point was obtained using 38.00 % olive pomace flour, 3.75 % extra virgin olive oil, and 4.05 % hydrolyzed soy protein. In general, it was observed that the alternative ingredients had positive effects on the texture profile of the muffins and provided products with darker shades, characteristics of the ingredients used. Nutritionally, an increase in total dietary fiber, ash and lipid content was observed. In contrast, the starch content decreased, but the total caloric value was similar between the standard sample and the optimum. Therefore, the partial replacement of ingredients demonstrated feasibility and potential for bakery goods.

Hippophae rhamnoides L. leaf and twig extracts as rich sources of nutrients and bioactive compounds with antioxidant activity

Plants have served for centuries as sources of compounds useful for human health such as antioxidant, anti-diabetic and antitumor agents. They are also rich in nutrients that improve the human diet. Growing demands for these compounds make it important to seek new sources for them. Hippophae rhamnoides L. is known as a plant with health-promoting properties. In this study we investigated the chemical composition and biological properties of bioactive components of ethanol extracts from leaves and twigs of H. rhamnoides L. Chemical components such as the total content of phenolic compounds, vitamins and amino acids and the antioxidant activities of these compounds in cellular and cell-free systems were assessed. The results suggest that the studied extracts are rich in bioactive compounds with potent antioxidant properties. Cytotoxicity and hemotoxicity assays showed that the extracts had low toxicity on human cells over the range of concentrations tested. Interaction with human serum albumin was investigated and conformational changes were observed. Our results indicate that leaf and twig extracts of H. rhamnoides L. should be considered as a non-toxic source of bioactive compounds which may be of interest to the food, pharmaceutical and cosmetic industries.

Production of an Anise- and Woodruff-like Aroma by Monokaryotic Strains of Pleurotus sapidus Grown on Citrus Side Streams.

The production of natural flavors by means of microorganisms is of great interest for the food and flavor industry, and by-products of the agro-industry are particularly suitable as substrates. In the present study, Citrus side streams were fermented using monokaryotic strains of the fungus Pleurotus sapidus. Some of the cultures exhibited a pleasant smell, reminiscent of woodruff and anise, as well as herbaceous notes. To evaluate the composition of the overall aroma, liquid/liquid extracts of submerged cultures of a selected monokaryon were prepared, and the volatiles were isolated via solvent-assisted flavor evaporation. Aroma extract dilution analyses revealed p-anisaldehyde (sweetish, anisic- and woodruff-like) with a flavor dilution factor of 218 as a character impact compound. The coconut-like, herbaceous, and sweetish smelling acyloin identified as (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone also contributed to the overall aroma and was described as an aroma-active substance with an odor threshold in air of 0.2 ng L−1 to 2.4 ng L−1 for the first time. Supplementation of the culture medium with isotopically substituted l-tyrosine elucidated this phenolic amino acid as precursor of p-anisaldehyde as well as of (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone. Chiral analysis via HPLC revealed an enantiomeric excess of 97% for the isolated product produced by P. sapidus.

Stress Dissipation Encoded Silk Fibroin Electrode for the Athlete-Beneficial Silk Bioelectronics.

The kinetic body motions have guided the core‐shell fabrics of wearable bioelectronics to be elastoplastic. However, the polymeric electrodes follow the trade‐off relationship between toughness and stretchability. To this end, the stress dissipation encoded silk fibroin electrode is proposed as the core electrode of wearable bioelectronics. Significantly, the high degree of intrinsic stress dissipation is realized via an amino acid crosslink. The canonical phenolic amino acid (i.e., tyrosine) of silk fibroin is engineered to bridge the secondary structures. A sufficient crosslink network is constructed when tyrosine is exposed near the amorphous strand. The stress dissipative tyrosine crosslink affords 12.5‐fold increments of toughness (4.72 to 58.9 MJ m−3) and implements the elastoplastic silk fibroin. The harmony of elastoplastic core electrodes with shell fabrics enables the wearable bioelectronics to employ mechanical performance (elastoplasticity of 750 MJ m−3) and stable electrical response. The proposed wearable is capable of assisting the effective workouts via triboelectricity. In principle, active mobility with suggested wearables potentially relieves muscular fatigues and severe injuries during daily fitness.

Kistamicin biosynthesis reveals the biosynthetic requirements for production of highly crosslinked glycopeptide antibiotics

Kistamicin is a divergent member of the glycopeptide antibiotics, a structurally complex class of important, clinically relevant antibiotics often used as the last resort against resistant bacteria. The extensively crosslinked structure of these antibiotics that is essential for their activity makes their chemical synthesis highly challenging and limits their production to bacterial fermentation. Kistamicin contains three crosslinks, including an unusual 15-membered A-O-B ring, despite the presence of only two Cytochrome P450 Oxy enzymes thought to catalyse formation of such crosslinks within the biosynthetic gene cluster. In this study, we characterise the kistamicin cyclisation pathway, showing that the two Oxy enzymes are responsible for these crosslinks within kistamicin and that they function through interactions with the X-domain, unique to glycopeptide antibiotic biosynthesis. We also show that the kistamicin OxyC enzyme is a promiscuous biocatalyst, able to install multiple crosslinks into peptides containing phenolic amino acids.

L-DOPA Trends in Different Tissues at Early Stages of Vicia faba Growth: Effect of Tyrosine Treatment

The nonprotein amino acid Levo-3,4-dihydroxyphenylalanine (L-DOPA) has insecticidal, allelochemical, and antiparkinsonian effects. The aim of this research was to assess L-DOPA content in different tissues of Vicia faba (cv. Super Agua Dulce), and to verify if treatment with the phenolic amino acid L-4-hydroxyphenylalanine (tyrosine) had an effect on such content. Under light germination, control and tyrosine-treated early seedling stages of V. faba were studied and L-DOPA was quantified spectrophotometrically (Arnow’s method) and by high-performance thin-layer chromatography (HPTLC), as well. Additionally, tyrosinase (TYROX) and guaiacol peroxidase (GPX) activities (considered markers of a phenolic compounds metabolism) were quantified as germination proceeded. Different organs (roots, sprouts, and seeds) and different developmental stages were considered. Steady high L-DOPA concentrations were found in untreated sprouts and roots compared to seeds, as time progressed. While TYROX activity was not detected in these experiments, GPX had diverse trends. In control tissues, GPX increased in seed tissue as germination progressed, whereas in roots and sprouts, a decreasing GPX activity was observed. Tyrosine exposure decreased L-DOPA content, and decreased or did not change GPX activity (depending on the organ). Both Arnow’s and HPTLC methods were consistent in terms of tendencies, except for the scarce contents found in seeds, in which HPTLC was more sensitive. The richest source of L-DOPA was found in shoots (untreated), reaching as high as 125 mg g−1 DW (12% in DW) (the highest content reported in fava bean seedlings until now), whereas the smallest L-DOPA content was found in seeds. The importance of light germination conditions is discussed in terms of L-DOPA yield and from a physiological perspective. It is concluded that V. faba (cv. Super Agua Dulce) shoots are a good source of L-DOPA and that tyrosine addition (0.55 mM) decreases L-DOPA content in actively growing tissues (shoots and roots).

Acidulant effect on greening, reducing capacity, and tryptophan fluorescence of sunflower butter cookie dough during refrigerated storage.

Sunflower seed derived butter can be a source of protein and phenolic antioxidants in refrigerated dough. Chlorogenic quinone-amino acid induced greening can however occur at alkaline pH, which could result in less bioavailable conjugated phenol-amino acids. Acidulants were tested as potential anti-greening ingredients in refrigerated chemically leavened cookie dough. Effect of refrigerated storage time, leavening agents and acidulants on tryptophan fluorescence (λex=280 nm, λem=300-500 nm), color (hunter L*, a*, b* color scale), reducing capacity [1,1'-diphenyl-2-picryl-hydrazyl (DPPH) and Folin-Ciocalteu reducing capacity (FCRC)], and hydroxycinnamic acids were measured. The pH range of acidified doughs was 4.83-6.98 compared to 7.65-9.18 in non-acidified leavened doughs after 24 days. Greening was higher in baking soda dough control (a*=-0.54) than baking powder dough control (a*=2.98) after 24 days, attributed to higher pH (9.18) of the former compared to pH7.14 in the later. Tryptophan fluorescence intensity in baking soda dough decreased in the order: control>glucono-delta lactone≈citric acid after 24 days. The DPPH and FCRC of acidified doughs were greater than corresponding control doughs. The use of acidulants would prevent greening in sunflower dough without lowering its phenolic concentration, making use of sunflower butter in refrigerated dough for baked goods feasible. © 2018 Society of Chemical Industry.

Evaluation of Phenolic Compounds, Lignin, Amino Acids and Carbohydrates in Theobroma cacao L. from Three Different Climate Regions in Venezuela

In Venezuela, Criollo cacao crops are distributed in different regions (eastern, central and western), and under different exploitation systems, and, in each of these regions, there is a uniqueness of materials with characteristics associated to an intrinsic, differential quality that could potentially affect chocolate quality. These regions have inherent climates that are significantly different; however, there is a lack of consistent technical information about the real effects of environmental factors on the organoleptic quality of cacao. Therefore, the present work aims to evaluate the content of important components of cacao, such as phenolic compounds, lignin, amino acids, and carbohydrate, in six Theobroma cacao L clones, cultivated in three different agro-climatic locations: humid, semi-humid and dry tropical forest. It was found that production of phenolic compounds and lignin vary in clones according to their location, with the highest values found in the humid forest and the lowest in the dry climate. Non-structural carbohydrates, on the other hand, were found in greater amounts in specimens from the dry forest. The largest production of proline was found in the humid forest for most of the clones, implying that high humidity levels promote the production of amino acids, a pattern followed by phenolic compound content as well. The results presented in this study indicate that there is a climate-dependent production of important metabolites, which play an important role in the organoleptic properties of cacao, and this could potentially translate into different levels of resistance to stress and diseases.

Antioxidant Properties of Herbal Mixtures Improving Cognitive-Mnestic Functions

Decoctions of herbal mixtures I (including 30% Filipendula ulmaria meadowsweet grass, 10% bilberry shoots, and 60% Bergenia crassifolia green leaves) and II (60% meadowsweet grass, 10% bilberry shoots, and 30% bergenia green leaves) exhibited antioxidant activity. Biologically active substances of herbal mixture I exhibited predominantly catalytic decomposition of hydrogen peroxide formed during electroreduction of oxygen. Active substances of herbal mixture II interacted with oxygen radicals generated as a result of oxygen electroreduction on the electrode surface (EC mechanism) and were more effective than both dihydroquercetin and ascorbic acid. Herbal mixtures I and II normalized the content of thiobarbiturate-reactive products in brain homogenates under conditions of hypoxia-activated lipid peroxidation. In addition, herbal mixture II reduced the concentration of antiradical antioxidants in the lipid extracts. The antioxidant properties were inherent to a greater extent in mixture II dominated by meadowsweet grass, which contained the most complete sum of biologically active phenolic substances (simple phenols, flavonoids, hydroxycoumarins, phenolcarboxylic acids, mainly hydrolyzable tannins), amino acids, and macro- and microelements.

"Inherently chiral" thiophene-based electrodes at work: a screening of enantioselection ability toward a series of pharmaceutically relevant phenolic or catecholic amino acids, amino esters, and amine.

"Inherently chiral" thiophene-based electroactive oligomer films have recently been shown to exhibit outstanding chirality manifestations. One of the most exciting among them is an unprecedented enantioselection ability as electrode surfaces. In fact, in preliminary chiral voltammetry experiments, the new electrodes have been shown to both discriminate the enantiomers of chiral probes (either enantiopure or ina mixture, in terms of large differences in peak potentials) and quantify them (in terms of linear dynamic ranges in peak currents), without the need for preliminary separation steps. Such ability has now been tested on a series of chiral DOPA-related molecules, from phenolic amino acid tyrosine (together with its methyl ester) to catecholic amino acid DOPA (together with its methyl ester), to catecholamine epinephrine (adrenaline). The wide-range enantioselectivity of the new inherently chiral electrode surfaces is fully confirmed, as large peak potential differences are obtained for probe enantiomers of the whole series working in common aqueous buffers. Moreover, interesting modulating effects on enantiodiscrimination can be observed as a function of both molecular structure and pH. Graphical abstract Inherently chiral thiophene-based electrodes at work with pharmaceutically relevant probes.

Selenium Biofortification in Radish Enhances Nutritional Quality via Accumulation of Methyl-Selenocysteine and Promotion of Transcripts and Metabolites Related to Glucosinolates, Phenolics, and Amino Acids.

Two selenium (Se) fertilization methods were tested for their effects on levels of anticarcinogenic selenocompounds in radish (Raphanus sativus), as well as other nutraceuticals. First, radish was grown on soil and foliar selenate applied 7 days before harvest at 0, 5, 10, and 20 mg Se per plant. Selenium levels were up to 1200 mg Se/kg DW in leaves and 120 mg Se/kg DW in roots. The thiols cysteine and glutathione were present at 2–3-fold higher levels in roots of Se treated plants, and total glucosinolate levels were 35% higher, due to increases in glucoraphanin. The only seleno-aminoacid detected in Se treated plants was Se-methyl-SeCys (100 mg/kg FW in leaves, 33 mg/kg FW in roots). The levels of phenolic aminoacids increased with selenate treatment, as did root total nitrogen and protein content, while the level of several polyphenols decreased. Second, radish was grown in hydroponics and supplied with 0, 5, 10, 20, or 40 μM selenate for 1 week. Selenate treatment led to a 20–30% increase in biomass. Selenium concentration was 242 mg Se/kg DW in leaves and 85 mg Se/kg DW in roots. Cysteine levels decreased with Se in leaves but increased in roots; glutatione levels decreased in both. Total glucosinolate levels in leaves decreased with Se treatment due to repression of genes involved in glucosinolates metabolism. Se-methyl-SeCys concentration ranged from 7–15 mg/kg FW. Aminoacid concentration increased with Se treatment in leaves but decreased in roots. Roots of Se treated plants contained elevated transcript levels of sulfate transporters (Sultr) and ATP sulfurylase, a key enzyme of S/Se assimilation. No effects on polyphenols were observed. In conclusion, Se biofortification of radish roots may be achieved via foliar spray or hydroponic supply. One to ten radishes could fulfill the daily human requirement (70 μg) after a single foliar spray of 5 mg selenate per plant or 1 week of 5–10 μM selenate supply in hydroponics. The radishes metabolized selenate to the anticarcinogenic compound Se-methyl-selenocysteine. Selenate treatment enhanced levels of other nutraceuticals in radish roots, including glucoraphanin. Therefore, Se biofortification can produce plants with superior health benefits.

Effects of thermal processing and pulp filtration on physical, chemical and sensory properties of winter melon juice.

Winter melon (Benincasa hispida) is a widely consumed crop in Asia, and believed to impart special benefits to human health. The nutritional composition and sensory properties of four juice types, resulting from a combination of pulp levels (low/high pulp, LP/HP) and thermal processing (with/without boiling, B/NB), LPNB, HPNB, LPB and HPB, were compared. The juices had low sugars (< 20 g kg-1 ) and low titratable acidity (about 2 g kg-1 ). The insoluble solids, glucose, fructose and citric acid content in LP juice were significantly lower than in HP juice. The phenolic amino acids phenylalanine, tyrosine, and tryptophan were detected at 10-45 mg L-1 levels, and the antioxidant activity ranged from 36 to 49 mg gallic acid L-1 . C6 and C9 aldehydes were mainly found in HP juice, and boiling induced the accumulation of sulfur compounds and C5 aldehydes. The LPNB juice showed the highest acceptability in the sensory panel. The frozen concentrated orange juice (FCOJ) reconstituted with LPNB was preferable to regular FCOJ for 31% of panelists and not different for 20% of panelists. The low sugar/low acid LPNB juice with 'fresh' flavor could be developed to replace water for reconstituting FCOJ with enhanced nutritional value. © 2016 Society of Chemical Industry.

Regeneration of β-Carotene from the Radical Cation by Tyrosine and Tryptophan.

The phenolic amino acid tyrosine (Tyr) was found more efficient in regenerating β-carotene (β-Car) from the radical cation (β-Car(•+)) than tryptophan (Trp) in the presence of base for conditions where the reduction potentials for Trp and Tyr are comparable. Electron transfer from Tyr in 4:1 chloroform/methanol to β-Car(•+) in the presence of excess base, (CH3)4N(+)OH(-), had a rate close to diffusion control and a second-order rate constant in agreement with the Marcus theory for electron transfer when compared to plant phenols. A maximum of 40% β-Car was regenerated for ten times excess of Tyr as studied by 532 nm laser flash photolysis followed by transient absorption spectroscopy in the visible and near-infrared regions. The nonregenerated fraction of β-Car is assigned to secondary degradation processes. For Trp, the rate constant for regeneration of β-Car(•+) was 1 order of magnitude smaller compared to Tyr and slower than expected from Marcus theory by comparison with plant phenols.

"Cross-linked fibrous" spherulites formed from a low molecular weight compound, Fmoc-functionalized phenolic amino acid.

While biomacromolecules such as proteins are shown to form fibrous spherulites, which are generally "semicrystalline" in nature, here we show that a simple, low molecular weight compound such as fluorenylmethoxycarbonyl-functionalized phenolic amino acid (Fmoc-l-tyrosine) can form "fibrous" spherulites with highly "cross-linked" microfibrils using the supramolecular self-assembly process.

Phytochemical and IR -Spectrum analysis of Strychnos potatorum linn

The present paper deals with the phytochemical characteristics of leaves and bark of an endangered medicinally important tree species of strychnos potatorum . Preliminary phytochemical screening revealed the presence of alkaloids, flavonoids, saponins, carbohydrates, tannins, sterols, glycosides, oil and fats, phenolic compounds, protein and amino acids, gums and mucilage. The functional groups were identified through IR spectrum.