Content of major classes of polyphenolic compounds, antioxidant, antiproliferative, and cell protective activity of pecan crude extracts and their fractions

In vitro and in vivo evaluation of the effects of condensed tannins and catechins monomers on antioxidant and intestinal health of Chinese seabass (Lateolabrax maculatus)

Plant-derived condensed tannins (CT) exhibit strong bioactivity of antioxidant, immunostimulation and intestinal protection, but with little clues of the mechanism of action. Since CT are consist of catechins (CAs) monomers, e.g., catechin (CA), epicatechin (EC) and epigallocatechin (EG), we motivated to use the monomers to explore the underlying mechanisms in a seabass model focusing on anti-oxidative stress and intestinal health of Lateolabrax maculatus. An in vitro intestinal primary cell oxidative stress model induced by hydrogen peroxide was set up to assess the antioxidant and immune activities of CT and CAs. Another 56-d feeding trial with 800 fish was conducted to evaluate the effects of CT and CAs on growth performance, intestinal permeability and digestive enzyme activities, intestinal morphology and antioxidant status, and intestinal bacterial flora of fish. Five diets were prepared to contain 0 (G1) and 1 g/kg of CT, CA, EC and EG. Fish were randomly distributed into 20 tanks with 4 tanks per diet and 40 fish per tank, and were fed to apparent satiation twice daily. Results showed that CT and CAs exhibited similar effects in alleviating hydrogen peroxide-induced cell injury by activating nuclear factor erythroid 2-related factor 2 gene expression, and improving antioxidant and immune capacities. Dietary CT and CAs enhanced intestinal antioxidant ability and increased (p < 0.05) the abundance of intestinal Firmicutes, Proteobacteria and Bacteroidetes to oxidative stress tolerant. With a dose of 1 g/kg CT and CA promoted (p < 0.05) intestinal total antioxidant capacity, but slightly induced intestinal injury mainly due to increased (p < 0.05) intestinal permeability (as reflected by increased lipopolysaccharide concentrations) and inhibited (p < 0.05) digestion (as reflected by the decreased trypsin and lipase activities) of fish. In summary, CT and CAs protect intestine from oxidative stress and improve intestinal antioxidant capacity by stimulating antioxidant enzyme system and bacterial flora. CA and EC show similar or superior antioxidant activity than CT.

Inhibition of human starch digesting enzymes and intestinal glucose transport by walnut polyphenols

One approach to controlling type 2 diabetes (T2D) is to lower postprandialglucose spikesby slowing down the digestion of carbohydrates and the absorption of glucose in the small intestine. The consumption of walnuts is associated with a reduced risk of chronic diseases such as T2D, suggested to be partly due to the high content of (poly)phenols. This study evaluated, for the first time, the inhibitory effect of a (poly)phenol-rich walnut extract on human carbohydrate digesting enzymes (salivary and pancreatic α-amylases, brush border sucrase-isomaltase) and on glucose transport across fully differentiated human intestinal Caco-2/TC7 monolayers. The walnut extract was rich in multiple (poly)phenols (70 % w/w) as analysed by Folin-Ciocalteau and by LCMS. It exhibited potent inhibition of both human salivary (IC50: 32.2 ± 2.5 µg walnut (poly)phenols (WP)/mL) and pancreatic (IC50: 56.7 ± 1.7 µg WP/mL) α-amylases, with weaker effects on human sucrase (IC50: 990 ± 20 µg WP/mL), maltase (IC50: 1300 ± 80 µg WP/mL), and isomaltase (IC25: 830 ± 60 µg WP/mL) activities. Selected individual walnut (poly)phenols inhibited human salivary α-amylase in the order: 1,3,4,6-tetragalloylglucose > ellagic acid pentoside > 1,2,6-tri-O-galloyl-β-D-glucopyranose, with no inhibition by ellagic acid, gallic acid and 4-O-methylgallic acid. The (poly)phenol-rich walnut extract also attenuated (up to 59 %) the transfer of 2-deoxy-D-glucose across differentiated Caco-2/TC7 cell monolayers. This is the first report on the effect of (poly)phenol-rich extracts from any commonly-consumed nut kernel on any human starch-digesting enzyme, and suggests a mechanism through which walnut consumption may lower postprandial glucose spikes and contribute to their proposed health benefits.

Cytotoxic, antioxidant, and cytoprotective properties of polyphenol-enriched extracts from pecan nutshells in MDA-MB-231 breast cancer cells

Phenolic compounds present in plants have demonstrated several biological properties such as antioxidant, antitumor, cardioprotective, and antiproliferative. On the other hand, doxorubicin, a chemotherapeutic widely used to treat breast cancer, usually exhibits chronic cardiotoxicity associated with oxidative stress. Therefore, we aimed to study the effects of phenolic compound-enriched extract (PCEE) with doxorubicin in breast cancer. To achieve this, after an SPE-C18 -column purification process of crude extracts obtained from pecan nutshells (Carya illinoinensis), the resulting PCEE was used to evaluate the cytotoxicity and antioxidant properties against the human breast cancer cell line MDA-MB-231 and the normal-hamster ovary cell line CHO-K1. PCEE was selectively cytotoxic against both cell lines, with an IC50 value (≈26.34 mg/L) for MDA-MB-231 lower than that obtained for CHO-K1 (≈55.63 mg/L). As a cytotoxic mechanism, PCEE inhibited cell growth by G2/M cell cycle arrest in MDA-MB-231 cells. Simultaneously, the study of the antioxidant activity showed that PCEE had a cytoprotective effect, evidenced by reduced ROS production in cells with oxidative stress caused by doxorubicin. The results highlight PCEE as a potential antitumor agent, thus revaluing it as an agro-industrial residue.

CcMYB12 Positively Regulates Flavonoid Accumulation during Fruit Development in Carya cathayensis and Has a Role in Abiotic Stress Responses

Flavonoid, an important secondary metabolite in plants, is involved in many biological processes. Its synthesis originates from the phenylpropane metabolic pathway, and it is catalyzed by a series of enzymes. The flavonoid biosynthetic pathway is regulated by many transcription factors, among which MYB transcription factors are thought to be key regulators. Hickory (Carya cathayensis) is an economic forest tree species belonging to the Juglandaceae family, and its fruit is rich in flavonoids. The transcriptome of exocarp and seed of hickory has previously been sequenced and analyzed by our team, revealing that CcMYB12 (CCA0691S0036) may be an important regulator of flavonoid synthesis. However, the specific regulatory role of CcMYB12 in hickory has not been clarified. Through a genome-wide analysis, a total of 153 R2R3-MYB genes were identified in hickory, classified into 23 subclasses, of which CcMYB12 was located in Subclass 7. The R2R3-MYBs showed a differential expression with the development of hickory exocarp and seed, indicating that these genes may regulate fruit development and metabolite accumulation. The phylogenetic analysis showed that CcMYB12 is a flavonol regulator, and its expression trend is the same as or opposite to that of flavonol synthesis-related genes. Moreover, CcMYB12 was found to be localized in the nucleus and have self-activation ability. The dual-luciferase reporter assay demonstrated that CcMYB12 strongly bonded to and activated the promoters of CcC4H, CcCHS, CcCHI, and CcF3H, which are key genes of the flavonoid synthesis pathway. Overexpression of CcMYB12 in Arabidopsis thaliana could increase the content of total flavonoids and the expression of related genes, including PAL, C4H, CHS, F3H, F3’H, ANS, and DFR, in the flavonoid synthesis pathway. These results reveal that CcMYB12 may directly regulate the expression of flavonoid-related genes and promote flavonoid synthesis in hickory fruit. Notably, the expression level of CcMYB12 in hickory seedlings was significantly boosted under NaCl and PEG treatments, while it was significantly downregulated under acid stress, suggesting that CcMYB12 may participate in the response to abiotic stresses. The results could provide a basis for further elucidating the regulation network of flavonoid biosynthesis and lay a foundation for developing new varieties of hickory with high flavonoid content.

Plant-based pecan nut cake beverage enrichment of phytochemicals and antioxidant properties using multi-stage block freeze concentration

Pecan nut (Carya illinoinensis) processing to obtain oil generates circa 37% of press cake, which is currently underutilized and primarily employed as animal feed. Due to its nutritional- and bioactive-rich composition, pecan nut cake (PNC) can be used as raw material for plant-based beverages, whose properties may be enhanced using a non-thermal technology based on block freeze concentration (BFC). The effect of five-stage BFC on total solids content (TSC), pH, color parameters, retention of phytochemicals, and the antioxidant activity (AA) of a pecan nut cake beverage (PNB) was assessed in this work. BFC afforded 98% (w/w) solids retention after three stages and 85% efficiency after four stages. The process also provided a 254% concentration factor in stage 5. In the last step, approximately a 64% increase in TSC and a slight decrease (7.3%) in pH compared to the control PNB was observed. In addition, total phenolic compounds, condensed tannins, total flavonols, and AA were significantly (P < 0.05) improved after the BFC, resulting in a 2.6-10.2- and 1.9-5.8-fold increase in phytochemicals and antioxidants, respectively. On the other hand, BFC caused the darkening of concentrates due to TSC and bioactive compounds retention. The processing strategy evaluated herein indicated a great potential of PNC as a raw material for obtaining high-quality ingredients for the food industry, which may reduce agro-industrial waste production and add value to a coproduct rich in nutrients and biocompounds with potential biological activity.

Graphical Abstract

A comparative study of antimicrobial, anti-quorum sensing, anti-biofilm, anti-swarming, and antioxidant activities in flower extracts of pecan (Carya illinoinensis) and chestnut (Castanea sativa)

Antibiotic resistance, which has increased rapidly in recent years because of uncontrolled and unconscious antibiotic consumption, poses a major threat to public health. The inadequacy of existing antibiotics has increased the need for new, effective, and less toxic antibiotic raw materials or antibiotic derivatives. Pecan (Carya illinoinensis) and Chestnut (Castanea sativa) flowers possess abundant pollen contents and exhibit similar morphological features. The purpose of this study was to compare these two flower extracts in terms of their antimicrobial and antioxidant activities. Total phenolic content, total flavonoid contents, and phenolic components were also analyzed in aquatic and ethanolic extracts. Antioxidant activities were measured using ferric reducing/antioxidant capacity (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods. Antimicrobial and antifungal activities were compared by means of agar diffusion tests against bacteria including Staphylococcus aureus, Bacillus cereus, Mycobacterium smegmatis, Acinetobacter haemolyticus, and Chromobacterium violaceum, and the yeasts Candida albicans and Candida parapsilosis. Anti-quorum sensing (anti-QS), anti-biofilm, and anti-swarming (SW) activities were also studied against Chromobacterium violaceum ATCC 31532, Chromobacterium violaceum ATCC 12472, and Pseudomonas aeruginosa PA01, respectively. Both extracts were rich in ellagic acid and gallic acid and exhibited similar antioxidant properties. Both flower extracts exhibited high antimicrobial and antifungal activities as well as anti-biofilm, anti-QS, and anti-SW activities.

Enzyme inhibitory activities of phenolic compounds in pecan and the effect on starch digestion

Pecan has been widely recognized for its high phenolic content and related health benefits. Previous studies indicated that pecan consumption might be beneficial in treating type 2 diabetes mellitus (T2DM). The objective of this study was to investigate the enzyme inhibitory activities of pecan phenolic compounds (PPC) and the effect in starch hydrolysis by in vitro simulation digestion. PPC was extracted with a solvent mixture from pecan powder and freeze-dried. PPC was tested for the inhibitory effects on α-amylase and α-glucosidase via enzyme kinetics study. Static in vitro digestion trials were conducted to evaluate the effect of intake of PPC and pecan powder on starch digestion. PPC displayed a potent inhibition effect against α-amylase and α-glucosidase with IC₅₀ of 77.9 μg/mL and 9.02 μg/mL, respectively. Both PPC and pecan powder inhibited starch hydrolysis during in vitro digestion. However, the level of inhibition was lower than that from the catalytic kinetics study, and PPC exhibited a higher inhibition effect than pecan powder. The results confirmed the potential of PPC as a novel enzyme inhibitor for T2DM management. The information is helpful to promote the intake of pecan nuts for health-enhancing effects.

High-added value co-products obtained from pecan nut (Carya illinoinensis) using a green extraction technology

Abstract

The aqueous (AF) and solid (SF) fractions obtained as co-products in the aqueous extraction of pecan nut oil assisted by Alcalase^® were evaluated. In the AF, the degree of protein hydrolysis (DH) and the electrophoretic profile of protein hydrolysates, phenolic compounds, and antioxidant capacity (reducing potential of the hydrophilic compounds, RPHC, 2,2-diphenyl-1-picrylhydrazyl, DPPH; and inhibition of lipid peroxidation) were determined. The proximate composition and microstructure were evaluated in SF. The results indicated a DH of 3.9%. The sample treated with the enzyme (ET) showed a molecular weight of proteins lower than 15 kDa. The ET showed higher content of phenolics (726.3 mg GAE/100 g) and antioxidant capacity higher than the sample without enzymatic treatment. The SF showed a residual lipid content rich in oleic and linoleic acids. Furthermore, changes in the proximate composition and the microstructure were observed. The results indicate the potentiality of hydrolyzed fractions for application in food.

Graphic abstract

Phytochemical content and potential health applications of pecan [Carya illinoinensis (Wangenh) K. Koch] nutshell

BACKGROUND

The pecan nutshell contains phytochemicals with various biological activities that are potentially useful in the prevention or treatment of diseases such as cancer, diabetes, and metabolic imbalances associated with heart diseases.

OBJECTIVE

To update this topic by means of a literature review and include those that contribute to the knowledge of the chemical composition and biological activities of pecan nutshell, particularly of those related to the therapeutic potential against some chronic degenerative diseases associated with oxidative stress.

METHOD

Exhaustive and detailed review of the existing literature using electronic databases.

CONCLUSION

The pecan nutshell is a promising natural product with pharmaceutical uses in various diseases. However, additional research related to the assessment of efficient extraction methods and characterization, particularly the evaluation of the mechanisms of action in new in vivo models, is necessary to confirm these findings and development of new drugs with therapeutic use.

Extraction of phenolic compounds from the shells of pecan nuts with cytotoxic activity through apoptosis against the colon cancer cell line HT-29

The water extraction of phenolic compounds from two varieties ("Mahan" and "Marameck") of pecan nutshells (Carya illinoinensis) without and with sonication, varying the solvent/solid ratio (S), the pH, and the refluxing time (t), was studied. Additionally, the in vitro cytotoxicity and the determination of the cell death mechanism of the extracts against the colon cancer cell line HT-29 were investigated. The content of total phenolic compounds (TPC) of "Marameck" nutshells resulted higher than for the "Mahan" variety, and the pH increase resulted in higher TPC contents for both cultivars. The optimized conditions for TPC extraction without and with sonication resulted: S = 33 ml/g, pH = 12, and t = 9.6 min, and yielded ≈ 70 and 90 mg/g of TPC for "Mahan" and "Marameck" nutshells, respectively. The optimized extracts of pecan nutshells without sonication from both cultivars presented similar cytotoxicity against HT-29 colon cancer cells (IC₅₀  ≈ 50 µg/ml), higher than for sonicated extracts (IC₅₀ ≈ 88 and 138 µg/ml for "Mahan" and "Marameck," respectively). Cell death through apoptosis was the main mechanism of cell death induced by the nutshell extracts. PRACTICAL APPLICATION: The extraction of phenolic compounds (TPC) from the residues of two varieties of pecan nutshells ("Mahan" and "Marameck") was studied. An optimal combination of variables within the pH range that minimizes the solvent-to-solid ratio (S) and the time of refluxing (t), saving at the same time, water and energy, was set up. The phenolic compound extracts obtained from the residues of the pecan nuts exhibit cytotoxic effects against colon cancer cells and could be of interest as an alternative treatment of different types of cancer. Additionally, these extracts may be of importance to the food industry as they can be used as antioxidant agents in food formulation. Also, the high levels of anthocyanidins obtained from the pecan nut extracts after proanthocyanidins' strong acid hydrolysis can be purified and employed as natural red dyes.

Antioxidant Properties of Pecan Shell Bioactive Components of Different Cultivars and Extraction Methods

Pecan shells are a rich source of various bioactive compounds with potential antioxidant and antimicrobial properties. This study investigated the effect of pecan variety and method extraction on the antioxidant property of shell extracts. Twenty different varieties of pecan shells were subjected to either aqueous or ethanolic extraction and were examined for total phenolics and antiradical activity. The phenolic content and antiradical activity of shell extracts were significantly (p < 0.05) varied with different pecan cultivars. The total phenolic content of ethanol extracts ranged from 304.2 (Caddo) to 153.54 (Cherokee) mg GAE/g of dry extract and was significantly greater (p < 0.05) than those obtained by aqueous extraction. The antiradical activity of ethanol extracts ranged from 840.6 (Maramec) to 526.74 (Caper Fear) mg TEg-1, while aqueous extracts ranged from 934.9 (Curtis) to 468.3 (Elliot) mg TEg-1. Chemical profiling of the crude and acid hydrolyzed extracts was performed by reverse phase high performance liquid chromatography and flow injection electrospray ionization mass spectrometry. Lignin degradation products such as lignols, dilignols, trilignols, and oligolignols were found to be the major components of tested extracts. Phenolic content and antiradical activity of pecan shell extracts are significantly varied with cultivars and methods of extraction.

Pecan pericarp extract protects against carbon tetrachloride-induced liver injury through oxidative mechanism in rats

The purpose of this study was to quantify the proanthocyanidin content of pecan (Carya illinoinensis) pericarp extract (PPE) and to assess its useful impacts against carbon tetrachloride (CCl4)-induced hepatotoxicity. Rats were randomly divided into four groups: Group 1: received intraperitoneal injection of saline solution, Group 2: was injected with PPE (25 mg/kg body weight) for 10 consecutive days, Group 3: received CCl4 (0.5 ml/kg, subcutaneous injection), Group 4: was coadministred with PPE + CCl4. The CCl4 was administered every 3 days during 10 days. Results revealed the presence of a high amount of total proanthocyanidins in the PPE (81.01 ± 0.21 mg TAE.g-1DW). CCl4 injection induced significant reductions in hepatic antioxidants but increased hepatic lipid peroxidation (LPO) as well as serum injury biomarkers. However, cotreatment with PPE significantly (P < 0.05) inverted CCl4-induced increase in plasma alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase activities, respectively to 74%, 77%, 60%, and 82% compared with CCl4 group. No significant toxic effects were observed following treatment with plant extract alone. PPE cotreatment also decreased significant (P < 0.05) the hepatic malondialdehyde formation (21%) and enhanced the liver catalase activity (107%) in CCl4-intoxicated rats. The histopathological examination showed inflammatory infiltration and degenerative changes in the hepatic tissue following CCl4 injection. The hepatoprotective activity of PPE against CCl4 exposure was supported by the maintenance of structural integrity of liver histopathology. In conclusion, the current study illustrated that PPE pretreatment significantly improved all examined parameters, restored the hepatic architecture and successfully alleviates oxidative damage induced by CCl4 intoxication.

Metabolic profiling revealed the organ-specific distribution differences of tannins and flavonols in pecan

Carya illinoinensis is rich in phenolic metabolites such as tannins and flavonols, but both the composition and the distribution of these nutritional constituents in most pecan organs were still unclear. In this experiment, a comprehensive qualification and quantification of phenolic metabolites in eight organs of pecan were conducted for the first time. Ninety-seven phenolic metabolites were identified, in which twelve were identified for the first time in pecan, including a series of ellagitannins with high molecular weight. Hydrolysable tannin was the dominant kind of phenolic metabolites in pecan. The metabolic profiles of tannins in pecan were extended. Thirty-three phenolic metabolites were quantified, among them the highest content was ellagic acid pentose in testa. From this experiment, we can see that the distribution of phenolic metabolites in pecan was organ-specific, tannins tend to accumulate in pecan testa with both diverse structures and high contents, while flavonols tend to accumulate in organs such as branch, bark, or leaf. Among all organs, testa contained the highest content of phenolics, which might play important roles in protecting pecan kernel from diseases and insects. A massive phenolic metabolites' matrix in different pecan organs was built in this experiment, which should be useful for related researches in the future and help provide a theoretical basis for using these organs as functional foods.

Chemical composition and oxidative stability of eleven pecan cultivars produced in southern Brazil

Nuts are considered highly nutritious foods and a source of health-promoting compounds. Therefore, the aim of this study was to evaluate the chemical composition (proximate composition, fatty acids, volatile compounds, total phenolics, squalene, and β-sitosterol) of eleven pecan cultivars harvested in Rio Grande do Sul State (Brazil) and investigate their oxidative stability by the Rancimat method. 'Barton' is the main cultivar produced in Brazil and presented the highest protein, linoleic acid, and linolenic acid values and the lowest saturated fatty acid values, which provide health benefits. 'Mahan' showed the highest oxidation induction time, both in extracted oil and ground samples, low abundance of lipid oxidation compounds, low polyunsaturated fatty acids, high levels of oleic acid and β-sitosterol, which suggests potential for storage. 'Stuart' and 'Success' had the highest total dietary fiber values. Moreover, analysis showed that 'Chickasaw' and 'Success' had large quantities of compounds correlated to lipid oxidation, suggesting low stability for long-term storage. These results imply that the physicochemical characteristics and proximate composition of pecan nut cultivars from southern Brazil have variable parameters that may depend on their genetic variability.

Pecan (Carya illinoinensis (Wagenh.) K. Koch) Nut Shell as an Accessible Polyphenol Source for Active Packaging and Food Colorant Stabilization

Herein, the antioxidant and food stabilizing properties of a pecan nut shell (PNS) hydroalcoholic extract (PNSE) are reported. Chemical degradation of PNSE demonstrated the presence of condensed tannins as the main phenolic components. PNSE showed remarkable antioxidant properties in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay (EC₅₀ = 0.004 mg/mL). PNSE was initially tested as an inhibitor of mushroom tyrosinase, exhibiting a quite low IC₅₀ value (0.055 mg/mL) against the enzyme diphenolase activity, suggesting its use in enzymatic browning inhibition. The anthocyanin stabilization properties were evaluated under accelerated aging conditions of both pure pigments and commercial fruit juices, and PNSE was found to be effective at concentrations (0.05 mg/mL) at which well-known stabilizers such as chlorogenic and ferulic acids proved to fail. PNSE also performed well in the stabilization of spray-dried anthocyanins for use as a food colorant, increasing the half-life of blackberry anthocyanins up to 20%. In order to explore the possibility of using PNSE as a functional additive for active packaging, polylactic acid (PLA) films containing PNSE were prepared by solvent casting, and no substantial alteration of the mechanical properties was found on addition of the extract up to 10% w/w. The films showed remarkable antioxidant properties (DDPH reduction >60% with a 3% w/w loading, at a dose of 1 mg/mL in the DPPH solution) and delayed the onset of browning of apple smoothies (ca. 30% inhibition with a 10% w/w loading). These results highlight the exploitation of PNS as a low-cost polyphenol source for food industry applications.

The potential of the pecan nut cake as an ingredient for the food industry

Pecan nut [Carya illinoinensis (Wangenh.) K. Koch] cake (PNC) is a co-product from the oil extraction industry and its potential as an ingredient for the food industry are not well known. In this work, the nutritional composition and the functional properties of PNC were studied. Additionally, the influence of different solvents (ethanol, water, and acetic acid) on the phytochemical composition and antioxidant capacity (reducing potential of the hydrophilic compounds - RPHC, 2,2-diphenyl-1-picrylhydrazyl - DPPH, and total reducing capacity - TRC) of PNC extracts were established using a simplex-centroid design. PNC is a source of carbohydrates, protein, and dietary fiber (40.5; 21.87 and 13.01 g 100 g^-1, respectively). The PNC exhibited a low energy value when compared to the raw nut (398.8 kcal 100 g^-1 and 645.54 kcal 100 g^-1, respectively). Mg, Mn and Co (416.74; 23.21 mg 100 g^-1 and 59.00 μg 100 g^-1, respectively) were the main minerals identified in PNC. The PNC also presented functional properties such as emulsifying and oil absorption capacities and a great ability to absorb water. Using the proposed solvent mixture system, the content of total phenolic compounds and condensed tannins recovered from PNC ranged between 172.43 and 2744.24 mg GAE 100 g^-1, and 253.42 to 1376.44 mg CE 100 g^-1, respectively. The antioxidant capacity of the PNC extract was showed through its ability to reduce hydrophilic (172.06-1714.96 mg GAE 100 g^-1) to transfer hydrogen atoms (12.55-74.11% scavenging activity) and lipophilic compounds (509.87-2070.80 mg QE 100 g^-1) using RPHC, DPPH, and TRC methods, respectively. Combining ethanol, water, and acetic acid at 30 °C for 15 min, positively affects the extraction of bioactive compounds from PNC, as well as the antioxidant activity of the extracts. The physicochemical, functional, phytochemical, and antioxidant properties demonstrate that pecan nut cake may represent a potential ingredient or additive for the food, pharmaceutical, and cosmetic industries.

In Vitro Antioxidant Activity Optimization of Nut Shell (Carya illinoinensis) by Extrusion Using Response Surface Methods

The pecan (Carya illinoinensis) nut shell is an important byproduct of the food processing industry that has not been previously explored as an antioxidant compound. This work aims to study the effect of the extrusion temperature and screw speed on the moisture content, water and oil absorption index, water solubility index, color, phenolic compounds, condensed tannin compounds, and antioxidant activity of pecan nut shell extrudates. Extrusion variables were adjusted using a response surface methodology. Extrusion, performed at 70 °C and 150 rpm, almost doubled the concentration of polyphenols in the non-extruded shell and significantly increased radical scavenging activity. Compounds in extrudates, performed at 70 °C and 150 rpm, were quantified by high-performance liquid chromatography (HPLC) with a diode-array detector (DAD) and identified by liquid chromatography coupled with time-of-flight mass spectrometry (LC-MSD-TOF). Extrusion significantly increased most phenolic acid compounds, including gallic acid, ellagic acid pentose, ellagic acid, dimethyl ellagic acid rhamnoside, and dimethyl ellagic acid. The soluble fiber in extrudates was more than three-fold higher than in the control. Therefore, extrusion at 70 °C and 150 rpm increased the concentration of phenolic compounds, antioxidant activity, and total dietary and soluble fiber. Our findings support the notion that extruded pecan nut shell can be used in clean-label products and improve their nutraceutical value.

Effects of Moisture, Temperature, and Salt Content on the Dielectric Properties of Pecan Kernels During Microwave and Radio Frequency Drying Processes

Dielectric properties of materials influence the interaction of electromagnetic fields with and are therefore important in designing effective dielectric heating processes. We investigated the dielectric properties (DPs) of pecan kernels between 10 and 3000 MHz using a Novocontrol broadband dielectric spectrometer in a temperature range of 5–65 °C and a moisture content range of 10–30% wet basis (wb) at three salt levels. The dielectric constant (ε′) and loss factor (ε″) of the pecan kernels decreased significantly with increasing frequency in the radio frequency (RF) band, but gradually in the measured microwave (MW) band. The moisture content and temperature increase greatly contributed to the increase in the ε′ and ε″ of samples, and ε″ increased sharply with increasing salt strength. Quadratic polynomial models were established to simulate DPs as functions of temperature and moisture content at four frequencies (27, 40, 915, and 2450 MHz), with R² > 0.94. The average penetration depth of pecan kernels in the RF band was greater than that in the MW band (238.17 ± 21.78 cm vs. 15.23 ± 7.36 cm; p < 0.01). Based on the measured DP data, the simulated and experimental temperature-time histories of pecan kernels at five moisture contents were compared within the 5 min RF heating period.

Process Optimization for Improved Phenolic Compounds Recovery from Walnut (Juglans regia L.) Septum: Phytochemical Profile and Biological Activities

Plant by-products can be valuable sources of polyphenol bioactive compounds. Walnut (Juglans regia L.) is a very important tree nut rich in biologically active molecules, but its septum was scarcely researched. Experimental data indicated a hypoglycemic effect of septum extracts, with almost no details about its phytochemical composition. The main objectives of this study were: (1) to obtain walnut septum (WS) extracts with high content in bioactive compounds and antioxidant activity based on an original experimental design; (2) characterization of the phytochemical profile of the WS extracts using HPLC-MS/MS; (3) evaluation of the biological potential of the richest polyphenolic WS extract. The variables of the experimental design were: extraction method (maceration and Ultra-Turrax extraction), temperature, solvent (acetone and ethanol), and percentage of water in the solvent. The first quantifiable responses were: total phenolic content, total flavonoid content, condensed tannins, and ABTS antioxidant capacity. The phytochemical profile of lyophilized extracts obtained by Ultra-Turrax extraction (UTE), the most efficient method, was further determined by HPLC-MS/MS analysis of individual polyphenolic and phytosterols compounds. It is the first study to assay the detailed composition of WS in hydrophilic and lipophilic compounds. The biological potential of the richest polyphenolic WS extract was also evaluated by FRAP and DPPH antioxidant capacity and the inhibition of tyrosinase, an enzyme involved in the browning in fruits and vegetables, skin wrinkles and aging. Conclusion: The phytochemical profile of the analyzed extracts proves that WS can be a valuable source of biologically active compounds (polyphenols) for food and/or pharmaceutical industry and warrant the continuation of current research in further evaluating its bioactive potential.

Dynamic Changes in Phenolics and Antioxidant Capacity during Pecan (Carya illinoinensis) Kernel Ripening and Its Phenolics Profiles

Pecan (Carya illinoinensis) kernels have a high phenolics content and a high antioxidant capacity compared to other nuts-traits that have attracted great interest of late. Changes in the total phenolic content (TPC), condensed tannins (CT), total flavonoid content (TFC), five individual phenolics, and antioxidant capacity of five pecan cultivars were investigated during the process of kernel ripening. Ultra-performance liquid chromatography coupled with quadruple time-of-flight mass (UPLC-Q/TOF-MS) was also used to analyze the phenolics profiles in mixed pecan kernels. TPC, CT, TFC, individual phenolics, and antioxidant capacity were changed in similar patterns, with values highest at the water or milk stages, lowest at milk or dough stages, and slightly varied at kernel stages. Forty phenolics were tentatively identified in pecan kernels, of which two were first reported in the genus Carya, six were first reported in Carya illinoinensis, and one was first reported in its kernel. The findings on these new phenolic compounds provide proof of the high antioxidant capacity of pecan kernels.

Fatty acid profile of pecan nut oils obtained from pressurized n-butane and cold pressing compared with commercial oils

This short note compares the chemical profile of pecan nut oil samples obtained from pressurized n-butane and cold pressing with two commercial oils. The conventional cold pressing technique yielded 58.9 wt%, while pressurized n-butane yielded from 53 to 65 wt%, being the highest yield at 55 °C, and pressure of 40 bar. The n-butane behaves nearly like a piston fluid within the experimental conditions used. The results showed that the extraction variables had a slight influence on the fatty acid composition of the samples. Extraction with n-butane thus showed to be a promising alternative technique to conventional extraction methods, as very mild operating conditions and eco-friendly solvent can be used to provide good results without any residues in the final product.

Hypoglycemic and antihyperglycemic effects of phytopreparations and limonoids from Swietenia humilis

An aqueous extract from the seeds of Swietenia humilis (31.6-100mg/kg bw) lowered (p<0.05) blood glucose levels in normal and nicotinamide-streptozotocin (NA-STZ)-induced hyperglycemic mice. Furthermore, when administered to fructose-fed rats with metabolic syndrome, the decoction showed significant antihyperglycemic, hypoglycemic and hypolipidemic effects, as well as an augmentation of hepatic glycogen. Limonoids 2-hydroxy-destigloyl-6-deoxyswietenine acetate (1), humulin B (2), methyl-2-hydroxy-3-β-isobutyroxy-1-oxomeliac-8(30)-enate (3), methyl-2-hydroxy-3-β-tigloyloxy-1-oxomeliac-8(30)-enate (4), humilinolide G (5), humilinolide C (6), methyl-2-hydroxy-3-β-isobutyoyl-8α,30α-epoxy-1-oxo-meliacate (7), and humilinolide H (8), were isolated from a CH2Cl2-MeOH (1:1) extract of the seeds. Compounds 5 and 8 are analogs of compounds 6 and 7. The structure of 5 was unequivocally established by X-ray analysis. When tested in normal and NA-STZ-hyperglycemic mice, compounds 1, 2, and 4 (3.16-31.6 mg/kg bw) decreased glycemia during an oral glucose tolerance test. The present investigation sustains the contemporary popular uses of S. humilis seeds for treating metabolic disorders, including diabetes and dyslipidemia and demonstrates the potential of the mexicanolides as antihyperglycemic agents.

The pecan nut (Carya illinoinensis) and its oil and polyphenolic fractions differentially modulate lipid metabolism and the antioxidant enzyme activities in rats fed high-fat diets

Tree nuts such as pecans (Carya illinoinensis) contain mostly oil but are also a source of polyphenols. Nut consumption has been linked to a reduction in serum lipid levels and oxidative stress. These effects have been attributed to the oil while overlooking the potential contribution of the polyphenols. Because the evidence regarding each fraction's bioactivity is scarce, we administered high-fat (HF) diets to male Wistar rats, supplementing them with pecan oil (HF+PO), pecan polyphenols (HF+PP) or whole pecans (HF+WP), and analysed the effects of each fraction. The HF diet increased the serum leptin and total cholesterol (TC) with respect to the control levels. The HF+WP diet prevented hyperleptinemia and decreased the TC compared with the control. The HF+WP diet upregulated the hepatic expression of apolipoprotein B and LDL receptor mRNAs with respect to the HF levels. The HF+PO diet reduced the level of triacylglycerols compared with the control. The HF+PP diet stimulated the hepatic expression of liver X receptor alpha mRNA. The HF+WP diet increased the activities of hepatic catalase, glutathione peroxidase and glutathione S transferase compared with the control, and decreased the degree of lipid peroxidation compared with the HF diet. The most bioactive diet was the WP diet.