Debittering of bitter gourd juice using β-cyclodextrin: Mechanism and effect on antidiabetic potential

Evaluate the effect of β-cyclodextrin on the sensory and physicochemical properties of bitter gourd extract during thermal processing

This study aims to evaluate the impact of β-cyclodextrin (β-CD) on the properties of the bitter gourd extract (BGE) under various heating conditions. In this work, the BGE and BGE supplemented with β-CD (0.75%) were heated at 60, 90, and 121 °C for 20 min before measuring the changes of bitterness, total saponin, polyphenol, antioxidant capacity, free amino acid, 5-hydroxymethylfurfural, browning intensity, and pH. It was found that β-CD mitigated the effect of heat treatment on the BGE, especially on saponins and color. Results also showed the debittering ability of β-CD was still preserved after heating duration. The bitter-masking and defensive mechanism of β-CD was also demonstrated using FTIR, thermogravimetric analysis, and molecular docking stimulation. These findings illustrated the addition of β-CD improved the thermal stability of the BGE, opening up the opportunities to incorporate BGE, which is promising in diabetes treatment but thermolabile, into heat-processed products.

Optimization of limonin invertase production by scaling up Aspergillus tubingensis UA13 fermentation to a 5-l scale

The enzymatic approach is a highly effective and the major scientific method to eliminating bitter components in citrus-derived products nowadays. Microbial production of limonin invertase stands out due to its pivotal role in the removal of the bitter substance, limonin. The optimization of fermentation parameters and the study of scale-up fermentation are imperative for product commercialization. In this study, we focused on optimizing stirring speed, fermentation temperature, and initial pH to enhance the growth and limonin invertase production by the Aspergillus tabin strain UA13 in a 5-l stirred-tank bioreactor. Our results revealed the following optimal parameters are: a stirring speed of 300 rpm, a fermentation temperature of 35°C and a pH 5.0. Under these optimized conditions, the limonin invertase activity reached its peak at 63.38 U ml-1, representing a 1.67-fold increase compared to the unoptimized conditions (38.10 U ml-1), while also reducing the fermentation duration by 12 h. Furthermore, our research demonstrated that limonin invertase effectively hydrolyze limonin in grapefruit juice, reducing its content from 13.28 to 2.14 μg ml-1, as determined by HPLC, resulting in a 6.21-fold reduction of the bitter substance.

New opportunities for cyclodextrins in supramolecular assembly: metal organic frameworks, crystalline self-assembly, and catalyzed assembly

Cyclodextrins (CDs) are widely used macrocycles in supramolecular assembly due to their easy availability, versatile functionality and excellent biocompatibility. Although they are well-known for forming host-guest complexes with a wide range of guests and this host-guest chemistry has long been utilized in industry and academia, new opportunities have arisen in recent years, particularly in supramolecular assembly. In the present review, we will first provide a basic introduction to CDs and then summarize their emerging roles in the fields of supramolecular chemistry and materials. This includes their involvement in hybrid frameworks with inorganic components such as metal ions and polyoxometalates, crystalline self-assembly with amphiphilic molecules, and their new possibility of "catassembly" and induced chiral supramolecular structures that have previously been overlooked. Finally, we will comment on the future perspectives of CDs to inspire more ideas and efforts, with the aim of promoting diverse applications of CDs in supramolecular materials.

New insights into anti-diabetes effects and molecular mechanisms of dietary saponins

Diabetes mellitus (DM) is a long-term metabolic disorder that manifests as chronic hyperglycemia and impaired insulin, bringing a heavy load on the global health care system. Considering the inevitable side effects of conventional anti-diabetic drugs, saponins-rich natural products exert promising therapeutic properties to serve as safer and more cost-effective alternatives for DM management. Herein, this review systematically summarized the research progress on the anti-diabetic properties of dietary saponins and their underlying molecular mechanisms in the past 20 years. Dietary saponins possessed the multidirectional anti-diabetic capabilities by concurrent regulation of various signaling pathways, such as IRS-1/PI3K/Akt, AMPK, Nrf2/ARE, NF-κB-NLRP3, SREBP-1c, and PPARγ, in liver, pancreas, gut, and skeletal muscle. However, the industrialization and commercialization of dietary saponin-based drugs are confronted with a significant challenge due to the low bioavailability and lack of the standardization. Hence, in-depth evaluations in pharmacological profile, function-structure interaction, drug-signal pathway interrelation are essential for developing dietary saponins-based anti-diabetic treatments in the future.

The effect of carboxymethyl cellulose and β-cyclodextrin as debittering agents on bitterness and physicochemical properties of bitter gourd extract

Bitter gourd extract (BGE) is rich in antioxidants and anti-diabetic components that promote good human health; however, its bitter taste makes it challenging to use in food. In this study, the effect of carboxymethyl cellulose and β-cyclodextrin (β-CD) on the bitterness and properties of BGE were investigated. The bitterness intensity was evaluated by the trained sensory panel, and the physicochemical properties were also determined, including viscosity, total saponin, polyphenol content, antioxidant capacity, and α-amylase inhibition activity. It was found that the bitterness of BGE with 0.75%, w/v β-cyclodextrin decreased significantly by more than 90%. Additionally, FTIR, 1 H-NMR, and thermogravimetric analysis of BGE supplemented with β-CD confirmed the formation of a complex between β-CD and components of BGE. The findings of the current study also reveal that debittering agents did not inhibit the bioactivities of BGE.

Debittering of Grape Juice by Electrospun Nylon Nanofibrous Membranes: Impact of Filtration on Physicochemical, Functional, and Sensory Properties

The effect of electrospun nylon-6 nanofibrous membranes (NFMs) on the concentration of bitter compounds and antioxidants of grapefruit juices during dead-end filtration processes was studied. Filtration experiments with aqueous standard solutions of different molecules showed that NFMs retain low molecular weight antioxidants (i.e., ascorbic and caffeic acids) only at early filtration stages, whereas they remove bitter glycosylated phenolics (i.e., naringin and narirutin) at a more stable ratio, variable according to the membrane thickness. Experiments with fresh grapefruit juice of two varieties (pink and yellow) showed that NFM-filtration reduces (17 to 30%) flavanones associated with the immediate bitterness and allows for the complete removal (>99.9%) of limonin, responsible for the persistent bitterness of many citrus juices. In contrast, the same process causes a lower loss of ascorbic acid (5%) and does not affect acidity, nor sugar concentration. The results confirmed that NFMs feature permselectivity towards bitterness-related compounds. This work highlights the NFM potential as filter devices for the selective reduction of the bitter terpenoid (limonin) and glycosylated flavonoids (naringin and narirutin) from grape juice citrus juices in the production of industrially-relevant beverages.

Biosynthesis, distribution, nutritional and organoleptic properties of bitter compounds in fruit and vegetables

Compounds that confer a bitter taste on fruits and vegetables (FAVs) play crucial roles in both plant defense and health promotion. This review details the current knowledge of the distribution, properties (toxicity, pharmacological effects and receptors) and environmental plant responses relating to the biosynthesis, catabolism and transcriptional regulation of 53 bitter plant metabolites in diverse species of FAVs. Some bitter compounds, such as flavonoids, are common in all plant species and make a minor contribution to bitter flavor, but many are synthesized only in specific taxa. They make major contributions to the bitter taste of the corresponding species and some also have significant pharmacological effects. Levels of bitter metabolites are genetically determined, but various environmental cues can affect their final concentration during preharvest development and postharvest storage processes. Molecular approaches are helping to unravel the mechanisms of biosynthesis and regulation of bitter compounds in diverse crop species. This review not only discusses the theoretical basis for utilizing breeding programs and other agricultural technologies to produce FAVs with improved safety, favorable taste and healthier profiles, but also suggests new directions for the utilization of bitter compounds in FAVs for the development of natural pesticides and health-promoting medicines.

Stability, Antioxidant Activity and Intestinal Permeation of Oleuropein Inclusion Complexes with Beta-Cyclodextrin and Hydroxypropyl-Beta-Cyclodextrin

Compared to beta-cyclodextrins (beta-CD), hydroxypropyl-beta-cyclodextrins (HP-beta-CD) are a more popular material used to prepare inclusion complexes due to their superior solubility and intestinal absorption. In this study, oleuropein (OL) inclusion complexes with beta-CD (beta-CD:OL) and HP-beta-CD (HP-beta-CD:OL) were prepared and the formation of inclusion complexes was validated by IR, PXRD, and DSC. A phase solubility test showed that the lgK (25 °C) and binding energy of beta-CD:OL and HP-beta-CD:OL was 2.32 versus 1.98, and −6.1 versus −24.66 KJ/mol, respectively. Beta-CD:OL exhibited a more powerful effect than HP-beta-CD:OL in protecting OL from degradation upon exposure to light, high temperature and high humidity. Molecular docking, peak intensity of carbonyls in IR, and ferric reducing power revealed that beta-CD:OL formed more hydrogen bonds with the unstable groups of OL. Both inclusion complexes significantly enhanced the solubility, intestinal permeation and antioxidant activity of OL (p < 0.05). Though HP-beta-CD:OL had higher solubility and intestinal absorption over beta-CD:OL, the difference was not significant (p > 0.05). The study implies that lower binding energy is not always associated with the higher stability of a complex. Beta-CD can protect a multiple-hydroxyl compound more efficiently than HP-beta-CD with the intestinal permeation comparable to HP-beta-CD complex.

Recent advances in cyclodextrin-based films for food packaging

Cyclodextrins are garnering increasing attention because they offer several benefits. For instance, cyclodextrins can form several complexes and supramolecular structures not only for food packaging but also for applications in other fields of science. In this review, we discussed the physical and chemical properties of cyclodextrins and the mechanism of their inclusion complex formation. The use of cyclodextrins in various types of food packaging is elaborated upon. We also explain the effects of cyclodextrins on the packaging of fruits, vegetables, meat, fish, and processed foods. Furthermore, some feasible suggestions for future applications are provided. In addition to the positive attributes of cyclodextrins, there are some limitations and drawbacks, which are discussed briefly in this review. In summary, this review can serve as a guide for researchers exploring cyclodextrins for the development of various packaging films.

The Role of Cyclodextrins in the Design and Development of Triterpene-Based Therapeutic Agents

Triterpenic compounds stand as a widely investigated class of natural compounds due to their remarkable therapeutic potential. However, their use is currently being hampered by their low solubility and, subsequently, bioavailability. In order to overcome this drawback and increase the therapeutic use of triterpenes, cyclodextrins have been introduced as water solubility enhancers; cyclodextrins are starch derivatives that possess hydrophobic internal cavities that can incorporate lipophilic molecules and exterior surfaces that can be subjected to various derivatizations in order to improve their biological behavior. This review aims to summarize the most recent achievements in terms of triterpene:cyclodextrin inclusion complexes and bioconjugates, emphasizing their practical applications including the development of new isolation and bioproduction protocols, the elucidation of their underlying mechanism of action, the optimization of triterpenes’ therapeutic effects and the development of new topical formulations.

Jayaprakasha G, S. Patil B. Anti-Inflammatory, Antidiabetic Properties and In Silico Modeling of Cucurbitane-Type Triterpene Glycosides from Fruits of an Indian Cultivar of Momordica charantia L

Diabetes mellitus is a chronic disease and one of the fastest-growing health challenges of the last decades. Studies have shown that chronic low-grade inflammation and activation of the innate immune system are intimately involved in type 2 diabetes pathogenesis. Momordica charantia L. fruits are used in traditional medicine to manage diabetes. Herein, we report the purification of a new 23-O-β-d-allopyranosyl-5β,19-epoxycucurbitane-6,24-diene triterpene (charantoside XV, 6) along with 25ξ-isopropenylchole-5(6)-ene-3-O-β-d-glucopyranoside (1), karaviloside VI (2), karaviloside VIII (3), momordicoside L (4), momordicoside A (5) and kuguaglycoside C (7) from an Indian cultivar of Momordica charantia. At 50 µM compounds, 2–6 differentially affected the expression of pro-inflammatory markers IL-6, TNF-α, and iNOS, and mitochondrial marker COX-2. Compounds tested for the inhibition of α-amylase and α-glucosidase enzymes at 0.87 mM and 1.33 mM, respectively. Compounds showed similar α-amylase inhibitory activity than acarbose (0.13 mM) of control (68.0–76.6%). Karaviloside VIII (56.5%) was the most active compound in the α-glucosidase assay, followed by karaviloside VI (40.3%), while momordicoside L (23.7%), A (33.5%), and charantoside XV (23.9%) were the least active compounds. To better understand the mode of binding of cucurbitane-triterpenes to these enzymes, in silico docking of the isolated compounds was evaluated with α-amylase and α-glucosidase.

Potential risks of nicotine on the germination, growth, and nutritional properties of broad bean

This study evaluated the allelopathy, uptake and accumulation, and potential agricultural and food safety risks of nicotine in broad bean (Vicia faba L.) during seed germination and seedling growth. Nicotine stress has an allelopathic inhibitory effect on seeds and a hormesis effect on germinated seeds and seedlings, which has an enhancement effect (<50 mg kg^-1) and an inhibition effect (>100 mg kg^-1) on the germinated seeds and an enhancement effect (<100 mg kg^-1) and an inhibition effect (>200 mg kg^-1) on the seedlings. Exogenous nicotine can be absorbed by broad bean roots from nicotine-contaminated soil and accumulated in the main organs of the seedlings, especially the leaves, which exceeded the maximum residue level (0.03 mg kg^-1 DW) at 50 mg kg^-1. Moreover, nicotine resulted in a bitter taste in the edible broad bean leaves, disrupting the balance of basic nutritional properties, decreasing sucrose, and increasing bitter substances such as choline and procyanidin. These results demonstrated that residual nicotine in the soil not only poses potential risks to sustainable agricultural development but also a food safety risk for consumers. The present study provides insight into the potential risks of nicotine in agroecosystems.

Green Extracts from Coffee Pulp and Their Application in the Development of Innovative Brews

Coffee pulp, a by-product of coffee production, contains valuable compounds such as caffeine and chlorogenic acid with high antiradical activity. In this study, aqueous solutions of β-cyclodextrin (β-CD) were used as a non-conventional solvent for the extraction of targeted compounds from coffee pulp. The parameters of β-CD concentration (Cβcd), liquid-to-solid ratio (L/S), and temperature (T) were evaluated based on the antiradical activity (AAR) and the caffeine content (CCaf). The optimum operational conditions were found to be Cβcd: 9.25 mg/mL, L/S: 30 mL/g and T: 80 °C. The sensory profiles of brews prepared with coffee and coffee pulp with or without cyclodextrin were studied with quantitative descriptive analysis. The brew from the by-product had fruity, botanic, sweet and sourness sensory properties, and cyclodextrin was found to be able to affect the overall taste of the brew.

Quantitative prediction of the bitterness of atomoxetine hydrochloride and taste-masked using hydroxypropyl-β-cyclodextrin: A biosensor evaluation and interaction study

The bitterness of a drug is a major challenge for patient acceptability and compliance, especially for children. Due to the toxicity of medication, a human taste panel test has certain limitations. Atomoxetine hydrochloride (HCl), which is used for the treatment of attention deficit/hyperactivity disorder (ADHD), has an extremely bitter taste. The aim of this work is to quantitatively predict the bitterness of atomoxetine HCl by a biosensor system. Based on the mechanism of detection of the electronic tongue (E-tongue), the bitterness of atomoxetine HCl was evaluated, and it was found that its bitterness was similar to that of quinine HCl. The bitterness threshold of atomoxetine HCl was 8.61 µg/ml based on the Change of membrane Potential caused by Adsorption (CPA) value of the BT0 sensor. In this study, the taste-masking efficiency of 2-hydroxypropyl-β-cyclodextrin (HP-β-CyD) was assessed by Euclidean distances on a principle component analysis (PCA) map with the SA402B Taste Sensing System, and the host-guest interactions were investigated by differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM). Biosensor evaluation and characterization of the inclusion complex indicated that atomoxetine HCl could actively react with 2-hydroxypropyl-β-cyclodextrin.

Purification, characterization, and hypoglycemic properties of eurocristatine from Eurotium cristatum spores in Fuzhuan brick tea

Fuzhuan brick tea (FBT) is a Chinese dark tea that is famous for its significant health benefits, in which Eurotium cristatum (E. cristatum) strains play a vital role in its postfermentation process. In this study, eurocristatine with hypoglycemic activity was discovered for the first time and purified from the spores of E. cristatum growing in FBT. Eurocristatine (98%) was obtained by D-101 macroporous resin-based column chromatography and preparative high performance liquid chromatography (HPLC) with a C18 column as the stationary phase and 35% acetonitrile in ultrapure water as the mobile phase. Hypoglycemic activity in a Hep-G2 cell hypoglycemic model was used as a screening indicator during purification. The chemical structure of eurocristatine was characterized by ESI/MS, 1H NMR and 13C NMR analyses. The antidiabetic effects of eurocristatine were verified in high-fat diet/streptozocin-induced type 2 diabetes mellitus (T2DM) rats. The results showed that eurocristatine significantly reduced fasting blood glucose. Our study demonstrated that eurocristatine, as a newly discovered hypoglycemic active substance, could be considered a potential candidate for the treatment of diabetes and its complications.

High Dietary Kuding Tea Extract Supplementation Induces Hepatic Xenobiotic-Metabolizing Enzymes-A 6-Week Feeding Study in Mice

Kuding tea (KT) is a traditional Chinese beverage rich in plant bioactives that may exhibit various health benefits. However, little is known about the safety of KT extract (KTE) when consumed long term at high doses as a dietary supplement. Therefore, in this study, we investigated aspects of the safety of KTE. Male C57BL/6 mice were fed a high-fat, high-fructose, Western-type diet (control) supplemented with either 12.88% γ-cyclodextrin (γCD), 7.12% KTE (comprising 0.15% ursolic acid, UA) encapsulated in 12.88% γCD (KTE-γCD), or 0.15% UA over a 6-week experimental period. The dietary treatments did not affect food intake, body weight or body composition. However, treatment with KTE-γCD, but not γCD and UA, increased liver weight and hepatic fat accumulation, which was accompanied by increased hepatic PPARγ and CD36 mRNA levels. KTE-γCD treatment elevated plasma cholesterol and CYP7A1 mRNA and protein levels compared to those in control mice. KTE-γCD substantially increased the mRNA and protein levels of hepatic CYP3A and GSTA1, which are central to the detoxification of drugs and xenobiotics. Furthermore, we observed a moderate elevation in hepatic CYP3A (5-fold change) and GSTA1 (1.7-fold change) mRNA levels in UA-fed mice. In vitro data collected in HepG2 cells indicated a dose-dependent increase in hepatic cytotoxicity in response to KTE treatment, which may have been partly mediated by UA. Overall, the present data may contribute to the safety assessment of KTE and suggest that KTE encapsulated in γCD affects liver fat storage and the hepatic phase I and phase II responses in mice.

Influence of different pasteurization techniques on antidiabetic, antioxidant and sensory quality of debittered bitter gourd juice during storage

Debittered bitter gourd juice was subjected to gamma irradiation doses of 0, 0.25, 0.5, 0.75, 1, 1.5 and 2.5 kGy and thermal pasteurization at temperatures of 65, 75, 85 and 95 °C. Shigella boydii was the most heat resistant pathogen tested (D₁₀ of 42.8 s at 65 °C) while Bacillus cereus was the most resistant pathogen to irradiation with a D₁₀ of 0.46 kGy. No significant (p < 0.05) effect of thermal pasteurization was observed on antidiabetic (α-amylase and α-glucosidase inhibition) activity, however, a 10% increase in α-glucosidase inhibition was observed in irradiated (2.5 kGy) samples. A significant (p < 0.05) but marginal reduction (up to 10%) was observed in antidiabetic activity during storage for a period of 90 days. Thermal pasteurization at 65 °C demonstrated significantly (p < 0.05) higher sensory quality as compared to irradiated (2.5 kGy) samples. This is first report on effect of pasteurization on antidiabetic activity of bitter gourd juice.