Extract‐rich in flavonoids from Hibiscus sabdariffa calyces: Optimizing microwave‐assisted extraction method and characterization through LC‐Q‐TOF‐MS analysis

Phytochemical and antibacterial properties of calyces Hibiscus sabdariffa L.: an in vitro and in silico multitarget-mediated antibacterial study

BACKGROUND

Multidrug-resistant (MDR) bacteria pose a significant threat to human health worldwide by increasing the harmful impact of traditional synthetic antibiotics. Traditional medicinal plants have bioactive metabolites that can significantly modulate the growth rate, cell survival, and pathogenicity of antibiotic-resistant bacteria. Hibiscus sabdariffa L., known as Roselle or Karkade, belongs to the Malvaceae family. It is well-known for its edible aromatic red/purple calyces and is extensively utilized in the food industry and pharmacological applications. H. sabdariffa calyx bioactive phytocompounds have potent therapeutic activities such as antimicrobial, antidiabetic, antiobesity, antioxidant, anti-inflammatory, and anticancer properties.

METHODS

This study utilized gas chromatography-mass spectrometry (GC-MS) analysis to determine the volatile aromatic compounds that found in the hydroethanolic extract of Hibiscus sabdariffa calyces. The purpose was to verify the antibacterial properties of Roselle calyces against selective MDR clinical bacterial isolates, including A. baumanii, E. coli, K. pneumoniae, and P. aeruginosa.

RESULTS

The GC-MS spectrum profile revealed the presence of twenty-seven volatile organic components, including organic fatty acid derivatives, ester compounds, sugar derivatives, and terpene components. The major GC-MS fractionations and the main active chemical compositions of the hydroethanolic extract of H. sabdariffa flowers were (E)-10-Octadecenoic acid methyl ester (59.23%), 8,11-Octadecadienoic acid, methyl ester (11.51%), Butanedioic acid, 3-hydroxy-2,2-dimethyl-, diethyl ester (6.22%), Diethyl succinate/Butanedioic acid, diethyl ester (2.35%), and Heptadecanoic acid, 16-methyl-, methyl ester/Methyl isostearate (2.31%). The hydroethanolic extract of H. sabdariffa dried calyces demonstrated potent antibacterial properties (zones diameter of inhibition growth, MIC, MBC, and MBC/MIC) against selective MDR clinical bacterial isolates, such as A. baumanii, E. coli, K. pneumoniae, and P. aeruginosa, as determined by the phytochemical screening (TAC, TFC, and TPC) and antioxidant activity (DPPH). The surface morphological characteristics of the treated A. baumanii, E. coli, K. pneumoniae, and P. aeruginosa clinical isolates have been affected in comparison to the untreated forms by the hydroethanolic extract of H. sabdariffa calyces, as determined by scanning electron microscopy (SEM). In silico predictive investigation revealed that the volatile aromatic components of the hydroethanolic extract of Roselle calyces exhibited significant scoring functions, binding affinities, and non-covalent intermolecular interactions with the MenB lyase and DNA gyrase targets of E. coli. These interactions significantly enhanced the activities of the volatile aromatic components against the bacterial pathogenicity, cell survival, growth, and differentiation of selective MDR clinical bacterial isolates.

CONCLUSIONS

According to the in vitro and in silico findings, the hydroethanolic extract of H. sabdariffa calyces has shown potentials as an effective antioxidant and antibacterial treatment. It contains volatile aromatic compounds that can modulate selective MDR Gram-negative clinical bacterial isolates.

Circular Bioeconomy in Action: Transforming Food Wastes into Renewable Food Resources

The growing challenge of food waste management presents a critical opportunity for advancing the circular bioeconomy, aiming to transform waste into valuable resources. This paper explores innovative strategies for converting food wastes into renewable food resources, emphasizing the integration of sustainable technologies and zero-waste principles. The main objective is to demonstrate how these approaches can contribute to a more sustainable food system by reducing environmental impacts and enhancing resource efficiency. Novel contributions of this study include the development of bioproducts from various food waste streams, highlighting the potential of underutilized resources like bread and jackfruit waste. Through case studies and experimental findings, the paper illustrates the successful application of green techniques, such as microbial fermentation and bioprocessing, in valorizing food wastes. The implications of this research extend to policy frameworks, encouraging the adoption of circular bioeconomy models that not only address waste management challenges but also foster economic growth and sustainability. These findings underscore the potential for food waste to serve as a cornerstone in the transition to a circular, regenerative economy.

Modulation of the Hyperglycemia Condition in Diabetic Lab Rats with Extracts of the Creole Jamaica Flower (Hibiscus sabdariffa L.) from the Morelia Region (Mexico)

Extracts from Jamaica flowers (Hibiscus sabdariffa) from Morelia (Mexico) were evaluated as antidiabetic ingredients in a diabetic rat lab model for 80 days at doses of 200, 400, and 600 mg extract/kg rat weight. The hydroalcoholic extract (water:ethanol 80:20 (v/v) at 50 °C) showed a TPC value of 403.28 ± 7.71 mg GAE/g extract, and an antioxidant activity of 0.219 ± 0.00003 mmol Trolox/g (ABTS) and 0.134 ± 0.00001 mmol Trolox/g (DPPH). The extract allowed reducing the diabetic glucose plasma levels under fasting conditions in a dose-dependent manner by 35.2%, 41.63%, and 50.1%. Additionally, the highest dose of the extract (600 mg/kg) slightly reduced the short-term postprandial glucose response while improving the long-term response, reducing hyperglycemia by 45.1%. The same dose also improved lipid metabolism by reducing total cholesterol, triglycerides, VLDL, and LDL, while the HDL level increased. The improvement in glucose and lipid management in the treated groups also led to reduced levels of glycosylated hemoglobin, as well as lower insulin resistance (TyG index), compared to the diabetic control group. The results of this study suggest that extracts from Hibiscus sabdariffa (Morelia) can be used as potential functional ingredients or nutraceuticals for managing the diabetic condition.

Production of a novel laccase from Ceratorhiza hydrophila and assessing its potential in natural dye fixation and cytotoxicity against tumor cells

BACKGROUND

Flavonoid natural dyes have gained attention because they are nontoxic and eco-friendly. However, they do not work effectively with artificial fibers and require the use of mordants, which are considered as hazardous chemicals. Laccase enzyme catalyzes the oxidation of phenols, forming phenoxyl radicals that undergo a further polymerization process. So, laccase can oxidize flavonoid dyes, and it can be used instead of harmful mordants in flavonoid dye fixation on cotton fabrics. Laccases also are involved in a variety of metabolic processes, and they have anti-proliferative effects toward HepG2 and MCF-7 tumor cells.

RESULTS

Among fifteen fungal isolates, the fungus Ceratorhiza hydrophila isolated from the submerged plant Myriophyllum spicatum was selected as the most potent laccase producer. Optimization of the production medium resulted in a 9.9-fold increase in laccase productivity. The partially purified Ceratorhiza hydrophila laccase could successfully improve the affinity of cotton fabrics toward quercetin (flavonoid) dye with excellent color fastness properties. The partially purified laccase also showed anti-proliferative activity against HepG2 and MCF-7 tumor cells. However, high laccase concentration is required to estimate IC50.

CONCLUSIONS

Ceratorhiza hydrophila MK387081 is an excellent laccase producer. The partially purified laccase from Ceratorhiza hydrophila can be used in textile dyeing and printing processes as a safer alternative to the conventional hazardous mordants. Also, it can be used in preparation of cancer treatment drugs. However, further studies are needed to investigate IC50 for both cell types at higher laccase concentrations.

Serum Phospholipids Are Potential Therapeutic Targets of Aqueous Extracts of Roselle (Hibiscus sabdariffa) against Obesity and Insulin Resistance

Roselle (Hibiscus sabdariffa) is rich in phenolic compounds with antiobesogenic and antidiabetic effects. In this study, the effects of aqueous extracts of two varieties of Hibiscus sabdariffa, Alma blanca (white-yellow color) and Cuarenteña (purple color), were evaluated for the prevention of obesity and insulin resistance in rats fed a high-fat and high-fructose diet (HFFD), identifying targeted molecules through global metabolomics. After sixteen weeks, both roselle aqueous extracts prevented body weight gain, and white roselle extract ameliorated insulin resistance and decreased serum free fatty acid levels. Moreover, white roselle extract decreased 18:0 and 20:4 lysophosphatidylethanolamines and purple roselle extract increased 16:0 and 20:4 lysophosphatidylinositol compared to HFFD-fed rats. These results demonstrate that roselle's beneficial health effects are variety-dependent. Interestingly, the white roselle extract showed a greater beneficial effect, probably due to its high contents of organic and phenolic acids, though its consumption is not as popular as that of the red/purple varieties.

Encapsulation of bioactive compounds extracted from plants of genus Hibiscus: A review of selected techniques and applications

The genus Hibiscus includes more than 250 species, and many studies showed that these plants contain bioactive compounds with technological potential to be used in the development of functional foods. However, the instability of these compounds during typical food processing conditions, such as exposure to high temperatures, pH changes and presence of light and oxygen have stimulated the use of encapsulation techniques to increase their stability and applicability. Among the existing Hibiscus species, only H. sabdariffa, H. cannabinus, and H. acetosella have been investigated in encapsulation studies, being spray drying the most common method approached. Considering the high technological potential offered by the incorporation of encapsulated bioactive compounds from plants of the genus Hibiscus in food formulations, this review discusses key information of selected encapsulation techniques, which represents promising alternatives to increase food systems' stability and stimulate the design of new functional foods. Relevant gaps in the literature were also noticed, mainly the lack of systematic studies regarding the composition of bioactive compounds after encapsulation, instead of total determinations, and biological activities in different analytical systems, such as antioxidant, antimicrobial and anti-inflammatory properties as well as bioaccessibility and bioavailability.

Methodologies in the Analysis of Phenolic Compounds in Roselle (Hibiscus sabdariffa L.): Composition, Biological Activity, and Beneficial Effects on Human Health

Roselle (Hibiscus sabdariffa L.), as an edible flower, has long provided an array of positive effects on human health. This benefit is a result of phenolic compounds that are naturally present mainly in the calyx. Plentiful medicinal remedies and functional foods based on this flower are available worldwide, as supported by the studies of phenolic compounds in recent decades. This paper aims to provide a comprehensive review of the composition, biological activity, and beneficial effects on human health of phenolic compounds in roselle. This review was performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. A structured search in the published literature for phenolics compositions in roselle was required prior to the evaluation on the validity of the reported analytical methods. Reliable identification and quantification of phenolic compounds in roselle can be achieved by employing the proper extraction and separation methods. With ample alternative analytical methods discussed here, this review provided an aid for comprehending and selecting the most appropriate method for a particular study. The applications of the analytical methods highlighted indicated that phenolic acids, flavonoids, and their derivatives have been identified and quantified in roselle with a range of biological activities and beneficial effects on human health. It was also disclosed that the composition and concentration of phenolic compounds in roselle vary due to the growth factors, cultivars, and environmental influence. Finally, apart from the research progress carried out with roselle during the last ten years, this review also proposed relevant future works.

Dietary 5,6,7-Trihydroxy-flavonoid Aglycones and 1-Deoxynojirimycin Synergistically Inhibit the Recombinant Maltase-Glucoamylase Subunit of α-Glucosidase and Lower Postprandial Blood Glucose

1-Deoxynojirimycin (1-DNJ) is the major effective component of mulberry leaves, exhibiting inhibitory activity against α-glucosidase. However, due to the low content of 1-DNJ in mulberry products, its level cannot meet the lowest dose to exhibit its activity. In this study, a combination of dietary 5,6,7-trihydroxy-flavonoid aglycones with 1-DNJ showed synergistic inhibitory activity against maltase of mice α-glucosidase and recombinant C- and N-termini of maltase-glucoamylase (MGAM) and baicalein with 1-DNJ exhibited the strongest synergistic effect. The synergistic effect of the combination was also confirmed by the maltose tolerance test in vivo. Enzyme kinetics, molecular docking, fluorescence spectrum, and circular dichroism spectrometry studies indicated that the major mechanism of the synergism is that baicalein was a positive allosteric inhibitor and bound to the noncompetitive site of MGAM, causing an increase of the binding affinity of 1-DNJ to MGAM. Our results might provide a theoretical basis for the design of dietary supplements containing mulberry products.