Development of an environmentally-friendly solvent-free extraction of saffron bioactives using subcritical water

Rapid detection and quantification of adulteration in saffron by excitation-emission matrix fluorescence combined with multi-way chemometrics

BACKGROUND

Saffron has gained people's attention and love for its unique flavor and valuable edible value, but the problem of saffron adulteration in the market is serious. It is urgent for us to find a simple and rapid identification and quantitative estimation of adulteration in saffron. Therefore, excitation-emission matrix (EEM) fluorescence combined with multi-way chemometrics was proposed for the detection and quantification of adulteration in saffron.

RESULTS

The fluorescence composition analysis of saffron and saffron adulterants (safflower, marigold and madder) were accomplished by alternating trilinear decomposition (ATLD) algorithm. ATLD and two-dimensional principal component analysis combined with k-nearest neighbor (ATLD-kNN and 2DPCA-kNN) and ATLD combined with data-driven soft independent modeling of class analogies (ATLD-DD-SIMCA) were applied to rapid detection of adulteration in saffron. 2DPCA-kNN and ATLD-DD-SIMCA methods were adopted for the classification of chemical EEM data, first with 100% correct classification rate. The content of adulteration of adulterated saffron was predicted by the N-way partial least squares regression (N-PLS) algorithm. In addition, new samples were correctly classified and the adulteration level in adulterated saffron was estimated semi-quantitatively, which verifies the reliability of these models.

CONCLUSION

ATLD-DD-SIMCA and 2DPCA-kNN are recommended methods for the classification of pure saffron and adulterated saffron. The N-PLS algorithm shows potential in prediction of adulteration levels. These methods are expected to solve more complex problems in food authenticity. © 2023 Society of Chemical Industry.

Production of Saffron Apocarotenoids in Nicotiana benthamiana Plants Genome-Edited to Accumulate Zeaxanthin Precursor

Crocins are glycosylated apocarotenoids with strong coloring power and anti-oxidant, anticancer, and neuro-protective properties. We previously dissected the saffron crocin biosynthesis pathway, and demonstrated that the CsCCD2 enzyme, catalyzing the carotenoid cleavage step, shows a strong preference for the xanthophyll zeaxanthin in vitro and in bacterio. In order to investigate substrate specificity in planta and to establish a plant-based bio-factory system for crocin production, we compared wild-type Nicotiana benthamiana plants, accumulating various xanthophylls together with α- and β-carotene, with genome-edited lines, in which all the xanthophylls normally accumulated in leaves were replaced by a single xanthophyll, zeaxanthin. These plants were used as chassis for the production in leaves of saffron apocarotenoids (crocins, picrocrocin) using two transient expression methods to overexpress CsCCD2: agroinfiltration and inoculation with a viral vector derived from tobacco etch virus (TEV). The results indicated the superior performance of the zeaxanthin-accumulating line and of the use of the viral vector to express CsCCD2. The results also suggested a relaxed substrate specificity of CsCCD2 in planta, cleaving additional carotenoid substrates.

Optimized pressurized hot water extraction, HPLC/LC-MS characterization, and bioactivity of Tetrapleura tetraptera L. dry fruit polyphenols

Despite the global preference for green extraction methods in the recovery of plant bioactives, Tetrapleura tetraptera fruit polyphenols (TTP) are yet to receive considerable attention. For the first time, pressurized hot water extraction (PHWE) of TTP was optimized for total phenol content (TPC) and antioxidant activity (AA) using the Box Behnken design of response surface methodology. Predictor variables were time, temperature, and liquid-to-solid ratio. An optimum solution with a desirability of 0.805 was selected and parameters were 43 min, 220°C, and 60 ml g^-1 liquid-to-solid ratio, yielding TPC of 8.92 mg gallic acid equivalent per gram of sample on dry weight basis (GAE g^-1  dw^-1 ) and AA of 70.35%. Purified, optimized TTP were characterized and quantified using HPLC/LC-MS. PHWE mainly extracted rutin (379.04 µg g^-1 ), cyanidin-3-O-glucoside (chloride) (299.55 µg g^-1 ), naringenin 7-O-glucoside (240.11 µg g^-1 ), p-coumaric acid (177.28 µg g^-1 ), isorientin (150.43 µg g^-1 ), and gallic acid (118.06 µg g^-1 ) whereas cyanidin-3-O-glucoside (chloride) (83.27 µg g^-1 ), protocatechuic acid (61.37 µg g^-1 ), rutin (28.03 µg g^-1 ), and gallic acid (22.62 µg g^-1 ) were mainly extracted by hot water extraction, which was a control. PHWE-obtained TTP showed higher cellular antioxidant activity, cytotoxicity in human liver cancer cell lines (HepG2), and antimicrobial property against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis than control. The potential mechanisms underlying the biological activities of some of the major polyphenols extracted were briefly discussed. Considering the wide use of the T. tetraptera (TT) fruit in Africa in foods and medicine, the use of more efficient green extraction methods such as PHWE is recommended. PRACTICAL APPLICATION: This study serves as a baseline for optimizing pressurized hot water extraction, purification, identification, and quantification of Tetrapleura tetraptera polyphenols (TTP) and their biological activities, being the first of its kind. The varied biological effects shown can be exploited further for applications of TTP as nutraceutical agents and preservatives in foods in different forms. Also, the high amounts of gallic acid and other phenolic acids and flavonoids confirmed in this study make TTP good candidates for the development of metal-phenol network nanoparticles to enhance adequate solubility and distribution in food systems in light of the above proposed applications.

Detection of Saffron’s Main Bioactive Compounds and Their Relationship with Commercial Quality

This review aims to evaluate the state of saffron’s main bioactive compounds and their relationship with its commercial quality. Saffron is the commercial name for the dried red stigmas of the Crocus sativus L. flower. It owes its sensory and functional properties mainly to the presence of its carotenoid derivatives, synthesized throughout flowering and also during the whole production process. These compounds include crocin, crocetin, picrocrocin, and safranal, which are bioactive metabolites. Saffron’s commercial value is determined according to the ISO/TS3632 standard that determines their main apocatotenoids. Other techniques such as chromatography (gas and liquid) are used to detect the apocarotenoids. This, together with the determination of spectral fingerprinting or chemo typing are essential for saffron identification. The determination of the specific chemical markers coupled with chemometric methods favors the discrimination of adulterated samples, possible plants, or adulterating compounds and even the concentrations at which these are obtained. Chemical characterization and concentration of various compounds could be affected by saffron’s geographical origin and harvest/postharvest characteristics. The large number of chemical compounds found in the by-products (flower parts) of saffron (catechin, quercetin, delphinidin, etc.) make it an interesting aromatic spice as a colorant, antioxidant, and source of phytochemicals, which can also bring additional economic value to the most expensive aromatic species in the world.

Potential Role of Phytochemical Extract from Saffron in Development of Functional Foods and Protection of Brain-Related Disorders

The present review is designed to measure the effects of saffron extract in functional foods and its pharmacological properties against various disorders. Saffron is a traditional medicinal plant used as a food additive. The stigma of saffron has bioactive compounds such as safranal, crocin, crocetin, picrocrocin, kaempferol, and flavonoid. These bioactive compounds can be extracted using conventional (maceration, solvent extraction, soxhlet extraction, and vapor or hydrodistillation) and novel techniques (emulsion liquid membrane extraction, ultrasound-assisted extraction, enzyme-associated extraction, pulsed electric field extraction, microwave-assisted extraction, and supercritical fluid extraction). Saffron is used as a functional ingredient, natural colorant, shelf-life enhancer, and fortifying agent in developing different food products. The demand for saffron has been increasing in the pharma industry due to its protection against cardiovascular and Alzheimer disease and its antioxidant, anti-inflammatory, antitumor, and antidepressant properties. Conclusively, the phytochemical compounds of saffron improve the nutrition value of products and protect humans against various disorders.

Evaluation of Microwave-Assisted Extraction as a Potential Green Technology for the Isolation of Bioactive Compounds from Saffron (Crocus sativus L.) Floral By-Products

The saffron flower stigmas are used for the saffron spice production while the remaining saffron floral by-products, that are a valuable source of natural bioactive compounds, remain underutilized. The aim of this study was to evaluate the microwave-assisted extraction (MAE) through response surface methodology to obtain high value-added compounds from saffron tepals as ingredients with potential application in the food, pharmaceutical and/or cosmetic industries. A central composite design was applied to optimize process variables: temperature, time and ethanol solvent concentration. Extracts were characterized in terms of total phenolic and total flavonoid content, and antioxidant capacity (ORAC and HOSC assays), being the maximum values obtained: 126.20 ± 2.99 mg GAE/g dry matter; 8.05 ± 0.11 mg CE/g dry matter; 6219 ± 246 μmol TEAC/dry matter; 3131 ± 205 μmol TEAC/dry matter, respectively. Results indicated that the optimal extraction conditions were the combination of low temperature (25 °C)—high extraction time (5 min) using ethanol as solvent (100%). MAE revealed to be an efficient technique to isolate bioactive compounds from saffron floral by-products with a low energy footprint.

Effect of low-pressure cold plasma processing on decontamination and quality attributes of Saffron (Crocus sativus L.)

This study investigated the microbial decontamination of saffron using the low-pressure cold plasma (LPCP) technology. Therefore, other quality characteristics of saffron that create the color, taste, and aroma have also been studied. The highest microbial log reduction was observed at 110 W for 30 min. Total viable count (TVC), coliforms, molds, and yeasts log reduction were equal to 3.52, 4.62, 2.38, and 4.12 log CFU (colony-forming units)/g, respectively. The lowest decimal reduction times (D-values) were observed at 110 W, which were 9.01, 3.29, 4.17, and 8.93 min for TVC, coliforms, molds, and yeasts. LPCP treatment caused a significant increase in the product's color parameters (L*, a*, b*, ΔE, chroma, and hue angle). The results indicated that the LPCP darkened the treated stigma's color. Also, it reduced picrocrocin, safranal, and crocin in treated samples compared to the untreated control sample (p < .05). However, after examining these metabolites and comparing them with saffron-related ISO standards, all treated and control samples were good.

The Relation between Drying Conditions and the Development of Volatile Compounds in Saffron (Crocus sativus)

Saffron is derived from the stigmas of the flower Crocus sativus L. The drying process is the most important post-harvest step for converting C. sativus stigmas into saffron. The aim of this review is to evaluate saffron's post-harvest conditions in the development of volatile compounds and its aroma descriptors. It describes saffron's compound generation by enzymatic pathways and degradation reactions. Saffron quality is described by their metabolite's solubility and the determination of picrocrocin, crocins, and safranal. The drying process induce various modifications in terms of color, flavor and aroma, which take place in the spice. It affects the aromatic species chemical profile. In the food industry, saffron is employed for its sensory attributes, such as coloring, related mainly to crocins (mono-glycosyl esters or di-glycosyl polyene).

Kinetic Study of Subcritical Water Extraction of Scopoletin, Alizarin, and Rutin from Morinda citrifolia

Noni fruits (Morinda citrifolia) are a source of phenolic bioactive compounds (scopoletin, alizarin, and rutin), which have antioxidant, antimicrobial, anticancer, and anti-inflammatory activities. In this study, subcritical water was applied to determine the extraction yields and kinetics of phenolic compounds from noni fruits. The scopoletin and alizarin yields increased with the increase in temperature from 100 to 140 °C, while that of rutin increased up to 120 °C and then decreased at 140 °C. The yields of all the compounds rapidly increased from 1 to 2 mL/min and then slightly up to 3 mL/min of water flow rate. The extraction kinetics were assessed using two mathematical models. The two-site kinetic desorption model had a better fit for all experimental conditions throughout the extraction cycle and best described the extraction kinetics of phenolic compounds from noni fruits. The diffusion coefficients of scopoletin and alizarin at 140 °C and 3 mL/min were 3.7- and 16.2-fold higher than those at 100 °C and 1 mL/min, respectively. The activation energies of alizarin were 2.9- to 8.5-fold higher than those of scopoletin at various flow rates. Thus, subcritical water could be an excellent solvent with higher extraction yields and shorter extraction times using an environmentally friendly solvent.

Surface-decorated graphene oxide sheets with nanoparticles of chitosan-Arabic gum for the separation of bioactive compounds: A case study for adsorption of crocin from saffron extract

This work provides a new perception toward the application of the graphenic-biopolymeric composites as a solid-bed for separation and purification of bioactive compounds. Graphene oxide nanocomposites with functionalized sheets by soluble and insoluble nanocomplexes of chitosan and Arabic gum, were successfully synthesized and employed for the adsorption and purification of crocin, a nutraceutical from saffron. The composites exhibited a nanostructured scaffold with a particle size of 10 nm and experienced an unprecedented increase in the surface area by about 300% and improved d-spacing sheets by 17%. The optimum conditions for crocin separation were temperature = 318 K, stirring rate = 300 rpm, initial concentration = 100 mg L^-1 and pH = 6. Under these conditions, the nanocomposites separated 99.1% of crocin in an equilibrium time of 30 min. The adsorption data were best represented by Freundlich isotherm and pseudo-second-order kinetic models. The thermodynamic studies indicated that the crocin adsorption on nanocomposites was an endothermic, spontaneous and physisorption process. The high-performance liquid chromatography (HPLC) analysis revealed that produced nanocomposites adsorbed crocin efficiently from saffron extract with a purity similar to the standard sample. The possible interaction mechanisms between crocin and nanocomposites were electrostatic interactions and hydrogen bonding.

Subcritical Water Extraction of Natural Products

Subcritical water refers to high-temperature and high-pressure water. A unique and useful characteristic of subcritical water is that its polarity can be dramatically decreased with increasing temperature. Therefore, subcritical water can behave similar to methanol or ethanol. This makes subcritical water a green extraction fluid used for a variety of organic species. This review focuses on the subcritical water extraction (SBWE) of natural products. The extracted materials include medicinal and seasoning herbs, vegetables, fruits, food by-products, algae, shrubs, tea leaves, grains, and seeds. A wide range of natural products such as alkaloids, carbohydrates, essential oil, flavonoids, glycosides, lignans, organic acids, polyphenolics, quinones, steroids, and terpenes have been extracted using subcritical water. Various SBWE systems and their advantages and drawbacks have also been discussed in this review. In addition, we have reviewed co-solvents including ethanol, methanol, salts, and ionic liquids used to assist SBWE. Other extraction techniques such as microwave and sonication combined with SBWE are also covered in this review. It is very clear that temperature has the most significant effect on SBWE efficiency, and thus, it can be optimized. The optimal temperature ranges from 130 to 240 °C for extracting the natural products mentioned above. This review can help readers learn more about the SBWE technology, especially for readers with an interest in the field of green extraction of natural products. The major advantage of SBWE of natural products is that water is nontoxic, and therefore, it is more suitable for the extraction of herbs, vegetables, and fruits. Another advantage is that no liquid waste disposal is required after SBWE. Compared with organic solvents, subcritical water not only has advantages in ecology, economy, and safety, but also its density, ion product, and dielectric constant can be adjusted by temperature. These tunable properties allow subcritical water to carry out class selective extractions such as extracting polar compounds at lower temperatures and less polar ingredients at higher temperatures. SBWE can mimic the traditional herbal decoction for preparing herbal medication and with higher extraction efficiency. Since SBWE employs high-temperature and high-pressure, great caution is needed for safe operation. Another challenge for application of SBWE is potential organic degradation under high temperature conditions. We highly recommend conducting analyte stability checks when carrying out SBWE. For analytes with poor SBWE efficiency, a small number of organic modifiers such as ethanol, surfactants, or ionic liquids may be added.

Selected Aspects Related to Medicinal and Aromatic Plants as Alternative Sources of Bioactive Compounds

Natural compounds obtained from different medicinal and aromatic plants have gained respect as alternative treatments to synthetic drugs, as well as raw materials for different applications (cosmetic, food and feed industries, environment protection, and many others). Based on a literature survey on dedicated databases, the aim of the present work is to be a critical discussion of aspects regarding classical extraction versus modern extraction techniques; possibilities to scale up (advantages and disadvantages of different extraction methods usually applied and the influence of extraction parameters); and different medicinal and aromatic plants' different applications (medical and industrial applications, as well as the potential use in nanotechnology). As nowadays, research studies are directed toward the development of modern, innovative applications of the medicinal and aromatic plants, aspects regarding future perspectives are also discussed.

Extraction optimization by using response surface methodology and purification of yellow pigment from Gardenia jasminoides var. radicans Makikno

Gardenia jasminoides var. radicans Makikno contains rich gardenia yellow pigment (GYP). In this study, the process of pigment extraction was optimized based on a Box-Behnken design (BBD) and response surface methodology (RSM). The absorbance and antioxidant activity (AA) were considered as responses. The result showed that the optimal extraction conditions were ethanol concentration 65.10%, liquid/solid ratio 10:1 ml/g, extraction time 59.85 min, and extraction temperature 60.04℃ for the maximal response values of absorbance (0.79) and AA (91.30%), respectively. Crude GYP was purified by the 13 different resins. The result showed that BJ-7514 was suitable for purifying GYP with the absorption ratio of 95.4%. Moreover, the 80% of ethanol eluent is applicable on the BJ-7514 with the desorption ratio of 91.93%. The major component of GYP (Crocin-3) was isolated and identified from the purified GYP.

Spectroscopic, molecular docking and molecular dynamic simulation studies on the complexes of β-lactoglobulin, safranal and oleuropein

Herbal bioactive compounds have captured pronounced attention considering their health-promoting effects as well as their functional properties. In this study, the binding mechanism between milk protein bovine β-lactoglobulin (β-LG), oleuropein (OLE) and safranal (SAF) found in olive leaf extract and saffron, respectively via spectroscopic and in silico studies. Fluorescence quenching information exhibited that interactions with both ligands were spontaneous and hydrophobic interactions were dominant. Also, the CD spectroscopy results demonstrated the increase in β-sheet structure and decrease in the α-helix content for both ligands. Size of β-LG-OLE complex was higher than β-LG-SAF due to the conformation and larger molecular size. Molecular docking and simulation studies revealed that SAF and OLE bind in the central calyx of β-LG and the surface of β-LG next to hydrophobic residues. Lastly, OLE formed a more stabilized complex compared to SAF based on the molecular dynamic simulation results.

Improving the cancer prevention/treatment role of carotenoids through various nano-delivery systems

One of the emerging and recent strategies to combat cancer is application of natural bioactive compounds and phytochemicals. Carotenoids including lycopene, β-carotene, astaxanthin, crocin, β-cryptoxanthin, and lutein, are the main group of plant pigments which play important roles in the prevention and healing process of different diseases including cancer. The pharmacological use of carotenoid compounds is frequently limited by their low bioavailability and solubility as they are mainly lipophilic compounds. The present study focuses on the current data on formulation of different carotenoid nanodelivery systems for cancer therapy and a brief overview of the obtained results. Encapsulation of carotenoids within different nanocarriers is a remarkable approach and innovative strategy for the improvement of health-promoting features and particularly, cancer prevention/treatment roles of these compounds through enhancing their solubility, cellular uptake, membrane permeation, bioaccessibility, and stability. There is various nanocarrier for loading carotenoids including polymeric/biopolymeric, lipid-based, inorganic, and hybrid nanocarriers. Almost in all relevant studies, these nano delivery systems have shown promising results in improving the efficiency of carotenoids in cancer therapy. [Formula: see text].