Red Cabbage Extract Research Articles

Cruciferous Plant Extracts, Their Isothyocianate or Indol Derivatives, and Their Effect on Cellular Viability of Breast Cancer Cell Lines.

Brassicaceaes are rich in glucosinolates (GSL), whose derivatives, the isothyocianates sulforaphane (SFN), iberine (IB), or indole derivatives as indole-3-carbinol (I3C), have anticancer activities. We evaluated the effects of a broccoli sprout (Brassica oleracea var italica) and red cabbage (B. oleracea L. var capitata f. rubra) extracts and their GSL derivatives on breast cancer cells. Broccoli sprout aqueous extract (BSE) and red cabbage aqueous (RCA) or ethanolic (RCE) extracts were high in SFN, IB, and/or I3C. BSE and RCA decreased proliferation at doses of 2.5-5 mg/mL but induced proliferation at lower doses. RCE decreased proliferation starting at 10 µg/mL with selectivity toward cancer cells. SFN, IB, or I3C alone or in combination did not decrease proliferation similarly, suggesting synergistic effects with other phytochemicals in the extract. RCE showed selectivity toward breast cancer cells, but the effect of the individual metabolites or their combination did not reduce proliferation to the same extent. It will be important to determine the combination responsible for this effect to characterize their use for breast cancer treatment.

EXPLOITING ECO-FRIENDLY NATURAL DYES FROM PLANT SOURCES: EXTRACTION AND DIVERSE APPLICATIONS

Natural pigments extracted from plant sources offer eco-friendly and sustainable alternatives to synthetic colorants. In this study, pigment samples were obtained through aqueous extraction from beetroot (S1), red cabbage (S2), and turmeric (S3). Their physicochemical properties and potential applications were thoroughly evaluated. The research problem addressed in this study is the need to overcome the limitations of natural dyes, such a slower color fastness, reduced reproducibility, and limited color range, in order to promote their wider adoption in various industries as sustainable alternatives to synthetic colorants. The pigment extracts were assessed for their suitability in textile dyeing, paper pH indicators, food coloring, ink production, and natural stamp pad formulations. Cotton and wool fabrics were dyed by adding traditional mordants, and the pigment-treated textiles exhibited distinctive color changes and varying levels of color fastness. The pigment samples demonstrated the ability to act as effective acid-base indicators, displaying characteristic color transitions in response to varying pH levels. When used as natural food colorants, the extracts imparted attractive hues to rice and cream without altering their flavor profiles. The feasibility of incorporating these plant-derived pigments in ink manufacturing and stamp pad production was also explored. Beetroot pigment exhibited superior color retention and fastness properties, while red cabbage and turmeric extracts displayed effectiveness in selected applications. The findings of this comprehensive study highlight the viability of these plant sources as natural substitutes for synthetic colorants in diverse fields. The observed performance characteristics and the eco-friendly nature of the pigments underscore their potential to serve as sustainable alternatives in various industries.

Solubility, Mechanical and Thermal Properties of Cassava Starch-Chitosan Film Incorporated with Red Cabbage Extract

Solubility, Mechanical and Thermal Properties of Cassava Starch-Chitosan Film Incorporated with Red Cabbage Extract

Red cabbage extract immobilized in bacterial cellulose film as an eco-friendly sensor to monitor microbial contamination and gamma irradiation of stored cucumbers

The aim of the present study is to develop a pH-sensing biopolymer film based on the immobilization of red cabbage extract (RCE) within bacterial cellulose (BC) to detect contamination and gamma radiation exposure in cucumbers. The results obtained show a sensitivity to pH changes for RCE in its aqueous form and that incorporated within BC films (RCE-BC), both showed color change correlated to bacterial growth (R2 = 0.91), this was supported with increase in pH values from 2 to 12 (R2 = 0.98). RCE and RCE-BC exposure to gamma radiation (0, 2.5, 5, 10, 15, 20, 25 kGy) resulted in gradual decrease in color that was more evident in RCE aqueous samples. To sense bacterial contamination of cucumbers, the total count was followed at 0, 5, 10 and 15 days in cold storage conditions and was found to reach 9.13 and 5.47 log cfu/mL for non-irradiated and 2 kGy irradiated samples, respectively. The main isolates detected throughout this storage period were identified as Pseudomonas fluorescens, Erwinia sp. Pantoea agglomerans using matrix assisted laser desorption ionization–time of flight-ms (MALDI–TOF–MS). Bacterial growth in stored irradiated cucumbers was detected by color change within 5 and 10 days of storage, after which there was no evident change. This is very useful since contamination within the early days of storage cannot be sensed with the naked eye. This study is the first to highlight utilizing RCE and RCE-BC as eco-friendly pH-sensing indicator films for intelligent food packaging to detect both food contamination and gamma preservation for refrigerator stored cucumbers.

Green synthesis of nano zero-valent iron doped on bimetallic Ti/Mo-MOF for highly sensitive Peroxidase like colorimetric detection of Cholesterol and antioxidant/antimicrobial efficiencies

In this research paper, we report a clean and simple approach for the phytosynthesis of nanoparticles zero-valent iron (nZVI) through the in situ reduction of Fe2+ to Fe0 using red cabbage extract. These nZVI were then loaded onto a Ti/Mo-MOF nanostructure, resulting in the formation of a novel nZVI@Ti/Mo-MOF nanocomposite. To synthesize the nanoparticles zero-valent iron, we utilized red cabbage extract as a reducing agent. Subsequently, the synthesized nanoparticles zero-valent iron were incorporated into a Ti/Mo-MOF to create the nZVI@Ti/Mo-MOF nanocomposite. The characterization of the biosynthesized nZVI@Ti/Mo-MOF nanocomposite was conducted using UV–vis spectroscopy, FT-IR, XRD, XPS, FESEM, and EDS. The nZVI@Ti/Mo-MOF nanocomposite was used to sensitive peroxidase colorimetric sensing of cholesterol. Under optimal conditions, the cholesterol concentration range was investigated from 1.0 nM to 100.0 nM, which that show a linear relationship with detection response. The detection limit of the nZVI@Ti/Mo-MOF sensor is 6.24 nM. Furthermore, we investigated the antioxidant properties and antimicrobial activity of the nZVI@Ti/Mo-MOF nanocomposite and its constituents against four bacterial strains as well as two fungal strains. Additionally, the nanocomposite demonstrated superior antioxidant properties compared to other synthesized compounds and paves a way for manufacturing innovation.

Characterization of Red Cabbage Extracts incorporated in Green Based Gelatin Active Films

This study aimed to assess red cabbage extracts obtained using solvents with different pH levels and alcohol concentrations, comparing their phytochemical quantities and functional characteristics. Solvents—purified water (PW, pH 7), 70% and 99% ethanol (70%E and 99%E, pH 6.5), and acidified ethanol (AE, pH 2)—were employed for extraction. When the different pH solutions were applied to the red cabbage extracts, they altered the extract's color, ranging from pink to yellow, influenced by various anthocyanin forms responsive to pH levels. The AE-extracted red cabbage displayed the highest UV and visible light barrier and total phenolic content (TPC). Then, the AE extract was used to formulate the green-based gelatin active films, alongside the 99%E extract, which had similar alcohol content and TPC values. The films averaged 20-21 μm in thickness. Moreover, incorporating both extracts into the gelatin films increased moisture content and water solubility, though the change in water vapor permeability was not significant compared to the neat gelatin film. The gelatin film incorporating AE-extracted red cabbage (GAE) showed higher water solubility than that incorporating the 99%E extract (GE). Both green-based gelatin active films showed differences in appearance color in the third week. The GAE film exhibited greater color stability, attributed to anthocyanin's distinctive chemical structures favoring acidic environments. This gelatin film incorporating red cabbage by AE-extracted holds promise as an eco-friendly active food packaging material.

Antioxidant and antimicrobial potentials of biosynthesized Ag-Doped Ni-MOF as a novel hybrid nanocomposite

Metal-organic frameworks (MOFs) are organic–inorganic crystalline compounds that have attracted much attention due to their wide range of applications. Bimetallic MOFs offer more possibilities than MOFs based on single metal. This study focuses on the synthesis and characterization of a Ni-MOF doped with silver nanoparticles (Ag NPs) as potent antioxidant and antimicrobial agent. Red cabbage extract was used as a reducing agent to synthesize Ag NPs. Ag@Ni-MOF nanocomposite exhibited significant growth inhibition of bacteria and fungi, and demonstrated the best antioxidant properties among the synthesized compounds. These results suggest that designed Ag@Ni-MOF nanostructure can be applied in the treatment of oxidative stress-related diseases as well as bacterial/fungal infections.

Application of On-Pack pH Indicators to Monitor Freshness of Modified Atmospheric Packaged Raw Beef

Abstract Three on-pack visual indicators for the real-time monitoring of raw beef steaks in a modified atmospheric packaging (MAP) environment were developed. The indicators were prepared by spray deposition of a nanocellulose (NC) suspension (1.5 wt. %) with the desired concentration of the pH-sensitive indicators, either red cabbage (RC) extract, black carrot (BC) extract, or chlorophenol red (CPR). The responsiveness of the colorimetric pH indicators, assessed visually and by CIE-Lab quantitative analysis, to the freshness of raw beef steaks stored under MAP conditions at 4 °C or 20 °C, was analysed over 7 days. All indicators gave a colour change for beef steak stored at 4 °C for 7 days that was noticeable with the naked eye and had a ΔE value >12. The sensitivity of the RC pH indicator was superior to the BC and CPR pH indicators. A study linking total microbial count (aerobic + Escherichia coli + coliform) and the quantitative colorimetric response of the indicators (ΔE) revealed a strong linear correlation. Thus, it was concluded that the developed colorimetric pH indicators could be used to monitor the freshness of raw beef and as an alternative to the best-before date commonly used in pre-packaged meat.

Exploring deep eutectic solvent extraction's impact on anthocyanin degradation kinetics in various conditions

This study evaluated the stability of anthocyanins in red cabbage extracts using deep eutectic solvents (DESs) and acidified methanol under thermal and storage conditions. DESs included combinations of choline chloride with malic acid (Ma), xylitol (Xy), lactic acid (La), and glycerol (Gl). Extracts were heat-treated at 40 °C–100 °C and stored at temperatures of 25 °C, 4 °C, and −18 °C for 35 days. Analysis involved pH differential methodology, browning and polymeric color indexes, antioxidant assays (DPPH• and ABTS•+), HPLC, and FT-IR spectroscopy. Results showed that anthocyanin content in all solvents decreased with increasing temperature. Acidified methanol samples experienced a notable reduction from 304.2 mg/L at 40 °C to 246.5 mg/L at 100 °C. Malic acid, lactic acid, xylitol, and glycerol samples also showed significant declines at higher temperatures. Cold storage effectively preserved anthocyanin levels. Kinetic analysis indicated that ChCl-Xy was the most effective solvent in preserving anthocyanins and minimizing browning, while ChCl-Ma led to the highest anthocyanin degradation and color changes. At 25 °C, Ac-MetOH demonstrated the highest antioxidant activity (DPPH• scavenging rate k of 5.66 ± 0.15), but ChCl-Ma exhibited the highest browning index (k of 3.4 ± 0.13) and polymeric color index (k of 5.54 ± 0.12), suggesting lower stability compared to other solvents.

The effect of pH and extraction time on total phenolic content and antioxidant properties of coloured water extracts from Brassica Oleracea

Red cabbage (Brassica oleracea) is a rich source of phenolic content including colour pigments and have also high antioxidant capacities. The amounts of their phenolic substances and antioxidant activities change depending on the extraction conditions (pH, time, solvent, etc.). In this work, the coloured water extract was obtained from red cabbage at different pH values (pH 4-10) for both an hour and 24 hours. The extracts were evaluated regarding total phenolic contents and antioxidant activities. The results showed that the total phenolic content of red cabbage extracts in all extraction conditions ranged from 4.93±0.20 to 7.59±1.22 mg GAE/g fw. The highest total phenolic contents (7.59±1.22 mg GAE/g fw) were obtained from red cabbage at 24 h and pH=6. On the other hand, the red cabbage extracts have high DPPH (IC50 values ranged from 0.21±0.06 to 0.94±0.03 mg/mL) and ABTS (IC50 values ranged from 0.29±0.01 to 0.46±0.05 mg/mL) activities at all pH values and times. The extract obtained from red cabbage at 1 h and pH=7 exhibited the strongest DPPH activity with the IC50 values of 0.21±0.06 mg/mL, it showed the best ABTS activity with the IC50 values of 0.29±0.01 mg/mL at 1 h and pH=5 and 8.

Health-Promoting Properties of Processed Red Cabbage (Brassica oleracea var. capitata f. rubra): Effects of Drying Methods on Bio-Compound Retention.

The aim of this work is to describe the effect of convective drying (CD), vacuum drying (VD), infrared drying (IRD), low-temperature vacuum drying (LTVD) and freeze drying (FD) on bio-compound retention of red cabbage and its beneficial health properties. The total phenolics content (TPC), flavonoids (TFC), anthocyanin (TAC) and glucosinolates (TGC) were determined by spectrophotometry. The profiles of phenolic acids, amino acids and fatty acids were determined by HPLC-UV-DAD, LC-DAD and GC-FID, respectively. Antioxidant potential was verified by DPPH and ORAC assays. The antiproliferative activity was measured in the human gastric cell line (AGS). Anti-inflammatory activity was evaluated by phorbol 12-myristate 13-acetate and arachidonic acid models. VD showed high values of TPC = 11.89 ± 0.28 mg GAE/g d.m.; TFC = 11.30 ± 0.9 mg QE/g d.m.; TAC = 0.265 ± 0.01 mg Cya3glu/g d.m.; and TGC = 51.15 ± 3.31 µmol SE/g d.m. Caffeic acid, ferulic acid and sinapic acid were identified. The predominant amino acid and fatty acid were glutamic acid and γ-linolenic acid, respectively. The antioxidant potential was dependent on drying methods for both DPPH and ORAC assays. Dried red cabbage extracts showed clear anti-inflammatory and antiproliferative activity. The dehydration process is an alternative for the retention of bio-compounds and health-promoting properties of red cabbage.

Spectrophotometry and Histological Staining Potential of Ethanol Extract of brassica Oleracea (Red Cabbage) on Selected Organs of Sprague Dawley rat

Objective: Plants with coloring and dyeing effects have widely been used in histological staining. Natural dyes are less expensive, nontoxic, renewable and sustainable resources, with minimal environmental impact compared to synthetic stains. Red cabbage is one of such natural dyes. The red color of the red cabbage derived from anthocyanin pigments confers a great advantage to red cabbage. In this study, the physiochemical and spectrophotometric characteristics of red cabbage as well as its histological staining potentials on various tissues were carried out to determine its tissue specificity. Methods:The ethanol extract of red cabbage was prepared using 100% ethanol, then pH, spectrophotometry, and concentration of the red cabbage ethanol extract were measured before the solution was divided into two equal volumes, and one part was added with 2ml glacial acetic acid while the other part was added with 10g of aluminum sulfate. The two solutions were used to stain 10% neutral-buffered formalin-fixed, paraffin-wax-embedded tissue sections separately. Stained sections were viewed with a photomicroscope. Results: The ethanol extract was acidic at a pH of 4.89 and the spectrophotometry graph showed 3 peak absorbances at the wavelengths of 395nm, 545nm and 670nm. The maximum absorbance was 0.795 at the wavelength of 395nm and this is indicative of the pigment cyanidin which is the anthocyanin present in red cabbage. The red cabbage ethanol extract with both glacial acetic acid and aluminum sulfate showed good histological details in tissues of kidney, stomach, lungs, liver, spleen, small intestine and skin. There was no difference between the red cabbage ethanol extract and the conventional hematoxylin and eosin stain (P>0.05). Our study showed that red cabbage ethanol extract with acetic acid and aluminum sulfate is stable at 4oC, with color amber to light gold with a pH of 4.89 and a concentration of 1000 which gave good histological details. In general, our result indicates that red cabbage ethanol extract is an efficient stain for histological tissue structures and can be used as an eco-friendly alternative to eosin. Conclusion: Red cabbage ethanol extract stained basic structures of the cell such as the cytoplasm, muscle fibers and mucins. Therefore, red cabbage ethanol extract can be used in histological staining when appropriate modifications are done.

Enhanced Preservation of Climacteric Fruit with a Cellulose Nanofiber-Based Film Coating.

Bananas are a typical climacteric fruit with high respiration and ethylene production rates after harvest, and they show rapid ripening-senescence phenotypes. Here, we demonstrate that carboxymethylcellulose nanofibers (CM-CNFs) and red cabbage extracts (RCE) can be used as a unique film coating formulation for enhancement of the shelf-life of fruit. A CM-CNF suspension solution is created through a process involving chemical modification, followed by mechanical grinding. It has a high aspect ratio that allows for the creation of a thin and transparent film on the surface of bananas. The cross-linked CM-CNF hydrogel forms a dense film layer on the banana surface during dehydration and prevents respiration and weight loss. RCE contains polyphenols acting as antioxidants, which prevent the appearance of black dots on the banana peels. It serves to mitigate the browning of banana skins and also hinders the respiration process, consequently slowing the aging of bananas.

Sustainable Recovery of Anthocyanins and Other Polyphenols from Red Cabbage Byproducts.

The objective of this work was to develop a sustainable process for the extraction of anthocyanins from red cabbage byproducts using, for the first time, apple vinegar in extractant composition. Our results showed that the mixture 50% (v/v) ethanol-water, acidified with apple vinegar, used in the proportion of 25 g of red cabbage by-products per 100 mL of solvent, was the best solvent for the preparation of an anthocyanin extract with good stability for food applications. The chemical characterization of this extract was performed by FTIR, UV-VIS, HPLC-DAD, and ICP-OES. The stability was evaluated by determining the dynamics of the total polyphenol content (TPC) and the total monomeric anthocyanin pigment content (TAC) during storage. On the basis of the statistical method for analysis of variance (ANOVA), the standard deviation between subsamples and the repeatability standard deviation were determined. The detection limit of the stability test of TPC was 3.68 mg GAE/100 g DW and that of TAC was 0.79 mg Cyd-3-Glu/100 g DW. The red cabbage extract has high TPC and TAC, good stability, and significant application potential. The extracted residues, depleted of anthocyanins and polyphenols with potential allelopathic risks, fulfill the requirements for a fertilizing product and could be used for soil treatment.

Nanoencapsulation of Anthocyanins from Red Cabbage (Brassica oleracea L. var. Capitata f. rubra) through Coacervation of Whey Protein Isolate and Apple High Methoxyl Pectin.

Encapsulation is a valuable strategy to protect and deliver anthocyanins (ACNs), phenolic compounds with outstanding antioxidant capacity but limited stability. In this study, coacervation was used to encapsulate an ACN-rich red cabbage extract (RCE). Two agri-food by-product polymers, whey protein isolate (WPI) and apple high-methoxyl pectin (HMP), were blended at pH 4.0 in a specific ratio to induce the formation of nanoparticles (NPs). The process optimisation yielded a monodispersed population (PDI < 0.200) of negatively charged (-17 mV) NPs with an average diameter of 380 nm. RCE concentration influenced size, charge, and antioxidant capacity in a dose-dependent manner. NPs were also sensitive to pH increases from 4 to 7, showing a progressive breakdown. The encapsulation efficiency was 30%, with the retention of ACNs within the polymeric matrix being influenced by their chemical structure: diacylated and/or C3-triglucoside forms were more efficiently encapsulated than monoacylated C3-diglucosides. In conclusion, we report a promising, simple, and sustainable method to produce monodispersed NPs for ACN encapsulation and delivery. Evidence of differential binding of ACNs to NPs, dependent on specific acylation/glycosylation patterns, indicates that care must be taken in the choice of the appropriate NP formulation for the encapsulation of phenolic compounds.

A Study on the Phenolic Acid Compositions, Antioxidant Activities and Cell Cytotoxicity of Red Cabbage Leaf Extract as Functional Cosmetic Raw Materials

The total polyphenol and flavonoid content, phenolic acid composition and contents, some antioxidant activity effects, and cytotoxicity against HaCaT cell line of red cabbage leaf hot water extract were investigated as follows. As a result of measuring the total polyphenol and flavonoid content, the total flavonoid content was slightly higher than the total polypheol content. As a result of analyzing the composition and contents of phenolic acid and flavonoid, two types of phenolic acid were identified, but flavonoid was not identified. DPPH and ABTS radical scavenging activity, and FRAP tended to increase as the treatment concentration increased, and this tendency was found to have statistical significance (p&lt;.001). The degree of cytotoxicity to the HaCaT cell line was found to increase with increasing treatment concentration, and at a treatment concentration of 100 μg/ml, cell growth was reduced by about 22% compared to the control. Therefore, the hot-water extract of red cabbage leaves has significant antioxidant activity, and it is considered that it may be used as a natural antioxidant for functional cosmetic raw materials. However, it is considered that there is a need for more continuous research on the degree of cytotoxicity according to the cell line.

Digital image-based quantification of ethanol in distilled spirits using red cabbage (Brassica oleracea) extract

Digital image-based quantification of ethanol in distilled spirits using red cabbage (Brassica oleracea) extract

On-site colorimetric food spoilage monitoring with smartphone embedded machine learning

Real-time and on-site food spoilage monitoring is still a challenging issue to prevent food poisoning. At the onset of food spoilage, microbial and enzymatic activities lead to the formation of volatile amines. Monitoring of these amines with conventional methods requires sophisticated, costly, labor-intensive, and time consuming analysis. Here, anthocyanins rich red cabbage extract (ARCE) based colorimetric sensing system was developed with the incorporation of embedded machine learning in a smartphone application for real-time food spoilage monitoring. FG-UV-CD100 films were first fabricated by crosslinking ARCE-doped fish gelatin (FG) with carbon dots (CDs) under UV light. The color change of FG-UV-CD100 films with varying ammonia vapor concentrations was captured in different light sources with smartphones of various brands, and a comprehensive dataset was created to train machine learning (ML) classifiers to be robust and adaptable to ambient conditions, resulting in 98.8% classification accuracy. Meanwhile, the ML classifier was embedded into our Android application, SmartFood++, enabling analysis in about 0.1 s without internet access, unlike its counterpart using cloud operation via internet. The proposed system was also tested on a real fish sample with 99.6% accuracy, demonstrating that it has a great advantage as a potent tool for on-site real-time monitoring of food spoilage by non-specialized personnel.

Characterisation of acylated anthocyanins from red cabbage, purple sweet potato, and Tradescantia pallida leaves as natural food colourants by HPLC-DAD-ESI(+)-QTOF-MS/MS and ESI(+)-MSn analysis.

Anthocyanins in red cabbage, sweet potato, and Tradescantia pallida leaves were characterised. A total of 18 non-, mono-, and diacylated cyanidins was identified in red cabbage by high performance liquid chromatography-diode array detection coupled to high-resolution and multi-stage mass spectrometry. Sweet potato leaves contained 16 different cyanidin- and peonidin glycosides being predominantly mono- and diacylated. In T. pallida leaves, the tetra-acylated anthocyanin tradescantin prevailed. The large proportion of acylated anthocyanins resulted in a superior thermal stability during heating of aqueous model solutions (pH 3.0) coloured with red cabbage and purple sweet potato extracts as compared to that of a commercial Hibiscus-based food dye. However, their stability was still outperformed by that of the most stable Tradescantia extract. Comparing vis spectra from pH 1-10, the latter had an additional, uncommon absorption maximum at approx. 585nm at slightly acidic to neutral pH values, yielding intensely red to purple colours.

In Vitro Bioactivities of Commonly Consumed Cereal, Vegetable, and Legume Seeds as Related to Their Bioactive Components: An Untargeted Metabolomics Approach Using UHPLC-QTOF-MS2.

We conducted a comprehensive evaluation of the antioxidant, anti-obesity, anti-diabetic, and anti-glycation activities associated with the consumption of broccoli, red cabbage, alfalfa, and buckwheat seeds. Additionally, we explored the relationship between these biological activities and the profiles of amino acids, polyphenols, and organic acids identified in the seeds. Our findings demonstrated that red cabbage, broccoli, and buckwheat extracts exhibited significantly higher antioxidant potential compared to the alfalfa extract. Moreover, buckwheat displayed the most significant capacity for inhibiting alpha-glucosidase. Remarkably, broccoli and red cabbage demonstrated substantial anti-glycation and lipase inhibitory potentials. We identified the presence of amino acids, polyphenols, and organic acids in the extracts through untargeted metabolomics analysis. Correlation analysis revealed that pyroglutamic acid positively correlated with all the investigated functional properties. Most polyphenols made positive contributions to the functional properties, with the exception of ferulic acid, which displayed a negative correlation with all tested biological activities. Furthermore, gluconic acid and arabinonic acid among the organic acids identified displayed a positive correlation with all the functional properties. These results strongly support the anti-diabetic, anti-obesity, and anti-glycation potential of red cabbage, broccoli, and buckwheat seeds.