Natural Red Colorant Research Articles

Brazilin Content, Color Stability, and Antioxidant Activity of Sappan Wood (Caesalpinia Sappan L.) Traditional Drink by Different Blanching and Drying Methods

Caesalpinia sappan L (CS) heartwood is used as a natural red colorant in several Asian ethnic traditional drinks both as sole ingredient or mixed with other herbs. However, the pigment is unstable and easily degraded during storage which affects consumer acceptance. This research aimed to investigate the effect of different blanching and drying methods on the color stability, brazilin content, and antioxidant activity of CS heartwood drinks. Steam blanching, water blanching, sun drying and cabinet drying were examined in this study. The most common method applied in traditional production, without blanching and sun drying, was used as a control. The experimental design used was complete randomized design with triplicates. Data are presented as mean ± standard deviation and analyzed by SPSS statistics version 20. The results showed that blanching and drying methods affected the color intensity. For a pure CS heartwood herbal drink, the sample prepared with water blanching and cabinet drying (BCD) showed the highest red value, leading to a 48 % improvement compared to the control. This red value is in accordance with the brazilin content. Sample BCD showed the highest brazilin content, which was 376 % higher than that of the control. Similarly, the BCD sample had the highest antioxidant activity and total phenolic content, with IC50 values of 98.99 ppm and 213.12 mg GAE g–1, respectively. This result revealed that brazilin might act as an antioxidant. Similar to the pure CS drink, the highest quality of mixed herbal drink was obtained by BCD sample. The results suggest that the combination of water blanching and cabinet drying (BCD) was the best method to improves the quality of CS heartwood drink both in pure and mixed herbal drinks as a functional drink. HIGHLIGHTS Samples treated with blanching and drying had higher brazilin content of Sappan heartwood drink There is a correlation between brazilin content and color intensity as well as antioxidant activity Blanching and cabinet drying improved the color stability of Sappan heartwood drink Blanching and cabinet drying increased the total phenolic and flavonoid content of Sappan heartwood drink GRAPHICAL ABSTRACT

Development of a scalable, high-anthocyanin and low-acidity natural red food colorant from Hibiscus sabdariffa L.

The hibiscus calyx contains 0.3–2.4% total anthocyanins, and is a promising source for naturally red food colorants. In this study, commercially available hibiscus calyces were subjected to ethanolic-aqueous extraction and chromatographic enrichment with the XAD-7HP resin, to create scalable, high-anthocyanin and low-acidity natural food colorants. Anthocyanins, organic and phenolic acids were monitored after each step using UHPLC-DAD and UHPLC-QQQ/MS. 75.67% total anthocyanins were recovered from calyces after double extractions, and the content increased by 8.50–14.90 times after the column enrichment, reaching 14.51–31.90% (by dry weight) in the final product. Chromatographic fractionation was also shown to effectively increase the total phenolic acids by 11.01–16.22 times, and remove an average of 98.58% of the total organic acids. High intensity redness at pH 2.5–3.5 indicated that the final product may be a promising, versatile natural food and beverage colorant in low pH products.

Effect of gamma irradiation and electrospinning applications on the physicochemical, antioxidant, and molecular properties of anthocyanin colorant obtained from black carrot pomace

This research article describes the approach of the electrospinning technique for the development of nanofibers from anthocyanin powder and the possibility of using biodegradable polymers, such as gelatin. The irradiation technique was also examined to improve the technological properties of the AP, which was prepared from black carrot pomace. In the present study, the monomeric anthocyanin content of the anthocyanin powder was reduced from 254.6 to 167.9 mg/g after irradiation treatment. The nano-encapsulated anthocyanin powder with wall material showed stronger color properties compared to those of the irradiated samples. FTIR results revealed that changes in OH stretching and galacturonic acid peaks were observed in anthocyanin powder samples at wave numbers of 3500–3200 cm−1 and 800–1000 cm−1, respectively. The electrospinning technique showed a significant improvement in the thermal stability of the AP compared to that with irradiation. Based on this evidence thus far, it can be concluded that irradiation and electrospinning are promising techniques to develop a natural red colorant from industrial food waste for food, food supplement, and pharmaceutical applications. Industrial relevanceNatural colorants are attracting growing attention as a result of consumer demand. For this reason, the black carrot pomace can be considered an important source of natural colorants from industrial food waste resulting from juice extraction. However, the use of BCP to produce red colorants for various products (eg., food and food supplements) is not an easy task. In this regard, both electrospinning and irradiation are beneficial and effective technologies to produce a red colorant from industrial food waste sources, and improve its technological properties that provide opportunities for clean labeling.

Debottlenecking the L-DOPA 4,5-dioxygenase step with enhanced tyrosine supply boosts betalain production in Nicotiana benthamiana.

Synthetic biology provides emerging tools to produce valuable compounds in plant hosts as sustainable chemical production platforms. However, little is known about how supply and utilization of precursors is coordinated at the interface of plant primary and specialized metabolism, limiting our ability to efficiently produce high levels of target specialized metabolites in plants. L-Tyrosine is an aromatic amino acid precursor of diverse plant natural products including betalain pigments, which are used as the major natural food red colorants and more recently a visual marker for plant transformation. Here, we studied the impact of enhanced L-tyrosine supply on the production of betalain pigments by expressing arogenate dehydrogenase (TyrA) from table beet (Beta vulgaris, BvTyrAα), which has relaxed feedback inhibition by L-tyrosine. Unexpectedly, betalain levels were reduced when BvTyrAα was coexpressed with the betalain pathway genes in Nicotiana benthamiana leaves; L-tyrosine and 3,4-dihydroxy-L-phenylalanine (L-DOPA) levels were drastically elevated but not efficiently converted to betalains. An additional expression of L-DOPA 4,5-dioxygenase (DODA), but not CYP76AD1 or cyclo-DOPA 5-O-glucosyltransferase, together with BvTyrAα and the betalain pathway, drastically enhanced betalain production, indicating that DODA is a major rate-limiting step of betalain biosynthesis in this system. Learning from this initial test and further debottlenecking the DODA step maximized betalain yield to an equivalent or higher level than that in table beet. Our data suggest that balancing between enhanced supply ("push") and effective utilization ("pull") of precursor by alleviating a bottleneck step is critical in successful plant synthetic biology to produce high levels of target compounds.

Beetroot Stalk Extract as a Functional Colorant for Stirred Yogurt Beverages: Effect on Nutritional Value and Stability during Storage

Betalains are natural red colorants characterized by their stability to anthocyanins, particularly in acidic foods. Beetroot stalks are a good source of betalains, with higher bioactive components than the whole root. Hence, the current study aims to investigate the potential use of beetroot stalk water extract (BSE) as a functional colorant for raspberry-flavored stirred yogurt. For this purpose, the betalains of BSE and their stability at pH 4 and 5 were investigated in addition to the phenolic and flavonoid content. Furthermore, the antioxidant and antimicrobial activities of BSE were characterized. Subsequently, BSE was added to raspberry-flavored stirred yogurt at concentrations of 1 (T1), 2 (T2), and 5% (T3) to study the stability of betalains, the physicochemical properties, the nutritional value, and the viability of lactic acid bacteria during storage (14 days/4 °C). BSE showed a considerable amount of betalains (456.82 mg/L) and phenolics (139.87 mg/g), with a high content of chlorogenic and ferulic acids. The betalains showed greater stability at pH 4 than pH 5 after 14 days of cold storage (275.05 and 247.00 mg/L, respectively). Applying BSE resulted in a functional beverage with high phenolic content (116.55 ± 1.23 mg/g) and flavonoids (71.77 ± 0.57 mg/g) in T3 (5%) compared to the control (95.11 ± 1.12 and 64.72 ± 0.29 mg/g, respectively). The beverages shared high DPPH scavenging activity (IC50 = 71.68 ± 1.30– 69.18 ± 0.48) compared with the control (78.47 ± 3.27 µL/mL). BSE significantly increased the betalain level in yogurt from 44.19 ± 0.05 mg/L to 67.86 ± 0.54 mg/L, resulting in pale red beverages with a redness value of 6.38–9.68 on day 1. By day 14, the redness of the treatments decreased by 6–18% compared with the first day, reaching 5.25 ± 0.03 (T1), 7.87 ± 0.03 (T2), and 8.43 ± 0.05 (T3) due to the degradation of betalains. Generally, BSE is a promising natural colorant when added to stirred yogurt, and it has preferable physical and sensory properties, as it improves the stability of the red color throughout cold storage and increases the nutritional quality. The use of beet stalks as a natural and functional colorant is presented for the first time in the current investigation.

Influence of processing temperature on production of red beetroot powder as a natural red colorant using foam-mat drying: Experimental and modeling study.

With high medicinal and nutritional value, red beetroot powder is utilized as a natural pigment and functional additive in various food industries. In this investigation, red beetroot powder was produced using foam-mat drying, and the effect of drying temperature on quality attributes was evaluated. Computer simulation was also performed to assess the impact of temperature on uniformity of moisture loss and temperature during drying. Temperature variations did not exert a significant impact on water solubility and total color difference of the powders. Images obtained from field emission scanning electron microscopy illustrated that with increasing temperature, wrinkling, cracking, and roughness of the powder particles reduced because of the formation of smooth and hard crusts on the particles' surface. Predicted moisture content values were in good agreement with measured data. The results of this study could be used to optimize foam-mat drying of red beetroot to produce functional powders with suitable physicochemical and microstructural characteristics.

Combinatorial engineering of betalain biosynthesis pathway in yeast Saccharomyces cerevisiae

BackgroundBetalains, comprising red–violet betacyanins and yellow–orange betaxanthins, are the hydrophilic vacuolar pigments that provide bright coloration to roots, fruits, and flowers of plants of the Caryophyllales order. Betanin extracted from red beets is permitted quantum satis as a natural red food colorant (E162). Due to antioxidant activity, betanin has potential health benefits.ResultsWe applied combinatorial engineering to find the optimal combination of a dozen tyrosine hydroxylase (TyH) and 4,5-dopa-estradiol-dioxygenase (DOD) variants. The best-engineered Saccharomyces cerevisiae strains produced over six-fold higher betaxanthins than previously reported. By genome-resequencing of these strains, we found out that two copies of DOD enzyme from Bougainvillea glabra together with TyH enzymes from Abronia nealleyi, Acleisanthes obtusa, and Cleretum bellidiforme were present in the three high-betaxanthin-producing isolates. Next, we expressed four variants of glucosyltransferases from Beta vulgaris for betanin biosynthesis. The highest titer of betanin (30.8 ± 0.14 mg/L after 48 h from 20 g/L glucose) was obtained when completing the biosynthesis pathway with UGT73A36 glucosyltransferase from Beta vulgaris. Finally, we investigated betalain transport in CEN.PK and S288C strains of Saccharomyces cerevisiae and identified a possible role of transporter genes QDR2 and APL1 in betanin transport.ConclusionsThis study shows the potential of combinatorial engineering of yeast cell factories for the biotechnological production of betanin.

Parametric Study and Characterization of Sappan Wood (Caesalpinia Sappan Linn) Natural Red Colorant Extract with Ultrasonic Assisted Extraction Method

In this study, the optimization and characterization of the colorant extraction process from sappan wood were carried out using the ultrasound-assisted extraction method. Sappan is proposed as a source of natural material wealth, producing a natural red colorant that is being needed by the community in the food sector. Based on this research, the optimum operating conditions for the extraction of sappan wood were obtained using a frequency of 40 kHz, a temperature of 60 °C, a ratio of 0.0050 g mL-1, an extraction time of 20 min, and the use of 60% ethanol solvent. Sappan wood extract created a yellow to reddish orange color at acidic pH (2-6), red at neutral pH (7) and shifted towards purplish red with increasing pH. The extract was qualitatively positive containing quinone, flavonoid, quinone, and tannin compounds, as well as several phenolic compounds detected in the Gas Chromatography Mass Spectroscopy qualitative test.

Natural fluorescent red colorants produced by Talaromyces amestolkiae as promising coloring agents for custom-made latex gloves

Synthetic-based colorants have been extensively used in several industries, viz., cosmeceutical, feed, pharmaceuticals, food and textile. However, the growing awareness of potential teratogenicity, carcinogenicity and environmental concerns of certain synthetic colorants have expressed several limitations regarding their use in some products. These limitations, justifies the motivation to look for eco-friendly alternatives (cf., natural colorants) to be used as coloring agents for industrial applications. The filamentous fungi Talaromyces amestolkiae appeared as a promising source of natural fluorescent red colorant (NFRC) for the development of custom-made latex gloves. In this study, some basic colorant properties, including 3D-fluorescence and CIELAB color characteristics were first investigated systematically before their incorporation in natural rubber latex (NRL) films. The NFRC-NRL films properties were evaluated by physicochemical tests and toxicity through cell viability using 3T3 fibroblasts, wherein eluate of NFRC-NRL films (2.28 AU) revealed viability >70 % (exposing the biocompatibility). Regardless of the strategy proposed, it is shown as a proof-of-concept the potential application of NFRC in the NRL matrix as a biocompatible alternative to produce sustainable commercial colored custom-made latex gloves.

Improvement of betanin biosynthesis in Saccharomyces cerevisiae by metabolic engineering

Betanin is a member of natural pigment betacyanins family and has extensive application in the food industry as an important natural red food colorant. Its relatively inefficient production in nature however hampers access to this phytochemicals through traditional crop-based manufacturing. Microbial bioproduction therefore represents an attractive alternative. Here, we present the construction of a Saccharomyces cerevisiae strain for betanin production. Through minimizing metabolic crosstalk, screening and modifying biosynthetic enzymes, enhancing pathway flux and optimizing fermentation conditions, a final titer of betanin of 28.7 mg/L was achieved from glucose at 25 °C in baffled shake-flask, which is the highest reported titer produced by yeast to our knowledge. This work provides a promising step towards developing synthetic yeast cell factories for de novo biosynthesis of value-added betanin and other betacyanins.

Acylated anthocyanins: A review on their bioavailability and effects on postprandial carbohydrate metabolism and inflammation.

Anthocyanins, the natural red and purple colorants of berries, fruits, vegetables, and tubers, improve carbohydrate metabolism and decrease the risk factors of metabolic disorders, but their industrial use is limited by their chemical instability. Acylation of the glycosyl moieties of anthocyanins, however, changes the chemical properties of anthocyanins and provides enhanced stability. Thus, acylated anthocyanins are more usable as natural colorants and bioactive components of innovative functional foods. Acylated anthocyanins are common in pigmented vegetables and tubers, the consumption of which has the potential to increase the intake of health-promoting anthocyanins as part of the daily diet. For the first time, this review presents the current findings on bioavailability, absorption, metabolism, and health effects of acylated anthocyanins with comparison to more extensively investigated nonacylated anthocyanins. The structural differences between nonacylated and acylated anthocyanins lead to enhanced color stability, altered absorption, bioavailability, in vivo stability, and colonic degradation. The impact of phenolic metabolites and their potential health effects regardless of the low bioavailability of the parent anthocyanins as such is discussed. Here, purple-fleshed potatoes are presented as a globally available, eco-friendly model food rich in acylated anthocyanins, which further highlights the industrial possibilities and nutritional relevance of acylated anthocyanins. This work supports the academic community and industry in food research and development by reviewing the current literature and highlighting gaps of knowledge.

Identification of the Genes Coding for Carthamin Synthase, Peroxidase Homologs that Catalyze the Final Enzymatic Step of Red Pigmentation in Safflower (Carthamus tinctorius L.).

Carthamin, a dimeric quinochalcone that is sparingly soluble in water, is obtained from the yellow-orange corolla of fully blooming safflower (Carthamus tinctorius L.) florets. Carthamin is a natural red colorant, which has been used worldwide for more than 4500 years and is the major component of Japanese 'beni' used for dyeing textiles, in cosmetics and as a food colorant. The biosynthetic pathway of carthamin has long remained uncertain. Previously, carthamin was proposed to be derived from precarthamin (PC), a water-soluble quinochalcone, via a single enzymatic process. In this study, we identified the genes coding for the enzyme responsible for the formation of carthamin from PC, termed 'carthamin synthase' (CarS), using enzyme purification and transcriptome analysis. The CarS proteins were purified from the cream-colored corolla of safflower and identified as peroxidase homologs (CtPOD1, CtPOD2 and CtPOD3). The purified enzyme catalyzed the oxidative decarboxylation of PC to produce carthamin using O2, instead of H2O2, as an electron acceptor. In addition, CarS catalyzed the decomposition of carthamin. However, this enzymatic decomposition of carthamin could be circumvented by adsorption of the pigment to cellulose. These CtPOD isozymes were not only expressed in the corolla of the carthamin-producing orange safflower cultivars but were also abundantly expressed in tissues and organs that did not produce carthamin and PC. One CtPOD isozyme, CtPOD2, was localized in the extracellular space. Based on the results obtained, a model for the stable red pigmentation of safflower florets during flower senescence and the traditional 'beni' manufacturing process is proposed.

Production of Carminic Acid by Metabolically Engineered Escherichia coli.

Carminic acid is an aromatic polyketide found in scale insects (i.e., Dactylopius coccus) and is a widely used natural red colorant. It has long been produced by the cumbersome farming of insects followed by multistep purification processes. Thus, there has been much interest in producing carminic acid by the fermentation of engineered bacteria. Here we report the complete biosynthesis of carminic acid from glucose in engineered Escherichia coli. We first optimized the type II polyketide synthase machinery from Photorhabdus luminescens, enabling a high-level production of flavokermesic acid upon coexpression of the cyclases ZhuI and ZhuJ from Streptomyces sp. R1128. To discover the enzymes responsible for the remaining two reactions (hydroxylation and C-glucosylation), biochemical reaction analyses were performed by testing enzyme candidates reported to perform similar reactions. The two identified enzymes, aklavinone 12-hydroxylase (DnrF) from Streptomyces peucetius and C-glucosyltransferase (GtCGT) from Gentiana triflora, could successfully perform hydroxylation and C-glucosylation of flavokermesic acid, respectively. Then, homology modeling and docking simulations were performed to enhance the activities of these two enzymes, leading to the generation of beneficial mutants with 2-5-fold enhanced conversion efficiencies. In addition, the GtCGT mutant was found to be a generally applicable C-glucosyltransferase in E. coli, as was showcased by the successful production of aloesin found in Aloe vera. Simple metabolic engineering followed by fed-batch fermentation resulted in 0.63 ± 0.02 mg/L of carminic acid production from glucose. The strategies described here will be useful for the design and construction of biosynthetic pathways involving unknown enzymes and consequently the production of diverse industrially important natural products.

A Study of Producing Natural Red Color on Ikat Weaving Threads

The aims of this study are to find out what materials that used to produce red color on ikat weaving threads; what factors affect the making of red color on ikat weaving threads; the process of plants processing that used as a natural red colorant for the thread; and the kinds of red color produced from natural colorant plants. The samples were taken from the Kupang Regency area consists of three villages that are: Oesao, Sahraen, and Apraen village. The sample that took from three villages is Noni root, teak leaves, betel nut, and cherry fruit as the additional sample that was obtained from Dutalia Supermarket in Kupang city. The method that used in this study is the qualitative method with documenting technique and experiment. This study was done from January to March in the Biology Laboratorium of Universitas Kristen Artha Wacana, Kupang. The result of this study was found 11 red colors that produced from 4 kinds of plant that used for coloring the jark they are Noni root produced 4 colors (deep maroon, strawberry red, cardinal red, and terraccota. Cherry fruit produced 5 colors (coral pink, powder pink, hot pink, baby pink, and watermelon pink). Teak leaves produced the red-violet color and the last is Betel nut produced 2 colors (rust brown).

Utilization of the barberry extract in the confectionery products

In this study, the use of barberry fruit (Berberis crataegina DC.) extract was investigated as a natural red colorant in chewing gum, jelly, and marshmallow samples at different percentages (1%, 5%, and 10%). The color stability (ΔE) values were determined for all sample groups and it was observed that the barberry extract had higher color stability than beet juice concentrate, which was used in the control chewing gum samples as a natural red colorant. The water activity values were within the specified limits for all sample groups except the jelly samples and 10% colorant added chewing gum. The antioxidant and anti-radical properties of all the samples were significantly improved by the addition of the barberry extract. According to the results of the texture profile, the hardness values of all chewing gum and marshmallow samples decreased with the addition of barberry extract, and this decrease became even more important as the concentration increased.

Quality Assessment and Application of Red Natural Dye from Beetroot (Beta Vulgaris)

| Beet root (Beta vulgaris) is an excellent source of natural red colorant. In the present work red beet root dye was prepared in the powder form and then candies were prepared using this red beet root dye as food color. The stability studies of both, the prepared red beet dye and candies were performed at different storage conditions 4oC, 25oC, 45oC for eight weeks. Betanin content (%) was measured to evaluate the stability of color which showed the maximum retention of betanin content in red beet dye and candies stored at 4°C while lowest %age of betanin content was observed at 45°C showing that at higher temperatures the color is deteriorated. Stability in pH of red beet dye was also monitored at three different temperatures (4°C, 25°C and 45°C). Increase in pH was observed with increasing storage temperatures. Maximum stability of the color was observed at 4°C at most stable acidic pH and color degradation was observed with gradual increase in pH at 45°C. Microbiological analysis of candies and beet powder at 4°C and 25°C ensure that they are safe for consumption at both storage temperatures.

A natural colorant system from corn: Flavone-anthocyanin copigmentation for altered hues and improved shelf life

Anthocyanins are a major source of natural red colorants but currently face difficulties matching the hue range, stability, and affordability of synthetic options. Purple corn offers an FDA and EFSA-approved economical source of anthocyanin-based colorants. A C-glycosyl flavone and anthocyanin copigmentation system consisting of a flavone-rich anthocyanin-poor line and two anthocyanin-rich flavone-poor lines containing either pelargonidin or cyanidin-derived anthocyanins is described. This system offers a broad hue range and can improve stability. Cyanidin-rich model beverages had better stability than pelargonidin-rich beverages over time, but the addition of flavone-rich extract to both resulted in significantly longer half-lives (up to 50% longer). Flavone copigments produced hyperchromic and bathochromic shifts in both. A protective effect from flavone copigmentation was observed for glycosides. In contrast acylated forms displayed significantly shorter half-lives. Results suggest that corn C-glycosyl flavone-rich extracts could serve as a color enhancing and stabilizing agent for anthocyanin colorants.

Water-soluble fluorescent red colorant production by Talaromyces amestolkiae.

The replacement of synthetic colors in food products by natural alternatives has been boosted by consumers willing to pay more for healthier products. However, the success of microbial colorants depends not only on its acceptability on the market but also its production costs. Talaromyces species can produce water-soluble red colorants induced by glucose and monosodium glutamate (MSG). In this study, the influence of several conditions was evaluated to produce natural red colorants by submerged culture of Talaromyces amestolkiae. Under optimal conditions (g/L: glucose 10, MSG 25, MgSO4 0.012, FeSO4 0.01, CaCl2 0.015; and initial pH of 5.0), a 30-fold increase in the production was achieved, reaching a red colorant production of 13.44 UA500nm. Depending on the initial pH, colorants with different hues and chroma values were obtained. Deep yellow colorants were derived from neutral and basic pH, while deep red colors were derived from acidic pH. The fluorescence spectrum of culture broth obtained before and after complexation with salts presented red colorants with yellow fluorescence spectra. The information generated in this study would be useful for the formulation of industrial media for large-scale cultivation of T. amestolkiae, which have the potential to produce Talaromyces fermented colorants for use in health foods and pharmaceutics.

Porphyridum Cruentum as a natural colorant in chewing gum

Abstract In this study, usage possibility of the dried Porphyridium cruentum type microalga biomass in the chewing gum formulation as a natural colorant was investigated. For this aim, the effect of different spray dryer inlet temperatures (150-200 °C) on pigment (total carotenoid and chlorophyll-a) quantities and color properties ( L*, a*, b* and C*) of Porphyridium cruentum type microalga biomass were examined. P. cruentum were cultured using the tubular photobioreactor and harvested by centrifugation. The dried microalga was then added to chewing gum at different concentrations (0.5% and 1.0% w:w) as a natural red colorant. The amount of the total carotenoids in dried biomass ranged from 112.6 to 419.9 μg g -1 and chlorophyll-a from 511 to 1513 μg g-1. Considering sensorial analysis, algal taste increased with increasing microalga concentration ( p < 0.05). The studied factors had no significant effect on cohesiveness, (0.186-0.254), springiness (0.713-0.806) and resilience (0.014-0.015) parameters in chewing gums ( p < 0.05). However, a* value in chewing gum samples increased with drying temperature and usage amount (from 10.5 to 18.7) which increased red color intensity. According to the findings of the present study, it can be concluded that P. cruentum biomass had a potential use in chewing gum matrix.

Evaluation of the inhibition risk of shikonin on human and rat UDP-glucuronosyltransferases (UGT) through the cocktail approach

Shikonin, a natural red colorant, is widely used for food garnishment and cosmetic ingredient in the world. Shikonin also possesses a variety of pharmacological actions, including anti-inflammation and anti-cancer activities. However, little is known about its effects on the UDP-glucuronosyltransferases (UGT) activity. Therefore, the aim of this study was to evaluate the effect of shikonin on the UGT1A1, UGT1A3, UGT1A6, UGT1A9 and UGT2B7 activities via the human and rat liver microsomal assay and cocktail approach. The results showed shikonin inhibited human and rat liver microsomal UGT activity only in a dose-dependent manner. The further enzyme kinetic studies demonstrated that shikonin was not only a competitive inhibitor of human UGT1A1, UGT1A9, and UGT2B7, but also presented competitive inhibition on rat UGT1A1 and AZTG reactions. In conclusion, shikonin as a reversible inhibitor of UGT enzyme has a high-risk potential to cause the possible toxicity, especially drug-drug or food-drug interactions.