Decoding the phytochemical complexity of butterfly pea (Clitoria ternatea): A comprehensive review

Introduction

Clitoria ternatea, commonly referred to as butterfly pea, is a perennial herbaceous climber belonging to the Fabaceae family and is widely distributed throughout tropical and subtropical regions, particularly in South and Southeast Asia. The plant has been deeply rooted in traditional systems of medicine such as Ayurveda, where it is commonly known as "Aparajita" and is valued for its rejuvenating, memory-enhancing, and anxiolytic properties. Historically, different parts of the plant, including roots, leaves, seeds, and especially flowers, have been utilized for the treatment of various ailments ranging from neurological disorders and inflammation to infections and metabolic diseases. In addition to its medicinal uses, C. ternatea has gained increasing prominence in the food and beverage industry as a natural colorant due to the striking blue pigmentation of its flowers, which can change color depending on pH, making it highly attractive for functional and aesthetic applications in foods and drinks (Mukherjee et al., 2008; Kazuma et al., 2003) [11,16] . The growing interest in Clitoria ternatea is largely attributed to its rich and diverse phytochemical composition, which serves as the foundation for its wide range of pharmacological activities. Among the most significant bioactive compounds present in the plant are flavonoids and anthocyanins, particularly a unique group of polyacylated anthocyanins known as ternatins. These compounds are responsible not only for the vibrant blue coloration of the flowers but also for their potent antioxidant properties. Ternatins have been shown to effectively scavenge free radicals, inhibit lipid peroxidation, and protect cellular components from oxidative damage, thereby playing a crucial role in preventing oxidative stress-related diseases such as cardiovascular disorders, neurodegenerative conditions, and certain types of cancer (Kazuma et al., 2003; Jeyaraj et al., 2022) [8,11] . In addition to anthocyanins, other flavonoids such as quercetin, kaempferol, and myricetin derivatives further enhance the antioxidant and anti-inflammatory potential of the plant by modulating International Journal of Agriculture and Food Science https://www.agriculturaljournals.com key cellular signaling pathways and reducing the production of pro-inflammatory mediators (Sahu et al., 2023) [26] . Beyond flavonoids, C. ternatea contains a variety of other phytoconstituents, including alkaloids, glycosides, saponins, tannins, and phenolic acids, each contributing to its multifaceted biological activities. Alkaloids such as clitorin and aparajitin have been associated with neuropharmacological effects, supporting the traditional use of the plant as a cognitive enhancer and nervine tonic. Experimental studies have demonstrated that extracts of C. ternatea can improve memory, learning, and cognitive performance, potentially through modulation of cholinergic activity and enhancement of acetylcholine levels in the brain (Mukherjee et al., 2008; Rai et al., 2002) [16,25] . Phenolic compounds, including gallic acid and p-coumaric acid, further contribute to the plant's antioxidant capacity and play a role in reducing inflammation and protecting against chronic diseases (Sahu et al., 2023) [26] . Saponins and tannins present in the plant exhibit antimicrobial and antidiabetic properties, with saponins known to improve glucose metabolism and lipid profiles, while tannins exert astringent and antimicrobial effects (Jeyaraj et al., 2022) [8] . One of the most distinctive and scientifically intriguing aspects of Clitoria ternatea is the presence of cyclotides, a class of cyclic peptides characterized by a unique cystine knot structure that imparts exceptional stability against thermal, chemical, and enzymatic degradation. Cyclotides such as cliotides have attracted considerable attention due to their diverse biological activities, including antimicrobial, antiviral, insecticidal, and cytotoxic effects. Their remarkable stability and bioactivity make them promising candidates for pharmaceutical development, particularly in the design of novel peptide-based therapeutics (Poth et al., 2011; Craik et al., 1999) [3,23] . The discovery of cyclotides in C. ternatea has opened new avenues for research into plant-derived bioactive peptides and their potential applications in medicine and agriculture. The pharmacological properties of C. ternatea are extensive and have been validated through numerous in vitro and in vivo studies. Its antioxidant activity is one of the most well-documented effects, with various extracts demonstrating strong radical scavenging capacity and protective effects against oxidative stress-induced cellular damage (Jeyaraj et al., 2022; Sahu et al., 2023) [8,26] . The antiinflammatory activity of the plant is mediated through the inhibition of inflammatory mediators such as prostaglandins, cytokines, and nitric oxide, thereby reducing inflammation and associated tissue damage. Additionally, the plant exhibits significant antimicrobial activity against a broad spectrum of bacterial and fungal pathogens, supporting its traditional use in treating infections (Kamkaen & Wilkinson, 2009) [9] . The neuroprotective and nootropic effects of Clitoria ternatea are particularly noteworthy, as they align closely with its traditional use as a brain tonic. Studies have shown that the plant can enhance memory and learning, reduce anxiety, and protect against neurodegenerative changes, possibly through antioxidant mechanisms and modulation of neurotransmitter systems (Rai et al., 2002; Mukherjee et al., 2008) [16,25] . Furthermore, emerging evidence suggests that C. ternatea may possess antidiabetic properties, with extracts demonstrating the ability to lower blood glucose levels, improve insulin sensitivity, and inhibit carbohydratedigesting enzymes such as α-amylase and α-glucosidase (Chusak et al., 2018) [2] . These findings highlight the potential of the plant as a natural therapeutic agent for the management of diabetes and related metabolic disorders. In addition to its medicinal applications, Clitoria ternatea has gained considerable attention in the food and nutraceutical industries. The anthocyanin-rich extracts of the flowers are increasingly being used as natural food colorants, offering a safer and more sustainable alternative to synthetic dyes. The pH-sensitive color-changing property of ternatins further enhances their appeal in innovative food products and beverages. Moreover, the incorporation of C. ternatea into functional foods and dietary supplements is being explored due to its health-promoting properties, including antioxidant and anti-inflammatory effects (Chayaratanasin et al., 2015) [1] . Overall, the integration of traditional knowledge with modern scientific research has established Clitoria ternatea as a plant of significant pharmacological and industrial importance. Its rich phytochemical profile, encompassing flavonoids, anthocyanins, alkaloids, phenolics, and cyclotides, underlies its diverse biological activities and therapeutic potential. As research continues to uncover new insights into its mechanisms of action and potential applications, C. ternatea stands out as a promising candidate for the development of novel nutraceuticals, functional foods, and pharmaceutical agents. The growing body of evidence not only validates its traditional uses but also highlights its relevance in addressing contemporary health challenges, making it an important subject of ongoing and future scientific investigation.

Chemical Composition of Clitoria ternatea

The chemical constituents of C. ternatea can be broadly classified into polyphenols, flavonoids, anthocyanins, alkaloids, terpenoids, peptides, and other secondary metabolites. [11,31] [16] Glycosides Flavonol glycosides, anthocyanin glycosides

Leaves, flowers

Enhance solubility and biological activity of flavonoids Kazuma et al., 2003 [11] Terpenoids [20,23] Proteins & Amino Acids Albumin-like proteins, enzyme butelase-1 Seeds, pods Involved in peptide cyclization; important in biotechnology Nguyen et al., 2011 [20] Saponins Triterpenoid saponins (various) Roots, leaves

Contribute to antidiabetic and cholesterol-lowering effects Jeyaraj et al., 2022 [8] Tannins

Anthocyanins (Major Pigments)

Anthocyanins represent the most distinctive and extensively studied class of phytochemicals in Clitoria ternatea flowers, primarily responsible for their intense and deep blue coloration. These pigments are predominantly present as polyacylated anthocyanins known as ternatins, which are structurally derived from delphinidin and further modified by glycosylation and acylation with aromatic acids. Major ternatins such as ternatin A1, A2, B1, and D1 contribute significantly to the stability and vivid hue of the flower extract. The polyacylation of these anthocyanins enhances their molecular stability against environmental factors such as light, heat, and pH changes, distinguishing them from less stable anthocyanins found in other plants. In addition to their coloring properties, these compounds exhibit potent antioxidant activity by effectively scavenging reactive oxygen species and inhibiting oxidative damage at the cellular level. A unique and commercially valuable feature of ternatins is their pH-sensitive color variation, where the pigment shifts from deep blue in neutral conditions to purple and pink under acidic environments, making them highly suitable as natural food colorants and pH indicators in functional foods and beverages. This property has led to their increasing application in the food industry as safer alternatives to synthetic dyes, while also offering additional health benefits associated with their bioactive nature (Kazuma et al., 2003; Terahara et al., 1989; Gamage et al., 2021) [4,11,31] .

Flavonoids and Flavonol Glycosides

Flavonoids constitute a major class of phenolic compounds in Clitoria ternatea and play a crucial role in its biological and pharmacological activities. The plant contains several wellcharacterized flavonoids, including kaempferol, quercetin, myricetin, and their glycosidic derivatives such as kaempferol-3-glucoside and quercetin-3-glucoside. These compounds are predominantly present in glycosylated forms, which enhance their solubility, stability, and bioavailability within plant tissues and biological systems. Flavonoids in C. ternatea are recognized for their strong antioxidant properties, primarily through their ability to donate hydrogen atoms or electrons to neutralize reactive oxygen species and thereby prevent oxidative stress-induced cellular damage. In addition to antioxidant activity, these compounds exhibit significant anti-inflammatory effects by modulating key signaling pathways such as NF-κB and inhibiting the production of pro-inflammatory mediators, including cytokines and enzymes like cyclooxygenase. The synergistic interaction of these flavonoids further enhances the overall therapeutic potential of the plant, supporting its traditional use in managing inflammatory and oxidative stress-related disorders (Saito et al., 1985; Kazuma et al., 2003; Jeyaraj et al., 2020) [5,8,11,28] .

Phenolic Compounds (Polyphenols)

Polyphenols are widely distributed throughout Clitoria ternatea and represent an important group of bioactive constituents contributing to its therapeutic potential. This class primarily includes phenolic acids, phenolic alcohols, and various cinnamic acid derivatives, which are known for their strong antioxidant properties. Common phenolic acids such as gallic acid, caffeic acid, and p-coumaric acid have been identified in different parts of the plant and are recognized for their ability to donate hydrogen atoms or electrons, thereby neutralizing reactive oxygen species and preventing oxidative damage to cellular components. Phenolic alcohols further enhance this protective effect by stabilizing free radicals and interrupting chain reactions involved in lipid peroxidation. Cinnamic acid derivatives, on the other hand, contribute not only to antioxidant activity but also to anti-inflammatory and antimicrobial effects through modulation of enzymatic and signaling pathways. The collective action of these polyphenolic compounds plays a crucial role in reducing oxidative stress, which is a key factor in the pathogenesis of chronic diseases such as cardiovascular disorders, diabetes, and neurodegenerative conditions. Thus, the rich polyphenolic profile of C. ternatea supports its growing application in nutraceuticals and functional foods aimed at promoting health and preventing disease (Multisona et al., 2023; Sahu et al., 2023) [17,26] .

Alkaloids

Alkaloids are an important group of nitrogen-containing secondary metabolites present in Clitoria ternatea, contributing significantly to its pharmacological profile.

Although the alkaloid content of the plant is less extensively characterized compared to its flavonoid and anthocyanin fractions, compounds such as clitorin have been reported, along with other partially identified or unidentified alkaloidal constituents. These compounds are believed to play a key role in the plant's neuropharmacological effects, particularly in relation to its traditional use as a brain tonic in Ayurvedic medicine. Experimental studies suggest that alkaloids in C. ternatea may exert neuroprotective and cognitive-enhancing effects by modulating neurotransmitter systems, especially the cholinergic pathway, which is crucial for memory and learning processes. Additionally, these compounds may help reduce oxidative stress in neural tissues and protect against neurodegenerative changes by enhancing antioxidant defenses and inhibiting neuronal damage. The presence of such alkaloidal fractions supports the plant's reported benefits in improving memory, reducing anxiety, and enhancing overall cognitive function, thereby reinforcing its potential application in the management of neurological disorders (Mohan, 2013; Sahu et al., 2023) [13,26] .

Terpenoids and Phytosterols

Lipophilic constituents of Clitoria ternatea include phytosterols such as β-sitosterol, stigmasterol, and campesterol, along with triterpenoids like taraxerol, which collectively contribute to the plant's pharmacological activities. These compounds are typically localized in lipidrich fractions of the plant and play important roles in maintaining cellular integrity and modulating biological functions. Phytosterols structurally resemble cholesterol and are known to competitively inhibit its intestinal absorption, thereby contributing to cholesterol-lowering effects and improved lipid profiles. In addition, β-sitosterol and stigmasterol exhibit notable anti-inflammatory activity by suppressing pro-inflammatory mediators such as cytokines and prostaglandins. Taraxerol, a pentacyclic triterpenoid, further enhances these effects through its ability to stabilize cellular membranes, reduce oxidative stress, and inhibit inflammatory pathways. The lipophilic nature of these compounds also facilitates their interaction with biological membranes, improving membrane fluidity and protecting cells from damage. Altogether, these bioactive lipophilic molecules support the therapeutic potential of C. ternatea in managing inflammation, hyperlipidemia, and related metabolic disorders (Multisona et al., 2023; Sahu et al., 2023) [17, 26] .

Cyclotides (Bioactive Peptides)

One of the most distinctive chemical features of Clitoria ternatea is the presence of cyclotides, a unique class of cyclic peptides characterized by a head-to-tail cyclized backbone and a cystine knot motif that confers extraordinary structural stability. Among these, kalata-type cyclotides are particularly prominent and share structural similarities with the wellstudied kalata B1, while C. ternatea also contains butelaseassociated peptides linked to the enzyme butelase-1, which plays a crucial role in peptide cyclization. These cyclotides exhibit a wide range of biological activities, including potent antimicrobial effects against bacteria, fungi, and viruses, as well as insecticidal properties that contribute to the plant's natural defense mechanisms. Their remarkable resistance to thermal, chemical, and enzymatic degradation makes them highly stable even under harsh physiological conditions, distinguishing them from most linear peptides. Due to these properties, cyclotides are increasingly recognized as [21,22,23] .

Saponins and Glycosides

Clitoria ternatea contains a range of triterpenoid saponins and glycosidic compounds that significantly contribute to its biological activities. Triterpenoid saponins are amphiphilic molecules composed of a triterpene aglycone linked to sugar moieties, which enhance their solubility and bioavailability. These compounds are known for their strong antioxidant potential, primarily through their ability to scavenge free radicals, inhibit lipid peroxidation, and protect cellular components from oxidative damage. In addition, saponins exhibit notable immunomodulatory effects by stimulating or regulating immune responses, including the activation of macrophages, modulation of cytokine production, and enhancement of antibody responses. Glycosidic compounds present in C. ternatea, including flavonoid and other secondary metabolite glycosides, further contribute to these effects by improving compound stability and facilitating interaction with biological targets. Together, these constituents support the plant's traditional use in boosting immunity and protecting against oxidative stress-related disorders, highlighting its potential application in nutraceutical and therapeutic formulations (Mohan, 2013; Sahu et al., 2023) [13,26] .

Tannins and Resins

Clitoria ternatea contains both hydrolyzable and condensed tannins, along with resinous compounds, which contribute significantly to its antimicrobial and astringent properties. Hydrolyzable tannins, composed of gallic or ellagic acid esters, and condensed tannins (proanthocyanidins) are known for their ability to bind proteins and precipitate microbial enzymes, thereby inhibiting the growth of bacteria and fungi. These tannins also exert astringent effects by forming complexes with proteins in tissues, leading to contraction and tightening of mucosal surfaces, which is beneficial in wound healing and in controlling diarrhea and minor infections. Resinous compounds present in the plant further enhance antimicrobial activity by disrupting microbial cell membranes and interfering with metabolic processes. The combined action of tannins and resins not only protects the plant against pathogens but also supports its traditional use in treating infections and inflammatory conditions. These properties highlight the therapeutic relevance of C. ternatea in herbal medicine and its potential application in developing natural antimicrobial agents (Mohan, 2013; Sahu et al., 2023) [13, 26] .

Nutritional and Mineral Components

Apart from its rich phytochemical profile, Clitoria ternatea flowers also possess notable nutritional constituents that enhance their value as a functional food ingredient. The flowers contain essential macronutrients such as proteins, carbohydrates, and dietary fiber, which contribute to basic nutritional requirements and support overall metabolic health. Proteins present in the flowers may provide amino acids necessary for tissue repair and physiological functions, while carbohydrates serve as an immediate energy source. Dietary fiber plays a crucial role in promoting digestive health, regulating bowel movements, and aiding in glycemic control by slowing glucose absorption. In addition to these macronutrients, the flowers are a source of important minerals, including calcium, magnesium, and potassium. Calcium is essential for bone health and cellular signaling, magnesium acts as a cofactor in numerous enzymatic reactions and supports neuromuscular function, and potassium is vital for maintaining electrolyte balance and cardiovascular health. The presence of these nutrients, combined with bioactive compounds, makes C. ternatea an excellent candidate for incorporation into functional foods and nutraceutical products aimed at improving health and preventing disease (Sahu et al., 2023; Chayaratanasin et al., 2015) [1,26] .

Conclusion

In conclusion, Clitoria ternatea stands out as a chemically diverse and pharmacologically significant medicinal plant, owing to its rich repertoire of bioactive compounds such as anthocyanins (particularly ternatins), flavonoids, and cyclotides. These constituents collectively underpin a wide spectrum of biological activities, including antioxidant, antiinflammatory, antimicrobial, neuroprotective, and metabolic regulatory effects, thereby validating its long-standing use in traditional medicine. The presence of highly stable, polyacylated anthocyanins not only contributes to its distinctive coloration but also supports its growing application as a natural food colorant with added health benefits. Moreover, the discovery of cyclotides structurally robust cyclic peptides with remarkable resistance to degradation opens new avenues for the development of novel peptide-based therapeutics. Beyond medicinal applications, the integration of C. ternatea into functional foods, nutraceuticals, and cosmetic formulations highlights its multidisciplinary relevance. Overall, the convergence of traditional knowledge and modern scientific validation positions Clitoria ternatea as a promising natural resource with substantial potential in advanced drug development and innovative functional product industries.

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