Synonym name: Safranbitter; Saffronbitter
Catalogue No.: BP1097
Cas No.: 138-55-6
Formula: C₁₆H₂₆O₇
Mol Weight: 330.377
Botanical Source: saffron (stamens of Crocus sativus)

Purity: 95%~99%
Analysis Method: HPLC-DAD or/and HPLC-ELSD
Identification Method: Mass, NMR
Packing: Brown vial or HDPE plastic bottle
Can be supplied from milligrams to grams.

For Reference Standard and R&D, Not for Human Use Directly.
Inquire for bulk scale.

HPLC of Picrocrocin

HNMR of Picrocrocin

Storage conditions：Short-term storage at 2~8℃, long-term storage at -20 ~ -80℃

Introduction/Overview

Crocus sativus L., as a precious spice and medicinal plant with a long history, owes its unique color, flavor, and medicinal value mainly to a series of water-soluble carotenoid derivatives. Among them, crocin gives it a bright golden yellow color, while picrocrocin (also known as crocin, CAS number: 138-55-6) is the main source of saffron's characteristic bitter taste. For a long time, research has focused on the antioxidant, antidepressant, and neuroprotective activities of crocetin acid and saffron aldehyde (safranal, produced by the degradation of crocin). However, crocin itself, as the most abundant bitter glycoside component in saffron, has gradually gained attention from the international pharmacology community in recent years for its independent biological activity and pharmacological value.

Modern pharmacological research reveals that saffron bitterness is far more than just a flavor precursor substance. It exhibits various potential biological activities including anti-tumor, anti-inflammatory, and neuroprotective effects, especially in the field of anti-tumor. It shows significant growth inhibitory activity against multiple human cancer cell lines, such as SKMEL-2 human malignant melanoma cells, indicating its enormous potential as a new type of natural anti-tumor lead compound. However, compared to other components of saffron, a systematic review of saffron bitterness is still insufficient. This article aims to comprehensively review the chemical characteristics, plant sources, extraction methods, pharmacological activities, mechanisms of action, pharmacological evaluation, and clinical application prospects of saffron bitterness, in order to provide a systematic scientific reference for the in-depth research and development of this natural product.

Chemical structure and physicochemical properties

Saffron extract is a cyclic monoterpene glycoside, chemically classified as a degradation product of carotenoids. Its molecular formula is C16H26O7 and its molecular weight is 330.3770. The core of its structure is a cyclic monoterpene (crocin glycoside) containing an alkene bond, which is connected to a molecule of glucose through a glycosidic bond. This structure is the basis for its water solubility and bitterness characteristics.

The key physicochemical properties and pharmacological parameters are as follows:
* solubility Thanks to the presence of glucose groups, crocin has good water solubility (calculated value of about 21.4 mg/mL), which is beneficial for its absorption and distribution in organisms, but may also limit its transmembrane diffusion efficiency.
* Lipophilic nature The calculated LogP value is approximately -0.0337, indicating that it is an amphiphilic molecule with slightly higher hydrophilicity than lipophilicity, which is consistent with its glycosidic structure.
* Polar Surface Area The topologically polar surface area (TPSA) is as high as 116.45 Å ², mainly derived from multiple oxygen atoms (hydroxyl and sugar rings) in the molecule, which further confirms its strong polarity and affects its membrane permeability.
* Stability Saffron bitterness is relatively stable under dry and dark conditions, but it is prone to hydrolysis in aqueous solution, heating, or under the action of enzymes (such as β - glucosidase), removing the glucose group to generate unstable aglycones, which are then non enzymatically converted into the main aromatic component of saffron - saffron aldehyde. This transformation process has a significant impact on its biological activity, as it is not only the key to its flavor formation, but may also be related to some of its pharmacological effects, such as neuroprotection.
* Preliminary Safety Prediction Based on computational models, saffron bitterness shows a tendency towards lower blood-brain barrier permeability, which may affect its direct therapeutic effect on central nervous system diseases. However, its hERG inhibition risk prediction was negative ("no"), indicating a lower potential risk of cardiac toxicity. The Ames test predicted a value of 0.0, indicating that it may not have direct genetic toxicity, providing preliminary positive signals for its safety.

Plant sources and extraction methods

Saffron bitterness is a characteristic component of saffron stigma and is almost non-existent in other plants. Its content varies depending on the variety, origin, harvesting time, and processing and storage conditions of saffron, usually accounting for 1% to 13% of the dry stigma weight. It is the most abundant glycoside compound in saffron.

The extraction of crocin from saffron is mainly based on its polarity and water solubility characteristics. Common methods include:
1. Water extraction method The most traditional and commonly used method. By utilizing the good water solubility of saffron extract, it can be extracted with hot water or room temperature water. This method is simple, low-cost, and environmentally friendly, but its selectivity is poor. It can simultaneously extract multiple water-soluble components such as saffron acid, protein, and polysaccharides, which require complex separation and purification steps in the future.
2. Organic solvent extraction method Extract using methanol, ethanol, or ethanol water mixed solvents. Ethanol aqueous solutions (such as 70% -80% ethanol) are widely used due to their high efficiency in extracting crocin and low extraction of proteins and polysaccharides. The extraction efficiency of this method is usually higher than that of pure water, and the solvent is easy to recover.
3. Modern assisted extraction technology：
* Ultrasonic assisted extraction The use of ultrasonic cavitation effect to destroy plant cell walls, accelerate solvent penetration and component dissolution, can significantly shorten extraction time, reduce temperature, and improve yield.
* Microwave assisted extraction Microwave heating vaporizes water inside cells, creating pressure that rapidly ruptures the cells and efficiently releases target components. This method has the advantages of being fast, efficient, and energy-saving.
* Supercritical fluid extraction Mainly using supercritical CO ₂. Although this method has excellent extraction efficiency for non-polar components, its extraction efficiency for highly polar saffron bitters is limited, and often requires the addition of entrainers (such as ethanol) to increase yield, resulting in high equipment costs.

The crude extract after extraction usually needs further purification, and common techniques include macroporous adsorption resin chromatography (such as AB-8, D101 resin), silica gel column chromatography, preparative high-performance liquid chromatography, etc., to obtain high-purity saffron bitter extract for pharmacological research.

Pharmacological activity research

In recent years, in vitro and in vivo studies have confirmed that crocin has diverse biological activities.

1. Antitumor activity This is the pharmacological effect of saffron extract that has received the most attention. Research has confirmed that it has inhibitory effects on proliferation and induces apoptosis in various cancer cell lines.

   • melanoma As stated in the question, saffron extract has a clear growth inhibitory effect on SKMEL-2 human malignant melanoma cells. Research has shown that this effect is closely related to inducing cell cycle arrest (such as G2/M phase), activating caspase cascade reactions, regulating the Bcl-2/Bax protein ratio, and other apoptotic pathways.
   • colorectal cancer Research has shown that saffron extract can inhibit the growth of human colorectal cancer cells (such as HCT-116, HT-29) by inducing endoplasmic reticulum stress, mitochondrial dysfunction, and autophagy.
   • breast cancer For breast cancer cells such as MCF-7, crocin can inhibit cell proliferation and promote apoptosis by regulating PI3K/Akt, MAPK and other signaling pathways.
   • liver cancer In HepG2 and other liver cancer cells, crocin exhibits pro apoptotic and anti migratory invasion activities.
   • Other cancers It also shows varying degrees of inhibitory effects on cell lines such as lung cancer, prostate cancer, leukemia, etc.

2. Anti inflammatory and antioxidant activity Saffron extract can effectively scavenge free radicals such as DPPH and ABTS, demonstrating strong in vitro antioxidant capacity. In cellular and animal inflammation models (such as lipopolysaccharide induced macrophage inflammation model), it can downregulate the expression of pro-inflammatory factors (such as TNF - α, IL-1 β, IL-6, COX-2, iNOS), and its anti-inflammatory effect may be related to the inhibition of NF - κ B signaling pathway activation.

3. Neuroprotective activity Although its blood-brain barrier permeability is low, some studies suggest that crocin or its metabolites may be beneficial to the nervous system. In Alzheimer's disease cell models, it has shown the potential to reduce neurotoxicity induced by β - amyloid protein. Its degradation product saffron aldehyde has been widely proven to have anti anxiety, anti seizure, and neuroprotective effects, so saffron bitterness as a prodrug may also indirectly contribute to neuroprotective effects.

4. Other activities Preliminary studies also suggest that crocin may have the potential to have antidepressant, anti anxiety (possibly related to regulating the GABAergic system), hypoglycemic, and improved learning and memory abilities, but these effects require further in vivo experimental verification.

Mechanism of action and molecular targets

The pharmacological effects of saffron extract, especially its anti-tumor activity, are achieved by intervening in multiple cellular signaling pathways and molecular targets, reflecting the characteristics of multi-target action.

1. Inducing cell apoptosis This is the core mechanism of its anti-tumor effect.

   • Mitochondrial pathway By upregulating the pro apoptotic protein Bax and downregulating the anti apoptotic protein Bcl-2, the mitochondrial membrane potential decreases, cytochrome c is released, and caspase-9 and caspase-3 are activated, ultimately leading to cell apoptosis.
   • Death receptor pathway Possible activation of caspase-8 and initiation of exogenous apoptosis pathway through upregulation of Fas receptor, etc.
   • Endoplasmic reticulum stress pathway It can induce the expression of endoplasmic reticulum stress-related proteins (such as GRP78, CHOP), activate caspase-12, and participate in the process of apoptosis.

2. Block cell cycle Can block cancer cells at specific cell cycle checkpoints (such as G0/G1 phase or G2/M phase), preventing them from undergoing mitosis. This is usually associated with regulating the expression of cyclins and cyclin dependent kinases (CDKs), such as downregulating Cyclin B1, CDK1, etc.

3. Inhibit metastasis and invasion By downregulating the expression and activity of matrix metalloproteinases (MMPs, such as MMP-2 and MMP-9), cancer cells can inhibit their ability to degrade and migrate extracellular matrix.

4. Regulating key signaling pathways：

   • PI3K/Akt/mTOR pathway This is the core pathway for cell survival and proliferation. Saffron can inhibit cell proliferation and promote apoptosis by suppressing the phosphorylation of PI3K/Akt, thereby inhibiting its downstream target mTOR.
   • MAPK pathway It can regulate the phosphorylation status of MAPK family proteins such as ERK, JNK, p38, etc. Its activation of JNK and p38 usually promotes apoptosis, while inhibition of ERK inhibits proliferation.
   • NF - κ B pathway Highly activated in inflammation and tumors. Saffron extract can inhibit the degradation of I κ B α and p65 nuclear translocation, thereby suppressing the transcriptional activity of NF - κ B and reducing the expression of downstream pro-inflammatory and pro survival genes.
   • Nrf2/HO-1 pathway Plays a critical role in antioxidant stress. Saffron extract may exert cell protective effects by activating Nrf2 and upregulating the expression of antioxidant enzymes such as heme oxygenase-1 (HO-1).

5. Induce autophagy In some cancer cells, crocin can induce protective autophagy, but sustained or excessive autophagy may also lead to autophagic cell death, and its specific role is cell type and concentration dependent.

Evaluation of drug properties and pharmacokinetics

Although saffron bitterness has shown good biological activity, its drug like and pharmacokinetic (PK) properties are obstacles that must be overcome for its clinical application.

• absorb As a water-soluble glycoside, its oral absorption may be limited by the passive diffusion efficiency of intestinal epithelial cells. It may be partially absorbed by sodium dependent glucose transporters (SGLT1) or facilitated diffusion glucose transporters (GLUTs) in small intestinal epithelial cells, or it may be hydrolyzed by β - glucosidase in gut microbiota into aglycones and glucose, which are further converted into saffron aldehyde and absorbed. Therefore, its oral bioavailability may be low and vary greatly among individuals.
• distribution The computational model predicts low blood-brain barrier permeability, which limits its application in treating central nervous system diseases. Its distribution volume may be small, mainly distributed in blood and extracellular fluid.
• Metabolism The liver is its main metabolic site. In addition to possible hydrolysis reactions, the hepatic microsomal cytochrome P450 enzyme system (CYPs) may be involved in its oxidative metabolism. The combination reaction of glucuronidation and sulfation is also a possible metabolic pathway. Clarifying its metabolic enzyme profile is crucial for evaluating drug interactions.
• excretion Expected to be primarily excreted in urine through the kidneys in the form of prototypes or metabolites. Its polarity characteristics are beneficial for renal clearance.
• Challenges and Strategies in Drug Development：
  • challenge Low oral bioavailability due to strong water solubility but poor membrane permeability; Chemical stability issues (easily hydrolyzed); The complexity of effects and uncertainty of potential side effects caused by multi-target interactions.
  • Optimization Strategy：
    1. Structural modification Chemical modification of sugar or glycoside moieties, such as preparation of prodrugs (esterification, amidation to enhance lipid solubility), synthesis of analogues to improve membrane permeability, stability, and targeting.
    2. New drug delivery system Using nanotechnology, such as liposomes, polymer nanoparticles, solid lipid nanoparticles, etc., to encapsulate crocin can protect it from degradation, improve stability, enhance cellular uptake, achieve sustained and controlled release, and even targeted delivery (such as tumor EPR effect).
    3. combination therapy Combined with existing chemotherapy drugs such as 5-fluorouracil and cisplatin, it may produce a synergistic effect, reducing the dosage and toxic side effects of each drug.

At present, there is still a significant lack of preclinical pharmacokinetic studies on the crocin system (such as ADME studies in rats, dogs, and other animals), which is a gap that must be filled in future translational research.

Clinical application prospects and prospects

The research on saffron bitterness is still in the preclinical stage, but its multi-target anti-tumor and other activities have depicted broad prospects for its clinical application.

1. Potential application areas：

   • Tumor adjuvant therapy and chemoprevention As a natural product, it has relatively low toxicity and is expected to be developed as a chemopreventive or adjuvant therapy for tumors. It can be used in combination with conventional radiotherapy and chemotherapy to improve efficacy and reduce side effects (such as bone marrow suppression and neurotoxicity). Effective research on melanoma, colorectal cancer, and other diseases may become a priority breakthrough direction.
   • Inflammatory related diseases Based on its anti-inflammatory and antioxidant properties, it may be used to treat chronic inflammatory diseases such as inflammatory bowel disease, arthritis, etc.
   • Functional foods and health products As one of the main active ingredients of saffron, high-purity saffron bitters or standardized extracts can be used to develop high-end health products with functions such as anti fatigue, mood improvement, and anti-aging.

2. Future research directions：

   • In depth mechanism research Using proteomics, metabolomics, CRISPR-Cas9 gene editing, and other technologies to more accurately elucidate its direct targets (such as through drug affinity target stability analysis) and upstream and downstream signaling networks.
   • Systematic pharmacokinetic and toxicological evaluation Conduct animal pharmacokinetic and long-term toxicity tests that comply with Good Laboratory Practice (GLP) standards, clarify their safe dose window, target organ toxicity, and reversibility.
   • Pharmaceutical research Vigorously develop innovative formulations based on nanotechnology, solve their delivery efficiency issues, and explore local administration (such as topical treatment of melanoma), injection administration, and other routes.
   • clinical research After completing sufficient preclinical research, gradually advance Phase I (safety) and Phase II (efficacy exploration) clinical trials to ultimately verify its safety and efficacy in humans.
   • Synthetic Biology Production Given the scarcity and high cost of saffron resources, utilizing synthetic biology techniques to construct a biosynthetic pathway for saffron bitterness in microorganisms such as yeast and Escherichia coli, and achieving sustainable and low-cost industrial production, is the fundamental way to solve the bottleneck of raw materials.

Conclusion

Saffron bitterness, a long neglected characteristic bitter component of saffron, is attracting increasing scientific attention due to its unique chemical structure and diverse pharmacological activities, especially its clear anti-tumor effects. From a chemical structure perspective, it is a polar carotenoid glycoside; From a pharmacological perspective, it is a multi-target natural compound that exerts its effects by intervening in multiple pathways such as apoptosis, cycle, and inflammation. Although it faces challenges such as low bioavailability and stability in terms of pharmaceutical properties, the development of modern medicinal chemistry, pharmacy, and nanotechnology provides powerful tools to overcome these obstacles.

The current research has outlined a potential pathway for it to move from the laboratory to clinical practice. In the future, through in-depth interdisciplinary cooperation, saffron bitterness is expected to transform from a traditional spice ingredient into a modern drug or functional formulation for the prevention and treatment of major diseases such as tumors, based on elucidating its precise molecular mechanism, completing systematic preclinical evaluation, and developing efficient delivery systems. This fully interprets the natural drug development concept of "originating from tradition, surpassing tradition" and contributes new strength to human health. The research process also enlightens us that in-depth exploration of non major or characteristic components in traditional medicinal plants may discover unexpected drug lead compounds.