Investigation of repeated dose (90 day) oral toxicity, reproductive/developmental toxicity and mutagenic potential of 'Calebin A'

An Overview of the Pharmacological Properties of Calebin-A

The natural polyphenol, calebin-A, was recently discovered and identified as a novel phytopharmaceutical with anti-inflammatory, anti-tumor, and antiproliferative properties. Calebin-A occurs naturally in trace quantities in Curcuma longa/C cassia, commonly known as turmeric, from the Zingiberaceae family. Calebin-A is a curcumin analog or 'chemical cousin' of curcumin with a similar chemical structure. Although few research studies have been conducted on the pharmacological and therapeutic properties of calebin-A, it is a very promising molecule with a variety of pharmacological properties. Some studies have suggested that calebin-A is helpful in treating various cancers due to its inhibitory effect on cell growth and anti-inflammatory properties. Other studies have suggested that calebin-A may improve neurocognitive status associated with neurodegeneration caused by Alzheimer's disease (AD) by inhibiting the aggregation of β-amyloid. Finally, several studies have proposed that calebin-A may potentially be therapeutically beneficial in treating patients with obesity. This novel compound downregulates nuclear factor (NF)-κB-mediated processes involved with cancer, such as tumor cell invasion, proliferation, metastasis, and, most profoundly, inflammation. Moreover, calebin-A influences the activities of mitogen-activated protein kinases (MAPKs) in cancer cells. The present review identifies and discusses the pharmacological and phytochemical properties of calebin-A, as well as its therapeutic benefits and limitations, for future scientists and clinicians interested in exploring calebin-A's medicinal qualities.

Effect of Calebin-A on Critical Genes Related to NAFLD: A Protein-Protein Interaction Network and Molecular Docking Study

Background

Calebin-A is a minor phytoconstituent of turmeric known for its activity against inflammation, oxidative stress, cancerous, and metabolic disorders like Non-alcoholic fatty liver disease(NAFLD). Based on bioinformatic tools. Subsequently, the details of the interaction of critical proteins with Calebin-A were investigated using the molecular docking technique.

Methods

We first probed the intersection of genes/ proteins between NAFLD and Calebin-A through online databases. Besides, we performed an enrichment analysis using the ClueGO plugin to investigate signaling pathways and gene ontology. Next, we evaluate the possible interaction of Calebin-A with significant hub proteins involved in NAFLD through a molecular docking study.

Results

We identified 87 intersection genes Calebin-A targets associated with NAFLD. PPI network analysis introduced 10 hub genes (TP53, TNF, STAT3, HSP90AA1, PTGS2, HDAC6, ABCB1, CCT2, NR1I2, and GUSB). In KEGG enrichment, most were associated with Sphingolipid, vascular endothelial growth factor A (VEGFA), C-type lectin receptor, and mitogen-activated protein kinase (MAPK) signaling pathways. The biological processes described in 87 intersection genes are mostly concerned with regulating the apoptotic process, cytokine production, and intracellular signal transduction. Molecular docking results also directed that Calebin-A had a high affinity to bind hub proteins linked to NAFLD.

Conclusion

Here, we showed that Calebin-A, through its effect on several critical genes/ proteins and pathways, might repress the progression of NAFLD.

Calebin A modulates inflammatory and autophagy signals for the prevention and treatment of osteoarthritis

Introduction

Osteoarthritis (OA) is associated with excessive cartilage degradation, inflammation, and decreased autophagy. Insufficient efficacy of conventional monotherapies and poor tissue regeneration due to side effects are just some of the unresolved issues. Our previous research has shown that Calebin A (CA), a component of turmeric (Curcuma longa), has pronounced anti-inflammatory and anti-oxidative effects by modulating various cell signaling pathways. Whether CA protects chondrocytes from degradation and apoptosis in the OA environment (EN), particularly via the autophagy signaling pathway, is however completely unclear.

Methods

To study the anti-degradative and anti-apoptotic effects of CA in an inflamed joint, an in vitro model of OA-EN was created and treated with antisense oligonucleotides targeting NF-κB (ASO-NF-κB), and IκB kinase (IKK) inhibitor (BMS-345541) or the autophagy inhibitor 3-methyladenine (3-MA) and/or CA to affect chondrocyte proliferation, degradation, apoptosis, and autophagy. The mechanisms underlying the CA effects were investigated by MTT assays, immunofluorescence, transmission electron microscopy, and Western blot analysis in a 3D-OA high-density culture model.

Results

In contrast to OA-EN or TNF-α-EN, a treatment with CA protects chondrocytes from stress-induced defects by inhibiting apoptosis, matrix degradation, and signaling pathways associated with inflammation (NF-κB, MMP9) or autophagy-repression (mTOR/PI3K/Akt), while promoting the expression of matrix compounds (collagen II, cartilage specific proteoglycans), transcription factor Sox9, and autophagy-associated proteins (Beclin-1, LC3). However, the preventive properties of CA in OA-EN could be partially abrogated by the autophagy inhibitor 3-MA.

Discussion

The present results reveal for the first time that CA is able to ameliorate the progression of OA by modulating autophagy pathway, inhibiting inflammation and apoptosis in chondrocytes, suggesting that CA may be a novel therapeutic compound for OA.

A minor metabolite from Curcuma longa effective against metabolic syndrome: results from a randomized, double-blind, placebo-controlled clinical study

Metabolic syndrome (MetS) is characterized by the presence of at least three interrelated risk factors, including central obesity, hypertension, elevated serum triglycerides, low serum high-density lipoproteins, and insulin resistance. Abdominal obesity is considered a predominant risk factor. Lifestyle changes with medications to lower cholesterol, blood sugar, and hypertension are the general treatment approaches. Functional foods and bioactive food ingredients represent versatile tools for addressing different aspects of MetS. In a randomized placebo-controlled clinical study, we evaluated the effect of Calebin A, a minor bioactive phytochemical from Curcuma longa, on metabolic syndrome in obese adults (N = 100), and 94 individuals completed the study (N = 47 in both groups). They were subjected to Calebin A supplementation for 90 days, which resulted in a statistically significant reduction in their body weight, waist circumference, body mass index, low-density lipoprotein-cholesterol, and triglyceride levels compared to those with the placebo. A small but significant increase in high-density lipoprotein-cholesterol levels was also observed in these individuals. Furthermore, Calebin A showed a positive effect on adipokines by reducing circulating leptin levels. Finally, C-reactive protein levels were significantly reduced in Calebin A-supplemented individuals, suggesting a beneficial impact on managing MetS-induced inflammation. Blood glucose levels, insulin resistance, and blood pressure levels were not affected by Calebin A. In conclusion, Calebin A may be an effective supplement for managing abdominal obesity, dyslipidemia, and systemic inflammation in individuals with metabolic syndrome. This study was prospectively registered on the Clinical Trial Registry of India (CTRI) with the registration number CTRI/2021/09/036495. https://ctri.nic.in/Clinicaltrials/advancesearchmain.php.

Curcumin, calebin A and chemosensitization: How are they linked to colorectal cancer?

Colorectal cancer (CRC) is one of the leading malignant diseases worldwide with a high rate of metastasis and poor prognosis. Treatment options include surgery, which is usually followed by chemotherapy in advanced CRC. With treatment, cancer cells could become resistant to classical cytostatic drugs such as 5-fluorouracil (5-FU), oxaliplatin, cisplatin, and irinotecan, resulting in chemotherapeutic failure. For this reason, there is a high demand for health-preserving re-sensitization mechanisms including the complementary use of natural plant compounds. Calebin A and curcumin, two polyphenolic turmeric ingredients derived from the Asian Curcuma longa plant, demonstrate versatile anti-inflammatory and cancer-reducing abilities, including CRC-combating capacity. After an insight into their epigenetics-modifying holistic health-promoting effects, this review compares functional anti-CRC mechanisms of multi-targeting turmeric-derived compounds with mono-target classical chemotherapeutic agents. Furthermore, the reversal of resistance to chemotherapeutic drugs was presented by focusing on calebin A's and curcumin's capabilities to chemosensitize or re-sensitize CRC cells to 5-FU, oxaliplatin, cisplatin, and irinotecan. Both polyphenols enhance the receptiveness of CRC cells to standard cytostatic drugs converting them from chemoresistant into non-chemoresistant CRC cells by modulating inflammation, proliferation, cell cycle, cancer stem cells, and apoptotic signaling. Therefore, calebin A and curcumin can be tested for their ability to overcome cancer chemoresistance in preclinical and clinical trials. The future perspective of involving turmeric-ingredients curcumin or calebin A as an additive treatment to chemotherapy for patients with advanced metastasized CRC is explained.

Study on the Bioconversion of Curcumin to Calebin-A Using Spirulina subsalsa and Its Taxonomic Resolution Using 16S rRNA Analysis

Due to morphological convergence and the application of numerous taxonomic concepts, the systematics of filamentous cyanobacteria is still a significant problem. The incorporation and integration of modern molecular, cyto-morphological and ecological approaches in cyanobacterial taxonomy are essential and must be acknowledged as the valid methods for the development of their modern systematics. In this study, method of using 16S rRNA gene sequences to infer the genetic relationships of twelve freshwater cyanobacterial isolates amongst themselves was evaluated. The taxonomic resolution was inferred from their phylogenetic tree, in silico restriction digestion analysis and secondary structure prediction. These methods allowed cyanobacterial genera to be well distinguished with their genotypic and phenotypic differences. Amongst twelve strains, Spirulina subsalsa with highest protein content was used in this study for evaluating the stability of Curcumin which is a curcuminoid compound reported from Curcuma longa. Though they have wide properties, they still lack stability and bioavailability. It is reported previously that microbes are used for biotransformation and act as a carrier molecule. Therefore, in this study, Spirulina incorporated with curcumin resulted with pH stability of curcumin and were found to have a biotransformation into Calebin-A, curcuminoid compound originally present in smaller amount (0.005%) in C. longa with various biomedical applications.

Multifunctionality of Calebin A in inflammation, chronic diseases and cancer

Chronic diseases including cancer have high case numbers as well as mortality rates. The efficient treatment of chronic diseases is a major ongoing medical challenge worldwide, because of their complexity and many inflammatory pathways such as JNK, p38/MAPK, MEK/ERK, JAK/STAT3, PI3K and NF-κB among others being implicated in their pathogenesis. Together with the versatility of chronic disease classical mono-target therapies are often insufficient. Therefore, the anti-inflammatory as well as anti-cancer capacities of polyphenols are currently investigated to complement and improve the effect of classical anti-inflammatory drugs, chemotherapeutic agents or to overcome drug resistance of cancer cells. Currently, research on Calebin A, a polyphenolic component of turmeric (Curcuma longa), is becoming of growing interest with regard to novel treatment strategies and has already been shown health-promoting as well as anti-tumor properties, including anti-oxidative and anti-inflammatory effects, in diverse cancer cells. Within this review, we describe already known anti-inflammatory activities of Calebin A via modulation of NF-κB and its associated signaling pathways, linked with TNF-α, TNF-β and COX-2 and further summarize Calebin A's tumor-inhibiting properties that are known up to date such as reduction of cancer cell viability, proliferation as well as metastasis. We also shed light on possible future prospects of Calebin A as an anti-cancer agent.

A toxicity profile of the Pheroid® technology in rodents

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Acute administration of 2000 mg/kg of the Pheroid® delivery system was tolerated upon intravenous administration in BALB/c mice and Sprague-Dawley rats.

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Oral administration was tolerated in both acute toxicity evaluation (14-days post single dose administration) and during chronic administration (90-days dosing).

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No mutagenicity was present during the Ames assay.

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A statistically significant increase in creatinine levels in the sub-chronic female treatment group was observed, however no treatment related pathology was identified during histopathology.

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This evaluation did not identify any risk factors present for toxicity during oral or intravenous administration of the tested formulations during acute or repeated dosing.

The Pheroid® drug delivery system is now on the threshold of progressing into human clinical trials for various patented pharmaceutical applications and a systematic investigation of its toxicological properties in vitro and in vivo is thus a priority. Colloidal dispersions (nano- and microemulsions) demonstrate the ability to be adapted to accommodate either lipophilic, hydrophilic or amphiphilic drug molecules. The colloidal dispersions investigated during this evaluation has a general size of 200 nm - 2 μm, a zeta-potential of -25 mV and the main ingredient was ethyl esters of essential fatty acids.

The Ames mutagenicity assay was performed on selected Salmonella thyphimurium strains TA98, TA100 and TA102. The Ames assay included S9 metabolic activation and no mutagenicity was present during the assay. The effect of acute and subchronic administration on a biological system was investigated in two species of rodent (BALB/c mice and Sprague-Dawley rats). Observations focused on the physical condition, blood biochemical analysis and the haematological profiles. Gross necropsy was performed on all the test animals. Organ weights followed by histopathology of selected organ tissues were recorded.

During the acute evaluation animals showed tolerance of the maximum prescribed dose of 2000 mg/kg (according to OECD guidelines) in two rodent species after intravenous administration (absolute bioavaibility). The oral formulation was tolerated without incidents in both acute and subchronic studies. Although valuable baseline safety data was obtained regarding the Pheroid® system, future studies with the entrapped active pharmaceutical ingredients is necessary to provide a definitive safety profile.

Calebin-A, a Curcuminoid Analog Inhibits α-MSH-Induced Melanogenesis in B16F10 Mouse Melanoma Cells

Hyperpigmentation skin disorders comprise melasma, age spots, and post-inflammatory hyperpigmentation. They are characterized by an aberrant upregulation of melanin pigment and pose a significant burden aesthetically. Calebin-A (CBA) is a natural curcuminoid analog derived from turmeric root (Curcuma longa) but, unlike curcumin, it has not been explored yet for anti-melanogenic activity. Hence, in the current study, we studied CBA for its effects on α-melanocyte stimulating hormone (αMSH)-stimulated melanogenesis in B16F10 mouse melanoma cells. Our results showed that CBA (20 μM) significantly suppressed αMSH-stimulated melanogenesis after 48 h treatment. The underlying mechanisms of CBA’s anti-melanogenic activity were studied, and it was shown that CBA did not affect either intracellular tyrosinase activity or the direct activity of tyrosinase enzyme. Additionally, CBA did not affect intracellular α-glucosidase activity but significantly inhibited direct α-glucosidase activity. CBA also directly scavenged 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radicals, consistent with potent antioxidant activity but did not inhibit intracellular reactive oxygen species (ROS). CBA increased acidification of cellular organelles and inhibited maturation of melanosomes by significantly reducing the number of mature melanosomes. Our results indicate that CBA may hold promise as a pigmentation inhibitor for hyperpigmentation disorders for cosmetic use by targeting pathways other than tyrosinase inhibition. Further studies to delineate the molecular signaling mechanism of melanogenesis inhibition and test anti-melanogenesis efficacy of CBA in human skin melanocytes and skin equivalents are warranted.

Bioconversion of curcumin into calebin-A by the endophytic fungus Ovatospora brasiliensis EPE-10 MTCC 25236 associated with Curcuma caesia

Calebin-A is a curcuminoid compound reported to be present in Curcuma longa rhizome. The current study was aimed to isolate and characterize calebin-A from Curcuma caesia rhizome and its production through biotransformation approach using endophytic fungus. C. caesia rhizomes of different ages were subjected to analysis in order to investigate the age at which maximum calebin-A content is present. HP-TLC profiles, HPLC retention times and mass spectrometry detector confirmed the occurrence of calebin-A in C. caesia rhizomes of 12 to 14 months of age but not in rhizomes younger to 12 months. Furthermore, an endophytic fungus strain, EPE-10 that was isolated from the medicinal plant C. caesia was identified as Ovatospora brasiliensis based on morphological and molecular characteristics. This strain O. brasiliensis was deposited to the culture collected centre, MTCC Chandigarh, India under the Budapest treaty and was designated with the Accession Number MTCC 25236. Biotransformation process was carried out at 37 ± 0.5 °C with shaking for 7 days after addition of 0.01% w/v curcumin. Extraction of biotransformed products was done by following partition method and the extracts obtained were analyzed using HPTLC, HPLC and LCMS. The data of the study suggested that O. brasiliensis MTCC 25236 was found to convert curcumin to calebin-A in a time dependant manner with optimum conversion at 48 h. Furthermore, O. brasiliensis MTCC 25236 was found to be positive for the Baeyer-Villiger monooxygenase (BVMOs) enzyme activity which could possibly be the mechanism of this bioconversion. The results of this study for the first time indicated that the endophytic fungus identified as O. brasiliensis MTCC 25236 isolated from the C. caesia rhizome could be a possible source for naturally producing calebin-A.