Carotenoids in Drug Discovery and Medicine: Pathways and Molecular Targets Implicated in Human Diseases.

Carotenoids are isoprenoid-derived natural products produced in plants, algae, fungi, and photosynthetic bacteria. Most animals cannot synthesize carotenoids because the biosynthetic machinery to create carotenoids de novo is absent in animals, except arthropods. Carotenoids are biosynthesized from two C20 geranylgeranyl pyrophosphate (GGPP) molecules made from isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) via the methylerythritol 4-phosphate (MEP) route. Carotenoids can be extracted by a variety of methods, including maceration, Soxhlet extraction, supercritical fluid extraction (SFE), microwave-assisted extraction (MAE), accelerated solvent extraction (ASE), ultrasound-assisted extraction (UAE), pulsed electric field (PEF)-assisted extraction, and enzyme-assisted extraction (EAE). Carotenoids have been reported to exert various biochemical actions, including the inhibition of the Akt/mTOR, Bcl-2, SAPK/JNK, JAK/STAT, MAPK, Nrf2/Keap1, and NF-κB signaling pathways and the ability to increase cholesterol efflux to HDL. Carotenoids are absorbed in the intestine. A handful of carotenoids and carotenoid-based compounds are in clinical trials, while some are currently used as medicines. The application of metabolic engineering techniques for carotenoid production, whole-genome sequencing, and the use of plants as cell factories to produce specialty carotenoids presents a promising future for carotenoid research. In this review, we discussed the biosynthesis and extraction of carotenoids, the roles of carotenoids in human health, the metabolism of carotenoids, and carotenoids as a source of drugs and supplements.

Predicting the Anticancer Activity of 2-alkoxycarbonylallyl Esters against MDA-MB-231 Breast Cancer - QSAR, Machine Learning and Molecular Docking.

BACKGROUND: The continuous increase in mortality of breast cancer and other forms of cancer due to the failure of current drugs, resistance, and associated side effects calls for the development of novel and potent drug candidates. METHODS: In this study, we used the QSAR and extreme learning machine models in predicting the bioactivities of some 2-alkoxycarbonylallyl esters as potential drug candidates against MDA-MB-231 breast cancer. The lead candidates were docked at the active site of a carbonic anhydrase target. RESULTS: The QSAR model of choice satisfied the recommended values and was statistically significant. The R2pred (0.6572) was credence to the predictability of the model. The extreme learning machine ELM-Sig model showed excellent performance superiority over other models against MDAMB- 231 breast cancer. Compound 22 with a docking score of 4.67 kcal mol-1 displayed better inhibition of the carbonic anhydrase protein, interacting through its carbonyl bonds. CONCLUSION: The extreme learning machine's ELM-Sig model showed excellent performance superiority over other models and should be exploited in the search for novel anticancer drugs.

vHTS, 3-D Pharmacophore, QSAR and Molecular Docking Studies for the Identification of Phyto-derived ATP-Competitive Inhibitors of the BCR-ABL Kinase Domain.

BACKGROUND: Chronic myelogenous leukaemia (CML) constitutes about 15 % of adult leukaemia and is characterized by the overproduction of immature myeloid cells. METHODS: In this study, a virtual high throughput screening (vHTS) technique was employed to screen a library of phytochemicals of reported plants having anticancer activity. A docking score of -10 kcalmol-1 was used as the cut-off for the selection of phyto-compounds for pharmacophore-based virtual screening. Statistically robust and thoroughly validated QSAR model (R = 0.914, R2 = 0.836, Adjusted R2 = 0.764, LOO-CV= 0.6680) was derived for the inhibition of BCR-ABL kinase domain. RESULTS: The virtual screening, pharmacophore screening, QSAR model and molecular docking techniques applied herein revealed ellagic acid, a polyphenolic compound, as a potential competitive inhibitor of the BCR-ABL kinase domain. Ellagic acid binds to the inactive ABL state and forms similar interactions with key residues within the BCR-ABL Kinase domain as obtained in ponatinib (having inhibitory effects on the ABL thr-315I mutant). It forms hydrogen bond interaction with thr-315 residue (the gatekeeper residue). It is not likely to be prone to the various mutations associated with nilotinib because of its small size. CONCLUSION: The procedure of VHTs, Pharmacophore, QSAR, and molecular docking applied in this study could help in detecting more anti-CML compounds.

Carotenoid-Enriched Fractions From Spondias mombin Demonstrate HER2 ATP Kinase Domain Inhibition: Computational and In Vivo Animal Model of Breast Carcinoma Studies.

Human epidermal growth factor 2 (HER2) is overexpressed in about 20% of breast cancer and is associated with a poor prognosis. We report in this study that carotenoid-enriched fractions from Spondias mombin demonstrate HER2 ATP kinase domain inhibition. HER2 breast carcinoma was modeled in female Wistar rats and authenticated via immunohistochemical studies. Inhibition of HER2 ATP kinase domain by the carotenoid-enriched fractions was investigated by molecular docking, atomistic simulation, and the expression of HER2 mRNA in HER2-positive breast carcinoma model in female Wistar rats. The therapeutic efficacy of the treatments (carotenoid-rich fractions) was determined by biochemical, tumor volume, and histopathological analysis. Immunohistochemical analysis revealed 7,12-dimethylbenz[a]anthracene (DMBA)-induced HER2-positive breast carcinoma. Phytoconstituents of the carotenoid-enriched fractions astaxanthin, 7,7',8,8'-tetrahydro-ß,ß-carotene, beta-carotene-15,15'-epoxide, and lapatinib (standard drug) demonstrate inhibition of HER2 with docking scores of -3.0, -8.5, -11.5, and -10.6 kcal/mol, respectively; and during atomistic simulation, the compounds ruptured the canonical active-state K753/E770 salt-bridge interaction. The treatment similarly downregulated HER2 mRNA expression significantly at p < 0.05. It also upregulated the expression of p53 and p27 mRNAs significantly at p < 0.05 and reduced creatinine and urea concentrations in the serum at p < 0.05. The tumor volume was also significantly reduced when compared with that of the untreated group. Carotenoid-enriched fractions from S. mombin demonstrate anti-HER2 positive breast carcinoma potentials via HER2 ATP kinase domain inhibition.

In-silico HMG-CoA reductase-inhibitory and in-vivo anti-lipidaemic/anticancer effects of carotenoids from Spondias mombin.

OBJECTIVES: Inhibition of HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase, the rate rate-determining enzyme for the biogenesis of cholesterol is known to show antineoplastic effects. Therefore, this study investigates the in-silico HMG-CoA reductase (HMGCR)-inhibitory and in-vivo anti-lipidaemic/anticancer effects of carotenoids from Spondias mombin. METHODS: Carotenoids from S. mombin leaves were characterized with the aid of liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). The characterized phytochemicals were obtained from PubChem. They were docked into the orthosteric site of human HMGCR (Protein Data Bank code 1HW8) using AutoDock 4.0 suites. DMBA (7,12-dimethylbenz[a]anthracene) model of breast cancer was treated with the carotenoids extract from S. mombin (100 mg/kg and 200 mg/kg doses) to assess its anti-lipidaemic cum anticancer effects. KEY FINDINGS: Carotenoids from S. mombin; beta-carotene-15,15'-epoxide, astaxanthin and 7,7',8,8'-tetrahydro-ß-ß-carotene demonstrate HMGCR inhibition. They form hydrophobic interactions with key residues within the catalytic domain of HMGCR. The carotenoids extract exhibits anti-lipidaemic/anticancer effects, lowering serum triglyceride, LDL and cholesterol concentration. It increases HDL concentration and downregulates the expression of HMGR, AFP, CEACAM-3, BRCA-1 and HIF-1 mRNAs. CONCLUSION: Carotenoids from S. mombin demonstrate HMG-CoA reductase (HMGCR) inhibition, anti-lipidaemic, and anticancer effects. The inhibition of HMGCR by the carotenoids extract further poses it as a potential anti-hypercholesterolaemia compounds.

VEGFR-2 kinase domain inhibition as a scaffold for anti-angiogenesis: Validation of the anti-angiogenic effects of carotenoids from Spondias mombin in DMBA model of breast carcinoma in Wistar rats.

Vascular endothelial growth factor (VEGF) and its receptor-2 (VEGFR-2) mediated tumorigenesis, metastasis, and angiogenesis are the cause of the increased levels of mortality associated with breast cancer and other forms of cancer. Inhibition of VEGF and VEGFR-2 provides a great therapeutic option in the management of cancer. This study employed VEGFR-2 kinase domain inhibition as an anti-angiogenic scaffold and further validate the anti-angiogenic effects of the lead phytochemicals, carotenoids from Spondias mombin in 7, 12-Dimethylbenz[a]anthracene (DMBA) model of breast carcinoma in Wistar rats. Phytochemicals characterized from 6 reported anti-cancer plants were screened against the VEGFR-2 kinase domain. The lead phytochemicals, carotenoids from Spondias mombin were isolated and subjected to Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LC-ESI-MS) for characterization. The anti-angiogenic potentials of the carotenoid isolates were validated in the DMBA model of breast carcinoma in female Wistar rats through assessment of the expression of anti-angiogenic related mRNAs, histopathological analysis, and molecular docking. Treatment with carotenoid isolates (100 mg/kg and 200 mg/kg) significantly (p < 0.05) downregulated the expression of VEGF, VEGFR, Epidermal Growth Factor Receptor (EGFR), Hypoxia-Inducible Factor-1(HIF-1), and Matrix Metalloproteinase-2 (MMP-2) mRNAs in the mammary tumours, while the expression of Chromodomain Helicase DNA-Binding Protein-1 (CHD-1) mRNA was significantly (p < 0.05) upregulated. DMBA induced comedo and invasive ductal subtypes of breast carcinoma. The binding of astaxanthin, 7,7',8,8'-tetrahydro-ß,ß-carotene, and beta-carotene-15,15'-epoxide to the ATP binding site led to the DFG-out conformation with binding energies of -8.2 kcal/mol, -10.3 kcal/mol, and -10.5 kcal/mol respectively. Carotenoid isolates demonstrated anti-angiogenic and anti-proliferating potentials via VEGFR-2 kinase domain inhibition.

Carotenoid isolates of Spondias mombin demonstrate anticancer effects in DMBA-induced breast cancer in Wistar rats through X-linked inhibitor of apoptosis protein (XIAP) antagonism and anti-inflammation.

Breast cancer is the most prevalent cancer in women. X-linked inhibitor of apoptosis protein (XIAP) that is constantly overexpressed in cancer is a promising therapeutic target in cancer treatments. The mechanisms of the anticancer effects of carotenoid isolates of Spondias mombim in DMBA-induced breast cancer in Wistar rats through XIAP antagonism were investigated in the present study. Carotenoids isolated from the leaves of Spondias mombim were subjected to Liquid Chromatography/Mass Spectrometry (LC/MS) and Electrospray Ionization (ESI) for characterization. The characterized carotenoid isolates were docked against XIAP BIR2 domain and XIAP BIR3 domain. The anticancer effects of the carotenoid isolates of Spondias mombim in DMBA-induced breast cancer in Wistar rats were also investigated through the expression of XIAP, COX-2, TNF, BCl-2 mRNAs by qRT-PCR and biochemical parameters of catalase, lipid peroxidation, LDH, ALP, and ALT. These show the carotenoid isolates demonstrate anticancer effects by antagonism of XIAP, proapoptotic, and anti-inflammatory properties. PRACTICAL APPLICATIONS: The present study showed that carotenoids (astaxanthin, ß-carotene-15,15'-epoxide, and 7,7',8,8'-tetrahydro-ß, ß-carotene) isolated from the leaves of Spondias mombim are proapoptotic, it further gives credence to the chemopreventive abilities of carotenoids. This study validated XIAP as a druggable target in cancer treatment and hence more phytochemicals should be screened against it, for possible lead compounds of plant origin. Cancer cells often explore XIAP for antiapoptotic and resistance tendencies, hence, ß-carotene-15,15'-epoxide and 7,7',8,8'-tetrahydro-ß, ß-carotene (XIAP antagonists) are promising drug candidates that can withstand resistant and prone cancer cells to apoptotic cell death. There is a need to synthesize ß-carotene-15,15'-epoxide and 7,7',8,8'-tetrahydro-ß for further investigation in clinical studies.

Flavones scaffold of Chromolaena odorata as a potential xanthine oxidase inhibitor: Induced Fit Docking and ADME studies.

Introduction: Gout is a type of painful inflammation initiated by the interactions between monosodium urate crystals and connective tissue. Xanthine oxidase (XO) catalyzes the oxidation of hypoxanthine to xanthine, then to uric acid. The primary treatments for gout include XO inhibitors. At present, allopurinol is the most used XO inhibitor for the treatment of gout. However, it can cause adverse effects commonly known as allopurinol hypersensitivity syndrome, thereby limiting its usage. Consequently, it is necessary to develop potent and less toxic inhibitors of XO. Chromolaena odorata is one of such plants under investigation for its diverse health benefits. Methods: Phytochemicals of C. odorata were screened against XO receptor, using molecular docking. The top five hit compounds of glide docking yield flavones scaffold which were subjected to induced fit docking (IFD) and absorption, distribution, metabolism, and excretion (ADME) studies. Results: The result showed that flavones scaffold of C. odorata can bind with higher affinity and lower free energy values when compared to that of the standard, allopurinol. The IFD scores of the flavones scaffold range from -1525.25 to -1527.99 kcal/mol. Conclusion: Our results have shown that flavones scaffold might have the potential to act as an effective drug candidate when compared to allopurinol in treating and/or preventing gout and some inflammatory condition.