Biofunctionality of Carotenoid Metabolites: An Insight into Qualitative and Quantitative Analysis

Epidemiological and clinical studies have shown that dietary intake of carotenoid-rich fruits and vegetables is positively correlated with reduction in age-related eye diseases, atherosclerosis, certain cancers and chronic diseases. Carotenoids consist of unique chemical characteristics and are highly vulnerable to structural modifications, leading to the formation of various derivatives under physiological conditions. The identification of these molecules is necessary before addressing their biological functions. Carotenoid metabolomics is believed to be highly complex to fingerprint due to instability and interference with complex biological matrices. Noteworthy, progress has been made in understanding carotenoid metabolism or its biotransformation in biological samples. In this regard, the chapter highlights the concept of metabolomics and their related bio-analytical techniques pertaining to the detection of carotenoids and their derived products to elucidate their bio-transformation on targeted biological functions. Further, this chapter highlights the various hyphenated analytical tools and their optimization

Low-dose doxorubicin with carotenoids selectively alters redox status and upregulates oxidative stress-mediated apoptosis in breast cancer cells

The combination of carotenoids and doxorubicin (DOX) selectively alters oxidative stress-mediated apoptosis in breast cancer cells. Primarily, cytotoxic efficiency of carotenoids (β-carotene, BC; lutein, LUT; astaxanthin, AST; or fucoxanthin, FUCO) either with or without a minimal cytotoxic dose of DOX was evaluated in MCF-7 (0.12 μM) and MDA-MB-231 cells (0.28 μM). The higher cell growth inhibition of BC and/or LUT with DOX was selected for testing in further cell-based assays. Low-dose DOX significantly enhanced cytotoxicity in carotenoid (1 μM) or carotenoid (20 μM) treatment alone. Depleted glutathione, increased lipid peroxides and increased ROS levels in cells confirmed the cytotoxic effect. Furthermore, mitochondrial dysfunction, cell growth arrest at G0/G1 phase and caspase cascades as well as up- and down-regulated expression levels of related proteins (p21, p27, Bax, p53, Bcl-2, and cyclin D1) revealed the synergistic effect of carotenoid and DOX treatment on ROS-mediated apoptosis. These observations demonstrated increased apoptosis in BC + DOX/LUT + DOX-treated cells due to the pronounced pro-oxidant action. Interestingly, normal breast epithelial cells (MCF 10A) exposed to similar treatments resulted in non-significant cytotoxicity. These newly observed mechanistic differences of anticancer drugs on the mitigation of toxicity with carotenoids may provide insight into the targeting of cancer therapy

Fractionation and Characterization of Lycopene-Oxidation Products by LC-MS/MS (ESI)(+): Elucidation of the Chemopreventative Potency of Oxidized Lycopene in Breast-Cancer Cell Lines

Lycopene (LYC) has been correlated with the reduction of certain cancers and chronic diseases. However, the existence and biofunctionality of degraded, oxidized, and biotransformed LYC products in vivo have not been revealed. Therefore, this study aimed to screen and elucidate the potential bioactive lycopene-derived products in breast-cancer and noncancerous cells. LYC-oxidation or -cleavage products were generated using KMnO4. These oxidation products were separated as fractions I-III by silica column chromatography using gradient solvent systems. Further, LC-MS/MS (ESI)(+) was used to elucidate their possible fragmentation patterns and structures. Fraction II showed higher cytotoxicity (IC50 value of 64.5 mu M), cellular uptake, and apoptosis-inducing activity in MCF-7 cells. This fraction consists of major peak m/z 323, identified as apo-8,6'-carotendial. The cytotoxicity-inducing activity may be due to partial ROS generation with mitochondrial dysfunction. Further, the role of apo-8,6'-carotendial in the induction of apoptosis is demonstrated for the first time. These results illustrated that LYC-oxidation derivatives or metabolites are involved in growth inhibition of cancer cells. Exploration of specific oxidized-carotenoid products will give further insight into the field of nutritional biochemistry