Potent anti-angiogenic activity of B19--a mono-carbonyl analogue of curcumin

Perspectives for synthetic curcumins in chemoprevention and treatment of cancer: An update with promising analogues

Curcumin, a pure compound extracted from the flowering plant, turmeric (Curcuma longa. Zingiberaceae), is a common dietary ingredient found in curry powder. It has been studied extensively for its anti-inflammatory, antioxidant, antimicrobial and anti-tumour activities. Evidence is accumulating demonstrating its potential in chemoprevention and as an anti-tumour agent for the treatment of cancer. Despite demonstrated safety and tolerability, the clinical application of curcumin is frustrated by its poor solubility, metabolic instability and low oral bioavailability. Consequently researchers have tried novel techniques of formulation and delivery as well as synthesis of analogues with enhanced properties to overcome these barriers. This review presents the synthetic analogues of curcumin that have proven their anticancer potential from different studies. It also highlights studies that combined these analogues with approved chemotherapies and delivered them via novel techniques. Currently, there are no reports of clinical studies on any of the synthetic congeners of curcumin and this presents an opportunity for future research. This review presents the synthetic analogues of curcumin and makes a compelling argument for their potential application in the management of cancerous disease.

Monocarbonyl curcumin analog A2 potently inhibits angiogenesis by inducing ROS-dependent endothelial cell death

Excessive and abnormal vessel growth plays a critical role in the pathogenesis of many diseases, such as cancer. Angiogenesis is one of the hallmarks of cancer growth, invasion, and metastasis. Discovery of novel antiangiogenic agents would provide new insights into the mechanisms of angiogenesis, as well as potential drugs for cancer treatment. In the present study, we investigated the antiangiogenic activity of a series of monocarbonyl analogs of curcumin synthesized previously in our lab. We found that curcumin analog A2 displayed the full potential to be developed as a novel antiangiogenic agent. Curcumin analog A2 at and above 20 μM dramatically inhibited the migration and tube formation of human umbilical vein endothelial cells (HUVECs) in vitro, new microvessels sprouting from the rat aortic rings ex vivo and newly formed microvessels in chicken chorioallantoic membranes (CAMs) and Matrigel plus in vivo. We further demonstrated that curcumin analog A2 exerted its antiangiogenic activity mainly through inducing endothelial cell death via elevating NADH/NADPH oxidase-derived ROS. Curcumin analog A2 at the antiangiogenic concentrations also triggered autophagy in HUVECs, but this process is neither a pre-requisite for toxicity, leading to the cell death nor a protective response against the toxicity of curcumin analog A2. In conclusion, we demonstrate for the first time the potent antiangiogenic activity of the monocarbonyl curcumin analog A2, which could serve as a promising potential therapeutic agent for the prevention and treatment angiogenesis-related diseases, such as cancer.

Curcumin Analogue CA15 Exhibits Anticancer Effects on HEp-2 Cells via Targeting NF-κB

Laryngeal carcinoma remains one of the most common malignancies, and curcumin has been proven to be effective against head and neck cancers in vitro. However, it has not yet been applied in clinical settings due to its low stability. In the current study, we synthesized 34 monocarbonyl analogues of curcumin with stable structures. CA15, which exhibited a stronger inhibited effect on laryngeal cancer cells HEp-2 but a lower toxicity on hepatic cells HL-7702 in MTT assay, was selected for further analysis. The effects of CA15 on cell viability, proliferation, migration, apoptosis, and NF-κB activation were measured using MTT, Transwell migration, flow cytometry, Western blot, and immunofluorescence assays in HEp-2 cells. An NF-κB inhibitor, BMS-345541, as well as curcumin was also tested. Results showed that CA15 induced decreased toxicity towards HL-7702 cells compared to curcumin and BMS-345541. However, similar to BMS-345541 and curcumin, CA15 not only significantly inhibited proliferation and migration and induced caspase-3-dependent apoptosis but also attenuated TNF-α-induced NF-κB activation in HEp-2 cells. These results demonstrated that curcumin analogue CA15 exhibited anticancer effects on laryngeal cancer cells via targeting of NF-κB.

Eliminating the heart from the curcumin molecule: monocarbonyl curcumin mimics (MACs)

Curcumin is a natural product with several thousand years of heritage. Its traditional Asian application to human ailments has been subjected in recent decades to worldwide pharmacological, biochemical and clinical investigations. Curcumin’s Achilles heel lies in its poor aqueous solubility and rapid degradation at pH ~ 7.4. Researchers have sought to unlock curcumin’s assets by chemical manipulation. One class of molecules under scrutiny are the monocarbonyl analogs of curcumin (MACs). A thousand plus such agents have been created and tested primarily against cancer and inflammation. The outcome is clear. In vitro, MACs furnish a 10–20 fold potency gain vs. curcumin for numerous cancer cell lines and cellular proteins. Similarly, MACs have successfully demonstrated better pharmacokinetic (PK) profiles in mice and greater tumor regression in cancer xenografts in vivo than curcumin. The compounds reveal limited toxicity as measured by murine weight gain and histopathological assessment. To our knowledge, MAC members have not yet been monitored in larger animals or humans. However, Phase 1 clinical trials are certainly on the horizon. The present review focuses on the large and evolving body of work in cancer and inflammation, but also covers MAC structural diversity and early discovery for treatment of bacteria, tuberculosis, Alzheimer’s disease and malaria.