ABSTRACT
Vitamin D3 metabolites block lipid biosynthesis by promoting degradation of the complex of sterol regulatory element-binding protein (SREBP) and SREBP cleavage-activating protein (SCAP) independent of their effects on the vitamin D receptor (VDR). We previously reported the development of KK-052, the first vitamin D-based SREBP inhibitor that mitigates hepatic lipid accumulation without VDR-mediated calcemic action in mice. Herein we extend our previous work to synthesize KK-052 analogues. Various substituents were introduced to the phenyl ring of KK-052, and two KK-052 analogues were found to exhibit more potent SREBP/SCAP inhibitory activity than KK-052, whereas they all lack VDR activity. These new KK-052 analogues may be suited for further development as VDR-silent SREBP/SCAP inhibitors.
ABSTRACT
Three novel analogues of C22-fluoro-25-hydroxyvitamin D3 (5-7) were synthesized and evaluated to investigate the effects of side-chain fluorination on biological activity and metabolism of vitamin D. These novel analogues were constructed by convergent synthesis applying the Wittig-Horner coupling reaction between CD-ring ketones (41,42,44) and A-ring phosphine oxide (11). The introduction of C22-fluoro units was achieved by stereoselective deoxy-fluorination for synthesizing 5 and 6 or two-step cationic fluorination for 7. The absolute configuration of the C22-fluoro-8-oxo-CD-ring (39) was confirmed by X-ray crystallographic structure determination. The basic biological activity of the side-chain fluorinated analogues, including compounds (5-7), was evaluated. Generally, osteocalcin promoter transactivation activity decreased in the order of C24-fluoro, C23-fluoro, and C22-fluoro analogues. In addition, the metabolic stability of C22-fluoro-25-hydroxyvitamin D3 (5-7) against hCYP24A1 metabolism was also evaluated. 22,22-Difluoro-25(OH)D3 (7) was more stable against hCYP24A1 metabolism compared with its non-fluorinated counterpart 25-hydroxyvitamin D3 (1), but fluorination at the C22 position had little effect on the metabolic stability compared with C24- and C23-fluoro analogues. Our research clarified that side-chain fluorination in vitamin D markedly changes CYP24A1 metabolic stability depending on the fluorinating position.
ABSTRACT
As an extension of our research on providing a chemical library of side-chain fluorinated vitamin D3 analogues, we newly designed and synthesized 26,27-difluoro-25-hydroxyvitamin D3 (1) and 26,26,27,27-tetrafluoro-25-hydroxyvitamin D3 (2) using a convergent method applying the Wittig-Horner coupling reaction between CD-ring ketones (13, 14) and A-ring phosphine oxide (5). The basic biological activities of analogues, 1, 2, and 26,26,26,27,27,27-hexafluoro-25-hydroxyvitamin D3 [HF-25(OH)D3] were examined. Although the tetrafluorinated new compound 2 exhibited higher binding affinity for vitamin D receptor (VDR) and resistance to CYP24A1-dependent metabolism compared with the difluorinated 1 and its non-fluorinated counterpart 25-hydroxyvitamin D3 [25(OH)D3], HF-25(OH)D3 showed the highest activity among these compounds. Osteocalcin promoter transactivation activity of these fluorinated analogues was tested, and it decreased in the order of HF-25(OH)D3, 2, 1, and 25(OH)D3 in which HF-25(OH)D3 showed 19-times greater activity than the natural 25(OH)D3.
Subject(s)
Calcifediol , Calcitriol , Calcitriol/pharmacology , Calcitriol/metabolism , Fluorine , Half-Life , Receptors, Calcitriol/metabolism , Vitamin D3 24-Hydroxylase/metabolismABSTRACT
Our research regarding side-chain fluorinated vitamin D3 analogues has explored a series of efficient fluorination methods. In this study, a new electrophilic stereo-selective fluorination methodology at C24 and C22 positions of the vitamin D3 side-chain was developed using N-fluorobenzenesulfonimide (NFSI) and CD-ring imides with an Evans chiral auxiliary (26,27,30).
Subject(s)
Cholecalciferol , Halogenation , ImidesABSTRACT
In this paper, we report an efficient synthetic route for the 23,23-difluoro-25-hydroxyvitamin D3 (5) and its 24-hydroxylated analogues (7,8), which are candidates for the CYP24A1 main metabolites of 5. The key fragments, 23,23-difluoro-CD-ring precursors (9-11), were synthesized starting from Inhoffen-Lythgoe diol (12), and introduction of the C23 difluoro unit to α-ketoester (19) was achieved using N,N-diethylaminosulfur trifluoride (DAST). Preliminary biological evaluation revealed that 23,23-F2-25(OH)D3 (5) showed approximately eight times higher resistance to CYP24A1 metabolism and 12 times lower VDR-binding affinity than its nonfluorinated counterpart 25(OH)D3 (1).
Subject(s)
Calcifediol , Calcitriol , Calcifediol/metabolism , Calcitriol/pharmacology , Receptors, Calcitriol/metabolism , Vitamin D/analogs & derivatives , Vitamin D3 24-Hydroxylase/metabolismABSTRACT
Lactone-vitamin D3 is a major metabolite of vitamin D3, a lipophilic vitamin biosynthesized in numerous life forms by sunlight exposure. Although lactone-vitamin D3 was discovered 40 years ago, its biological role remains largely unknown. Chemical biological analysis of its photoaffinity probe identified the hydroxyacyl-CoA dehydrogenase trifunctional multienzyme complex subunit alpha (HADHA), a mitochondrial enzyme that catalyzes ß-oxidation of long-chain fatty acids, as its selective binding protein. Intriguingly, the interaction of lactone-vitamin D3 with HADHA does not affect the HADHA enzymatic activity but instead limits biosynthesis of carnitine, an endogenous metabolite required for the transport of fatty acids into the mitochondria for ß-oxidation. Lactone-vitamin D3 dissociates the protein-protein interaction of HADHA with trimethyllysine dioxygenase (TMLD), thereby impairing the TMLD enzyme activity essential in carnitine biosynthesis. These findings suggest a heretofore undescribed role of lactone-vitamin D3 in lipid ß-oxidation and carnitine biosynthesis, and possibly in sunlight-dependent shifts of lipid metabolism in animals.
Subject(s)
Lipid Metabolism , Vitamin D , Animals , Carnitine , Cholecalciferol , Fatty Acids/metabolism , Lactones , Oxidation-Reduction , VitaminsABSTRACT
Two 24-fluoro-25-hydroxyvitamin D3 analogues (3,4) were synthesized in a convergent manner. The introduction of a stereocenter to the vitamin D3 side-chain C24 position was achieved via Sharpless dihydroxylation, and a deoxyfluorination reaction was utilized for the fluorination step. Comparison between (24R)- and (24S)-24-fluoro-25-hydroxyvitamin D3 revealed that the C24-R-configuration isomer 4 was more resistant to CYP24A1-dependent metabolism than its 24S-isomer 3. The new synthetic route of the CYP24A1 main metabolite (24R)-24,25-dihydroxyvitamin D3 (6) and its 24S-isomer (5) was also studied using synthetic intermediates (30,31) in parallel.
Subject(s)
Calcifediol/analogs & derivatives , Fluorides/chemical synthesis , Vitamin D3 24-Hydroxylase/metabolism , Drug Stability , Fluorides/chemistry , Humans , Molecular Structure , StereoisomerismABSTRACT
The vitamin D3 structure consists of the A-ring, a linker originating from the B-ring, C-ring, D-ring, and side-chain moieties. Each unit has its unique role in expressing the biological activities of vitamin D3. Many efforts have been made to date to assess the possible clinical use of vitamin D. Some organic chemists focused on the D-ring structure of vitamin D and synthesized D-ring-modified vitamin D analogues, and their biological activities were studied. This review summarizes the synthetic methodologies of D-ring-modified vitamin D analogues, except for seco-D, and their preliminary biological profiles.
Subject(s)
Vitamin D/analogs & derivatives , Vitamin D/chemical synthesis , Animals , Cholecalciferol/chemistry , Humans , Naphthalenes/chemistry , Vitamin D/chemistry , Vitamin D/pharmacologyABSTRACT
The discovery of a large variety of functions of vitamin D3 and its metabolites has led to the design and synthesis of a vast amount of vitamin D3 analogues in order to increase the potency and reduce toxicity. The introduction of highly electronegative fluorine atom(s) into vitamin D3 skeletons alters their physical and chemical properties. To date, many fluorinated vitamin D3 analogues have been designed and synthesized. This review summarizes the molecular structures of fluoro-containing vitamin D3 analogues and their synthetic methodologies.
Subject(s)
Fluorine Compounds/chemical synthesis , Vitamin D/analogs & derivatives , Vitamin D/chemical synthesisABSTRACT
Vitamin D3 metabolites inhibit the expression of lipogenic genes by impairing sterol regulatory element-binding protein (SREBP), a master transcription factor of lipogenesis, independent of their canonical activity through a vitamin D receptor (VDR). Herein, we designed and synthesized a series of vitamin D derivatives to search for a drug-like small molecule that suppresses the SREBP-induced lipogenesis without affecting the VDR-controlled calcium homeostasis in vivo. Evaluation of the derivatives in cultured cells and mice led to the discovery of VDR-silent SREBP inhibitors and to the development of KK-052 (50), the first vitamin D-based SREBP inhibitor that has been demonstrated to mitigate hepatic lipid accumulation without calcemic action in mice. KK-052 maintained the ability of 25-hydroxyvitamin D3 to induce the degradation of SREBP but lacked in the VDR-mediated activity. KK-052 serves as a valuable compound for interrogating SREBP/SCAP in vivo and may represent an unprecedented translational opportunity of synthetic vitamin D analogues.
Subject(s)
Drug Design , Sterol Regulatory Element Binding Proteins/metabolism , Vitamin D/analogs & derivatives , Animals , Body Weight/drug effects , CHO Cells , Cricetinae , Cricetulus , Cycloaddition Reaction , Disease Models, Animal , Drug Evaluation, Preclinical , Fatty Liver/drug therapy , Humans , Intracellular Signaling Peptides and Proteins/antagonists & inhibitors , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Lipogenesis/drug effects , Membrane Proteins/antagonists & inhibitors , Membrane Proteins/genetics , Membrane Proteins/metabolism , Mice , Mice, Inbred C57BL , Mice, Obese , Receptors, Calcitriol/antagonists & inhibitors , Receptors, Calcitriol/metabolism , Sterol Regulatory Element Binding Proteins/antagonists & inhibitors , Sterol Regulatory Element Binding Proteins/genetics , Vitamin D/metabolism , Vitamin D/pharmacology , Vitamin D/therapeutic useABSTRACT
During our ongoing studies of vitamin D, we focused on the vitamin D3 side-chain 24-position, which is the major metabolic site of human CYP24A1. In order to inhibit the metabolism of vitamin D3, 24,24-difluorovitamin D3analogues are important candidates. In this paper, we report the practical introduction of the difluoro-unit to the 24-position to synthesize 24,24-difluoro-CD ring (1) and 24,24-difluoro-25-hydroxyvitamin D3 (2).
Subject(s)
Calcitriol/analogs & derivatives , Fluorine/chemistry , Vitamins/chemistry , Calcitriol/chemistryABSTRACT
Two novel 23-fluorinated 25-hydroxyvitamin D3 analogues were synthesized using Inhoffen-Lythgoe diol as a precursor of the CD-ring, efficiently. Introduction of the C23 fluoro group was achieved by the deoxy-fluorination reaction using N,N-diethylaminosulfur trifluoride or 2-pyridinesulfonyl fluoride (PyFluor). Kinetic studies on the CYP24A1-dependent metabolism of these two analogues revealed that (23S)-23-fluoro-25-hydroxyvitamin D3 was more resistant to CYP24A1-dependent metabolism than its 23R isomer.
