Synthesis and characterization of 20-hydroxyvitamin D3 with the A-ring modification

Two novel 20-hydroxyvitamin D₃ analogues (4a,b) with the A-ring modification have been synthesized by a convergent manner. An alternative pathway of vitamin D₃ metabolism by cytochrome P450scc CYP11A1 was reported to afford 20-hydroxyvitamin D₃ (3), functions of which remain to be explored. Based on the structure of the 20-hydroxy metabolite, novel analogues (4a,b) with the modifications, including the 1α-hydroxy, 25-hydroxy and 2α-methyl groups, have been designed. The side chain of the requisite CD-ring portions (9a,b) was introduced by Grignard reaction as a key step, and the stereochemistry at the C20 position was confirmed by the X-ray crystal structure analysis of the synthetic intermediate (8b). Preliminary biological characterization using the bovine thymus vitamin D receptor suggested that the introduction of the active motifs into the 20-hydroxyvitamin D₃ scaffold elevated the receptor affinity.

Synthetic strategy and biological activity of A-ring stereoisomers of 1,25- dihydroxyvitamin D3 and C2-modified analogues

The hormonally active form of vitamin D3, 1α,25-dihydroxyvitamin D3 (1a), has a wide variety of biological activities and its major molecular target is considered to be the vitamin D receptor (VDR). The A-ring stereoisomers of 1a as well as its C2-modified analogues, which have different stereochemistry at the C1 and/or C3 hydroxy groups, are of interest since recent metabolic studies have shown that catabolism could occur through A-ring modification. In this review, a practical and versatile synthesis of the A-ring enyne precursors by the convergent method of Trost and coworkers, which is needed to construct all possible A-ring stereoisomers of 1,25-dihydroxyvitamin D3 (1a-d), and the C2-modified analogues (4a-d, 5a-d, 6a-d and 7a-d) is described. A strategy for the synthesis and evaluation of all possible A-ring stereoisomers of 1a and their A-ring modified analogues is important, and this will stimulate synthesis and biological studies into vitamin D.

Novel vitamin D receptor ligands having a carboxyl group as an anchor to arginine 274 in the ligand-binding domain

Vitamin D3 is metabolized into the hormonally active form, 1alpha,25-dihydroxyvitamin D3 (1), via 25-hydroxyvitamin D3 (2) which is the most abundant circulating metabolite. Introduction of the 1alpha-hydroxyl group into 25-hydroxyvitamin D3 (2) to produce 1alpha,25-dihydroxyvitamin D3 (1) increases the VDR binding affinity by approximately 1000-fold. The X-ray crystal structure of human VDR in complex with 1alpha,25-dihydroxyvitamin D3 (1) shows that, together with Ser-237, the 1alpha-hydroxyl group of 1alpha,25-dihydroxyvitamin D3 (1) makes hydrogen bonds with Arg-274, single mutation of which results in impaired ligand recognition. In 2002, lithocholic acid, which possesses a carboxyl group at position C24, was demonstrated to be a weak VDR ligand. We speculated that the carboxylic acid of lithocholic acid could be recognized by Arg-274 in the ligand-binding domain of VDR. In view of the significance of Arg-274 to direct the 1alpha-hydroxyl group, as well as the results with lithocholic acid and its derivatives, we designed the C2 modified analogues of 25-hydroxylvitamin D3 (2) having a carboxyl group, instead of the 1-hydroxyl group, for better electrostatic interaction to the guanidinium side-chain of arginine.

Light propagation from a fluorescent particle embedded in a photonic cluster of micrometer-sized dielectric spheres

In self-assembled multilayer arrays of micrometer-sized spheres that include small amounts of fluorescent particles, unique six-dot-triangular and seven-dot-hexagonal patterns have been known to appear in the fluorescence microscopic images. Although it has been suggested that these two types of patterns correspond to local domain structures, i.e., face centered cubic (fcc) or hexagonal closed packed (hcp), no conclusive evidence has been provided to support this claim. In this study, we systematically investigated the relationship between the propagation patterns and the arrangement of the particles. Through a cross-check between an experiment using well-defined clusters fabricated by a micromanipulation technique and a rigorous calculation based on the expansion of vector spherical harmonics, we confirmed that the six-dot-triangular and seven-dot-hexagonal patterns correspond to the fcc and hcp domains, respectively. Further, we also found that the propagation patterns depend on the size of the clusters. As a result of a quantitative discussion on the light propagation in clusters with various sizes, it was clarified that a sufficient domain size is necessary for the appearance of clear triangular or hexagonal patterns.

[Traumatic diaphragmatic hernia presenting with shock 1 year after blunt injury; report of a case]

A 62-year-old male who had had the left femoral neck fracture due to a traffic accident 1 year earlier was admitted to our hospital because of abdominal pain. He was diagnosed with a left traumatic diaphragmatic hernia due to the previous traffic accident; his condition was also complicated by shock because the mediastinum was compressed by his severely dilated stomach. We performed an emergent operation. A thoracotomy revealed a large defect, about 5 cm in size, at the central tendon of the left diaphragm and a severely dilated stomach in the left thoracic cavity. The ruptured diaphragm was closed directly after reduction of the stomach.

Probing a water channel near the A-ring of receptor-bound 1 alpha,25-dihydroxyvitamin D3 with selected 2 alpha-substituted analogues

The crystal structure of the vitamin D receptor (VDR) in complex with 1 alpha,25(OH)2D3 revealed the presence of several water molecules near the A-ring linking the ligand C-2 position to the protein surface. Here, we report the crystal structures of the human VDR ligand binding domain bound to selected C-2 alpha substituted analogues, namely, methyl, propyl, propoxy, hydroxypropyl, and hydroxypropoxy. These specific replacements do not modify the structure of the protein or the ligand, but with the exception of the methyl substituent, all analogues affect the presence and/or the location of the above water molecules. The integrity of the channel interactions and specific C-2 alpha analogue directed additional interactions correlate with the binding affinity of the ligands. In contrast, the resulting loss or gain of H-bonds does not reflect the magnitude of HL60 cell differentiation. Our overall findings highlight a rational approach to the design of more potent ligands by building in features revealed in the crystal structures.

Methyl-introduced A-ring analogues of 1alpha,25-dihydroxyvitamin D3: synthesis and biological evaluation

The hormonally-active metabolite of vitamin D, 1alpha,25-dihydroxyvitamin D3 (1), has a wide variety of biological activities, which makes it a promising therapeutic agent for the treatment of cancer, psoriasis and osteoporosis. Insights into the structure-activity relationships of the A-ring of 1 are needed to assist the development of more potent and selective analogues, as well as to define the molecular mode of action. All possible A-ring stereoisomers of 2-methyl-1,25-dihydroxyvitamin D3 and 2,2-dimethyl-1,25-dihydroxyvitamin D3, which differ in stereochemistry at the C1-, C2- and C3-positions, were designed and efficiently synthesized by employing the convergent method. Biological evaluation of the analogues, in terms of the vitamin D receptor-binding affinity and HL-60 cell differentiation-inducing activity, as well as the transcriptional potency in ROS 17/2.8 cells, revealed the importance of substituents at the C2-position in certain orientations.

The antagonism between 2-methyl-1,25-dihydroxyvitamin D3 and 2-methyl-20-epi-1,25-dihydroxyvitamin D3 in non-genomic pathway-mediated biological responses induced by 1alpha,25-dihydroxyvitamin D3 assessed by NB4 cell differentiation

We synthesized all eight possible A-ring diastereomers of 2-methyl substituted analogs of 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3] and also all eight A-ring diastereomers of 2-methyl-20-epi-1alpha,25(OH)2D3. Their biological activities, especially the antagonistic effect on non-genomic pathway-mediated responses induced by 1alpha,25(OH)2D3 or its 6-s-cis-conformer analog, 1alpha,25(OH)2-lumisterol3, were assessed using an NB4 cell differentiation system. Antagonistic activity was observed for the 1beta-hydroxyl diastereomers, including 2beta-methyl-1beta,25(OH)2D3 and 2beta-methyl-3-epi-1beta,25(OH)2D3. Very interestingly, 2beta-methyl-3-epi-1alpha,25(OH)2D3 also antagonized the non-genomic pathway, despite its 1alpha-hydroxyl group. Other 1alpha-hydroxyl diastereomers did not show antagonistic activity. 20-epimerization diminished the antagonistic effect of all of these analogs on the non-genomic pathway. These findings suggested that the combination of the 2-methyl substitution of the A-ring and 20-epimerization of the side chain could alter the biological activities in terms of antagonism of non-genomic pathway-mediated biological response. Based on a previous report, 2-methyl substitution alters the equilibrium of the A-ring conformation between the alpha- and beta-chair conformers. The 2beta-methyl diastereomers, which exhibited antagonism on non-genomic pathway-mediated response, were considered to prefer the beta-conformer. Further examination to elucidate the relationship between the altered ligand shape and receptors interaction will be important for molecular level understanding of the mechanism of antagonism of the non-genomic pathway.

METABOLISM OF 2α-PROPOXY-1α,25-DIHYDROXYVITAMIN D3AND 2α-(3-HYDROXYPROPOXY)-1α,25-DIHYDROXYVITAMIN D3BY HUMAN CYP27A1 AND CYP24A1

Recently, we demonstrated that some A-ring-modified vitamin D3 analogs had unique biological activity. Of these analogs, 2alpha-propoxy-1alpha,25(OH)2D3 (C3O1) and 2alpha-(3-hydroxypropoxy)-1alpha,25(OH)2D3 (O2C3) were examined for metabolism by CYP27A1 and CYP24A1. Surprisingly, CYP27A1 catalyzed the conversion from C3O1 to O2C3, which has 3 times more affinity for vitamin D receptor than C3O1. Thus, the conversion from C3O1 to O2C3 by CYP27A1 is considered to be a metabolic activation process. Five metabolites were detected in the metabolism of C3O1 and O2C3 by human CYP24A1 including both C-23 and C-24 oxidation pathways. On the other hand, three metabolites of the C-24 oxidation pathway were detected in their metabolism by rat CYP24A1, indicating a species-based difference in the CYP24A1-dependent metabolism of C3O1 and O2C3 between humans and rats. Kinetic analysis revealed that the Km and kcat values of human CYP24A1 for O2C3 are, respectively, approximately 16 times more and 3 times less than those for 1alpha,25(OH)2D3. Thus, the catalytic efficiency, kcat/Km, of human CYP24A1 for O2C3 is only 2% of 1alpha,25(OH)2D3. These results and a high calcium effect of C3O1 and O2C3 in animal experiments using rats suggest that C3O1 and O2C3 are promising for clinical treatment of osteoporosis.

Proposal of a new prognostic model for hepatocellular carcinoma: an analysis of 403 patients

BACKGROUND

The prognosis of hepatocellular carcinoma (HCC) is highly dependent on tumour extension and liver function. Recently, two new prognostic scoring systems-the CLIP score, developed by Italian investigators and the BCLC score, developed in Barcelona-have been widely used to assess prognosis in patients presenting with hepatocellular carcinoma. Each system has its own relative limitations.

AIMS

To create a new prognostic scoring system which is simple, easy to calculate, and suitable for estimating prognosis during radical treatment of early HCC.

METHODS

A total of 403 consecutive patients with HCC treated by percutaneous ablation at the Department of Gastroenterology, University of Tokyo Hospital, between 1990 and 1997 were used as the training sample to identify prognostic factors for our patients and used to develop the Tokyo score. As a testing sample, 203 independent patients who underwent hepatectomy at the Department of Hepato-Biliary-Pancreatic Surgery were studied. Prognostic factors were analysed by univariate and multivariate Cox proportional hazard regression.

RESULTS

The Tokyo score consists of four factors: serum albumin, bilirubin, and size and number of tumours. Five year survival was 78.7%, 62.1%, 40.0%, 27.7%, and 14.3% for Tokyo scores 0, 1, 2, 3, and 4-6, respectively. The discriminatory ability of the Tokyo score was internally validated by bootstrap methods. The Tokyo score, CLIP score, and BCLC staging were compared by Akaike information criterion and Harrell's c index among training and testing samples. In the testing sample, the predictive ability of the Tokyo score was equal to CLIP and better than BCLC staging.

CONCLUSIONS

The Tokyo score is a simple system which provides good prediction of prognosis for Japanese patients with HCC requiring radical therapy.

Design and Efficient Synthesis of 2α-(ω-Hydroxyalkoxy)-1α,25-dihydroxyvitamin D3 Analogues, Including 2-epi-ED-71 and Their 20-Epimers with HL-60 Cell Differentiation Activity

A concise and efficient synthetic approach to 2 alpha-(omega-hydroxyalkoxy)-1 alpha,25-dihydroxyvitamin D(3) (4a-c), including 2-epi-ED-71, was developed starting from D-glucose as a chiral template for the construction of the 2 alpha-modified A-ring precursors (11a-c). It was found that the best ligand for the bovine thymus vitamin D receptor (VDR) in this series is 4b, which has 1.8 times greater binding affinity for the bovine thymus VDR than that of the natural hormone 1. Interestingly, potency in the induction of HL-60 cell differentiation for 4a-c was almost the same or weaker than that of 1 despite the strong binding affinity for the VDR. Next, we were interested in the "double modification"of 1 based on 4a-c with C20-epimerization, affording 2 alpha-(omega-hydroxyalkoxy)-20-epi-1 alpha,25-dihydroxyvitamin D(3) (20-epi-4a-c). All three 2 alpha-substituted 20-epi analogues of 1 (20-epi-4a-c) exhibited stronger binding affinities for the VDR, and their conformations in the ligand binding domain of VDR were analyzed by molecular modeling. Double-modified analogues of 20-epi-4a-c showed marked HL-60 cell differentiation activity, and 20-epi-4a possesses an activity 58-fold higher than that of the natural hormone 1.

Metabolism of A-ring diastereomers of 1α,25-dihydroxyvitamin D3 by CYP24A1

The metabolism of 1alpha,25(OH)(2)D(3) (1alpha,3beta) and its A-ring diastereomers, 1beta,25(OH)(2)D(3) (1beta,3beta), 1alpha,25(OH)(2)-3-epi-D(3) (1alpha,3alpha), and 1beta,25(OH)(2)-3-epi-D(3) (1beta,3alpha), was examined to compare the substrate specificity and reaction specificity of CYP24A1 between humans and rats. The ratio between C-23 and C-24 oxidation pathways in human CYP24A1-dependent metabolism of (1alpha,3alpha) and (1beta,3alpha) was 1:1, although the ratio for (1alpha,3beta) and (1beta,3beta) was 1:4. These results indicate that the orientation of the hydroxyl group at the C-3 position determines the ratio between C-23 and C-24 oxidation pathways. A remarkable increase of metabolites in the C-23 oxidation pathway was also observed in rat CYP24A1-dependent metabolism. The binding affinity of human CYP24A1 for A-ring diastereomers was (1alpha,3beta)>(1alpha,3alpha)>(1beta,3beta)>(1beta,3alpha), indicating that both hydroxyl groups at C-1 and C-3 positions significantly affect substrate-binding. The information obtained in this study is quite useful for understanding substrate recognition of CYP24A1 and designing new vitamin D analogs.

FT-Raman spectroscopy of calcium hydroxide medicament in root canals

AIM

To investigate chemical changes in calcium hydroxide introduced into human root canals as a medicament using Fourier transform-(FT) Raman spectroscopy.

METHODOLOGY

Ten necrotic maxillary anterior teeth were selected in 10 patients. The teeth were divided into five treatment groups, according to the survey time. Root canal instrumentation was performed with hand instruments until the master apical file was size 40. Calcium hydroxide paste, in a 1 : 1.25 mixture by weight of powder and distilled water, was introduced directly into the root canal with a lentulo-spiral filler and then condensed with a finger plugger. The access cavity was sealed with a temporary dressing. After 2 and 4 days, then 2, 4 and 6 weeks, the calcium hydroxide paste was sampled with a K-file and then analysed using FT-Raman spectroscopy. The excitation source was an Nd : YAG laser with an excitation wavelength of 1064 nm. All spectra were taken with a laser power of 200 mW, 275-1185 scans, and 4 cm(-1) resolution. The conversion of calcium hydroxide to calcium carbonate was calculated on the basis of the spectral data obtained from the mixtures of both compounds.

RESULTS

The calcium hydroxide paste in the apical region showed weak bands at 1088 and 284 cm(-1), in addition to bands associated with calcium hydroxide. The weak bands, assigned to calcium carbonate, became stronger with time. Calcium carbonate content increased rapidly in the first 2 days and then tended to increase slowly. Approximately 11% of the calcium hydroxide at the apical portion of the canal was converted to calcium carbonate after 6 weeks. However, little alteration of the paste was noticed in the samples from the middle portion of the canal.

CONCLUSIONS

Calcium hydroxide medicament in root canals became transformed into calcium carbonate in the apical region within 2 days. Although the transformation continued with time, approximately 90% of the calcium hydroxide remained unchanged after 6 weeks.

2,2-Functionalized analogues of 1alpha,25-dihydroxyvitamin D3, the potent inducers of cell differentiation

All four possible A-ring stereoisomers of 2,2-dimethyl-1,25-dihydroxyvitamin D(3) (4) were designed and convergently synthesized. Nine-step conversion of methyl hydroxypivalate 6 provided the desired A-ring enyne synthon (13a,b) in good overall yield. Cross-coupling reaction of the A-ring synthon 13a,b with the CD-ring portion in the presence of palladium catalyst, followed by deprotection, gave the vitamin analogues (4a-d). We also synthesized four stereoisomers of 2,2-ethano-1,25-dihydroxyvitamin D(3) (5), as novel spiro-ring analogues having cyclopropane fused at the C2 position. Biological potencies of the synthesized compounds were assessed in terms of the vitamin D receptor (VDR) binding affinity, as well as the HL-60 cell differentiation-inducing activity. The 2,2-ethano analogue 5a showed a comparable activity to the natural hormone 1, while the 2,2-dimethyl analogue 4a exhibited one-third of the activity of 1 in cell differentiation, with the reduced VDR binding affinity.

Design, synthesis, and biological studies of the A-ring-modified 1,25-dihydroxyvitamin D3 analogs

Antitumor effects of 1alpha,25-dihydroxyvitamin D3 analogs have recently become one of the major topics of the vitamin D research field. We focused on the structure-activity relationships of the A-ring moiety of the vitamin D molecule and found several strong agonists of the vitamin D receptor, using a design of introducing a functional group into the C2 position. In the first step, all eight possible diastereomers of novel 2-methyl-1,25-dihydroxyvitamin D3 were synthesized using the convergent method with palladium catalyzed coupling reaction. We studied conformational analysis of each isomer based on 1H NMR and computer calculations; and biologically, VDR binding affinity, potency of induction of HL-60 cell differentiation, and apoptosis were investigated in detail. The biological effect of double modification in a combination of the CD-ring side chain (20-epi, 20-epi-22R-methyl, and KH-1060 types) and the 2-methyl group was then evaluated. In this context, 5,6-trans derivatives of 2-methyl analogs were also synthesized and tested. Through these experiments, our accumulated knowledge that the 2a-methylated analog with the natural la,3fl-dihydroxyl groups possesses a strong and unique biological profile guided us the next synthetic goal, i.e., three kinds of longer functional groups: 2alpha-alkyl, 2alpha-hydroxyalkyl, and 2alpha-hydroxyalkoxyl groups, which were introduced into 1alpha,25-dihydroxyvitamin D3, stereoselectively. We found that five of our new 2alpha-modified analogs show higher VDR-binding affinity than that of the natural hormone. HL-60 cell differentiation induction activities and calcium mobilization were studied for some of these compounds. These are the first examples, including the pioneer 2a-methyl analog, that exhibit higher VDR-binding affinity than 1alpha,25-dihydroxyvitamin D3 with pure A-ring modifications. To explain the effect, docking studies of the synthetic ligands to VDR are also described. This study could stimulate the development of antitumor medicines of the vitamin D analogs.

Dramatic Enhancement of Antagonistic Activity on Vitamin D Receptor: A Double Functionalization of 1α-Hydroxyvitamin D3 26,23-Lactones

The synthesis of novel vitamin D receptor antagonists, 24-methyl-1alpha-hydroxyvitamin D(3) 26,23-lactones, is reported. We found that the biological activities of the vitamin D(3) lactones were affected by the structure of the lactone part. Furthermore, introduction of a 2alpha-methyl group into the 24-methylvitamin D(3) lactones dramatically enhanced their anti-vitamin D activity. [reaction: see text]

Metabolism of 20-epimer of 1α,25-dihydroxyvitamin D3 by CYP24: species-based difference between humans and rats

The 20-epi form of 1alpha,25-dihydroxyvitamin D(3) (1alpha,25(OH)(2)-20-epi-D(3)) is expected as drugs for leukemia, other cancers or psoriasis, because it shows several-hundred fold enhanced ability to induce cell differentiation and growth inhibition than 1alpha,25-dihydroxyvitamin D(3) while its calcemic activity is only slightly elevated. In this study, we compared the human and rat CYP24-dependent metabolism of 1alpha,25(OH)(2)-20-epi-D(3) by using the Escherichia coli expression system. The HPLC and LC-MS analyses of the metabolites revealed that rat CYP24 converted 1alpha,25(OH)(2)-20-epi-D(3) to 25,26,27-trinor-1alpha(OH)-24(COOH)-20-epi-D(3) through 1alpha,24,25(OH)(3)-20-epi-D(3) and 1alpha,25(OH)(2)-24-oxo-20-epi-D(3). The binding affinity of trinor-1alpha(OH)-24(COOH)-20-epi-D(3) for vitamin D receptor (VDR) was less than 1/4000 of that of 1alpha,25(OH)(2)-20-epi-D(3). These results suggest that rat CYP24 can almost completely inactivate 1alpha,25(OH)(2)-20-epi-D(3). On the other hand, human CYP24 mainly converted 1alpha,25(OH)(2)-20-epi-D(3) to its putative demethylated compound with a hydroxyl group, via 1alpha,24,25(OH)(3)-20-epi-D(3), 1alpha,25(OH)(2)-24-oxo-20-epi-D(3), and 1alpha,23,25(OH)(3)-24-oxo-20-epi-D(3). All of these metabolites showed considerable affinity for vitamin D receptor. These results clearly demonstrate the species-based difference between human and rat on the CYP24-dependent metabolism of 1alpha,25(OH)(2)-20-epi-D(3).

Concise synthesis and biological activities of 2α-Alkyl- and 2α-(ω-Hydroxyalkyl)-20- epi -1α,25-dihydroxyvitamin D 3

We found a concise route to the Trost A-ring precursor enyne for synthesizing 2alpha-alkylated 1alpha,25-dihydroxyvitamin D(3) (1) from D-glucose. The enynes were coupled with the 20-epi-CD ring part to study the effect of the double modification of 2alpha-substitution and 20-epimerization upon biological activities of 1. The novel three analogues of 2alpha-alkyl- and four analogues of 2alpha-(omega-hydroxyalkyl)-20-epi-1alpha,25-dihydroxyvitamin D(3) (5b-d and 6a-d) showed higher binding affinity for vitamin D receptor (VDR) and more potent activity in induction of HL-60 cell differentiation than those of the natural hormone 1.

Efficient synthesis of 2-modified 1alpha,25-dihydroxy-19-norvitamin D3 with Julia olefination: high potency in induction of differentiation on HL-60 cells

Six novel 2-substituted analogues of 1alpha,25-dihydroxy-19-norvitamin D(3), 6a,b-8a,b, were efficiently synthesized utilizing (-)-quinic acid as the A-ring precursor. The C2-modified A-rings were prepared as 4-alkylated (3R,5R)-3,5-dihydroxycyclohexanones 12-15 from (-)-quinic acid based on radical allylation at the C4 position of methyl (-)-quinicate. The new type of the CD-ring coupling partner 23 was synthesized from 25-hydroxy Grundmann's ketone 19 to apply to the modified Julia olefination to construct a diene unit between the A-ring and the CD-ring. The coupling yields, including a deprotection step, were 47-62%. After the separation of the diastereomers based on C2 stereochemistry, the structure (2alpha or 2beta) was determined by (1)H NMR experiments and compared to DeLuca's 2-methyl- and 2-ethyl-1alpha,25-dihydroxy-19-norvitamin D(3). Thus, the synthesized 2alpha-(3-hydroxypropyl)-1alpha,25-dihydroxy-19-norvitamin D(3) (8a) showed almost the same potency in binding to the bovine thymus vitamin D receptor (VDR) as the natural hormone 1, while its beta-isomer 8b had only a 3% affinity. Both 2alpha-allyl- and 2alpha-propyl-1alpha,25-dihydroxy-19-norvitamin D(3) (6a and 7a) and their 2beta-analogues (6b and 7b) possessed a weak affinity for the VDR. The strong VDR ligand 8a was ca. 36-fold more potent in induction of HL-60 cell differentiation than 1, and interestingly, even the weaker ligand 8b showed a 6.7-fold higher potency in the cell differentiation activity than that of 1.

Design and synthesis of potent vitamin D receptor antagonists with A-ring modifications: remarkable effects of 2alpha-methyl introduction on antagonistic activity

Novel A-ring analogues of the vitamin D receptor (VDR) antagonist (3a), ZK-159222, and its 24-epimer (3b) were convergently synthesized. Preparation of the CD-ring portions with the side chains of 3a,b, followed by palladium-catalyzed cross-coupling with the A-ring enyne precursors (15a,b), (3S,4S,5R)- and (3S,4S,5S)-bis[(tert-butyldimethylsilyl)oxy]-4-methyloct-1-en-7-yne, afforded the 2alpha-methyl-introduced analogues (4a,b) and their 3-epimers (5a,b). The biological profiles of the hybrid analogues were assessed in terms of affinity for VDR, and antagonistic activity to inhibit HL-60 cell differentiation induced by the natural hormone, 1alpha,25-dihydroxyvitamin D(3). The analogue 4a showed an approximately fivefold higher antagonistic activity compared with 3a. The 2alpha-methyl introduction into 3a increased the receptor affinity, thereby enhancing VDR antagonism. This approach to design potent antagonists based on hybridization of structural motifs in the A-ring and in the side chain may prove to be valuable.

Synthesis of 2,2-dimethyl-1,25-dihydroxyvitamin D3: A-ring structural motif that modulates interactions of vitamin D receptor with transcriptional coactivators

A concise synthesis of all four possible A-ring stereoisomers of 2,2-dimethyl-1,25-dihydroxyvitamin D3 and characterization of their distinct transcriptional features, which appear to have been inherited from the corresponding 2alpha-methyl derivatives, is reported.

A novel support system for patient immobilization and transportation for daily computed tomographic localization of target prior to radiation therapy

PURPOSE

To develop a method for quick and smooth transportation of patients from a computed tomography (CT) table to a linear accelerator (linac) table for confirming tumor center before radiation therapy.

MATERIALS AND METHODS

We developed a system using a subtable for patient immobilization that is transported via a customized stretcher. The patient lies on the subtable and is immobilized by a vacuum cushion and thermoplastic body cast. The subtable stretcher is used to carry the subtable from the CT table to the linac table. During transportation, the subtable is kept flat and shock to the subtable is carefully avoided. Between August 2001 and September 2002, a total of 9 patients with solitary upper lung tumors (superior to carina) were treated using this system.

RESULTS

Intrafractional tumor motion along the x (left-right), y (anterior-posterior), and z axis (superior-inferior) ranged from -2 mm to 2 mm, -2 mm to 2 mm, and -5 mm to 3 mm, respectively. The standard deviation of intrafractional tumor motion along the x, y, and z axis ranged from 0.5 mm to 1.5 mm, 0 mm to 1.7 mm, and 0.6 mm to 3.5 mm, respectively. Interfractional setup errors along the x, y, and z axis ranged from -5 mm to 4 mm, -6 mm to 8 mm, and -6 mm to 6 mm, respectively, and we could reduce interfractional setup errors in the majority of treatment sessions.

CONCLUSIONS

We developed a system that allows patients to be immobilized and transported to verify tumor location on a daily basis. This system is highly useful for reducing setup errors.

Remarkable effect of 2α-modification on the VDR antagonistic activity of 1α-hydroxyvitamin D3-26,23-lactones

Novel 2[small alpha]-methyl-, 2[small alpha]-(3-hydroxypropyl)- and 2[small alpha]-(3-hydroxypropoxy)-substituted 25-dehydro-1[small alpha]-hydroxyvitamin D-26,23-lactone derivatives were efficiently synthesized Reformatsky type allylation and palladium-catalyzed alkenylative cyclization processes, and their biological activities were evaluated. Introducing functional groups into the 2[small alpha]-position of the vitamin D-26,23-lactones resulted in remarkable enhancement of their antagonistic activity on vitamin D receptor (VDR).

Design and efficient synthesis of new stable 1alpha,25-dihydroxy-19-norvitamin D3 analogues containing amide bond

The design and synthesis of new 1alpha,25-dihydroxy-19-norvitamin D(3) analogues 3a-c, which have an amide bond in the molecule instead of the diene, are described. The A-ring moiety was constructed by a (3S,5S)-3,5-dihydroxypiperidine derivative (9, 11, or 13) prepared from D-mannose, and a CD-ring carboxylic acid 16 was synthesized from Grundmann's ketone. Coupling those parts gave desired 3a-c in good yield. This strategy can be applied in combinatorial chemistry; therefore, those compounds would be applicable as useful tools in the development of new drugs.

Synthesis and testing of 2alpha-modified 1alpha,25-dihydroxyvitamin D(3) analogues with a double side chain: marked cell differentiation activity

The 2alpha-methyl-, 2alpha-(3-hydroxypropyl)-, and 2alpha-(3-hydroxypropoxy)-derivatives of the 'double side chain' analogue of 1alpha,25-dihydroxyvitamin D(3) were synthesized using Trost A-ring/CD-ring connective strategy. Regarding the requisite A-ring building blocks, a new, high yield and stereoselective route to the 2alpha-methyl compound starting from D-glucose was developed. All three new analogues showed potent HL-60 cancer cell differentiation activity.

Metabolism of 2-methyl analogs of 1alpha,25-dihydroxyvitamin D3 in rat osteosarcoma cells (UMR 106)

Several novel A-ring modified analogs of 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3] have been synthesized in order to investigate the structure-function relationships of 1alpha,25(OH)2D3. We synthesized A-ring modified analogs which contain a methyl group on C-2 of the A-ring. There are eight 2-methyl diastereomers, which differ in the stereochemistry of the methyl group on C-2 and the hydroxyl groups on C-1 and C-3. Further our biological activity studies of the 2-methyl diastereomers indicated that the potency of each analog is highly dependent on the stereochemistry of the A-ring substituents [Konno et al., Biorg. Med. Chem. Letts. 8(2), 151-156 (1998); Nakagawa et al., Biochem. Pharmacol. 60(12), 1937-1947 (2000)]. For example, the VDR binding affinities exhibited by the 1alpha-isomers are significantly higher than those exhibited by the 1beta-isomers. Furthermore, out of all the 1alpha-isomers, the 2alpha-methyl isomers, when compared to the corresponding 2beta-methyl isomers, showed much higher potency in inducing cell differentiation of HL-60 cells, but failed to stimulate apoptosis. In contrast the 2beta-methyl isomers strongly stimulated apoptosis. At present it is unknown how the addition of the 2-methyl modification to the hormone, 1alpha,25(OH)2D3 alters its metabolism in target tissues. Previously, we reported that 1alpha,25(OH)2D3 is metabolized in rat osteosarcoma (UMR 106) cells via both the C-24 oxidation and the C-3 epimerization pathways. Therefore, we studied the metabolism of the four 1alpha,2-methyl diastereomers in UMR 106 cells. Our results indicated that in UMR 106 cells, all four diastereomers were metabolized into several polar metabolites via the C-24 oxidation pathway. Thus, the presence of the 2-methyl group on the A-ring did not inhibit the metabolism of the analogs via the C-24 oxidation pathway. However, it is significant to note that the 2-methyl group prevented the metabolism of the analogs via the C-3 epimerization pathway. In summary, we report that the 2-methyl group interferes with the action of the enzyme(s) involved in C-3 epimerization, but not with the enzyme 1alpha,25(OH)2D3-24-hydroxylase, which is responsible for C-24 oxidation pathway.

Determination of absolute configuration of 1,3-diols by the modified Mosher's method using their di-MTPA esters

1,3-Diols are frequently involved in biologically important compounds and, therefore, determination of the stereochemistry of these structural elements, in particular those in acyclic systems, has been one of the focuses of attention in natural products chemistry. The modified Mosher's method, commonly used for the determination of the absolute configuration of secondary alcohols, was applied to determine the absolute configuration of 1,3-diols with their di-MTPA esters. Several epimeric pairs of syn- and anti-1,3-diols with known absolute configurations were converted to the corresponding di-MTPA esters and the iDelta;delta values were then calculated. For the acyclic syn-1,3-diols, the iDelta;delta values were systematically arranged as predicted from the basic concept of the modified Mosher's method, demonstrating that the method is valid for these compounds. In contrast, the iDelta;delta values were irregularly arranged for the acyclic anti-1,3-diols and, accordingly, this method is not valid for these cases. These results are complementary to those of the previously reported CD exciton chirality method and, hence, the combined use of the modified Mosher's method and the CD exciton chirality method can determine the absolute configuration of the acyclic 1,3-diols. Also, this method is successfully applicable to cyclic 1,3-diols irrespective of their relative stereochemistry.

Efficient and versatile synthesis of novel 2alpha-substituted 1alpha,25-dihydroxyvitamin D(3) analogues and their docking to vitamin D receptors

Novel 2alpha-substituted 1alpha,25-dihydroxyvitamin D(3) analogues with 2alpha-alkyl and 2alpha-hydroxyalkyl groups were systematically synthesized from D-xylose. Their conformation on binding to the ligand binding domain (LBD) of the vitamin D receptor was analyzed. It has been found that the 2alpha-hydroxypropyl group best fits the cavity of the LBD, and the binding activity is three times higher than that for the natural hormone.

Synthesis and biological evaluation of all A-ring stereoisomers of 5,6-trans-2-methyl-1,25-dihydroxyvitamin D(3) and their 20-epimers: possible binding modes of potent A-ring analogues to vitamin D receptor

BACKGROUND

The secosteroid 1 alpha,25-dihydroxyvitamin D(3) (1) has a wide variety of biological activities, which makes it a promising therapeutic agent for the treatment of cancer, psoriasis and osteoporosis. Insight into the structure-activity relationships of the A-ring of 1 is still needed to assist the development of more potent and selective analogues as candidate chemotherapeutic agents, as well as to define the molecular mode of action.

RESULTS

All possible A-ring stereoisomers of 5,6-trans-2-methyl-1,25-dihydroxyvitamin D(3) (6a-h) and their 20-epimers (7a-h) were designed and efficiently synthesized. The dependence of the affinities for vitamin D receptor (VDR) and vitamin D binding protein (DBP), as well as the HL-60 cell differentiation-inducing activity, upon the stereochemistry of the A-ring and at C20 in the side chain was evaluated.

CONCLUSIONS

The binding affinities and potency of the 5,6-trans and 5,6-cis analogues were enhanced by a 2-methyl substituent in a certain orientation. Molecular docking studies based upon the X-ray crystal structure of VDR suggested that the axial 2-methyl group would be accommodated in a pocket surrounded by hydrophobic amino acid residues in the ligand binding domain, resulting in enhanced interaction.

Tissue specific metabolism of 1alpha,25-dihydroxy-20-epi-vitamin D3 into new metabolites with significant biological activity: studies in rat osteosarcoma cells (UMR 106 and ROS 17/2.8)

In a recent study, we investigated the metabolism of 1alpha,25-dihydroxy-20-epi-vitamin D3 (1alpha,25(OH)2-20-epi-D3), a potent synthetic vitamin D3 analog in the isolated perfused rat kidney and proposed that the enhanced biological activity of 1alpha,25(OH)2-20-epi-D3 is in part due to its metabolism into stable bioactive intermediary metabolites derived via the C-24 oxidation pathway (Siu-Caldera et al. [1999] J. Steroid. Biochem. Mol. Biol. 71:111-121). It is now well established that 1alpha,25(OH)2D3 and its analogs are metabolized in target tissues not only via the C-24 oxidation pathway but also via the C-3 epimerization pathway. As the perfused rat kidney does not express the C-3 epimerization pathway, we could not identify other possible bioactive metabolites of 1alpha,25(OH)2-20-epi-D3 such as 1alpha,25(OH)2-20-epi-3-epi-D3, derived via the C-3 epimerization pathway. Therefore, we studied the metabolism of 1alpha,25(OH)2-20-epi-D3 in rat osteosarcoma cells (UMR 106) which express both the C-24 oxidation and the C-3 epimerization pathways. Our results indicate that 1alpha,25(OH)2-20-epi-D3 is metabolized in UMR 106 cells into several metabolites which included not only the previously known metabolites of the C-24 oxidation pathway but also three new metabolites which were labeled as metabolites X, Y1, and Y2. Metabolite X was unequivocally identified as 1alpha,25(OH)2-20-epi-3-epi-D3. Even though definite structure identification of the metabolites, Y1 and Y2 was not achieved in our present study, we determined that the metabolite Y1 is produced from 1alpha,25(OH)2-20-epi-D3 and the metabolite Y2 is produced from 1alpha,25(OH)2-20-epi-3-epi-D3. We also noted the production of both 1alpha,25(OH)2-20-epi-3-epi-D3 and the two metabolites Y1 and Y2 in different rat osteosarcoma cells (ROS 17/2.8) which express only the C-3 epimerization pathway but not the C-24 oxidation pathway. Furthermore, we investigated the metabolism of 1alpha,25(OH)2-20-epi-D3 in the isolated perfused rat kidney in an earlier study. The results of this study indicated that the rat kidney unlike rat osteosarcoma cells did not produce either 1alpha,25(OH)2-20-epi-3-epi-D3 or the metabolites Y1 and Y2. Thus, it appears that the metabolites Y1 and Y2, like 1alpha,25(OH)2-20-epi-3-epi-D3, are produced only in specific tissues. Preliminary biological activity of each new metabolite is assessed by measuring its ability to generate VDR-mediated gene transcription. 1alpha,25(OH)2-20-epi-3-epi-D3 was found to be almost equipotent to 1alpha,25(OH)2-20-epi-D3 while the metabolites, Y1 and Y2 were found to be less active. The metabolite Y1 when compared to the metabolite Y2 has higher biological activity and its potency is almost equal to 1alpha,25(OH)2D3. In summary, we report for the first time tissue specific metabolism of 1alpha,25(OH)2-20-epi-D3 into several bioactive metabolites which are derived not only via the previously established C-24 oxidation and C-3 epimerization pathways but also via a new pathway. (c) 2001 Wiley-Liss, Inc.

[A case of endobronchial tuberculosis associated with bronchial asthma treated with high doses of inhaled corticosteroid]

A 46-year-old woman had been treated with 1,600-2,000 micrograms/day of beclomethasone dipropionate (BDP) and oral theophylline on the basis of a diagnosis of bronchial asthma in 1993. Eosinophilic pneumonia was diagnosed in June 1999, and she was then treated with 40 mg/day of oral prednisolone (PSL), which was gradually tapered off, and then stopped in October 1999. She was referred to our hospital because acid-fast bacilli were found in the sputum on January 18, 2000. Her chest radiographs and CT scans showed partial atelectasis of the right upper lobe, and fiberoptic bronchoscopy revealed bronchial inflammatory changes and whitish mucosal nodular lesions in the walls of the lower trachea, the right main bronchus and the orifice of the right upper lobe bronchus. She was found to have endobronchial tuberculosis. Anti-tuberculosis treatment with isoniazid, rifampicin, streptomycin and pyrazinamide was started. Serum levels of interferon-gamma were markedly elevated on admission. Asthma symptoms improved for a period of one month after the beginning of anti-tuberculosis treatment, despite the termination of inhaled corticosteroid. However, as the tuberculosis improved, the frequency and severity of the asthma increased and so corticosteroid inhalation was started again. Four months after administration of the anti-tuberculosis drug, fiberoptic bronchoscopy revealed that the endobronchial lesions had improved without any stenosis or constrictive changes. It was speculated that high doses of inhaled corticosteroid may have the potential to cause endobronchial tuberculosis whilst, ironically, at the same time preventing bronchial stenosis by endobronchial tuberculosis. This is an interesting case in which the asthma symptoms first decreased during the acute phase of endobronchial tuberculosis and then increased again after the tuberculosis improved.

Churg-Strauss syndrome after reduction of inhaled corticosteroid in a patient treated with pranlukast for asthma

Recently, various forms of Churg-Strauss syndrome (CSS) have been reported in association with the use of leukotriene receptor antagonists. A 53-year-old woman with a 5-year history of asthma associated with chronic sinusitis presented mononeuropathy, hypereosinophilia, and positive P-ANCA in October 1999. She had been treated with pranlukast (450 mg/day) and beclomethasone dipropionate (BDP) at a dose of 1,200 microg/day which had gradually been tapered to 800 microg/day over the previous 17 months. She was found to have CSS, and 60 mg/day of prednisolone was administered instead of pranlukast, resulting in an improvement of her symptoms and eosinophilia. Later, we confirmed that serum P-ANCA had been positive before the pranlukast treatment, but CSS vasculitis had not appeared at that time. We speculated that an underlying incomplete form of CSS was being masked in this case and that the reduction of inhaled corticosteroid might have been responsible for the unmasking of CSS.

Hepatocellular carcinoma depicted as hypoattenuation on CT hepatic arteriography (CTA) and hyperattenuation on CT during arterial portography (CTAP)

We report a 68-year-old man with three nodules of hepatocellular carcinoma (HCC) in a cirrhotic liver; the largest nodule was 3.0cm in diameter. The nodules showed hypoattenuation on computed tomography (CT) hepatic arteriography (CTA) and hyperattenuation on CT during arterial portography (CTAP), indicating that the dominant vascularity of the HCC nodules may have been the portal vein. A biopsy specimen obtained from the nodules showed well differentiated HCC (Edmondson-Steiner grade I). The imaging findings of the nodules on both CTA and CTAP are unusual, in spite of the rather large size, so this seemed suggestive of the hemodynamic properties of relatively large nodules of well differentiated HCC.

Systematic studies on synthesis, structural elucidation, and biological evaluation of A-ring diastereomers of 2-methyl-1alpha,25-dihydroxyvitamin D(3) and 20-epi-2-methyl-1alpha,25-dihydroxyvitamin D(3)

All possible A-ring diastereomers of 2-methyl-1alpha,25-dihydroxyvitamin D(3) (2) and 20-epi-2-methyl-1alpha,25-dihydroxyvitamin D(3) (3) were synthesized by palladium-catalyzed coupling reaction of A-ring 'enyne' synthons with CD-ring portions. The A-ring synthons were rationally synthesized via a novel and practical route, starting with methyl (R)-(+)- and (S)-(-)-3-hydroxy-2-methyl-propionate, in good yields. X-ray crystallographic analysis of 2alpha-methyl-1alpha,25-dihydroxyvitamin D(3) (2b) and conformational analysis of the A-ring of 2alpha-methyl-(2b) and 2beta-methyl-1alpha,25-dihydroxyvitamin D(3) (2f) were carried out, and the results are described. All A-ring diastereomers (2 and 3), thus synthesized, were biologically evaluated both in vitro and in vivo. The biologic potency was highly dependent on the stereochemistry of the A-ring substituents. In particular, 2b showed 4-fold higher vitamin D receptor [VDR] binding activity than the natural hormone, and its 20-epimer (3b) exhibited exceptionally high activity, 12-fold more potent in VDR binding, 7-fold in calcium mobilization, and 590-fold in induction of human promyelocytic leukemia (HL-60) cell differentiation as compared with the natural hormone. Further, the 20-epi-2beta-Me-1beta, 3alpha(OH)(2) isomer (3g) had significant biologic potencies compared to the natural hormone despite having 1beta-OH configuration. The transcriptional activities on human osteocalcin gene promoter, including VDRE in transfected mammalian cells, were also evaluated. Finally, there was a clear contrast between the effects of the 2-methyl group on the HL-60 cell differentiation- and apoptosis-inducing activities of 2 and 3.

Diagnostic significance of surfactant proteins A and D in sera from patients with radiation pneumonitis

Radiation pneumonitis (RP) is the most common complication of radiotherapy for thoracic tumours. The aim of this study was to evaluate the significance of pulmonary surfactant proteins (SP)-A and SP-D as new serum markers for RP. Twenty-five patients with lung tumour, who had received radiotherapy, were studied. At the completion of radiotherapy, the presence of RP was judged by chest plain radiography and chest high resolution computed tomography (HRCT). RP findings detected on chest plain radiography were seen in only three of 12 patients in whom RP was detected by HRCT. Nevertheless, both SP-A and SP-D concentrations in sera from the patients with RP were significantly higher than those from the 13 patients without RP (p = 0.0065, p = 0.0011, respectively). As with SP-A, ratios of SP-D at the completion, compared to at the initiation (1 week post/pre ratio), were also significantly higher in patients with RP than in patients without RP. When a post/pre ratio > 1.6 was considered positive, the SP-A and SP-D assays showed an 83% and 85% specificity, respectively. In conclusion, serum assays of surfactant proteins A and D may be of diagnostic value for detection of radiation pneumonitis, even when the radiographic change is faint.

Highly potent cell differentiation-inducing analogues of 1alpha,25-dihydroxyvitamin D3: synthesis and biological activity of 2-methyl-1,25-dihydroxyvitamin D3 with side-chain modifications

Eight 2-methyl substituted analogues of 20-epi-22R-methyl-1alpha,25-dihydroxyvitamin D3 (5) and 20-epi-24,26,27-trihomo-22-oxa-1alpha,25-dihydroxyvitamin D3 (6: KH-1060) were convergently synthesized. Preparation of the CD-ring portions with modified side chains of 5 and 6, followed by palladium-catalyzed cross-coupling with the A-ring enyne synthons (20a-d), (3S,4S,5R)-, (3S,4R,5R)-, (3S,4S,5S)- and (3R,4R,5S)-3,5-bis[(tert-butyldimethylsilyl)oxy]-4-methyloct-1-en-7-yne, afforded two sets of four A-ring stereoisomers of 20-epi-2,22-dimethyl-1,25-dihydroxyvitamin D3 (7a-d) and 20-epi-24,26,27-trihomo-2-methyl-22-oxa-1,25-dihydroxyvitamin D3 (8a-d). The biological profiles of the hybrid analogues were assessed in terms of affinity for vitamin D receptor (VDR) and HL-60 cell differentiation-inducing activity in comparison with the natural hormone. The combined modifications of the A-ring at the 2-position and the side chain yielded analogues with high potency.

Structure-specific control of differentiation and apoptosis of human promyelocytic leukemia (HL-60) cells by A-ring diastereomers of 2-methyl-1alpha,25-dihydroxyvitamin D(3) and its 20-epimer

1alpha,25-dihydroxyvitamin D(3) (1alpha,25(OH)(2)D(3)) has been shown to modulate not only proliferation and differentiation but also apoptosis of malignant cells, indicating that it would be useful for the treatment of hyperproliferative diseases such as cancer and psoriasis. Little information is available concerning structural motifs of the 1alpha,25(OH)(2)D(3) molecule responsible for modulation of differentiation and apoptosis. We synthesized all possible A-ring diastereomers of the 2-methyl-1alpha,25(OH)(2)D(3) and its 20-epimer and evaluated their biological activities in human promyelocytic leukemia (HL-60) cells. Surprisingly, the potent analogues could be clearly divided into two groups: (i) those bearing the 1alpha- and 3beta-hydroxyl groups on the A-ring were potent inducers of differentiation and growth inhibitors of HL-60 cells and (ii) those bearing the 1beta-hydroxyl group together with either 3alpha- or 3beta-hydroxyl groups on the A-ring were potent stimulators of apoptosis in these cells. We have clearly identified for the first time the structural motifs on the basis of the stereochemistry of both hydroxyl groups at positions 1 and 3 of the A-ring of the 1alpha,25(OH)(2)D(3) molecule responsible for the induction of differentiation and apoptosis of HL-60 cells. These findings provide useful information not only for structure-function studies of 1alpha,25(OH)(2)D(3) analogues but also for the development of therapeutic agents for the treatment of leukemia and other cancers.

Synthesis, biological evaluation, and conformational analysis of A-ring diastereomers of 2-methyl-1,25-dihydroxyvitamin D(3) and their 20-epimers: unique activity profiles depending on the stereochemistry of the A-ring and at C-20

All eight possible A-ring diastereomers of 2-methyl-1, 25-dihydroxyvitamin D(3) (2) and 2-methyl-20-epi-1, 25-dihydroxyvitamin D(3) (3) were convergently synthesized. The A-ring enyne synthons 19 were synthesized starting with methyl (S)-(+)- or (R)-(-)-3-hydroxy-2-methylpropionate (8). This was converted to the alcohol 14 as a 1:1 epimeric mixture in several steps. After having been separated by column chromatography, each isomer led to the requisite A-ring enyne synthons 19 again as 1:1 mixtures at C-1. Coupling of the resulting A-ring enynes 20a-h with the CD-ring portions 5a,b in the presence of a Pd catalyst afforded the 2-methyl analogues 2a-h and 3a-h in good yield. In this way, all possible A-ring diastereomers were synthesized. The synthesized analogues were biologically evaluated both in vitro and in vivo. The potency was highly dependent on the stereochemistry of each isomer. In particular, the alpha alpha beta-isomer 2g exhibited 4-fold higher potency than 1 alpha,25-dihydroxyvitamin D(3) (1) both in bovine thymus VDR binding and in elevation of rat serum calcium concentration and was twice as potent as the parent compound in HL-60 cell differentiation. Furthermore, its 20-epimer, that is, 20-epi-alpha alpha beta 3g, exhibited exceptionally high activities: 12-fold higher in VDR binding affinity, 7-fold higher in calcium mobilization, and 590-fold higher in HL-60 cell differentiation, as compared to 1 alpha,25-dihydroxyvitamin D(3) (1). Accordingly, the double modification of 2-methyl substitution and 20-epimerization resulted in unique activity profiles. Conformational analysis of the A-ring by (1)H NMR and an X-ray crystallographic analysis of the alpha alpha beta-isomer 2g are also described.