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Low‐molecular‐weight synthetic molecules 1 with the general 2‐(fluorophenylamino)‐4,6‐disubstituted 1,3,5‐triazine structure and showing anti‐inflammatory and anticancer activities were explored. Structure–activity relationship studies demonstrated the importance of the aminopentyl chain, the 3‐ or 4‐fluorophenylaniline component, and the presence of at least one substituent, such as a tyramine moiety, attached directly to the triazine ring as essential for good activity. These compounds, represented by leads 4‐{2‐[4‐(5‐Aminopentylamino)‐6‐(3‐fluorophenylamino)‐1,3,5‐triazin‐2‐ylamino]ethyl}phenol (6) and 4‐{2‐[4‐(5‐Aminopentylamino)‐6‐(4‐fluorophenylamino)‐1,3,5‐triazin‐2‐ylamino]ethyl}phenol (10), displayed moderate and significant in vitro and in vivo dual activities, respectively, and address the molecular link between inflammation and cancer. Compound 10 demonstrated significant antitumor efficacy upon administration by the oral and intravenous routes in several animal models. This class of triazine compounds is new, safe, and nontoxic and offers a novel approach to the treatment of inflammation and cancer.

PTH is regarded conventionally as a catabolic hormone that stimulates osteoclastic resorption of bone. However, it has been known since 1932 that intermittent pulses of PTH stimulate bone formation in animals and humans. PTH independently activates two signal mechanisms: one that stimulates adenylyl cyclase and one that stimulates protein kinase C (PKC). The goal of this study was to use the 3- to 5-month-old ovariectomized (OVX) rat model to determine which of the two signal mechanisms is responsible for the anabolic action of PTH on bone. OVX triggered a large loss of trabecular bone without significantly affecting the normal slow growth of cortical bone in the distal halves of the femora. Daily injections of human hPTH(1-34) fragment (1 nmol/100 g body weight), which stimulated both adenylyl cyclase and membrane-associated PKC activity in osteoblast-like ROS 17/2 rat osteosarcoma cells, stimulated the growth of both cortical and trabecular bone in the OVX rats. Daily injections of the same dose of hPTH(1-31), which stimulated adenylyl cyclase but not PKC in ROS 17/2 cells, stimulated trabecular bone growth in the OVX rats less effectively than hPTH(1-34), but it stimulated cortical bone growth as rapidly and as dramatically as hPTH(1-34). Injections of equimolar amounts of desamino-hPTH(1-34) [N-propionyl(2-3)hPTH-amide], which stimulated PKC as strongly as hPTH(1-34) in ROS 17/2 cells but had a drastically reduced ability to stimulate adenylyl cyclase, or injections of recombinant hPTH(8-84) which stimulated PKC only in the ROS 17/2 cells, did not stimulate cortical or trabecular bone growth in the OVX animals. Thus, cyclic AMP and cyclic AMP-dependent protein kinases may be the primary mediators of the anabolic action of intermittent pulses of PTH on bone in OVX rats.

Five analogues of human parathyroid hormone (hPTH-(20-34)-NH2, I; cyclo[Lys26-Asp30]-hPTH-(20-34)-NH2, II; cyclo[Glu22-Lys26]-hPTH-(20-34)-NH2, III; cyclo[Lys27-Asp30]- hPTH-(20-34)-NH2, IV; and [Leu27]-hPTH-(20-34)-NH2 V) were tested for their ability to promote membrane-bound protein kinase C (PKC) activity in a rat osteosarcoma cell line (ROS 17/2). Analogues I, II and V stimulated PKC activity in the picomolar range, whereas analogues III and IV did not stimulate this activity at any concentration tested. The circular dichroism spectra in neutral, aqueous buffer showed an increase in alpha-helix in analogues II, III and V as compared to I; this increase appeared to be in the region of the cyclic lactam structure. Analogue IV did not adopt a helical structure, even in the presence of 40% trifluoroethanol, a helix-promoting solvent. The remaining analogues showed a three- to four-fold enhancement of alpha-helix in this solvent. Analogues II and III had increased retention times in reversed-phase chromatography, as compared to I and IV. This is consistent with a stabilization of amphiphilic helix in analogues II and III compared with I and IV. The data suggest that in the region bounded approximately by residues 24-32, an amphiphilic alpha-helix is important for correct functional binding to the PTH receptor.

A series of 6-substituted purinyl alkoxycarbonyl amino acids were synthesized and evaluated for their ability to stimulate cytotoxic T lymphocytes (CTLs) and the mixed lymphocyte reaction (MLR). A few of these compounds, in particular [[5-[6-(N,N-dimethylamino)purin-9-yl]pentoxy]carbonyl]d-arginine (BCH-1393, 4a), displayed an in vitro stimulation of CTLs comparable to interleukin 2 (IL 2). BCH-1393 increased the CTL response between 10-9 M and 10-5 M. Further, this potent in vitro activity was reflected as a significant increase in CTL cell number in vivo. However, immunophenotyping of some of the other equipotent compounds did not reveal a parallel relative increase in CTLs in vivo. It was difficult to formulate a rigorous structure−activity relationship based on in vitro CTL activity. Nevertheless, the activity was dependent upon the nature of the 6-substituent on the purine, the type and stereochemistry of the amino acid, and the distance and spatial freedom between the purine and amino acid as define...

Imreg (Tyr1-Gly2-Gly3) is a well-known immunostimulant. However, it possesses a short half-life. Stabilized analogues of Imreg were prepared by a regioselective insertion in which peptide bonds at position 1,2 or 2,3 were replaced by thioamide linkages. This was achieved by using new thioacylating agents based on thioacyl-fluoro-N-benzimidazolone. The synthesis and properties of these reagents are described herein. This peptide modification enhanced significantly the half-life of the thioanalogues relative to Imreg in blood. The thioanalogues and Imreg were tested in vitro in T and B cell proliferation assays and for their ability to stimulate cytotoxic T-lymphocytes (CTLs). Only thiotyrosyl glycyl glycine 11 displayed some activity as evidenced by a weak stimulation of CTLs. On the basis of this activity and the increased stability, an in vivo immunological evaluation was undertaken. Immunophenotyping of 11 revealed a significant increase in activated CTL and NK cell populations in the spleen. This expansion was also accompanied by a significant stimulation of NK cells and the B cell proliferative response. Thioanalogues of Imreg were generally nontoxic, as exemplified by 11. The latter is a promising immunostimulant which may be targeted for cancer and viral infections, where CTLs and NK cells play an important role, or as a vaccine adjuvant where stimulation of antibody-producing B cells is important.