Boronate derivatives of functionally diverse catechols: stability studies

Theoretical Coupling and Stability of Boronic Acid Adducts with Catecholamines

Background:

Catecholamines combined with boric/boronic acids are attractive chemical agents in drug design because some of their adducts have shown interesting biological activity. Scant information exists about their stability.

Objective:

The aim of the present theoretical study was to explore the role of boron in molecules that combine catecholamines and boric/boronic acids, with a particular interest in examining stability.

Method:

The methodology was based on the US GAMESS program using DFT with the B3LYP exchange-correlation functional and the 6-31G (d,p) split-valence basis set.

Results:

According to the current findings, the boron-containing compounds (BCCs) exhibit weaker bonding to the hydroxyls on the ethylamine moiety than to those in the aromatic ring. The strongest binding site of a hydroxyl group was often found to be in meta-position (relative to ethylamine moiety) for boron-free compounds and in para-position for BCCs. Nonetheless, the methyl substituent in the amino group was able to induce changes in this pattern. We analyzed feasible boronsubstituted structures and assessed the relative strength of the respective C-B bonds, which allowed for the identification of the favorable points for reaction and stability.

Conclusion:

It is feasible to form adducts by bonding on the amine and catechol sides of catecholamines. The presence of boron stabilizes the adducts in para-position. Since some of these BCCs are promising therapeutic agents, understanding the mechanisms of reaction is relevant for drug design.

Boron's journey: advances in the study and application of pharmacokinetics

Boron-containing compounds (BCCs) are attractive chemical entities in drug development. Some of these compounds have been used in the treatment of human disease, and studies on their pharmacodynamics suggest that they employ multiple forms of activity. However, less is known about the pharmacokinetic profile of these molecules. Areas covered: The herein compiled reported data is presented in accordance with the classical 'ADME' system for identifying the scope of BCCs in the respective fields. Our analysis suggests that these compounds have several distinct ways to move within the human body, and that the specific structural features of each molecule account for its distinct pharmacokinetic profile. These insights should be useful for designing BCCs with a desired effect. Expert opinion: Increasing knowledge about the pharmacokinetics of BCCs is providing a broader understanding about the design of new release systems and potential drugs, as well as probable protein transporters that could be related to key roles in physiological processes. These transporters may be involved in sodium transport, hormone release and regulation of the cell cycle. The shared features among groups of BCCs are being identified in order to apply these insights to the design of advantageous compounds.

Boron-containing compounds: chemico-biological properties and expanding medicinal potential in prevention, diagnosis and therapy

INTRODUCTION

Although the medicinal use of boron-containing compounds (BCCs) had long been limited to antiseptics, in the last few decades, these compounds have been used as antibiotics or chemotherapeutic agents. In the last few years, boron has been included in the moieties of many known drugs to improve their capacity in binding to their respective target receptors.

AREAS COVERED

The current review focuses on research and patent literature of the last decade related to the development of BCCs as preventive, diagnostic and therapeutic tools. It explores the possible mechanisms of action of these compounds as well as the advantageous features of their structure and chemico-pharmacological properties.

EXPERT OPINION

Although uncertainties exist about the mechanism of action of BCCs, increasing evidence about their toxicological profile strongly suggests that many can be safely administered to humans. Even stronger evidence exists regarding the capacity of BCCs to reach multiple targets that are involved in the treatment of common diseases. It seems fair to say that some BCCs will reach the market for medicinal use in the near future, not only for targeting microbial or neoplastic systems but also for acting on cell-signaling processes involved in many other disorders.

17-Deoxoestrone [estra-1,3,5(10)-trien-3-ol]-methanol (3/1)

Three independent mol­ecules of the title estrone derivative and a mol­ecule of methanol comprise the asymmetric unit of the title compound [systematic name: 13-methyl-6,7,8,9,11,12,13,14,15,16-deca­hydro­cyclo­penta­[a]phenanthren-3-ol–meth­an­ol (3/1)], 3C₁₈H₂₄O·CH₃OH. Two of the estrone mol­ecules exhibit 50:50 disorder (one displays whole-mol­ecule disorder and the other partial disorder in the fused five- and six-membered rings) so that five (partial) mol­ecular conformations are discernable. The conformation of the six-membered ring abutting the aromatic ring is close to a half-chair in all five components. The conformation of the six-membered ring fused to the five-membered ring is based on a chair with varying degrees of distortion ranging from minor to significant. Two distinct conformations are found for the five-membered ring: in four mol­ecules, the five-membered ring is twisted about the bond linking it to the six-membered ring, and in the other, the five-membered ring is an envelope with the quaternary C atom being the flap atom. The crystal packing features O—H⋯O hydrogen bonding whereby the four mol­ecules comprising the asymmetric unit are linked into a supra­molecular chain along the b axis.

3β-Acet-oxy-6-hy-droxy-imino-cholestane

Two independent mol­ecules comprise the asymmetric unit of the title cholestane derivative, C₂₉H₄₉NO₃ {systematic name: (3S,8S,9S,10R,13R,14S,17R)-17-[(1R)-1,5-dimethyl­hex­yl]-6-hy­droxy­imino-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetra­deca­hydro-1H-cyclo­penta­[a]phenanthren-3-yl ace­tate}. The major differences between the mol­ecules relate to the relative orientations of the terminal acetyl [C—C—O—C torsion angles = −158.8 (3) and −81.7 (3)°] and alkyl groups [C—C—C—C = 168.9 (3) and 65.8 (4)°]. In the crystal, the independent mol­ecules associate via pairs of O—H⋯N hydrogen bonds, forming dimeric aggregates. Supra­molecular layers in the ab plane are mediated by C—H⋯O inter­actions.

3-Methyl-5α-cholest-2-ene

In the title cholestane derivative, C(28)H(48) [systematic name: (1S,2S,7R,10R,11R,14R,15R)-2,5,10,15-tetra-methyl-14-[(2R)-6-methyl-heptan-2-yl]tetra-cyclo-[8.7.0.0(2,7).0(11,15)]hepta-dec-4-ene], the cyclo-hexene ring adopts a half-chair conformation. The parent 5α-cholest-2-ene and the equivalent fragment of the title compound are almost superimposable (r.m.s. deviation = 0.033 Å).