Novel hybrids of natural isochroman-4-one bearing N-substituted isopropanolamine as potential antihypertensive candidates

Resistance-driven innovations in the discovery of bactericides: novel triclosan derivatives decorating isopropanolamine moiety as promising anti-biofilm agents against destructive plant bacterial diseases

BACKGROUND

Controlling bacterial infections in plants is a major challenge owing to the appearance of resistant strains. As a physical barrier, the bacterial biofilm helps bacterial infections acquire drug resistance by enabling bacteria to accommodate complex and volatile environmental conditions and avoid bactericidal effects. Thus, developing new antibacterial agents with antibiofilm potency is imperative.

RESULTS

A series of simple triclosan derivatives containing isopropanolamine moiety were elaborately designed and assessed for their antibacterial behavior. Bioassay results showed that some title compounds had excellent bioactivity against three destructive bacteria Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas axonopodis pv. citri (Xac) and Pseudomonas syringae pv. actinidiae (Psa). Notably, compound C₈ displayed high bioactivities toward Xoo and Xac, with EC₅₀ values were 0.34 and 2.11 μg mL^-1 , respectively. In vivo trials revealed that compound C₈ exhibited excellent protective activities against rice bacterial blight and citrus bacterial canker at 200 μg mL^-1 , with control effectivenesses of 49.57% and 85.60%, respectively. Compound A₄ had remarkably inhibitory activity toward Psa, with an EC₅₀ value of 2.63 μg mL^-1 , and demonstrated outstanding protective activity with a value of 77.23% against Psa in vivo. Antibacterial mechanisms indicated that compound C₈ dose-dependently prevented biofilm formation and extracellular polysaccharide production. C₈ also significantly weakened the motility and pathogenicity of Xoo.

CONCLUSION

This study contributes to the development and excavation of novel bactericidal candidates with broad-spectrum antibacterial activity by targeting bacterial biofilm to control refractory plant bacterial diseases. © 2023 Society of Chemical Industry.

Design, synthesis and biological evaluation of hydrogen sulfide-releasing isochroman-4-one derivatives as new antihypertensive agent candidates

Cardiovascular diseases are increasingly threating the global human health, hypertension is the most important risk factor for cardiovascular and cerebrovascular diseases. To improve the antihypertensive activity and cardiovascular protective effect of natural product (±)-7,8-dihydroxy-3-methyl-isochroman-4-one [(±)-XJP], a series of novel H₂S-releasing isochroman-4-one derivatives were designed and synthesized by coupling hydrogen sulfide (H₂S)-releasing donors with the analogs of (±)-XJP. Further, the H₂S-releasing assay indicated that some target compounds showed excellent H₂S generating ability. Moreover, these novel hybrids exhibited moderate to good in vitro vasodilation efficacy. Among them, the most potent compound exhibited potent in vivo antihypertensive activity with the maximum antihypertensive amplitude about 27%, which was more potent than that of the lead compound (±)-XJP. These results suggested that the hybridization of H₂S-donors and (±)-XJP analogs may provide a promising approach for the discovery of novel antihypertensive agents.

Research progress in biological activities of isochroman derivatives

Isochromans are well recognized heterocyclic compounds in drug discovery which produce diverse therapeutically related applications in pharmacological practices. Medicinal chemistry investigators have synthesized drug-like isochroman candidates with multiple medicinal features including central nervous system (CNS), antioxidant, antimicrobial, antihypertensive, antitumor and anti-inflammatory agents. Simultaneously, SAR (Structure-Activity Relationship) analysis has drawn attentions among medicinal chemists, along with a great deal of derivatives have been derived for potential targets. In this article, we thoroughly summarize the biological activities and part of typical SAR for isochroman derivatives reported on existing literatures and patents, wishing to provide an overall retrospect and prospect on the isochroman analogues.

Design, synthesis and biological evaluation of isochroman-4-one hybrids bearing piperazine moiety as antihypertensive agent candidates

7,8-Dihydroxy-3-methyl-isochromanone-4 (XJP), is a polyphenolic natural product with moderate antihypertensive activity. To obtain new agents with stronger potency and safer profile, we employed XJP and naftopidil as the lead compounds to design and synthesize a novel class of hybrids as antihypertensive agent candidates. In the present study, a series of hybrids (6a-r) of XJP bearing arylpiperazine moiety, which is identified as the pharmacophore of naftopidil, were designed and synthesized as novel α₁-adrenergic receptor antagonists. The biological evaluation showed that target compounds 6c, 6e, 6f, 6g, 6h, 6m and 6q possessed potent in vitro vasodilation potency and α₁-adrenergic receptor antagonistic activity. Furthermore, the most potent compound 6e significantly reduced the systolic and diastolic blood pressure in spontaneously hypertensive rats (SHRs), which was comparable to that of naftopidil, and it had no observable effects on the basal heart rate, suggesting that 6e deserves to be further investigated as a potential clinical candidate for the treatment of hypertension.

Success stories of natural product-based hybrid molecules for multi-factorial diseases

Complex diseases comprises of highly complicated etiology resulting in limited applicability of conventional targeted therapies. Consequently, conventional medicinal compounds suffer major failure when used for such disease conditions. Additionally, development of multidrug resistance (MDR), adverse drug reactions and clinical specificity of single targeted drug therapy has increased thrust for novel drug therapy. In this rapidly evolving era, natural product-based discovery of hybrid molecules or multi-targeted drug therapies have shown promising results and are trending now a days. Historically, nature has blessed human with different sources viz. plant, animal, microbial, marine and ethnopharmaceutical sources which has given a wide variety of medicinally active compounds. These compounds from natural origin are always choice of interest of medicinal chemists because of their minimum side effects. Hybrid molecules synthesized by fusing or conjugating different active molecules obtained from these sources are reported to synergistically block different pathways which contribute in the pathogenesis of complex diseases. This review strives to encompass all natural product-derived hybrid molecules which act as multi-targeting agents striking various targets involved in different pathways of complex diseased conditions reported in literature.

Insights into drug discovery from natural products through structural modification

Natural products (NPs) have played a key role in drug discovery and are still a prolific source of novel lead compounds or pharmacophores for medicinal chemistry. Pharmacological activity and druggability are two indispensable components advancing NPs from leads to drugs. Although naturally active substances are usually good lead compounds, most of them can hardly satisfy the demands for druggability. Hence, these structural phenotypes have to be modified and optimized to overcome existing deficiencies and shortcomings. This review illustrates druggability optimization of NPs through structural modification with some successful examples.

Efficient synthesis of tetrahydronaphthalene- or isochroman-fused spirooxindoles using tandem reactions

The cascade reaction involving a Michael–aldol or vinylogous Henry-acetalization relay is described. We have used the cascade reaction to assemble tetrahydronaphthalene- or isochroman-fused spirooxindoles and other drug-like spirocyclic scaffolds.

First total synthesis of antihypertensive natural products S-(+)-XJP and R-(−)-XJP

The first total synthesis of S-(+)-XJP and R-(−)-XJP has been achieved via intramolecular Heck reaction. A latent functionality strategy was implemented to circumvent the racemization in this endeavor.

Synthesis and β-adrenergic blocking activity of oxime ether hybrids derived from a natural isochroman-4-one

AIM

In a search for new cardiovascular drug candidates, a series of novel oxime ethers derived from a natural isochroman-4-one were synthesized.

METHOD

Compounds 3 and 6, derived from the natural antihypertensive compound 7, 8-dihydroxy-3-methyl-isochroman-4-one (XJP), were designed and synthesized. Subsequently, a series of novel isochroman-4-one oxime ether hybrids were prepared by hybridizing various N-substituted isopropanolamine functionalities to isochroman-4-one oxime. Furthermore, β1-adrenergic blocking activities of the synthesized compounds were assayed using the isolated rat left atria.

RESULTS

Twenty target compounds were obtained, and the preliminary structure-activity relationships were deduced. The most promising compound Ic exhibited β1-adrenoceptor blocking activity (inhibition: 52.2%) at 10(-7) mol·L(-1), which was superior to that of propranolol (inhibition: 49.7%).

CONCLUSION

The results suggested that natural product XJP/isopropanolamine moiety hybrids may provide a promising approach for the discovery of novel cardiovascular drug candidates.