Design, Synthesis, and Activity Study of Cinnamic Acid Derivatives as Potent Antineuroinflammatory Agents

Discovery of Cinnamic Acid Derivatives as Potent Anti-H. pylori Agents

Antibiotics are currently used for the treatment of Helicobacter pylori (H. pylori), which is confirmed to be the major cause of gastric disorders. However, the long-term consumption of antibiotics has already caused antibiotic resistance and side effects in vivo. Therefore, there is an emerging need for searching for safe and effective anti-H. pylori agents. Inspired by the excellent bioactivities of cinnamic acid, a series of cinnamic acid derivatives (compounds 1-30) were synthesized and determined for H. pylori inhibition. The initial screening revealed that compound 23, a 2,4-dinitro cinnamic acid derivative containing 4-methoxyphenol, showed excellent H. pylori inhibition with an MIC value of 4 μM. Further studies indicated that compound 23 showed anti-bacterial activity and had a bactericidal effect on H. pylori due to the destruction of the bacterial structure. Molecular docking analysis revealed that the 2,4-dinitro groups in cinnamic acid moiety formed hydrogen bonding with amino acid residues in an active pocket of H. pylori protein. Interestingly, the ester moiety fitted into the hydrophobic pocket, attaining additional stability to compound 23. Above all, the present study reveals that compound 23 could be considered a promising anti-H. pylori agent to treat H. pylori causing gastritis.

Synthesis, characterization, and biological evaluation of novel cinnamic acid derivatives: cinnamoyl-metronidazole ester and cinnamoyl-memantine amide

In this study, two derivatives, namely the ester derivative cinnamoyl metronidazole and the amide derivative cinnamoyl memantine, were synthesized from cinnamic acid and respective drugs for the purpose of exploring their potential as novel and efficient antimicrobial agents in the quest of prevailing the global antimicrobial resistance challenge. The synthesis process involved two steps: first, the chlorination of cinnamic acid using thionyl chloride, and second, the esterification of metronidazole or the amidation of memantine. These steps resulted in the formation of cinnamoyl metronidazole/memantine. Optimal reaction conditions were established, and chromatographic techniques were used to separate the synthesized compounds. Confirmation of successful synthesis was achieved through FT-IR analysis, which readily distinguished the chlorinated product and derivatives based on distinctive bands, including mainly the one of carbonyl group. Additionally, molecular structures were validated using 1H NMR and 13C NMR, with all peaks further confirming the successful esterification/amidation of cinnamoyl and drug moieties. Upon evaluating the biological activity, the parent compounds exhibited negligible effects within the tested concentration range. However, the derivatives demonstrated significant activity. The ester derivative exhibited potent activity against the Gram-positive bacterium Staphylococcus aureus, as evidenced by a zone of inhibition measuring 12-15 mm in diameter. Conversely, the amide derivative displayed appreciable biological activity against Candida fungi, with an inhibition zone measuring 11-14 mm.

Simple phenylpropanoids: recent advances in biological activities, biosynthetic pathways, and microbial production

Covering: 2000 to 2023Simple phenylpropanoids are a large group of natural products with primary C6-C3 skeletons. They are not only important biomolecules for plant growth but also crucial chemicals for high-value industries, including fragrances, nutraceuticals, biomaterials, and pharmaceuticals. However, with the growing global demand for simple phenylpropanoids, direct plant extraction or chemical synthesis often struggles to meet current needs in terms of yield, titre, cost, and environmental impact. Benefiting from the rapid development of metabolic engineering and synthetic biology, microbial production of natural products from inexpensive and renewable sources provides a feasible solution for sustainable supply. This review outlines the biological activities of simple phenylpropanoids, compares their biosynthetic pathways in different species (plants, bacteria, and fungi), and summarises key research on the microbial production of simple phenylpropanoids over the last decade, with a focus on engineering strategies that seem to hold most potential for further development. Moreover, constructive solutions to the current challenges and future perspectives for industrial production of phenylpropanoids are presented.

Design, synthesis and evaluation of ursodeoxycholic acid-cinnamic acid hybrids as potential anti-inflammatory agents by inhibiting Akt/NF-κB and MAPK signaling pathways

A series of ursodeoxycholic acid (UDCA)-cinnamic acid hybrids were designed and synthesized. The anti-inflammatory activity of these derivatives was screened through evaluating their inhibitory effects of LPS-induced nitric oxide production in RAW264.7 macrophages. The preliminary structure-activity relationship was concluded. Among them, 2m showed the best inhibitory activity against NO (IC50 = 7.70 μM) with no significant toxicity. Further study revealed that 2m significantly decreased the levels of TNF-α, IL-1β, IL-6 and PGE2, down-regulated the expression of iNOS and COX-2. Preliminary mechanism study indicated that the anti-inflammatory activity of 2m was related to the inhibition of the Akt/NF-κB and MAPK signaling pathway. Furthermore, 2m reduced inflammation by a mouse model of LPS-induced inflammatory disease in vivo. In brief, our findings indicated that 2m might serve as a new lead compound for further development of anti-inflammatory agents.

Discovery of acylated isoquercitrin derivatives as potent anti-neuroinflammatory agents in vitro and in vivo

Neuroinflammation is considered as an important pathological mechanism in neurodegenerative diseases. The natural isoquercitrin (IQ) was reported to have potential anti-neuroinflammatory activity. The acylation of glycoside in IQ enhanced its hydrophobicity, which was expected to enhance the protective effect against inflammation. In this study, three carboxylic acids with anti-neuroinflammatory effects including cinnamic acid, ibuprofen (IBU) and acetylsalicylic acid were introduced into the 6''-OH of IQ through the corresponding vinyl esters intermediates (8a-8c). Ultimately, the acylated IQ derivatives (Compound 9a-9c) were obtained with 35-42% yields using immobilized lipase Novozym 435 as catalyst. Subsequently, their anti-neuroinflammatory activities were evaluated in lipopolysaccharide (LPS)-induced BV2 cells. Compound 9b improved cell viability in the range of ≤50 μM and significantly decreased NO, PGE2 production and TNF-α, IL-1β release and oxidative stress level with a concentration-dependent manner. Also, it could downregulate iNOS, COX-2, TNF-α and IL-1β expression levels, approximately 40% reduction were achieved when 15μM compound 9b was employed. In addition, compound 9b resisted phosphorylation and degradation of IkBαs, suppressing the activation of NF-κB signaling pathway, exhibiting excellent neuroinflammatory inhibition. Moreover, the administration of compound 9b (30, 60 mg/kg) alleviated behavioral disorders and neuronal damages in LPS-induced neuroinflammatory mice. Meanwhile, the decreased TNF-α, IL-1β release, expression and the inhibited glial cells activation were obtained in compound 9b-treated group, which was superior to that of IQ or IBU. Overall, these findings demonstrated that compound 9b, formed by the introduction of ibuprofen into IQ, can serve as a novel promising therapeutic agent for anti-neuroinflammation.

Discovery of Coixol Derivatives as Potent Anti-inflammatory Agents

Coixol, a derivative of 2-benzoxazolinone extracted from coix (Coix lachryma-jobi L. var. ma-yuen Stapf), has demonstrated promising anti-inflammatory activity and low cytotoxicity. In this study, 26 coixol derivatives were designed and synthesized by hybridization with cinnamic acid to identify new anti-inflammatory agents. The anti-inflammatory activities of the derivatives were screened using LPS-induced overexpression of nitric oxide (NO) in RAW264.7 macrophages. On the basis of the screening results, compounds containing furan (9c) or nitrofuran (9j) moieties displayed more pronounced activity than coixol and celecoxib. Mechanistic investigations revealed that 9c and 9j suppressed the expression of induced nitric oxide synthase (iNOS), tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β, which was associated with the inhibition of the nuclear factor (NF)-κB signaling pathway. In vivo studies confirmed the anti-inflammatory activity of 9c and 9j in a xylene-induced mice auricles edema model. The preliminary in vitro and in vivo research findings suggest that 9c and 9j have the potential to be developed as anti-inflammatory agents.

Synthesis, Anti-Tyrosinase Activity, and Spectroscopic Inhibition Mechanism of Cinnamic Acid-Eugenol Esters

Tyrosinase plays crucial roles in mediating the production of melanin pigment; thus, its inhibitors could be useful in preventing melanin-related diseases. To find potential tyrosinase inhibitors, a series of cinnamic acid-eugenol esters (c1~c29) was synthesized and their chemical structures were confirmed by 1H NMR, 13C NMR, HRMS, and FT-IR, respectively. The biological evaluation results showed that all compounds c1~c29 exhibited definite tyrosinase inhibitory activity; especially, compound c27 was the strongest tyrosinase inhibitor (IC50: 3.07 ± 0.26 μM), being ~4.6-fold stronger than the positive control, kojic acid (IC50: 14.15 ± 0.46 μM). Inhibition kinetic studies validated compound c27 as a reversible mixed-type inhibitor against tyrosinase. Three-dimensional fluorescence and circular dichroism (CD) spectra results indicated that compound c27 could change the conformation and secondary structure of tyrosinase. Fluorescence-quenching results showed that compound c27 quenched tyrosinase fluorescence in the static manner with one binding site. Molecular docking results also revealed the binding interactions between compound c27 and tyrosinase. Therefore, cinnamic acid-eugenol esters, especially c27, could be used as lead compounds to find potential tyrosinase inhibitors.

Naproxen-Derived New Compound Inhibits the NF-κB, MAPK and PI3K/Akt Signaling Pathways Synergistically with Resveratrol in RAW264.7 Cells

Naproxen is widely used for anti-inflammatory treatment but it can lead to serious side effects. To improve the anti-inflammatory activity and safety, a novel naproxen derivative containing cinnamic acid (NDC) was synthesized and used in combination with resveratrol. The results showed that the combination of NDC and resveratrol at different ratios have a synergistic anti-inflammatory efficacy in RAW264.7 macrophage cells. It was indicated that the combination of NDC and resveratrol at a ratio of 2:1 significantly inhibited the expression of carbon monoxide (NO), tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), induced nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2) and reactive oxygen species (ROS) without detectable side effects on cell viability. Further studies revealed that these anti-inflammatory effects were mediated by the activation of nuclear factor kappa-B (NF-κB), mitogen-activated protein kinase (MAPK) and phosphoinositide-3 kinase (PI3K)/protein kinase B (Akt) signaling pathways, respectively. Taken together, these results highlighted the synergistic NDC and resveratrol anti-inflammatory activity that could be further explored as a strategy for the treatment of inflammatory disease with an improved safety profile.

Anti-Neuroinflammatory Potential of Natural Products in the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is an age-related chronic progressive neurodegenerative disease, which is the main cause of dementia in the elderly. Much evidence shows that the onset and late symptoms of AD are caused by multiple factors. Among them, aging is the main factor in the pathogenesis of AD, and the most important risk factor for AD is neuroinflammation. So far, there is no cure for AD, but the relationship between neuroinflammation and AD may provide a new strategy for the treatment of AD. We herein discussed the main etiology hypothesis of AD and the role of neuroinflammation in AD, as well as anti-inflammatory natural products with the potential to prevent and alleviate AD symptoms, including alkaloids, steroids, terpenoids, flavonoids and polyphenols, which are available with great potential for the development of anti-AD drugs.