A new benzophenone, and the antiplasmodial activities of the constituents of Securidaca longipedunculata fresen (Polygalaceae)

The new pattern for dual NOTCH pathway involving nuclear transcription and mitochondrial regulation supports therapeutic mechanism of 4-butyl benzophenone derivatives against SIRS

The systemic inflammatory response syndrome (SIRS) represents a self-amplifying cascade of inflammatory reactions and pathophysiological states triggered by infectious or non-infectious factors. The identification of disease targets and differential proteins in the liver (the unique and important immune organ) of SIRS mice treated with the lead compound D1 was conducted using the Genecards database and proteomic analysis, respectively. Subsequently, NOTCH1 was identified as the potential hub target via an intersection analysis between the aforementioned differentially expressed proteins and disease targets. Based on our previous research on the structure-activity relationship, we designed and synthesized a series of SIRS-related derivatives, wherein butyl, halogen, and ester groups were incorporated into benzophenone, aiming at exploring the anti-inflammatory protective action from the perspective of macrophage polarization. Notably, these derivatives exhibited a direct binding capability to the O-glucosylation site (SER496) or its vicinities (such as SER492, VAL485) of NOTCH1 using docking, SPR, DARTS, and CETSA techniques. Mechanistically, derivative D6 exerted anti-inflammatory effects via the dual NOTCH pathway. Firstly, it could inhibit NOTCH1 nuclear transcriptional activity, attenuate the interaction between NICD and RBPJK, concurrently suppress NF-κB and NLRP3 inflammasome (NLRP3, ASC, and cleaved CASP1) activation, and promote NICD (NOTCH1 active fragments) ubiquitination metabolism (the nuclear transcriptional pathway). Secondly, it might possess the ability to increase PGC1α level, subsequently, enhance ATP and MMP levels, mitigate ROS production, increase mitochondrial numbers, and ameliorate mitochondrial inflammatory damage (the mitochondrial pathway). Importantly, the activator Jagged1 could effectively reverse the aforementioned effects, while the inhibitor DAPT exhibited a synergistic effect, suggesting that the nuclear transcriptional regulation and mitochondrial regulation were both in a NOTCH1-dependent manner. Subsequently, it effectively alleviated the inflammatory response and preserved organ function as evidenced by up-regulating M2-type macrophage-related anti-inflammatory cytokines (IL10, TGFβ, CD206, and ARG1) and down-regulating M1-type macrophage-related pro-inflammatory cytokines (NO, IL6, IL18, iNOS, TNFα, CD86, and IL1β). In a word, derivative D6 modulated macrophage polarization and effectively mitigated SIRS by targeting inhibition of the dual NOTCH pathway.

Inhibition of Seizure-Like Paroxysms and Toxicity Effects of Securidaca longepedunculata Extracts and Constituents in Zebrafish Danio rerio

Plants used in traditional medicine in the management of epilepsy could potentially yield novel drug compounds with antiepileptic properties. The medicinal plant Securidaca longepedunculata is widely used in traditional medicine in the African continent, and epilepsy is among several indications. Limited knowledge is available on its toxicity and medicinal effects, such as anticonvulsant activities. This study explores the potential in vivo inhibition of seizure-like paroxysms and toxicity effects of dichloromethane (DCM) and ethanol (EtOH) extracts, as well as isolated xanthones and benzoates of S. longepedunculata. Ten phenolic compounds were isolated from the DCM extract. All of the substances were identified by nuclear magnetic resonance spectroscopy. Assays for toxicity and inhibition of pentylenetetrazole (PTZ)-induced seizure-like paroxysms were performed in zebrafish larvae. Among the compounds assessed in the assay for maximum tolerated concentration (MTC), benzyl-2-hydroxy-6-methoxy-benzoate (MTC 12.5 μM), 4,8-dihydroxy-1,2,3,5,6-pentamethoxyxanthone (MTC 25 μM), and 1,7-dihydroxy-4-methoxyxanthone (MTC 6.25 μM) were the most toxic. The DCM extract, 1,7-dihydroxy-4-methoxyxanthone and 2-hydroxy-1,7-dimethoxyxanthone displayed the most significant inhibition of paroxysms by altering the locomotor behavior in GABAA receptor antagonist, PTZ, which induced seizures in larval zebrafish. The EtOH extract, benzyl benzoate, and benzyl-2-hydroxy-6-methoxy-benzoate unexpectedly increased locomotor activity in treated larval zebrafish and decreased locomotor activity in nontreated larval zebrafish, seemingly due to paradoxical excitation. The results reveal promising medicinal activities of this plant, contributing to our understanding of its use as an antiepileptic drug. It also shows us the presence of potentially new lead compounds for future drug development.

SIRT1-dependent mitochondrial biogenesis supports therapeutic effects of 4-butyl-polyhydroxybenzophenone compounds against NAFLD

The mitochondria have been identified as key targets in nonalcoholic fatty liver disease (NAFLD), one of the most prevalent chronic liver damage diseases globally. Meanwhile, the biological information analysis in this study revealed that SIRT1, PPARG, PPARA, and PPARGC1A (mitochondrial biogenesis-related proteins) were NAFLD therapeutic targets. Therefore, the design and synthesis of targeted drugs that promote mitochondrial biogenesis and improve mitochondrial function are particularly important for NAFLD treatment. Recently, we introduced butyls, hydroxyls, and halogens to benzophenone and synthesized a series of NAFLD-related 4-butylpolyhydroxybenzophenone compounds, aiming at investigating the hepatoprotective activity from the aspect of mitochondrial biogenesis. The structure-activity relationship demonstrated that hydroxyl and ketone groups were active groups interacting with mitochondrial biogenesis proteins (SIRT1 and PGC1α), and the activity was stronger when the o-hydroxyl group was present on the benzene ring. In contrast, the activity was little affected by the presence of the p-hydroxyl group, m-hydroxyl group, butyl group type, or halogen. In addition, in vitro studies confirmed that these compounds could directly bind to SIRT1 and PGC1α, markedly promote their interaction, significantly increase the expression of proteins and genes related to mitochondrial biogenesis (SIRT1, PGC1α, NRF1, TFAM, COX1, and ND6) and subsequently ameliorate mitochondria dysfunction, which was evidenced by the decreased ROS, upregulated ATP production, increased MMP, and enhanced mitochondrial number. According to the outcomes of our in vitro and in vivo experiments, 4-butyl-polyhydroxybenzophenone compounds could also effectively reduce the formation of lipid droplets and liver injury index (ALT, AST, LDH, AKP, γ-GT, and GDH) and improve the level of antioxidant enzymes (GSH and SOD). Particularly, the treatment of these compounds after a high-fat diet could significantly reduce body weight, decrease liver coefficient, attenuate liver damage, and ameliorate lipid accumulation in rat liver, demonstrating their therapeutic effects on NAFLD. Mechanistically, 4-butyl-polyhydroxybenzophenone compounds promoted mitochondrial biogenesis and eventually prevented NAFLD liver injury by activating the PGC1α signaling pathway in a SIRT1-dependent manner, which was strongly supported by SIRT1 inhibitor EX527.

Synergism in Antiplasmodial Activities of Artemether and Lumefantrine in Combination with Securidaca longipedunculata Fresen (Polygalaceae)

Malaria is the most lethal parasitic disease in the world. The frequent emergence of resistance by malaria parasites to any drug is the hallmark of sustained malaria burden. Since the deployment of artemisinin-based combination therapies (ACTs) it is clear that for a sustained fight against malaria, drug combination is one of the strategies toward malaria elimination. In Sub-Saharan Africa where malaria prevalence is the highest, the identification of plants with a novel mechanism of action that is devoid of cross-resistance is a feasible strategy in drug combination therapy. Thus, artemether and lumefantrine were separately combined and tested with extracts of Securidaca longipedunculata, a plant widely used to treat malaria, at fixed extract-drug ratios of 4:1, 3:1, 1:1, 1:2, 1:3, and 1:4. These combinations were tested for antiplasmodial activity against three strains of Plasmodium falciparum (W2, D6, and DD2), and seven field isolates that were characterized for molecular and ex vivo drug resistance profiles. The mean sum of fifty-percent fractional inhibition concentration (FIC50) of each combination and singly was determined. Synergism was observed across all fixed doses when roots extracts were combined with artemether against D6 strain (FIC50 0.403 ± 0.068) and stems extract combined with lumefantrine against DD2 strain (FIC50 0.376 ± 0.096) as well as field isolates (FIC50 0.656 ± 0.067). Similarly, synergism was observed in all ratios when leaves extract were combined with lumefantrine against W2 strain (FIC50 0.456 ± 0.165). Synergism was observed in most combinations indicating the potential use of S. longipedunculata in combination with artemether and lumefantrine in combating resistance.