Swietenine and swietenolide from Swietenia macrophylla king improve insulin secretion and attenuate apoptosis in H2 O2 induced INS-1 cells

Swietenine improved the progression of diabetic nephropathy through inhibiting ferroptosis via activating Akt/GSK-3β/Nrf2 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Swietenia macrophylla King is a traditional medicinal plant extensively utilized in Asia and its pharmacological properties primarily involve antidiabetic, anti-inflammatory, antioxidant, antibacterial, and antitumor effects. Swietenine (Swi), the major bioactive compound presents in the fruits of S. macrophylla, has demonstrated beneficial therapeutic effects on diabetic nephropathy (DN). However, the underlying mechanism through which Swi influences DN remains unclear.

AIM OF THE STUDY

The current research aims to investigate the effects of Swi on DN and explore its underlying mechanisms associated with ferroptosis, both in vivo and in vitro.

METHODS

A model of streptozotocin/high-fat diet (STZ/HFD)-induced Sprague-Dawley (SD) rats was employed to assess the effect of Swi on improving DN and resisting ferroptosis in vivo. Additionally, mouse podocyte cells (MPC-5 cells) were induced by high glucose (HG) and cultured to explore the potential mechanisms of Swi in treating DN in vitro. To further validate the protective effects of Swi, pathway-specific inhibitors were administered to HG-induced MPC-5 cells to confirm the involvement of the Akt/GSK-3β/Nrf2 signaling pathway in the inhibition of ferroptosis. A combination of proteomics, immunohistochemical staining, western blotting, and cell culture techniques was utilized to explore the pharmacological mechanisms of Swi. Furthermore, network pharmacology and molecular docking analyses were conducted to predict the targets of Swi in relation to DN, which were subsequently validated through Western blotting analysis.

RESULTS

Administration of Swi significantly enhanced renal function and ameliorated pathological alterations in DN rats, as well as improved oxidative stress and inhibited ferroptosis. In vitro studies revealed that Swi dramatically improved the cell viability and mitigated oxidative stress, and inhibited ferroptosis via activating the Akt/GSK-3β/Nrf2 signaling pathway in HG-induced MPC-5 cells.

CONCLUSION

This study demonstrates that Swi improves DN by inhibiting ferroptosis via activating Akt/GSK-3β/Nrf2 signaling pathway for the first time, thereby providing a scientific basis that Swi is expected to be a promising candidate drug for the treatment of DN.

Effects of Flurochloridone on the Developmental Toxicity in Zebrafish (Danio rerio) Embryo

Flurochloridone (FLC) is a selective herbicide that can cause reproductive toxicity in male rats. However, limited information is available regarding the toxicity of FLC in the developmental stages of aquatic organisms. This study aimed to investigate the effects of FLC exposure during embryonic development and elucidate its potential mechanism of action. Zebrafish embryos were exposed to 6.25, 12.5, 25, and 50 μg/mL FLC for 4-144 hpf. The developmental status of embryos was recorded; the indicators of oxidative stress and embryonic apoptosis were determined. We found that FLC exposure caused severe embryonic malformations, such as pericardial edema, spinal curvature, and growth retardation, accompanied by a decreased hatching and survival rate. After exposure until 144 h postfertilization, the median lethal concentration (LC50) of FLC in zebrafish embryos was 36.9 μg/mL. Subsequently, FLC induced the accumulation of reactive oxygen species and malondialdehyde, enhanced the activity of superoxide dismutase, and activated the Keap1-Nrf2 signaling pathway. Further studies confirmed that FLC can induce apoptosis in zebrafish embryos through the activation of caspase. These results suggest that FLC induced developmental toxicity in zebrafish embryos, which provides new evidence regarding FLC toxicity in aquatic organisms and to assess human health risks.

Swietenolide inhibits the TXNIP/NLRP3 pathways via Nrf2 activation to ameliorate cognitive dysfunction in diabetic mice

Oxidative stress and inflammation play important roles in diabetic-associated cognitive dysfunction (DACD). Swietenolide (Std), isolated from the fruit of Swietenia macrophylla King, exhibits various potent pharmacological activities, including antioxidant, anti-inflammatory, and anti-tumor properties. However, the effects of Std on DACD remains unexplored. We utilized diabetic db/db mice and the hippocampal cell line HT22 to evaluate the effects and underlying molecular mechanisms of Std on DACD. Molecular docking study, western blotting, immunohistochemistry, and enzyme-linked immunosorbent assay analyses were conducted to elucidate the molecular mechanisms involved. We found that Std significantly improved cognitive dysfunction in diabetic mice and increased cell viability in HT22 cells under high glucose condition. The reduction in superoxide dismutase (SOD) enzamy activity and glutathione (GSH) level, along with an increase in malondialdehyde (MDA) induced by high glucose in hippocampus, were reversed by Std treatment. Furthermore, Std effectively diminished the levels of proinflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Importantly, Std markedly activated the Nrf2 pathway to inhibit the thioredoxin-interacting protein/NOD-like receptor protein 3 (TXNIP/NLRP3) pathways. However, the neuroprotective effect of Std was significantly weakened by Nrf2 inhibitor ML385. These results indicate that Std provides substantial protection against high glucose-induced hippocampal injury by inhibiting the TXNIP/NLRP3 pathways dependent on Nrf2, which may serve as a promising agent for attenuating DACD.

Swietenine inhibited oxidative stress through AKT/Nrf2/HO-1 signal pathways and the liver-protective effect in T2DM mice: In vivo and in vitro study

Swietenia macrophylla King, belongs to the Meliaceae family, is a valuable medicinal plant and its fruits have been processed commercially to a variety of health foods. The seeds have long been known for their ethnomedicinal significance against these diseases. Swietenine (Swi) was isolated from S. macrophylla and could ameliorate inflammation and oxidative stress. In this study, HepG2 cells induced by H₂ O₂ were used to construct oxidative stress model in vitro. The aim of this study was to investigate the protective effect of Swi on H₂ O₂ induced oxidative injury in HepG2 cells and its molecular mechanism, and to explore the effect of Swi on liver injury in db/db mice and its possible mechanism. The results showed that Swi significantly inhibited HepG2 cells viability and reduced oxidative damage in a dose-dependent manner as evidenced by a range of biochemical analysis and immunoblotting study. Moreover, it induced the protein and mRNA expression of HO-1 together with its upstream mediator Nrf2 and activated the phosphorylation of AKT in HepG2 cells. LY294002, a PI3K/AKT inhibitor, significantly suppressed the Nrf2 nuclear translocation and HO-1 expression in H₂ O₂ induced HepG2 cells treated with Swi. In addition, RNA interference with Nrf2 significantly reduced the expression level of Nrf2 and HO-1 in the nucleus. Swi has a significant protective effect on cell damage in H₂ O₂ induced HepG2 cells by increasing the antioxidant capacity which is achieved through the AKT/Nrf2/HO-1 pathway. Additionally, in vivo, Swi could protect the liver of type 2 diabetic mice by improving lipid deposition in liver tissue and inhibiting oxidative stress. These findings indicated that Swi can be a promising dietary agent to improve type 2 diabetes.

PDX-1: A Promising Therapeutic Target to Reverse Diabetes

The pancreatic duodenum homeobox-1 (PDX-1) is a transcription factor encoded by a Hox-like homeodomain gene that plays a crucial role in pancreatic development, β-cell differentiation, and the maintenance of mature β-cell functions. Research on the relationship between PDX-1 and diabetes has gained much attention because of the increasing prevalence of diabetes melitus (DM). Recent studies have shown that the overexpression of PDX-1 regulates pancreatic development and promotes β-cell differentiation and insulin secretion. It also plays a vital role in cell remodeling, gene editing, and drug development. Conversely, the absence of PDX-1 increases susceptibility to DM. Therefore, in this review, we summarized the role of PDX-1 in pancreatic development and the pathogenesis of DM. A better understanding of PDX-1 will deepen our knowledge of the pathophysiology of DM and provide a scientific basis for exploring PDX-1 as a potential target for treating diabetes.