Extraction of Flavonoids from the Flowers of Abelmoschus manihot (L.) Medic by Modified Supercritical CO₂ Extraction and Determination of Antioxidant and Anti-Adipogenic Activity

Exploring the role of NLRP3 inflammasome in diabetic nephropathy and the advancements in herbal therapeutics

Diabetic nephropathy (DN), a prevalent complication of diabetes mellitus (DM), is clinically marked by progressive proteinuria and a decline in glomerular filtration rate. The etiology and pathogenesis of DN encompass a spectrum of factors, including hemodynamic alterations, inflammation, and oxidative stress, yet remain incompletely understood. The NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome, a critical component of the body's innate immunity, plays a pivotal role in the pathophysiology of DN by promoting the release of inflammatory cytokines, thus contributing to the progression of this chronic inflammatory condition. Recent studies highlight the involvement of the NLRP3 inflammasome in the renal pathology associated with DN. This article delves into the activation pathways of the NLRP3 inflammasome and its pathogenic implications in DN. Additionally, it reviews the therapeutic potential of traditional Chinese medicine (TCM) in modulating the NLRP3 inflammasome, aiming to provide comprehensive insights into the pathogenesis of DN and the current advancements in TCM interventions targeting NLRP3 inflammatory vesicles. Such insights are expected to lay the groundwork for further exploration into TCM-based treatments for DN.

Hibifolin protected pro-inflammatory response and oxidative stress in LPS-induced acute lung injury through antioxidative enzymes and the AMPK2/Nrf-2 pathway

ALI is a grave medical ailment that manifests as abrupt inflammation of the lungs and diminished oxygen levels. It poses a considerable challenge to the medical fraternity, with elevated rates of morbidity and mortality. Our research endeavors to investigate the potential of hibifolin, a flavonoid glucuronide, imbued with potent antioxidant properties, and its molecular mechanism to combat LPS-induced ALI in mice. The study utilized ICR mice to create an ALI model induced by LPS. Prior to LPS administration, hibifolin was given at 10, 30, or 50 mg/kg, or dexamethasone was given at 1 mg/kg to assess its preventative impact. Changes in lung tissue, pulmonary edema, and lipid peroxidation were analyzed using H&E stain assay, lung wet/dry ratio assay, and MDA formation assay, respectively. Activity assay kits were used to measure MPO activity and antioxidative enzymes (SOD, CAT, GPx) activity in the lungs. Western blot assay was used to determine the phosphorylation of Nrf-2 and AMPK2 in the lungs. Hibifolin demonstrated a concentration-dependent improvement in LPS-induced histopathologic pulmonary changes. This treatment notably mitigated pulmonary edema, lipid peroxidation, and MPO activity in ALI mice. Additionally, hibifolin successfully restored antioxidative enzyme activity in the lungs of ALI mice. Moreover, hibifolin effectively promoted Nrf-2 phosphorylation and reinstated AMPK2 phosphorylation in the lungs of ALI mice. The results indicate that hibifolin could effectively alleviate the pathophysiological impact of LPS-induced ALI. This is likely due to its antioxidative properties, which help to restore antioxidative enzyme activity and activate the AMPK2/Nrf2 pathway. These findings are valuable in terms of enhancing our knowledge of ALI treatment and pave the way for further investigation into hibifolin as a potential therapeutic option for lung injuries.

Effects of okra (Abelmoschus esculentus L.) leaves, fruits and seeds extracts on European sea bass (Dicentrarchus labrax) leukocytes, and their cytotoxic, bactericidal and antioxidant properties

Okra, Abelmoschus esculentus L., is a popular vegetable crop with many bioactive compounds. The in vitro immunostimulant, cytotoxic, bactericidal and antioxidant activities of ethanolic extracts obtained from different parts of okra (leaves, fruits, and seeds) were studied. Phytochemical screening of hydroalcoholic extracts of okra leaves, fruits and seeds revealed a significant content of total phenols and flavonoids. Significant effects on the activities of leukocytes in the head kidney of European sea bass (Dicentrarchus labrax) (viability, phagocytic ability and capacity, and respiratory burst), as well as on peroxidase leukocyte contents were detected after incubation for 24 h with different concentrations (0.01-1 mg mL^-1) of the extracts. The mean concentrations (0.1 and 0.5 mg mL^-1) of the different extracts increased the phagocytic ability and respiratory activity of head kidney leukocytes. However, the mean concentrations (0.1 mg mL^-1) of leaf and fruit extracts significantly decreased the peroxidase activity of leukocytes. In addition, all ethanolic okra extracts at higher concentrations (1 mg mL^-1) produced a marked reduction in the viability of the DLB-1 cell line compared to the viability recorded in the control samples. In addition, ethanolic extracts used at 0.5 and 1 mg mL^-1 had a significant cytotoxic effect on the viability of PLHC-1 cells. Finally, all doses of seed and leaf extracts at higher concentrations (0.5 and 1 mg mL^-1) showed significant bactericidal activity on two fish pathogenic bacteria, Vibrio anguillarum and V. harveyi strains. Finally, a remarkable antioxidant activity was detected on the ethanolic extracts. All these results point to their possible use as an alternative to chemical compounds in farmed fish.

Quercetin improves contrast-induced acute kidney injury through the HIF-1α/lncRNA NEAT1/HMGB1 pathway

CONTEXT

The risk of contrast-induced acute kidney injury (CI-AKI) is increasing and the harm is great. Quercetin is the main active component in Abelmoschus manihot (L.) Medik (Malvaceae) and was reported to reduce the expression of HIF-1α.

OBJECTIVE

We investigate whether quercetin improves the CI-AKI through the HIF-1α/lncRNA NEAT1/HMGB1 pathway.

MATERIALS AND METHODS

HK-2 cells were treated with iohexol (200 mg/mL) for 6 h to establish a CI-AKI model. Quercetin (20 μM) was administered to CI-AKI cells cultured in dishes for 24 h. Cell morphology was observed by a fluorescence microscope. MTT and TUNEL assays were used to detect cell survival rate and apoptosis. Relative mRNA levels were measured by qRT-PCR. Protein levels were detected using western blotting. IL-6 and TNF-α protein levels were tested by Elisa assay. Targeting binding sites of HIF-1α and lncRNA NEAT1 were detected by luciferase assay.

RESULTS

The IC₅₀ value of quercetin was 163.25 μM. The expression levels of HIF-1α, lncRNA NEAT1 and HMGB1 were upregulated in the CI-AKI cell model. Quercetin diminished cell injury and apoptosis via inhibiting HIF-1α. Silencing of HIF-1α targeting lncRNA MEAT1 diminished cell injury and apoptosis. Silencing lncRNA NEAT1 has the same effect via suppressing HMGB1 expression. Collectively, quercetin diminished cell injury and apoptosis in CI-AKI cell model via the inhibition of HIF-1α on lncRNA NEAT1/HMGB1 signalling pathway.

DISCUSSION AND CONCLUSIONS

Quercetin diminished cell injury and apoptosis in CI-AKI cell mode via the inhibition of HIF-1α on the lncRNA NEAT1/HMGB1 signalling pathway, offering a potential novel therapeutic target for CI-AKI therapy.

Carbon dioxide expanded liquid: an effective solvent for the extraction of quercetin from South African medicinal plants

BACKGROUND

Quercetin is one of the most important bioflavonoids having positive effects on the biological processes and human health. Typically, it is extracted from plant matrices using conventional methods such as maceration, sonication, infusion, and Soxhlet extraction with high solvent consumption. Our study aimed to optimize the environmentally friendly carbon dioxide-based method for the extraction of quercetin from quince fruit with an emphasis on extraction yield, repeatability, and short extraction time.

RESULTS

A two-step design of experiments was used for the optimization of the key parameters affecting physicochemical properties, including CO₂/co-solvent ratio, co-solvent type, temperature, and pressure. Finally, gas expanded liquid combining CO₂/ethanol/H₂O in a ratio of 10/81/9 (v/v/v) provided the best extraction yield. Extraction temperature 66 °C and pressure 22.3 MPa were the most suitable conditions after careful optimization, although both parameters did not significantly affect the process. It was confirmed by experiments in various pressure and temperature conditions and statistical comparison of obtained data. The optimized extraction procedure at a flow rate of 3 mL/min took 30 min. The repeatability of the extraction method exhibited an RSD of 20.8%.

CONCLUSIONS

The optimized procedure enabled very fast extraction in 30 min using environmentally friendly solvents and it was successfully applied to 16 different plant samples, including 14 bulbs and 2 fruits from South Africa. The quercetin content in extracts was quantified using ultra-high performance liquid chromatography (UHPLC) with tandem mass spectrometry. UHPLC hyphenated with high-resolution mass spectrometry was used to confirm chemical identity of quercetin in the analyzed samples. We quantified quercetin in 11 samples of all 16 tested plants. The quercetin was found in Agapanthus praecox from the Amaryllidaceae family and its presence in this specie was reported for the first time.

Review on the “Biological Applications of Okra Polysaccharides and Prospective Research”

Background

Vegetables with edible parts like flowers, fruits, stems, leaves, fibers, roots, and seeds are rich sources of essential vitamins, minerals, and trace elements with various medical functions. Many diseases such as osteoporosis, diabetes, high cholesterol, obesity, heart diseases, and stroke are caused by poor, healthy lifestyle or nutrition. Therefore, generation of new biological functions from vegetables will increase the interests of scientific research and applications.

Main body

Okra is an edible vegetable which contains vitamins, fiber, carbohydrates, protein, and minerals. The bioactive compounds of okra possess various biological activities such as anti-inflammation, antibacterial, anticancer, and antifungal. Polysaccharides from vegetables or medicinal plants are important large molecules with various biological applications. In this review, we will focus on the biological properties and nanoparticle uses of polysaccharides isolated from okra and the extraction methods of polysaccharides.

Conclusion

This review will enhance the scientific research findings of okra polysaccharides and recommend future prospective of polysaccharides for biological uses.

Traditional Uses, Chemical Constituents, Biological Properties, Clinical Settings, and Toxicities of Abelmoschus manihot L.: A Comprehensive Review

Abelmoschus manihot, an annual herbal flowering plant, is widely distributed throughout eastern Europe and in temperate and subtropical regions of Asia. Its flowers have been traditionally used for the treatment of chronic kidney disease in China. Currently, more than 128 phytochemical ingredients have been obtained and identified from the flowers, seeds, stems, and leaves of A. manihot. The primary components are flavonoids, amino acids, nucleosides, polysaccharides, organic acids, steroids, and volatile oils. A. manihot and its bioactive constituents possess a plethora of biological properties, including antidiabetic nephropathy, antioxidant, antiadipogenic, anti-inflammatory, analgesic, anticonvulsant, antidepressant, antiviral, antitumor, cardioprotective, antiplatelet, neuroprotective, immunomodulatory, and hepatoprotective activities, and have effects on cerebral infarction, bone loss, etc. However, insufficient utilization and excessive waste have already led to a rapid reduction of resources, meaning that a study on the sustainable use of A. manihot is urgent and necessary. Moreover, the major biologically active constituents and the mechanisms of action of the flowers have yet to be elucidated. The present paper provides an early and comprehensive review of the traditional uses, chemical constituents, pharmacological activities, and pharmaceutical, quality control, toxicological, and clinical settings to emphasize the benefits of this plant and lays a solid foundation for further development of A. manihot.

Environmentally Friendly Methods for Flavonoid Extraction from Plant Material: Impact of Their Operating Conditions on Yield and Antioxidant Properties

The flavonoids are compounds synthesized by plants, and they have properties such as antioxidant, anticancer, anti-inflammatory, and antibacterial, among others. One of the most important bioactive properties of flavonoids is their antioxidant effect. Synthetic antioxidants have side toxic effects whilst natural antioxidants, such as flavonoids from natural sources, have relatively low toxicity. Therefore, it is important to incorporate flavonoids derived from natural sources in several products such as foods, cosmetics, and drugs. For this reason, there is currently a need to extract flavonoids from plant resources. In this review are described the most important parameters involved in the extraction of flavonoids by unconventional methods such as ultrasound, pressurized liquid extraction, mechanochemical, high hydrostatic pressure, supercritical fluid, negative pressure cavitation, intensification of vaporization by decompression to the vacuum, microwave, infrared, pulsed electric field, high-voltage electrical discharges, and enzyme-assisted extraction. There are no unified operation conditions to achieve high yields and purity. Notwithstanding, progress has been achieved in the development of more advanced and environmentally friendly methods of extraction. Although in literature are found important advances, a complete understanding of the extraction process in each of the unconventional techniques is needed to determine the thermodynamic and kinetic mechanisms that govern each of the techniques.

The Flower Extract of Abelmoschus manihot (Linn.) Increases Cyclin D1 Expression and Activates Cell Proliferation

Abelmoschus manihot (Linn.) is a medicinal herbal plant that is commonly used to treat chronic kidney disease and hepatitis. However, its effect on cell proliferation has not been clearly revealed. In this report, we sought to determine the effect of the flower extract of A. manihot (FA) on cell proliferation. Based on our findings, FA increased the proliferation of human diploid fibroblast (HDF) and HEK293 cells. Through cell cycle analysis, FA was found to increase the number of HDF cells in the S phase and G2/M phase. FA also increased the expression of cyclin D1 and enhanced the migration of HDF cells. By administering FA to HDF cells with ≥30 passages, a decrease in the number of senescence-associated β galactosidase-positive cells was observed, thereby indicating that FA can ameliorate cellular senescence. Collectively, our findings indicate that FA increases cyclin D1 expression and regulates cell proliferation.

Therapeutic Effect of Abelmoschus manihot on Type 2 Diabetic Nonproliferative Retinopathy and the Involvement of VEGF

Objective

To evaluate the efficacy of Abelmoschus manihot in treating type 2 diabetic nonproliferative retinopathy.

Methods

It was a randomized controlled clinical trial. The recruited eighty subjects with type 2 diabetic nonproliferative retinopathy were randomly divided into treatment group and control group. The two groups received basic treatments including control of blood glucose, blood pressure and blood lipid, management of diet, exercise and health education, and monitoring of relevant indicators. Additionally, the treatment group was given oral administration of Abelmoschus manihot. All subjects were followed up on monthly basis for consecutive six months. The related parameters including diabetic retinopathy (DR) incidence rates, “Early Treatment Diabetic Retinopathy Study” (ETDRS) vision scores, retinal thicknesses in macular region, serum vascular endothelial growth factor (VEGF) levels, and biochemical indicators of both groups before and after treatment were accurately collected and statistically analyzed.

Results

There were no significant differences of DR severity levels, ETDRS vision scores, macular retinal thicknesses such as cube average thickness (CAT), central subfield thickness (CST), and cube volume (CV), and serum VEGF levels between two groups before treatment. Meanwhile, there were no significant differences of demographic characteristics, case terminations, blood glucose, blood lipid, blood pressure, biochemical indicators of hepatorenal function, hypoglycemic drugs, hypotensive drugs, and other basic treatments between two groups during six months treatment. The present study suggested that the remission rate of DR and the ETDRS vision score in the treatment group were significantly higher than those of the control group (remission rate: 25.4% vs 9.3%, P=0.01; ETDRS score: 78 (72, 82) vs 72 (67, 80), P=0.0002) while the progression rate of DR in the treatment group was significantly lower than that of the control group (progression rate: 4.2% vs 18.7%, P=0.007) after six months treatment. In addition, the CAT, CST, CV, and serum VEGF levels of the treatment group were significantly improved after the treatment (CAT: 286 (278, 302) vs 282 (270, 295) μm, P < 0.0001; CST: 251 (239, 274) vs 248 (235, 265) μm, P < 0.0001; CV: 10.3 (10.0, 10.9) vs 10.1 (9.7, 10.6) mm³, P < 0.0001; VEGF: 0.21 (0.14, 0.58) vs 0.16 (0.10, 0.23) ng/ml, P=0.0026), while there were no significant differences of the control group before and after treatment (CAT: 287 (279, 294) vs 287 (279, 295) μm, P=0.27; CST: 250 (240, 266) vs 252 (238, 266) μm, P=0.72; CV: 10.4 (10.1, 10.6) vs 10.4 (10.1, 10.7) mm³, P=0.53; VEGF: 0.21 (0.13, 0.66) vs 0.23 (0.12, 0.64) ng/ml, P=0.85).

Conclusion

The study offered the novel evidence for the therapeutic effect of Abelmoschus manihot on type 2 diabetic nonproliferative retinopathy, which was associated with improved VEGF. This trial is registered with ChiCTR1800019292.

Huangkui Lianchang Decoction Ameliorates DSS-Induced Ulcerative Colitis in Mice by Inhibiting the NF-kappaB Signaling Pathway

BACKGROUND

The nuclear factor kappa beta (NF-κB) signaling pathway plays an important role in ulcerative colitis (UC). Huangkui Lianchang decoction (HLD) is an effective traditional Chinese medicinal compound used in the treatment of UC. HLD has good effects in the clinic, but the mechanism by which HLD acts is unclear. This study aims to reveal the exact molecular mechanism of HLD in the treatment of UC.

METHODS

Mouse ulcerative colitis was induced by dextran sulfate sodium (DSS) and treated with HLD. Intestinal damage was assessed by disease activity index (DAI), colon macroscopic lesion scores, and histological scores. Interleukin (IL)-6, tumor necrosis factor (TNF)-α, and IL-1β were detected in colon tissue using ELISA. Myeloperoxidase (MPO) and superoxide dismutase (SOD) activities in the colonic mucosa were measured. The levels of IL-6, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) in the colon were determined by real-time quantitative polymerase chain reaction (qPCR). The expression of NF-κB, IκBα, and p-IκBα in the colon was measured by Western blot.

RESULTS

After treatment with HLD, the DAI scores, macroscopic lesion scores, and histological scores decreased, and the levels of inflammatory cytokines related to the NF-κB signaling pathway, such as IL-6, TNF-α, and IL-1β, as well as those of iNOS and COX-2, were reduced; at the same time, colonic pathological damage was alleviated, and the MPO and SOD activities decreased. Western blot confirmed that HLD can inhibit the NF-κB signaling pathway in DSS-induced ulcerative colitis.

CONCLUSION

HLD can alleviate the inflammation caused by ulcerative colitis. In particular, high doses of HLD can significantly alleviate intestinal inflammation and have comparable efficacy to Mesalazine. We propose that the anti-inflammatory activity of HLD on DSS-induced colitis in mice may involve the inhibition of the NF-κB pathway.

Enrichment and Purification of the Bioactive Flavonoids from Flower of Abelmoschus manihot (L.) Medic Using Macroporous Resins

Flower of Abelmoschus manihot (FAM) is clinically effective to treat chronic kidney disease (CKD) with a relatively high dosage. To improve the efficacy and the compliance of patients, macroporous resins were adopted to enrich and purify flavonoids from FAM, which are thought to be the major renal protective constituents in FAM. After screening six different kinds of macroporous resins, HPD-100 was selected for its great adsorption and desorption capacity. Then, orthogonal design tests were used to optimize parameters in the processes of impurity removal and flavonoids of FAM desorption on column chromatogram. Moreover, process scale-up was performed, and purification effects maintained after amplification. After purification, the content of seven main flavonoids in the product increased from 8.29% to 51.43%. Protective and anti-inflammatory effects of crude extract and the flavonoid component of FAM after purification were investigated on the adriamycin-damaged HK-2 cells and lipopolysaccharide-stimulated Raw 264.7 cells models. Both bioactivities were improved greatly after purification for these two cell models. Therefore, the purification process had enriched the main bioactive constituents with potential alleviating kidney injury activities. The flavonoid component of FAM is worthy of being developed as an improved remedy for CKD with better patients' compliance.