Discovering inhibitor molecules for pathological crystallization of CaOx kidney stones from natural extracts of medical herbs

Streamlined strategy for discovering active compounds for nephrolithiasis treatment from herbal medicines using the fruit fly model

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicines (TCMs) show promise for treating nephrolithiasis (kidney stones) with fewer adverse effects. However, identifying the key active compounds and understanding the therapeutic mechanisms of these herbs is challenging due to their complex compositions. Utilizing appropriate animal models is essential for overcoming this challenge and investigating the underlying mechanisms.

AIM OF THE STUDY

This study aims to establish a rapid discovery strategy to identify novel active components from TCMs using a Drosophila melanogaster (fruit fly) model.

MATERIALS AND METHODS

A discovery strategy for novel active components from candidate TCMs for the treatment of kidney stones was established using a fruit fly kidney stone model. The model was developed by feeding flies sodium oxalate (NaOx) to induce crystallization in their Malpighian tubules (MTs). Water extracts from various TCMs were screened for their efficacy against kidney stones. Effective extracts were then fractionated using solid-phase extraction and re-evaluated with the fruit fly model. These effective fractions were further analyzed using LC-MS and NMR to identify their compositions, and the identified compounds underwent additional testing with the fruit fly model to pinpoint the core active compounds. DHE staining, RT-qPCR, and in vitro crystallization assays were employed to explore the therapeutic mechanisms of both the effective TCM extracts and their core compounds, ensuring consistency in their mechanisms within the fly model. Finally, the efficacy of the core compounds was validated in a glyoxalate-induced mouse model.

RESULTS

In this study, a calcium oxalate kidney stone model was established using fruit fly. Three TCMs-Honghua (HH), Danshen (DS), and Huangqi (HQ)-were identified for their therapeutic effects against kidney stones from 15 candidates using the fruit fly model. The core compounds discovered were Hydroxysafflower yellow A (HYA) from HH, Salvianic acid A (SAA) from DS, and Calycosin-7-O-β-D-glucoside (CG) from HQ. HYA, SAA, and CG all demonstrated efficacy by inhibiting crystallization and reducing oxidative stress. Additionally, CG was also found to increase diuresis. The therapeutic effects of HYA, SAA, and CG were further validated in the mouse model.

CONCLUSION

We developed an efficient strategy for identifying core components of TCMs for kidney stones treatment using a fruit fly model combined with chemical isolation and identification techniques. This approach led to the discovery of three novel potential compounds for controlling kidney stones. Validated in mammalian models, these findings underscore the fruit fly model's utility in uncovering bioactive substances from TCMs, laying the groundwork for future research and the development of novel kidney stones therapies.

Bioguided isolation of anti-inflammatory and anti-urolithiatic active compounds from the decoction of Cissus gongylodes leaves

ETHNOPHARMACOLOGICAL RELEVANCE

The Cissus gongylodes has traditionally been used in the diet of indigenous people in Brazil and in traditional medicine for kidney stone removal and inflammatory diseases. The active compounds responsible for these pharmacological activities are unknown.

AIM OF THE STUDY

This study aims to isolate, for the first time, the compounds in the decoction of C. gongylodes leaves responsible for their anti-inflammatory and anti-urolithiatic ethnopharmacological properties.

MATERIALS AND METHODS

The most active fractions of the C. gongylodes leaf decoction were fractionated using SPE-C18 and the compounds were purified through HPLC-UV-DAD. The decoction fractions and isolated compounds were evaluated for their anti-inflammatory and anti-urolithiatic activities. The anti-inflammatory activity was assessed using an ex vivo assay in human blood induced by LPS and calcium ionophore, measuring inflammatory mediators, PGE2 and LTB4. The anti-urolithiatic activity was evaluated using an in vitro experimental model with human urine to determine the dissolution of the most recurrent calcium oxalate (CaOx) crystals. Additionally, the decoction was chemically characterized through metabolomic analysis using UHPLC-ESI-HRMS.

RESULTS

The isolated compounds from the decoction of C. gongylodes, including rutin, eriodictyol 3'-O-glycoside, and isoquercetin, have demonstrated significant multi-target actions. These components act as anti-inflammatory agents by inhibiting the release of main inflammatory mediators, PGE2 and LTB4. Additionally, they exhibit anti-urolithiatic properties, promoting the dissolution of calcium oxalate (CaOx) crystals. Furthermore, the characterization of the decoction by UHPLC-ESI-HRMS revealed a high content of flavonoids, mainly glycosylated flavonoids.

CONCLUSIONS

The results support the traditional use of C. gongylodes decoction, identifying the compounds responsible for its anti-inflammatory and anti-urolithiatic effects. The decoction fractions and isolated compounds exhibited dual anti-inflammatory activity, effectively inhibiting key inflammatory pathways and potentially presenting fewer adverse effects while also promoting the dissolution of CaOx crystals associated with urolithiasis. The multi-target action displayed by C. gongylodes is particularly desirable in the treatment of urolithiasis, as inflammation and PGE2 production precede and contribute to the formation of CaOx crystals in the kidneys. Based on these actions, C. gongylodes emerges as a potent source of active compounds for the development of new treatments for urolithiasis.

Research landscape and pharmacological mechanisms of traditional Chinese medicines in treating and preventing urolithiasis: Unearthing an anti-urolithic treasure trove

ETHNOPHARMACOLOGICAL RELEVANCE

Urolithiasis represents a predominant concern within urology due to its high recurrence rate and consequential surgical complications. Traditional Chinese Medicine (TCM), with a history spanning over 2000 years in treating kidney diseases, not only offers a less invasive and cost-effective option for treating and preventing urolithiasis, but also serves as a pharmacological treasure trove for the development of anti-urolithic drugs.

AIM OF THE STUDY

With the continuous deepening of research on the anti-urolithic effects of Chinese medicines, the pharmacological mechanisms of TCMs against urolithiasis are continuously evolving. Therefore, it is essential to summarize the current research status, clinical effectiveness, and mechanisms of TCM in treating and preventing urolithiasis, to ascertain its potential in anti-urolithic treatments, and to provide a reference for future anti-urolithiasis drug research.

METHODS

The electronic databases such as PubMed, Web of Science, and China National Knowledge Infrastructure (CNKI) have been utilized to retrieve relevant literature spanning from 2000 to September 2023, using keywords "Traditional Chinese Medicine" and "Urolithiasis". Then we conducted a visual analysis of the current status of related research, as well as a systematic organization of the therapeutic effects and underlying mechanisms of anti-urolithic TCMs.

RESULTS

Through the organization of research models, therapeutic effects, and active ingredients of 31 potential anti-urolithic TCMs, we have systematically summarized the underlying mechanisms of TCMs in management of urolithiasis. Mechanistically, Chinese herbs facilitate stone expulsion by enhancing diuresis, instigating anti-spasmodic effects, and promoting ureteral peristalsis when addressing calculi. They also harbor the potential to dissolve pre-existing stones. In terms of stone recurrence prevention, TCM compounds obstruct stone formation through targeting the sequence of crystal adhesion, nucleation, growth, and aggregation to inhibit stone formation. Additionally, TCM's significant roles include stifling oxidative stress, augmenting urinary stone inhibitors, and harmonizing oxalate metabolism, all of which are critical actions in stone prevention.

CONCLUSION

The anti-urolithic mechanism of TCM is multifaceted. Investigating the anti-urolithiasis mechanisms of TCM not only illuminates the potential of Chinese medicine in treating and preventing urolithiasis, but also uncovers active molecules and targets for drug treatment against calculus formation.

New insight into oxidative stress and inflammatory responses to kidney stones: Potential therapeutic strategies with natural active ingredients

Kidney stones, a prevalent urological disorder, are closely associated with oxidative stress (OS) and the inflammatory response. Recent research in the field of kidney stone treatment has indicated the potential of natural active ingredients to modulate OS targets and the inflammatory response in kidney stones. Oxidative stress can occur through various pathways, increasing the risk of stone formation, while the inflammatory response generated during kidney stone formation further exacerbates OS, forming a detrimental cycle. Both antioxidant systems related to OS and inflammatory mediators associated with inflammation play roles in the pathogenesis of kidney stones. Natural active ingredients, abundant in resources and possessing antioxidative and anti-inflammatory properties, have the ability to decrease the risk of stone formation and improve prognosis by reducing OS and suppressing pro-inflammatory cytokine expression or pathways. Currently, numerous developed natural active ingredients have been clinically applied and demonstrated satisfactory therapeutic efficacy. This review aims to provide novel insights into OS and inflammation targets in kidney stones as well as summarize research progress on potential therapeutic strategies involving natural active ingredients. Future studies should delve deeper into exploring efficacy and mechanisms of action of diverse natural active ingredients, proposing innovative treatment strategies for kidney stones, and continuously uncovering their potential applications.

Targeting urinary calcium oxalate crystallization with inulin-type AOFOS from Aspidopterys obcordata Hemsl. for the management of rat urolithiasis

ETHNOPHARMACOLOGICAL RELEVANCE

Calcium oxalate crystals play a key role in the development and recurrence of kidney stones (also known as urolithiasis); thus, inhibiting the formation of these crystals is a central focus of urolithiasis prevention and treatment. Previously, we reported the noteworthy in vitro inhibitory effects of Aspidopterys obcordata fructo oligosaccharide (AOFOS), an active polysaccharide of the traditional Dai medicine Aspidopterys obcordata Hemsl. (commonly known as Hei Gai Guan), on the growth of calcium oxalate crystals.

AIM OF THE STUDY

To investigated the effectiveness and mechanism of AOFOS in treating kidney stones.

MATERIALS AND METHODS

A kidney stones rats model was developed, followed by examining AOFOS transport dynamics and effectiveness in live rats. Additionally, a correlation between the polysaccharide and calcium oxalate crystals was studied by combining crystallization experiments with density functional theory calculations.

RESULTS

The results showed that the polysaccharide was transported to the urinary system. Furthermore, their accumulation was inhibited by controlling their crystallization and modulating calcium ion and oxalate properties in the urine. Consequently, this approach helped effectively prevent kidney stone formation in the rats.

CONCLUSIONS

The present study emphasized the role of the polysaccharide AOFOS in modulating crystal properties and controlling crystal growth, providing valuable insights into their potential therapeutic use in managing kidney stone formation.

The anti-urolithiasis activity and safety of strangury-relieving herbs: A comparative study based on fruit fly kidney stone model

ETHNOPHARMACOLOGICAL RELEVANCE

Urolithiasis is one of the oldest and most widespread urological diseases suffered globally. In the long history of Traditional Chinese Medicine, there're numerous herbs documented with strangury-relieving properties playing crucial roles in treating various urological disorders, including dysuria, hematuria, and renal colic, etc., which may be caused by urolithiasis. Exploring these herbs may reveal safer, more effective, and cost-efficient drugs and therapies for urolithiasis.

AIM OF THE STUDY

This study aims to assess the anti-urolithiasis efficacy and safety of 46 Chinese traditional and folk herbal drugs using the fruit fly (Drosophila melanogaster) kidney stone model, in order to identify the most valuable ethnomedicinal materials.

MATERIALS AND METHODS

Water extract and 50% ethanol extract of each herb were prepared respectively. 0.2% (w/w) sodium oxalate was chosen as appropriate lithogenic agent through fruit fly life span study. Male fruit-flies within three days of emergence were aged for an additional three days, then were randomly divided into experimental groups, model group and control groups (n = 20). The flies in blank control group, model group and positive control group were fed with standard food, standard food containing 0.2% sodium oxalate, standard food containing 0.2% sodium oxalate and 3% (w/w) Garcinia cambogia extract, respectively. Meanwhile, flies in the experimental groups were raised on standard food containing 0.2% sodium oxalate and 3% (w/w) herbal extract. The anti-urolithiasis capability of the extracts was evaluated using stone area ratio (the stone area divided by the area of the Malpighian tubule) and stone-clearing rate. Additionally, the 7-day mortality rate was employed as an indicator of safety.

RESULTS

Out of the 46 herbs, 24 exhibited significant anti-urolithiasis effects in their water extracts. Among them, Herba Nephrolepidis, Herba Humuli, Herba Desmodii Styracifolii, Cortex Plumeriae Rubrae, and Herba Mimosae Pudicae showed us a low 7-day mortality rate of fruit-flies as well. However, only a limited number of herbal extracts (8 out of 46) showed obvious anti-urolithiasis activity in their 50% ethanol extracts.

CONCLUSION

Highly potential anti-urolithiasis candidates were discovered from strangury-relieving herbs recorded in classical Traditional Chinese Medicine works, highlighting the significant value of traditional and folk ethnopharmacological knowledge.

Understanding formation processes of calcareous nephrolithiasis in renal interstitium and tubule lumen

Kidney stone, one of the oldest known diseases, has plagued humans for centuries, consistently imposing a heavy burden on patients and healthcare systems worldwide due to their high incidence and recurrence rates. Advancements in endoscopy, imaging, genetics, molecular biology and bioinformatics have led to a deeper and more comprehensive understanding of the mechanism behind nephrolithiasis. Kidney stone formation is a complex, multi-step and long-term process involving the transformation of stone-forming salts from free ions into asymptomatic or symptomatic stones influenced by physical, chemical and biological factors. Among the various types of kidney stones observed in clinical practice, calcareous nephrolithiasis is currently the most common and exhibits the most intricate formation mechanism. Extensive research suggests that calcareous nephrolithiasis primarily originates from interstitial subepithelial calcified plaques and/or calcified blockages in the openings of collecting ducts. These calcified plaques and blockages eventually come into contact with urine in the renal pelvis, serving as a nidus for crystal formation and subsequent stone growth. Both pathways of stone formation share similar mechanisms, such as the drive of abnormal urine composition, involvement of oxidative stress and inflammation, and an imbalance of stone inhibitors and promoters. However, they also possess unique characteristics. Hence, this review aims to provide detailed description and present recent discoveries regarding the formation processes of calcareous nephrolithiasis from two distinct birthplaces: renal interstitium and tubule lumen.

Molecular mechanism of Rhizoma Polygonati in the treatment of nephrolithiasis: network pharmacology analysis and in vivo experimental verification

Rhizoma Polygonati (RP) is the dried rhizome of the liliaceous plant. It has anti-inflammatory and anti-apoptosis effects. But its role in kidney stones has not been studied. The purpose of this study was to verify the effect of RP in the treatment of nephrolithiasis through network pharmacological analysis and in vivo experiments. The active compounds and protein targets of RP, as well as the potential targets of the nephrolithiasis were searched from the database. The protein-protein interaction (PPI) network diagram and the drug-compounds-targets-disease network were constructed. The enrichment analysis was performed by Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG). Subsequently, the effect of RP on the prevention and treatment of nephrolithiasis was experimentally validated in vivo. Animal experiments showed that RP ameliorates renal function and reduced crystal deposition in a mouse model. It may act through anti-inflammation and anti-apoptosis. Our study showed that RP could prevent and treat nephrolithiasis by inhibiting apoptosis and inflammation, which provided a new efficacy and clinical application for RP.

Unlocking New Approaches to Urolithiasis Management Via Nutraceuticals

Urolithiasis, commonly known as kidney stones, is characterized by the formation of hard deposits in the urinary tract. These stones can cause severe pain and discomfort, and their management typically involves a combination of medical interventions and lifestyle modifications. According to the literature, 30% and 50% of urolithiasis cases recur. Between 9 and 12% of persons in industrialised countries are predicted to have urolithiasis at some time. Due to the high frequency of stone formation, recurrent nature, and prevalence in adults, it has a significant impact on society, the person, and the health care system. Adopting the best prophylactic measures is crucial in light of these developments to decrease the impact of urolithiasis on individuals and society. In recent years, there has been growing interest in the potential role of nutraceuticals in the management of urolithiasis. Nutraceuticals, such as herbal extracts, vitamins, minerals, and probiotics, have gained recognition for their potential in promoting urinary health and reducing the risk of urolithiasis. These compounds can aid in various ways, including inhibiting crystal formation, enhancing urine pH balance, reducing urinary calcium excretion, and supporting kidney function. Additionally, nutraceuticals can help alleviate symptoms associated with urolithiasis, such as pain and inflammation. While medical interventions remain crucial, incorporating nutraceuticals into a comprehensive management plan can offer a holistic approach to urolithiasis, improving patient outcomes and quality of life. Therefore, nutraceuticals may be a desirable choice for treating and avoiding recurring urolithiasis for patients and medical professionals. Therefore, the present study has focused on nutraceuticals' role in preventing urolithiasis.

A Mechanistic Insight into Beneficial Effects of Polyphenols in the Prevention and Treatment of Nephrolithiasis: Evidence from Recent In Vitro Studies

Nephrolithiasis is a pathological condition characterized by the formation of solid crystals in the kidneys or other parts of urinary tract. Kidney stones are a serious public health issue and financial burden for health care system, as well as a painful and uncomfortable condition for patients, resulting in renal tissue injury in severe cases. Dietary habits, low fluid and high salt intake predominantly, contribute to the development of kidney stones. Current research suggests that polyphenols have a protective effect in the pathogenesis of kidney stones. Polyphenols are a group of naturally occurring compounds found in plant-based foods such as fruits, vegetables, tea, and coffee. In this review, we explore mechanisms underlying the beneficial effects of polyphenols, such as oxidative stress reduction and modulation of inflammatory pathways, in various in vitro models of nephrolithiasis. Additionally, certain polyphenols, such as catechins found in green tea, have been shown to inhibit the formation and growth of kidney stones in animal studies. This review highlights the antioxidant and anti-inflammatory effects, as well as the inhibition of crystal formation, as results of polyphenol treatment in vitro. Further research is required to determine the specific effects of polyphenols on kidney stone formation in humans; however, current knowledge implicates that incorporating a variety of polyphenol-rich foods into the diet may be a beneficial strategy for individuals at risk of developing nephrolithiasis.

Application of metabolomics in urolithiasis: the discovery and usage of succinate

Urinary stone is conceptualized as a chronic metabolic disorder punctuated by symptomatic stone events. It has been shown that the occurrence of calcium oxalate monohydrate (COM) during stone formation is regulated by crystal growth modifiers. Although crystallization inhibitors have been recognized as a therapeutic modality for decades, limited progress has been made in the discovery of effective modifiers to intervene with stone disease. In this study, we have used metabolomics technologies, a powerful approach to identify biomarkers by screening the urine components of the dynamic progression in a bladder stone model. By in-depth mining and analysis of metabolomics data, we have screened five differential metabolites. Through density functional theory studies and bulk crystallization, we found that three of them (salicyluric, gentisic acid and succinate) could effectively inhibit nucleation in vitro. We thereby assessed the impact of the inhibitors with an EG-induced rat model for kidney stones. Notably, succinate, a key player in the tricarboxylic acid cycle, could decrease kidney calcium deposition and injury in the model. Transcriptomic analysis further showed that the protective effect of succinate was mainly through anti-inflammation, inhibition of cell adhesion and osteogenic differentiation. These findings indicated that succinate may provide a new therapeutic option for urinary stones.

Gallic acid ameliorates calcium oxalate crystal-induced renal injury via upregulation of Nrf2/HO-1 in the mouse model of stone formation

BACKGROUND

High prevalence and reoccurrence rate of nephrolithiasis bring about serious socioeconomic and healthcare burden, necessitating the need of effective therapeutic agents. Previous study revealed that gallic acid (GAL) alters the nucleation pathway of calcium oxalate (CaOx). On the other hand, it appears protective role against oxidative injury. Whether GAL could protect against crystal-induced lesion in vivo, and its underlying mechanism is yet unsolved.

PURPOSE

This study aims to investigate the protective effects of GAL on the crystal-induced renal injury and its underlying mechanism in the mouse model of stone formation induced by glyoxylic acid.

STUDY DESIGN AND METHODS

The mouse model of stone formation was established via successive intraperitoneal injection of glyoxylate. Proximal tubular epithelial cell line HK-2 treated with calcium oxalate monohydrate (COM) was used as in vitro model. The protective role of GAL on nephrolithiasis was tested by determination of tubular injury, crystal deposition and adhesion, levels of inflammatory cytokines, macrophage infiltration and the redox status of kidney. In vitro, effect of GAL on the ROS level and oxidative tubular injury induced by COM were detected, as well as major antioxidant pathway Nrf2/HO-1.

RESULTS

Administration of GAL alleviates the renal deposition and adhesion of CaOx stone. Meanwhile, GAL ameliorates the inflammation and renal tubular injury. Level of intracellular ROS, osteopontin and CD44 are reduced, either in the mouse model of stone formation or in the COM-treated HK-2 cells after treatment of GAL. Mechanistically, GAL activates Nrf2/HO-1 pathway in HK-2 cells. Silencing Nrf2 abrogates the protective effect of GAL on the oxidative injury and adhesion of COM in HK-2 cells.

CONCLUSION

Taken together, our study demonstrates the protective effect of GAL on the deposition of kidney stone and consequent tubular injury. Induction of the antioxidant pathway Nrf2/HO-1 was found to decrease the level of ROS and oxidative injury, thus implying that GAL could be a potential therapeutic agent for the treatment of nephrolithiasis.

Screening out key compounds of Glechomae Herba for antiurolithic activity and quality control based on spectrum-effect relationships coupled with UPLC-QDA

Glechomae Herba (GH) has been widely used in the treatment of urolithiasis, especially kidney stones, in China and Southeast Asia. Pharmacological studies have suggested that the antioxidant property of GH contributes to its anticalculus effect. CaSR is one of the main locations of kidney stones, and the mechanism of action of CaSR inhibitors in the treatment of kidney stones is similar to that of GH. However, until now, the antiurolithic chemical compounds in GH and their interaction with CaSR remain unknown. In our study, we revealed the interaction between the active compounds in GH and the active compounds in CaSR inhibitors by using spectrum-effect relationship analysis, pharmacodynamics, and molecular docking techniques. The results showed ten common peaks from the fingerprints of GH extracts from different regions. Pharmacological experiments showed that GH could significantly treat renal tissue lesions. Chlorogenic acid (CA), rosmarinic acid (RA), P5, luteolin, apigenin, and P9 were screened after the analysis of spectrum-effect relationships. In vitro validation experiments showed that all the screened compounds had inhibitory effects on the development of kidney stones in our model. The molecular docking results showed that the above compounds could be docked with CaSR in a natural state, and the docking score was less than 7. This work constructs a general model for the combination of UPLC-QDA and antiurolithic drugs, studies the spectrum-effect relationship of GH, and provides a new possibility for the development of new antiurolithic drugs.

Trigonelline prevents kidney stone formation processes by inhibiting calcium oxalate crystallization, growth and crystal-cell adhesion, and downregulating crystal receptors

Trigonelline is the second most abundant bioactive alkaloid found in coffee. It is classified as a phytoestrogen with similar structure as of estradiol and exhibits an estrogenic effect. A previous study has reported that fenugreek seed extract rich with trigonelline can reduce renal crystal deposition in ethylene glycol-induced nephrolithiatic rats. However, direct evidence of such anti-lithogenic effects of trigonelline and underlying mechanisms have not previously been reported. Our study therefore addressed the protective effects and mechanisms of trigonelline against kidney stone-forming processes using crystallization, crystal growth, aggregation and crystal-cell adhesion assays. Also, proteomics was applied to identify changes in receptors for calcium oxalate monohydrate (COM), the most common stone-forming crystal, on apical membranes of trigonelline-treated renal tubular cells. The analyses revealed that trigonelline significantly reduced COM crystal size, number and mass during crystallization. Additionally, trigonelline dose-dependently inhibited crystal growth and crystal-cell adhesion, but did not affect crystal aggregation. Mass spectrometric protein identification showed the smaller number of COM crystal receptors on apical membranes of the trigonelline-treated cells. Western blotting confirmed the decreased levels of some of these crystal receptors by trigonelline. These data highlight the protective mechanisms of trigonelline against kidney stone development by inhibiting COM crystallization, crystal growth and crystal-cell adhesion via downregulation of the crystal receptors on apical membranes of renal tubular cells.