Anti-Planktonic and Anti-Biofilm Properties of Pentacyclic Triterpenes-Asiatic Acid and Ursolic Acid as Promising Antibacterial Future Pharmaceuticals

Asiatic acid and its derivatives: Pharmacological insights and applications

Centella asiatica (L.) Urban has been utilized in wound healing remedies for nearly 3000 years. Asiatic acid (AA), a pentacyclic triterpenoid characterized by ursane-type skeleton, serves as principal bioactive constituent of Centella asiatica, exhibits remarkable therapeutic potential across a spectrum of health conditions. Pharmacological investigations have revealed that AA exerts direct regulatory effects on a multitude of enzymes, receptors, inflammatory mediators, and transcription factors. This article systematically examines the therapeutic applications of AA and its derivatives in the management of neurodegenerative diseases, cancer, cardiovascular disorders, and infections. Additionally, recent advancements in the structural modification of AA are summarized, offering new insights for the development of low-toxicity, effective AA-based therapeutics and diagnostic agents. However, several challenges remain, including the paucity of clinical trials, uncertainties in dosage and treatment regimens, limited data on long-term safety and side effects, and poor bioavailability. Addressing these limitations is crucial for advancing AA-based therapies and ensuring their clinical applicability.

Ursonic Acid Ameliorates H2O2-Induced Oxidative Damage in PC12 Cells and Prolonged the Lifespan in C. elegans by Activating MAPKs/Nrf2/HO-1 Signaling Pathway

Growing evidence suggests that plant compounds are emerging as a tremendous source for slowing the onset and progression of Alzheimer's disease (AD). Ursonic acid (UNA) is a naturally occurring pentacyclic triterpenoid with some hypoglycemic, anticancer, and antiinflammatory activities. However, the pharmacological effects of UNA on AD are still unknown. In the present experiments, the effects and mechanisms of UNA on AD were firstly explored by H2O2-induced PC12 cells and Aβ1-42-induced AD model of Caenorhabditis elegans (C. elegans). The results showed that UNA increased the cell viability and the level of mitochondrial membrane potential and reversed apoptosis in H2O2-induced PC12 cells, and Nrf2 and HO-1 were involved in this process. UNA also decreased the phosphorylation of related proteins in the MAPK signaling pathway. Meanwhile, we found that UNA upregulated cellular catalase levels and decreased ROS production. Besides, UNA could activate the Nrf2 /HO-1 signaling pathway and upregulate its protein expression under oxidative stress conditions, whereas Nrf2 and HO-1 inhibitors partially eliminated the protective ability of UNA. The results of in vivo experiments showed that UNA prolonged the lifespan and enhanced the health parameters of AD C. elegans and reduced Aβ1-42-induced neurotoxicity and ROS levels. Moreover, UNA increased GFP-tagged LGG-1 puncta in DA2123 C. elegans. Further mechanistic studies suggested that the protection of UNA on AD C. elegans may be through modulation of the MAPKs/Nrf2/HO-1 pathway. These results highlight the neuroprotective potential of UNA and suggest that UNA may be an effective therapeutic agent for alleviating AD.

Silver Nanoparticles Synthesized From Centella asiatica Extract and Asiatic Acid for Enhanced Biofilm Eradication of Streptococcus Associated With Oral Diseases

The biofilm-forming ability of Streptococcus species, particularly Streptococcus mutans, is a key factor in the pathogenesis of dental caries and periodontitis. Current treatments often exhibit limitations such as incomplete biofilm eradication and cytotoxicity to host tissues, highlighting the need for innovative and biocompatible therapeutic approaches. Therefore, this study aimed to investigate the potential of Centella asiatica ethanolic extract, its bioactive triterpenoids (asiatic acid and madecassic acid), and silver nanoparticles (AgNPs) synthesized from the extract as an alternative strategy for targeting S. mutans biofilms. The antibacterial and antibiofilm activities of the synthesized AgNPs against Streptococcus species were evaluated, alongside cytotoxicity assessments on human gingival fibroblast (HGF-1) cells using the MTT assay. The synthesized AgNPs exhibited superior antimicrobial efficacy compared to the extract, with significantly lower minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values (62.5/125 µg/mL) against S. mutans ATCC 25175 and S. mitis ATCC 49456, highlighting their potent bactericidal activity. Moreover, the AgNPs achieved rapid biofilm disruption, reducing biofilm biomass by 76% within 12 h at 1/2 × MIC, significantly outperforming the extract and triterpenoids. Scanning electron microscopy further revealed substantial extracellular polymeric substance degradation and biofilm structural disruption upon AgNP treatment, confirming their pronounced antibiofilm efficacy. In addition, the synthesized AgNPs demonstrated favorable biocompatibility, maintaining 68% cell viability in dental fibroblast cells, suggesting an optimal balance between antimicrobial potency and cytotoxicity. The synergistic interaction between AgNPs and C. asiatica phytochemicals significantly enhanced biofilm disruption compared to nonfunctionalized AgNPs. These findings underscore the potential of C. asiatica-based AgNPs as a novel, plant-derived nanotechnological approach for managing oral infections caused by biofilm-forming Streptococcus species. This study not only contributes to the development of alternative antibiofilm strategies but also paves the way for future clinical applications in oral healthcare.

Effect of betulinic acid on MepA efflux pump inhibition in Staphylococcus aureus: Antibacterial and molecular study

Infections caused by pathogenic bacteria have been responsible for a significant number of deaths in recent decades. Invasive infections caused by Staphylococcus aureus are highly prevalent and have high morbidity and mortality rates. Faced with the increase in multidrug-resistant bacteria, a promising strategy is the development of adjuvant molecules that enhance the effects of antibiotics, such as efflux pump inhibitors. Betulinic acid (BA) is a pentacyclic triterpene of the lupane type, found in various plant species, which has shown various pharmacological activities, including antibacterial potential. This study investigated the inhibitory action of BA on the MepA efflux pump in strains of Staphylococcus aureus K2068, as well as carrying out fluorescence and membrane permeability tests. The minimum inhibitory concentrations (MIC) were determined using the broth microdilution method. Subsequently, their effects on efflux pump-mediated antibiotic resistance were evaluated by reducing the MIC of the antibiotic and ethidium bromide (EtBr), while fluorimetry and permeability potential tests were carried out using the SYTOX Green fluorescence method. BA did not show intrinsic antibacterial activity, however it showed synergistic effects when associated with the antibiotics ciprofloxacin and ethidium bromide, inducing a reduction in MIC and indicating inhibitory effects on the MepA efflux pump. BA also induced a significant increase in fluorescence and demonstrated the ability to permeabilize the bacterial membrane. The results obtained show that BA has a high potential to act as an efflux pump inhibitor and could help in the treatment of resistant bacterial infections.

Ursolic acid in colorectal cancer: mechanisms, current status, challenges, and future research directions

Colorectal cancer (CRC) ranks as the third most prevalent cancer globally, contributing to approximately 10% of all cancer cases and representing the second leading cause of cancer-related mortality worldwide. Ursolic acid (UA), a widely studied pentacyclic triterpenoid, has attracted substantial attention from researchers and clinicians due to its potential therapeutic effects against malignant tumors. Multiple studies have confirmed that UA inhibits tumor cell proliferation, induces differentiation and apoptosis, suppresses invasion, and impedes tumor angiogenesis via diverse mechanisms. However, research specifically addressing UA's anti-CRC effects remains limited, and systematic reviews of its underlying mechanisms in CRC are scarce. This study seeks to provide a comprehensive review of UA's mechanisms of action against CRC, offering valuable insights and references for researchers and clinicians.

In vitro and in vivo evaluation of novel ursolic acid derivatives as potential antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA)

The misuse and abuse of antibiotics have led to the increase of drug resistance and the emergence of multi-drug resistant bacteria. Therefore, it is an urgent need to develop novel antimicrobial agents to address this problem. Natural products (NPs) could provide an effective strategy for the discovery of drug due to their wide range of source and biological activities. Ursolic acid (UA) is a naturally occurring compound known for its wide range of biological properties. In this study, a series of UA derivatives were rationally designed and synthesized by incorporating antibacterial potential fragments of benzenesulfonamide and indole, with the aim of obtaining novel UA derivatives for the treatment of bacterial infections. Based on the preliminary screening, UA derivatives 27 (yield of 26 %), containing 4-chlorobenzenesulfonamide and 6-carboxyindole pharmacophores, as well as 34 (yield of 42 %), containing 4-carboxybenzenesulfonamide and unsubstituted indole pharmacophores, were identified as promising antibacterial agents against Staphylococcus aureus, especially for methicillin-resistant Staphylococcus aureus (MRSA), possessing MICs of 1 μM. Furthermore, both of them also displayed low hemolytic activity, non-resistance, and low-toxicity to mammalian cells. In addition, further mechanistic studies revealed that 27 and 34 were able to inhibit and eliminate MRSA biofilm formation, affecting the permeability of bacterial cell membrane, leading to increase intracellular reactive oxygen species (ROS) and ultimately inducing bacterial death. Notably, 27 and 34 also showed promising in vivo efficacy against MRSA in a mouse wound model. These results suggested that 27 and 34 should have promising applications against MRSA infection.

Hypolipidemic activity of phytochemical combinations: A mechanistic review of preclinical and clinical studies

Hyperlipidemia, a condition characterized by elevated levels of lipids in the blood, poses a significant risk factor for various health disorders, notably cardiovascular diseases. Phytochemical compounds are promising alternatives to the current lipid-lowering drugs, which cause many undesirable effects. Based on in vivo and clinical studies, combining phytochemicals with other phytochemicals, prebiotics, and probiotics and their encapsulation in nanoparticles is more safe and effective for managing hyperlipidemia than monotherapy. To this end, the results obtained and the mechanisms of action of these combinations were examined in detail in this review.

Potential Activities of Centella asiatica Leaf Extract against Pathogenic Bacteria-Associated Biofilms and Its Anti-Inflammatory Effects

The medicinal value of Centella asiatica leaf extract was evaluated as an alternative treatment. The chemical composition of the leaf extract was analyzed, and the biological activities were determined. High-performance liquid chromatography coupled with a photodiode array detector (HPLC-PDA) was used to identify the asiatic acid, madasiatic acid, and madecassic acid/Brahmic acid isolated from the ethanolic extract. The plant extract at 25 mg/disk was found to inhibit both Gram-positive and Gram-negative pathogenic bacteria by the agar disk diffusion test. The MIC and MBC of the ethanolic extracts were better than those of the aqueous extracts. The ethanolic extracts showed antibacterial activity against Gram-positive bacteria with MICs and MBCs ranging from 1.024 to 2.048 mg/mL and 2.048 to 4.096 mg/mL, respectively. The remarkable antibacterial activities were observed against S. mutans. The ethanolic extract at a concentration of 1/2 × MIC exhibited the inhibition effect on S. mutans biofilm formation like the activity of 0.2% chlorhexidine and significantly modified hydrophobicity of the bacterial cell surface. The effects were confirmed via molecular docking analysis. The binding affinities of asiatic acid, madecassic acid, and madasiatic acid with glucosyltransferase C (GtfC) of S. mutans exhibited superior strength in comparison with alpha-acarbose and chlorhexidine. Moreover, the nitric oxide (NO) secretion of RAW247.6 cells was determined after treating the cells with concentrations of the extract. The C. asiatica ethanolic extract can inhibit the secretion of NO, which can inhibit the inflammatory process. The findings indicate the applications of the C. asiatica ethanolic extract as the alternative anti-S. mutans agent and could be used for further formulation for the treatment and prevention of dental diseases and inflammatory injury in the oral cavity.

Dammarane-Type 3,4-seco-Triterpenoid from Silver Birch (Betula pendula Roth) Buds Induces Melanoma Cell Death by Promotion of Apoptosis and Autophagy

Despite unquestionable advances in therapy, melanoma is still characterized by a high mortality rate. For years, high expectations have been raised by compounds of natural origin as a component of pharmacotherapy, particularly by triterpenes found in the bark of birch trees. In this study, 3,4-seco-dammara-4(29),20(21),24(25)-trien-3-oic acid (SDT) was isolated from buds of silver birch and its mechanisms of cell death induction, including apoptosis and autophagy, were determined. Cytotoxicity of SDT was evaluated by the cell viability test and clonogenic assay, whereas induction of apoptosis and autophagy was determined by annexin V staining and Western blot. The results revealed dose- and time-dependent reductions in viability of melanoma cells. Treatment of cells for 48 h led to an increase in the percentage of annexin V-positive cells, activation of caspase-8, caspase-9, and caspase-3, and cleavage of PARP, confirming apoptosis. Simultaneously, it was found that SDT increased the level of autophagy marker LC3-II and initiator of autophagy beclin-1. Pretreatment of cells with caspase-3 inhibitor or autophagy inhibitor significantly reduced the cytotoxicity of SDT and revealed that both apoptosis and autophagy contribute to a decrease in cell viability. These findings suggest that 3,4-seco-dammaranes may become a promising group of natural compounds for searching for anti-melanoma agents.

Asiatic acid inhibits cervical cancer cell proliferation and migration via PI3K/AKT/mTOR signaling pathway

Cervical cancer (CC) is a malignant tumor of the female reproductive system that typically occurs in cervical cells and has high incidence and mortality rates, strong metastatic ability, and poor prognosis. Asiatic acid (AA) exhibits anti-inflammatory, anti-depressant, and anti-tumor effects. However, the molecular targets and mechanisms underlying AA-mediated inhibition of CC metastasis remain unclear. AA affects the proliferation, metastasis, and epithelial-mesenchymal transition (EMT) process of CC cell lines. MTT experiments verified that AA inhibited the proliferation ability of CC cells, and the effect of AA on the lateral and longitudinal migration ability of CC was evaluated through wound healing and Transwell assays. Western blotting was used to explore whether AA inhibits EMT process in HeLa and C33a cells. Currently, targeting the PI3K/AKT/mTOR pathway as a strategy for cancer treatment remains an evolving field. However, the molecular mechanism by which AA inhibits CC via the PI3K/AKT/mTOR pathway remains unclear and requires further investigation.

Comprehensive in vitro and in vivo evaluation of therapeutic potential of Bacopa-derived asiatic acid against a human oral pathogen Streptococcus mutans

Dental caries is a common human oral disease worldwide, caused by an acid-producing bacteria Streptococcus mutans. The use of synthetic drugs and antibiotics to prevent dental caries has been increasing, but this can lead to severe side effects. To solve this issue, developing and developed countries have resorted to herbal medicines as an alternative to synthetic drugs for the treatment and prevention of dental caries. Therefore, there is an urgent need for plant-derived products to treat such diseases. Bacopa monnieri, a well-documented medicinal plant, contains 52 phytocompounds, including the pentacyclic triterpenoid metabolite known as asiatic acid (ASTA). Hence, this study aimed to demonstrate, for the first time, the antibacterial activity of phytocompound ASTA against S. mutans. The findings revealed that ASTA significantly inhibited the growth of S. mutans and the production of virulence factors such as acidurity, acidogenicity, and eDNA synthesis. Molecular docking analysis evaluated the potential activity of ASTA against S. mutans virulence genes, including VicR and GtfC. Furthermore, toxicity assessment of ASTA in human buccal epithelial cells was performed, and no morphological changes were observed. An in vivo analysis using Danio rerio (zebrafish) confirmed that the ASTA treatment significantly increased the survival rates of infected fish by hindering the intestinal colonization of S. mutans. Furthermore, the disease protection potential of ASTA against the pathognomonic symptom of S. mutans infection was proven by the histopathological examination of the gills, gut, and kidney. Overall, these findings suggest that ASTA may be a promising therapeutic and alternative drug for the treatment and prevention of oral infection imposed by S. mutans.

Identification of TonB-dependent siderophore receptor inhibitors against Flavobacterium columnare using a structure-based high-throughput virtual screening method

TonB-dependent siderophore receptors play a critical transport role for Flavobacterium columnare virulence formation and growth, and have become valuable targets for the development of novel antimicrobial agents. Traditional Chinese medicine has demonstrated notable efficacy in the treatment of fish diseases and includes potential antibacterial agents. Herein, we performed molecular docking-based virtual screening to discover novel TonB-dependent siderophore receptor inhibitors from traditional Chinese medicine and provide information for developing novel antibacterial agents. Firstly, we efficiently obtained 11 potential inhibitors with desirable drug-like characteristics from thousands of compounds in the TCM library based on virtual screening and property prediction. The antibacterial activity of Enoxolone, along with its interaction characteristics, were determined via an MIC assay and molecular dynamic simulation. Transcriptional profiling, along with validation experiments, subsequently revealed that an insufficient uptake of iron ions by bacteria upon binding to the TonB-dependent siderophore receptors is the antibacterial mechanism of Enoxolone. Finally, Enoxolone's acceptable toxicity was illustrated through immersion experiments. In summary, we have used virtual screening techniques for the first time in the development of antimicrobial agents in aquaculture. Through this process, we have identified Enoxolone as a promising compound targeting the TonB-dependent siderophore receptor of F. columnare. In addition, our findings will provide new ideas for the advancement of innovative antimicrobial medications in aquaculture.

Evaluation of the mechanistic basis for the antibacterial activity of ursolic acid against Staphylococcus aureus

The antibiotics are generally regarded as the first choice approach to treat dairy mastitis, targeting the public health problems associated with the food safety and the emergence of antibioticresistant bacteria. The objective of the study was to evaluate the antibacterial efficacy of ursolic acid (UA) when used to treat Staphylococcus aureus and other isolates associated with bovine mastitis and to clarify the mechanistic basis for these effects. The bacteriostatic properties of UA extracted from Rosmarinus officinalis L. at four different purity levels were assessed by calculating minimum inhibitory concentration (MIC) values, while the synergistic effects of combining 98% UA with antibiotics were evaluated by measuring the fractional inhibitory concentration index (FICI). Changes in biofilm formation and the growth curves of the clinical isolates were assessed to clarify the bacteriostatic effect of UA. Furthermore, the cell wall integrity, protein synthesis, and reactive oxygen species (ROS) production were assessed to determine the antibacterial mechanism of UA treatment. Ultimately, UA was revealed to exhibit robust activity against Gram-positive bacteria including S. aureus (ATCC 25923), Streptococcus dysgalactiae (ATCC27957), Streptococcus agalactiae (ATCC13813), Enterococcus faecalis (ATCC29212), and Streptococcus mutans (ATCC25175). However, it did not affect Escherichia coli (ATCC 25922). The MIC values of UA preparations that were 98, 50, 30, and 10% pure against S. aureus were 39, 312, 625, and 625 μg/mL, respectively, whereas the corresponding MIC for E. coli was >5,000 μg/mL. The minimum bactericidal concentrations of 98% UA when used to treat three clinical S. aureus isolates (S4, S5, and S6) were 78, 78, and 156 μg/mL, respectively. Levels of biofilm formation for clinical S. aureus isolates decreased with increasing 98% UA concentrations. Above the MIC dose, UA treatment resulted in the dissolution of bacterial cell walls and membranes, with cells becoming irregularly shaped and exhibiting markedly impaired intracellular protein synthesis. S. aureus treated with 98% UA was able to rapidly promote intracellular ROS biogenesis. Together, these data highlight the promising utility of UA as a compound that can be used together with other antibiotics for the treatment of infections caused by S. aureus.

Ursolic acid alleviates meiotic abnormalities induced by 3-nitropropionic acid in mouse oocytes

3-nitropropionic acid (3-NPA), a toxic metabolite produced by mold, is mainly found in moldy sugarcane. 3-NPA inhibits the activity of succinate dehydrogenase that can induce oxidative stress injury in cells, reduce ATP production and induce oxidative stress in mouse ovaries to cause reproductive disorders. Ursolic acid (UA) has a variety of biological activities and is a pentacyclic triterpene compound found in many plants. This experiment aimed to investigate the cytotoxicity of 3-NPA during mouse oocyte in vitro maturation and the protective effects of UA on oocytes challenged with 3-NPA. The results showed that UA could alleviate 3-NPA-induced oocyte meiotic maturation failure. Specifically, 3-NPA induced a decrease in the first polar body extrusion rate of oocytes, abnormal distribution of cortical granules, and an increase in the proportion of spindle abnormalities. In addition, 3-NPA caused mitochondrial dysfunction and induced oxidative stress, including decreases in the GSH, mitochondrial membrane potential and ATP levels, and increases in the ROS levels, and these effects led to apoptosis and autophagy. The addition of UA could significantly improve the adverse effects caused by 3-NPA. In general, our data show that 3-NPA affects the normal development of oocytes during the in vitro culture, and the addition of UA can effectively repair the damage caused by 3-NPA to oocytes.

Investigating the Neuroprotective and Cognitive-Enhancing Effects of Bacopa monnieri: A Systematic Review Focused on Inflammation, Oxidative Stress, Mitochondrial Dysfunction, and Apoptosis

The aging of the global population has increased the prevalence of neurodegenerative conditions. Bacopa monnieri (BM), an herb with active compounds, such as bacosides A and B, betulinic acid, loliolide, asiatic acid, and quercetin, demonstrates the potential for brain health. Limited research has been conducted on the therapeutic applications of BM in neurodegenerative conditions. This systematic review aims to project BM's beneficial role in brain disorders. BM has anti-apoptotic and antioxidant actions and can repair damaged neurons, stimulate kinase activity, restore synaptic function, improve nerve transmission, and increase neuroprotection. The included twenty-two clinical trials demonstrated that BM can reduce Nuclear Factor-κB phosphorylation, improve emotional function, cognitive functions, anhedonia, hyperactivity, sleep routine, depression, attention deficit, learning problems, memory retention, impulsivity, and psychiatric problems. Moreover, BM can reduce the levels of pro-inflammatory biomarkers and oxidative stress. Here, we highlight that BM provides notable therapeutic benefits and can serve as a complementary approach for the care of patients with neurodegenerative conditions associated with brain disorders. This review adds to the growing interest in natural products and their potential therapeutic applications by improving our understanding of the mechanisms underlying cognitive function and neurodegeneration and informing the development of new therapeutic strategies for neurodegenerative diseases.

Exploring the Bioactive Potential of Pisolithus (Basidiomycota): Comprehensive Insights into Antimicrobial, Anticancer, and Antioxidant Properties for Innovative Applications

Addressing pressing health concerns, modern medical research seeks to identify new antimicrobials to combat drug resistance, novel molecules for cancer treatment, and antioxidants for inflammation-related diseases. Pisolithus (Basidiomycota) is a ubiquitous and widely distributed fungal genus in forest ecosystems, known for establishing ectomycorrhizal associations with a range of host plants, enhancing their growth, and conferring protection against biotic and abiotic stresses. Beyond ecological applications, Pisolithus yields bioactive compounds with medicinal potential. This comprehensive review explores the transversal biological activity of Pisolithus fungi, aiming to provide a thorough overview of their antimicrobial, anticancer, and antioxidant potential. The focus is on elucidating bioactive compounds within Pisolithus to trigger further research for innovative applications. Compounds from Pisolithus displayed antimicrobial activity against a broad spectrum of microorganisms, including antibiotic-resistant bacteria. The efficacy of Pisolithus-derived compounds matched established medications, emphasizing their therapeutic potential. In anticancer research, the triterpene pisosterol stood out with documented cytotoxicity against various cancer cell lines, showcasing promise for novel anticancer therapies. Pisolithus was also recognized as a potential source of antioxidants, with basidiocarps exhibiting high antioxidant activity. In vivo validation and comprehensive studies on a broader range of compounds, together with mechanistic insights into the mode of action of Pisolithus-derived compounds, are compelling areas for future research.

Exploration of anti‑osteosarcoma activity of asiatic acid based on network pharmacology and in vitro experiments

Osteosarcomas are malignant bone tumors that typically originate in the epiphyses of the long bones of the extremities in adolescents. Asiatic acid has been reported to possess anti‑inflammatory, neuroprotective, antidiabetic, antitumor and antimicrobial activities. The present study used a combination of network pharmacological prediction and in vitro experimental validation to explore the potential pharmacological mechanism of asiatic acid against osteosarcoma. A total of 78 potential asiatic acid targets in osteosarcoma were identified using databases. Kyoto Encyclopedia of Genes and Genomes analysis indicated that the PI3K/AKT and MAPK signaling pathways are essential in the treatment of osteosarcoma with asiatic acid. Molecular docking revealed binding of asiatic acid to EGFR, Caspase‑3, ESR1, HSP90AA1, IL‑6 and SRC proteins. asiatic acid inhibited proliferation through G2/M cell cycle arrest in osteosarcoma cells. In addition, asiatic acid induced mitochondria‑dependent apoptosis as demonstrated by increases in Bax and VDAC1 expression, and a decrease in Bcl‑2 protein expression. The increased autophagosomes, increased LC3‑II/I ratios and decreased p62 expression in the treatment group indicated that asiatic acid triggered autophagy. In addition, asiatic acid decreased the levels of phosphorylated (p‑)PI3K/PI3K and p‑AKT/AKT, increased reactive oxygen species (ROS) and upregulated the levels of p‑ERK1/2/ERK1/2, p‑p38/p38 and p‑JNK/JNK in osteosarcoma cells. These results demonstrated that asiatic acid inhibited osteosarcoma cells proliferation by inhibiting PI3K/AKT and activating ROS/MAPK signaling pathways, suggesting asiatic acid is a potential agent against osteosarcoma.

Examining the Effects of Asiaticoside on Dental Pulp Stem Cell Viability and Proliferation: A Promising Approach to Root Canal Treatment

AIM

This study aims to evaluate the impact of asiaticoside (AC) on the viability and proliferation of dental pulp stem cells (DPSCs), considering the known negative effects of routinely used intracanal medicaments. This evaluation will be compared with the outcomes from using traditional intracanal medicaments, specifically triple antibiotic paste (TAP) and calcium hydroxide [Ca(OH)2].

MATERIALS AND METHODS

The DPSCs were obtained from the third molars of an adult donor. The application of flow cytometry was employed to do a phenotypic analysis on DPSCs using CD90, CD73, CD105, CD34, CD14, and CD45 antibodies. The methylthiazol tetrazolium (MTT) assay was employed to assess cellular viability. The cells were treated with different concentrations of TAP and Ca(OH)2 (5, 2.5, 1, 0.5, and 0.25 mg/mL), along with AC (100, 50, 25, 12.5, and 6.25 µM). A cell proliferation rate was performed at 3, 5, and 7 days.

RESULTS

The characterization of DPSCs was conducted by flow cytometry analysis, which verified the presence of mesenchymal cell surface antigen molecules (CD105, CD73, and CD90) and demonstrated the absence of hematopoietic markers (CD34, CD45, and CD14). Cells treated with concentrations over 0.5 mg/mL of TAP and Ca(OH)2 showed a notable reduction in cell viability in comparison to the untreated cells (p < 0.05). Additionally, the cells treated with different concentrations of AC 12.5, 6.25, 25, and 50 µM did not differ significantly from the untreated cells (p > 0.05). Nevertheless, cells treated with concentrations of 100 µM showed a significant reduction in viability compared to the untreated cells (p < 0.05). After a period of 7 days, it was noted that cells exposed to three different concentrations of AC (50, 25, and 12.5 µM) had a notable rise in cell density in comparison to TAP and Ca(OH)2 (p < 0.05). Furthermore, cells that were exposed to a concentration of 12.5 µM exhibited the highest cell density.

CONCLUSION

The cellular viability of the AC-treated cells was superior to that of the TAP and Ca(OH)2-treated cells. Moreover, the AC with a concentration of 12.5 µM had the highest degree of proliferation.

CLINICAL SIGNIFICANCE

This study underscores the importance of evaluating alternative root canal medicaments and their effects on DPSCs' growth and vitality. The findings on AC, particularly its influence on the survival and proliferation of DPSCs, offer valuable insights for its probable use as an intracanal medication. This research contributes to the ongoing efforts to identify safer and more effective intracanal treatments, which are crucial for enhancing patient outcomes in endodontic procedures. How to cite this article: Alazemi MJ, Badawi MF, Elbeltagy MG, et al. Examining the Effects of Asiaticoside on Dental Pulp Stem Cell Viability and Proliferation: A Promising Approach to Root Canal Treatment. J Contemp Dent Pract 2024;25(2):118-127.

The effect of κ-carrageenan and ursolic acid on the physicochemical properties of the electrospun nanofibrous mat for biomedical application

Wound dressing materials such as nanofiber (NF) mats have gained a lot of attention in recent years owing to their wonderful effect on accelerating the healing process and protection of wounds. In this regard, three different types of NF mats were fabricated using pure polyvinylpyrrolidone (PVP), PVP/κ-carrageenan (KG), and ursolic acid (UA) in the optimal PVP/KG ratio by electrospinning method to apply them as wound dressings. The morphology, chemical structure, degradation, porosity, mechanical properties and antioxidant activity of the produced NFs were investigated. Moreover, cell studies (e.g., cell proliferation, adhesion, and migration) and their antibacterial properties were evaluated. Adding KG and UA reduced the mean diameter size of the PVP-based NFs to ∼98 nm in the optimal sample, with defect-free morphology. The PVP/KG/UA 0.25 % exhibited the highest porosity, hydrophilicity, and degradation rate and a wound closure rate of 60 %, 2.5 times higher than that of the control group. Furthermore, this sample's proliferation and antibacterial ability were significantly higher than the other groups. These findings confirmed that the produced UA-loaded NFs have excellent properties as wound dressing.

Antibacterial and antibiofilm effects of green synthesized selenium nanoparticles on clinical Klebsiella pneumoniae isolates

Nanotechnology covers many disciplines, including the biological sciences. In this study, selenium nanoparticles (Se-NPs) were synthesized using Artemisia annua extract and investigated against clinical strains of klebsiella pneumoniae (K. pneumoniae) for their anti-biofilm effects. In this experimental study, from May 1998 to September 1998, 50 clinical samples of blood, urine, and sputum were collected, and K. pneumoniae strains were isolated using microbiological methods. Subsequently, the antibacterial effects of Se-NPs at concentrations of 12-25-50-100/5-6/3-25/125 μg/mL were studied. Finally, biofilm-producing strains were isolated, and the expression of mrkA biofilm gene was studied in real-time strains treated with Se-NPs using real-time polymerase chain reaction (PCR). Out of 50 clinical samples, 20 strains of K. pneumoniae were isolated. Minimum inhibitory concentration (MIC) results of Se-NPs showed that Se-NPs were capable of significant cell killing. Real-time PCR results also showed that mrkA gene expression was significantly reduced in strains treated with Se-NPs. According to this study, Se-NPs could reduce bacterial growth and biofilm formation, therefore, could be considered a candidate drug in the medical application for infections caused by K. pneumoniae.

Ursolic acid-loaded chitosan nanoparticles suppress 7,12-dimethylbenz(a)anthracene-induced oral tumor formation through their antilipid peroxidative potential in golden Syrian hamsters

Oral cancer, a disfiguring and life threatening cancer, significantly affects the day-to-day life of not only the patients but also their family members in terms of life quality and financial burden. India records higher incidence of oral cancer every year and is mainly due to the habituation of tobacco products and alcohol abuse. Delay in diagnosis and treatment influences India's higher incidence of oral cancer, where annually 50,000-60,000 oral carcinoma cases are reported. 7,12-dimethylbenz(a)anthracene (DMBA)-induced cancer in the oral cavity mimics human oral cancer in histopathological, molecular, and morphological aspects, and thus, by using this paradigm, the tumor inhibiting efficacy of medicinal plants or herbs and their components is scientifically validated. Ursolic acid, due to its multiple pharmacological effects, has been attracted, in recent years, for chemoprevention research program. Though, ursolic acid has been shown to have beneficial effects, its poor water solubility and bioavailability hinder to exert its 100% efficacy. Therefore, ursolic acid is encapsulated in either natural or synthetic polymers to enhance its therapeutic efficacy. Chitosan is one of the natural polymers that have been employed in the synthesis of nanoparticles to improve the drug efficacy. The present study has thus chosen ursolic acid-loaded chitosan nanoparticles (UACNP) to assess its anticancer efficacy in the DMBA-induced oral carcinoma. The anticancer efficacy of UACNP in experimental oral carcinogenesis was assessed by employing the status of oxidative markers and detoxification cascade as an end point. DMBA-induced abnormalities in the status of oxidative markers and detoxification cascade were reversed by ursolic acid-loaded chitosan nanoparticles. The tumor inhibiting or suppressing effect of UACNP is thus explored in experimental oral carcinogenesis.

Ursolic acid: biological functions and application in animal husbandry

Ursolic acid (UA) is a plant-derived pentacyclic triterpenoid with 30 carbon atoms. UA has anti-inflammatory, antioxidative, antimicrobial, hepato-protective, anticancer, and other biological activities. Most studies on the biological functions of UA have been performed in mammalian cell (in vitro) and rodent (in vivo) models. UA is used in animal husbandry as an anti-inflammatory and antiviral agent, as well as for enhancing the integrity of the intestinal barrier. Although UA has been shown to have significant in vitro bacteriostatic effects, it is rarely used in animal nutrition. The use of UA as a substitute for oral antibiotics or as a novel feed additive in animal husbandry should be considered. This review summarizes the available data on the biological functions of UA and its applications in animal husbandry.

Anti-Biofilm Activity of Chlorogenic Acid against Pseudomonas Using Quorum Sensing System

Chlorogenic acid is a secondary metabolite produced by many traditional Chinese medicines. Its physiological activities (antibacterial, anti-inflammatory, antioxidant activities, etc.) have been well described. This study aimed to investigate the effects of chlorogenic acid on the biofilm of drinking water bacteria. The effects of chlorogenic acid on the metabolites of the biofilms were also evaluated. Chlorogenic acid was found to have an anti-biofilm effect against Pseudomonas, resulting in biofilm formation in a dose-dependent manner (0.53-25.4 mM CGA). Moreover, the biofilm structure was visibly attenuated. Furthermore, we identified and characterized 23 differential metabolites and associated two metabolic pathways involving beta-alanine metabolism and pyrimidine metabolism that were altered mostly during biofilm formation. A quantitative real-time PCR assay revealed that chlorogenic acid interfered with the signaling molecule synthesis and transcription regulators using the Las, Pqs and Rhl systems. These findings suggest that chlorogenic acid can be a quorum sensing (QS) inhibitor and inhibit biofilm formation. It may be a promising natural product for the prevention of contaminated drinking water.

Triterpenes as Potential Drug Candidates for Rheumatoid Arthritis Treatment

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease characterized by joint inflammation, swelling and pain. Although RA mainly affects the joints, the disease can also have systemic implications. The presence of autoantibodies, such as anti-cyclic citrullinated peptide antibodies and rheumatoid factors, is a hallmark of the disease. RA is a significant cause of disability worldwide associated with advancing age, genetic predisposition, infectious agents, obesity and smoking, among other risk factors. Currently, RA treatment depends on anti-inflammatory and disease-modifying anti-rheumatic drugs intended to reduce joint inflammation and chronic pain, preventing or slowing down joint damage and disease progression. However, these drugs are associated with severe side effects upon long-term use, including immunosuppression and development of opportunistic infections. Natural products, namely triterpenes with anti-inflammatory properties, have shown relevant anti-arthritic activity in several animal models of RA without undesirable side effects. Therefore, this review covers the recent studies (2017-2022) on triterpenes as safe and promising drug candidates for the treatment of RA. These bioactive compounds were able to produce a reduction in several RA activity indices and immunological markers. Celastrol, betulinic acid, nimbolide and some ginsenosides stand out as the most relevant drug candidates for RA treatment.

Delving into the Mechanisms of Sponge-Associated Enterobacter against Staphylococcal Biofilms

Staphylococci are one of the most common causes of biofilm-related infections. Such infections are hard to treat with conventional antimicrobials, which often lead to bacterial resistance, thus being associated with higher mortality rates while imposing a heavy economic burden on the healthcare system. Investigating antibiofilm strategies is an area of interest in the fight against biofilm-associated infections. Previously, a cell-free supernatant from marine-sponge-associated Enterobacter sp. inhibited staphylococcal biofilm formation and dissociated the mature biofilm. This study aimed to identify the chemical components responsible for the antibiofilm activity of Enterobacter sp. Scanning electron microscopy confirmed that the aqueous extract at the concentration of 32 μg/mL could dissociate the mature biofilm. Liquid chromatography coupled with high-resolution mass spectrometry revealed seven potential compounds in the aqueous extract, including alkaloids, macrolides, steroids, and triterpenes. This study also suggests a possible mode of action on staphylococcal biofilms and supports the potential of sponge-derived Enterobacter as a source of antibiofilm compounds.

Determination of Pentacyclic Triterpenoids in Plant Biomass by Porous Graphitic Carbon Liquid Chromatography-Tandem Mass Spectrometry

Pentacyclic triterpenoids (PCTs), which possess a number of bioactive properties, are considered one of the most important classes of secondary plant metabolites. Their chromatographic determination in plant biomass is complicated by the need to separate a large number of structurally similar compounds belonging to several classes that differ greatly in polarity (monools, diols, and triterpenic acids). This study proposes a rapid, sensitive, and low-cost method for the simultaneous quantification of ten PCTs (3β-taraxerol, lupeol, β-amyrin, α-amyrin, betulin, erythrodiol, uvaol, betulinic, oleanolic, and ursolic acids) by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) using porous graphitic carbon (Hypercarb) as a stationary phase capable of hydrophobic retention and specific interactions with analytes. Revealing the effects of the mobile phase composition, pH, ionic strength, and column temperature on retention and selection of chromatographic conditions on this basis allowed for the effective separation of all target analytes within 8 min in gradient elution mode and attaining limits of detection in the range of 4-10⁴ µg L^-1. The developed method was fully validated and successfully tested in the determination of PCTs in common haircap (Polytrichum commune) and prairie sphagnum (Sphagnum palustre) mosses, and fireweed (Chamaenerion angustifolium) stems and leaves.

Neuroprotective mechanisms of Asiatic acid

Asiatic acid (AA) is the most crucial component of Asiaticoside in many edible and medicinal plants. It has diverse biological activities such as anti-inflammatory, antioxidant, anti-infective, and anti-tumor. Additionally, AA has been intensively studied in the last decades. It has shown great potential in the treatment of various neurological diseases such as spinal cord injury (SCI), cerebral ischemia, epilepsy, traumatic brain injury (TBI), neural tumors, Alzheimer's disease (AD), and Parkinson's disease (PD). Moreover, AA provides pertinent data for neuroprotective signaling pathways, and its substantial neuroprotective ability makes it a novel candidate for developing drugs that target the central nervous system.

Phytochemical Screening, Antibacterial, Antifungal, Anti-Biofilm and Antioxidant Activity of Azadiracta Indica A. Juss. Flowers

The present study involves investigation of Azadiracta Indica flowers with respect to its pharmacognostic properties, phytochemical screening, and its application as anti-oxidant, anti-biofilm, and anti-microbial agent. The Pharmacognostic characteristics were evaluated with respect to moisture content, total ash content, acid, and water-soluble ash content, swelling index, foaming index, and metal content. The macro and micronutrient content of the crude drug was estimated by AAS and Flame photometric methods and it gives the quantitative estimation of minerals, where calcium is present in abundance (88.64 mg/L). Soxhlet extraction was carried out in the increasing order of polarity of the solvent viz Petroleum Ether (PE), Acetone (AC), and Hydroalcohol (20 %) (HA) to extract the bioactive compounds. The characterization of the bioactive compounds of all the three extract have been carried out using gcms and lcms. The presence of 13 major compounds have been identified in PE extract and 8 compounds in AC extract using gcms studies. The HA extract is found to contain polyphenols, flavanoids, and glycosides. The antioxidant activity of the extracts was evaluated by DPPH, FRAP, and Phosphomolybdenum assay. This reveals that HA extract shows good scavenging activity than PE and AC extracts which is well correlated with the bioactive compounds, especially phenols which are present as a major component in the extract. The anti-microbial activity was investigated via Agar well diffusion method for all the extracts. Among all the extracts HA extract shows good antibacterial activity with MIC of 25 μg/mL and AC extract shows good anti-fungal activity with MIC of 25 μg/mL. The antibiofilm assay confirms that the HA extract shows good biofilm inhibition about 94 % among other extracts when tested on human pathogens. The results confirm that the HA extract of A. Indica flowers will be an excellent source of natural anti-oxidant and also antimicrobial agents. This paves the way for its potential uses in herbal product formulation.

Ursolic Acid Analogs as Potential Therapeutics for Cancer

Ursolic acid (UA) is a pentacyclic triterpene isolated from a large variety of vegetables, fruits and many traditional medicinal plants. It is a structural isomer of Oleanolic Acid. The medicinal application of UA has been explored extensively over the last two decades. The diverse pharmacological properties of UA include anti-inflammatory, antimicrobial, antiviral, antioxidant, anti-proliferative, etc. Especially, UA holds a promising position, potentially, as a cancer preventive and therapeutic agent due to its relatively non-toxic properties against normal cells but its antioxidant and antiproliferative activities against cancer cells. Cell culture studies have shown interference of UA with multiple pharmacological and molecular targets that play a critical role in many cells signaling pathways. Although UA is considered a privileged natural product, its clinical applications are limited due to its low absorption through the gastro-intestinal track and rapid elimination. The low bioavailability of UA limits its use as a therapeutic drug. To overcome these drawbacks and utilize the importance of the scaffold, many researchers have been engaged in designing and developing synthetic analogs of UA via structural modifications. This present review summarizes the synthetic UA analogs and their cytotoxic antiproliferative properties reported in the last two decades.

Ursolic acid: a natural modulator of signaling networks in different cancers

Incidence rate of cancer is estimated to increase by 40% in 2030. Furthermore, the development of resistance against currently available treatment strategies has contributed to the cancer-associated mortality. Scientists are now looking for the solutions that could help prevent the disease occurrence and could provide a pain-free treatment alternative for cancers. Therefore, efforts are now put to find a potent natural compound that could sever this purpose. Ursolic acid (UA), a triterpene acid, has potential to inhibit the tumor progression and induce sensitization to conventional treatment drugs has been documented. Though, UA is a hydrophobic compound therefore it is usually chemically modified to increase its bioavailability prior to administration. However, a thorough literature indicating its mechanism of action and limitations for its use at clinical level was not reviewed. Therefore, the current study was designed to highlight the potential mechanism of UA, its anti-cancer properties, and potential applications as therapeutic compound. This endeavour is a valuable contribution in understanding the hurdles preventing the translation of its potential at clinical level and provides foundations to design new studies that could help enhance its bioavailability and anti-cancer potential for various cancers.

Daniellia oliveri (Rolfe) Hutch and Dalziel: Antimicrobial Activities, Cytotoxicity Evaluation, and Phytochemical Identification by GC-MS

During a previous study that identified plants used in traditional medicine in Togo to treat infectious diseases, Daniellia oliveri was specifically reported to treat intertrigo and candidiasis. Consequently, to explore the anti-infective potential of this plant, we investigated the antibacterial and the antifungal activity of the plant's parts, as well as the cytotoxic activities of raw extracts and subsequent fractions, and the chemical composition of the most active fractions. In order to evaluate the antimicrobial activity, MICs were determined using the broth dilution method. Then, the most active fractions were evaluated for cytotoxicity by using normal human cells (MRC-5 cells) via the MTT assay. Finally, the most active and not toxic fractions were phytochemically investigated by GC-MS. Interestingly, all the raw extracts and fractions were active against the bacteria tested, with MICs ranging from 16 µg/mL to 256 µg/mL, while no antifungal activity was observed at 256 µg/mL, the highest tested concentration. Moreover, no toxicity was observed with most of the active fractions. The subsequent chemical investigation of the most interesting fractions led to identifying terpenes, phytosterols, phenolic compounds, and fatty acids as the main compounds. In conclusion, this study demonstrated that D. oliveri possesses valuable antibacterial activities in accordance with traditional use.

Potential Benefits of Black Chokeberry (Aronia melanocarpa) Fruits and Their Constituents in Improving Human Health

Aronia berry (black chokeberry) is a shrub native to North America, of which the fresh fruits are used in the food industry to produce different types of dietary products. The fruits of Aronia melanocarpa (Aronia berries) have been found to show multiple bioactivities potentially beneficial to human health, including antidiabetic, anti-infective, antineoplastic, antiobesity, and antioxidant activities, as well as heart-, liver-, and neuroprotective effects. Thus far, phenolic compounds, such as anthocyanins, cyanidins, phenolic acids, proanthocyanidins, triterpenoids, and their analogues have been identified as the major active components of Aronia berries. These natural products possess potent antioxidant activity, which contributes to the majority of the other bioactivities observed for Aronia berries. The chemical components and the potential pharmaceutical or health-promoting effects of Aronia berries have been summarized previously. The present review article focuses on the molecular targets of extracts of Aronia berries and the examples of promising lead compounds isolated from these berries, including cyanidin-3-O-galactoside, chlorogenic acid, quercetin, and ursolic acid. In addition, presented herein are clinical trial investigations for Aronia berries and their major components, including cancer clinical trials for chlorogenic acid and COVID-19 trial studies for quercetin. Additionally, the possible development of Aronia berries and their secondary metabolites as potential therapeutic agents is discussed. It is hoped that this contribution will help stimulate future investigations on Aronia berries for the continual improvement of human health.

Antibiofilm and Anti-Quorum Sensing Potential of Cycloartane-Type Triterpene Acids from Cameroonian Grassland Propolis: Phenolic Profile and Antioxidant Activity of Crude Extract

Propolis is very popular for its beneficial health properties, such as antimicrobial activity and antioxidant effects. It is one of the most long-serving traditional medicines to mankind due to its interesting chemical diversity and therapeutic properties. The detailed chemical information of propolis samples is very necessary to guarantee its safety and for it to be accepted into health care systems. The phenolic profile of the hydroethanolic extract was determined using HPLC-DAD, and the antioxidant was evaluated using five complementary methods. Triterpenoids were isolated using column chromatography and characterized using 1H NMR and 13C NMR. The effects of the extract and the isolated compounds on quorum sensing mediated processes and biofilm formation in bacteria were evaluated. Protocatechic acid (40.76 ± 0.82 µg/g), 4-hydroxybenzoic acid (24.04 ± 0.21 µg/g), vanillic acid (29.90 ± 1.05 µg/g), quercetin (43.53 ± 1.10 µg/g), and luteolin (4.44 ± 0.48 µg/g) were identified and quantified. The extract showed good antioxidant activity in the DPPH•, ABTS•+, CUPRAC, and metal chelating assays, and this antioxidant effect was confirmed by cyclic voltammetry. 27-Hydroxymangiferonic acid (1), Ambolic acid (2), and Mangiferonic acid (3) were isolated from anti-quorum sensing activity at MIC, and it was indicated that the most active sample was the extract with inhibition diameter zone of 18.0 ± 1.0 mm, while compounds 1, 2, and 3 had inhibition zones of 12.0 ± 0.5 mm, 9.0 ± 1.0 mm, and 12.3 ± 1.0 mm, respectively. The samples inhibited the P. aeruginosa PA01 swarming motility at the three tested concentrations (50, 75, and 100 μg/mL) in a dose-dependent manner. The propolis extract was able to inhibit biofilm formation by S. aureus, E. coli, P. aeruginosa, C. albicans, and C. tropicalis at MIC concentration. Compound 1 proved biofilm inhibition on S. aureus, L. monocytogenes, E. faecalis, E. coli, and C. tropicalis at MIC and MIC/2; compound 2 inhibited the formation of biofilm at MIC on S. aureus, E. faecalis, E. coli, S. typhi, C. albicans, and C. tropicalis; and compound 3 inhibited biofilm formation on E. faecalis, E. coli, C. albicans, and C. tropicalis and further biofilm inhibition on E. coli at MIC/4 and MIC/8. The studied propolis sample showed important amounts of cycloartane-type triterpene acids, and this indicates that there can be significant intra-regional variation probably due to specific flora within the vicinity. The results indicate that propolis and its compounds can reduce virulence factors of pathogenic bacteria.

Synthesis and Biological Evaluation of Novel Allobetulon/Allobetulin-Nucleoside Conjugates as AntitumorAgents

Allobetulin is structurally similar tobetulinic acid, inducing the apoptosis of cancer cells with low toxicity. However, both of them exhibited weak antiproliferation against several tumor cell lines. Therefore, the new series of allobetulon/allobetulin–nucleoside conjugates 9a–10i were designed and synthesized for potency improvement. Compounds 9b, 9e, 10a, and 10d showed promising antiproliferative activity toward six tested cell lines, compared to zidovudine, cisplatin, and oxaliplatin based on their antitumor activity results. Among them, compound 10d exhibited much more potent antiproliferative activity against SMMC-7721, HepG2, MNK-45, SW620, and A549 human cancer cell lines than cisplatin and oxaliplatin. In the preliminary study for the mechanism of action, compound 10d induced cell apoptosis and autophagy in SMMC cells, resulting in antiproliferation and G0/G1 cell cycle arrest by regulating protein expression levels of Bax, Bcl-2, and LC3. Consequently, the nucleoside-conjugated allobetulin (10d) evidenced that nucleoside substitution was a viable strategy to improve allobetulin/allobetulon’s antitumor activity based on our present study.

Targeting the Holy Triangle of Quorum Sensing, Biofilm Formation, and Antibiotic Resistance in Pathogenic Bacteria

Chronic and recurrent bacterial infections are frequently associated with the formation of biofilms on biotic or abiotic materials that are composed of mono- or multi-species cultures of bacteria/fungi embedded in an extracellular matrix produced by the microorganisms. Biofilm formation is, among others, regulated by quorum sensing (QS) which is an interbacterial communication system usually composed of two-component systems (TCSs) of secreted autoinducer compounds that activate signal transduction pathways through interaction with their respective receptors. Embedded in the biofilms, the bacteria are protected from environmental stress stimuli, and they often show reduced responses to antibiotics, making it difficult to eradicate the bacterial infection. Besides reduced penetration of antibiotics through the intricate structure of the biofilms, the sessile biofilm-embedded bacteria show reduced metabolic activity making them intrinsically less sensitive to antibiotics. Moreover, they frequently express elevated levels of efflux pumps that extrude antibiotics, thereby reducing their intracellular levels. Some efflux pumps are involved in the secretion of QS compounds and biofilm-related materials, besides being important for removing toxic substances from the bacteria. Some efflux pump inhibitors (EPIs) have been shown to both prevent biofilm formation and sensitize the bacteria to antibiotics, suggesting a relationship between these processes. Additionally, QS inhibitors or quenchers may affect antibiotic susceptibility. Thus, targeting elements that regulate QS and biofilm formation might be a promising approach to combat antibiotic-resistant biofilm-related bacterial infections.

In vitro growth inhibitory effect of selected 18β-glycyrrhetinic acid esters on Theileriaannulata

Glycyrrhetinic acid (GA) is one of the important Pentacyclic Triterpenoids (PT) found in the roots of licorice. This study aimed to evaluate the in vitro growth inhibitory effect of 18β-GA (18β-Glycyrrhetinic acid) and C-30 esters against Theileria annulata, the causative agent of Tropical Bovine Theileriosis. C-30 esters of 18β-GA were synthesized and their structures were elucidated using spectroscopy. The pharmacodynamic properties of 18β-GA and its C-30 esters were predicted using DataWarrior and Swiss ADME tools. Cattle isolates of T. annulata schizont-infected bovine lymphoblastoid cells were cultured using standard conditions and the growth inhibitory effect of GA and its esters were evaluated using MTT assay. The isopropyl ester of 18β-GA (GI₅₀- 1.638 μM; R²- 0.818) showed improved anti-theileriosis efficacy than other 18β-GA derivatives. The propyl (GI₅₀ - 5.549 μM), ethyl (GI₅₀ - 5.638 μM), and benzyl (GI₅₀ - 7.431 μM) esters also showed considerable inhibitory effect. The GI₅₀ value for 18β-GA was recorded as 6.829 μM. This study throws light on the usefulness of 18β-GA and its esters for the treatment of Tropical Bovine Theileriosis.