Ursolic and oleanolic acids as antimicrobial and immunomodulatory compounds for tuberculosis treatment

Promising Ursolic Acid as a Novel Antituberculosis Agent: Current Progress and Challenges

Tuberculosis (TB) stands as the second most prevalent cause of global human mortality from infectious diseases. In 2022, the World Health Organization documented an estimated number of global TB cases reaching 7.5 million, which causes death for 1.13 million patients. The continuous growth of drug-resistant TB cases due to various mutations in the Mycobacterium tuberculosis (MTB) strain, raises the urgency of the exploration of novel anti-TB treatments. Ursolic acid (UA) is a natural pentacyclic triterpene found in various plants that has shown potential as a novel anti-TB agent. This review aims to provide an overview of the therapeutic prospects of UA against MTB, with a particular emphasis on in silico, in vitro, and in vivo studies. Various mechanisms of action of UA against MTB are briefly recapped from in silico studies, such as enoyl acyl carrier protein reductase inhibitors, FadA5 (Acetyl-CoA acetyltransferase) inhibitors, tuberculosinyl adenosine transferase inhibitors, and small heat shock protein 16.3 inhibitor. The potential of UA to overcome drug resistance and its synergistic effects with existing antituberculosis drugs are briefly explained from in vitro studies using a variety of methods, such as Microplate Alamar Blue Assay, Mycobacteria Growth Indicator Tube 960 and Resazurin Assays, morphological change evaluation using transmission electron microscopy, and in vivo studies using BALB/C infected with multi drug resistant clinical isolates. Besides its promising mechanism as an antituberculosis drug, its complex chemical composition, limited availability and supply, and lack of intellectual property are also reviewed as those are the most frequently occurring challenges that need to be addressed for the successful development of UA as novel anti-TB agent.

Oleanolic acid: an antimycobacterial component of Syzygium aromaticum L. and inhibitor of efflux mediated drug resistance

Oleanolic acid (OA) was isolated from Syzygium aromaticum L. buds, and structurally characterised using different spectroscopic techniques; MS, IR,1H/13C-NMR and 2D NMR experiments. The antimycobacterial activity according to a resazurin microtiter assay (REMA) showed important inhibitory effect of OA on the virulent H37Rv strain, with the lowest minimum concentration of 50 µg/mL, compared to other fractions. Molecular docking of OA with BacA drug efflux pump resulted in good binding affinity of hydrophobic interaction type. Therefore, OA could contribute to the antimycobacterial action of clove buds, and has potential as an efflux pump inhibitor. Further studies are required on its use to combat multidrug resistant strains.

Natural products in anti-tuberculosis host-directed therapy

Given that the disease progression of tuberculosis (TB) is primarily related to the host's immune status, it has been gradually realized that chemotherapy that targets the bacteria may never, on its own, wholly eradicate Mycobacterium tuberculosis, the causative agent of TB. The concept of host-directed therapy (HDT) with immune adjuvants has emerged. HDT could potentially interfere with infection and colonization by the pathogens, enhance the protective immune responses of hosts, suppress the overwhelming inflammatory responses, and help to attain a state of homeostasis that favors treatment efficacy. However, the HDT drugs currently being assessed in combination with anti-TB chemotherapy still face the dilemmas arising from side effects and high costs. Natural products are well suited to compensate for these shortcomings by having gentle modulatory effects on the host immune responses with less immunopathological damage at a lower cost. In this review, we first summarize the profiles of anti-TB immunology and the characteristics of HDT. Then, we focus on the rationale and challenges of developing and implementing natural products-based HDT. A succinct report of the medications currently being evaluated in clinical trials and preclinical studies is provided. This review aims to promote target-based screening and accelerate novel TB drug discovery.

Necroptosis in Pneumonia: Therapeutic Strategies and Future Perspectives

Pneumonia remains a major global health challenge, necessitating the development of effective therapeutic approaches. Recently, necroptosis, a regulated form of cell death, has garnered attention in the fields of pharmacology and immunology for its role in the pathogenesis of pneumonia. Characterized by cell death and inflammatory responses, necroptosis is a key mechanism contributing to tissue damage and immune dysregulation in various diseases, including pneumonia. This review comprehensively analyzes the role of necroptosis in pneumonia and explores potential pharmacological interventions targeting this cell death pathway. Moreover, we highlight the intricate interplay between necroptosis and immune responses in pneumonia, revealing a bidirectional relationship between necrotic cell death and inflammatory signaling. Importantly, we assess current therapeutic strategies modulating necroptosis, encompassing synthetic inhibitors, natural products, and other drugs targeting key components of the programmed necrosis pathway. The article also discusses challenges and future directions in targeting programmed necrosis for pneumonia treatment, proposing novel therapeutic strategies that combine antibiotics with necroptosis inhibitors. This review underscores the importance of understanding necroptosis in pneumonia and highlights the potential of pharmacological interventions to mitigate tissue damage and restore immune homeostasis in this devastating respiratory infection.

Ursolic Acid Promotes Autophagy by Inhibiting Akt/mTOR and TNF-α/TNFR1 Signaling Pathways to Alleviate Pyroptosis and Necroptosis in Mycobacterium tuberculosis-Infected Macrophages

As a lethal infectious disease, tuberculosis (TB) is caused by Mycobacterium tuberculosis (Mtb). Its complex pathophysiological process limits the effectiveness of many clinical treatments. By regulating host cell death, Mtb manipulates macrophages, the first line of defense against invading pathogens, to evade host immunity and promote the spread of bacteria and intracellular inflammatory substances to neighboring cells, resulting in widespread chronic inflammation and persistent lung damage. Autophagy, a metabolic pathway by which cells protect themselves, has been shown to fight intracellular microorganisms, such as Mtb, and they also play a crucial role in regulating cell survival and death. Therefore, host-directed therapy (HDT) based on antimicrobial and anti-inflammatory interventions is a pivotal adjunct to current TB treatment, enhancing anti-TB efficacy. In the present study, we showed that a secondary plant metabolite, ursolic acid (UA), inhibited Mtb-induced pyroptosis and necroptosis of macrophages. In addition, UA induced macrophage autophagy and enhanced intracellular killing of Mtb. To investigate the underlying molecular mechanisms, we explored the signaling pathways associated with autophagy as well as cell death. The results showed that UA could synergistically inhibit the Akt/mTOR and TNF-α/TNFR1 signaling pathways and promote autophagy, thus achieving its regulatory effects on pyroptosis and necroptosis of macrophages. Collectively, UA could be a potential adjuvant drug for host-targeted anti-TB therapy, as it could effectively inhibit pyroptosis and necroptosis of macrophages and counteract the excessive inflammatory response caused by Mtb-infected macrophages via modulating the host immune response, potentially improving clinical outcomes.

Deciphering the emerging role of phytocompounds: Implications in the management of drug-resistant tuberculosis and ATDs-induced hepatic damage

Tuberculosis is a disease of poverty, discrimination, and socioeconomic burden. Epidemiological studies suggest that the mortality and incidence of tuberculosis are unacceptably higher worldwide. Genomic mutations in embCAB, embR, katG, inhA, ahpC, rpoB, pncA, rrs, rpsL, gyrA, gyrB, and ethR contribute to drug resistance reducing the susceptibility of Mycobacterium tuberculosis to many antibiotics. Additionally, treating tuberculosis with antibiotics also poses a serious risk of hepatotoxicity in the patient's body. Emerging data on drug-induced liver injury showed that anti-tuberculosis drugs remarkably altered levels of hepatotoxicity biomarkers. The review is an attempt to explore the anti-mycobacterial potential of selected, commonly available, and well-known phytocompounds and extracts of medicinal plants against strains of Mycobacterium tuberculosis. Many studies have demonstrated that phytocompounds such as flavonoids, alkaloids, terpenoids, and phenolic compounds have antibacterial action against Mycobacterium species, inhibiting the bacteria's growth and replication, and sometimes, causing cell death. Phytocompounds act by disrupting bacterial cell walls and membranes, reducing enzyme activity, and interfering with essential metabolic processes. The combination of these processes reduces the overall survivability of the bacteria. Moreover, several phytochemicals have synergistic effects with antibiotics routinely used to treat TB, improving their efficacy and decreasing the risk of resistance development. Interestingly, phytocompounds have been presented to reduce isoniazid- and ethambutol-induced hepatotoxicity by reversing serum levels of AST, ALP, ALT, bilirubin, MDA, urea, creatinine, and albumin to their normal range, leading to attenuation of inflammation and hepatic necrosis. As a result, phytochemicals represent a promising field of research for the development of new TB medicines.

Effect directed analysis of bioactive compounds in leaf extracts from two Salvia species by High-performance thin-layer chromatography

Extracts of two Salvia species, Salvia apiana (white sage) and Salvia officinalis (common sage) were screened for phytoconstituents with the ability to act as antidiabetic, cognitive enhancing, or antimicrobial agents, by hyphenation of high-performance thin-layer chromatography with enzymatic and microbial effect directed assays. Two bioactive zones with α-amylase inhibition (zone 1 and zone 2), 3 zones for acetylcholinesterase inhibition (zones 3, 4 and 5), and two zones for antimicrobial activity (zones 4 and 5) were detected. The compounds from the five bioactive zones were initially identified by coelution with standards and comparing the R_F values of standards to the bioautograms. Identity was confirmed with ATR-FTIR spectra of the isolated compounds from the bioactive zones. A significantly higher α-amylase and acetylcholinesterase inhibition of S. apiana leaf extract was associated with a higher flavonoid and diterpenoid content. Fermented S. officinalis extract exhibited a significantly higher ability to inhibit α-amylase compared to other non-fermented extracts from this species, due to increased extraction of flavonoids. The ATR-FTIR spectra of 2 zones with α-amylase inhibition, indicated that flavonoids and phenolic acids were responsible for α-amylase inhibition. Multiple zones of acetylcholinesterase inhibition were related to the presence of phenolic abietane diterpenoids and triterpenoid acids. The presence of abietane diterpenoids and triterpenoid acids was also found responsible for the mild antimicrobial activity. Flash chromatography was used to isolate sufficient amounts of bioactive compounds for further characterisation via NMR and MS spectroscopy. Five compounds were assigned to the zones where bioactivity was observed: cirsimaritin (zone 1), a caffeic acid polymer (zone 2), 16-hydroxyrosmanol (zone 3), 16-hydroxycarnosic acid (zone 4), oleanolic and ursolic acids (zone 5).

Method development and validation for quantification of six bioactive compounds (andrographolide, columbin, piperine, gallic, paracoumaric and oleanolic acids) by HPTLC

OBJECTIVES

During the spread of pandemic diseases, immunity boosting herbal drugs are taken as a preventive medicine. Kapacurak Kuṭinīr Cūraṇam is a Siddha drug used for flu like viral infections, cold and fever. Developing an analytical method to estimate the content of active phytoconstituents in such antiviral immune boosting drug will be useful in the phyto pharmaceutical industry.

METHODS

A precise, reliable and sensitive ordinary phase high performance thin layer chromatography (HPTLC) method has been developed and validated for identification and simultaneous estimation of six bioactive components namely like andrographolide, columbin, gallic acid, ρ-coumaric acid, piperine and oleanolic acid from any Indian traditional medicine, medicinal plant, drugs and food materials etc. The separation was achieved on silica gel 60F₂₅₄ TLC plates using toluene: ethyl acetate: formic acid (7:3:0.5, v/v) as mobile phase. The gallic acid, ρ-coumaric acid, piperine markers were estimated using the densitometric scanning in absorption mode at 254 nm. The densitometric scanning was done after derivatization (vanillin-sulphuric acid reagent) at λ=520 nm for andrographolide, columbin and oleanolic acid.

RESULTS

The linear regression analysis data for the calibration plots showed a correlation coefficient in the concentration range 1-5 μg per band for the bioactive markers with respect to area. The method was validated for accuracy, precision, limit of detection (LOD), and quantitation of limit (LOQ).

CONCLUSIONS

Developed method was accurate, precise and fast to ensure the quality of Kapacurak Kuṭinīr Cūraṇam.

Fractionation and Characterization of Triterpenoids from Vaccinium vitis-idaea L. Cuticular Waxes and Their Potential as Anticancer Agents

Fruit and leaf cuticular waxes are valuable source materials for the isolation of triterpenoids that can be applied as natural antioxidants and anticancer agents. The present study aimed at the semi-preparative fractionation of triterpenoids from cuticular wax extracts of Vaccinium vitis-idaea L. (lingonberry) leaves and fruits and the evaluation of their cytotoxic potential. Qualitative and quantitative characterization of obtained extracts and triterpenoid fractions was performed using HPLC-PDA method, followed by complementary analysis by GC-MS. For each fraction, cytotoxic activities towards the human colon adenocarcinoma cell line (HT-29), malignant melanoma cell line (IGR39), clear renal carcinoma cell line (CaKi-1), and normal endothelial cells (EC) were determined using MTT assay. Furthermore, the effect of the most promising samples on cancer spheroid growth and viability was examined. This study allowed us to confirm that particular triterpenoid mixtures from lingonberry waxes may possess stronger cytotoxic activities than crude unpurified extracts. Fractions containing triterpenoid acids plus fernenol, complexes of oleanolic:ursolic acids, and erythrodiol:uvaol were found to be the most potent therapeutic candidates in the management of cancer diseases. The specificity of cuticular wax extracts of lingonberry leaves and fruits, leading to different purity and anticancer potential of obtained counterpart fractions, was also enclosed. These findings contribute to the profitable utilization of lingonberry cuticular waxes and provide considerable insights into the anticancer effects of particular triterpenoids and pharmacological interactions.

Targeting dormant phenotype acquired mycobacteria using natural products by exploring its important targets: In vitro and in silico studies

The dormant phenotype of Mycobacterium tuberculosis that develops during infection poses a major challenge in disease treatment, since these bacilli show tolerance to front-line drugs. An in vitro hypoxia dormancy model was established, which produced phenotypically dormant Mycobacterium smegmatis after prolonged incubation under conditions of low oxygen, low pH, and nutrient limitation. Bacilli in this model displayed the classical dormancy characters, including loss of acid fastness, altered morphology, and, most importantly, tolerance to front-line drugs. The dormant form of M. smegmatis was treated with drugs and phytomolecules. Three phytomolecules exhibited activity against dormant bacilli, as shown by lack of regrowth in solid and liquid media. Further investigation of dormancy-active hits was carried out using in silico approaches to understand the druggable targets of these phytomolecules in dormant bacilli. For this study, molecular docking, molecular dynamics simulations (MDS), and molecular mechanics-generalized born solvent accessibility (MM-GBSA)-based binding energy (ΔG_bind) calculations were performed. Five different targets, namely, isocitrate lyase (ICL), GMP synthase, LuxR, DosR, and serine/threonine protein kinase (STPK), from M. smegmatis and M. tuberculosis were studied in details. DosR and STPK were found to be the common targets in both the species that were more prone to the phytomolecules. The standard DosR inhibitor, HC104A, showed a lower dock score and binding energy of -4.27 and -34.50 kcal/mol, respectively, compared to the natural products under study. The phytomolecule, icariin, showed better docking score (dock score = -5.92 kcal/mol with and binding energy ΔG_bind= -52.96 kcal/mol) with DosR compared to known DosR inhibitor, HC104A (dock score = -4.27 kcal/mol and binding energy ΔG_bind = -34.50 kcal/mol). Similarly, the known STPK inhibitor MRCT67127 showed a lower dock score and binding energy of -4.25 and -29.43 kcal/mol, respectively, compared to the phytomolecule, icariin (dock score = -5.74 kcal/mol and ΔG_bind= -43.41 kcal/mol). These compounds might ultimately lead to new therapeutics or may be useful as adjuvants to the first-line drugs to reduce the lengthy anti-TB therapy in the future.

Targeted delivery of ursolic acid and oleanolic acid to lungs in the form of an inhaler for the management of tuberculosis: Pharmacokinetic and toxicity assessment

INTRODUCTION

Ursolic acid (UA) and oleanolic acid (OA) are triterpenoids. They are used to treat numerous diseases, including tuberculosis. Combinations of these drugs provide new insight into the management of tuberculosis. The major obstacle is the effective delivery of these drugs to the lungs, which are mainly affected due to M. tuberculosis. A metered-dose inhaler (MDI) was developed to address this issue containing UA and OA, followed by in-vitro and in-vivo evaluation.

METHODS

In the present study, MDI formulation was prepared by incorporating UA and OA at the dose level of 120 μg/ml in each actuation. In-vitro evaluation of this MDI formulation was performed to ensure its suitability to deliver UA and OA preciously. With prior approval of IAEC, a pharmacokinetic and acute inhalation toxicity study was conducted using MDI on Wistar rats.

RESULTS

The pharmacokinetic study showed an increased biological half-life of UA (9.23±0.104 h) and OA (8.93±0.166 h) in combination therapy. In-vivo toxicity study demonstrated no adverse effects on body weight and vital organs in the treatment group compared with the control group. Histopathology examination of these essential organs showed no abnormalities. Mild alternation in the biochemical and hematological parameters was observed. However, these alterations did not affect the overall health of the animals.

CONCLUSION

The present study documents a detailed study for the safety and pharmacokinetics of UA and OA in-vivo for their advanced application in tuberculosis disease.

Modulating macrophage function to reinforce host innate resistance against Mycobacterium avium complex infection

Mycobacterium avium complex (MAC) is the main causative agent of infectious diseases in humans among nontuberculous mycobacteria (NTM) that are ubiquitous organisms found in environmental media such as soil as well as in domestic and natural waters. MAC is a primary causative agent of NTM-lung disease that threaten immunocompromised or structural lung disease patients. The incidence and the prevalence of M. tuberculosis infection have been reduced, while MAC infections and mortality rates have increased, making it a cause of global health concern. The emergence of drug resistance and the side effects of long-term drug use have led to a poor outcome of treatment regimens against MAC infections. Therefore, the development of host-directed therapy (HDT) has recently gained interest, aiming to accelerate mycobacterial clearance and reversing lung damage by employing the immune system using a novel adjuvant strategy to improve the clinical outcome of MAC infection. Therefore, in this review, we discuss the innate immune responses that contribute to MAC infection focusing on macrophages, chief innate immune cells, and host susceptibility factors in patients. We also discuss potential HDTs that can act on the signaling pathway of macrophages, thereby contributing to antimycobacterial activity as a part of the innate immune response during MAC infection. Furthermore, this review provides new insights into MAC infection control that modulates and enhances macrophage function, promoting host antimicrobial activity in response to potential HDTs and thus presenting a deeper understanding of the interactions between macrophages and MACs during infection.

Recent advances in medicinal chemistry of oleanolic acid derivatives

Oleanolic acid (OA), a ubiquitous pentacyclic oleanane-type triterpene isolated from edible and medicinal plants, exhibits a wide spectrum of pharmacological activities and tremendous therapeutic potential. However, the undesirable pharmacokinetic properties limit its application and development. Numerous researches on structural modifications of OA have been carried out to overcome this limitation and improve its pharmacokinetic and therapeutic properties. This review aims to compile and summarize the recent progresses in the medicinal chemistry of OA derivatives, especially on structure-activity relationship in the last few years (2010-2021). It gives insights into the rational design of bioactive derivatives from OA scaffold as promising therapeutic agents.

Secondary Metabolites with Biomedical Applications from Plants of the Sarraceniaceae Family

Carnivorous plants have fascinated researchers and hobbyists for centuries because of their mode of nutrition which is unlike that of other plants. They are able to produce bioactive compounds used to attract, capture and digest prey but also as a defense mechanism against microorganisms and free radicals. The main purpose of this review is to provide an overview of the secondary metabolites with significant biological activity found in the Sarraceniaceae family. The review also underlines the necessity of future studies for the biochemical characterization of the less investigated species. Darlingtonia, Heliamphora and Sarracenia plants are rich in compounds with potential pharmaceutical and medical uses. These belong to several classes such as flavonoids, with flavonol glycosides being the most abundant, monoterpenes, triterpenes, sesquiterpenes, fatty acids, alkaloids and others. Some of them are well characterized in terms of chemical properties and biological activity and have widespread commercial applications. The review also discusses biological activity of whole extracts and commercially available products derived from Sarraceniaceae plants. In conclusion, this review underscores that Sarraceniaceae species contain numerous substances with the potential to advance health. Future perspectives should focus on the discovery of new molecules and increasing the production of known compounds using biotechnological methods.

State-of-the-Art and Opportunities for Bioactive Pentacyclic Triterpenes from Native Mexican Plants

Native Mexican plants are a wide source of bioactive compounds such as pentacyclic triterpenes. Pentacyclic triterpenes biosynthesized through the mevalonate (MVA) and the 2-C-methyl-D-erythritol-phosphate (MEP) metabolic pathways are highlighted by their diverse biological activity. Compounds belonging to the oleanane, ursane, and lupane groups have been identified in about 33 Mexican plants, located geographically in the southwest of Mexico. The works addressing these findings have reported 45 compounds that mainly show antimicrobial activity, followed by anti-inflammatory, cytotoxic, anxiolytic, hypoglycemic, and growth-stimulating or allelopathic activities. Extraction by maceration and Soxhlet with organic solvents and consecutive chromatography of silica gel have been used for their whole or partial purification. Nanoparticles and nanoemulsions are the vehicles used in Mexican formulations for drug delivery of the pentacyclic triterpenes until now. Sustainable extraction, formulation, regulation, isolation, characterization, and bioassay facilities are areas of opportunity in pentacyclic triterpenes research in Mexico while the presence of plant and human resources and traditional knowledge are strengths. The present review discusses the generalities of the pentacyclic triterpene (definition, biogenic classification, and biosynthesis), a summary of the last two decades of research on the compounds identified and their evaluated bioactivity, the generalities about the extraction and purification methods used, drug delivery aspects, and a critical analysis of the advantages and limitations of research carried out in this way.

Advances in adjunct therapy against tuberculosis: Deciphering the emerging role of phytochemicals

Eastern countries are a major source of medicinal plants, which set up a rich source of ethnopharmacologically known medicines used in the treatment of various diseases. These traditional medicines have been known as complementary, alternative, or nonconventional therapy across globe for ages. Tuberculosis (TB) poses a huge global burden and leads to maximum number of deaths due to an infectious agent. Treatment of TB using Directly Observed Treatment Short-course (DOTS) therapy comprises multiple antibiotics is quite lengthy and causes serious side-effects in different organs. The length of the TB treatment leads to withdrawal from the patients, which paves the way for the emergence of drug resistance in the bacterial population. These concerns related to therapy need serious and immediate interventions. Traditional medicines using phytochemicals has shown to provide tremendous potential in TB treatment, mainly in the eradication of Mycobacterium tuberculosis (M.tb), increasing natural immunity, and managing the side effects of anti-TB drugs. This review describes the antituberculosis potential of selected ethnopharmacologically important phytochemicals as potential immune-modulator and as an adjunct-therapy in TB. This review will be a useful reference for researchers working on ethnopharmacology and will open the door for the discovery of novel agents as an adjunct-therapy to tuberculosis.

Efficacy of Ursolic Acid-Enriched Water-Soluble and Not Cytotoxic Nanoparticles against Enterococci

Ursolic acid (UA), a pentacyclic triterpenoid acid found in many medicinal plants and aromas, is known for its antibacterial effects against multi-drug-resistant (MDR) Gram-positive bacteria, which seriously threaten human health. Unfortunately, UA water-insolubility, low bioavailability, and systemic toxicity limit the possibilities of its application in vivo. Consequently, the beneficial activities of UA observed in vitro lose their potential clinical relevance unless water-soluble, not cytotoxic UA formulations are developed. With a nano-technologic approach, we have recently prepared water-soluble UA-loaded dendrimer nanoparticles (UA-G4K NPs) non-cytotoxic on HeLa cells, with promising physicochemical properties for their clinical applications. In this work, with the aim of developing a new antibacterial agent based on UA, UA-G4K has been tested on different strains of the Enterococcus genus, including marine isolates, toward which UA-G4K has shown minimum inhibitory concentrations (MICs) very low (0.5-4.3 µM), regardless of their resistance to antibiotics. Time-kill experiments, in addition to confirming the previously reported bactericidal activity of UA against E. faecium, also established it for UA-G4K. Furthermore, cytotoxicity experiments on human keratinocytes revealed that nanomanipulation of UA significantly reduced the cytotoxicity of UA, providing UA-G4K NPs with very high LD₅₀ (96.4 µM) and selectivity indices, which were in the range 22.4-192.8, depending on the enterococcal strain tested. Due to its physicochemical and biological properties, UA-G4K could be seriously evaluated as a novel oral-administrable therapeutic option for tackling difficult-to-treat enterococcal infections.

Therapeutic Potential of Ursolic Acid in Cancer and Diabetic Neuropathy Diseases

Ursolic acid (UA) is a pentacyclic triterpenoid frequently found in medicinal herbs and plants, having numerous pharmacological effects. UA and its analogs treat multiple diseases, including cancer, diabetic neuropathy, and inflammatory diseases. UA inhibits cancer proliferation, metastasis, angiogenesis, and induced cell death, scavenging free radicals and triggering numerous anti- and pro-apoptotic proteins. The biochemistry of UA has been examined broadly based on the literature, with alterations frequently having been prepared on positions C-3 (hydroxyl), C12-C13 (double bonds), and C-28 (carboxylic acid), leading to several UA derivatives with increased potency, bioavailability and water solubility. UA could be used as a protective agent to counter neural dysfunction via anti-oxidant and anti-inflammatory effects. It is a potential therapeutic drug implicated in the treatment of cancer and diabetic complications diseases provide novel machinery to the anti-inflammatory properties of UA. The pharmacological efficiency of UA is exhibited by the therapeutic theory of one-drug → several targets → one/multiple diseases. Hence, UA shows promising therapeutic potential for cancer and diabetic neuropathy diseases. This review aims to discuss mechanistic insights into promising beneficial effects of UA. We further explained the pharmacological aspects, clinical trials, and potential limitations of UA for the management of cancer and diabetic neuropathy diseases.

Bioprospecting for antituberculosis natural products – A review

There has been an increase in the reported cases of tuberculosis, a disease caused by Mycobacterium tuberculosis, which is still currently affecting most of the world’s population, especially in resource-limited countries. The search for novel antitubercular chemotherapeutics from underexplored natural sources is therefore of paramount importance. The renewed interest in studies related to natural products, driven partly by the growing incidence of MDR-TB, has increased the prospects of discovering new antitubercular drug leads. This is because most of the currently available chemotherapeutics such as rifampicin and capreomycin used in the treatment of TB were derived from natural products, which are proven to be an abundant source of novel drugs used to treat many diseases. To meet the global need for novel antibiotics from natural sources, various strategies for high-throughput screening have been designed and implemented. This review highlights the current antitubercular drug discovery strategies from natural sources.

Convenient Tuning of the Elasticity of Self-Assembled Nano-Sized Triterpenoids to Regulate Their Biological Activities

The impact of the mechanical properties of nanomedicines on their biological functions remains elusive due to the difficulty in tuning the elasticity of the vehicles without changing chemistry. Herein, we report the fabrication of elasticity-tunable self-assembled oleanolic acid (OA) nanoconstructs in an antiparallel zigzag manner and develop rigid nanoparticles (OA-NP) and flexible nanogels (OA-NG) as model systems to decipher the elasticity-biofunction relationship. OA-NG demonstrate less endocytosis and enhanced lysosome escape with deformation compared to OA-NP. Further in vitro and in vivo experiments show the active permeation of OA-NG into the interior of tumor with enhanced antitumor efficacy accompanied by decreased collagen production and eight- to tenfold immune cell infiltration. This study not only presents a facile and green strategy to develop flexible OA-NG for effective cancer treatment but also uncovers the crucial role of elasticity in regulating biological activity, which may provide reference for precise design of efficient nanomedicines.

Traditional Medicinal Plants as a Source of Antituberculosis Drugs: A System Review

Medicinal plants are the chief components in the different oriental formulations in different traditional medical systems worldwide. As a thriving source of medicine, the medicinal plants with antituberculosis (TB) properties inspire the pharmacists to develop new drugs based on their active components or semimetabolites. In the present review, the anti-TB medicinal plants were screened from the scientific literatures, based on the botanical classification and the anti-TB activity. The obtained anti-TB medicinal plants were categorized into three different categories, viz., 159 plants critically examined with a total 335 isolated compounds, 131 plants with their crude extracts showing anti-TB activity, and 27 plants in literature with the prescribed formula by the traditional healers. Our systemic analysis on the medicinal plants can assist the discovery of novel and more efficacious anti-TB drugs.

The Introduction of Hydrazone, Hydrazide, or Azepane Moieties to the Triterpenoid Core Enhances an Activity Against M. tuberculosis

BACKGROUND

Triterpenoids exhibit a wide spectrum of antimicrobial activity.

OBJECTIVE

The objective of this study was to synthesize a series of nitrogen derivatives based on lupane, oleanane, and ursane triterpenoids with high antitubercular activity.

METHODS

Isonicotinoylhydrazones were prepared via the reaction of 3-oxotriterpenic acids or betulonic aldehyde with isoniazid (INH) in yields of 54-72%. N-Acylation of betulonic or azepanobetulinic acids led to lupane C28 hydrazides and dihydrazides. The derivatives were evaluated for their in vitro antimycobacterial activities against Mycobacterium tuberculosis (MTB) H37RV and single-drug resistance (SDR)-TB in the National Institute of Allergy and Infectious Diseases, USA. Molecular docking was performed to evaluate the possible binding modes of investigated compounds in the active site of Diterpene synthase (Rv3378c).

RESULTS

The obtained compounds are represented by C3 or C28 conjugates with hydrazine hydrate or INH. Some compounds demonstrated from high minimum inhibitory concentration (MIC ≤ 10 μg/mL) to excellent (MICs from 0.19 to 1.25 μg/mL) activity against MTB H37RV. Two lupane conjugates with INH were the leading compounds against MTB H37RV and some SDR-strains with MICs ranged from 0.19 to 1.70 μg/mL. Molecular docking of active compounds to diterpene synthase showed that these moieties accommodate the active site of the enzyme.

CONCLUSION

It was revealed that the conjugation of lupanes with INH at C3 is more effective than at C28 and the lupane skeleton is preferable among oleanane and ursane types. The replacement of native hexacarbocyclic A ring to seven-member azepane ring is favorably for inhibition of both MTB H37RV and SDR-strains. These data could possibly mean that the antitubercular activity against INH-resistant strains (INH-R) came from both triterpenoid and isoniazid parts of the hybrid molecules. Azepanobetulin showed the highest activity against both INH-R strains in comparison with other triterpenoids and INH. Thus, the introduction of hydrazone, hydrazide (dihydrazide), or azepane moieties into the triterpenoid core is a promising way for the development of new anti-tubercular agents.

Valorization of Bio-Residues from the Processing of Main Portuguese Fruit Crops: From Discarded Waste to Health Promoting Compounds

Food processing generates a large amount of bio-residues, which have become the focus of different studies aimed at valorizing this low-cost source of bioactive compounds. High fruit consumption is associated with beneficial health effects and, therefore, bio-waste and its constituents arouse therapeutic interest. The present work focuses on the main Portuguese fruit crops and revises (i) the chemical constituents of apple, orange, and pear pomace as potential sources of functional/bioactive compounds; (ii) the bioactive evidence and potential therapeutic use of bio-waste generated in the processing of the main Portuguese fruit crops; and (iii) potential applications in the food, nutraceutical, pharmaceutical, and cosmetics industries. The current evidence of the effect of these bio-residues as antioxidant, anti-inflammatory, and antimicrobial agents is also summarized. Conclusions of the revised data are that these bio-wastes hold great potential to be employed in specific nutritional and pharmaceutical applications.

Mexican Plants and Derivates Compounds as Alternative for Inflammatory and Neuropathic Pain Treatment-A Review

Despite the availability of many anti-pain drugs, in the form of NSAIDs, steroids, gabapentinoids, opioids, and antidepressants, in this study we address the natural compounds belonging to the group of Mexican medicinal plants or "Mexican folk medicine", used for pain management in Mexico. Our interest in this subject is due to the growing idea that "natural is harmless" and to the large number of side effects exhibited in pharmacotherapy. The objective of this review was to document the scientific evidence about Mexican medicinal plants and their derivatives used for inflammatory and neuropathic pain treatment, as well as the mechanisms of action implicated in their antinociceptive effects, their possible adverse effects, and the main pharmacological aspects of each plant or compound. Our data review suggested that most studies on Mexican medicinal plants have used inflammatory experimental models for testing. The anti-pain properties exerted by medicinal plants lack adverse effects, and their toxicological assays report that they are safe to consume; therefore, more studies should be performed on preclinical neuropathic pain models. Moreover, there is no convincing evidence about the possible mechanisms of action involved in the anti-pain properties exerted by Mexican plants. Therefore, the isolation and pharmacological characterization of these plant derivatives' compounds will be important in the design of future preclinical studies.

Antibiotics: Conventional Therapy and Natural Compounds with Antibacterial Activity-A Pharmaco-Toxicological Screening

Antibiotics are considered as a cornerstone of modern medicine and their discovery offers the resolution to the infectious diseases problem. However, the excessive use of antibiotics worldwide has generated a critical public health issue and the bacterial resistance correlated with antibiotics inefficiency is still unsolved. Finding novel therapeutic approaches to overcome bacterial resistance is imperative, and natural compounds with antibacterial effects could be considered a promising option. The role played by antibiotics in tumorigenesis and their interrelation with the microbiota are still debatable and are far from being elucidated. Thus, the present manuscript offers a global perspective on antibiotics in terms of evolution from a historical perspective with an emphasis on the main classes of antibiotics and their adverse effects. It also highlights the connection between antibiotics and microbiota, focusing on the dual role played by antibiotics in tumorigenesis. In addition, using the natural compounds with antibacterial properties as potential alternatives for the classical antibiotic therapy is discussed.

Ethnobotany and the Role of Plant Natural Products in Antibiotic Drug Discovery

The crisis of antibiotic resistance necessitates creative and innovative approaches, from chemical identification and analysis to the assessment of bioactivity. Plant natural products (NPs) represent a promising source of antibacterial lead compounds that could help fill the drug discovery pipeline in response to the growing antibiotic resistance crisis. The major strength of plant NPs lies in their rich and unique chemodiversity, their worldwide distribution and ease of access, their various antibacterial modes of action, and the proven clinical effectiveness of plant extracts from which they are isolated. While many studies have tried to summarize NPs with antibacterial activities, a comprehensive review with rigorous selection criteria has never been performed. In this work, the literature from 2012 to 2019 was systematically reviewed to highlight plant-derived compounds with antibacterial activity by focusing on their growth inhibitory activity. A total of 459 compounds are included in this Review, of which 50.8% are phenolic derivatives, 26.6% are terpenoids, 5.7% are alkaloids, and 17% are classified as other metabolites. A selection of 183 compounds is further discussed regarding their antibacterial activity, biosynthesis, structure-activity relationship, mechanism of action, and potential as antibiotics. Emerging trends in the field of antibacterial drug discovery from plants are also discussed. This Review brings to the forefront key findings on the antibacterial potential of plant NPs for consideration in future antibiotic discovery and development efforts.

Improved Pharmacokinetic Characteristics of Ursolic Acid in Rats Following Intratracheal Instillation and Nose-Only Inhalation Exposure

Ursolic acid (UA) is a common pentacyclic triterpene phytochemical with various pharmacological activities. However, UA is classified as a class IV drug in BCS system and its development as an oral drug is limited. Pulmonary delivery is an effective way to improve the bioavailability of drugs with low absorption. In this study, the differences in pharmacokinetic behaviors of UA after pulmonary and oral administration was explored in rats. Compared with oral administration, the plasma concentration of UA increased rapidly after pulmonary administration, and the bioavailability increased about 80 times. UA instantly accumulated in the lungs after pulmonary administration, and the pulmonary AUC0-t/dose increased by 114 times compared to oral dosing. Incubation experiments showed that the metabolism of UA in rat lung microsomes was significantly reduced compared with that in liver microsomes, in which the clearance rate of phase I and phase II metabolism was reduced by 14.7 times and 1.4 times respectively. These results indicated that pulmonary administration could improve the bioavailability of UA and reduce its metabolism. This study not only provides a preferable route of administration for the application of UA but also offers new insights for the development of phytochemical drug candidates with poor pharmacokinetic properties.

Molecular Docking Suggests the Targets of Anti-Mycobacterial Natural Products

Tuberculosis (TB) is a major global threat, mostly due to the development of antibiotic-resistant forms of Mycobacterium tuberculosis, the causal agent of the disease. Driven by the pressing need for new anti-mycobacterial agents several natural products (NPs) have been shown to have in vitro activities against M. tuberculosis. The utility of any NP as a drug lead is augmented when the anti-mycobacterial target(s) is unknown. To suggest these, we used a molecular reverse docking approach to predict the interactions of 53 selected anti-mycobacterial NPs against known "druggable" mycobacterial targets ClpP1P2, DprE1, InhA, KasA, PanK, PknB and Pks13. The docking scores/binding free energies were predicted and calculated using AutoDock Vina along with physicochemical and structural properties of the NPs, using PaDEL descriptors. These were compared to the established inhibitor (control) drugs for each mycobacterial target. The specific interactions of the bisbenzylisoquinoline alkaloids 2-nortiliacorinine, tiliacorine and 13'-bromotiliacorinine against the targets PknB and DprE1 (-11.4, -10.9 and -9.8 kcal·mol-1; -12.7, -10.9 and -10.3 kcal·mol-1, respectively) and the lignan α-cubebin and Pks13 (-11.0 kcal·mol-1) had significantly superior docking scores compared to controls. Our approach can be used to suggest predicted targets for the NP to be validated experimentally, but these in silico steps are likely to facilitate drug optimization.

Anti-mycobacterial and anti-inflammatory activity of restinga plants: a dual approach in searching for new drugs to treat severe tuberculosis

Abstract Tuberculosis (TB) still constitutes a threat to public health in various regions of the world. The existing treatment is long and has many side effects. The need to identify new anti-TB compounds and also adjuvants to control exacerbated inflammation in severe TB cases is relevant. Therefore, the objective of this study was to evaluate the anti-mycobacterial activity of extracts and fractions in vitro from plant species collected in the Restinga of Jurubatiba, in Rio de Janeiro state, Brazil. In addition, to verify their immunomodulatory action and cytotoxicity on macrophages. The dichloromethane fraction of Kielmeyera membranacea and Eremanthus crotonoides showed the lowest MIC50 against Mycobacterium bovis BCG (0.95 ± 1.08 and 2.17 ± 1.11 μg/mL, respectively) and M. tuberculosis H37Rv (4.38 ± 1.19 and 15.28 ± 1.21 μg/mL, respectively). They were also able to inhibit the NO and TNF-α production in LPS-stimulated macrophages, without being toxic to cells. Using gas chromatography analysis coupled with mass spectrometer it was possible to suggest the presence of fatty acids and terpenes in the most promising fractions. Those compounds have been described for their anti-mycobacterial activity. These results have enabled identifying Kielmeyera membranacea and Eremanthus crotonoides as the most promising studied species in searching for new anti-TB compounds with dual activity.

A Review on Recent Trends in Green Synthesis of Gold Nanoparticles for Tuberculosis

Tuberculosis (TB) is a contagious disease that has affected mankind. The anti-TB treatment has been used from ancient times to control symptoms of this disease but these medications produced some serious side effects. Herbal products have been successfully used for the treatment of TB. Gold is the most biocompatible metal among all available for biomedical purposes so Gold nanoparticles (GNPs) have sought attention as an attractive biosynthesized drug to be studied in recent years for bioscience research. GNPs are used as better catalysts and due to unique small size, physical resemblance to physiological molecules, biocompatibility and non-cytotoxicity extensively used for various applications including drug and gene delivery. Greenly synthesized GNPs have much more potential in different fields because phytoconstituents used in GNP synthesis itself act as reducing and capping agents and produced more stabilized GNPs. This review is devoted to a discussion on GNPs synthesis with herbs for TB. The main focus is on the role of the natural plant bio-molecules involved in the bioreduction of metal salts during the GNPs synthesis with phytoconstituents used as antitubercular agents.

Discovery of Gut Bacteria Specific to Alzheimer's Associated Diseases is a Clue to Understanding Disease Etiology: Meta-Analysis of Population-Based Data on Human Gut Metagenomics and Metabolomics

Alzheimer's disease (AD)-associated sequence (ADAS) of cultured fecal bacteria was discovered in human gut targeted screening. This study provides important information to expand our current understanding of the structure/activity relationship of ADAS and putative inhibitors/activators that are potentially involved in ADAS appearance/disappearance. The NCBI database analysis revealed that ADAS presents at a large proportion in American Indian Oklahoman (C&A) with a high prevalence of obesity/diabetes and in colorectal cancer (CRC) patients from the US and China. An Oklahoman non-native group (NNI) showed no ADAS. Comparison of two large US populations reveals that ADAS is more frequent in individuals aged ≥66 and in females. Prevalence and levels of fecal metabolites are altered in the C&A and CRC groups versus controls. Biogenic amines (histamine, tryptamine, tyramine, phenylethylamine, cadaverine, putrescine, agmatine, spermidine) that present in food and are produced by gut microbiota are significantly higher in C&A (e.g., histamine/histidine 95-fold) versus NNI (histamine/histidine 16-fold). The majority of these bio-amines are cytotoxic at concentrations found in food. Inositol phosphate signaling implicated in AD is altered in C&A and CRC. Tryptamine stimulated accumulation of inositol phosphate. The seizure-eliciting tryptamine induced cytoplasmic vacuolization and vesiculation with cell fragmentation. Present additions of ADAS-carriers at different ages including infants led to an ADAS-comprising human sample size of 2,830 from 27 studies from four continents (North America, Australia, Asia, Europe). Levels of food-derived monoamine oxidase inhibitors and anti-bacterial compounds, the potential modulators of ADAS-bacteria growth and biogenic amine production, were altered in C&A versus NNI. ADAS is attributable to potentially modifiable risk factors of AD associated diseases.

Ursolic acid: A systematic review of its pharmacology, toxicity and rethink on its pharmacokinetics based on PK-PD model

Ursolic acid (UA) is a natural pentacyclic triterpenoid compound existing in various traditional Chinese medicinal herbs, and it possesses diverse pharmacological actions and some undesirable adverse effects, even toxicological activities. Due to UA's low solubility and poor bioavailability, and its interaction with gut microbiota after oral administration, the pharmacokinetics of UA remain elusive, leading to obscurity in the pharmacokinetics-pharmacodynamics (PK-PD) profile and relationship for UA. Based on literatures from PubMed, Google Scholar, ResearchGate, Web of Science and Wiley Online Library, with keywords of "pharmacology", "toxicology", "pharmacokinetics", "PK-PD" and "ursolic acid", herein we systematically review the pharmacology and toxicity of UA, and rethink on its pharmacokinetics on the basis of PK-PD model, and seek to delineate the underlying mechanisms for the characteristics of pharmacology and toxicology of UA, and for the pharmacokinetic features of UA particularly from the organ tropism and the interactions between UA and gut microbiota, and lay a solid foundation for development of UA-derived therapeutic agents in clinical settings.

Autophagy inhibition enhances the inhibitory effects of ursolic acid on lung cancer cells

The aim of the present study was to identify natural compounds that bear significant anti‑tumor activity. Thus, the effects of 63 small molecules that were isolated from traditional Chinese medicinal herbs on A549 human non‑small cell lung cancer (NSCLC) and MCF‑7 breast cancer cells were examined. It was found that ursolic acid (UA), a natural pentacyclic triterpenoid, exerted significant inhibitory effect on these cells. Further experiments revealed that UA inhibited the proliferation of various lung cancer cells, including the NSCLC cells, H460, H1975, A549, H1299 and H520, the human small cell lung cancer (SCLC) cells, H82 and H446, and murine Lewis lung carcinoma (LLC) cells. UA induced the apoptosis and autophagy of NSCLC cells. The inhibition of the mammalian target of rapamycin (mTOR) signaling pathway, but not the activation of the extracellular signal‑regulated kinase 1/2 (ERK1/2) signaling pathway contributed to the UA‑induced autophagy of NSCLC cells. Moreover, the inhibition of autophagy by chloroquine (CQ) or siRNA for autophagy‑related gene 5 (ATG5) enhanced the UA‑induced inhibition of cell proliferation and promotion of apoptosis, indicating that UA‑induced autophagy is a pro‑survival mechanism in NSCLC cells. On the whole, these findings suggest that combination treatment with autophagy inhibitors may be a novel strategy with which enhance the antitumor activity of UA in lung cancer.

Antimycobacterial activity of azepanobetulin and its derivative: In vitro, in vivo, ADMET and docking studies

The antimycobacterial investigation of azepanobetulin and its amide derivative was performed. Both compounds showed increased in vitro antibacterial activity on the H37Rv MTB strain in aerobic and anaerobic conditions. Basing on differences between MIC and IC₅₀ values a predominant bactericidal effect for amide in contrast to azepanobetulin with a bacteriostatic antibacterial mechanism is defined. Both compounds showed a strong antibacterial effect against resistant MTB strains with amide derivative being slightly more active. Amide derivative also showed a higher antibacterial potency against non-tuberculous mycobacterial strains (M. avium, M. abscessus). Molecular docking studies showed that the inhibition of tuberculosinyl adenosine transferase (Rv3378c) could constitute an antimycobacterial mechanism of action for these triterpenic azepane derivatives. The pharmacokinetic profile was evaluated by ADMET studies and azepanobetulin showing the better results was evaluated by in vivo experiments. This compound has demonstrated a statistically significant antimycobacterial activity compared to control, but inferior to isoniazid. Our findings show that pentacyclic triterpene derivatives holding a seven-membered azepane A-ring are the promising template for the development of new agents with high antibacterial potential against M. tuberculosis H37Rv, non-tuberculous mycobacterial and drug- resistant strains.

Oleanolic acid causes reversible contraception in male mice by increasing the permeability of the germinal epithelium

The effects of oleanolic acid (OA) on the fertility of male mice were investigated using both invivo and invitro experimental models. The experimental group (n=12) was treated with a daily dose of 30mgOAkg-1 bodyweight (i.p.), while the control group (n=6) received a daily dose of 10% ethanol solution (1mLkg-1 bodyweight). The effect of OA on the permeability status of TM4 Sertoli monolayers was investigated by measuring the transepithelial electrical resistance (TER), intracellular electrical resistance and semiquantitative RT-PCR. After 45 days, OA-treated males produced no pregnancies but in the control group, all 12 females were impregnated (69 offspring). Male mice, which demonstrated sterility when exposed to OA, recovered their fertility after 30 days (78 offspring). Testicular histological observations of OA-treated mice showed detachment of adjacent Sertoli-Sertoli cells. A control monolayer developed TER of 300-400 Ω.cm2, but OA (50, 100, 200µgL-1) treated monolayers developed TER of approximately 100Ω.cm2. Intracellular electrophysiological and RT-PCR data supported the premise that OA compromised tight junctional permeability. The study demonstrated reversible contraception in male mice by increasing the permeability of the germinal epithelium and further postulates that contraceptive reversibility is brought about by the reconstitution of the paracellular junctions between adjacent Sertoli cells.

Terpenoids as Potential Geroprotectors

Terpenes and terpenoids are the largest groups of plant secondary metabolites. However, unlike polyphenols, they are rarely associated with geroprotective properties. Here we evaluated the conformity of the biological effects of terpenoids with the criteria of geroprotectors, including primary criteria (lifespan-extending effects in model organisms, improvement of aging biomarkers, low toxicity, minimal adverse effects, improvement of the quality of life) and secondary criteria (evolutionarily conserved mechanisms of action, reproducibility of the effects on different models, prevention of age-associated diseases, increasing of stress-resistance). The number of substances that demonstrate the greatest compliance with both primary and secondary criteria of geroprotectors were found among different classes of terpenoids. Thus, terpenoids are an underestimated source of potential geroprotectors that can effectively influence the mechanisms of aging and age-related diseases.

In silico Molecular Docking Analysis Targeting SARS-CoV-2 Spike Protein and Selected Herbal Constituents

In modern drug discovery, molecular docking analysis is routinely used to understand and predict the interaction between a drug molecule and a target protein from a microbe. Drugs identified in this way may inhibit the entry and replication of pathogens in host cells. The SARS-CoV-2 associated coronavirus disease, COVID-19, has become the most contagious and deadly pandemic disease in the world today. In abeyance of any specific vaccine or therapeutic against SARS-CoV-2, the burgeoning situation urges a need for effective drugs to treat the virus-infected patients. Herbal medicines have been used as natural remedies for treating various infectious diseases since ancient times. The spike (S) protein of SARS-CoV-2 is important for the attachment and pathogenesis of the virus. Therefore, this study focused on the search of useful ligands for S protein among active constituents present in common herbs that could serve as efficient remedies for COVID-19. We analysed the binding efficiency of twelve compounds present in common herbs with the S protein of SARS-CoV-2 through molecular docking analysis and also results are validated with two different docking tools. The binding efficiency of ligands was scored based on their predicted pharmacological interactions coupled with binding energy estimates. In docking analysis, compound “I” (Epigallocatechin gallate (EGCG)) was found to have the highest binding affinity with the viral S protein, followed by compounds, “F” (Curcumin),“D” (Apigenin) and “E” (Chrysophanol). The present study corroborates that compound “I” (EGCG) mostly present in the integrants of green tea, shows the highest potentiality for acting as an inhibitor of SARS-CoV-2. Further, characterization of the amino acid residues comprising the viral binding site and the nature of the hydrogen bonding involved in the ligand-receptor interaction revealed significant findings with herbal compound “I” (EGCG) binding to the S protein at eight amino acid residues. The binding sites are situated near to the amino acids which are required for virus pathogenicity. The findings of the present study need in vivo experiments to prove the utility of “I”, “F”,“D” and “E” compounds and their further use in making herb-based anti-SARS-CoV-2 product in near future. This analysis may help to create a new ethno-drug formulation for preventing or curing the COVID-19.

Modifications of the Protein Characteristics of Pacaya Caused by Thermal Treatment: A Spectroscopic, Electrophoretic and Morphological Study

The inflorescences of Chamaedorea tepejilote Liebm. are consumed as food in Central America and southern Mexico but is an underutilized food because of its sensory characteristics, principally due to its bitter taste. However, the inflorescences of Chamaedorea tepejilote Liebm. are nutritionally promising due to their high protein content (approximately 25%). Protein isolates from pacaya were modified via three different thermal treatments to determine the effect of the treatments on the protein structures. Scanning electron microscopy indicated that the pacaya protein isolate particles had less rough and irregular surfaces with larger particle sizes due to an aggregation process when a thermal treatment was used compared to those when no thermal treatment was used. An increase in the intensity of the low molecular weight protein fractions (≤20 kDa) in the electrophoretic pattern of the proteins was observed, which was generated by the hydrolysis of the proteins by heat treatment. The modifications in the FT-IR spectra showed that thermal treatment of pacaya affected the secondary structure of its proteins, mainly when microwave treatment was used. Raman spectroscopy revealed that the α-helical structure was dominant in the proteins of pacaya and that thermal treatment increased the fraction of the β-sheet structure at the expense of the α-helical structure.

Immunomodulatory effects and structure-activity relationship of botanical pentacyclic triterpenes: A review

Botanical pentacyclic triterpenes possessed a broad range of pharmacological activities such as anti-oxidant, anti-tumor, anti-microbial and anti-inflammatory activities. It is believed that the mechanisms involved in these bioactivities are due to the modulation of immune system. Recently, the pharmacological validation on immunomodulatory of pentacyclic triterpenes derived from higher plants is very limited and several existence review papers related for this group of compound have not been focused for this activity. In this review, we have highlighted several studies on immunomodulatory potential of botanical pentacyclic triterpenes isolated from wide array of different species of medicinal plants and herbs based on various preclinical in vitro and animal models. This review also attempts to discuss on bioactivities of compouns related with their structure-activity relationship. Hence, the evaluation of pentacyclic triterpenes offers a great opportunity to discover adjuvants and novel therapeutic agents that presented beneficial immunomodulatory properties.

Plant triterpenoid saponins: biosynthesis, in vitro production, and pharmacological relevance

The saponins are a diverse class of natural products, with a broad scale distribution across different plant species. Chemically characterized as triterpenoid glycosides, they posses a 30C oxidosqualene precursor-based aglycone moiety (sapogenin), to which glycosyl residues are subsequently attached to yield the corresponding saponin. Based on the chemically distinct aglycone moieties, broadly, they are divided into triterpenoid saponins (dammaranes, ursanes, oleananes, lupanes, hopanes, etc.) and the sterol glycosides. This review aims to present in detail the biosynthesis patterns of the different aglycones from a common precursor and their glycosylation patterns to yield the functionally active glycoside. The review also presents recent advances in the pharmacological activities of these saponins, particularly as potent anti-neoplastic pharmacophores, antioxidants, or anti-viral/antibacterial agents. Since alternate production pedestals for these pharmacologically important triterpenes via cell and tissue cultures are an attractive option for their sustainable production, recent trends in the variety and scale of in vitro production of plant triterpenoids have also been discussed.

The potential of plant systems to break the HIV-TB link

Tuberculosis (TB) and human immunodeficiency virus (HIV) can place a major burden on healthcare systems and constitute the main challenges of diagnostic and therapeutic programmes. Infection with HIV is the most common cause of Mycobacterium tuberculosis (Mtb), which can accelerate the risk of latent TB reactivation by 20-fold. Similarly, TB is considered the most relevant factor predisposing individuals to HIV infection. Thus, both pathogens can augment one another in a synergetic manner, accelerating the failure of immunological functions and resulting in subsequent death in the absence of treatment. Synergistic approaches involving the treatment of HIV as a tool to combat TB and vice versa are thus required in regions with a high burden of HIV and TB infection. In this context, plant systems are considered a promising approach for combatting HIV and TB in a resource-limited setting because plant-made drugs can be produced efficiently and inexpensively in developing countries and could be shared by the available agricultural infrastructure without the expensive requirement needed for cold chain storage and transportation. Moreover, the use of natural products from medicinal plants can eliminate the concerns associated with antiretroviral therapy (ART) and anti-TB therapy (ATT), including drug interactions, drug-related toxicity and multidrug resistance. In this review, we highlight the potential of plant system as a promising approach for the production of relevant pharmaceuticals for HIV and TB treatment. However, in the cases of HIV and TB, none of the plant-made pharmaceuticals have been approved for clinical use. Limitations in reaching these goals are discussed.

Supplementation of Plants with Immunomodulatory Properties during Pregnancy and Lactation-Maternal and Offspring Health Effects

A pregnant woman’s diet consists of many products, such as fruits, vegetables, cocoa, tea, chocolate, coffee, herbal and fruit teas, and various commercially available dietary supplements, which contain a high number of biological active plant-derived compounds. Generally, these compounds play beneficial roles in women’s health and the development of fetus health. There are, however, some authors who report that consuming excessive amounts of plants that contain high concentrations of polyphenols may negatively affect the development of the fetus and the offspring’s health. Important and problematic issues during pregnancy and lactation are bacterial infections treatment. In the treatment are proposals to use plant immunomodulators, which are generally considered safe for women and their offspring. Additional consumption of biologically active compounds from plants, however, may increase the risk of occurrences to irreversible changes in the offspring’s health. Therefore, it is necessary to carry out safety tests for immunomodulators before introducing them into a maternal diet. Here, we present data from animal experiments for the four most-studied plants immunomodulators genus: Rhodiola, Echinacea, Panax, and Camellia, which were used in maternal nutrition.

Ursolic Acid and Its Derivatives as Bioactive Agents

Non-communicable diseases (NCDs) such as cancer, diabetes, and chronic respiratory and cardiovascular diseases continue to be threatening and deadly to human kind. Resistance to and side effects of known drugs for treatment further increase the threat, while at the same time leaving scientists to search for alternative sources from nature, especially from plants. Pentacyclic triterpenoids (PT) from medicinal plants have been identified as one class of secondary metabolites that could play a critical role in the treatment and management of several NCDs. One of such PT is ursolic acid (UA, 3 β-hydroxy-urs-12-en-28-oic acid), which possesses important biological effects, including anti-inflammatory, anticancer, antidiabetic, antioxidant and antibacterial effects, but its bioavailability and solubility limits its clinical application. Mimusops caffra, Ilex paraguarieni, and Glechoma hederacea, have been reported as major sources of UA. The chemistry of UA has been studied extensively based on the literature, with modifications mostly having been made at positions C-3 (hydroxyl), C12-C13 (double bonds) and C-28 (carboxylic acid), leading to several UA derivatives (esters, amides, oxadiazole quinolone, etc.) with enhanced potency, bioavailability and water solubility. This article comprehensively reviews the information that has become available over the last decade with respect to the sources, chemistry, biological potency and clinical trials of UA and its derivatives as potential therapeutic agents, with a focus on addressing NCDs.

Terpene Derivatives as a Potential Agent against Antimicrobial Resistance (AMR) Pathogens

The evolution of antimicrobial resistance (AMR) in pathogens has prompted extensive research to find alternative therapeutics. Plants rich with natural secondary metabolites are one of the go-to reservoirs for discovery of potential resources to alleviate this problem. Terpenes and their derivatives comprising of hydrocarbons, are usually found in essential oils (EOs). They have been reported to have potent antimicrobial activity, exhibiting bacteriostatic and bactericidal effects against tested pathogens. This brief review discusses the activity of terpenes and derivatives against pathogenic bacteria, describing the potential of the activity against AMR followed by the possible mechanism exerted by each terpene class. Finally, ongoing research and possible improvisation to the usage of terpenes and terpenoids in therapeutic practice against AMR are discussed.

Lupeol induces immunity and protective efficacy in a murine model against visceral leishmaniasis

The available chemotherapeutics for the cure of visceral leishmaniasis (VL) are linked with many detrimental effects. Moreover, VL is associated with the suppression of protective Th1 immune response of the host and induction of disease exaggerating Th2 immune response. Therefore, there is an urgent requirement of therapeutics which can augment the immune status of the host to cure this disease. In the current investigation, the antileishmanial potential of lupeol was monitored in vitro and in vivo in inbred BALB/c mice against Leishmania donovani. Lupeol showed potent antipromastigote activity via arresting parasites at sub G0/G1 phase in vitro. Lupeol significantly decreased the splenic parasite burden by inducing strong delayed-type hypersensitivity responses in contrary to untreated infected animals. The therapeutic efficacy of lupeol was observed to be similar to the reference drug, AmB. Treatment of infected animals with lupeol depicted enhanced levels of T cells and Th1 cytokines in contrast to only infected controls. Further lupeol treatment upregulated the levels of nuclear factor κ B and nitric oxide synthase genes and elevated the production of reactive oxygen species and nitric oxide. Unlike AmB, lupeol-treated infected animals did not show any toxicity. These findings are promising and indicate that lupeol can serve as a prototype drug for the cure of VL.

The Mechanism of Action of Ursolic Acid as a Potential Anti-Toxoplasmosis Agent, and Its Immunomodulatory Effects

This study was performed to investigate the mechanism of action of ursolic acid in terms of anti-Toxoplasma gondii effects, including immunomodulatory effects. We evaluated the anti-T. gondii effects of ursolic acid, and analyzed the production of nitric oxide (NO), reactive oxygen species (ROS), and cytokines through co-cultured immune cells, as well as the expression of intracellular organelles of T. gondii. The subcellular organelles and granules of T. gondii, particularly rhoptry protein 18, microneme protein 8, and inner membrane complex sub-compartment protein 3, were markedly decreased when T. gondii was treated with ursolic acid, and their expressions were effectively inhibited. Furthermore, ursolic acid effectively increased the production of NO, ROS, interleukin (IL)-10, IL-12, granulocyte macrophage colony stimulating factor (GM-CSF), and interferon-β, while reducing the expression of IL-1β, IL-6, tumor necrosis factor alpha (TNF-α), and transforming growth factor beta 1 (TGF-β1) in T. gondii-infected immune cells. These results demonstrate that ursolic acid not only causes anti-T. gondii activity/action by effectively inhibiting the survival of T. gondii and the subcellular organelles of T. gondii, but also induces specific immunomodulatory effects in T. gondii-infected immune cells. Therefore, this study indicates that ursolic acid can be effectively utilized as a potential candidate agent for developing novel anti-toxoplasmosis drugs, and has immunomodulatory activity.

Preparative separation of structural isomeric pentacyclic triterpene oleanolic acid and ursolic acid from natural products by pH-zone-refining countercurrent chromatography

In this work, pH-zone-refining countercurrent chromatography was investigated in the preparative separation of two bioactive components, oleanolic acid and ursolic acid, from three different natural products, Aralia chinensis, apple peels and Eriobotrya japonica Thunb. Oleanolic acid and ursolic acid are structurally isomeric pentacyclic triterpene acids that are widely distributed in many natural products. However, it was difficult to separate these components with high purity by conventional methods. A biphasic solvent system composed of n-hexane–dichloromethane–methanol–water (7 : 3 : 2 : 8, v/v) was selected, in which an optimized concentration of 10 mmol L⁻¹ trifluoroacetic acid was added in the upper phase as the retainer and 10 mmol L⁻¹ ammonia (with 25–28% NH₃) was added in the aqueous phase as the eluter. Consequently, 38.56 mg of oleanolic acid with 99.01% purity was separated from 100 mg of the crude extract of Aralia chinensis, while 65.6 mg of a mixture of ursolic acid (90.98%) and oleanolic acid (6.51%) and 46.6 mg of a mixture of ursolic acid (74.35%) and oleanolic acid (23.61%) were separated from 100 mg of the crude extract of apple peels and 100 mg of the crude extract of Eriobotrya japonica Thunb., respectively, by pH-zone-refining countercurrent chromatography using the above selected biphasic solvent system. The results showed that pH-zone-refining countercurrent chromatography is an efficient method for the preparative separation of pentacyclic triterpene acids from natural products.

pH-zone-refining countercurrent chromatography was investigated in preparative separation of oleanolic acid and ursolic acid from three different natural products, Aralia chinensis, apple peels and Eriobotrya japonica Thunb.

Ursolic acid and carvacrol may be potential inhibitors of dormancy protein small heat shock protein16.3 of Mycobacterium tuberculosis

Small heat shock protein16.3 (sHSP16.3) is a crucial protein for survival of Mycobacterium tuberculosis (MTB) in its host. Besides, this protein acts as a molecular chaperone during stress and is indispensable for MTB's growth, virulence and cell-wall thickening. sHSP16.3 is also a promising candidate for vaccine, serodiagnosis and drug design as well. In the present study, we have targeted sHSP16.3 with two phytochemicals, namely ursolic acid and carvacrol using in silico approach. Molecular docking analysis showed that both phytochemicals (ursolic acid and carvacrol) have docked with sHSP16.3 and shown tendency to inhibit the function of this vital protein of MTB. In addition, both compounds have exhibited strong compatibility with sHSP16.3 during whole 60 ns duration of molecular dynamics simulation. Further, the molecular mechanic/generalized Born/Poisson-Boltzmann surface area (MM/G/P/BSA) free energies were calculated which showed that both phytocompounds have stable and favourable binding energies causing strong binding with binding site of sHSP16.3. Taking together, the data of present study suggest that both phytocompounds may be potential inhibitor of sHSP16.3 of MTB and a best alternative to standard anti-tuberculosis drugs.