Isolation of anti-mycobacterial compounds from Curtisia dentata (Burm.f.) C.A.Sm (Curtisiaceae)

Systemic Pharmacology Reveals the Potential Targets and Signaling Mechanisms in the Adjuvant Treatment of Brucellosis with Traditional Chinese Medicine

Human brucellosis is one of the world's most common zoonoses, caused by Brucella infection and characterized by induced inflammation, which in severe cases can lead to abortion and sterility in humans and animals. There is growing evidence that traditional Chinese medicine (TCM) is beneficial as an adjunct to the treatment of brucellosis. However, its specific targets of action and molecular mechanisms remain unclear. In this study, a systematic pharmacological approach was applied to demonstrate pharmacological targets, biological functions, and signaling pathways of TCM as an adjunct to the treatment of brucellosis (TCMTB). The results of network pharmacology were further verified by in vitro experiments. Network analysis revealed that 133 active ingredients and 247 targets were screened in TCMTB. Further data analysis identified 21 core targets and 5 core compounds in TCMTB, including beta-sitosterol, quercetin, kaempferol, luteolin, and paeoniflorin. Gene ontology and the Kyoto Encyclopedia of Gene and Genome analysis showed that TCMTB might actively treat brucellosis by regulating inflammatory response, enhancing immune function, and targeting signaling pathways such as tuberculosis and TNF. Molecular docking results showed that multiple compounds could bind to multiple targets. Further, in vitro experiments confirmed that quercetin, among the active compounds screened, induced the strongest immunomodulatory and pro-inflammatory cytokine production during Brucella abortus infection. Further, quercetin induced nitric oxide production, which attenuated the ability of B. abortus to internalize THP-1 cells as well as intracellular survival. This study reveals the mechanism by which TCMTB aids in the treatment of brucellosis through a synergistic multicomponent, multipathway, and multitarget action. The contribution of quercetin treatment to B. abortus infection was demonstrated for the first time, which may be related to the quercetin-induced production of nitric oxide and immunomodulatory and inflammatory cytokines. These predictions of the core compounds and targets may be used in the future for the clinical treatment of brucellosis.

An Inventory of South African Medicinal Plants Used in the Management of Sexually Transmitted and Related Opportunistic Infections: An Appraisal and Some Scientific Evidence (1990-2020)

The current work is aimed at generating the first inventory of South African medicinal plants used in the treatment of sexually transmitted and related opportunistic infections associated with HIV-AIDS. This is important in assisting researchers to access a list of plant species to evaluate for potential phytocompounds, as this area of research is greatly lagging in South Africa. A total of 335 medicinal plants from 103 families have been documented in the current work. The most represented families are Fabaceae (11.64%) and Asteraceae (6.27%). Herbs constitute 36.53%, trees 32.34%, shrubs 29.04%, climbers 1.80% and parasites 0.30%. It is worrying that on the plant parts used, the roots constitute 47.18%, while leaves and stem bark yield 16.62 and 15.01%, respectively. Catharanthus roseus exhibited the highest number of citations (19), while Peltophorum africanum had 14 and both Carica papaya and Vachelia karoo had 12. In the mode of administration of the reported medicinal plant species, most of the plants are boiled and taken orally (48.22%), while other plant species are used as mouth washes (3.25%). Although there is reasonable in vitro activity of some of the plant species, validating the relevance of use, there is still a need to explore the mode of action of such plant species; isolated compounds and possible derivatives thereof are of paramount importance and need to be explored as well. Furthermore, toxicological aspects of such plant species need to be explored.

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.

Ursolic acid as a potential inhibitor of Mycobacterium tuberculosis cytochrome bc1 oxidase-a molecular modelling perspective

The escalating burden of tuberculosis disease and drastic effects of current medicine has stimulated a search for alternative drugs. A medicinal plant Warburgia salutaris has been reported to possess inhibitory properties against M. tuberculosis. In this study, we apply computational methods to investigate the probability of W. salutaris compounds as potential inhibitors of M. tuberculosis QcrB protein. We performed molecular docking, molecular dynamics simulations, radius of gyration, principal component analysis (PCA), and molecular mechanics-generalized born surface area (MM-GBSA) binding-free energy calculations in explicit solvent to achieve our objective. The results suggested that ursolic acid (UA) and ursolic acid acetate (UAA) could serve as preferred potential inhibitors of mycobacterial QcrB compared to lansoprazole sulphide (LSPZ) and telacebec (Q203)-UA and UAA have a higher binding affinity to QcrB compared to LSPZ and Q203 drugs. UA binding affinity is attributed to hydrogen bond formation with Val120, Arg364 and Arg366, and largely resonated from van der Waals forces resulting from UA interactions with hydrophobic amino acids in its vicinity. UAA binds to the porphyrin ring binding site with higher binding affinity compared to LSPZ. The binding affinity results primarily from van der Waals forces between UAA and hydrophobic residues of QcrB in the porphyrin ring binding site where UAA binds competitively. UA and UAA formed stable complexes with the protein with reduced overall residue mobility, consequently supporting the magnitude of binding affinity of the respective ligands. UAA could potentially compete with the porphyrin ring for the binding site and deprive the mycobacterial cell from oxygen, consequently disturbing mycobacterial oxygen-dependent metabolic processes. Therefore, discovery of a compound that competes with porphyrin ring for the binding site may be useful in QcrB pharmocological studies. UA proved to be a superior compound, although its estimated toxicity profile revealed UA to be hepatotoxic within acceptable parameters. Although preliminary findings of this report still warrant experimental validation, they could serve as a baseline for the development of new anti-tubercular drugs from natural resources that target QcrB.

Potential Anti-Mycobacterium tuberculosis Activity of Plant Secondary Metabolites: Insight with Molecular Docking Interactions

Tuberculosis (TB) is a recurrent and progressive disease, with high mortality rates worldwide. The drug-resistance phenomenon of Mycobacterium tuberculosis is a major obstruction of allelopathy treatment. An adverse side effect of allelopathic treatment is that it causes serious health complications. The search for suitable alternatives of conventional regimens is needed, i.e., by considering medicinal plant secondary metabolites to explore anti-TB drugs, targeting the action site of M. tuberculosis. Nowadays, plant-derived secondary metabolites are widely known for their beneficial uses, i.e., as antioxidants, antimicrobial agents, and in the treatment of a wide range of chronic human diseases (e.g., tuberculosis), and are known to “thwart” disease virulence. In this regard, in silico studies can reveal the inhibitory potential of plant-derived secondary metabolites against Mycobacterium at the very early stage of infection. Computational approaches based on different algorithms could play a significant role in screening plant metabolites against disease virulence of tuberculosis for drug designing.

New Investigations with Lupane Type A-Ring Azepane Triterpenoids for Antimycobacterial Drug Candidate Design

Twenty lupane type A-ring azepano-triterpenoids were synthesized from betulin and its related derivatives and their antitubercular activity against Mycobacterium tuberculosis, mono-resistant MTB strains, and nontuberculous strains Mycobacterium abscessus and Mycobacterium avium were investigated in the framework of AToMIc (Anti-mycobacterial Target or Mechanism Identification Contract) realized by the Division of Microbiology and Infectious Diseases, NIAID, National Institute of Health. Of all the tested triterpenoids, 17 compounds showed antitubercular activity and 6 compounds were highly active on the H37Rv wild strain (with MIC 0.5 µM for compound 7), out of which 4 derivatives also emerged as highly active compounds on the three mono-resistant MTB strains. Molecular docking corroborated with a machine learning drug-drug similarity algorithm revealed that azepano-triterpenoids have a rifampicin-like antitubercular activity, with compound 7 scoring the highest as a potential M. tuberculosis RNAP potential inhibitor. FIC testing demonstrated an additive effect of compound 7 when combined with rifampin, isoniazid and ethambutol. Most compounds were highly active against M. avium with compound 14 recording the same MIC value as the control rifampicin (0.0625 µM). The antitubercular ex vivo effectiveness of the tested compounds on THP-1 infected macrophages is correlated with their increased cell permeability. The tested triterpenoids also exhibit low cytotoxicity and do not induce antibacterial resistance in MTB strains.

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.

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.

Caspicaiene: a new kaurene diterpene with anti-tubercular activity from an Aspergillus endophytic isolate in Gleditsia caspia desf

A new kaurene derivative with a new 6/6/6/5/6 ring system structure, given the trivial name caspicaiene, was isolated from the fungal culture of the Aspergillus N830 isolate identified by ITS region DNA sequencing. The compound was characterized by 1, 2 D NMR, and HR-ESI-MS-MS and revealed a promising anti-tubercular effect using the Alamar Blue Assay (MABA), in a dose dependent manner, with MIC value of 124.5 µM. Furthermore, six known compounds were isolated and showed significant MIC values against Mycobacterium tuberculosis, ranging between 15.63 µg/mL (26.5 µM) to 125 µg/mL (500 µM), compared to the positive control isoniazid whose MIC value was 0.24 µg/mL (1.75 µM), which sets them forth as potentially natural anti-tubercular agents. To gain further insight of the underlying mechanism, in-silico molecular docking, using the C-Docker protocol, was conducted and demonstrated various interactions between the isolated compounds and three key mycobacterial enzymes. Additionally, the cytotoxic activity was reported and showed the safety of these molecules according to the calculated safety index in the human hepatic cancer cell line (HepG2) and Vero cell lines.

A review of medicinal plant of Middle East and North Africa (MENA) region as source in tuberculosis drug discovery

Tuberculosis (TB) is a disease that affects one-third of the world's population. Although currently available TB drugs have many side effects, such as nausea, headache and gastrointestinal discomfort, no new anti-TB drugs have been produced in the past 30 years. Therefore, the discovery of a new anti-TB agent with minimal or no side effects is urgently needed. Many previous works have reported the effects of medicinal plants against Mycobacterium tuberculosis (MTB). However, none have focused on medicinal plants from the Middle Eastern and North African (MENA) region. This review highlights the effects of medicinal plants from the MENA region on TB. Medicinal plants from the MENA region have been successfully used as traditional medicine and first aid against TB related problems. A total of 184 plants species representing 73 families were studied. Amongst these species, 93 species contained more active compounds with strong anti-MTB activity (crude extracts and/or bioactive compounds with activities of 0-100 µg/ml). The extract of Inula helenium, Khaya senegalensis, Premna odorata and Rosmarinus officinalis presented the strongest anti-MTB activity. In addition, Boswellia papyrifera (Del) Hochst olibanum, Eucalyptus camaldulensis Dehnh leaves (river red gum), Nigella sativa (black cumin) seeds and genus Cymbopogon exhibited anti-TB activity. The most potent bioactive compounds included alantolactone, octyl acetate, 1,8-cineole, thymoquinone, piperitone, α- verbenol, citral b and α-pinene. These compounds affect the permeability of microbial plasma membranes, thus kill the mycobacterium spp. As a conclusion, plant species collected from the MENA region are potential sources of novel drugs against TB.

Isoniazid-phytochemical conjugation: A new approach for potent and less toxic anti-TB drug development

Mycobacterium tuberculosis (Mtb) causes one of the most grievous pandemic infectious diseases, tuberculosis (TB), with long-term morbidity and high mortality. The emergence of drug-resistant Mtb strains, and the co-infection with human immunodeficiency virus, challenges the current WHO-TB stewardship programs. The first-line anti-TB drugs, isoniazid (INH) and rifampicin (RIF), have become extensively obsolete in TB control from chromosomal mutations during the last decades. However, based on clinical trial statistics, the production of well-tolerated anti-TB drug(s) is miserably low. Alternately, semi-synthesis or structural modifications of first-line obsolete antitubercular drugs remain as the versatile approach for getting some potential medicines. The use of any suitable phytochemicals with INH in a hybrid formulation could be an ideal approach for the development of potent anti-TB drug(s). The primary objective of this review was to highlight and analyze available INH-phytochemical hybrid research works. The utilization of phytochemicals through chemical conjugation is a new trend toward the development of safer/non-toxic anti-TB drugs.

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.

Betulinic acid, derived from the desert lavender Hyptis emoryi, attenuates paclitaxel-, HIV-, and nerve injury-associated peripheral sensory neuropathy via block of N- and T-type calcium channels

The Federal Pain Research Strategy recommended development of nonopioid analgesics as a top priority in its strategic plan to address the significant public health crisis and individual burden of chronic pain faced by >100 million Americans. Motivated by this challenge, a natural product extracts library was screened and identified a plant extract that targets activity of voltage-gated calcium channels. This profile is of interest as a potential treatment for neuropathic pain. The active extract derived from the desert lavender plant native to southwestern United States, when subjected to bioassay-guided fractionation, afforded 3 compounds identified as pentacyclic triterpenoids, betulinic acid (BA), oleanolic acid, and ursolic acid. Betulinic acid inhibited depolarization-evoked calcium influx in dorsal root ganglion (DRG) neurons predominantly through targeting low-voltage-gated (Cav3 or T-type) and CaV2.2 (N-type) calcium channels. Voltage-clamp electrophysiology experiments revealed a reduction of Ca, but not Na, currents in sensory neurons after BA exposure. Betulinic acid inhibited spontaneous excitatory postsynaptic currents and depolarization-evoked release of calcitonin gene-related peptide from lumbar spinal cord slices. Notably, BA did not engage human mu, delta, or kappa opioid receptors. Intrathecal administration of BA reversed mechanical allodynia in rat models of chemotherapy-induced peripheral neuropathy and HIV-associated peripheral sensory neuropathy as well as a mouse model of partial sciatic nerve ligation without effects on locomotion. The broad-spectrum biological and medicinal properties reported, including anti-HIV and anticancer activities of BA and its derivatives, position this plant-derived small molecule natural product as a potential nonopioid therapy for management of chronic pain.

Antimycobacterial, Enzyme Inhibition, and Molecular Interaction Studies of Psoromic Acid in Mycobacterium tuberculosis: Efficacy and Safety Investigations

The current study explores the antimycobacterial efficacy of lichen-derived psoromic acid (PA) against clinical strains of Mycobacterium tuberculosis (M.tb). Additionally, the inhibitory efficacy of PA against two critical enzymes associated with M.tb, namely, UDP-galactopyranose mutase (UGM) and arylamine-N-acetyltransferase (TBNAT), as drug targets for antituberculosis therapy were determined. PA showed a profound inhibitory effect towards all the M.tb strains tested, with minimum inhibitory concentrations (MICs) ranging between 3.2 and 4.1 µM, and selectivity indices (SIs) ranging between 18.3 and 23.4. On the other hand, the standard drug isoniazid (INH) displayed comparably high MIC values (varying from 5.4 to 5.8 µM) as well as low SI values (13.0–13.9). Interestingly, PA did not exhibit any cytotoxic effects on a human liver hepatocellular carcinoma cell line even at the highest concentration tested (75 µM). PA demonstrated remarkable suppressing propensity against UGM compared to standard uridine-5'-diphosphate (UDP), with 85.8 and 99.3% of inhibition, respectively. In addition, PA also exerted phenomenal inhibitory efficacy (half maximal inhibitory concentration (IC₅₀) value = 8.7 µM, and 77.4% inhibition) against TBNAT compared with standard INH (IC₅₀ value = 6.2 µM and 96.3% inhibition). Furthermore, in silico analysis validated the outcomes of in vitro assays, as the molecular interactions of PA with the active sites of UGM and TBNAT were unveiled using molecular docking and structure–activity relationship studies. Concomitantly, our findings present PA as an effective and safe natural drug plausible for use in controlling tuberculosis infections.

Evaluation of antimycobacterial activity of Curcuma xanthorrhiza ethanolic extract against Mycobacterium tuberculosis H37Rv in vitro

Aim:

The aim of this study was to evaluate the antimycobacterial activity of the Curcuma xanthorrhiza ethanolic extract in vitro.

Materials and Methods:

Ethanolic extract of C. xanthorrhiza was set by maceration method. The broth microdilution and disc diffusion method were used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC), respectively, of C. xanthorrhiza ethanol extract on strain Mycobacterium tuberculosis H37Rv.

Results:

C. xanthorrhiza ethanol extract was found to have the antimycobacterial effects with a MIC value of 1600 μg/ml while MBC value of 3200 μg/ml for M. tuberculosis H37Rv.

Conclusion:

From these findings , it can be concluded that C. xanthorrhiza ethanol extract have an antibacterial activity against Mycobacterium tuberculosis H37Rv in vitro and its potency elevated by increasing the C. xanthorrhiza ethanol extract concentration.