Southeast Asian Medicinal Plants as a Potential Source of Antituberculosis Agent

Phytochemical analysis of leaf extract of Piper nigrum and investigation of its biological activities

BACKGROUND

This study investigates the phytoconstituents of the less explored leaf of Piper nigrum, a common ethnomedicinal plant as an alternate source for multiple bioactivities.

METHODS

Hydro-ethanolic (1:4) extract of Piper nigrum leaves (PNLE) prepared and profiled using liquid chromatography and mass spectrometry for identification of phytomolecules. Anti-oxidant activity, intracellular reactive oxygen species (ROS) expression, phagocytosis activity, and cytokine expression were estimated using cell-free and cell-based assays. Anti-cancer activity was determined with cancer cell viability, migration inhibition and colony-formation assay. Apoptosis and membrane depolarization assay were done using fluorescent microscopic staining methods while network pharmacology, and molecular docking analysis were done using open source and online tools.

RESULTS

Major phytomolecules identified in PNLE were pentanamide N,N-didecyl, piperettine, curcumin, myristicin, pipernonaline, sesamin, and lupenone. PNLE exhibited anti-bacterial activity with higher activity against Gram-positive bacteria, Staphylococcus aureus. PNLE also showed anti-oxidant and anti-inflammatory activity through neutralization of free radicals; inhibition of intracellular ROS generation; inhibition of phagocytosis and reduction of cytokine (IL-6 and TNF-α) levels. PNLE showed anti-proliferative activity against human breast cancer cells (MDA-MB-231), rat mammary tumor cells (LA7), and mouse melanoma cells (B16-F10) with highest activity against MDA-MB-231 cells. The extract did not inhibit human kidney cells (HEK-293). Further, PNLE treatment significantly inhibited cell migration and colony formation of MDA-MB-231 cells. Fluorescent staining techniques confirmed induction of apoptosis in cancer cells by PNLE. Further, network pharmacology and molecular docking studies revealed that the identified PNLE phytomolecules share 97 targets of out of potential breast cancer and inflammation-related target genes with four best common target proteins among the top hub genes and sesamin showed the highest binding affinity with these important cellular targets.

CONCLUSIONS

Overall, the phytochemical profile of PNLE showed clear presence of important phytomolecules and their association with critical human cellular mechanistic pathways responsible for exhibited bioactivities. This study further establishes the leaf of P. nigrum as an additional anatomical plant part with potent medicinal properties and  as a potential renewable source for bioactive phyomolecules.

Antituberculosis, antioxidant and cytotoxicity profiles of quercetin: a systematic and cost-effective in silico and in vitro approach

The ineffectiveness and the slowdown of newer anti-TB drug approval rates directly indicate searching for potential alternative agents. However, validation of isolated phytochemicals through hit-and-trial experiments is more expensive and time-consuming. Simultaneously, cost-effective computational tools can recognize most potential candidates at an initial stage. The present study selected seven plant-derived polyphenols, then verified anti-TB and drug-ability profiles using advanced computational tools before the experimental study. Among all, the quercetin showed a potential docking-score within -8 to -11 kcal/mol than the standard isoniazid and ofloxacin, -5 to -10 kcal/mol. Additionally, quercetin exhibited a higher drug-ability score of 0.53 than isoniazid 0.19. Further, quercetin exhibited the minimum inhibitory concentration at 6 and 8 μg/mL, while ofloxacin showed at 2 μg/mL against InhA, and katG mutated Mtb-strains, respectively. Parallelly, quercetin showed promising free-radical-scavenging activity from nitric-oxide assay at IC₅₀ = 14.92 µg/mL, and lesser-cytotoxicity from cultured HepG2 cell lines at IC₅₀ = 159 µg/mL, respectively.

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.

Rhipicephalus Tick: A Contextual Review for Southeast Asia

Rhipicephalus species are distributed globally with a notifiable presence in Southeast Asia (SEA) within animal and human populations. The Rhipicephalus species are highly adaptive and have established successful coexistence within human dwellings and are known to be active all year round, predominantly in tropical and subtropical climates existing in SEA. In this review, the morphological characteristics, epidemiology, and epizootiology of Rhipicephalus tick species found in SEA are reviewed. There are six commonly reported Rhipicephalus ticks in the SEA region. Their interactions with their host species that range from cattle, sheep, and goats, through cats and dogs, to rodents and man are discussed in this article. Rhipicephalus-borne pathogens, including Anaplasma species, Ehrlichia species, Babesia species, and Theileria species, have been highlighted as are relevant to the region in review. Pathogens transmitted from Rhipicepahalus ticks to host animals are usually presented clinically with signs of anemia, jaundice, and other signs of hemolytic changes. Rhipicephalus ticks infestation also account for ectoparasitic nuisance in man and animals. These issues are discussed with specific interest to the SEA countries highlighting peculiarities of the region in the epidemiology of Rhipicephalus species and attendant pathogens therein. This paper also discusses the current general control strategies for ticks in SEA proffering measures required for increased documentation. The potential risks associated with rampant and improper acaricide use are highlighted. Furthermore, such practices lead to acaricide resistance among Rhipicephalus species are highlighted.

Potent anti-mycobacterial and immunomodulatory activity of some bioactive molecules of Indian ethnomedicinal plants that have the potential to enter in TB management

Tuberculosis (TB) is one of the deadliest infectious diseases of human civilization. Approximately one-third of global population is latently infected with the TB pathogen Mycobacterium tuberculosis (M.tb). The discovery of anti-TB antibiotics leads to decline in death rate of TB. However, the evolution of antibiotic-resistant M.tb-strain and the resurgence of different immune-compromised diseases re-escalated the death rate of TB. WHO has already cautioned about the chances of pandemic situation in TB endemic countries until the discovery of new anti-tubercular drugs, that is, the need of the hour. Analysing the pathogenesis of TB, it was found that M.tb evades the host by altering the balance of immune response and affects either by killing the cells or by creating inflammation. In the pre-antibiotic era, traditional medicines were only therapeutic measures for different infectious diseases including tuberculosis. The ancient literatures of India or ample Indian traditional knowledge and ethnomedicinal practices are evidence for the treatment of TB using different indigenous plants. However, in the light of modern scientific approach, anti-TB effects of those plants and their bioactive molecules were not established thoroughly. In this review, focus has been given on five bioactive molecules of different traditionally used Indian ethnomedicinal plants for treatment of TB or TB-like symptom. These compounds are also validated with proper identification and their mode of action with modern scientific approaches. The effectiveness of these molecules for sensitive or drug-resistant TB pathogen in clinical or preclinical studies was also evaluated. Thus, our specific aim is to highlight such scientifically validated bioactive compounds having anti-mycobacterial and immunomodulatory activity for future use as medicine or adjunct-therapeutic molecule for TB management.

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.

Phenolic Compounds as Promising Drug Candidates in Tuberculosis Therapy

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB) remains one of the deadliest, infectious diseases worldwide. The detrimental effects caused by the existing anti-TB drugs to TB patients and the emergence of resistance strains of M. tuberculosis has driven efforts from natural products researchers around the globe in discovering novel anti-TB drugs that are more efficacious and with less side effects. There were eleven main review publications that focused on natural products with anti-TB potentials. However, none of them specifically emphasized antimycobacterial phenolic compounds. Thus, the current review’s main objective is to highlight and summarize phenolic compounds found active against mycobacteria from 2000 to 2017. Based on the past studies in the electronic databases, the present review also focuses on several test organisms used in TB researches and their different distinct properties, a few types of in vitro TB bioassay and comparison between their strengths and drawbacks, different methods of extraction, fractionation and isolation, ways of characterizing and identifying isolated compounds and the mechanism of actions of anti-TB phenolic compounds as reported in the literature.

Antimycobacterial activity in a single-cell infection assay of ellagitannins from Combretum aculeatum and their bioavailable metabolites

ETHNOPHARMACOLOGICAL RELEVANCE

The water decoction of Combretum aculeatum aerial parts is traditionally used in Senegal to treat tuberculosis (TB). The extract shows significant antimycobacterial activity in a validated single-cell infection assay.

AIM OF THE STUDY

The main aim of this study was to identify the antimycobacterial compounds in the water decoction of Combretum aculeatum. Since the traditional preparations are used orally, a bioactivity assessment of the possible bioavailable human metabolites was also performed.

MATERIALS AND METHODS

The Combretum aculeatum water decoction extract was first fractionated by flash chromatography. The fractions were submitted to an antibiotic assay against Mycobacterium marinum and to a single-cell infection assay involving Acanthamoeba castellanii as a host. Using these approaches, it was possible to correlate the antimycobacterial activity with two zones of the chromatogram. In parallel with this liquid chromatography (LC)-based activity profiling, high-resolution mass spectrometry (UHPLC-HRMS/MS) revealed the presence of ellagitannin (Et) derivatives in the active zones of the chromatogram. Isolation of the active compounds was performed by preparative chromatography. The structures of the isolated compounds were elucidated by nuclear magnetic resonance (NMR). Additionally, the main human metabolites of commercially available Ets were biologically evaluated in a similar manner.

RESULTS

The in vitro bioassay-guided isolation of the Combretum aculeatum water extract led to the identification of three Ets (1-3) and ellagic acid (4). The major compounds 2 and 3 (α- and β-punicalagin, respectively), exhibited anti-infective activity with an IC₅₀ of 51.48 μM. In view of the documented intestinal metabolism of these compounds, some metabolites, namely, urolithin A (5), urolithin B (6) and urolithin D (7), were investigated for their antimycobacterial activity in the two assays. Urolithin D (7) exhibited the strongest anti-infective activity, with an IC₅₀ of 345.50 μM, but this was moderate compared to the positive control rifampin (IC₅₀ of 6.99 μM). The compounds assayed had no observable cytotoxicity towards the amoeba host cells at concentrations lower than 200 μg/mL.

CONCLUSION

The observed antimycobacterial properties of the traditional water decoction of Combretum aculeatum might be related to the activity of Ets derivatives (1-3) and their metabolites, such as ellagic acid (4) and urolithin D (7). Despite the relatively weak activity of these metabolites, the high consumption of tannins achieved by taking the usual traditional decoction doses should lead to an important increase in the plasmatic concentrations of these active and bioavailable metabolites. These results support to some extent the traditional use of Combretum aculeatum to treat tuberculosis.

Antimycobacterial Activity and Safety Profile Assessment of Alpinia galanga and Tinospora cordifolia

Tuberculosis (TB) remains a common deadly infectious disease and worldwide a major health problem. The current study was therefore designed to investigate the in vitro antimycobacterial activity of different extracts of Alpinia galanga and Tinospora cordifolia. Moreover, a safety assessment for both plants was carried out. Dichloromethane and ethanolic extracts of each plant were examined against H37Rv INH-sensitive and resistant INH strains of Mycobacterium tuberculosis. The safety assessment of both plants has been performed through in vivo acute and chronic toxicity studies in animal model. Body weight, food consumption, water intake, organ's weight, and haematological and biochemical parameters of blood and serum were evaluated. The extracts of A. galanga and T. cordifolia produced significant and dose-dependent inhibitory activity with maximum effect of 18-32% at 50 μg/ml against both strains of M. tuberculosis. No effect on the body weight or food and water consumption was observed but A. galanga caused significantly an increase in the relative weight of the heart, liver, spleen, and kidney. Haematological studies of both plants revealed a slight but significant fall in the RBC and WBC level as well as haemoglobin and platelets. In addition, A. galanga extracts increased significantly liver enzymes and bilirubin and glucose.