Exploration of nature's chemodiversity: the role of secondary metabolites as leads in drug development

Unsaturated fatty acid, Nonacosenoic acid isolated from an endophyte Chaetomium nigricolor inhabiting the stem of Catharanthus roseus and its bioactivity

The endophytic fungus Chaetomium nigricolor culture filtrate's hexane extract was used to identify a cytotoxic very long-chain fatty acid. Based on multiple spectroscopic investigations, the structure of the compound was predicted to be an unsaturated fatty acid, Nonacosenoic acid (NA). Using the MTT assay, the compound's cytotoxic potential was evaluated against MCF-7, A-431, U-251, and HEK-293 T cells. The compound was moderately cytotoxic to breast carcinoma cell line, MCF-7 cells and negligibly cytotoxic to non-cancerous cell line HEK-293 T cells. The compound exhibited mild cytotoxic activity against A-431 and U-251 cells. The compound also induced ROS generation and mitochondrial depolarization in MCF-7 cells when assessed via the NBT and JC-1 assays, respectively. This is the first report on the production of nonacosenoic acid from the endophytic fungus Chaetomium nigricolor and the assessment of its bioactivity.

Improved Long-Term Preservation of Cannabis Inflorescence by Utilizing Integrated Pre-Harvest Hexanoic Acid Treatment and Optimal Post-Harvest Storage Conditions

The effort to maintain cannabinoid and terpene levels in harvested medicinal cannabis inflorescence is crucial, as many studies demonstrated a significant concentration decrease in these compounds during the drying, curing, and storage steps. These stages are critical for the preparation and preservation of medicinal cannabis for end-use, and any decline in cannabinoid and terpene content could potentially reduce the therapeutic efficacy of the product. Consequently, in the present study, we determined the efficacy of pre-harvest hexanoic acid treatment alongside four months of post-harvest vacuum storage in prolonging the shelf life of high THCA cannabis inflorescence. Our findings indicate that hexanoic acid treatment led to elevated concentrations of certain cannabinoids and terpenes on the day of harvest and subsequent to the drying and curing processes. Furthermore, the combination of hexanoic acid treatment and vacuum storage yielded the longest shelf life and the highest cannabinoid and mono-terpene content as compared to all other groups studied. Specifically, the major cannabinoid's-(-)-Δ9-trans-tetrahydrocannabinolic acid (THCA)-concentration decreased by 4-23% during the four months of storage with the lowest reduction observed following hexanoic acid pre-harvest treatment and post-harvest vacuum storage. Hexanoic acid spray application displayed a more pronounced impact on mono-terpene preservation than storage under vacuum without hexanoic acid treatment. Conversely, sesqui-terpenes were observed to be less prone to degradation than mono-terpenes over an extended storage duration. In summation, appropriate pre-harvest treatment coupled with optimized storage conditions can significantly extend the shelf life of cannabis inflorescence and preserve high active compound concentration over an extended time period.

Medicinal Plants against Viral Infections: A Review of Metabolomics Evidence for the Antiviral Properties and Potentials in Plant Sources

Most plants have developed unique mechanisms to cope with harsh environmental conditions to compensate for their lack of mobility. A key part of their coping mechanisms is the synthesis of secondary metabolites. In addition to their role in plants' defense against pathogens, they also possess therapeutic properties against diseases, and their use by humans predates written history. Viruses are a unique class of submicroscopic agents, incapable of independent existence outside a living host. Pathogenic viruses continue to pose a significant threat to global health, leading to innumerable fatalities on a yearly basis. The use of medicinal plants as a natural source of antiviral agents has been widely reported in literature in the past decades. Metabolomics is a powerful research tool for the identification of plant metabolites with antiviral potentials. It can be used to isolate compounds with antiviral capacities in plants and study the biosynthetic pathways involved in viral disease progression. This review discusses the use of medicinal plants as antiviral agents, with a special focus on the metabolomics evidence supporting their efficacy. Suggestions are made for the optimization of various metabolomics methods of characterizing the bioactive compounds in plants and subsequently understanding the mechanisms of their operation.

GCMS characterization and biological potential of the seeds and aerial part of Galium tricorne Stokes

Abstract Natural products have long been proven very effective against various challenging diseases including cancer and bacterial infections. Galium tricorne is one of the important source of natural products, which has not been explored till date in spite of its profound ethnomedicinal prominence. The current study has been designed to explore the biological potential of G. tricorne and to extract and isolate chemical constituents from its aerial part and seeds respectively along with identification of their chemical constituents. Phytochemical screening was performed to figure out the presence of secondary metabolite in G. tricorne. Crude Methanolic extract (Gt.Crd), which was obtained from the aerial part while the fatty acids were extracted from the seeds, which were later on analyzed by GCMS. Similarly, Well Diffusion and MTT method were used for antibacterial activity and cancer cell line assay respectively. To evaluate the cytotoxic potential, brine shrimps were used. Likewise, in Gas Chromatography-Mass Spectroscopy (GC-MS) analysis a total number of 23 compounds were identified in Gt.Crd extract out of which 7 compounds were sorted out to have some sort of toxicity profile. In the same fashion, 5 fatty acids were identified in the seeds of G. tricorne. Moreover, among the fractions, chloroform fraction (Gt.Chf) exhibited greater zone of inhibition (ZOI) 20.37 mm followed by Gt.Crd 18.40 mm against S. aureus and S. pyogenes respectively. In cytotoxicity Gt.Chf was more active followed by ethyl acetate fraction (Gt.Eta) by exhibiting 88.32±0.62% (LC50=60 µg/mL) and 73.95±2.25% (LC50=80 µg/mL) respectively at 1000 µg/mL concentration of the tested sample. Gt.Chf exhibited greater cell line inhibitory activity (IC50=61 µg/mL) against HeLa cell line. Similarly, Gt.Crd displayed IC50 values of 167.84 µg/mL and 175.46 µg/mL against HeLa and NIH/3T3 cell line respectively. Based on the literature review and screenings, it may be concluded that the aerial part and seeds of G. tricorne are the rich sources of bioactive compounds. The results of the current study also authenticate the scientific background for the ethnomedicinal uses of G. tricorne.

New Therapeutic Strategies for Obesity and Its Metabolic Sequelae: Brazilian Cerrado as a Unique Biome

Brazil has several important biomes holding impressive fauna and flora biodiversity. Cerrado being one of the richest ones and a significant area in the search for new plant-based products, such as foods, cosmetics, and medicines. The therapeutic potential of Cerrado plants has been described by several studies associating ethnopharmacological knowledge with phytochemical compounds and therapeutic effects. Based on this wide range of options, the Brazilian population has been using these medicinal plants (MP) for centuries for the treatment of various health conditions. Among these, we highlight metabolic diseases, namely obesity and its metabolic alterations from metabolic syndrome to later stages such as type 2 diabetes (T2D). Several studies have shown that adipose tissue (AT) dysfunction leads to proinflammatory cytokine secretion and impaired free fatty acid (FFA) oxidation and oxidative status, creating the basis for insulin resistance and glucose dysmetabolism. In this scenario, the great Brazilian biodiversity and a wide variety of phytochemical compounds make it an important candidate for the identification of pharmacological strategies for the treatment of these conditions. This review aimed to analyze and summarize the current literature on plants from the Brazilian Cerrado that have therapeutic activity against obesity and its metabolic conditions, reducing inflammation and oxidative stress.

Spatially resolved detection of small molecules from press-dried plant tissue using MALDI imaging

Premise

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is a chemical imaging method that can visualize spatial distributions of particular molecules. Plant tissue imaging has so far mostly used cryosectioning, which can be impractical for the preparation of large-area imaging samples, such as full flower petals. Imaging unsectioned plant tissue presents its own difficulties in extracting metabolites to the surface due to the waxy cuticle.

Methods

We address this by using established delipidation techniques combined with a solvent vapor extraction prior to applying the matrix with many low-concentration sprays.

Results

Using this procedure, we imaged tissue from three different plant species (two flowers and one carnivorous plant leaf). Material factorization analysis of the resulting data reveals a wide range of plant-specific small molecules with varying degrees of localization to specific portions of the tissue samples, while facilitating detection and removal of signal from background sources.

Conclusions

This work demonstrates applicability of MALDI-MSI to press-dried plant samples without freezing or cryosectioning, setting the stage for spatially resolved molecule identification. Increased mass resolution and inclusion of tandem mass spectrometry are necessary next steps to allow more specific and reliable compound identification.

Antimicrobial and Antioxidant Activities of Endophytic Fungi Associated with Arrabidaea chica (Bignoniaceae)

The endophytic fungal community of the Amazonian medicinal plant Arrabidaea chica (Bignoniaceae) was evaluated based on the hypothesis that microbial communities associated with plant species in the Amazon region may produce metabolites with interesting bioactive properties. Therefore, the antimicrobial and antioxidant activities of the fungal extracts were investigated. A total of 107 endophytic fungi were grown in liquid medium and the metabolites were extracted with ethyl acetate. In the screening of fungal extracts for antimicrobial activity, the fungus identified as Botryosphaeria mamane CF2-13 was the most promising, with activity against E. coli, S. epidermidis, P. mirabilis, B. subtilis, S. marcescens, K. pneumoniae, S. enterica, A. brasiliensis, C. albicans, C. tropicalis and, especially, against S. aureus and C. parapsilosis (MIC = 0.312 mg/mL). Screening for antioxidant potential using the DPPH elimination assay showed that the Colletotrichum sp. CG1-7 endophyte extract exhibited potential activity with an EC50 of 11 µg/mL, which is equivalent to quercetin (8 µg/mL). The FRAP method confirmed the antioxidant potential of the fungal extracts. The presence of phenolic compounds and flavonoids in the active extracts was confirmed using TLC. These results indicate that two of the fungi isolated from A. chica exhibit significant antimicrobial and antioxidant potential.

Regulation of the regulators: Transcription factors controlling biosynthesis of plant secondary metabolites during biotic stresses and their regulation by miRNAs

Biotic stresses threaten to destabilize global food security and cause major losses to crop yield worldwide. In response to pest and pathogen attacks, plants trigger many adaptive cellular, morphological, physiological, and metabolic changes. One of the crucial stress-induced adaptive responses is the synthesis and accumulation of plant secondary metabolites (PSMs). PSMs mitigate the adverse effects of stress by maintaining the normal physiological and metabolic functioning of the plants, thereby providing stress tolerance. This differential production of PSMs is tightly orchestrated by master regulatory elements, Transcription factors (TFs) express differentially or undergo transcriptional and translational modifications during stress conditions and influence the production of PSMs. Amongst others, microRNAs, a class of small, non-coding RNA molecules that regulate gene expression post-transcriptionally, also play a vital role in controlling the expression of many such TFs. The present review summarizes the role of stress-inducible TFs in synthesizing and accumulating secondary metabolites and also highlights how miRNAs fine-tune the differential expression of various stress-responsive transcription factors during biotic stress.

Anticancer plant-derivatives: deciphering their oncopreventive and therapeutic potential in molecular terms

Background

Over the years, phytomedicines have been widely used as natural modalities for the treatment and prevention of various diseases by different ethnic groups across the globe. Although, 25% of drugs in the USA contain at least one plant-derived therapeutic compound, currently there is a paucity of plant-derived active medicinal ingredients in the pharmaceutical industry. Scientific evidence-based translation of plant-derived ethnomedicines for their clinical application is an urgent need. The anticancer and associated properties (antioxidative, anti-inflammatory, pro-apoptotic and epithelial-mesenchymal transition (EMT) inhibition) of various plant extracts and phytochemicals have been elucidated earlier. Several of the plant derivatives are already in use under prophylactic/therapeutic settings against cancer and many are being investigated under different phases of clinical trials.

Main body

The purpose of this study is to systematically comprehend the progress made in the area of prophylactic and therapeutic potential of the anticancerous plant derivatives. Besides, we aim to understand their anticancer potential in terms of specific sub-phenomena, such as anti-oxidative, anti-inflammatory, pro-apoptotic and inhibition of EMT, with an insight of the molecules/pathways associated with them. The study also provides details of classes of anticancer compounds, their plant source(s) and the molecular pathway(s) targeted by them. In addition to the antioxidative and antiproliferative potentials of anticancer plant derivatives, this study emphasizes on their EMT-inhibition potential and other ‘anticancer related’ properties. The EMT is highlighted as a phenomenon of choice for targeting cancer due to its role in the induction of metastasis and drug resistance. Different phytochemicals in pre-clinical or clinical trials, with promising chemopreventive/anticancer activities have been enlisted and the plant compounds showing synergistic anticancer activity in combination with the existing drugs have been discussed. The review also unravels the need of carrying out pan-signalome studies for identifying the cardinal pathways modulated by phytomedicine(s), as in many cases, the molecular pathway(s) has/have been randomly studied.

Conclusion

This review systematically compiles the studies regarding the impact of various plant derivatives in different cancers and oncogenic processes, as tested in diverse experimental model systems. Availability of more comprehensive information on anticancer phyto-constituents, their relative abundance in crude drugs, pathways/molecules targeted by phytomedicines, their long-term toxicity data and information regarding their safe use under the combinatorial settings, would open greater avenues of their utilization in future against this dreaded disease.

Graphical Abstract

Switching cell fate by the actin-auxin oscillator in Taxus: cellular aspects of plant cell fermentation

Paclitaxel synthesis in Taxus cells correlates with a cell-fate switch that leads to vacuoles of a glossy appearance and vermiform mitochondria. This switch depends on actin and apoplastic respiratory burst. Plant cell fermentation, the production of valuable products in plant cell culture, has great potential as sustainable alternative to the exploitation of natural resources for compounds of pharmaceutical interest. However, the success of this approach has remained limited, because the cellular aspects of metabolic competence are mostly unknown. The production of the anti-cancer alkaloid Paclitaxel has been, so far, the most successful case for this approach. In the current work, we map cellular aspects of alkaloid synthesis in cells of Taxus chinensis using a combination of live-cell imaging, quantitative physiology, and metabolite analysis. We show evidence that metabolic potency correlates with a differentiation event giving rise to cells with large vacuoles with a tonoplast that is of a glossy appearance, agglomerations of lipophilic compounds, and multivesicular bodies that fuse with the plasma membrane. Cellular features of these glossy cells are bundled actin, more numerous peroxisomes, and vermiform mitochondria. The incidence of glossy cells can be increased by aluminium ions, and this increase is significantly reduced by the actin inhibitor Latrunculin B, and by diphenylene iodonium, a specific inhibitor of the NADPH oxidase Respiratory burst oxidase Homologue (RboH). It is also reduced by the artificial auxin Picloram. This cellular fingerprint matches the implications of a model, where the differentiation into the glossy cell type is regulated by the actin-auxin oscillator that in plant cells acts as dynamic switch between growth and defence.

Phytochemical Screening, Quantification, FT-IR Analysis, and In Silico Characterization of Potential Bio-active Compounds Identified in HR-LC/MS Analysis of the Polyherbal Formulation from Northeast India

Diabetes is a group of metabolic disorders characterized by elevated blood sugar levels, leading to many undesirable health consequences. There are many herbal formulations, traditionally used by the Northeast Indian population for disease management. These formulations require scientific validations to optimize their efficacy and increase their popularity. In this study, we attempt to scientifically validate a polyherbal formulation traditionally used for the management of diabetes through preliminary phytochemicals investigation, characterization of potential phytochemicals using Fourier transform infrared (FT-IR) spectroscopy, high-resolution liquid chromatography mass spectrometry (HR-LC/MS) analysis, and in silico characterization of physiochemical, drug-likeness, and pharmacokinetic properties of identified phytochemical compounds. Qualitative phytochemical screening of various extracts of the formulation confirmed the presence of alkaloids, phenols and tannins, flavonoids, fats, and oils. Phytochemical quantification of the various extracts showed that the highest total phenolic content is present in the ethanolic extract (35.61 ± 0.15 mg GAE/g), while the highest total flavonoid content is present in the chloroform extract (76.33 ± 2.96 mg QE/g) of the formulation. FT-IR spectroscopic analysis revealed various characteristic band values with various functional groups in the formulation extract such as amines, alcohol, fluoro compounds, phenol, alkane, alkene, and conjugated acid groups. HR-LC/MS analyses identified nearly 51 compounds including 9 small peptides and 42 potential phytochemical compounds. In silico SwissADME analysis of identified compounds revealed 25 potential compounds following Lipinski's rule and showing drug-like characteristics, and out of them, 16 compounds exhibited good oral bioavailability, as revealed in the bioavailability radar. The overall study showed that the presented polyherbal formulation is enriched with bio-active phytochemical compounds with good pharmaceutical values.

Trivialities in metabolomics: Artifacts in extraction and analysis

The aim of this review is to show the risks of artifact formation in metabolomics analyses. Metabolomics has developed in a major tool in system biology approaches to unravel the metabolic networks that are the basis of life. Presently TLC, LC-MS, GC-MS, MS-MS and nuclear magnetic resonance are applied to analyze the metabolome of all kind of biomaterials. These analytical methods require robust preanalytical protocols to extract the small molecules from the biomatrix. The quality of the metabolomics analyses depends on protocols for collecting and processing of the biomaterial, including the methods for drying, grinding and extraction. Also the final preparation of the samples for instrumental analysis is crucial for highly reproducible analyses. The risks of artifact formation in these steps are reviewed from the point of view of the commonly used solvents. Examples of various artifacts formed through chemical reactions between solvents or contaminations with functional groups in the analytes are discussed. These reactions involve, for example, the formation of esters, trans-esterifications, hemiacetal and acetal formation, N-oxidations, and the formation of carbinolamines. It concerns chemical reactions with hydroxyl-, aldehyde-, keto-, carboxyl-, ester-, and amine functional groups. In the analytical steps, artifacts in LC may come from the stationary phase or reactions of the eluent with analytes. Differences between the solvent of the injected sample and the LC-mobile phase may cause distortions of the retention of analytes. In all analytical methods, poorly soluble compounds will be in all samples at saturation level, thus hiding a potential marker function. Finally a full identification of compounds remains a major hurdle in metabolomics, it requires a full set of spectral data, including methods for confirming the absolute stereochemistry. The putative identifications found in supplemental data of many studies, unfortunately, often become “truly” identified compounds in papers citing these results. Proper validation of the protocols for preanalytical and analytical procedures is essential for reproducible analyses in metabolomics.

α-Glucosidase, α-Amylase and Antioxidant Evaluations of Isolated Bioactives from Wild Strawberry

Diabetes mellitus is a metabolic disorder and is a global challenge to the current medicinal chemists and pharmacologists. This research has been designed to isolate and evaluate antidiabetic bioactives from Fragaria indica. The crude extracts, semi-purified and pure bioactives have been used in all in vitro assays. The in vitro α-glucosidase, α-amylase and DPPH free radical activities have been performed on all plant samples. The initial activities showed that ethyl acetate (Fi.EtAc) was the potent fraction in all the assays. This fraction was initially semi-purified to obtain Fi.EtAc 1–3. Among the semi-purified fractions, Fi.EtAc 2 was dominant, exhibiting potent IC₅₀ values in all the in vitro assays. Based on the potency and availability of materials, Fi.EtAc 2 was subjected to further purification to obtain compounds 1 (2,4-dichloro-6-hydroxy-3,5-dimethoxytoluene) and 2 (2-methyl-6-(4-methylphenyl)-2-hepten-4-one). The two isolated compounds were characterized by mass and NMR analyses. The compounds 1 and 2 showed excellent inhibitions against α-glucosidase (21.45 for 1 and 15.03 for 2 μg/mL), α-amylase (17.65 and 16.56 μg/mL) and DPPH free radicals (7.62 and 14.30 μg/mL). Our study provides baseline research for the antidiabetic bioactives exploration from Fragaria indica. The bioactive compounds can be evaluated in animals-based antidiabetic activity in future.

High-Yield Production of a Rich-in-Hydroxytyrosol Extract from Olive (Olea europaea) Leaves

The aim of the present study was to explore the high-yield production of hydroxytyrosol, a phenolic compound with very high antioxidant capacity. Olea europaea leaves were chosen as feedstock as they contain significant amounts of oleuropein, which can be hydrolyzed to hydroxytyrosol. The chosen techniques are widely used in the industry and can be easily scaled up. Olive leaves underwent drying and mechanical pretreatment and extractives were transported to a solvent by solid–liquid extraction using water–ethanol mixtures. The use of approximately 60–80% ethanol showed an almost 2-fold increase in extracted phenolics compared to pure water, to approximately 45 g/kg of dry leaves. Extracted oleuropein was hydrolyzed with hydrochloric acid and the hydrolysate was extracted with ethyl acetate after pH adjustment. This step led to a hydroxytorosol content increase from less than 4% to approximately 60% w/w of dry extract, or 10–15 g of hydroxytyrosol recovery per kg of dry leaves.

A Treatment to Cure Diabetes Using Plant-Based Drug Discovery

The field of peptides and proteins has opened up new doors for plant-based medication development because of analytical breakthroughs. Enzymatic breakdown of plant-specific proteins yields bioactive peptides. These plant-based proteins and peptides, in addition to their in vitro and vivo outcomes for diabetes treatment, are discussed in this study. The secondary metabolites of vegetation can interfere with the extraction, separation, characterization, and commercialization of plant proteins through the pharmaceutical industry. Glucose-lowering diabetic peptides are a hot commodity. For a wide range of illnesses, bioactive peptides from flora can offer up new avenues for the development of cost-effective therapy options.

Isolation and biological activity of azocine and azocane alkaloids

Thousands of known alkaloids contain a nitrogen (N) heterocycle. While five-, six- and seven-membered N-heterocycles (ie: pyrroles, imidazoles, indoles, pyridines and azepines and their saturated variants) are common, those with an eight-membered N-heterocycle are comparatively rare. This review discusses the structure and bioactivity of alkaloids that contain an azocine (or saturated azocane) ring, and the array of sources whence they originate.

Towards Advances in Medicinal Plant Antimicrobial Activity: A Review Study on Challenges and Future Perspectives

The increasing incidence of drug- resistant pathogens raises an urgent need to identify and isolate new bioactive compounds from medicinal plants using standardized modern analytical procedures. Medicinal plant-derived compounds could provide novel straightforward approaches against pathogenic bacteria. This review explores the antimicrobial activity of plant-derived components, their possible mechanisms of action, as well as their chemical potential. The focus is put on the current challenges and future perspectives surrounding medicinal plants antimicrobial activity. There are some inherent challenges regarding medicinal plant extracts and their antimicrobial efficacy. Appropriate and optimized extraction methodology plant species dependent leads to upgraded and selective extracted compounds. Antimicrobial susceptibility tests for the determination of the antimicrobial activity of plant extracts may show variations in obtained results. Moreover, there are several difficulties and problems that need to be overcome for the development of new antimicrobials from plant extracts, while efforts have been made to enhance the antimicrobial activity of chemical compounds. Research on the mechanisms of action, interplay with other substances, and the pharmacokinetic and/or pharmacodynamic profile of the medicinal plant extracts should be given high priority to characterize them as potential antimicrobial agents.

Total Synthesis and Determination of the Absolute Configuration of Rakicidin C

The absolute configuration of rakicidin C was predicted by comparison of optical rotation data and absolute configuration of APD-cyclic depsipeptides and further determined by total synthesis. The absolute configuration of five chiral centers was determined as 2R, 15R, 16R, 17S, and 19S. Our efficient route involves 19 longest linear steps with an overall yield of 1.49%.

Salt Stress Mitigation via the Foliar Application of Chitosan-Functionalized Selenium and Anatase Titanium Dioxide Nanoparticles in Stevia (Stevia rebaudiana Bertoni)

High salt levels are one of the significant and major limiting factors on crop yield and productivity. Out of the available attempts made against high salt levels, engineered nanoparticles (NPs) have been widely employed and considered as effective strategies in this regard. Of these NPs, titanium dioxide nanoparticles (TiO₂ NPs) and selenium functionalized using chitosan nanoparticles (Cs–Se NPs) were applied for a quite number of plants, but their potential roles for alleviating the adverse effects of salinity on stevia remains unclear. Stevia (Stevia rebaudiana Bertoni) is one of the reputed medicinal plants due to their diterpenoid steviol glycosides (stevioside and rebaudioside A). For this reason, the current study was designed to investigate the potential of TiO₂ NPs (0, 100 and 200 mg L⁻¹) and Cs–Se NPs (0, 10 and 20 mg L⁻¹) to alleviate salt stress (0, 50 and 100 mM NaCl) in stevia. The findings of the study revealed that salinity decreased the growth and photosynthetic traits but resulted in substantial cell damage through increasing H₂O₂ and MDA content, as well as electrolyte leakage (EL). However, the application of TiO₂ NPs (100 mg L⁻¹) and Cs–Se NPs (20 mg L⁻¹) increased the growth, photosynthetic performance and activity of antioxidant enzymes, and decreased the contents of H₂O₂, MDA and EL under the saline conditions. In addition to the enhanced growth and physiological performance of the plant, the essential oil content was also increased with the treatments of TiO₂ (100 mg L⁻¹) and Cs–Se NPs (20 mg L⁻¹). In addition, the tested NPs treatments increased the concentration of stevioside (in the non-saline condition and under salinity stress) and rebaudioside A (under the salinity conditions) in stevia plants. Overall, the current findings suggest that especially 100 mg L⁻¹ TiO₂ NPs and 20 mg L⁻¹ Cs–Se could be considered as promising agents in combating high levels of salinity in the case of stevia.

Optimising the use of gene expression data to predict plant metabolic pathway memberships

Plant metabolites from diverse pathways are important for plant survival, human nutrition and medicine. The pathway memberships of most plant enzyme genes are unknown. While co-expression is useful for assigning genes to pathways, expression correlation may exist only under specific spatiotemporal and conditional contexts. Utilising > 600 tomato (Solanum lycopersicum) expression data combinations, three strategies for predicting memberships in 85 pathways were explored. Optimal predictions for different pathways require distinct data combinations indicative of pathway functions. Naive prediction (i.e. identifying pathways with the most similarly expressed genes) is error prone. In 52 pathways, unsupervised learning performed better than supervised approaches, possibly due to limited training data availability. Using gene-to-pathway expression similarities led to prediction models that outperformed those based simply on expression levels. Using 36 experimental validated genes, the pathway-best model prediction accuracy is 58.3%, significantly better compared with that for predicting annotated genes without experimental evidence (37.0%) or random guess (1.2%), demonstrating the importance of data quality. Our study highlights the need to extensively explore expression-based features and prediction strategies to maximise the accuracy of metabolic pathway membership assignment. The prediction framework outlined here can be applied to other species and serves as a baseline model for future comparisons.

Metabolic and Epigenetics Action Mechanisms of Antiobesity Medicinal Plants and Phytochemicals

Ever-growing research efforts are demonstrating the potential of medicinal plants and their phytochemicals to prevent and manage obesity, either individually or synergistically. Multiple combinations of phytochemicals can result in a synergistic activity that increases their beneficial effects at molecular, cellular, metabolic, and temporal levels, offering advantages over chemically synthesized drug-based treatments. Herbs and their derived compounds have the potential for controlling appetite, inhibiting pancreatic lipase activity, stimulating thermogenesis and lipid metabolism, increasing satiety, promoting lipolysis, regulating adipogenesis, and inducing apoptosis in adipocytes. Furthermore, targeting adipocyte life cycle using various dietary bioactives that affect different stages of adipocyte life cycle represents also an important target in the development of new antiobesity drugs. In this regard, different stages of adipocyte development that are targeted by antiobesity drugs can include preadipocytes, maturing preadipocytes, and mature adipocytes. Various herbal-derived active compounds, such as capsaicin, genistein, apigenin, luteolin, kaempferol, myricetin, quercetin, docosahexaenoic acid, quercetin, resveratrol, and ajoene, affect adipocytes during specific stages of development, resulting in either inhibition of adipogenesis or induction of apoptosis. Although numerous molecular targets that can be used for both treatment and prevention of obesity have been identified, targeted single cellular receptor or pathway has resulted in limited success. In this review, we discuss the state-of-the-art knowledge about antiobesity medicinal plants and their active compounds and their effects on several cellular, molecular, and metabolic pathways simultaneously with multiple phytochemicals through synergistic functioning which might be an appropriate approach to better management of obesity. In addition, epigenetic mechanisms (acetylation, methylation, miRNAs, ubiquitylation, phosphorylation, and chromatin packaging) of phytochemicals and their preventive and therapeutic perspective are explored in this review.

NMR Profiling of Ononis diffusa Identifies Cytotoxic Compounds against Cetuximab-Resistant Colon Cancer Cell Lines

In the search of new natural products to be explored as possible anticancer drugs, two plant species, namely Ononis diffusa and Ononis variegata, were screened against colorectal cancer cell lines. The cytotoxic activity of the crude extracts was tested on a panel of colon cancer cell models including cetuximab-sensitive (Caco-2, GEO, SW48), intrinsic (HT-29 and HCT-116), and acquired (GEO-CR, SW48-CR) cetuximab-resistant cell lines. Ononis diffusa showed remarkable cytotoxic activity, especially on the cetuximab-resistant cell lines. The active extract composition was determined by NMR analysis. Given its complexity, a partial purification was then carried out. The fractions obtained were again tested for their biological activity and their metabolite content was determined by 1D and 2D NMR analysis. The study led to the identification of a fraction enriched in oxylipins that showed a 92% growth inhibition of the HT-29 cell line at a concentration of 50 µg/mL.

Antibacterial activity of selected invertebrate species

The evolution of multiple-drug resistant bacteria is contributing to the global antimicrobial crisis, hence driving us to search for novel antimicrobial(s). Among animals, invertebrates represent up to 80% of all known species suggesting their wide distribution. Despite their ubiquitous and plentiful nature, they have been largely unexplored as potential source of antibacterials. In this study, we selected a broad range of invertebrates from terrestrial and marine environments and tested their lysates for antibacterial activity against methicillin-resistant Staphylococcus aereus (MRSA) and neuropathogenic Escherichia coli K1. Cockroaches, centipedes, tarantulas, prawns, lobster, and mud crabs showed antibacterial activity with selected lysates exhibiting more than 90% bactericidal effects. The red-headed centipede's hemolymph showed 90% and 50% bacteriostatic activity against MRSA and E. coli K1, respectively. Tarantula's body extracts exhibited antibacterial activity against MRSA and E. coli K1. Gut extracts of tiger prawn exhibited more than 90% bacteriostatic activity against both bacteria. The selected lobster and mud crab extract exhibited up to 90% growth inhibitory activity against MRSA. Overall, these results showed that selected invertebrates are an untapped source of broad-spectrum antibacterial activity and suggest the presence of biologically active molecules.

Cicadidae Periostracum Attenuates Atopic Dermatitis Symptoms and Pathology via the Regulation of NLRP3 Inflammasome Activation

Atopic dermatitis (AD) is a multifactorial inflammatory skin disease of complex etiology. Despite its increasing prevalence, treatment for AD is still limited. Crude drugs, including herbal extracts or natural resources, are being used to treat AD symptoms, with minimum side effects. Cicadidae Periostracum (CP), derived from the slough of insects belonging to the family Cicadidae, is a commonly used crude drug in traditional Asian medicine to treat/control epilepsy, shock, and edema. However, the effect of CP on AD-like skin lesions is unknown. In this study, we examined the effect of a CP water extract on AD disease development in vivo, using a house dust mite-induced AD mouse model, and in vitro, using HaCaT keratinocytes and a 3D human skin equivalent system. Importantly, CP administration alleviated house dust mite-induced AD-like symptoms, suggested by the quantified dermatitis scores, animal scratching behaviors, skin moisture retention capacity, and skin lesion and ear thickness. Furthermore, histopathological analysis demonstrated that CP decreased intralesional mast cell infiltration. In addition, CP treatments decreased the systemic levels of immunoglobulin E, histamine, and thymic stromal lymphopoietin (TSLP) and the local mRNA expression of TSLP and several Th1/Th2 cytokines. Our data suggest that these effects were mediated by the inhibition of nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome activation. In vivo and in vitro CP treatments resulted in the downregulation of inflammasome components, such as ASC and cleaved caspase-1, as well as related mediators such as IL-1β and reactive oxygen species. Collectively, our results suggest that CP is a potential therapeutic agent for AD, controlling inflammatory responses through the suppression of NLRP3 inflammasome activation.

Advances in the discovery and development of anthelmintics by harnessing natural product scaffolds

Widespread resistance to currently-used anthelmintics represents a major obstacle to controlling parasitic nematodes of livestock animals. Given the reliance on anthelmintics in many control regimens, there is a need for the continued discovery and development of new nematocides. Enabling such a focus are: (i) the major chemical diversity of natural products; (ii) the availability of curated, drug-like extract-, fraction- and/or compound-libraries from natural sources; (iii) the utility and practicality of well-established whole-worm bioassays for Haemonchus contortus-an important parasitic nematodes of livestock-to screen natural product libraries; and (iv) the availability of advanced chromatographic (HPLC), spectroscopic (NMR) and spectrometric (MS) techniques for bioassay-guided fractionation and structural elucidation. This context provides a sound basis for the identification and characterisation of anthelmintic candidates from natural sources. This chapter provides a background on the importance and impact of helminth infections/diseases, parasite control and aspects of drug discovery, and reviews recent work focused on (i) screening well-defined compound libraries to establish the methods needed for large-scale screening of natural extract libraries; (ii) discovering plant and marine extracts with nematocidal or nematostatic activity, and purifying bioactive compounds and assessing their potential for further development; and (iii) synthesising analogues of selected purified natural compounds for the identification of possible 'lead' candidates. The chapter describes some lessons learned from this work and proposes future areas of focus for drug discovery. Collectively, the findings from this recent work show potential for selected natural product scaffolds as candidates for future development. Developing such candidates via future chemical optimisation, efficacy and safety evaluations, broad spectrum activity assessments, and target identification represents an exciting prospect and, if successful, could pave the way to subsequent pre-clinical and clinical evaluations.

Flavonoids and Related Members of the Aromatic Polyketide Group in Human Health and Disease: Do They Really Work?

Some aromatic polyketides such as dietary flavonoids have gained reputation as miraculous molecules with preeminent beneficial effects on human health, for example, as antioxidants. However, there is little conclusive evidence that dietary flavonoids provide significant leads for developing more effective drugs, as the majority appears to be of negligible medicinal importance. Some aromatic polyketides of limited distribution have shown more interesting medicinal properties and additional research should be focused on them. Combretastatins, analogues of phenoxodiol, hepatoactive kavalactones, and silymarin are showing a considerable promise in the advanced phases of clinical trials for the treatment of various pathologies. If their limitations such as adverse side effects, poor water solubility, and oral inactivity are successfully eliminated, they might be prime candidates for the development of more effective and in some case safer drugs. This review highlights some of the newer compounds, where they are in the new drug pipeline and how researchers are searching for additional likely candidates.

So Uncommon and so Singular, but Underexplored: An Updated Overview on Ethnobotanical Uses, Biological Properties and Phytoconstituents of Sardinian Endemic Plants

The last decades have recorded an increase of plant-based drug discovery processes. Indeed, natural products possess a superior chemical diversity as compared to synthetic ones, leading to a renewal in searching for new therapeutic agents from the plant kingdom. In particular, since the structural variety of natural compounds reflects the biodiversity of their source organisms, regions of the world with high biodiversity and endemism deserve particular interest. In this context, Sardinia Island (Italy), with 290 endemic taxa (12% of the total flora), is expected to provide unique and structurally diverse phytochemicals for drug development. Several research groups built up a large program dedicated to the analysis of Sardinian endemic species, highlighting their peculiar features, both in respect of phytochemical and biological profiles. On this basis, the aim of this review is to provide an up-to-date and comprehensive overview on ethnobotanical uses, biological properties and phytoconstituents of Sardinian endemic plants in order to support their beneficial potential and to provide input for future investigations. We documented 152 articles published from 1965 to June 2020 in which a broad range of biological activities and the identification of previously undescribed compounds have been reported, supporting their great value as sources of therapeutic agents.

Computational systems biology of cellular processes in Arabidopsis thaliana: an overview

Systems biology strives for gaining an understanding of biological phenomena by studying the interactions of different parts of a system and integrating the knowledge obtained into the current view of the underlying processes. This is achieved by a tight combination of quantitative experimentation and computational modeling. While there is already a large quantity of systems biology studies describing human, animal and especially microbial cell biological systems, plant biology has been lagging behind for many years. However, in the case of the model plant Arabidopsis thaliana, the steadily increasing amount of information on the levels of its genome, proteome and on a variety of its metabolic and signalling pathways is progressively enabling more researchers to construct models for cellular processes for the plant, which in turn encourages more experimental data to be generated, showing also for plant sciences how fruitful systems biology research can be. In this review, we provide an overview over some of these recent studies which use different systems biological approaches to get a better understanding of the cell biology of A. thaliana. The approaches used in these are genome-scale metabolic modeling, as well as kinetic modeling of metabolic and signalling pathways. Furthermore, we selected several cases to exemplify how the modeling approaches have led to significant advances or new perspectives in the field.

Nanoharvesting of bioactive materials from living plant cultures using engineered silica nanoparticles

Plant secondary metabolites are valuable therapeutics not readily synthesized by traditional chemistry techniques. Although their enrichment in plant cell cultures is possible following advances in biotechnology, conventional methods of recovery are destructive to the tissues. Nanoharvesting, in which nanoparticles are designed to bind and carry biomolecules out of living cells, offers continuous production of metabolites from plant cultures. Here, nanoharvesting of polyphenolic flavonoids, model plant-derived therapeutics, enriched in Solidago nemoralis hairy root cultures, is performed using engineered mesoporous silica nanoparticles (MSNPs, 165 nm diameter and 950 m2/g surface area) functionalized with both titanium dioxide (TiO2, 425 mg/g particles) for coordination binding sites, and amines (NH2, 145 mg/g particles) to promote cellular internalization. Intracellular uptake and localization of the nanoparticles (in Murashige and Skoog media) in hairy roots were confirmed by tagging the particles with rhodamine B isothiocyanate, incubating the particles with hairy roots, and quenching bulk fluorescence using trypan blue. Nanoharvesting of biologically active flavonoids was demonstrated by observing increased antiradical activity (using 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay) by nanoparticles after exposure to hairy roots (indicating general antioxidant activity), and by the displacement of the radio-ligand [3H]-methyllycaconitine from rat hippocampal nicotinic receptors by solutes recovered from nanoharvested particles (indicating pharmacological activity specific to S. nemoralis flavonoids). Post-nanoharvesting growth suggests that the roots are viable after nanoharvesting, and capable of continued flavonoid synthesis. These observations demonstrate the potential for using engineered nanostructured particles to facilitate continuous isolation of a broad range of biomolecules from living and functioning plant cultures.

Antifungal Proteins with Antiproliferative Activity on Cancer Cells and HIV-1 Enzyme Inhibitory Activity from Medicinal Plants and Medicinal Fungi

A variety of fungi, plants, and their different tissues are used in Traditional Chinese Medicine to improve health, and some of them are recommended for dietary therapy. Many of these plants and fungi contain antifungal proteins and peptides which suppress spore germination and hyphal growth in phytopathogenic fungi. The aim of this article is to review antifungal proteins produced by medicinal plants and fungi used in Chinese medicine which also possess anticancer and human immunodeficiency virus-1 (HIV-1) enzyme inhibitory activities.

Medicinal Plant Compounds for Combating the Multi-drug Resistant Pathogenic Bacteria: A Review

BACKGROUND

Globally, people utilize plants as the main source of remedy to heal various ailments. Medicinal plants have been utilized to treat ailments since the invention of modern scientific systems of medicine. The common remedy of infectious diseases mainly depends on the inhibition capacity of compounds or killing potential. The issue may give a clue for the development of a novel antimicrobial agent.

METHODS

Currently, microorganisms which are resistant towards antibiotics are probably a matter of serious concern for the overall well-being of health. At the moment, new therapeutic targets aside from the microorganism wall-based activities are in progress. For instance, the autoinducer molecules produced by the quorum sensing system are used to control antibiotic resistance and biofilm formation.

RESULTS

This therapeutic target is well-studied worldwide, however, the scientific data are not updated and only current studies started to gain insight into its perspective as a target to struggle against infectious diseases. Microbial resistance against antimicrobial compounds is a topic of serious concern in recent time.

CONCLUSION

Hence, this paper aims to confer a current overview of the novel compounds, quorum sensing, quorum quenching, biofilm formation in the development of antibiotic resistance and an update on their importance as a potential target for natural substances.

Plant-Derived Bioactive Peptides: A Treatment to Cure Diabetes

ABSTRACT

Recent advances in analytical techniques have opened new opportunities for plant-based drug discovery in the field of peptide and proteins. Enzymatic hydrolysis of plant parent proteins forms bioactive peptides which are explored in the treatment of various diseases. In this review, we will discuss the identified plant-based bioactive proteins and peptides and the in vitro, in vivo results for the treatment of diabetes. Extraction, isolation, characterization and commercial utilization of plant proteins is a challenge for the pharmaceutical industry as plants contain several interfering secondary metabolites. The market of peptide drugs for the treatment of diabetes is growing at a fast rate. Plant-based bioactive peptides might open up new opportunities to discover economic lead for the management of various diseases.

GRAPHIC ABSTRACT

Carbon-based nanomaterials as stimulators of production of pharmaceutically active alkaloids in cell culture of Catharanthus roseus

Carbon-based nanomaterials (CBNs) were previously described as regulators of plant cell division. Here, we demonstrated the ability of multi-walled carbon nanotubes (MWCNT) and graphene to enhance biomass production in callus culture of the medicinal plant Catharanthus roseus cultivated in dark conditions. Furthermore, both tested CBNs were able to stimulate biosynthesis of total produced alkaloids in CBN-exposed callus culture of Catharanthus. In one case, total alkaloids in CBN-exposed Catharanthus were double that of unexposed Catharanthus. Analysis of metabolites by HPLC revealed that production of the pharmaceutically active alkaloids vinblastine and vincristine was dramatically enhanced in callus exposed to MWCNT or graphene in both dark and light conditions of callus cultivation. In vitro assays (MTT, flow cytometry) demonstrated that total alkaloid extracts derived from Catharanthus callus treated with CBNs significantly reduced cell proliferation of breast cancer (MCF-7) and lung cancer (A549) cell lines compared to the application of extracts derived from untreated Catharanthus callus.

Pregnane Glycosides

Pregnane glycosides constitute a class of compounds widely distributed in the plant kingdom. Many of them have shown either anticarcinogenic or cancer inhibitory properties, besides other useful biological activities. New chromatographic techniques and advances in spectroscopic and spectrometric methods have accelerated the purification and structure determination of novel glycosides of this series. A compilation of the pregnane glycosides isolated from 1995 until the middle of 2005, along with their physical data, structures and occurrence are presented in this review, which also summarizes, with suitable examples, recent developments in isolation and purification techniques, and structural elucidation using modern spectrometric methods like ESIMS and tandem mass spectrometry, and 2D NMR spectroscopic strategies. The reported anticancer and other biological activities of pregnane glycosides are also discussed.

Therapeutic effect of Parmotrema tinctorum against complete Freund's adjuvant-induced arthritis in rats and identification of novel Isophthalic ester derivative

The present study reveals the anti-arthritic potential of traditionally used Parmotrema tinctorum (Pt) on experimental rats and purification of novel Isophthalic ester derivative. Arthritis was induced in rats using Freund's complete adjuvant (CFA) and subsequently treated with Pt extract (100 & 200 mg/kg.b.w). Assessment of antiarthritic activity was carried out using paw volume, arthritic score, haematological, biochemical, tissue antioxidant, histopathology and radiological analyses of ankle joints. The results revealed that continuous administration of Pt reduces the complication associated with arthritis by inhibiting the edema formation and arthritic score significantly (P < 0.05). The altered changes in biochemical parameters were brought back with an improvement in free radical scavenging ability after treatment with Pt significantly. Further purification of Pt using conventional column chromatography led to the isolation of four compounds and the structure of these isolated compounds were elucidated on the basis of spectral data's FT-IR, ¹H NMR, ¹³C NMR, DEPT-NMR spectroscopy, COSY & HSQC-NMR spectroscopy and LC-MS. The spectral data revealed that the three compounds were found to be Methyl-γ-Orsellinate, Atranorin, and usnic acid (CI-III) along with a novel secondary metabolite, (C-IV)4-Hydroxy-5-methyl-isophthalicacid3-(3,4-dihydroxy-5-methyl-phenyl)ester (C₁₆H₁₄O₇,318.1amu). The present study reveals that Parmotrema tinctorum reduces complications associated with arthritis and the compounds were isolated for the first time.

Medicinal plants commonly used against cancer in traditional medicine formulae in Sri Lanka

Cancer is a global burden. In low- and middle-income countries around 70% of deaths are due to cancer. For a number of years natural products have been a good source of agents for combatting cancer and plants have played a huge role in anti-cancer product development. For many centuries, indigenous cultures around the world have used traditional herbal medicine to treat a myriad of diseases including cancer. In Sri Lanka, a number of plants have been reported to have anti-cancer properties and some of the commonly used plants are described in this review with an account of their compounds and modes of action. Only a small number of the plants in Sri Lanka have been tested for their bioactivity and more research is required to determine their medicinal activity with the aim of developing novel drugs to fight this disease.

Diversity and biological activities of endophytic fungi associated with Catharanthus roseus

BACKGROUND

The present study involves diversity and bioactivity of the endophytic fungal community from Catharanthus roseus inhabiting the coastal region. This study has been conducted hypothesizing that the microbial communities in the coastal regions would tolerate a range of abiotic stress such as salinity, humidity, temperature and soil composition, and it may produce new metabolites, which may possess bioactive property. Therefore in the current study, the cytotoxicity and free radical scavenging potential of the fungal organic extracts have been investigated. Moreover, the apoptotic and the antioxidant potential of the fungus that exhibited the best activity in preliminary screening has also been demonstrated.

RESULTS

Twenty endophytic fungal isolates were obtained from different parts of the plant, and identified using internal transcribed spacer region analysis. Based on the colonization frequency, the dominant genera were found to be Colletotrichum, Alternaria and Chaetomium with colonization frequency % of 8.66, 7.00 and 6.33, respectively. It was observed that the species diversity and richness was the highest in bark followed by leaf and stem regions of the plant. On screening the fungal ethyl acetate extracts for cytotoxicity against the HeLa cells, the Chaetomium nigricolor extract exhibited potent cytotoxic activity of 92.20% at 100 μg mL^- 1 concentration. Comparison between the different organic extracts (ethyl acetate, chloroform, dichloromethane and hexane) of Chaetomium nigricolor mycelial and culture filtrate, it was observed that the mycelial as well the culture filtrate ethyl acetate extracts and the culture filtrate hexane extract showed significant cytotoxic potential against the HeLa and MCF-7 cells, respectively. The apoptotic- and mitochondrial membrane depolarisation-induction potential of the Chaetomium nigricolor ethyl acetate extract has also been demonstrated in this study. Further the screening of antioxidant potential of the ethyl acetate fungal extracts using DPPH scavenging assay showed that Chaetomium nigricolor extract exhibited potential activity with a significant EC₅₀ value of 22 μg mL^- 1. The ethyl acetate extract of Chaetomium nigricolor also exhibited superoxide radical scavenging potential.

CONCLUSION

These results indicated that diverse endophytic fungal population inhabits Catharanthus roseus. One of the fungal isolate Chaetomium nigricolor exhibited significant cytotoxic, apoptotic and antioxidant potential.

Essential Oils as Feed Additives-Future Perspectives

The inconsistency of phytogenic feed additives' (PFA) effects on the livestock industry poses a risk for their use as a replacement for antibiotic growth promoters. The livestock market is being encouraged to use natural growth promotors, but information is limited about the PFA mode of action. The aim of this paper is to present the complexity of compounds present in essential oils (EOs) and factors that influence biological effects of PFA. In this paper, we highlight various controls and optimization parameters that influence the processes for the standardization of these products. The chemical composition of EOs depends on plant genetics, growth conditions, development stage at harvest, and processes of extracting active compounds. Their biological effects are further influenced by the interaction of phytochemicals and their bioavailability in the gastrointestinal tract of animals. PFA effects on animal health and production are also complex due to various EO antibiotic, antioxidant, anti-quorum sensing, anti-inflammatory, and digestive fluids stimulating activities. Research must focus on reliable methods to identify and control the quality and effects of EOs. In this study, we focused on available microencapsulation techniques of EOs to increase the bioavailability of active compounds, as well as their application in the animal feed additive industry.

Antimicrobial discovery from natural and unusual sources

OBJECTIVES

Whether vertebrates/invertebrates living in polluted environments are an additional source of antimicrobials.

KEY FINDINGS

Majority of antimicrobials have been discovered from prokaryotes and those which are of eukaryotic origin are derived mainly from fungal and plant sources. With this in mind, it is important to note that pests, such as cockroaches come across pathogenic bacteria routinely, yet thrive in polluted environments. Other animals, such as snakes thrive from feeding on germ-infested rodents. Logically, such species must have developed an approach to protect themselves from these pathogens, yet they have largely been ignored as a potential source of antimicrobials despite their remarkable capability to fight disease-causing organisms.

SUMMARY

Animals living in polluted environments are an underutilized source for potential antimicrobials, hence it is believed that several novel bioactive molecule(s) will be identified from these sources to counter increasingly resistant bacterial infections. Further research will be necessary in the development of novel antimicrobial(s) from these unusual sources which will have huge clinical impact worldwide.

Which Plants Used in Ethnomedicine Are Characterized? Phylogenetic Patterns in Traditional Use Related to Research Effort

Plants are important resources in healthcare and for producing pharmaceutical drugs. Pharmacological and phytochemical characterization contributes to both the safe use of herbal medicines and the identification of leads for drug development. However, there is no recent assessment of the proportion of plants used in ethnomedicine that are characterized in this way. Further, although it is increasingly apparent that plants used in ethnomedicine belong to preferred phylogenetic lineages, it is not known how this relates to the focusing of research effort. Here we identify species and lineages rich in ethnomedicinal use and develop methods to describe how well they are known pharmacologically and/or phytochemically. We find 50% of plant species of the family Leguminosae used in ethnomedicine in Brazil, a geographical area where plants are an important part of healthcare, have been the focus of either phytochemical screening or testing for biological activity. Plant species which have more use reports are studied significantly more often (p < 0.05). Considering the taxonomic distribution of use, 70% of genera that include species with ethnomedicinal use have been studied, compared to 19% of genera with no reported use. Using a novel phylogenetic framework, we show that lineages with significantly greater numbers of ethnomedicinal species are phylogenetically over-dispersed within the family, highlighting the diversity of species used. "Hotnode clades" contain 16% of species but 46% of ethnomedicinally-used species. The ethnomedicinal species in hotnode clades have more use reports per species (p < 0.05), suggesting they are more frequently used. They are also more likely to be characterized pharmacologically and/or phytochemically. Research focus has followed traditional use by these measures, at least for these Brazilian plants, yet ethnomedicinal species yielding candidate drugs, raising public health concerns and more intensively studied lie outside of the hotnode clades.

IMPPAT: A curated database of Indian Medicinal Plants, Phytochemistry And Therapeutics

Phytochemicals of medicinal plants encompass a diverse chemical space for drug discovery. India is rich with a flora of indigenous medicinal plants that have been used for centuries in traditional Indian medicine to treat human maladies. A comprehensive online database on the phytochemistry of Indian medicinal plants will enable computational approaches towards natural product based drug discovery. In this direction, we present, IMPPAT, a manually curated database of 1742 Indian Medicinal Plants, 9596 Phytochemicals, And 1124 Therapeutic uses spanning 27074 plant-phytochemical associations and 11514 plant-therapeutic associations. Notably, the curation effort led to a non-redundant in silico library of 9596 phytochemicals with standard chemical identifiers and structure information. Using cheminformatic approaches, we have computed the physicochemical, ADMET (absorption, distribution, metabolism, excretion, toxicity) and drug-likeliness properties of the IMPPAT phytochemicals. We show that the stereochemical complexity and shape complexity of IMPPAT phytochemicals differ from libraries of commercial compounds or diversity-oriented synthesis compounds while being similar to other libraries of natural products. Within IMPPAT, we have filtered a subset of 960 potential druggable phytochemicals, of which majority have no significant similarity to existing FDA approved drugs, and thus, rendering them as good candidates for prospective drugs. IMPPAT database is openly accessible at: https://cb.imsc.res.in/imppat.

Wahab H. Antituberculosis activity, phytochemical identification of Costus speciosus (J. Koenig) Sm., Cymbopogon citratus (DC. Ex Nees) Stapf., and Tabernaemontana coronaria (L.) Willd. and their effects on the growth kinetics and cellular integrity of Mycobacterium tuberculosis H37Rv

Background

Costus speciosus, Cymbopogon citratus, and Tabernaemontana coronaria are herbal plants traditionally used as remedies for symptoms of tuberculosis (TB) including cough. The aims of the present study were to evaluate the in vitro anti-TB activity of different solvent partitions of these plants, to identify the phytochemical compounds, and to assess the effects of the most active partitions on the growth kinetics and cellular integrity of the tubercle organism.

Methods

The in vitro anti-TB activity of different solvent partitions of the plant materials was determined against M. tuberculosis H37Rv using a tetrazolium colorimetric microdilution assay. The phytochemical compounds in the most active partition of each plant were identified using gas chromatography-mass spectrometry (GC-MS) analysis. The effects of these partitions on the growth kinetics of the mycobacteria were evaluated over 7-day treatment period in a batch culture system. Their effects on the mycobacterial cellular integrity were observed under a scanning electron microscope (SEM).

Results

The respective n-hexane partition of C. speciosus, C. citratus, and T. coronaria exhibited the highest anti-TB activity with minimum inhibitory concentrations (MICs) of 100–200 μg/mL and minimum bactericidal concentration (MBC) of 200 μg/mL. GC-MS phytochemical analysis of these active partitions revealed that majority of the identified compounds belonged to lipophilic fatty acid groups. The active partitions of C. speciosus and T. coronaria exhibited high cidal activity in relation to time, killing more than 99% of the cell population. SEM observations showed that these active plant partitions caused multiple structural changes indicating massive cellular damages.

Conclusions

The n-hexane partition of the plant materials exhibited promising in vitro anti-TB activity against M. tuberculosis H37Rv. Their anti-TB activity was supported by their destructive effects on the integrity of the mycobacterial cellular structure.

Hydromethanolic extract of Rehum emodi exhibits significant antimicrobial activity against acute gastroenteriti bacterial strains

Rehum emodi is an important medicinal herbal and has been reported to exhibit tremendous pharmacological potential. The present study was designed to evaluate the antibacterial activity of hydromethanolic extract of rhizome of Rehum emodi against the acute gastroenteriti bacterial strains. The antimicrobial activity was determined by micro-dilution method. Antioxidant activity was determined by DPPH assay and cytotoxicity by MTT assay. Phytochemical analysis was carried out by LC/MS analysis. The results of the present study showed that hydromethanolic extract of rhizome of Rehum emodi (REE) exhibited significant antimicrobial activity against the gastroenteriti bacterial strains. The MIC values ranged from 25 μg/ml to 125 μg/ml. Moreover, the cytotoxicity of the REE was evaluated against the human breast cell line FR-2 and it was observed that REE exerted minimal cytotoxic effects on these cells with an IC₅₀ of 250 μg/ml indicating that this extract is non-toxic to human cells. The phytochemical analysis revealed the presence of several secondery metabolites such as anthroquinones (anthrone, emodin, aloe emodin and rhein) flavonoids (quercetin, and naringenin) and phenolics (sinapinic acid and gallic acid) which could potentially be responsible for the activity of the extract. In conclusion REE could potentially prove to be useful in the treatment of acute gastroenteritis.

Endophytic bacteria: a new source of bioactive compounds

In recent years, bioactive compounds are in high demand in the pharmaceuticals and naturopathy, due to their health benefits to human and plants. Microorganisms synthesize these compounds and some enzymes either alone or in association with plants. Microbes residing inside the plant tissues, known as endophytes, also produce an array of these compounds. Endophytic actinomycetes act as a promising resource of biotechnologically valuable bioactive compounds and secondary metabolites. Endophytic Streptomyces sp. produced some novel antibiotics which are effective against multi-drug-resistant bacteria Antimicrobial agents produced by endophytes are eco-friendly, toxic to pathogens and do not harm the human. Endophytic inoculation of the plants modulates the synthesis of bioactive compounds with high pharmaceutical properties besides promoting growth of the plants. Hydrolases, the extracellular enzymes, produced by endophytic bacteria, help the plants to establish systemic resistance against pathogens invasion. Phytohormones produced by endophytes play an essential role in plant development and drought resistance management. The high diversity of endophytes and their adaptation to various environmental stresses seem to be an untapped source of new secondary metabolites. The present review summarizes the role of endophytic bacteria in synthesis and modulation of bioactive compounds.