Bioactive constituents from the stems of Dalbergia parviflora

Exploring the Therapeutic Potential of Traditional Antimalarial and Antidengue Plants: A Mechanistic Perspective

Malaria, a highly perilous infectious disease, impacted approximately 230 million individuals globally in 2019. Mosquitoes, vectors of over 10% of worldwide diseases, pose a significant public health menace. The pressing need for novel antimalarial drugs arises due to the imminent threat faced by nearly 40% of the global population and the escalating resistance of parasites to current treatments. This study comprehensively addresses prevalent parasitic and viral illnesses transmitted by mosquitoes, leading to the annual symptomatic infections of 400 million individuals, placing 100 million at constant risk of contracting these diseases. Extensive investigations underscore the pivotal role of traditional plants as rich sources for pioneering pharmaceuticals. The latter half of this century witnessed the ascent of bioactive compounds within traditional medicine, laying the foundation for modern therapeutic breakthroughs. Herbal medicine, notably influential in underdeveloped or developing nations, remains an essential healthcare resource. Traditional Indian medical systems such as Ayurveda, Siddha, and Unani, with a history of successful outcomes, highlight the potential of these methodologies. Current scrutiny of Indian medicinal herbs reveals their promise as cutting-edge drug reservoirs. The propensity of plant-derived compounds to interact with biological receptors positions them as prime candidates for drug development. Yet, a comprehensive perspective is crucial. While this study underscores the promise of plant-based compounds as therapeutic agents against malaria and dengue fever, acknowledging the intricate complexities of drug development and the challenges therein are imperative. The journey from traditional remedies to contemporary medical applications is multifaceted and warrants prudent consideration. This research aspires to offer invaluable insights into the management of malaria and dengue fever. By unveiling plant-based compounds with potential antimalarial and antiviral properties, this study aims to contribute to disease control. In pursuit of this goal, a thorough understanding of the mechanistic foundations of traditional antimalarial and antidengue plants opens doors to novel therapeutic avenues.

Isoflavonoid and Furanochromone Natural Products as Potential DNA Gyrase Inhibitors: Computational, Spectral, and Antimycobacterial Studies

In pursuit of new antitubercular agents, we here report the antimycobacterial (H₃₇Rv) and DNA gyrase inhibitory potential of daidzein and khellin natural products (NPs). We procured a total of 16 NPs based on their pharmacophoric similarities with known antimycobacterial compounds. The H₃₇Rv strain of M. tuberculosis was found to be susceptible to only two out of the 16 NPs procured; specifically, daidzein and khellin each exhibited an MIC of 25 μg/mL. Moreover, daidzein and khellin inhibited the DNA gyrase enzyme with IC₅₀ values of 0.042 and 0.822 μg/mL, respectively, compared to ciprofloxacin with an IC₅₀ value of 0.018 μg/mL. Daidzein and khellin were found to have lower toxicity toward the vero cell line, with IC₅₀ values of 160.81 and 300.23 μg/mL, respectively. Further, molecular docking study and MD simulation of daidzein indicated that it remained stable inside the cavity of DNA GyrB domain for 100 ns.

Current advances on the therapeutic potential of pinocembrin: An updated review

Pinocembrin (5,7-dihydroxyflavone) is a major flavonoid found in many plants, fungi and hive products, mainly honey and propolis. Several in vitro and preclinical studies revealed numerous pharmacological activities of pinocembrin including antioxidant, anti-inflammatory, antimicrobial, neuroprotective, cardioprotective and anticancer activities. Here, we comprehensively review and critically analyze the studies carried out on pinocembrin. We also discuss its potential mechanisms of action, bioavailability, toxicity, and clinical investigations. The wide therapeutic window of pinocembrin makes it a promising drug candidate for many clinical applications. We recommend some future perspectives to improve its pharmacokinetic and pharmacodynamic properties for better delivery that may also lead to new therapeutic advances.

Promising Antimycobacterial Activities of Flavonoids against Mycobacterium sp. Drug Targets: A Comprehensive Review

Tuberculosis (TB) caused by the bacterial pathogen Mycobacterium tuberculosis (Mtb) remains a threat to mankind, with over a billion of deaths in the last two centuries. Recent advancements in science have contributed to an understanding of Mtb pathogenesis and developed effective control tools, including effective drugs to control the global pandemic. However, the emergence of drug resistant Mtb strains has seriously affected the TB eradication program around the world. There is, therefore, an urgent need to develop new drugs for TB treatment, which has grown researchers’ interest in small molecule-based drug designing and development. The small molecules-based treatments hold significant potential to overcome drug resistance and even provide opportunities for multimodal therapy. In this context, various natural and synthetic flavonoids were reported for the effective treatment of TB. In this review, we have summarized the recent advancement in the understanding of Mtb pathogenesis and the importance of both natural and synthetic flavonoids against Mtb infection studied using in vitro and in silico methods. We have also included flavonoids that are able to inhibit the growth of non-tubercular mycobacterial organisms. Hence, understanding the therapeutic properties of flavonoids can be useful for the future treatment of TB.

Structural modification of olibergin A, an isoflavonoid, from Dalbergia stipulacea Roxb. and its cytotoxicity

Fifteen derivatives were synthesized from olibergin A, a major isoflavonoid isolated from the stems of Dalbergia stipulacea Roxb. All compounds were evaluated for cytotoxicity against HCT-116, HT-29, MCF-7 and vero cell lines using MTT assay. Cytotoxicity results showed 5-hydroxy-7,2',4',5'-tetramethoxyisoflavone (5) was the most active with IC₅₀ values of 19.03 ± 0.70, 10.83 ± 1.65, 12.53 ± 0.70 and 13.53 ± 0.84 μM against HCT-116, HT-29, MCF-7 and vero cell lines, respectively. It should be noted that 5-hydroxy-7,2',4',5'-tetramethoxyisoflavone (5) showed two times less toxicity against vero cells than the cisplatin standard (IC₅₀ = 6.55 ± 0.81 μM) while 5 and cisplatin exhibited nearly equal cytotoxicity against the MCF-7 cell line. 5,7,2',4',5'-Pentamethoxyisoflavanone (10) showed an IC₅₀ value of 30.34 ± 1.15 μM against the HCT-116 cell line and exhibited weak cytotoxicity against normal cells, the vero cell line. In addition, 5,7,4'-trihydroxy-2',5'-dimethoxyisoflavan oxime (13) demonstrated cytotoxicity against HT-29 cells with an IC₅₀ value of 31.41 ± 1.38 μM and displayed weak activity toward the vero cell line. The information revealed that these compounds were suitable for development to anticancer agents against HCT-116, HT-29 and MCF-7 cell lines.

A rare isoflavone-quinone and a new flavanone from the roots of Dalbergia stipulacea Roxb

Two previously undescribed compounds, namely dalpulapans F and G (1 and 2), along with 11 known compounds were isolated from the MeOH crude extract of the roots of Dalbergia stipulacea. Dalpulapan F was found as a rare isoflavone-quinone derivative. Their structures and absolute configurations were supported by extensive spectroscopic data analysis, including 1 D and 2 D NMR, HRESIMS data, specific rotation data, and comparison of the experimental and calculated ECD data. Cytotoxicity evaluation of the isolated compounds against HepG2 and KKU-M156 cell lines revealed that isoflavonoid 9 and rotenoid 13 exhibited the most activity against the two cell lines.

Exploring natural compounds for the management of non-small cell lung cancer

A growing incidence of drug resistance and tumour proliferation in non-small cell lung cancer escalates the urge for potential lead molecules. The plant-derived natural compounds have played a pivotal role in potential therapeutic agents owing to its versatility and low toxicity over the past decades. In this study, we have executed an in-silico based screening of 1574 natural compounds against the β-catenin via an integrated pharmacophore approach. Further investigation revealed that Mucronulatol and 7,4'-dihydroxyhomoisoflavanone possess a higher Glide score (-4.748 and -3.943 kcal/mol), binding affinity (-44.763 and -41.883 kcal/mol) alongside drug-likeness property than the iCRT5. Moreover, these compounds are reported to have cytotoxicity against lung cancer cell lines with an IC₅₀ value of 6.74 µM and 8.99 µM respectively. Furthermore, dynamic studies were employed to determine the structural stability and we hope that the lead molecules proposed in this study could effectively inhibit the β-catenin pathway associated with NSCLC.

Two New Carboxyethylflavanones from the Heartwood of Dalbergia tonkinensis and Their Antimicrobial Activities

Two new carboxyethylflavanone derivatives, (2 S)-8-carboxyethylnarigenin (2) and (2 S)-6,8-dicarboxyethylpinocembrin (3) were isolated from the heartwood of Dalbergia tonkinensis Prain, along with four known compounds 1, and 4-6. The chemical structures of two new compounds 2 and 3 were elucidated based on analyses of the spectroscopic data, including 1D and 2D NMR, HR-ESI-MS, IR, UV, and CD spectroscopies. By carrying out antimicrobial assay, CH3OH and CHCl3 fractions exhibited weak MIC value at 200 μg/mL against filamentous fungus A. niger (439), whereas the known flavanone 1 and the new carboxyethylflavanone 2 had MIC at 100 μg/mL.

Southeast Asian Medicinal Plants as a Potential Source of Antituberculosis Agent

Despite all of the control strategies, tuberculosis (TB) is still a major cause of death globally and one-third of the world's population is infected with TB. The drugs used for TB treatment have drawbacks of causing adverse side effects and emergence of resistance strains. Plant-derived medicines have since been used in traditional medical system for the treatment of numerous ailments worldwide. There were nine major review publications on antimycobacteria from plants in the last 17 years. However, none is focused on Southeast Asian medicinal plants. Hence, this review is aimed at highlighting the medicinal plants of Southeast Asian origin evaluated for anti-TB. This review is based on literatures published in various electronic database. A total of 132 plants species representing 45 families and 107 genera were reviewed; 27 species representing 20.5% exhibited most significant in vitro anti-TB activity (crude extracts and/or bioactive compounds 0–<10 µg/ml). The findings may motivate various scientists to undertake the project that may result in the development of crude extract that will be consumed as complementary or alternative TB drug or as potential bioactive compounds for the development of novel anti-TB drug.

Syntheses and Anti-inflammatory Activity of Natural 1,3-Diarylpropenes

First syntheses of five natural 1,3-diarylpropenes (cinnamylphenols) 2-4, 7, and 8 along with synthesis of two other natural 1,3-diarylpropenes 1 and 5 and E-isomer of mucronulastyrene (6) were achieved by Friedel-Crafts alkylation as a key step. Subsequently, their anti-inflammatory effects were also investigated in lipopolysaccharide (LPS)-induced RAW264.7 macrophages. The compounds exhibited significant inhibition of inflammatory mediated nitric oxide (NO) production with no cytotoxicity except compound 8 (dalberatin B) at 10 µM concentration and IC50 values were found in the range from 4.05 to 16.76 µM.

Pseudomonas aeruginosa Biofilm Formation and Persistence, along with the Production of Quorum Sensing-Dependent Virulence Factors, Are Disrupted by a Triterpenoid Coumarate Ester Isolated from Dalbergia trichocarpa, a Tropical Legume

Recently, extracts of Dalbergia trichocarpa bark have been shown to disrupt P. aeruginosa PAO1 quorum sensing (QS) mechanisms, which are key regulators of virulence factor expression and implicated in biofilm formation. One of the active compounds has been isolated and identified as oleanolic aldehyde coumarate (OALC), a novel bioactive compound that inhibits the formation of P. aeruginosa PAO1 biofilm and its maintenance as well as the expression of the las and rhl QS systems. Consequently, the production of QS-controlled virulence factors including, rhamnolipids, pyocyanin, elastase and extracellular polysaccharides as well as twitching and swarming motilities is reduced. Native acylhomoserine lactones (AHLs) production is inhibited by OALC but exogenous supply of AHLs does not restore the production of virulence factors by OALC-treated cultures, indicating that OALC exerts its effect beyond AHLs synthesis in the QS pathways. Further experiments provided a significant inhibition of the global virulence factor activator gacA by OALC. OALC disorganizes established biofilm structure and improves the bactericidal activity of tobramycin against biofilm-encapsulated PAO1 cells. Finally, a significant reduction of Caenorhabditis elegans paralysis was recorded when the worms were infected with OALC-pre-treated P. aeruginosa. Taken together, these results show that triterpenoid coumarate esters are suitable chemical backbones to target P. aeruginosa virulence mechanisms.

New flavanones from the leaves of Cryptocarya chinensis and their antituberculosis activity

Four new flavanones, cryptoflavanones A-D (1-4, resp.), together with eight known compounds, were isolated from the leaves of Cryptocarya chinensis. The structures of these new compounds were determined by spectral analyses. Among the isolated compounds, pinocembrin (5) and cryptocaryone (6) exhibited antituberculosis activity against Mycobacterium tuberculosis H(37) Rv strain in vitro with MIC values of 3.5 and 25.0 μg/ml, respectively.

A New Isoflavone Glycoside from Dalbergia vacciniifolia (Fabaceae)

5,5′-Dihydroxy-2′,4′-dimethoxy-7-[(6-O-β-d-apiofuranosyl-β-d-glucopyranosyl)-oxy]isoflavone (1) was isolated as the major constituent of Dalbergia vacciniifolia root bark ethanol extract together with the four known compounds 5,7-dihydroxy-2′,4′,5′-trimethoxyisoflavone (3), 5,7-dihydroxy-2′,4′-dimethoxy-isoflavone (4), 5-hydroxy-2′,4′,7-trimethoxyisoflavone (5) and 7-hydroxy-2′,4′,5′-trimethoxyisoflavone (6). Identification of compounds was achieved through extensive analysis of 1D and 2D NMR and MS spectroscopy.

Antiplasmodial Natural Products

Malaria is a human infectious disease that is caused by four species of Plasmodium. It is responsible for more than 1 million deaths per year. Natural products contain a great variety of chemical structures and have been screened for antiplasmodial activity as potential sources of new antimalarial drugs. This review highlights studies on natural products with antimalarial and antiplasmodial activity reported in the literature from January 2009 to November 2010. A total of 360 antiplasmodial natural products comprised of terpenes, including iridoids, sesquiterpenes, diterpenes, terpenoid benzoquinones, steroids, quassinoids, limonoids, curcubitacins, and lanostanes; flavonoids; alkaloids; peptides; phenylalkanoids; xanthones; naphthopyrones; polyketides, including halenaquinones, peroxides, polyacetylenes, and resorcylic acids; depsidones; benzophenones; macrolides; and miscellaneous compounds, including halogenated compounds and chromenes are listed in this review.