Natural Products Research Articles

The Yin and Yang of the Natural Product Triptolide and Its Interactions with XPB, an Essential Protein for Gene Expression and DNA Repair

Triptolide, a bioactive diterpene tri-epoxide extracted from Tripterygium wilfordii Hook F (TWHF), exhibits notable pharmacological activities, including anti-inflammatory, immunosuppressive, antifertility, and anticancer effects. Despite its promising therapeutic potential, clinical applications of triptolide are significantly limited by its poor water solubility and substantial toxicity, particularly hepatotoxicity, nephrotoxicity, and cardiotoxicity. These toxic effects are difficult to separate from many of its desired therapeutic effects, the Yin and Yang of triptolide applications. Triptolide’s therapeutic and toxic effects are linked to its inhibitory interactions with XPB, a DNA helicase essential for transcription by RNA polymerase II (RNAPII) and nucleotide excision repair (NER). By irreversibly binding to XPB, triptolide inhibits its ATPase activity, leading to global repression of transcription and impaired NER, which underlies its cytotoxic and antitumor properties. Recent developments, including triptolide prodrugs such as Minnelide and derivatives like glutriptolides, aim to enhance its pharmacokinetic properties and reduce toxicity. This review critically examines triptolide’s chemical structure, therapeutic applications, toxicological profile, and molecular interactions with XPB and other protein targets to inform future strategies that maximize therapeutic efficacy while minimizing adverse effects.

Semisynthetic Studies Establish a Role for Conjugate Halide Exchange in the Formation of Chlorinated Pyrroloiminoquinones and Related Alkaloids.

Two novel pyrroloiminoquinone alkaloids, 6-chlorodamirone A and 6-bromodamirone A, have been identified for the first time from the marine sponge Latrunculia sp. (order: Poecilosclerida: family Latrunculiidae), sourced from Western Australia. Alongside these new compounds, seven previously known metabolites were also isolated. Despite being obtained in submilligram quantities, the structures of these natural products were successfully elucidated using high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. To confirm the structures of these newly discovered alkaloids, a semisynthetic approach was employed starting from the more abundant metabolite, damirone A, additionally, single crystal X-ray crystallography was used to validate our structural proposals. The semisynthetic studies suggest that the chlorinated alkaloids are likely formed through a nonenzymatic conjugate halide substitution reaction rather than an enzymatic process. This reactivity parallels that observed in related metabolites, such as the caulibugulones B and C. Furthermore, a biomimetic cascade reaction was attempted to synthesize the spirodienone moiety characteristic of the discorhabdin alkaloids, inspired by the nucleophilic substitution observed in the tricyclic damirone A system. Albeit unsuccessful, these findings provide valuable insight into the reactivity of halogenated pyrroloiminoquinones under various conditions.

Rezension zu: Lives in Chemistry. Designing Synthetic Methods and Natural Products Synthesis

Rezension zu: Lives in Chemistry. Designing Synthetic Methods and Natural Products Synthesis

200 Years of The Haloform Reaction: Methods and Applications.

Discovered in 1822, the haloform reaction is one of the oldest synthetic organic reactions. The haloform reaction enables the synthesis of carboxylic acids, esters or amides from methyl ketones. The reaction proceeds via exhaustive a-halogenation and then substitution by a nucleophile to liberate a haloform. The methyl group therefore behaves as a masked leaving group. The reaction methodology has undergone several important developments in the last 200 years, transitioning from a diagnostic test of methyl ketones to a synthetically useful tool for accessing complex esters and amides. The success of the general approach has been exhibited through the use of the reaction in the synthesis of many different complex molecules in fields ranging from natural product synthesis, pharmaceuticals, agrochemicals, fragrants and flavouring. The reaction has not been extensively reviewed since 1934. Therefore, herein we provide details of the history and mechanism of the haloform reaction, as well as an overview of the developments in the methodology and a survey of examples, particularly in natural product synthesis, in which the haloform reaction has been used.

Biosynthesis of iron-chelating terramides A-C and their role in Aspergillus terreus infection

Fungal natural products from various species often feature hydroxamic acid motifs that have the ability to chelate iron. These compounds have an array of medicinally and ecologically relevant activities. Through genome mining, gene deletion in the host Aspergillus terreus, and heterologous expression experiments, this study has revealed that a nonribosomal peptide synthetase (NRPS) TamA and a specialized cytochrome P450 monooxygenase TamB catalyze the sequential biosynthetic reactions in the formation of terramides A-C, a series of diketopiperazines (DKPs) with hydroxamic acid motifs. Feeding experiments showed that TamB catalyzes an unprecedented di-hydroxylation of the amide nitrogens in the diketopiperazine core. This tailoring reaction led to the formation of two bidentate iron-binding sites per molecule with an unusual iron-binding stoichiometry. The structure of the terramide A-Fe complex was characterized by liquid chromatography-mass spectrometry (LC-MS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and electron paramagnetic resonance spectroscopy (EPR). Antimicrobial assays showed that the iron-binding motifs are crucial for the activity against bacteria and fungi. Murine infection experiments indicated that terramide production is crucial for the virulence of A. terreus and could be a potential antifungal drug target.

Influence of Goji Berry EM Fermentation and Saccharification Products as Cosmetic Raw Materials on Hair Protection

Purpose: Recently, as the number of cases of side effects due to exposure to chemicals has increased, consumers' anxiety about chemicals has deepened, and interest in cosmetics using natural extracts that do not use chemical ingredients has increased. No-chemicals are being created and scientific research using natural extracts is expanding. Accordingly, Goji berry, which is a natural product handed down from the private sector and is rich in various functional ingredients such as carotinoids, choline, and zeatin, and is said to be excellent for antioxidation effects, was fermented and the active ingredients and effectiveness (in vitro) were investigated.
 Method: Goji berry, which has been found to contain large amounts of functional ingredients such as betaine and rutin, is extracted through double fermentation using EM (Effective Microorganisms) and malt to obtain total polyphenol content, flavonoid content, total sugar content, DPPH radical scavenging ability, and SOD. Effectiveness (in vitro) was examined through activity, catalase activity, hydrogen peroxide, and peroxidase verified.
 Results: As a result of the measurement, the sugar content increased when the EM (Effective Microorganisms) fermented product was enzymatically fermented after extracting Goji berry fruit with purified water. The difference depending on the enzyme fermentation temperature was also higher when the enzyme fermented at 60°C compared to immediately after fermentation. The sugar content increased by about two-fold. The total polyphenol and total flavonoid content decreased when the EM (Effective Microorganisms) fermentation product of the sealed pressurized hot water extract was enzymatically fermented at 60°C.
 Conclusion: The extract double-fermented from Goji berry fruit through EM (Effective Microorganisms) fermentation and malt enzyme fermentation has excellent antioxidant ability, suggesting the possibility of using Goji berry fruit and EM (Effective Microorganisms) fermentation as a natural antioxidant. I confirmed that it exists. In particular, it has antioxidant and antibacterial functions, and its feasibility as a natural raw material used in hair products was found.

Aqueous hydrotropes: An efficient and reusable catalyst for the synthesis of 3-carboxy-coumarin motifs at room temperature

The coumarin moiety plays an important role in the large number of natural products possessing different kinds of biological diversity. Coumarin carboxylic acids show a wide range of biological activities in the pharmaceutical and agricultural fields. Knoevenagel condensation is one of the important reaction pathways for synthesizing coumarin derivatives, and many methodologies have been developed to synthesize this class of compounds. A more environmentally friendly method of synthesizing 3-carboxy coumarins has been successfully carried out using 50% aqueous NaPTS hydrotropes at room temperature, along with various substituted 2-hydroxy benzaldehydes and Meldrum’s acid. This process involves Knoevenagel condensation followed by intramolecular cyclization, providing better product yields (78-95%).

Dual anti-inflammatory effects of curcumin and berberine on acetaminophen-induced liver injury in mice by inhibiting NF-κB activation via PI3K/AKT and PPARγ signaling pathways

Acetaminophen (APAP) overdose is still a leading cause of drug-induced liver injury (DILI), accompanied with severe inflammatory response. However, the therapy for APAP-induced DILI is rather limited. The combined application of natural products to treat DILI induced by APAP may be a new direction of the research. This study was conducted to evaluate the dual anti-inflammatory activity of curcumin (CUR) combined with berberine (BBR) against APAP-mediated DILI. Network pharmacology found that PI3K-Akt and PPAR signaling pathways were primarily involved in anti-DILI of the combination of CUR and BBR. APAP injection enhanced the levels of ALT, AST, IL-1β, IL-6, and TNF-α in mice, while such phenomenon was significantly reversed by the cotreatment of CUR and BBR, which was more effective than either single treatment. The increase of p-NF-κB and p-IKKα/β protein expression and the decrease of p-PI3K, p-AKT, and PPARγ protein expression in APAP-treated mice were markedly inhibited by the coadministration of CUR and BBR. Molecular docking further demonstrated that both CUR and BBR could stably bind to PI3K, AKT, and PPARγ protein. In conclusion, the combination of CUR and BBR more effectively protected liver from APAP-triggered DILI than individual treatment. The mechanism is to alleviate hepatic inflammation by inhibiting NF-κB activation, which is possibly mediated by PI3K/Akt and PPARγ signaling pathways.

β-Selective 2-Deoxy- and 2,6-Dideoxyglucosylations Catalyzed by Bis-Thioureas.

We present methods for β-selective 2-deoxy- and 2,6-dideoxyglucosylations of natural products, carbohydrates, and amino acids using bis-thiourea hydrogen-bond-donor catalysts. Disarming ester protecting groups were necessary to counter the high reactivity of 2-deoxyglycosyl electrophiles toward non-stereospecific SN1 pathways. Alcohol and phenol nucleophiles with both base- and acid-sensitive functionalities were compatible with the catalytic protocol, enabling access to a wide array of 2-deoxy-β-O-glucosides.

Rapid screening of xanthine oxidase inhibitors from Ligusticum wallichii by using xanthine oxidase functionalized magnetic metal-organic framework.

In this study, xanthine oxidase was immobilized for the first time using a novel magnetic metal-organic framework material (Fe3O4-SiO2-NH2@MnO2@ZIF-8-NH2). A ligand fishing method was established to rapidly screen XOD inhibitors from Ligusticum wallichii based on the immobilized XOD. Characterization and properties of the immobilized enzyme revealed its excellent stability and reusability. A ligand was screened from Ligusticum wallichii and identified as ligustilide by ultra-high performance liquid chromatography tandem mass spectrometry. The IC50 value of ligustilide was determined to be 27.70 ± 0.13μM through in vitro inhibition testing. Furthermore, molecular docking verified that ligustilide could bind to amino acid residues at the active site of XOD. This study provides a rapid and effective method for thepreliminary screening of XOD inhibitors from complex natural products and has great potential for further discovery of anti-hyperuricemic compounds.

Plant-Derived Alkaloids as a Potential Source of Treatment for Colorectal Cancer over the Past Five Years: A Comprehensive Review

The gastrointestinal cancer known as colorectal cancer (CRC) is caused by a variety of genetic and epigenetic alterations in the intestinal epithelium of the colon and rectum. It is becoming more common every year. In view of this significant progress, it is urgent and imperative for researchers to work more in this direction in order to improve this health situation that is a major concern for society. Certain phenomena, such as the development of resistance by certain cells as well as the failure of certain therapies, play a part in the significantly changed situation. However, plants have always been used for their therapeutic virtues due to the large number of compounds they contain. Among them, alkaloids (more than 20,000 alkaloids have been isolated from plants, of which about 600 are known to be bioactive), which are one of the most diverse and extensively investigated classes of compounds among natural products, can be consider as a promising approach with regard to their numerous biological activities in general and, in particular their activities against colorectal cancer. This work aims to undertake deeper research on the examination of alkaloids that can be used as lead compounds in the treatment of colorectal cancer. The databases used during the literature searches were Web of Science, PubMed/Medline, and Scopus. This methodology allowed us to obtain 11 studies and 24 alkaloids (axidimins A–D, tabersonine, 19R-hydroxytabersonine, 11-hydroxytabersonine, 11-methoxytabersonine, vandrikidine, fusiformine A, 3-oxotabersonine, 3-oxo-11-methoxytabersonine, melodinine W2, venalstonidine, scandine, (–)-larutienine A, solasonin, berbamine dihydrochloride, nitidine chloride, GB7 acetate, berberine, boldine, Worenine, and chaetocochin J). Axidimin C and axidimin D showed significant cytotoxic effects on CRC (HCT116 cells) with IC50 values of 5.3 and 3.9 μM, respectively, and they were more active than 5-fluorouracil and etoposide (IC50 = 6.4 and 10.6 μM, respectively) taken as references. These two compounds induced G2/M phase arrest in HCT116 cells by downregulating cyclin B1 and cdc2 expression. Subsequently, promoting apoptosis via modulation of Bax and Bcl-2 levels, they enhanced p38 MAPK expression, leading to G2/M cell cycle arrest and apoptosis in HCT116 cells. Chaetocochin J possess significant activity against three different CRC cell lines [RKO (0.5 μM < IC50 = 0.56 μM < 1.0 μM), HCT116 (0.5 μM < IC50 = 0.61 μM < 1.0 μM) and SW480 (0.5 μM < IC50 = 0.65 μM < 1.0 μM)]. The 21 remaining compounds have a moderate anti-colorectal cancer activity. Thus, we believe that axidimin C, axidimin D and chaetocochin J could be promising compounds to fight colorectal cancer cell carcinoma. Nevertheless, future analysis should be performed on the study of the toxicologies of axidimin C and axidimin D.

Pterostilbene Induces Pyroptosis in Breast Cancer Cells through Pyruvate Kinase 2/Caspase-8/Gasdermin C Signaling Pathway

The incidence and mortality of breast cancer increase year by year, and it is urgent to find high-efficiency and low-toxicity anti-cancer drugs. Pterostilbene (PTE) is a natural product with antitumor activity, but the specific antitumor mechanism is not very clear. Aerobic glycolysis is the main energy supply for cancer cells. Pyroptosis is an inflammatory, programmed cell death. The aim of this study was to investigate the effect of PTE on glycolysis and pyroptosis in EMT6 and 4T1 cells and the specific mechanism, and to elucidate the role of pyruvate kinase 2 (PKM2), a key enzyme in glycolysis, in the antitumor role of PTE. Our study suggested that PTE induced pyroptosis by inhibiting tumor glycolysis. PKM2 played an important role in both the inhibition of glycolysis and the induction of pyroptosis by PTE.

Polyphosphoric Acid-Promoted Efficient Synthesis of Cinnamides via Aldol Condensation of Amide

Cinnamides are common core structures that exist in a great number of pharmaceuticals and natural products. The development of efficient methods for preparing cinnamides is in great need. We report herein an efficient polyphosphoric acid (PPA)-promoted direct aldol condensation of an amide for the convenient and straightforward preparation of cinnamides. A variety of cinnamides were obtained in moderate-to-excellent yields (65–89%). This strategy features the use of equivalent amides and a short reaction time.

Chemical Markers in Italian Propolis: Chrysin, Galangin and CAPE as Indicators of Geographic Origin

Knowledge of the chemical composition of propolis is crucial for understanding the characteristics of products of different origins, but also for quality control and regulatory purposes. To date, official monographs or official analyses that allow researchers to evaluate propolis in a proper way have not yet been released. This study focuses on the characterization of twenty-seven Italian propolis samples and the identification of chemical markers that define its geographical provenance. Total polyphenol (TP) and total flavonoid (TF) content, alongside the quantification of pinocembrin, chrysin, galangin, and caffeic acid phenethyl ester (CAPE), were identified as potential markers. Additionally, DPPH assays were conducted to evaluate the antiradical activity of propolis samples. Our findings demonstrated that TPs, TFs and pinocembrin differed in propolis of different origins, especially in samples from the islands. However, the quantification of the sum of chrysin and galangin and CAPE provided a clearer distinction of the geographical origin of the propolis samples. In contrast, the DPPH assay did not prove useful for this purpose, as most results were similar and, therefore, not significant. This study lays the groundwork for future research on propolis. These findings could contribute to the development of more refined methods for distinguishing propolis origins, enhancing the understanding, valuation and quality control of this natural product in various applications.

Network Analysis of Gut Microbial Communities Reveals Key Reason for Quercetin Protects against Colitis

As one of the most representative natural products among flavonoids, quercetin (QUE) has been reported to exhibit beneficial effects on gut health in recent years. In this study, we utilized a dextran sulfate sodium (DSS)-induced colitis mice model to explore the protective effects and underlying mechanisms of QUE on colitis. Our data demonstrated that QUE oral gavage administration significantly ameliorates the symptoms and histopathological changes associated with colitis. Additionally, the concentration of mucin-2, the number of goblet cells, and the expression of tight junction proteins (such as ZO-1, Occludin, and Claudin-1) were all found to be increased. Furthermore, QUE treatment regulated the levels of inflammatory cytokines and macrophage polarization, as well as the oxidative stress-related pathway (Nrf2/HO-1) and associated enzymes. Additionally, 16S rDNA sequencing revealed that QUE treatment rebalances the alterations in colon microbiota composition (inlcuding Bacteroidaceae, Bacteroides, and Odoribacter) in DSS-induced colitis mice. The analysis of network dynamics reveals a significant correlation between gut microbial communities and microenvironmental factors associated with inflammation and oxidative stress, in conjunction with the previously mentioned findings. Collectively, our results suggest that QUE has the potential to treat colitis by maintaining the mucosal barrier, modulating inflammation, and reducing oxidation stress, which may depend on the reversal of gut microbiota dysbiosis.

Cooperative Noncovalent Interactions Controlling Amine-Catalyzed Aldol Reaction Pathways Catalyzed by the Bifunctional Amino Quaternary Phosphonium Ion.

Members of a new class of bifunctional amino quaternary phosphonium salts have been synthesized and utilized as catalysts in aldol condensation reactions, as demonstrated herein. These secondary amines feature a phosphonium ion connected by a carbon chain, enabling the quaternary phosphonium ion to engage in distinct cooperative noncovalent interactions. These interactions work in tandem to stabilize different transition state complexes, exclusively controlling competing amine-catalyzed aldol pathways via the Mannich mechanism. Comprehensive mechanistic investigations were conducted through theoretical calculations. This study uncovers a proximity-driven catalytic mechanism in which the distance between the N and the P+ of the bifunctional catalyst emerges as a critical factor determining catalytic efficacy. The method has been demonstrated through its application to the total synthesis of several bioactive natural products.

Progress in Research on Terpenoid Biosynthesis and Terpene Synthases of Lauraceae Species

Lauraceae, an important family of Angiospermae, comprises over 2500 species widely distributed in tropical and subtropical evergreen broad-leaved forests. This family is renowned for its rich resource of terpenoids, particularly monoterpenes, sesquiterpenes, and diterpenes. These compounds not only impart specific scents to Lauraceae species but also play crucial roles in plant growth, development, and environmental adaptation. These compounds also possess extensive bioactivities, such as antioxidant, antibacterial, anti-inflammatory, and neuroprotective effects, making them valuable in the fields of perfumery, cosmetics, food, and medicine, and thus holding significant economic value. Recent advancements in high-throughput technologies, especially genomics, transcriptomics, and metabolomics, have significantly advanced our knowledge of the chemical constituents and biosynthetic pathways of terpenoids in Lauraceae species. Such progress has also shed light on the diversity and functionality of the terpene synthases (TPSs) gene family, a key enzyme involved in terpenoid biosynthesis. This paper reviews the latest research findings on the biosynthetic pathways of terpenoids and their key enzyme-encoding gene families in Lauraceae plants. We also analyze the evolutionary patterns of TPS gene family members of four Lauraceae species at the whole-genome level and summarize their mechanisms of action in secondary metabolite synthesis. Furthermore, this paper highlights the current research challenges and proposes prospects, such as the complexity of gene families, the uncertainties in functional predictions, and unclear regulatory mechanisms. Our objective is to provide scientific foundations for the in-depth analysis of terpenoid biosynthesis mechanisms and the development and utilization of natural products in Lauraceae plants.

The National Center for Natural Products Research (NCNPR) at 30: A Legacy of Pioneering Research in Natural Products and Dietary Supplements

Since its establishment in 1994, the National Center for Natural Products Research (NCNPR) at the University of Mississippi has made notable contributions to the field of natural product research, coinciding with the passage of the Dietary Supplement Health and Education Act. Over the past three decades, the Center has focused on studying plants, herbs, and other natural materials for applications in medicine, agriculture, and nutraceuticals, particularly in the area of botanical dietary supplements. NCNPR scientists have been actively engaged in developing and improving quality control measures to help ensure the safety of dietary supplements in response to a growing market. The Center’s research efforts have led to its designation as a U.S. Food and Drug Administration Center of Excellence, reflecting its role in advancing scientific understanding of natural products. Through collaborations with various stakeholders and regulators, NCNPR has contributed to shaping the regulatory landscape for botanical dietary supplements, highlighting both their potential health benefits and associated risks, such as product adulteration. The Center’s influence is also evident internationally, as demonstrated by its annual International Conference on the Science of Botanicals, which will mark its 26th year in April 2025. This overview outlines NCNPR’s role in supporting research, regulation, and safety in the natural products field.

Enhancing Antibiotic Efficacy with Natural Compounds: Synergistic Activity of Tannic Acid and Nerol with Commercial Antibiotics against Pathogenic Bacteria

The search for synergies between natural products and commercial antibiotics is a promising strategy against bacterial resistance. This study determined the antimicrobial capacity of Nerol (NE) and Tannic Acid (TA) against 14 pathogenic bacteria, including ESKAPE pathogens. TA exhibited the lowest Minimum Inhibitory Concentrations (MICs) at 162.5 µg/mL against Pasteurella aerogenes and 187.5 µg/mL against Acinetobacter baumannii (WHO priority 1). NE showed its lowest MIC of 500 µg/mL against both Pasteurella aerogenes and Salmonella enterica. A total of 35 combinations of NE and 13 of TA with eight commercial antibiotics were analyzed. For NE, combinations with Streptomycin and Gentamicin were effective against Salmonella enterica, Bacillus subtilis, and Streptococcus agalactiae, with antibiotic MIC reductions between 75.0 and 87.5%. TA showed six synergies with Chloramphenicol, Ampicillin, Erythromycin, and Streptomycin against Acinetobacter baumannii, Streptococcus agalactiae, and Pasteurella aerogenes, with MIC reductions between 75.0 and 93.7%. Additionally, 31 additive effects with antibiotics for NE and 8 for TA were found. Kinetic studies on these synergies showed complete inhibition of bacterial growth, suggesting that natural products enhance antibiotics by facilitating their access to targets or preventing resistance. Given their safety profiles recognized by the EPA and FDA, these natural products could be promising candidates as antibiotic enhancers.

Looking for Actives in the Haystack: Merging HRMS2-Based Molecular Networking, Chemometrics, and 13C NMR-Based Dereplication Approaches.

The identification of bioactive natural products (NPs) in complex mixtures has become an important subject of contemporary NP research. In an attempt to address this challenge, the present work proposes an integrated strategy that combines tandem mass spectrometry (MS2)-based molecular networking (MN), a partial least-squares (PLS) chemometric model, as well as 13C NMR-based dereplication using MixONat software. In addition, an advanced glycation end product (AGEs) assay was used for activity evaluation. The approach was implemented on a Garcinia parvifolia bark extract that comprised a high content of prenylated xanthones and had previously shown a notable inhibitory effect on AGE formation. As a main result, the proposed strategy permitted the identification of potentially active metabolites within complex mixtures and their annotation with a higher level of confidence by NMR data. Overall, this comprehensive approach provides a powerful and efficient solution for the targeting and annotating of active compounds in complex NP mixtures.