The effect of celastrol in combination with 5-fluorouracil on proliferation and apoptosis of gastric cancer cell lines.

Background: Despite the availability of chemotherapy drugs such as 5-fluorouracil (5-FU), the treatment of some cancers such as gastric cancer remains challenging due to drug resistance and side effects. This study aimed to investigate the effect of celastrol in combination with the chemotherapy drug 5-FU on proliferation and induction of apoptosis in human gastric cancer cell lines (AGS and EPG85-257). Materials and Methods: In this in vitro study, AGS and EPG85-257 cells were treated with different concentrations of celastrol, 5-FU, and their combination. Cell proliferation was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The synergistic effect of 5-FU and celastrol was studied using Compusyn software. The DNA content at different phases of the cell cycle and apoptosis rate was measured using flow cytometry. Results: Co-treatment with low concentrations (10% inhibitory concentration (IC10)) of celastrol and 5-FU significantly reduced IC50 (p < 0.05) so that 48 h after treatment, IC50 was calculated at 3.77 and 6.9 µM for celastrol, 20.7 and 11.6 µM for 5-FU, and 5.03 and 4.57 µM for their combination for AGS and EPG85-257 cells, respectively. The mean percentage of apoptosis for AGS cells treated with celastrol, 5-FU, and their combination was obtained 23.9, 41.2, and 61.9, and for EPG85-257 cells 5.65, 46.9, and 55.7, respectively. In addition, the 5-FU and celastrol-5-FU combination induced cell cycle arrest in the synthesis phase. Conclusions: Although celastrol could decrease the concentration of 5-fluorouracil that sufficed to suppress gastric cancer cells, additional studies are required to arrive at conclusive evidence on the anticancer effects of celastrol.

Microbial allies: exploring fungal endophytes for biosynthesis of terpenoid indole alkaloids.

Terpenoid indole alkaloids (TIAs) are natural compounds found in medicinal plants that exhibit various therapeutic activities, such as antimicrobial, anti-inflammatory, antioxidant, anti-diabetic, anti-helminthic, and anti-tumor properties. However, the production of these alkaloids in plants is limited, and there is a high demand for them due to the increasing incidence of cancer cases. To address this research gap, researchers have focused on optimizing culture media, eliciting metabolic pathways, overexpressing genes, and searching for potential sources of TIAs in organisms other than plants. The insufficient number of essential genes and enzymes in the biosynthesis pathway is the reason behind the limited production of TIAs. As the field of natural product discovery from biological species continues to grow, endophytes are being investigated more and more as potential sources of bioactive metabolites with a variety of chemical structures. Endophytes are microorganisms (fungi, bacteria, archaea, and actinomycetes), that exert a significant influence on the metabolic pathways of both the host plants and the endophytic cells. Bio-prospection of fungal endophytes has shown the discovery of novel, high-value bioactive compounds of commercial significance. The discovery of therapeutically significant secondary metabolites has been made easier by endophytic entities' abundant but understudied diversity. It has been observed that fungal endophytes have better intermediate processing ability due to cellular compartmentation. This paper focuses on fungal endophytes and their metabolic ability to produce complex TIAs, recent advancements in this area, and addressing the limitations and future perspectives related to TIA production.

Pharmacokinetic evaluation of ibrexafungerp for the treatment of vulvovaginal candidiasis and beyond.

INTRODUCTION: Ibrexafungerp is a new triterpenoid antifungal agent with activity against a variety of fungal species, including Aspergillus spp. and echinocandin-resistant Candida spp. AREAS COVERED: This evaluation will summarize currently available clinical evidence on the use of ibrexafungerp in the treatment/prevention of vulvovaginal candidiasis (VVC) and detail the mechanism of action, pharmacokinetic/pharmacodynamic parameters, and ongoing/latest research involving ibrexafungerp. EXPERT OPINION: The evidence involving the utilization of ibrexafungerp for the treatment of VVC shows that it is superior when compared to placebo and has comparable clinical cure rates when compared with fluconazole. Ibrexafungerp demonstrates reliable coverage against several Candida spp. including echinocandin-resistant strains, Candida auris, and Aspergillus spp. For VVC, a dose of 300 mg (two 150 mg tablets) twice daily is recommended and does not require dose adjustments based on renal or hepatic function. The use of ibrexafungerp outside of VVC is currently under study with several ongoing trials showing promising interim data.

Light-responsive transcription factors VvHYH and VvGATA24 mediate wax terpenoid biosynthesis in Vitis vinifera.

The cuticular wax that covers the surfaces of plants is the first barrier against environmental stresses and increasingly accumulates with light exposure. However, the molecular basis of light-responsive wax biosynthesis remains elusive. In grape (Vitis vinifera), light exposure resulted in higher wax terpenoid content and lower decay and abscission rates than controls kept in darkness. Assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) and RNA-seq data were integrated to draw the chromatin accessibility and cis-elements regulatory map to identify the potential action sites. Terpenoid synthase 12 (VvTPS12) and 3-Hydroxy-3-methylglutaryl-CoA reductase 2 (VvHMGR2) were identified as grape wax biosynthesis targets, while VvHYH and VvGATA24 were identified as terpenoid biosynthesis activators, as more abundant wax crystals and higher wax terpenoid content were observed in transiently overexpressed grape berries and Nicotiana benthamiana leaves. The interaction between VvHYH and the open chromatin of VvTPS12 was confirmed qualitatively using a dual luciferase assay and quantitatively using surface plasma resonance, with an equilibrium dissociation constant of 2.81 nM identified via the latter approach. Molecular docking simulation implied the structural nature of this interaction, indicating that 24 amino acid residues of VvHYH, including Arg106A, could bind to the VvTPS12 G-box cis-element. VvGATA24 directly bound to the open chromatin of VvHMGR2, with an equilibrium dissociation constant of 8.59 nM. 12 amino acid residues of VvGATA24, including Pro218B, interacted with the VvHMGR2 GATA-box cis-element. Our work characterizes the mechanism underlying light-mediated wax terpenoid biosynthesis and provides gene targets for future molecular breeding.

Chromosome genome assembly of the Camphora longepaniculata (Gamble) with PacBio and Hi-C sequencing data.

Introduction: Camphora longepaniculata, a crucial commercial crop and a fundamental component of traditional Chinese medicine, is renowned for its abundant production of volatile terpenoids. However, the lack of available genomic information has hindered pertinent research efforts in the past. Methods: To bridge this gap, the present study aimed to use PacBio HiFi, short-read, and highthroughput chromosome conformation capture sequencing to construct a chromosome-level assembly of the C. longepaniculata genome. Results and discussion: With twelve chromosomes accounting for 99.82% (766.69 Mb) of the final genome assembly, which covered 768.10 Mb, it was very complete. Remarkably, the assembly's contig and scaffold N50 values are exceptional as well-41.12 and 63.78 Mb, respectively-highlighting its excellent quality and intact structure. Furthermore, a total of 39,173 protein-coding genes were predicted, with 38,766 (98.96%) of them being functionally annotated. The completeness of the genome was confirmed by the Benchmarking Universal Single-Copy Ortholog evaluation, which revealed 99.01% of highly conserved plant genes. As the first comprehensive assembly of the C. longepaniculata genome, it provides a crucial starting point for deciphering the complex pathways involved in terpenoid production. Furthermore, this excellent genome serves as a vital resource for upcoming research on the breeding and genetics of C. longepaniculata.

Aerial signaling by plant-associated Streptomyces setonii WY228 regulates plant growth and enhances salt stress tolerance.

Plant-associated streptomycetes play important roles in plant growth and development. However, knowledge of volatile-mediated crosstalk between Streptomyces spp. and plants remains limited. In this study, we investigated the impact of volatiles from nine endophytic Streptomyces strains on the growth and development of plants. One versatile strain, Streptomyces setonii WY228, was found to significantly promote the growth of Arabidopsis thaliana and tomato seedlings, confer salt tolerance, and induce early flowering and increased fruit yield following volatile treatment. Analysis of plant growth-promoting traits revealed that S. setonii WY228 could produce indole-3-acetic acid, siderophores, ACC deaminase, fix nitrogen, and solubilize inorganic phosphate. These capabilities were further confirmed through genome sequencing and analysis. Volatilome analysis indicated that the volatile organic compounds emitted from ISP-2 medium predominantly comprised sesquiterpenes and 2-ethyl-5-methylpyrazine. Further investigations showed that 2-ethyl-5-methylpyrazine and sesquiterpenoid volatiles were the primary regulators promoting growth, as confirmed by experiments using the terpene synthesis inhibitor phosphomycin, pure compounds, and comparisons of volatile components. Transcriptome analysis, combined with mutant and inhibitor studies, demonstrated that WY228 volatiles promoted root growth by activating Arabidopsis auxin signaling and polar transport, and enhanced root hair development through ethylene signaling activation. Additionally, it was confirmed that volatiles can stimulate plant abscisic acid signaling and activate the MYB75 transcription factor, thereby promoting anthocyanin synthesis and enhancing plant salt stress tolerance. Our findings suggest that aerial signaling-mediated plant growth promotion and abiotic stress tolerance represent potentially overlooked mechanisms of Streptomyces-plant interactions. This study also provides an exciting strategy for the regulation of plant growth and the improvement of horticultural crop yields within sustainable agricultural practices.

Target Identification and Mechanistic Characterization of Indole Terpenoid Mimics: Proper Spindle Microtubule Assembly Is Essential for Cdh1-Mediated Proteolysis of CENP-A.

Centromere protein A (CENP-A), a histone H3 variant specific to centromeres, is crucial for kinetochore positioning and chromosome segregation. However, its regulatory mechanism in human cells remains incompletely understood. A structure-activity relationship (SAR) study of the cell-cycle-arresting indole terpenoid mimic JP18 leads to the discovery of two more potent analogs, (+)-6-Br-JP18 and (+)-6-Cl-JP18. Tubulin is identified as a potential cellular target of these halogenated analogs by using the drug affinity responsive target stability (DARTS) based method. X-ray crystallography analysis reveals that both molecules bind to the colchicine-binding site of ß-tubulin. Treatment of human cells with microtubule-targeting agents (MTAs), including these two compounds, results in CENP-A accumulation by destabilizing Cdh1, a co-activator of the anaphase-promoting complex/cyclosome (APC/C) E3 ubiquitin ligase. This study establishes a link between microtubule dynamics and CENP-A accumulation using small-molecule tools and highlights the role of Cdh1 in CENP-A proteolysis.

Recent progress in the extraction of terpenoids from essential oils and separation of the enantiomers by GC-MS.

Terpenoids possess significant physiological activities and are rich in essential oils. Some terpenoids have chiral centers and could form enantiomers with distinct physiological activities. Therefore, the extraction and separation of terpenoids enantiomers are very important and have attracted extensive attention in recent years. Meanwhile, the specific distribution and enantiomer excess results (the excess of one enantiomer over the other in a mixture of enantiomers) could be used as quality markers for illegitimate adulteration, origin identification, and exploring component variations and functional interrelations across different plant tissues. In this study, an overview of the progress in the extraction of terpenoids from essential oils and the separation of their enantiomers over the past two decades has been made. Extraction methods were retrieved by the resultant network visualization findings. The results showed that the predominant methods are hydrodistillation, solvent-free microwave extraction, headspace solid-phase microextraction and supercritical fluid extraction methods. GC-MS combined with chiral chromatography columns is commonly used for the separation of enantiomers, while 2D GC is found to have stronger resolution ability. Finally, some prospects for future research directions in the extraction and separation identification of essential oils are proposed.

Biosynthesis and Assembly Logic of Fungal Hybrid Terpenoid Natural Products.

In recent decades, fungi have emerged as significant sources of diverse hybrid terpenoid natural products, and their biosynthetic pathways are increasingly unveiled. This review mainly focuses on elucidating the various strategies underlying the biosynthesis and assembly logic of these compounds. These pathways combine terpenoid moieties with diverse building blocks including polyketides, nonribosomal peptides, amino acids, p-hydroxybenzoic acid, saccharides, and adenine, resulting in the formation of plenty of hybrid terpenoid natural products via C-O, C-C, or C-N bond linkages. Subsequent tailoring steps, such as oxidation, cyclization, and rearrangement, further enhance the biological diversity and structural complexity of these hybrid terpenoid natural products. Understanding these biosynthetic mechanisms holds promise for the discovery of novel hybrid terpenoid natural products from fungi, which will promote the development of potential drug candidates in the future.

Rational Design for the Complete Synthesis of Stevioside in Saccharomyces cerevisiae.

Stevioside is a secondary metabolite of diterpenoid glycoside production in plants. It has been used as a natural sweetener in various foods because of its high sweetness and low-calorie content. In this study, we constructed a Saccharomyces cerevisiae strain for the complete synthesis of stevioside using a metabolic engineering strategy. Firstly, the synthesis pathway of steviol was modularly constructed in S. cerevisiae BY4742, and the precursor pathway was strengthened. The yield of steviol was used as an indicator to investigate the expression effect of different sources of diterpene synthases under different combinations, and the strains with further improved steviol yield were screened. Secondly, glycosyltransferases were heterologously expressed in this strain to produce stevioside, the sequence of glycosyltransferase expression was optimized, and the uridine diphosphate-glucose (UDP-Glc) supply was enhanced. Finally, the results showed that the strain SST-302III-ST2 produced 164.89 mg/L of stevioside in a shake flask experiment, and the yield of stevioside reached 1104.49 mg/L in an experiment employing a 10 L bioreactor with batch feeding, which was the highest yield reported. We constructed strains with a high production of stevioside, thus laying the foundation for the production of other classes of steviol glycosides and holding good prospects for application and promotion.

Enzymatic Synthesis of Novel Terpenoid Glycoside Derivatives Decorated with N-Acetylglucosamine Catalyzed by UGT74AC1.

The addition of the O-linked N-acetylglucosamine (O-GlcNAc) is a significant modification for active molecules, such as proteins, carbohydrates, and natural products. However, the synthesis of terpenoid glycoside derivatives decorated with GlcNAc remains a challenging task due to the absence of glycosyltransferases, key enzymes for catalyzing the transfer of GlcNAc to terpenoids. In this study, we demonstrated that the enzyme mutant UGT74AC1T79Y/L48M/R28H/L109I/S15A/M76L/H47R efficiently transferred GlcNAc from uridine diphosphate (UDP)-GlcNAc to a variety of terpenoids. This powerful enzyme was employed to synthesize GlcNAc-decorated derivatives of terpenoids, including mogrol, steviol, andrographolide, protopanaxadiol, glycyrrhetinic acid, ursolic acid, and betulinic acid for the first time. To unravel the mechanism of UDP-GlcNAc recognition, we determined the X-ray crystal structure of the inactivated mutant UGT74AC1His18A/Asp111A in complex with UDP-GlcNAc at a resolution of 1.66 Å. Through molecular dynamic simulation and activity analysis, we revealed the molecular mechanism and catalytically important amino acids directly involved in the recognition of UDP-GlcNAc. Overall, this study not only provided a potent biocatalyst capable of glycodiversifying natural products but also elucidated the structural basis for UDP-GlcNAc recognition by glycosyltransferases.

Engineering Sclareol Production on the Leaf Surface of Nicotiana tabacum.

Sclareol, a diterpene alcohol, is the most common starting material for the synthesis of ambrox, which serves as a sustainable substitute for ambergris, a valuable fragrance secreted by sperm whales. Sclareol has also been proposed to possess antibacterial, antifungal, and anticancer activities. However, in nature, sclareol is only produced by a few plant species, including Cistus creticus, Cleome spinosa, Nicotiana glutinosa, and Salvia sclarea, which limits its commercial application. In this study, we cloned the two genes responsible for sclareol biosynthesis in S. sclarea, labda-13-en-8-ol diphosphate synthase (LPPS) and sclareol synthase (SS), and overexpressed them in tobacco (Nicotiana tabacum L.). The best transgenic tobacco lines accumulated 4.1 µg/cm2 of sclareol, which is comparable to the sclareol production of N. glutinosa, a natural sclareol producer. Thus, sclareol synthesis in tobacco represents a potential alternative means for the production of this high-value compound.

Docking carbocations into terpene synthase active sites using chemically meaningful constraints-The TerDockin approach.

Terpenes are a diverse class of natural products which have long been sought after for their chemical properties as medicine, perfumes, and for food flavoring. Computational docking studies of terpene mechanisms have been a challenge due to the lack of strong directing groups which many docking programs rely on. In this chapter, we dive into our computational method Terdockin (Terpene-Docking) as a successful methodology in modeling terpene synthase mechanisms. This method could also be used as inspiration for any multi-ligand docking project.

Research progress on the types, functions, biosynthesis, and metabolic regulation of ginkgo terpenoids.

Ginkgo biloba L. is a relict plant endemic to China that is commonly considered a "living fossil". It contains unique medicinal compounds that play important roles in its response to various stresses and help maintain human health. Ginkgo terpenoids are known to be important active ingredients but have received less attention than flavonoids. Hence, this review focuses on recent progress in research on the pharmacological effects of ginkgo terpenoid and the bioactivities of different terpenoid monomers. Many key structural genes, enzyme-encoding genes, transcription factors, and noncoding RNAs involved in the ginkgo terpenoid pathway were identified. Finally, many external factors (ecological factors, hormones, etc.) that regulate the biosynthesis and metabolism of terpenoids were proposed. All these findings improve the understanding of the biosynthesis, accumulation, and medicinal functions of terpenoids. Finally, this review includes an in-depth discussion regarding the limitations of terpenoid-related studies and potential future research directions.

Computational Analysis of Albaflavenone Interaction with SlMAPK1 for Drought Resistance in Tomato.

As global agricultural challenges intensify, particularly drought stress, the exploration of innovative strategies for crop resilience has become crucial. This study focuses on the role of the microbial endophyte metabolite Albaflavenone in enhancing drought resistance in tomato (Solanum lycopersicum L.) through the activation of the SlMAPK1 protein in the MAPK pathway. To computationally analyze the interaction between Albaflavenone and SlMAPK1 and to elucidate the potential enhancement of drought tolerance in tomato plants through this interaction. We utilized molecular docking, homology modeling, and molecular dynamics simulations to investigate the binding affinities and interaction dynamics between SlMAPK1 and Albaflavenone. Functional network analysis was employed to examine protein-protein interactions within the MAPK pathway, while the MM-GBSA method was used to calculate binding free energies. Our computational analyses revealed that Albaflavenone exhibited a high binding affinity to SlMAPK1 with a binding energy of - 8.9 kcal/mol. Molecular dynamics simulations showed this interaction significantly stabilized SlMAPK1, suggesting enhanced activity. Specifically, the root mean square deviation (RMSD) of the Albaflavenone-SlMAPK1 complex stabilized at around 3.1 Å, while the root mean square fluctuations (RMSF) indicated consistent amino acid conformations. Additionally, the radius of gyration (Rg) analysis demonstrated minimal variance, suggesting a compact and stable protein-ligand complex. The significant binding affinity between Albaflavenone and SlMAPK1 highlights the potential of leveraging plant-microbe interactions in developing sustainable agricultural practices. These findings also demonstrate the effectiveness of computational methods in dissecting complex biological interactions, contributing to a deeper understanding of plant resilience strategies against environmental stresses.

Synthesis of a Library of Terpenoid Alkaloid-like Compounds Containing Medium-sized Rings via Reconstruction of the Humulene Skeleton.

The construction of a chemical library based on natural products is a promising method for the synthesis of natural product-like compounds. In this study, we synthesized a terpenoid alkaloid-like compound library based on the humulene skeleton. Our strategy, which enables access to diverse ring systems such as 11-membered monocyclic, oxabicyclic, and medium-sized aza ring-containing scaffolds, involves the introduction of a nitrogen atom, an intermolecular C-O bond formation via Lewis acid-mediated epoxide-opening transannulation, and a ring-reconstruction strategy based on olefin metathesis. A cheminformatics analysis based on their structural and physicochemical properties revealed that the synthesized compounds have high three-dimensionality and high natural product likeness scores but with structural novelty. The usefulness of the terpenoid alkaloid-like compound library for drug discovery and the accessibility to structure-activity relationship studies were validated by performing an assay for osteoclast-specific tartrate-resistant acid phosphatase activity, resulting in the identification of a lead compound for bone-resorptive diseases such as osteoporosis.

The role of the Golden2-like (GLK) transcription factor in regulating terpenoid indole alkaloid biosynthesis in Catharanthus roseus.

KEY MESSAGE: A GLK homologue was identified and functionally characterized in Catharanthus roseus. Silencing CrGLK with VIGS or the chloroplast retrograde signaling inducer lincomycin increased terpenoid indole alkaloid biosynthesis. Catharanthus roseus is the sole source of the chemotherapeutic terpenoid indole alkaloids (TIAs) vinblastine and vincristine. TIA pathway genes, particularly genes in the vindoline pathway, are expressed at higher levels in immature versus mature leaves, but the molecular mechanisms responsible for this developmental regulation are unknown. We investigated the role of GOLDEN2-LIKE (GLK) transcription factors in contributing to this ontogenetic regulation since GLKs are active in seedlings upon light exposure and in the leaf's early development, but their activity is repressed as leaves age and senesce. We identified a GLK homologue in C. roseus and functionally characterized its role in regulating TIA biosynthesis, with a focus on the vindoline pathway, by transiently reducing its expression through two separate methods: virus-induced gene silencing (VIGS) and application of chloroplast retrograde signaling inducers, norflurazon and lincomycin. Reducing CrGLK levels with each method reduced chlorophyll accumulation and the expression of the light harvesting complex subunit (LHCB2.2), confirming its functional homology with GLKs in other plant species. In contrast, reducing CrGLK via VIGS or lincomycin increased TIA accumulation and TIA pathway gene expression, suggesting that CrGLK may repress TIA biosynthesis. However, norflurazon had no effect on TIA gene expression, indicating that reducing CrGLK alone is not sufficient to induce TIA biosynthesis. Future work is needed to clarify the specific molecular mechanisms leading to increased TIA biosynthesis with CrGLK silencing. This is the first identification and characterization of GLK in C. roseus and the first investigation of how chloroplast retrograde signaling might regulate TIA biosynthesis.

Evaluation of the cytotoxic activities of the essential oil from Pistacia atlantica Desf. oleoresin on human gastric cancer cell lines.

Numerous herbal products have been the subject of research regarding their potential role in cancer prevention or adjuvant therapy. Pistacia atlantica and its main phytochemicals have garnered significant attention for their potential anti-cancer effects. The study aimed to assess the growth inhibitory effects of P. atlantica essential oil (PAEO) on MKN-45 and AGS cells. This study quantified the volatile compounds in PAEO using Gas Chromatography-Mass Spectrometry (GC-MS). Subsequently, MKN-45 and AGS cells were treated with varying concentrations of PAEO (5%, 2.5%, 1.25%, 0.625%, 0.3125%, 0.156%, 0.0781%, 0.0391%, 0.0195%) for 24 h. Cell viability was evaluated through the MTT assay. The impact of PAEO on gene expression was investigated by quantifying the mRNA levels of Bax and Bcl2 in the various experimental groups using quantitative Real-Time PCR (qRT-PCR) analysis. Additionally, flow cytometry was utilized to evaluate apoptosis in the treated cells. The analysis of PAEO revealed that α-pinene was the predominant monoterpene, constituting 87.9% of the oil composition. The cytotoxic effects of PAEO were evaluated, and it was found that the oil significantly reduced the viability of MKN-45 and AGS cells. The IC50 for MKN-45 cells was determined to be 1.94 × 10-3% after 24 h of treatment, while for AGS cells the IC50 was 2.8 × 10-3% after 24 h. Additionally, the research revealed that PAEO triggered a notable rise in apoptotic cells in both AGS and MKN-45 cell lines. Moreover, at the molecular level, the findings indicated an increase in Bax expression and a decrease in Bcl2 mRNA expression, providing further evidence of the induction of apoptosis in both MKN-45 and AGS cell lines following PAEO treatment. The findings of this study offer evidence supporting the cytotoxic effects of PAEO on gastric cancer cell lines by promoting apoptosis. The findings suggest that PAEO may offer potential as a therapeutic candidate in managing and treating gastric cancer.

Exploring the Biomedical Potential of Terpenoid Alkaloids: Sources, Structures, and Activities.

Terpenoid alkaloids are recognized as a class of compounds with limited numbers but potent biological activities, primarily derived from plants, with a minor proportion originating from animals and microorganisms. These alkaloids are synthesized from the same prenyl unit that forms the terpene skeleton, with the nitrogen atom introduced through ß-aminoethanol, ethylamine, or methylamine, leading to a range of complex and diverse structures. Based on their skeleton type, they can be categorized into monoterpenes, sesquiterpenes, diterpenes, and triterpene alkaloids. To date, 289 natural terpenoid alkaloids, excluding triterpene alkaloids, have been identified in studies published between 2019 and 2024. These compounds demonstrate a spectrum of biological activities, including anti-inflammatory, antitumor, antibacterial, analgesic, and cardioprotective effects, making them promising candidates for further development. This review provides an overview of the sources, chemical structures, and biological activities of natural terpenoid alkaloids, serving as a reference for future research and applications in this area.

Enhancing structural diversity of terpenoids by multisubstrate terpene synthases.

Terpenoids are one of the largest class of natural products with diverse structures and activities. This enormous diversity is embedded in enzymes called terpene synthases (TSs), which generate diverse terpene skeletons via sophisticated cyclization cascades. In addition to the many highly selective TSs, there are many promiscuous TSs that accept multiple prenyl substrates, or even noncanonical ones, with 6, 7, 8, 11, and 16 carbon atoms, synthesized via chemical approaches, C-methyltransferases, or engineered lepidopteran mevalonate pathways. The substrate promiscuity of TSs not only expands the structural diversity of terpenes but also highlights their potential for the discovery of novel terpenoids via combinatorial biosynthesis. In this review, we focus on the current knowledge on multisubstrate terpene synthases (MSTSs) and highlight their potential applications.