Key phytochemicals contributing to the bitterness of quinoa

Despite its nutritional components and potential health benefits, the bitterness of quinoa seed limits its utilization in the food industry. Saponins are believed to be the main cause of the bitterness, but it is still uncertain which specific compound is responsible. This study aimed to isolate the main components contributing to the bitterness in quinoa seed by solvent extraction and various column chromatography techniques guided by sensory evaluation. Five compounds were identified by mass spectrometry and nuclear magnetic resonance analyses, with the dose-over-threshold factors from 29.03 to 198.89. The results confirmed that triterpenoids are responsible for the bitter taste in quinoa seed, with phytolaccagenic acid derivatives being the primary contributor. Additionally, kaempferol 3-O-(2″, 6″-di-O-α-rhamnopyranosyl)-β-galactopyranoside (namely mauritianin), was demonstrated for the first time to be associated with the bitterness of quinoa. This study could provide new insight into the bitter compound identification in quinoa.

Five new secondary metabolites from Aster tataricus

Aster tataricus L.f. is highly valued for its rich reserves of bioactive compounds. Our research focused on the identification of previously unreported compounds found within the ethanol extract of A. tataricus. Through meticulous spectroscopic analyses and computational methods like NMR calculations and ECD, we successfully elucidated the structures of five novel compounds termed tatarisides A-E (1-5), alongside two known compounds (6, 7). The anti-inflammatory assays conducted yielded noteworthy results, particularly in relation to compounds 1 and 5. These compounds exhibited significant potential in inhibiting the release of NO in LPS-induced RAW 264.7 cells, as evidenced by their respective IC50 values of 17.81 ± 1.25 μM and 13.32 ± 0.84 μM. The discovery of these new compounds adds to the existing knowledge of A. tataricus's chemical composition and potential applications.

Unveil the mechanism for EHMT -- A novel triterpenoid inhibits proliferation and induces apoptosis in colon cancer through ROS-mediated JNK signaling pathway

Colon cancer ranks among the most prevalent malignancies worldwide, trailing only lung and breast cancer in incidence. Despite the availability of numerous therapeutic strategies, the burden of new cases and fatalities remains high in countries undergoing socioeconomic transitions. Natural products offer promising avenues for developing more effective and less toxic anticancer agents, expanding the clinical arsenal. In this investigation, we isolated a triterpenoid, (21 S,23 R,24 R)-21,23-epoxy-24-hydroxy-21-methoxytirucalla-7,25-dien-3-one (EHMT), from the fruits of Melia azedarach L., which exhibited significant inhibitory activity against colon cancer cells while sparing normal cells. EHMT effectively curtailed colony formation and induced apoptosis and cell cycle arrest in the HCT116 cell line. Furthermore, EHMT prompted the generation of reactive oxygen species (ROS) and the depolarization of mitochondrial membrane potential. Notably, EHMT treatment triggered ROS-mediated cell apoptosis via activation of the JNK signaling pathway in HCT116 cells. Additionally, our findings extended to Caenorhabditis elegans, where EHMT induced ROS accumulation and apoptosis. Collectively, these findings position EHMT as a promising candidate for the development of anticancer agents in the treatment of colon cancer, offering new hope in the battle against this formidable disease.

Chemical derivatization strategies for enhancing the HPLC analytical performance of natural active triterpenoids

Triterpenoids widely exist in nature, displaying a variety of pharmacological activities. Determining triterpenoids in different matrices, especially in biological samples holds great significance. High-performance liquid chromatography (HPLC) has become the predominant method for triterpenoids analysis due to its exceptional analytical performance. However, due to the structural similarities among botanical samples, achieving effective separation of each triterpenoid proves challenging, necessitating significant improvements in analytical methods. Additionally, triterpenoids are characterized by a lack of ultraviolet (UV) absorption groups and chromophores, along with low ionization efficiency in mass spectrometry. Consequently, routine HPLC analysis suffers from poor sensitivity. Chemical derivatization emerges as an indispensable technique in HPLC analysis to enhance its performance. Considering the structural characteristics of triterpenoids, various derivatization reagents such as acid chlorides, rhodamines, isocyanates, sulfonic esters, and amines have been employed for the derivatization analysis of triterpenoids. This review comprehensively summarized the research progress made in derivatization strategies for HPLC detection of triterpenoids. Moreover, the limitations and challenges encountered in previous studies are discussed, and future research directions are proposed to develop more effective derivatization methods.

Betulinic acid induces apoptosis of HeLa cells via ROS-dependent ER stress and autophagy in vitro and in vivo

Betulinic acid (BA), a naturally occurring lupane-type triterpenoid, possesses a wide range of potential activities against different types of cancer. However, the molecular mechanisms involved in anti-cervical cancer about BA were rarely investigated. Herein, the role of BA in cervical cancer suppression by ROS-mediated endoplasmic reticulum stress (ERS) and autophagy was deeply discussed. The findings revealed that BA activated Keap1/Nrf2 pathway and triggered mitochondria-dependent apoptosis due to ROS production. Furthermore, BA increased the intracellular Ca2+ levels, inhibited the expression of Beclin1 and promoted the expression of GRP78, LC3-II, and p62 associated with ERS and autophagy. Besides, BA initiated the formation of autophagosomes and inhibited autophagic flux by the co-administration of BA with 3-methyladenine (3-MA) and chloroquine (CQ), respectively. The in vivo experiment manifested that hydroxychloroquine (HCQ) enhanced the apoptosis induced by BA. For the first time, we demonstrated that BA could initiate early autophagy, inhibit autophagy flux, and induce protective autophagy in HeLa cells. Thus, BA could be a potential chemotherapy drug for cervical cancer, and inhibition of autophagy could enhance the anti-tumor effect of BA. However, the interactions of signaling factors between ERS-mediated and autophagy-mediated apoptosis deserve further attention.

Integrative metabolome and transcriptome analyses reveal the differences in flavonoid and terpenoid synthesis between Glycyrrhiza uralensis (licorice) leaves and roots

Licorice from Glycyrrhiza uralensis roots is used in foods and medicines. Although we are aware that licorice roots and leaves have distinct material compositions, the specific reasons for these differences remain unknown. Comparison of the metabolomes and transcriptomes between the leaves and roots revealed flavonoids and triterpenoid saponins were significantly different. Isoflavones were enriched in roots because of upregulation of genes encoding chalcone isomerase and flavone synthase, which are involved in isoflavone synthesis. Six triterpenoid saponins were significantly enriched only in the roots. The leaves did not accumulate glycyrrhetinic acid because of low expression levels of genes involved in its synthesis. A gene encoding a UDP glycosyltransferase, which likely catalyzes the key step in the transformation of glycyrrhetinic acid to glycyrrhizin, was screened. Our results provide information about the differences in flavonoid and triterpenoid synthesis between roots and leaves, and highlight targets for genetic engineering.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01467-y.

Chaga mushroom triterpenoids as adjuncts to minimally invasive cancer therapies: A review

Cancer has become the second leading cause of death in the world. Integrative cancer therapy management is continuously evolving to enhance treatment outcomes. Chaga mushroom (Inonotus obliquus) is a parasitic fungus acclaimed to contain pharmaceutical and nutraceutical value in the fight against cancer. In particular, triterpenoid constituents derived from Chaga mushrooms have been recognized for their anti-cancer activity after distinguished cytotoxicity was repeatedly observed in cancer cells treated in vitro with lipophilic fractions of extract compared to aqueous ones. Studies that investigate the anti-cancer activity of Chaga mushroom triterpenoids are reviewed in this article to determine which cancer cell lines demonstrate the greatest susceptibility to them while highlighting the structure-activity relationships that are involved. Triterpenoid supplementation as an adjunct to cancer treatment may be a viable option as inotodiol and 3-β-22 α-dihydroxylanosta-8, 25-diene-24-one have been shown to exhibit anti-cancer activity similar to that of conventional drugs. Advances in addressing bioavailability challenges are also included in this review as studies include in vivo components.

Improvement of triterpenoid production in mycelia of Antrodia camphorata through mutagenesis breeding and amelioration of CCl4-induced liver injury in mice

Due to the scarcity of wild fruiting bodies, submerged fermentation of the medicinal fungus Antrodia camphorata is attracting much attention, but the production of bioactive triterpenoids is low. Therefore, there is an urgent need to improve the triterpenoid yield of submerged fermentation. Here, the A. camphorata mutant E3-64 was generated from strain AC16101 through random mutagenesis breeding, producing 172.8 mg triterpenoid per gram of dry mycelia. Further optimization of culture parameters resulted in a yield of 255.5 mg/g dry mycelia (i.e., an additional >1.4-fold increase), which is the highest reported yield thus far. Notably, mutant E3-64 produced 94% and 178% more of the triterpenoid components antcin A and antcamphin A, respectively, while it produced 52% and 15% less antcin B and G, respectively. Mutant E3-64 showed increased expression of key genes involved in triterpenoid biosynthesis, as well as different genome-wide single-nucleotide polymorphisms as compared with AC16101. Triterpenoids of the E3-64 mycelia exhibited remarkably protective activity against acute CCl4-induced liver injury in mice. This study shows the potential of A. camphorata for scientific research and commercial application.

Gas chromatography with mass spectrometry analysis of 4,4-dimethylsterols and 4-methylsterols in edible oils after their enrichment by means of solid phase extraction

4-Methylsterols (4-M-sterols) and 4,4-dimethylsterols (4,4-D-sterols) are a group of underexplored minor sterols that occur in almost all living organisms. Here, we developed a strategy for the determination of the biochemical precursors of the predominant 4-desmethylsterols in edible oils. Due to their low contribution to the sterol content in the samples, a solid phase extraction (SPE) method was developed for the enrichment of 4-M- and 4,4-D-sterols in the hexane extracts of saponified oils. In a two-fold SPE procedure, the bulk of 4,4-D-sterols was collected in one fraction. The residual sample was subjected to a second SPE step which targeted all 4-M-sterols and low shares of 4,4-D-sterols in one fraction and the predominant 4-desmethylsterols in another one. After silylation of the SPE fractions, gas chromatography with mass spectrometry (GC/MS) was used to analyze 4,4-D- and 4-M-sterols. The results were used to define eight subgroups whose characteristic structural features could be linked with the presence of specific m/z values. These m/z values were measured sensitively by GC/MS operated in selected ion monitoring (SIM) mode. Application of the GC/MS method to eighteen edible oils enabled the detection of 55 mostly very low abundant 4-M- and 4,4-D-sterols. Twenty-four of the 4-M- and 4,4-D-sterols could be assigned and the remaining 31 unknown sterols could be traced back to their basic structures.

Cycloartane triterpenoid from Euphorbia macrostegia modulates ER stress signaling pathways to induce apoptosis in MDA-MB231 and MCF-7 breast cancer cell lines

Unfolded protein response (UPR) is involved in breast cancer (BC) progression and drug resistance. Many natural products (NPs) could modulate UPR and used for therapeutic purposes. Herein, we aimed to investigate the molecular mechanism of Cycloart-23E-ene-3β, 25-diol (Cycloart-E25), cytotoxicity, as a NP extracted from Euphorbia macrostegia and focused on endoplasmic-reticulum stress (ERS) and UPR signaling pathways. Reactive oxygen species (ROS) were probed by DCFDA fluorescence dye. Apoptosis was assayed by annexin V/propidium iodide (PI), immunoblotting of anti- and proapoptotic, Bcl-2 and Bax proteins, and mitochondrial transmembrane potential (ΔΨm) changes. Thioflavin T (ThT) staining and immunoblotting of UPR signaling components (CHOP, PERK, ATF6, BiP, and XBP1) were recruited for the assessment of ERS. Our results indicated that Cycloart-E25 noticeably increases ROS levels in both MB-231 MDA-MB-231 and MCF-7 cell lines, p>0.05. Flow cytometry assessments revealed an increase in the cell population undergoing apoptosis. Also, the Bax/Bcl-2 ratio increased in a dose-dependent manner following Cycloart-E25 treatment, significantly, p>0.05. Mitochondrial involvement could be deduced by significant decreases in ΔΨm, p>0.05. Cycloart-E25 potently induces protein aggregation and upregulated CHOP, PERK, ATF6, BiP, and XBP1 factors in both MDA-MB-231 MB-231 and MCF-7 cell lines, indicating the involvement of ERS in Cycloart-E25-mediated apoptosis. In conclusion, Cycloart-E25 increased the accumulation of misfolded proteins and upregulated UPR components. Therefore, induction of ERS may be involved in the trigger of apoptosis in BC cell lines. Cycloart-E25 induced apoptosis in breast cancer cell lines through ERS. More assessments are needed to confirm its in vivo anti-tumoral effects.

A newly identified β-amyrin synthase gene hypothetically involved in oleanane-saponin biosynthesis from Talinum paniculatum (Jacq.) Gaertn

Talinum paniculatum or Javanese ginseng in Indonesia is a plant widely used as a traditional medicine. The genus Talinum produces oleanane-type saponins, such as talinumoside I. The first aim of this study was to isolate the probable gene encoding β-amyrin synthase (bAS), a key enzyme involved in the cyclization of 2,3-oxidosqualene producing the backbone of the oleanane-type saponin β-amyrin and characterize the gene sequence and the predicted protein sequence using in silico approach. The second aim was to analyze the correlation between the TpbAS gene expression level and saponin production in various plant organs. Thus, TpbAS was isolated using degenerate primers and PCR 5'/3'-Rapid Amplification of cDNA Ends (RACE), then the gene sequence and the predicted protein were in silico analyzed using various programs. TpbAS expression level was analyzed using reverse transcriptase PCR (RT-PCR), and saponin content was measured using a spectrophotometer. The results showed that the full-length TpbAS gene consists of 2298 base pairs encoding for a 765-amino acid protein. From in silico study, the (GA)n sequence was identified in the 5'-untranslated regions and predicted to be a candidate of the gene expression modulator. In addition, functional RNA motifs and sites analysis predicted the presence of exon splicing enhancers and silencers within the coding sequence and miRNA target sites candidate. Amino acid sequence analysis showed DCTAE, QW, and WCYCR motifs that were conserved in all classes of oxidosqualene cyclase enzymes. Phylogenetic tree analysis showed that TpbAS is closely related to other plant oxidosqualene cyclase groups. Analysis of TpbAS expression and saponin content indicated that saponin is mainly synthesized and accumulated in the leaves. Taken together, these findings will assist in increasing the saponin content through a metabolic engineering approach.

Whole-genome Duplication Reshaped Adaptive Evolution in A Relict Plant Species, Cyclocarya paliurus

Cyclocarya paliurus is a relict plant species that survived the last glacial period and shows a population expansion recently. Its leaves have been traditionally used to treat obesity and diabetes with the well-known active ingredient cyclocaric acid B. Here, we presented three C. paliurus genomes from two diploids with different flower morphs and one haplotype-resolved tetraploid assembly. Comparative genomic analysis revealed two rounds of recent whole-genome duplication events and identified 691 genes with dosage effects that likely contribute to adaptive evolution through enhanced photosynthesis and increased accumulation of triterpenoids. Resequencing analysis of 45 C. paliurus individuals uncovered two bottlenecks, consistent with the known events of environmental changes, and many selectively swept genes involved in critical biological functions, including plant defense and secondary metabolite biosynthesis. We also proposed the biosynthesis pathway of cyclocaric acid B based on multi-omics data and identified key genes, in particular gibberellin-related genes, associated with the heterodichogamy in C. paliurus species. Our study sheds light on evolutionary history of C. paliurus and provides genomic resources to study the medicinal herbs.

Inhibition of nitrogen assimilation promotes carbon-based secondary metabolism in callus of Cyclocarya paliurus

The biosynthesis and accumulation of secondary metabolites are critical important to quality formation of medicinal plants, which are usually give way to primary processes and growth. Here, methionine sulfoximine (MSO) was used to inhibit the nitrogen assimilation in callus of Cyclocarya paliurus. The newly assimilated nitrogen characterized by ¹⁵N atom percentage excess, and the levels of amino acid and protein were reduced. The other primary processes such as carbohydrate metabolism and lipid metabolism were also repressed. In addition, the expression of the growth-related target of rapamycin (TOR) signaling was repressed, indicating nitrogen assimilation inhibition led to a systematic down-regulated primary metabolisms and resulted in a disruption of growth. In contrast, the biosynthesis of flavonoids and triterpenoids, antioxidase system, and the SnRK2-mediated abscisic acid (ABA) and jasmonic acid (JA) signaling were induced, which can improve plant stress resistance and defense. Nitrogen assimilation inhibition led to the carbon metabolic flux redirection from primary processes to secondary pathways, and facilitated the biosynthesis of flavonoids and triterpenoids in calluses of C. paliurus. Our results provide a comprehensive understanding of metabolic flux redirection between primary and secondary metabolic pathways and a potential means to improve the quality of medicinal plants.

Boosting the epoxidation of squalene to produce triterpenoids in Saccharomyces cerevisiae

BACKGROUND

Polycyclic triterpenoids (PTs) are common in plants, and have attracted considerable interest due to their remarkable biological activities. Currently, engineering the ergosterol synthesis pathway in Saccharomyces cerevisiae is a safe and cost-competitive way to produce triterpenoids. However, the strict regulation of ERG1 involved in the epoxidation of squalene limits the triterpenoid production.

RESULTS

In this study, we found that the decrease in ERG7 protein level could dramatically boost the epoxidation of squalene by improving the protein stability of ERG1. We next explored the potential factors that affected the degradation process of ERG1 and confirmed that ERG7 was involved in the degradation process of ERG1. Subsequently, expression of four different triterpene cyclases utilizing either 2,3-oxidosqualene or 2,3:22,23-dioxidosqualene as the substrate in ERG7-degraded strains showed that the degradation of ERG7 to prompt the epoxidation of squalene could significantly increase triterpenoid production. To better display the potential of the strategy, we increased the supply of 2,3-oxidosqualene, optimized flux distribution between ergosterol synthesis pathway and β-amyrin synthesis pathway, and modified the GAL-regulation system to separate the growth stage from the production stage. The best-performing strain ultimately produced 4216.6 ± 68.4 mg/L of β-amyrin in a two-stage fed-fermentation (a 47-fold improvement over the initial strain).

CONCLUSIONS

This study showed that deregulation of the native restriction in ergosterol pathway was an effective strategy to increase triterpenoid production in yeast, which provided a new insight into triterpenoids biosynthesis.

Heterologous expression of Chlorophytum borivilianum Squalene epoxidase in tobacco modulates stigmasterol production and alters vegetative and reproductive growth

KEYMESSAGE

CbSE overexpression increased stigmasterol levels and altered plant morphology. The genes upstream and downstream of CbSE were found to be upregulated, which confirms its regulatory role in the saponin biosynthetic pathway. Chlorophytum borivilianum is a high-value medicinal plant with many promising preclinical applications that include saponins as a major active ingredient. Squalene epoxidase (SE) is one of the major rate-limiting enzymes of the saponin biosynthetic pathway. Here, we functionally characterized C. borivilianum SE (CbSE) by over-expressing heterologously in Nicotiana tabacum. The heterologous expression of CbSE resulted in stunted pant growth with altered leaf and flower morphology. Next, RT-qPCR analysis of transgenic plants overexpressing CbSE revealed increased expression levels of Cycloartenol synthase (CAS), Beta amyrin synthase (βAS), and cytochrome P450 monooxygenase 51 (CYP51) (Cytochrome P450), which encode key enzymes for triterpenoid and phytosterol biosynthesis in C. borivilianum. Further, Methyl Jasmonate (MeJa) treatment upregulated Squalene synthase (SQS), SE, and Oxidosqualene cyclases (OSCs) to a significant level. GC-MS analysis of the leaf and hairy roots of the transformants showed an increased stigmasterol content (0.5-1.0 fold) compared to wild type (WT) plants. These results indicate that CbSE is a rate-limiting gene, which encodes an efficient enzyme responsible for phytosterol and triterpenoid production in C. borivilianum.

Squalene epoxidase (SE) gene related to triterpenoid biosynthesis assists to select elite genotypes in medicinal plant: Cyclocarya paliurus (Batal.) Iljinskaja

Triterpenoids, known for their anti-inflammatory, anticancer, and hypoglycemic properties, are the major bioactive components in Cyclocarya paliurus (Batal.) Iljinskaja. Selecting elite individuals with high triterpenoids content is the basis of C. paliurus industry for medicinal use. In this study, seasonal variation patterns of total triterpenoids and five triterpene monomers accumulation for three groups with different total triterpenoid contents (TTC; H: 59.74-64.03 mg g^-1; M: 47.66-57.08 mg g^-1, and L: 35.26-42.22 mg g^-1) were surveyed. Seasonal expression dynamics of 6 key genes relevant to triterpenoids biosynthesis, including HMGR, DXR, SQS, SE, LUS, and β-AS, were described by quantitative real-time PCR (qRT-PCR) for three groups. The expression levels of HMGR, SE, LUS, and β-AS genes in group H were higher than in groups M and L. In addition, Pearson correlation analysis showed that they were significantly positively correlated with triterpene accumulation, and the expression level of SE gene not only was significantly correlated with downstream genes, but also exhibited a linear relationship with TTC, especially in September. These results suggest that SE gene could serve as an effective make for screening elite individuals with high TTC from the germplasm of C. paliurus for medicinal use. Further testing on randomly selected individuals in next September proved the feasibility and reliability of SE gene in assisted selection. Also, we successfully cloned the full-length cDNA of SE. Thus, our work provides an efficient way to attain superior genotypes to develop medicinal industry of C. paliurus in practice.

Anti-inflammatory lanostane triterpenoids with rearranged spirobi[indene] scaffold and their biogenetically related analogues from Euphorbia maculata

Phytochemical investigations on the ethanol extract of the whole plant of Euphorbia maculata Linn. Resulted in the identification of 16 lanostane-related triterpenoids, including 11 undescribed ones, namely spiromaculatols A-C (1-3) and euphomaculatoids A-H (4-11). The structural determinations of the previously undescribed ones (1-11) were elucidated based on the interpretation of comprehensive spectroscopic data, quantum chemical calculation, as well as X-ray crystallographic experiments. Spiromaculatols A-C (1-3) possess a rare spirobi [indane] skeleton, which was biosynthetically derived from the 7 (8 → 9)-abeo bond migration of lanostane precursors. The biological activity of compounds 1-3, 5, 7, and 12-13 displayed inhibitory effect on the release of NO in an LPS-activated RAW264.7 cells model. Molecular mechanism study indicated that the most potent spiromaculatol C (3) can reduce the nuclear translocation of NF-κB p65 and decrease the transcriptional expressions of its downstream pro-inflammatory mediators.

Triterpenoids from the leaves of Abies koreana and their biological activities

Seven undescribed triterpenoids, abikoranes A-G, along with three known triterpenoids were isolated from the leaves of Abies koreana E. H. Wilson. The structures of compounds were elucidated by 1D and 2D NMR, HRMS, ECD, specific rotation, and DP4+ analysis. Abikorane A represents the second example of nor-3,4-seco-17,14-friedo-lanostane triterpenoid. Among the isolates, some compounds showed strong cytotoxic activities against some of four tested cancer cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-116) with the values of IC₅₀ 0.89-9.62 μM, inhibited lipopolysaccharide-stimulated nitric oxide production with IC₅₀ values of 11.57-15.16 μM, and exhibited significant nerve growth factor release effect (192.54 ± 12.33%) from C6 glioma cells.

Chemical constituents isolated from Actinidia polygama and their α-glucosidase inhibitory activity and insulin secretion effect

Actinidia polygama has been used as a traditional medicine for treating various diseases. In the present study, 13 compounds, including three new monoterpenoids (1-3), were isolated from the leaves of A. polygama to investigate the bioactive constituents of the plant. The structures were characterized by analyzing spectroscopic and chiroptical data. These compounds were preliminarily screened for their ability to increase insulin secretion levels after glucose stimulation. Of these, 3-O-coumaroylmaslinic acid (4) and jacoumaric acid (5) showed activity. In further biological studies, these compounds exhibited increased glucose-stimulated insulin secretion (GSIS) activity without cytotoxicity in rat INS-1 pancreatic β-cells as well as α-glucosidase inhibitory activity. Furthermore, both compounds increased insulin receptor substrate-2 (IRS-2), phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), pancreatic and duodenal homeobox-1 (PDX-1), and peroxisome proliferator-activated receptor-γ (PPAR-γ) expression. Hence, these compounds may be developed as potential antidiabetic agents.

Structural diversity, fermentation production, bioactivities and applications of triterpenoids from several common medicinal fungi: Recent advances and future perspectives

Medicinal fungi are beneficial to human health and it reduces the risk of chronic diseases. Triterpenoids are polycyclic compounds derived from the straight-chain hydrocarbon squalene, which are widely distributed in medicinal fungi. Triterpenoids from medicinal fungal sources possess diverse bioactive activities such as anti-cancer, immunomodulatory, anti-inflammatory, anti-obesity. This review article describes the structure, fermentation production, biological activities, and application of triterpenoids from the medicinal fungi including Ganoderma lucidum, Poria cocos, Antrodia camphorata, Inonotus obliquus, Phellinus linteus, Pleurotus ostreatus, and Laetiporus sulphureus. Besides, the research perspectives of triterpenoids from medicinal fungi are also proposed. This paper provides useful guidance and reference for further research on medicinal fungi triterpenoids.

Novel Ganoderma triterpenoid saponins from the biotransformation-guided purification of a commercial Ganoderma extract

Ganoderma sp. contains high amounts of diverse triterpenoids; however, few triterpenoid saponins could be isolated from the medicinal fungus. To produce novel Ganoderma triterpenoid saponins, biotransformation-guided purification (BGP) process was applied to a commercial Ganoderma extract. The commercial Ganoderma extract was partially separated into three fractions by preparative high-performance liquid chromatography, and the separated fractions were then directly biotransformed by a Bacillus glycosyltransferase (BsUGT489). One of the biotransformed products could be further purified and identified as a novel saponin: ganoderic acid C2 (GAC2)-3-O-β-glucoside by nucleic magnetic resonance (NMR) and mass spectral analyses. Based on the structure of the saponin, the predicted precursor should be the GAC2, which was confirmed to be biotransformed into four saponins, GAC2-3-O-β-glucoside, GAC2-3,15-O-β-diglucoside and two unknown GAC2 monoglucosides, revealed by NMR and mass spectral analyses. GAC2-3-O-β-glucoside and GAC2-3,15-O-β-diglucoside possessed 17-fold and 200-fold higher aqueous solubility than that of GAC2, respectively. In addition, GAC2-3-O-β-glucoside retained the most anti-α-glucosidase activity of GAC2 and was comparable with that of the anti-diabetes drug (acarbose). The present study showed that the BGP process is an efficient strategy to survey novel and bioactive molecules from crude extracts of natural products.

pallida

ABSTRUCT: n-Hexane extract of rhizomes of Imperata cylindrica var. koenigii f. pallida yielded five novel skeletal triterpenoids, designed as impallidin (1), impallidol (2), impallidin ozonide (3a, 3b), trisnorimpallidin aldehyde (4), tetranorimpallidin aldehyde (5). Structures of novel compounds were elucidated by mainly 2D NMR and other spectroscopic analysis and chemical correlations. Alternatively, compound 3a, 3b was derivatized from 1 under ozone oxidation condition.

Ganoapplins A and B with an unprecedented 6/6/6/5/6-fused pentacyclic skeleton from Ganoderma inhibit Tau pathology through activating autophagy

Ganoapplins A and B (1 and 2) with a 6/6/6/5/6-fused pentacyclic skeleton containing an aromatic E ring, were obtained from Ganoderma applanatum. Their structures were established through extensive spectroscopic analyses, quantum chemical calculations, including calculated chemical shifts with DP4 + analysis and electronic circular dichroism (ECD). A plausible biosynthetic pathway for 1 and 2 was proposed. Furthermore, their roles in activating autophagy were investigated and the cellular assays showed that 1 and 2 can inhibit tau pathology by inducing autophagy, suggesting their potential against Alzheimer's disease (AD).

Discovery of pentacyclic triterpenoid glycosides with anti-proliferative activities from Ardisialindleyana

One new pentacyclic triterpenoid glycoside, ardisiapunine E (1), along with two known compounds were isolated from the root of Ardisia lindleyana D.Dietr. Their structures were elucidated by ¹H and ¹³C NMR, DEPT, HMBC, HSQC, ¹H-¹H COSY and NOESY spectroscopic analyses, ESI-MS, and literature. Compounds 1-3 exhibited obvious anti-proliferative activities against the HeLa cell line in a dose- and time-dependent manner by inducing G2/M phase arrest and apoptosis in vitro, both consisting of pentacyclic triterpenes and sugar. Hence, this study identified a new and two known pentacyclic triterpenoid glycosides promoting apoptosis as a potential anti-proliferative agent.

Anti-inflammatory and anti-oxidant properties of Melianodiol on DSS-induced ulcerative colitis in mice

Background

Ulcerative colitis is a unique inflammatory bowel disease with ulcerative lesions of the colonic mucosa. Melianodiol (MN), a triterpenoid, isolated from the fruits of the Chinese medicinal plant Melia azedarach, possesses significant anti-inflammatory properties.

Objective

The present study investigated the protective effects of MN on lipopolysaccharide (LPS)-induced macrophages and DSS-mediated ulcerative colitis in mice.

Methods

In the study, mice were given MN (50, 100, and 200 mg/kg) and 5-ASA (500 mg/kg) daily for 9 days after induction by DSS for 1 week. The progress of the disease was monitored daily by observation of changes in clinical signs and body weight.

Results

The results showed that MN effectively improved the overproduction of inflammatory factors (IL-6, NO, and TNF-α) and suppressed the activation of the NF-κB signalling cascade in LPS-mediated RAW264.7 cells. For DSS-mediated colitis in mice, MN can reduce weight loss and the disease activity index (DAI) score in UC mice, suppress colon shortening, and alleviate pathological colon injury. Moreover, MN treatment notably up regulated the levels of IL-10 and down regulated those of IL-1β and TNF-α, and inhibited the protein expression of p-JAK2, p-STAT3, iNOS, NF-κB P65, p-P65, p-IKKα/β, and p-IκBα in the colon. After MN treatment, the levels of MDA and NO in colonic tissue were remarkably decreased, whereas the levels of GSH, SOD, Nrf-2, Keap-1, HO-1, IκBα, and eNOS protein expression levels were significantly increased.

Conclusion

These results indicate that MN can activate the Nrf-2 signalling pathway and inhibit the JAK/STAT, iNOS/eNOS, and NF-κB signalling cascades, enhance intestinal barrier function, and effectively reduce the LPS-mediated inflammatory response in mouse macrophages and DSS-induced intestinal injury in UC.

Heilaohuacid G, a new triterpenoid from Kadsura coccinea inhibits proliferation, induces apoptosis, and ameliorates inflammation in RA-FLS and RAW 264.7 cells via suppressing NF-𝜅B pathway

Heilaohu, the roots of Kadsura coccinea, has been used in Tujia ethnomedicine to treat rheumatic arthritis (RA). Heilaohuacid G (1), a new 3,4-seco-lanostane type triterpenoid isolated from the ethanol extract of Heilaohu, whose structure was determined using HR-ESI-MS data, NMR spectroscopic analyses, and ECD calculations. In this study, our purpose is to elucidate the mechanisms of Heilaohuacid G in the treatment of RA by inhibited proliferation of rheumatoid arthritis-fibroblastoid synovial (RA-FLS) cells and inhibited the inflammatory reactions in LPS-induced RA-FLS and RAW 264.7 cell lines via inhibiting NF-κB pathway. The biological activity screening experiments indicated that Heilaohuacid G significantly inhibited proliferation of RA-FLS cells with IC50 value of 8.16 ± 0.47 μM. CCK-8 assay, ELISA, flow cytometry assay, and Western blot were used to measure the changes of cell viability, apoptosis, and the release of inflammatory cytokines. Heilaohuacid G was found not only induced RA-FLS cell apoptosis, but also inhibited the inflammatory reactions in LPS-induced RA-FLS and RAW 264.7 cell lines via inhibiting NF-κB pathway. Furthermore, Heilaohuacid G (p.o.) at doses of 3.0, 6.0, and 12.0 mg/kg and the ethanol extracts of Heilaohu (p.o.) at doses of 200, 400, and 800 mg/kg both were confirmed antiinflammatory effects on xylene-induced ear mice edema model.

Enhanced production of amyrin in Yarrowia lipolytica using a combinatorial protein and metabolic engineering approach

BACKGROUND

Amyrin is an important triterpenoid and precursor to a wide range of cosmetic, pharmaceutical and nutraceutical products. In this study, we metabolically engineered the oleaginous yeast, Yarrowia lipolytica to produce α- and β-amyrin on simple sugar and waste cooking oil.

RESULTS

We first validated the in vivo enzymatic activity of a multi-functional amyrin synthase (CrMAS) from Catharanthus roseus, by expressing its codon-optimized gene in Y. lipolytica and assayed for amyrins. To increase yield, prevailing genes in the mevalonate pathway, namely HMG1, ERG20, ERG9 and ERG1, were overexpressed singly and in combination to direct flux towards amyrin biosynthesis. By means of a semi-rational protein engineering approach, we augmented the catalytic activity of CrMAS and attained ~ 10-folds higher production level on glucose. When applied together, protein engineering with enhanced precursor supplies resulted in more than 20-folds increase in total amyrins. We also investigated the effects of different fermentation conditions in flask cultures, including temperature, volumetric oxygen mass transfer coefficient and carbon source types. The optimized fermentation condition attained titers of at least 100 mg/L α-amyrin and 20 mg/L β-amyrin.

CONCLUSIONS

The design workflow demonstrated herein is simple and remarkably effective in amplifying triterpenoid biosynthesis in the yeast Y. lipolytica.

Naphthoquinones and triterpenoids from Arnebia euchroma (Royle) Johnst and their hypoglycemic and lipid-lowering effects

A new pentacyclic triterpenoid, 2-hydroxy-1-ene-hydroxyhopanone (19), and a new benzoxepin-5-one, 3-(4-methyl-3-penten-1-yl)-6-hydroxy-9-methoxy-2H-1-benzoxepin-5-one (25), along with 26 known compounds (1-18, 20-24, 26-28), were isolated from the roots of Arnebia euchroma (Royle) Johnst. The structures of the new compounds were elucidated by extensive spectroscopic analyses. The absolute configurations of shikonofurans 9-13 were determined by quantum chemical ECD calculations and CD spectra comparison for the first time. Pharmacological study revealed that naphthoquinones 1-5, 7, and 8 had obvious cytotoxicity toward human lung adenocarcinoma A549 cell line. Meanwhile, the hypoglycemic and lipid-lowering effects of isolated compounds were assessed by checking their inhibitory effects on key enzymes regulating glucose and lipid metabolism. Results showed that compounds 1, 3, 5, 6, 8, 18, and 19 could inhibit the activity of ATP-citrate lyase (ACL); compound 7 could inhibit the activity of acetyl-CoA carboxylase (ACC1); while compounds 8 and 19 showed inhibitory effects on protein tyrosine phosphatase 1B (PTP1B). Among them, the naphthoquinone 6, steroid 18, and triterpenoid 19 showed moderate inhibitory effects on ACL and PTP1B, but didn't exhibit obvious cytotoxicity. This study demonstrated that compounds 6, 18, and 19 show great promising for the development of new agents for the treatment of metabolic diseases.

Undescribed abietane-type diterpenoids and oleanane-type triterpenoids from the stem and branch of Tripterygium wilfordii

Six undescribed abietane-type diterpenoids (tripterydinoids A-F) and five undescribed oleanane-type triterpenoids (tripterytrinoids A-E) were obtained and determined from the stem and branch of Tripterygium wilfordii Hook. f. (Celastraceae). Tripterydinoids A-C possessed the abietane-type diterpenoid skeleton with rare 8, 9-epoxy ring. The structures of undescribed compounds were established by extensive spectroscopic studies [HRESIMS, 1D/2D-NMR and electronic circular dichroism (ECD) calculation]. The absolute configurations of tripterydinoids A, B, E and tripterytrinoid A were defined by X-ray crystallographic analyses. Bioactivity screening indicated that tripterydinoids A-C exhibited potent inhibitory effects against NO release in LPS-activated RAW 264.7 macrophages with IC₅₀ values of 6.93, 4.46 and 2.98 μM, respectively. Meanwhile, tripterydinoids A-D and tripterytrinoids B, C showed moderate and selective cytotoxicities against five human tumor cell lines (A375, Huh7, MCF-7, HCT-116 and NCI-H460).

Design, synthesis, and bio-evaluation of novel triterpenoid derivatives as anti-HIV-1 compounds

Two betulinic acid derivatives, RPR103611 (2) and IC9564 (3) were previously reported to be potent HIV-1 entry inhibitors. In this current study, a SAR study of the triterpenoid moiety of 2 and 3 has been performed and an oleanolic acid derivative (4) was identified as a novel HIV-1 entry inhibitor. In addition, the combination of 4 with several-type of HIV-1 neutralizing antibodies provided significant synergistic effects. The synthetic utility of the CC double bond in the C-ring of 4 was also demonstrated to develop the 12-keto-type oleanolic acid derivative (5) as a potent anti-HIV compound. This simple transformation led to a significantly increased anti-HIV activity and a reduced cytotoxicity of the compound.

Brujavanoids A-U, structurally diverse apotirucallane-type triterpenoids from Brucea javanica and their anti-inflammatory effects

Extensive phytochemical investigation on the methanol extract of the inflorescences, twigs, and leaves of Brucea javanica led to the isolation and identification of 27 triterpenoids, including 21 previously undescribed ones, named brujavanoids A-U (1-21). Their structures were determined based on comprehensive spectroscopic analysis and single-crystal X-ray diffraction. Of these compounds, brujavanoid A (1) represents the first apotirucallane-type triterpenoid with a novel 19(10 → 9)abeo motif, and brujavanoids B and C (2-3) are the first apotirucallane-type triterpenoids with a rarely occurring 14-hydorxy-15,16-epoxy fragment. All the isolates were evaluated for their anti-inflammatory effect in an LPS-activated RAW264.7 cells model. Furthermore, the most active one, brujavanoid E (5), can suppress the transcriptional expression of typical pro-inflammatory mediators and inhibit the nuclear translocation of NF-κB p65 in the LPS- activated RAW264.7 cells.

Molecular pharmacology and therapeutic advances of the pentacyclic triterpene lupeol

BACKGROUND

Plant triterpenoids are major sources of nutraceuticals that provide many health benefits to humans. Lupeol is one of the pentacyclic dietary triterpenoids commonly found in many fruits and vegetables, which is highly investigated for its pharmacological effect and benefit to human health.

PURPOSE

This systematic review critically discussed the potential pharmacological benefits of lupeol and its derivatives as evidenced by various cellular and animal model studies. To gain insight into the pharmacological effects of lupeol, the network pharmacological approach is applied. Pharmacokinetics and recent developments in nanotechnology-based approaches to targeted delivery of lupeol along with its safety use are also discussed.

METHODS

This study is dependent on the systematic and non-exhaustive literature survey for related research articles, papers, and books on the chemistry, pharmacological benefits, pharmacokinetics, and safety of lupeol published between 2011 and 2021. For online materials, the popular academic search engines viz. Google Scholar, PubMed, Science Direct, Scopus, ResearchGate, Springer, as well as official websites were explored with selected keywords.

RESULTS

Lupeol has shown promising benefits in the management of cancer and many other human diseases such as diabetes, obesity, cardiovascular diseases, kidney and liver problems, skin diseases, and neurological disorders. The pharmacological effects of lupeol primarily rely on its capacity to revitalize the cellular antioxidant, anti-inflammatory and anti-apoptotic mechanisms. Network pharmacological approach revealed some prospective molecular targets and pathways and presented some significant information that could help explain the pharmacological effects of lupeol and its derivatives. Despite significant progress in molecular pharmacology, the clinical application of lupeol is limited due to poor bioavailability and insufficient knowledge on its mode of action. Structural modification and nanotechnology-guided targeted delivery of lupeol improve the bioavailability and bioactivity of lupeol.

CONCLUSION

The pentacyclic triterpene lupeol possesses numerous human health-benefiting properties. This review updates current knowledge and critically discusses the pharmacological effects and potential applications of lupeol and its derivatives in human health and diseases. Future studies are needed to evaluate the efficacies of lupeol and its derivatives in the management and pathobiology of human diseases.

Identification of seven undescribed cucurbitacins in Cucumis sativus (cucumber) and their cytotoxic activity

Cucurbitacin C-type cucurbitacins that are only identified in Cucumis sativus (cucumber) are, in part, responsible for the health benefits and bitter flavor. Nevertheless, detailed information about those functional ingredients in cucumber is scarce. In this study, ten cucurbitacin C analogues including seven undescribed ones have been isolated from the bitter leaves of cucumber, in which six compounds showed growth inhibition capabilities against tumor cell lines HepG2, A549, DU145 and HCT116. Intriguingly, cucurbitacin C6 and C7 exhibited a significant inhibition effect compared to the positive control taxol (IC₅₀ = 1.86 ± 0.17 μM) on HepG2 cell line with IC₅₀ values of 10.06 ± 0.34 μM and 4.16 ± 0.42 μM, respectively. The mechanism of cucurbitacin-induced apoptosis is likely down-regulating the expression of caspase-related proteins. This work enlarges the knowledge of the cucurbitacins in cucumber and highlights the importance of cucumber as a source of specialized metabolites in the food and medicinal industries.

Triterpenoids impede the fibrillation and cytotoxicity of human islet amyloid polypeptide

The inhibition of human islet amyloid polypeptide (hIAPP) deposition to block its toxicity is an important strategy for the prevention and treatment of type II diabetes mellitus (T2DM).Natural compounds with pharmacological properties and low toxicity can serve as a good point to discover potential inhibitors of protein misfolding, which may be useful for the treatment of various amyloidosis-related diseases. Previous studies have reported that triterpenoids, such as maslinic acid (MA) and momordicin I (MI), can modulate glucose metabolism partially by reducing insulin resistance. However, the internal antidiabetic mechanism of these triterpenoids remains unclear. In this study, we examined the inhibition and disaggregation of MAandits isomer MI on the fibrillation of hIAPP using various experimental and computational approaches. The assembly behaviors and peptide-induced cytotoxicity of hIAPP could be effectively resisted by MA and MI. Moreover, the interaction of the two triterpenoids with hIAPP displayed a spontaneous and exothermic process. Moreover, molecular dynamics simulation results of different peptides revealed that MA and MI could bind to Asn and other non-polar residues near the core C-terminal region and reduce the oligomerization of hIAPP. The binding affinity was predominantly contributed by hydrophobic, electrostatic and hydrogen bonding interactions. The present work provides valuable data for MA and MI to treat T2DM and amyloidosis-related diseases.

A novel carotenoid biosynthetic route via oxidosqualene

Over 800 known carotenoids are synthesized from phytoene or 4,4'-diapophytoene (dehydrosqualene) characterized by three conjugated double bonds. In this paper, we report that carotenoid desaturase CrtN from Staphylococcus aureus and Methylomonas can accept oxidosqualene, which is the precursor for plant- or animal-type triterpenoids, yielding the yellow carotenoid pigments with 8, 9, or 10 conjugated double bonds. The resulting pathway is the second nonnatural route for carotenoid pigments and the first pathway for carotenoid pigments not biosynthesized via (diapo)phytoene.

Extracts of Poria cocos improve functional dyspepsia via regulating brain-gut peptides, immunity and repairing of gastrointestinal mucosa

BACKGROUND

Poria cocos (Schw.) Wolf (PC), a fungus, has been used for more than 2000 years as a food and medicine in China. It has a very good therapeutic effect for functional dyspepsia (FD). However, the material basis and mechanism of PC on FD were not reported.

PURPOSE

To investigate the function and potential mechanisms of PC including its three extracts (triterpenoid, PCT; water-soluble polysaccharide, PCWP; acidic polysaccharide, PCAP) on FD.

STUDY DESIGN

The study explored the therapeutic effect of PC and its three extracts on FD in rats for the first time and discussed its mechanisms based on brain-gut peptides, immunity and repair of the gastrointestinal mucosa.

METHODS

The chemical components of PC extracts were analyzed and quantified using ultra high performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS) and gel permeation chromatography coupled with size exclusion chromatography (GPC/SEC). The FD rat models were established using weight-loaded forced swimming and alternate-day fasting for 42 days. After 14 days of treatment, the effect and mechanisms were investigated using ELISA, histopathology, immunohistochemistry as well as Western blot.

RESULTS

Seventy-seven triterpenoids in PCT were identified. PCWP was primarily composed of component A (Mw: 3.831 × 10⁷ Da), component B (Mw: 5.650 × 10⁶ Da) and component C (Mw: 113,117 Da). PCAP was a homogeneous composition with an average Mw of 74,320 Da. PCT, PCWP and PCAP alleviated the symptoms of FD. These extracts promoted the repair of gastrointestinal mucosa and regulated the balance between the T helper cell (Th)1/Th2 axis and the Th17/Treg axis. PCT and PCWP regulated brain-gut peptides more effectively, PCWP and PCAP enhanced immunity more effectively. Further study demonstrated that these extracts may have enhanced immunity via the Toll-like receptor (TLR) and c-Jun N-terminal kinase (JNK) signaling pathways.

CONCLUSIONS

PC extracts showed therapeutic effects on FD rats, and the mechanism of action involved multiple pathways. PCAP, which is often discarded in traditional applications, was effective. Our study provides new ideas for the application and development of PC extracts.

Biosynthesis of a novel ganoderic acid by expressing CYP genes from Ganoderma lucidum in Saccharomyces cerevisiae

Ganoderic acids (GAs), a group of highly oxygenated lanostane-type triterpenoids from the traditional Chinese medicinal mushroom Ganoderma lucidum, possessed significant pharmacological activities. Due to the difficulty in its genetic manipulation, low yield, and slow growth of G. lucidum, biosynthesis of GAs in a heterologous host is a promising alternative for their efficient production. Heterologous production of a GA, 3-hydroxy-lanosta-8,24-dien-26-oic acid (HLDOA), was recently achieved by expressing CYP5150L8 from Ganoderma lucidum in Saccharomyces cerevisiae, but post-modification of HLDOA to biosynthesize other GAs remains unclear. In this study, another P450 from G. lucidum, CYP5139G1, was identified to be responsible for C-28 oxidation of HLDOA, resulting in the formation of a new GA 3,28-dihydroxy-lanosta-8,24-dien-26-oic acid (DHLDOA) by the engineered yeast, whose chemical structure was confirmed by UPLC-APCI-HRMS and NMR. In vitro enzymatic experiments confirmed the oxidation of HLDOA to DHLDOA by CYP5139G1. As the DHLDOA production was low (0.27 mg/L), to improve it, the strategy of adjusting the dosage of hygromycin and geneticin G418 to respectively manipulate the copy number of plasmids pRS425-Hyg-CYP5150L8-iGLCPR (harboring CYP5150L8, iGLCPR, and hygromycin-resistant gene hygR) and pRS426-KanMx-CYP5139G1 (harboring CYP5139G1 and G418-resistant gene KanMx) was adopted. Finally, 2.2 mg/L of DHLDOA was obtained, which was 8.2 fold of the control (without antibiotics addition). The work enriches the GA biosynthetic enzyme library, and is helpful to construct heterologous cell factories for other GA production as well as to elucidate the authentic GA biosynthetic pathway in G. lucidum. KEY POINTS: • Another P450 gene responsible for GA's post-modification was discovered and identified. • One new GA, DHLDOA, was identified and produced via engineered yeast. • With the balance of the two CYP genes expression, DHLDOA production was significantly improved.

Heme oxygenase-1/carbon monoxide signaling participates in the accumulation of triterpenoids of Ganoderma lucidum

Ganoderic triterpenoids (GTs) are the primary bioactive constituents of the Basidiomycotina fungus, Ganoderma lucidum. These compounds exhibit antitumor, anti-hyperlipidemic, and immune-modulatory pharmacological activities. This study focused on GT accumulation in mycelia of G. lucidum mediated by the heme oxygenase-1 (HO-1)/carbon monoxide (CO) signaling. Compared with the control, hemin (10 μmol/L) induced an increase of 60.1% in GT content and 57.1% in HO-1 activity. Moreover, carbon monoxide-releasing molecule-2 (CORM-2), CO donor, increased GT content by 56.0% and HO-1 activity by 18.1%. Zn protoporphyrin IX (ZnPPIX), a specific HO-1 inhibitor, significantly reduced GT content by 26.0% and HO-1 activity by 15.8%, while hemin supplementation reversed these effects. Transcriptome sequencing showed that HO-1/CO could function directly as a regulator involved in promoting GT accumulation by regulating gene expression in the mevalonate pathway, and modulating the reactive oxygen species (ROS) and Ca²⁺ pathways. The results of this study may help enhance large-scale GT production and support further exploration of GT metabolic networks and relevant signaling cross-talk.

Cytotoxic triterpenoids from Chisocheton pentandrus

Eleven undescribed triterpenoids (pentandrucines A to K) were isolated from the n-hexane extract of the stem bark of Chisocheton pentandrus (Blanco) Merr. These comprised ten undescribed dammarane-type triterpenoids and one undescribed apotirucallane-type triterpenoid. Additionally, two dammarane-type triterpenoids, four apotirucallane-type triterpenoids and two tirucallane-type triterpenoids were also isolated. The chemical structures of pentandrucine A-K, were fully elucidated using 1D and 2D-NMR, and high resolution MS. All of the compounds were evaluated for cytotoxic activity against MCF-7 breast cancer cells in vitro. Melianodiol proved to be the most active with an IC₅₀ of 16.84 μM comparing favourably with Cisplatin (13.2 μM).

Structurally diverse triterpenoids with cytotoxicity from Euphorbia hypericifolia

Extensive phytochemical investigation on the whole herbs of Euphorbia hypericifolia led to the isolation of 18 structurally diverse tetracyclic and pentacyclic triterpenoids, including four 4α,14α-dimethyl-5α-ergostanes (1-4), two seco-adiananes (5 and 6), three dammaranes (7-9), four cycloartanes (10-13), one tirucallane (14), two fernanes (15 and 16), one ursane (17), and one oleanane (18). Among them, euphypenoids A (1) and B (5) were new triterpenoids. Their structures were elucidated on the basis of extensive spectroscopic analysis, single-crystal X-ray diffraction, and chemical transformation. All isolates were screened for their cytotoxic activities against the colorectal cancer cell line HCT-116, and compounds 1, 12, and 15 showed remarkable activities with IC50 values of 12.8 ± 1.6, 7.4 ± 0.2, and 10.6 ± 1.2 μM, respectively.

α-Glucosidase inhibitory and anti-inflammatory activities of dammarane triterpenoids from the leaves of Cyclocarya paliurus

Diabetes mellitus is caused by chronic inflammation and affects millions of people worldwide. Cyclocarya paliurus leaves have been widely used in traditional folk tea as a remedy for diabetes, but the antidiabetic constituents remain to be further studied. The α-glucosidase inhibitory and anti-inflammatory activities were examined to evaluate their effects on diabetes mellitus, and bioassay-guided separation of C. paliurus leaves led to the identification of twenty dammarane saponins, including eleven new dammarane saponins (1-11). The structures of the isolates were elucidated by spectroscopic methods. Bioactivity assay results showed that compounds 1 and 2 strongly inhibited α-glucosidase activity, with IC50 values ranging from 257.74 μM, 282.23 μM, and strongly inhibited the release of NO, with IC50 values of 9.10 μM, 9.02 μM. Moreover, compound 2 significantly downregulated the mRNA expression of iNOS, COX-2, IL-1β, NF-κB, IL-6 and TNF-α in LPS-mediated RAW 264.7 cells and markedly suppressed the protein expression of iNOS, NF-κB/p65, and COX-2. Dammarane glucoside 2 exhibited the strongest α-glucosidase inhibitory and anti-inflammatory activities. In addition, the structure-activity relationships (SARs) of the dammarane saponins were investigated. In summary, C. paliurus leaves showed marked α-glucosidase inhibitory and anti-inflammatory activities, and dammarane saponins are responsible for regulating α-glucosidase, inflammatory mediators, and mRNA and the protein expression of proinflammatory cytokines, which could be meaningful for discovering new antidiabetic agents.

Metabolite pattern in root nodules of the actinorhizal plant Casuarina equisetifolia

Casuarina equisetifolia L. (Casuarinaceae), an actinorhizal plant, exhibits mutualistic symbiosis with Frankia and promotes nitrogen fixation in root nodules. While the exchange of metabolites between host plant and microsymbiont is well understood in legume symbioses, the situation in the symbiosis between nitrogen-fixing Frankia and actinorhizal plants is less clear. In this study, a metabolomic approach was applied to root nodules of mature C. equisetifolia trees, leading to the identification of an undescribed taraxerane-type triterpenoid ester, 3-O-dihydrocoumaroyl β-taraxerol, along with twelve known compounds. An abundant component was tyramine with a content of 2.76 ± 0.315 mg/g FW in mature nodules. Tyramine specifically and abundantly accumulated in mature nitrogen-fixing nodules compared to senescent nodules, stems, leaves, and seeds. In addition, the potential function of tyramine was preliminarily examined and discussed.

Allylic Hydroxylation Activity Is a Source of Saponin Chemodiversity in the Genus Glycyrrhiza

Licorice (Glycyrrhiza) produces glycyrrhizin, a valuable triterpenoid saponin, which exhibits persistent sweetness and broad pharmacological activities. In the genus Glycyrrhiza, three species, Glycyrrhiza uralensis, Glycyrrhiza glabra and Glycyrrhiza inflata, produce glycyrrhizin as their main triterpenoid saponin, which has a ketone group at C-11. Other Glycyrrhiza species produce mainly oleanane-type saponins, which harbor homoannular or heteroannular diene structures that lack the C-11 ketone. Although the glycyrrhizin biosynthetic pathway has been fully elucidated, the pathway involving saponins with diene structures remains unclear. CYP88D6 from G. uralensis is a key enzyme in glycyrrhizin biosynthesis, catalyzing the sequential two-step oxidation of β-amyrin at position C-11 to produce 11-oxo-β-amyrin. In this study, we evaluated the functions of CYP88D6 homologs from the glycyrrhizin-producing species G. glabra and G. inflata and from the non-glycyrrhizin-producing species Glycyrrhiza pallidiflora and Glycyrrhiza macedonica, using yeast engineered to supply β-amyrin as a substrate. Yeast expressing CYP88D6 homologs from glycyrrhizin-producing species produced 11-oxo-β-amyrin. However, yeast expressing CYP88D6 homologs (such as CYP88D15) from the non-glycyrrhizin-producing Glycyrrhiza species accumulated oleana-9(11),12-dien-3β-ol and oleana-11,13(18)-dien-3β-ol; these diene compounds are non-enzymatic or yeast endogenous enzymatic dehydration derivatives of 11α-hydroxy-β-amyrin, a direct reaction product of CYP88D15. These results suggest that the activities of CYP88D6 homologs, particularly their ability to catalyze the second oxidation, could influence glycyrrhizin productivity and diversify the chemical structures of saponins in Glycyrrhiza plants. A synthetic biological approach to engineer CYP88D15 could enable the production of pharmacologically active saponins with diene structures, such as saikosaponins, whose biosynthetic pathways have yet to be fully characterized.

Bioactive naphthoquinones and triterpenoids from the fruiting bodies of Taiwanofungus salmoneus

Drug resistance of cancer cells stands for the major problem of the treatment failure for chemotherapy or target therapy. Overexpression of efflux pumps leading to multidrug resistance (MDR) is still an important issue needed to be solved. In the present study, Taiwanofungus salmoneus was selected as the topic and eleven undescribed constituents including four naphthoquinones salmonones A-D (1-4) and seven triterpenoids salmoneatins A-G (5-11), along with one chromanone (12) and two benzenoids (13 and 14) reported from the natural sources for the first time, as well as twenty-one known compounds were characterized. The structures of undescribed compounds were established by the spectroscopic and spectrometric analyses. In addition, the plausible biosynthetic mechanism of purified naphthoquinones was proposed and these compounds may be the excellent chemotaxonomic markers. Moreover, the isolates were evaluated for their P-gp inhibitory effects and the results showed that most of the examined compounds were effective. Among the tested compounds, 5, 10, 2,3-dimethoxy-5-(2',5'-dimethoxy-3',4'-methylenedioxyphenyl)-7-methyl-[1,4]naphthoquinone, zhankuic acid A methyl ester, and camphoratin F can reverse the resistance of paclitaxel or vincristine with the reversal folds in the range of 51093.3 and 259.5. These experimental data would initiate the possible development of Taiwanofungus salmoneus for the cancer therapy in the future.

Saponin toxicity as key player in plant defense against pathogens

Microbial pathogens attack every plant tissue, including leaves, roots, shoots, and flowers during all growth stages. Thus, they cause several diseases resulting in a plant's failure or loss of the whole crop in severe cases. To combat the pathogens attack, plants produce some biologically active toxic compounds known as saponins. The saponins are secondary metabolic compounds produced in healthy plants with potential anti-pathogenic activity and serve as potential chemical barriers against pathogens. Saponins are classified into two major groups the steroidal and terpenoid saponins. Here, we reported the significance of saponin toxins in the war against insect pests, fungal, and bacterial pathogens. Saponins are present in both cultivated (chilies, spinach, soybean, quinoa, onion, oat, tea, etc.) and wild plant species. As they are natural toxic constituents of plant defense, breeders and plant researchers aiming to boost plant imm unity should focus on transferring these compounds in cash crops.

Triterpenoids from the genus Gynostemma: Chemistry and pharmacological activities

ETHNOPHARMACOLOGICAL RELEVANCE

G. pentaphyllum, also known as Jiao-Gu-Lan, has been used traditionally as folk remedies for many diseases, including diabetes mellitus, metabolic syndrome, aging, and neurodegenerative diseases in China and some countries in East and Southeast Asia. It is considered as an "immortality herb" in Guizhou Province, because it was consumed regularly by the elderly native inhabitants. Other species of the same genus Gynostemma such as G. longipes and G. laxum have been used as alternatives to G. pentaphyllum in ethno-medicine in Vietnam and other Asian countries.

AIM OF THE REVIEW

The review aims to summarize up-to-date study results on Gynostemma species, including traditional usage, phytochemical profile, pharmacological activities, and toxicological studies, in order to suggest future research orientation and therapeutic applications on acute and chronic diseases.

MATERIALS AND METHODS

The relevant literature on the genus Gynostemma was gathered from secondary databases (Web of Science and PubMed), books, and official websites. The latest literature cited in this review was published in February 2020.

RESULTS

The genus Gynostemma has been widely used in traditional medicine, mainly for treatment of diabetes, hypertension, obesity, and hepatosteatosis. To date, 328 dammarane-type saponins were isolated and structurally elucidated from Gynostemma species. Crude extracts, saponin-rich fractions (gypenosides), and pure compounds were reported to show a wide range of pharmacological activities in both in vitro and in vivo experiments. The most notable pharmacological effects were anti-cancer, cardioprotective, hepatoprotective, neuroprotective, anti-diabetic, anti-obesity, and anti-inflammatory activities. Toxicological studies were conducted only on G. pentaphyllum, showing that the plant extracts were relatively safe in both acute and long-term toxicity experiments at the given dosage while no toxicological studies were reported for the other species.

CONCLUSIONS

The review summarizes current studies on traditional uses, phytochemistry, biological properties, and toxicology of medicinal Gynostemma species. Till now, the majority of publications still focused only on G. pentaphyllum. However, the promising preliminary data of other Gynostemma species indicated the research potential of this genus, both in phytochemical and pharmacological aspects. Furthermore, clinical data are required to evaluate the efficacy and undesired effects of crude extracts, standard saponin fractions, and pure compounds prepared from Gynostemma medicinal plants.

Triterpenoids from Walsura trichostemon

Bioactivity guided separation of Walsura trichostemon stem methanolic extract led to the isolation of four new dammarane (1-4) and two new apotirucallane triterpenoids (5-6), together with one limonoid (7), 11,25-dideacetyltrichostemonate, 12β, 20S, 24R-trihydroxydammar-25-en-3-one and 12β, 20S, 25-trihydroxydammar-23-en-3-one. Compounds 1-7 showed in vitro inhibitory activity on the proliferation of A549, human lung adenocarcinoma cell line.

Synthesis of nigranoic acid and manwuweizic acid derivatives as HDAC inhibitors and anti-inflammatory agents

As a successful anti-tumor drug target, the family of histone deacetylases (HDACs) is also a critical player in immune response, making the research of anti-inflammatory HDAC inhibitors an attractive new focus. In this report, triterpenoids nigranoic acid (NA) and manwuweizic acid (MA) were identified as HDAC inhibitors through docking-based virtual screening and enzymatic activity assay. A series of derivatives of NA and MA were synthesized and assessed for their biological effects. As a result, hydroxamic acid derivatives of NA and MA showed moderately increased activity for HDAC1/2/4/6 inhibition (the lowest IC₅₀ against HDAC1 is 1.14 μM), with no activity against HDAC8. In J774A.1 macrophage, compound 1-3, 13 and 17-19 demonstrated inhibitory activity against lactate dehydrogenase (LDH) and IL-1β production, without affecting cell viability. Compound 19 increased the histone acetylation level in J774A.1 cells, as well as inhibited IL-1β maturation and caspase-1 cleavage. These results indicated that compound 19 blocks the activation of NLRP3 inflammasome, probably related to HDAC inhibition. This work provided a natural scaffold for developing low-cytotoxic and anti-inflammatory HDAC inhibitors, as well as a class of tool molecules for studying the relationship between HDACs and NLRP3 activation.

Limonoids and other triterpenoids from Entandrophragma angolense

Four new compounds (1-4) were isolated from the stem bark of Entandrophragma angolense along with eleven known structures (5-15). The chemical structures were elucidated on the basis of spectroscopic and HRMS data, and the absolute configuration was established with the aid of electronic circular dichroism. Compound 5 displayed moderate cytotoxicity against MDA-MB-231, OVCAR3, MDA-MB-435, and HT29 cell lines, with IC₅₀ values ranging from 2.0-5.9 μM.

Antiophidic activity of the secondary metabolite lupeol isolated from Zanthoxylum monogynum

Previous studies have demonstrated the potential antiophidic activity of Zanthoxylum monogynum A.St.-Hil. a tree from the Rutaceae family native to South America. In this present contribution, we demonstrate the activity of the metabolite lupeol, a triterpenoid isolated from the stem bark of Z. monogynum against the harmful effects of the Bothrops alternatus venom. We investigated the antiophidic properties of lupeol, for this purpose, and use crude venom (Pb) incubated with lupeol in different concentrations, testing in vitro experiments and inoculated in mice for inhibitory evaluations in vivo. Besides, we tried to elucidate through the molecular dynamics the mechanism of action of lupeol with the bothropic thrombin-like toxin Jararacussin-I; the acidic phospholipase A₂ toxin BthA-I from Bothrops jararacussu and the metalloproteinase toxin BmooMP-I from Bothrops moojeni. In our results, we demonstrated the potential inhibitory effect upon coagulant, phospholipasic and myotoxic activities of the bothropic venom, previously incubated with lupeol. We found that lupeol triterpenoid was able to partially inhibit local and systemic damage caused by snake venom toxins. Our in silico results demonstrate that lupeol is capable of interacting and altering the activity of the thrombin-like toxin Jararacussin-I, and capable of interacting with the BthA-I acidic PLA₂, both toxins present in Bothrops snakes venom, thus demonstrating the pharmacological potential of this compound for the treatment of bothropic accidents.