DT-13 attenuates inflammation by inhibiting NLRP3-inflammasome related genes in RAW264.7 macrophages.

Plant derived saponins or other glycosides are widely used for their anti-inflammatory, antioxidant, and anti-viral properties in therapeutic medicine. In this study, we focus on understanding the function of the less known steroidal saponin from the roots of Liriope muscari L. H. Bailey - saponin C (also known as DT-13) in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages in comparison to the well-known saponin ginsenoside Rk1 and anti-inflammatory drug dexamethasone. We proved that DT-13 reduces LPS-induced inflammation by inhibiting nitric oxide (NO) production, interleukin-6 (IL-6) release, cycloxygenase-2 (COX-2), tumour necrosis factor-alpha (TNF-α) gene expression, and nuclear factor kappa-B (NFκB) translocation into the nucleus. It also inhibits the inflammasome component NOD-like receptor family pyrin domain containing protein 3 (NLRP3) regulating the inflammasome activation. This was supported by the significant inhibition of caspase-1 and interleukin-1 beta (IL-1ß) expression and release. This study demonstrates the anti-inflammatory effect of saponins on LPS-stimulated macrophages. For the first time, an in vitro study shows the attenuating effect of DT-13 on NLRP3-inflammasome activation. In comparison to the existing anti-inflammatory drug, dexamethasone, and triterpenoid saponin Rk1, DT-13 more efficiently inhibits inflammation in the applied cell culture model. Therefore, DT-13 may serve as a lead compound for the development of new more effective anti-inflammatory drugs with minimised side effects.

Four Steroidal Saponins from the Trunks of Dracaena cambodiana with Inhibition of NO Production in LPS Activated RAW264.7 Cells.

Dracaena cambodiana Pierre ex Gagnep. is well known as a medicinal plant and widely distributed in Vietnam. Phytochemical investigation on the trunks of D. cambodiana lead to the isolation of four undescribed compounds (1-4) together with seven known ones (5-11). Their structures were determined to be pennogenin-24-yl-O-ß-D-glucopyranoside (1), 17α-hydroxycambodianoside C (2), (25R)-27-hydroxypenogenin 3-O-α-L-rhamnopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-ß-D-glucopyranoside (3), (3ß,25R)-17α,22α-dihydroxy-furost-5-en-3-yl-O-α-L-rhamnopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-ß-D-glucopyranoside (4), dracagenin A (5), 1-O-ß-D-glucopyranosyl-2-hydroxy-4-allylbenzene (6), 1-O-α-L-rhamnopyranosyl-(1→6)-ß-D-glucopyranosyl-2-hydroxy-allylbenzene (7), 2-O-α-L-rhamnopyranosyl-(1→6)-ß-D-glucopyranosyl-1-hydroxy-allylbenzene (8), cinnamrutinoside A (9), icariside D1 (10), and seco-isolariciresinol 9-O-ß-glucopyranoside (11) by extensive spectroscopic investigation, HR-ESI-MS, 1D and 2D NMR spectra. The anti-inflammatory activity of the isolated compounds was evaluated on macrophages. Compounds 1-6 significantly inhibited nitric oxide production in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. Among them, compound 1 showed the best inhibitory activity with an IC50 value of 8.90±0.56 µM.

Four New Steroidal Saponins from the Roots of Dracaena cambodiana with NO Production Inhibition Activity in LPS Activated RAW 264.7 Cells.

Seven steroidal saponins including three new 16,23-cyclocholestanes (1-3) and one new pregane (4) were isolated from the roots of Dracaena cambodiana Pierre ex Gagnep. Their chemical structures were elucidated to be (23R,25R)-26-O-ß-D-glucopyranosyl-16,23-cyclocholesta-5,17(20)-dien-22-one-3ß,16α,26-triol-3-O-α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→3)]-ß-D-glucopyranoside (1), (23R,25R)-26-O-ß-D-glucopyranosyl-16,23-cyclocholesta-5,17,20(22)-trien-3ß,22,26-triol-3-O-α-L-rhamnopyranosyl-(1→3)-ß-D-glucopyranoside (2), (23R,25R)-16,23-cyclocholesta-5,16,20(22)-trien-3ß,22,26-triol-3-O-α-L-rhamnopyranosyl-(1→3)-ß-D-glucopyranoside (3), 3ß-[(O-α-L-rhamnopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-ß-D-gluco-pyranosyl)oxy]-pregna-5,17(20)-diene-16-one-20-carboxylic acid 4''''-O-ß-D-glucopyranosylisopentyl ester (4), cambodianoside A (5), diosbulbiside C (6), and diosbulbiside D (7), by IR, HR-ESI-MS, 1D and 2D NMR spectra. Compounds 1 and 4-7 inhibited nitric oxide (NO) production in lipopolysaccharide activated RAW 264.7 cells with IC50 values ranging from 19.03±1.84 to 67.92±3.81 µM, whereas compounds 2 and 3 were inactive with IC50 values over 100 µM.

Steroidal Saponins from Water Eggplant (Fruits of Solanum torvum) Exhibit Anti-Epileptic Activity against Pentylenetetrazole-Induced Seizure Model in Zebrafish.

The fruits of Solanum torvum Swartz, a wild relative of eggplant, are consumed as a wild vegetable in tropical regions of Africa, Asia, and South America. In traditional Chinese medicine, it is believed to have anti-inflammatory and sedative effects. In the Philippines, water decoction is used to treat hyperactivity disorder. Twenty-two steroidal saponins were isolated and purified from the fruits grown in Yunnan, China, including six new compounds: torvosides U-Z (1-6). During drying and cooking, the saponins may undergo transformation, resulting in small amounts of sapogenins. These transformations can include dehydration of hydroxyl groups at position C22, formation of double bonds at position 20, 22 or 22, 23, and even formation of peroxide products. Saponin compounds torvoside X (4), torvoside Y (5), torvoside A (7), and (25S)-3-oxo-5α-spirostan-6α-yl-O-ß-d-xylopyranoside (20), which are glycosylated at C-6, showed certain anti-epileptic activity in a pentylenetetrazole-induced zebrafish seizure model. No antiproliferative activity was detected when tested on the cancer cell line HepG2, and no hepatotoxic effect was noted on normal liver cell line LO2.

Deciphering the network of cholesterol biosynthesis in Paris polyphylla laid a base for efficient diosgenin production in plant chassis.

Cholesterol serves as a key precursor for many high-value chemicals such as plant-derived steroidal saponins and steroidal alkaloids, but a plant chassis for effective biosynthesis of high levels of cholesterol has not been established. Plant chassis have significant advantages over microbial chassis in terms of membrane protein expression, precursor supply, product tolerance, and regionalization synthesis. Here, using Agrobacterium tumefaciens-mediated transient expression technology, Nicotiana benthamiana, and a step-by-step screening approach, we identified nine enzymes (SSR1-3, SMO1-3, CPI-5, CYP51G, SMO2-2, C14-R-2, 8,7SI-4, C5-SD1, and 7-DR1-1) from the medicinal plant Paris polyphylla and established detailed biosynthetic routes from cycloartenol to cholesterol. Specfically, we optimized HMGR, a key gene of the mevalonate pathway, and co-expressed it with the PpOSC1 gene to achieve a high level of cycloartenol (28.79 mg/g dry weight, which is a sufficient amount of precursor for cholesterol biosynthesis) synthesis in the leaves of N. benthamiana. Subsequently, using a one-by-one elimination method we found that six of these enzymes (SSR1-3, SMO1-3, CPI-5, CYP51G, SMO2-2, and C5-SD1) were crucial for cholesterol production in N. benthamiana, and we establihed a high-efficiency cholesterol synthesis system with a yield of 5.63 mg/g dry weight. Using this strategy, we also discovered the biosynthetic metabolic network responsible for the synthesis of a common aglycon of steroidal saponin, diosgenin, using cholesterol as a substrate, obtaining a yield of 2.12 mg/g dry weight in N. benthamiana. Our study provides an effective strategy to characterize the metabolic pathways of medicinal plants that lack a system for in vivo functional verification, and also lays a foundation for the synthesis of active steroid saponins in plant chassis.

Steroidal Saponins from Solanum lyratum Thunb.

Four undescribed steroidal compounds along with twenty known compounds were isolated from n-butanol extracted fraction of the whole plants of Solanum lyratum Thunb (SLNF). Their structures were assigned based on analyses of the extensive spectroscopic data (including MS, 1D/2D NMR, and ECD) or comparisons of the NMR data with those reported. Among the knowns, three compounds were isolated from Solanum plants for the first time, while one compound was isolated from S. lyratum for the first time. In addition, the cytotoxicities of these isolates against human colon SW480 and hepatoma Hep3B cells were evaluated by a MTT assay. And, nine of them and SLNF exhibited significant activities against both SW480 and Hep3B cells, while twelve of them significantly inhibited the activities of SW480 cells. This study allows for the exploitation of chemical markers with potential significance in discrimination of Solanum plants, and uncovers the diverse steroidal constituents from S. lyratum dedicated for its future application in cancer treatment.

Two New Compounds from Allii Macrostemonis Bulbus and Their In Vitro Antioxidant Activities.

Two new compounds named 4,4'-bis(ß-D-glucopyranosyloxy)biphenyl (1) and spirostane-25(27)-en-2α,3ß-diol-3-O-ß-D-xylopyranosyl(1→3)-ß-D-glucopyranosyl(1→4)-ß-D-galactopyranoside (2) were isolated from n-butanol extraction part of 80% ethanol extract of Allii Macrostemonis Bulbus. Alongside these, ten known compounds (3-12) were also identified, including a flavonoid glycoside (3), seven steroids (4-10), a nucleoside (11), and a phenylpropanoid glycoside (12) were found. Notably, compounds 3-6 were isolated from this plant for the first time. The structures of all compounds were confirmed using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), 1D, and 2D NMR spectroscopy. Some of these compounds showed strong antioxidant activity, and compound 1 demonstrated the most potent reduction of ferric ions (Fe3+) with an IC50 value of 0.59 ± 0.18 mg/mL. Compounds 2 and 3 exhibited the highest scavenging activity against superoxide anion radicals (O2-·) with an IC50 value of 0.02 ± 0.01 mg/mL. Additionally, compound 3 displayed substantial scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with IC50 values of 0.21 ± 0.17 mg/mL and 0.02 ± 0.01 mg/mL, respectively. The discovery of these two new compounds is a reference for identifying Allii Macrostemonis Bulbus quality markers. Moreover, their exceptional antioxidant activity offers a promising avenue for uncovering novel natural antioxidants.

[Chemical constituents of Helleborus thibetanus].

The chemical constituents of Helleborus thibetanus were isolated and purified by silica gel column chromatography, Sephadex LH-20 gel column chromatography, and semi-preparative RP-HPLC, and the structures of all compounds were identified by modern spectrographic technology(MS, NMR). The MTT method was used to measure the cytotoxicity of compounds 1-8. Twelve compounds were isolated from the roots and rhizomes of H. thibetanus and were identified as(25R)-22ß,25-expoxy-26-[(O-ß-D-glucopyranosyl)oxy]-1ß,3ß-dihydroxyfurosta-5-en(1), ß-sitosterol myristate(2), ß-sitosterol lactate(3), ß-sitosterol 3-O-ß-D-glucopyrannoside(4), 4,6,8-trihydroxy-3,4-dihydronaphthalen-1(2H)-one(5), 1,3,5-trimethoxybenzene(6), 7,8-dimethylbenzo pteridine-2,4(1H,3H)-dione(7), 1H-indole-3-carboxylic acid(8), p-hydroxy cinnamic acid(9), lauric acid(10), n-butyl α-L-arabinofuranoside(11) and methyl-α-D-fructofuranoside(12), respectively. Among them, compound 1 is a new compound and named thibetanoside L; compounds 2, 5-8, 11 are first isolated from the family Ranunculaceae; compound 12 is isolated from the genus Helleborus for the first time. The results of MTT assay showed that the IC_(50) values of compounds 1-8 against HepG2 and HCT116 cells were greater than 100 µmol·L~(-1).

Steroidal saponins from Trillium tschonoskii rhizome repress cancer stemness and proliferation of intrahepatic cholangiocarcinoma.

A phytochemical study was carried out on the extract of Trillium tschonoskii rhizomes, resulting in the isolation of thirty-six steroidal glycosides (1-36). Their structures were established mainly by spectroscopic analyses as well as necessary chemical evidence, of which 1-25 were identified as new analogues. Herein, all the isolated analogues were screened for the cytotoxicity against intrahepatic cholangiocarcinoma (ICC) cell lines of HuCCT1 and RBE through tumor colony formation and CCK-8 survival analysis, and the results demonstrated that three compounds 9, 12, and 26 significantly repressed tumor colony and sphere formation in both cell lines, respectively. Furthermore, the three analogues possessed a remarkable inhibitory role of organoid formation established from hydrodynamic induced mouse primary intrahepatic cholangiocarcinoma. Moreover, the functional assays of flow cytometry analysis, cancer stemness related gene expression, and western blotting assays all indicated that compound 26 could significantly repress cancer stem markers. Taken together, these results demonstrate that steroidal glycosides derived from T. tschonoskii rhizomes could be potentially implicated in human ICC therapy.

Diosgenin suppresses COX-2 and mPGES-1 via GR and improves LPS-induced liver injury in mouse.

Using a wild yam (Dioscorea japonica), we previously found novel anti-inflammatory and anti-carcinogenic effects via the downregulation of cyclooxygenase (COX)-2 and microsomal prostaglandin E synthase (mPGES)-1. One of the substances in wild yam is a steroidal saponin, diosgenin. We demonstrated that diosgenin suppressed COX-2 in human non-small-cell lung carcinoma A549 cells via nuclear factor-kappa B (NF-κB) translocation and the effects were reversed by a glucocorticoid receptor antagonist, RU486. In lipopolysaccharide (LPS)-induced mouse liver injury, COX-2 and mPGES-1 were induced and localized in sinusoidal macrophages and endothelial cells; however, diosgenin administration significantly suppressed Ptgs2 and Ptges expression and decreased COX-2 and mPGES-1 immunopositive cells in the sinusoids. Multiple immunohistochemical analyses showed that diosgenin had an effect on COX-2 and mPGES-1, particularly in the macrophages. Thus, we showed that diosgenin downregulated COX-2 and mPGES-1 via the glucocorticoid receptor and suppressed COX-2 and mPGES-1 in the macrophages of LPS-induced acute mouse liver injury.

Steroidal saponins with cytotoxic effects from the rhizomes of Asparagus cochinchinensis.

In the ongoing research on potent antitumor agents from the rhizomes of Asparagus cochinchinensis, seven undescribed steroidal saponins asparagusoside A-G (1-7), along with twenty known ones (8-27), were isolated and elucidated via analyzing their 1D, 2D NMR, mass spectroscopic data and chemical methods. All isolated compounds were evaluated for their cytotoxic effects against human large cell lung carcinoma cells (NCI-H460) in vitro. Among them, compounds 7, 9 and 27 showed more significant antitumor activities than the positive control cisplatin (11.56 µM) with IC50 values of 1.39, 3.04, and 2.25 µM, respectively. Further research about asparagusoside G (7) showed G0/G1 arrest in NCI-H460 cell line cycle and induced cell death by apoptosis in a dose­dependent way.

New steroidal glycosides from the roots of Asparagus cochinchinensis.

Steroidal saponins were the main active constituents of the traditional medicinal herb Asparagus cochinchinensis. A phytochemical investigation of A. cochinchinensis roots led to the isolation of nine new steroidal glycosides (1-9) and seven known analogues (10-16). Their structures were established by spectroscopic analyses as well as necessary chemical evidence.

A cycloartenol synthase from the steroidal saponin biosynthesis pathway of Paris polyphylla.

Steroidal saponins named polyphyllin are the major active components of Paris polyphylla. Cycloartenol synthase (CAS) is a key enzyme that catalyzes the formation of the sterol scaffold. In this study, we cloned a putative CAS gene from Paris polyphylla. Heterologous expression in yeast indicated that PpCAS can convert 2,3-oxidosqualene into cycloartenol. qRT-PCR analysis showed that the expression of PpCAS was highest in leaves and lowest in roots. To our best knowledge, this is the first report of the functional characterization of cycloartenol synthase from Paris polyphylla, which lays the foundation for further analysis of the biosynthesis pathway of polyphyllins.[Formula: see text].

Genome-Wide Identification of CYP72A Gene Family and Expression Patterns Related to Jasmonic Acid Treatment and Steroidal Saponin Accumulation in Dioscorea zingiberensis.

Dioscorea zingiberensis is a medicinal herb containing a large amount of steroidal saponins, which are the major bioactive compounds and the primary storage form of diosgenin. The CYP72A gene family, belonging to cytochromes P450, exerts indispensable effects on the biosynthesis of numerous bioactive compounds. In this work, a total of 25 CYP72A genes were identified in D. zingiberensis and categorized into two groups according to the homology of protein sequences. The characteristics of their phylogenetic relationship, intron-exon organization, conserved motifs and cis-regulatory elements were performed by bioinformatics methods. The transcriptome data demonstrated that expression patterns of DzCYP72As varied by tissues. Moreover, qRT-PCR results displayed diverse expression profiles of DzCYP72As under different concentrations of jasmonic acid (JA). Likewise, eight metabolites in the biosynthesis pathway of steroidal saponins (four phytosterols, diosgenin, parvifloside, protodeltonin and dioscin) exhibited different contents under different concentrations of JA, and the content of total steroidal saponin was largest at the dose of 100 µmol/L of JA. The redundant analysis showed that 12 DzCYP72As had a strong correlation with specialized metabolites. Those genes were negatively correlated with stigmasterol and cholesterol but positively correlated with six other specialized metabolites. Among all DzCYP72As evaluated, DzCYP72A6, DzCYP72A16 and DzCYP72A17 contributed the most to the variation of specialized metabolites in the biosynthesis pathway of steroidal saponins. This study provides valuable information for further research on the biological functions related to steroidal saponin biosynthesis.

Lycoperoside H, a Tomato Seed Saponin, Improves Epidermal Dehydration by Increasing Ceramide in the Stratum Corneum and Steroidal Anti-Inflammatory Effect.

Tomatoes are widely consumed, however, studies on tomato seeds are limited. In this study, we isolated 11 compounds including saponins and flavonol glycosides from tomato seeds and evaluated their effects on epidermal hydration. Among the isolated compounds, tomato seed saponins (10 µM) significantly increased the mRNA expression of proteins related to epidermal hydration, including filaggrin, involucrin, and enzymes for ceramide synthesis, by 1.32- to 1.91-fold compared with the control in HaCaT cells. Tomato seed saponins (10 µM) also decreased transepidermal water loss by 7 to 13 g/m2·h in the reconstructed human epidermal keratinization (RHEK) models. Quantitative analysis of the ceramide content in the stratum corneum (SC) revealed that lycoperoside H (1-10 µM) is a promising candidate to stimulate ceramide synthesis via the upregulation of ceramide synthase-3, glucosylceramide synthase, and ß-glucocerebrosidase, which led to an increase in the total SC ceramides (approximately 1.5-fold) in concert with ceramide (NP) (approximately 2-fold) in the RHEK models. Evaluation of the anti-inflammatory and anti-allergic effects of lycoperoside H demonstrated that lycoperoside H is suggested to act as a partial agonist of the glucocorticoid receptor and exhibits anti-inflammatory effects (10 mg/kg in animal test). These findings indicate that lycoperoside H can improve epidermal dehydration and suppress inflammation by increasing SC ceramide and steroidal anti-inflammatory activity.

Qualitative and quantitative determination of steroidal saponins in Trillium govanianum by UHPLC-QTOF-MS/MS and UHPLC-ELSD.

INTRODUCTION: Trillium govanianum (Nag Chhatri and Teen Patra) is traditionally used for curing joint pains, wounds, and sexual disorders. Steroidal saponins are the main active components of this species. However, only a small amount of information is available about steroidal saponins of this plant. OBJECTIVE: To develop an ultra-high-performance liquid chromatography-quadrupole time of flight tandem mass spectrometry (UHPLC-QTOF-MS/MS) and ultra-high-performance liquid chromatography-evaporative light scattering detector (UHPLC-ELSD) methods for the qualitative and quantitative determination of steroidal saponins in T. govanianum. METHOD: The dried rhizomes of T. govanianum (100 mg) were extracted with ethanol-water (80:20, 10 mL) by ultrasonic treatment for 30 min at 40°C. The prepared sample was analysed by UHPLC-QTOF-MS/MS and UHPLC-ELSD for the qualitative and quantitative determination of steroidal saponins. RESULT: A total of 24 saponins were identified using UHPLC-QTOF-MS/MS; seven of them were characterised by comparing with standards. Furthermore, five saponins [govanoside B (2), protodioscin (6), pennogenin tetraglycosides (11), borassoside E (21) and borassoside D (24)] were quantified using UHPLC-ELSD method in different extracts and fractions of T. govanianum. The method showed good linearity (R2 ≥ 0.993), limit of detection (0.92-4.09 µg/mL), limit of quantification (3.1-13.5 µg/mL), precision [intra-day relative standard deviations (RSDs) < 4.3% and inter-day RSDs < 5.5%], and accuracy (84.0-110.3%). This is the first report on the quantification of 2, 6, 11, 21 and 24 in T. govanianum. CONCLUSION: The present study provides an efficient analytical method for the identification and quantification of steroidal saponins and will be helpful for the quality evaluation of T. govanianum.

Two new steroidal saponins from Neolamarckia cadamba.

Two new steroidal saponins, ß-sitosterol-3-O-α-l-glucopyranoside (3) and ß-sitosterol-3-O-ß-d-glucopyranosyl-(1→6)-ß-d-glucopyranoside (4), were isolated and identified from the bark of Neolamarckia cadamba, along with 13 known compounds. Their structures were established on the basis of spectral data.

Steroidal Glycosides from Allium tuberosum Seeds and Their Roles in Promoting Testosterone Production of Rat Leydig Cells.

A systematic phytochemical study on the components in the seeds of Allium tuberosum was performed, leading to the isolation of 27 steroidal glycosides (SGs 1-27). The structures of SGs were identified mainly by nuclear magnetic resonance and mass spectrometries as well as the necessary chemical evidence. In the SGs, 1-10 and 22-26 are new steroidal saponin analogues. An in vitro bioassay indicates that 1, 2, 7, 8, 10, 13-15, 20, 23, and 26 display promotional roles in testosterone production of rat Leydig cells with the EC50 values of 1.0 to 4.5 µM, respectively.

Development of an Oriental Medicine Discrimination Method through Analysis of Steroidal Saponins in Dioscorea nipponica Makino and Their Anti-Osteosarcoma Effects.

To prevent confusing Dioscorea nipponica (DN), an Oriental medicine, with Dioscorea quinquelobata (DQ) and Dioscorea septemloba (DS), a simple and accurate quantitative analysis method using HPLC combined with ultraviolet (UV) detection was developed and verified with UPLC-QTOF/MS through identification of five saponin glycosides: protodioscin (1), protogracillin (2), pseudoprotodioscin (3), dioscin (4), and gracillin (5). The newly developed analysis method showed sufficient reproducibility (<1.91%) and accuracy (92.1%-102.6%) and was able to identify DN based on the presence of compound 3 (13.821 ± 0.037 mg/mL) and the absence of 5. Compound 1, which is present in DN at a relatively high level (159.983 ± 0.064 mg/mL), was also an important marker for identification. Among the three species, DN showed the strongest activation of apoptotic signaling in osteosarcoma cells, while the four compounds detected in DN showed IC50 values of 6.43 (1), 10.61 (2), 10.48 (3), and 6.90 (4). In conclusion, the strong inhibitory effect of DN against osteosarcoma was confirmed to be associated with 1 and 4, which is also related to the quantitative results. Therefore, the results of this study might provide important information for quality control related to Oriental medicine.

Identification, characterization and expression analysis of genes involved in steroidal saponin biosynthesis in Dracaena cambodiana.

Dracaena cambodiana is a traditional medicinal plant used for producing dragon's blood. The plants and dragon's blood of D. cambodiana contain a rich variety of steroidal saponins. However, little is known about steroidal saponin biosynthesis and its regulation in D. cambodiana. Here, 122 genes encoding enzymes involved in steroidal saponin biosynthesis were identified based on transcriptome data, with 29 of them containing complete open reading frames (ORF). Transcript expression analysis revealed that several genes related to steroidal saponin biosynthesis showed distinct tissue-specific expression patterns; the expression levels of genes encoding the key enzymes involved in the biosynthesis and early modification of steroidal saponins were significantly down-regulated in the stems in response to the inducer of dragon's blood, exhibiting positive correlations with the content of steroidal saponins. These results provide insights on the steroidal saponins biosynthetic pathway and mechanisms underlying induced formation of dragon's blood in D. cambodiana.