Four new saponins from the root bark of Aralia elata

PgDDS Changes the Plant Growth of Transgenic Aralia elata and Improves the Production of Re and Rg3 in Its Leaves

Aralia elata (Miq.) Seem is a medicinal plant that shares a common pathway for the biosynthesis of triterpenoid saponins with Panax ginseng. Here, we transferred the dammarenediol-II synthase gene from P. ginseng (PgDDS; GenBank: AB122080.1) to A. elata. The growth of 2-year-old transgenic plants (L27; 9.63 cm) was significantly decreased compared with wild-type plants (WT; 74.97 cm), and the leaflet shapes and sizes of the transgenic plants differed from those of the WT plants. Based on a terpene metabolome analysis of leaf extracts from WT, L13, and L27 plants, a new structural skeleton for ursane-type triterpenoid saponins was identified. Six upregulated differentially accumulated metabolites (DAMs) were detected, and the average levels of Rg3 and Re in the leaves of the L27 plants were 42.64 and 386.81 μg/g, respectively, increased significantly compared with the WT plants (15.48 and 316.96 μg/g, respectively). Thus, the expression of PgDDS in A. elata improved its medicinal value.

Expression of PnSS Promotes Squalene and Oleanolic Acid (OA) Accumulation in Aralia elata via Methyl Jasmonate (MeJA) Induction

Aralia elata is an important herb due to the abundance of pentacyclic triterpenoid saponins whose important precursors are squalene and OA. Here, we found that MeJA treatment promoted both precursors accumulation, especially the latter, in transgenic A. elata, overexpressing a squalene synthase gene from Panax notoginseng(PnSS). In this study, Rhizobium-mediated transformation was used to express the PnSS gene. Gene expression analysis and high-performance liquid chromatography (HPLC) were used to identify the effect of MeJA on squalene and OA accumulation. The PnSS gene was isolated and expressed in A. elata. Transgenic lines showed a very high expression of the PnSS gene and farnesyl diphosphate synthase gene (AeFPS) and a slightly higher squalene content than the wild-type, but endogenous squalene synthase (AeSS), squalene epoxidase (AeSE), and β-amyrin synthase (Aeβ-AS) gene were decreased as well as OA content. Following one day of MeJA treatment, the expression levels of PeSS, AeSS, and AeSE genes increased significantly. On day 3, the maximum content of both products reached 17.34 and 0.70 mg·g^-1, which increased 1.39- and 4.90-fold than in the same lines without treatment. Transgenic lines expressing PnSS gene had a limited capability to promote squalene and OA accumulation. MeJA strongly activated their biosynthesis pathways, leading to enhance yield.

Natural Deep Eutectic Solvents for the Extraction of Triterpene Saponins from Aralia elata var. mandshurica (Rupr. & Maxim.) J. Wen

The roots of the medicinal plant Aralia elata are rich in biologically active natural products, with triterpene saponins constituting one of their major groups. These metabolites can be efficiently extracted by methanol and ethanol. Due to their low toxicity, natural deep eutectic solvents (NADES) were recently proposed as promising alternative extractants for the isolation of natural products from medicinal plants. However, although NADES-based extraction protocols are becoming common in routine phytochemical work, their application in the isolation of triterpene saponins has not yet been addressed. Therefore, here, we address the potential of NADES in the extraction of triterpene saponins from the roots of A. elata. For this purpose, the previously reported recoveries of Araliacea triterpene saponins in extraction experiments with seven different acid-based NADES were addressed by a targeted LC-MS-based quantitative approach for, to the best of our knowledge, the first time. Thereby, 20 triterpene saponins were annotated by their exact mass and characteristic fragmentation patterns in the total root material, root bark and root core of A. elata by RP-UHPLC-ESI-QqTOF-MS, with 9 of them being identified in the roots of this plant for the first time. Triterpene saponins were successfully extracted from all tested NADES, with the highest efficiency (both in terms of the numbers and recoveries of individual analytes) achieved using a 1:1 mixture of choline chloride and malic acid, as well as a 1:3 mixture of choline chloride and lactic acid. Thereby, for 13 metabolites, NADES were more efficient extractants in comparison with water and ethanol. Our results indicate that new, efficient NADES-based extraction protocols, giving access to high recoveries of triterpene saponins, might be efficiently employed in laboratory practice. Thus, our data open the prospect of replacing alcohols with NADES in the extraction of A. elata roots.

Traditional uses, phytochemistry, pharmacology, toxicity and quality control of medicinal genus Aralia: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Aralia, which belongs to Araliaceae family, is mainly distributed in Asia, such as China, Japan and South Korea. It has a long medicinal history and is widely used in the treatment of various diseases, such as hepatitis, rheumatoid arthritis, bruises, lumps and carbuncles.

AIM OF THE STUDY

The purpose of this review is to systematically evaluate the traditional uses, phytochemistry, pharmacology, toxicity and quality control of main medicinal plants of Aralia, discusses the application of ethnic medicine, modern scientific research and the relationship between them, and put forward some suggestions to promote the further development and utilization of Aralia.

MATERIALS AND METHODS

The relevant information on Aralia was collected through electronic databases (PubMed, Web of Science, Science Direct, Springer, CNKI and Wanfang), Chinese herbal classics, Ph.D. and M.Sc. dissertations, Chinese Pharmacopoeia. Plant names were verified by "The Plant List" (http://www.theplantlist.org). The literature cited in this review can be traced back to 1878 to 2021.

RESULTS

More than 290 chemical constituents have been isolated from the genus Aralia, including triterpenoid saponins, terpenoids, organic acids, flavonoids, polyacetylenes, phenylpropanoids and other constituents. Pharmacological studies have shown that the extracts and compounds of Aralia have a wide range of pharmacological activities, including anti-inflammation, analgesic, anti-tumor, liver protection, protection of cardiovascular and nervous system, regulating substance metabolism, antibacterial, antiviral and antioxidation.

CONCLUSIONS

The genus Aralia is not only an excellent traditional herbal medicine, but also a source of bioactive molecules with good application prospects. However, the structure-activity relationship, in vivo activity and action mechanism of its bioactive components need to be further studied. In addition, more toxicological and quality control studies are essential to evaluate the efficacy and safety of Aralia as medicine.

Identification and comparison of triterpene saponins in Aralia elata leaves and buds by the energy-resolved MSAll technique on a liquid chromatography/quadrupole time-of-flight mass spectrometry

In this study, we identify the triterpene saponins (TSs) extracted from the leaves and buds of Aralia elata (Miq.) Seems using ultra-performance liquid chromatography and positive ionization electrospray quadrupole time-of-flight mass spectrometry (UPLC-ESI⁺-QTOF). The energy-resolved MS^All (erMS^all) technique is applied in order to simultaneously collect the diverse precursors attributed to [M+H]⁺, [M + NH₄]⁺ and [M + Na]⁺ ions. A practical and effective erMS^all workflow is established to rapidly identify and compare the saponins in the analyzed samples. In total, 111 TSs of structure are estimated, including 44 new compounds that had not been identified previously in A. elata. Of the five aglycones detected in the samples, a sapogenin 3β, 16α, 23-trihydroxyoleana-11,13-dien-28-oic acid (A5) that is identified for the first time in A. elata leaves. Compared to the buds, the leaves number twice as many hederagenin-type (A2) compounds. Although the number of other aglycones does not vary significantly between the buds and the leaves, A5 compounds are exclusively detected in the latter. Moreover, the C-3 sugar chains of TSs in A. elata leaves are mainly neutral (e.g., Hex+Hex, Hex+Hex+Hex and Hex+Hex+Hex+Hex), whereas those of bud TS compounds are primarily acidic (e.g., Pen+HexA, Hex+HexA and Hex+Pen+HexA). Some of the identified TS compounds, e.g., 27, 28, 32, 46, 54, 57, 71 and 105 can be used as indices to evaluate the quality of the plant leaves and buds. Overall, this study is of great significance for the comparative study of triterpenoid saponins in the leaves and buds of Aralia elata.

Effects of Oleanane-Type Triterpene Saponins from the Leaves of Eleutherococcus senticosus in an Axonal Outgrowth Assay

An aqueous extract of Eleutherococcus senticosus leaves exerted a beneficial effect in restoring the neurite outgrowth from Aβ25-35-induced degeneration using an axonal density assay. Subsequent bioassay-guided fractionation afforded seven new oleanane-type triterpene saponins, ezoukoginosides A-G (1-7), along with nine known analogues. The structures of 1-7 were elucidated through chemical and spectroscopic approaches, and their effects on restoring the neurite outgrowth from Aβ25-35-induced degeneration were investigated. The results revealed that hydrophilic oleanane-type saponins substituted with a free carboxylic acid, hydroxy, or formyl group in the aglycone, especially when the oxidation occurred at C-29, not only restrained Aβ25-35-induced degeneration but also restored axonal outgrowth significantly. Compounds 2 (-COOH at C-29) and 3 (-CH2OH at C-29) showed the most potent bioactivity among the isolates.

Total aralosides of aralia elata (Miq) seem (TASAES) ameliorate nonalcoholic steatohepatitis by modulating IRE1α-mediated JNK and NF-κB pathways in ApoE-/- mice

ETHNOPHARMACOLOGICAL RELEVANCE

Total saponins of Aralia elata (Miq) Seem (TASAES) from the Chinese traditional herb Long ya Aralia chinensis L. is popularly used as a folk medicine to treat rheumatism, neurasthenia, diabetes, hepatitis and antivirus in Asian countries. However, there was poor study of TASAES on Non-alcoholic steatohepatitis (NASH), which is characterized by inflammatory responses and hepatocellular apoptosis exacerbating liver injury. This study aimed to clarify whether or not the anti-inflammatory and anti-apoptotic activities and protective mechanisms of the total aralosides of Aralia elata (Miq) Seem (TASAES) ameliorate NASH in a high-fat diet (HFD)-induced ApoE-/- mouse model.

MATERIAL AND METHODS

C57/BL6N and ApoE-/- mice were fed with HFD containing 0.3% cholesterol and 20% fat to induce NASH and then treated with TASAES (75,150mg/kg/day, i.g.) for 12 weeks. Liver tissue was procured for histological examination, real-time RT-PCR and Western blot analysis.

RESULTS

ASAES treatment groups exhibited lower serum alanine and aspartate aminotransferases than the NASH group. TASAES could also reduce hepatic steatosis, as revealed by histological changes. In addition, TASAES treatment groups showed lower protein and mRNA expression levels of pro-inflammatory cytokines, such as IL-6, MCP-1, and TNF-α than NASH group. Reduced TUNEL-positive cells were also found in TASAES treatment groups. Western blot and immunohistochemical results indicated that TASAES regulated apoptosis and inflammation-related protein expression. Furthermore, TASAES treatment significantly reduced the phosphorylation of IRE1α, JNK and IκB and the downstream activation of NF-κB p65 was also reduced.

CONCLUSION

These findings suggested that the ameliorative effects of TASASE in HFD-induced NASH were associated with the regulation of IRE1α-mediated JNK and NF-κB signal pathways, thereby protecting the liver against NASH.

Oleanane-type triterpene saponins from the bark of Aralia elata and their NF-κB inhibition and PPAR activation signal pathway

Two new oleanane-type triterpene saponins, tarasaponin IV (1) and elatoside L (2), and four known; stipuleanoside R(2) (3), kalopanax-saponin F (4), kalopanax-saponin F methylester (5), and elatoside D (6) were isolated from the bark of Aralia elata. Kalopanax-saponin F methyl ester was isolated from nature for the first time. Their chemical structures were elucidated using the chemical and physical methods as well as good agreement with those of reported in the literature. Oleanane-type triterpene saponins are the main component of A. elata. All compounds were investigated the anti-inflammatory activity. We measured their inhibition of NF-κB and activation of PPARs activities in HepG2 cells using luciferase reporter system. As results, compounds 2 and 4 were found to inhibit NF-κB activation stimulated by TNFα in a dose-dependent manner with IC(50) values of 4.1 and 9.5 μM, respectively, when compared with that of positive control, sulfasalazine (0.9 μM). Compounds 2 and 4 also inhibited TNFα-induced expression of iNOS and COX-2 mRNA. Furthermore, compounds 1-6 were evaluated PPAR activity using PPAR subtype transactivation assays. Among of them, compounds 4-6 significantly increased PPARγ transactivation. However, compounds 4-6 did not activate in any other PPAR subtypes.

Effect of five triterpenoid compounds isolated from root bark of Aralia elata on stimulus-induced superoxide generation, tyrosyl or serine/threonine phosphorylation and translocation of p47(phox), p67(phox), and rac to cell membrane in human neutrophils

Five triterpenoids; Congmuyanoside V, X, XI, XII, and XV (Cong. V, X, XI, XII, and XV) were isolated from the root bark of Aralia elata. The effect of these triterpenoids on stimulus-induced superoxide generation in human neutrophils was assayed by measuring the reduction of ferricytochrome c (cyt. c) using a dual-beam spectrophotometer. Translocation of p47(phox), p67(phox), and rac to the cell membrane and tyrosyl or serine/threonine phosphorylation of neutrophil proteins were investigated using specific monoclonal antibodies. The five triterpenoids used in the present experiment significantly suppressed N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced superoxide generation in concentration-dependent manner. Congmuyanoside V, XII, and XV also suppressed arachidonic acid (AA)-induced superoxide generation in high concentration. However, these triterpenoids showed no effect on phorbol 12-myristate 13-acetate (PMA)-induced superoxide generation. fMLP- and AA-induced tyrosyl phosphorylation and translocation of the cytosolic proteins p47(phox), p67(phox), and rac to the cell membrane were suppressed in parallel with the suppression of the stimulus-induced superoxide generation.

Two new saponins from the bud of Aralia elata (Miq.) Seem

Two new saponins, named congmuyanoside A and congmuyanoside B, have been isolated from the buds of Aralia elata (Miq.) Seem. Their structures have been determined on the basis of chemical and spectroscopic evidence.

Effects of Saponins from the Root Bark of Aralia elata on the Transport of Chondroitin Sulfate in Caco-2 Cell Monolayers and Rats

We investigated the intestinal absorption enhancing effect of the saponins from the root bark of Aralia elata (SRBAE) in Caco-2 cell monolayers and rats. SRBAE at concentrations of 0.04% and 0.08% (w/v) decreased the transepithelial electrical resistance (TEER) values and increased the paracellular uptake of chondroitin sulfates (CSs) having different molecular weights (MW 500, 4500, and 18000) in a dose-dependent manner. We also evaluated the cytotoxicity of SRBAE to determine its proper concentration as an absorption enhancer. MTT assay and trypan blue exclusion test indicated that the cytotoxicity of SRBAE at concentrations of 0.04% and 0.08% was negligible. CS (MW 18000) was orally administered with or without SRBAE to rats. The oral administration of SRBAE (250 mg/kg) in 1 h increased the intestinal absorption of CS, by 4.9-fold versus the control (CS alone). Histological examination of the gastrointestinal tissues showed that SRBAE did not cause any damage to tissues. In conclusion, our results suggest that SRBAE acts as an efficient absorption enhancer and makes it easier for hydrophilic molecules to penetrate the intestinal epithelium.

Saponins and Other Constituents from the Leaves of Aralia elata

A new triterpenoid saponin, together with five known saponins, were isolated from the nonpolar n-hexane fraction of the leaves of Aralia elata. The structure of the new saponin, durupcoside C, was elucidated as hederagenin 3-O-beta-D-glucopyranosyl(1-->3)-beta-D-glucopyranosyl(1-->3)-alpha-L-arabinopyranoside on the basis of spectroscopic analysis. The known saponins were characterized as 3-O-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranosyl hederagenin 28-O-beta-D-xylopyranosyl(1-->6)-beta-D-glucopyranosyl ester, hederagenin 3-O-beta-D-glucopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside, oleanolic acid 3-O-beta-D-glucopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside, hederagenin 3-O-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside (alpha-hederin), and hederagenin 3-O-beta-D-glucopyranosyl(1-->3)-alpha-L-arabinopyranoside (collinsonidin). In addition, two known lipids, Arisaema glyceride 3 and ceramide mixtures were also isolated and characterized. Collinsonidin and two known lipids were isolated for the first time from this plant.

Biological activities and distribution of plant saponins

Plant saponins are widely distributed amongst plants and have a wide range of biological properties. The more recent investigations and findings into their biological activities were summarized. Isolation studies of saponins were examined to determine which are the more commonly studied plant families and in which families saponins have been identified.

Five saponins from the root bark of Aralia elata

Five saponins, 3-O-[beta-D-glucopyranosyl (1-->2)-[beta-D-glucopyranosyl (1-->3)]-beta-D-glucopyranosyl]-oleanolic acid 28-O-beta-D-glucopyranosyl ester (aralia-saponin V), 3-O-[beta-D-glucopyranosyl (1-->2)-[beta-D-glucopyranosyl (1-->3)]-beta-D-glucopyranosyl]-echinocystic acid 28-O-beta-D-glucopyranosyl ester (aralia-saponin VI), 3-O-beta-D-glucopyranosyl (1-->2)-[beta-D-glucopyranosyl (1-->3)]-beta-D-glucopyranosyl]-hederagenin 28-O-beta-D-glucopyranosyl ester (aralia-saponin VII), 3-O-[beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->2)]-beta-D-glucopyranosyl]-caulophyllogenin 28-O-beta-D-glucopyranosyl ester (aralia-saponin VIII), 3-O-[beta-D-glucopyranosyl (1-->2)-[beta-D-glucopyranosyl(1-->3)]-alpha-L-arabinopyranosyl]-hederagenin 28-O-beta-D-glucopyranosyl ester (aralia-saponin IX), were isolated from the root bark of Aralia elata (Miq.) Seem., together with four known compounds. Their structures were determined on the basis of chemical and spectroscopic methods.