Rabdosiin

Phytochemical profiling and bioactivity assessment of underutilized Symphytum species in comparison with Symphytum officinale.[Pubmed:38252561]

J Sci Food Agric. 2024 May;104(7):3971-3981.

BACKGROUND: Symphytum (comfrey) genus, particularly Symphytum officinale, has been empirically used in folk medicine mainly for its potent anti-inflammatory properties. In an attempt to shed light on the valorization of less known taxa, the current study evaluated the metabolite profile and antioxidant and enzyme inhibitory effects of nine Symphytum species. RESULTS: Phenolic acids, flavonoids and pyrrolizidine alkaloids were the most representative compounds in all comfrey samples. Hierarchical cluster analysis revealed that, within the roots, S. grandiflorum was slightly different from S. ibericum, S. caucasicum and the remaining species. Within the aerial parts, S. caucasicum and S. asperum differed from the other samples. All Symphytum species showed good antioxidant and enzyme inhibitory activities, as evaluated in DPPH (up to 50.17 mg Trolox equivalents (TE) g(-1)), ABTS (up to 49.92 mg TE g(-1)), cupric reducing antioxidant capacity (CUPRAC, up to 92.93 mg TE g(-1)), ferric reducing antioxidant power (FRAP, up to 53.63 mg TE g(-1)), acetylcholinesterase (AChE, up to 0.52 mg galanthamine equivalents (GALAE) g(-1)), butyrylcholinesterase (BChE, up to 0.96 mg GALAE g(-1)), tyrosinase (up to 13.58 mg kojic acid equivalents g(-1)) and glucosidase (up to 0.28 mmol acarbose equivalents g(-1)) tests. Pearson correlation analysis revealed potential links between danshensu and ABTS/FRAP/CUPRAC, quercetin-O-hexoside and DPPH/CUPRAC, or Rabdosiin and anti-BChE activity. CONCLUSIONS: By assessing for the first time in a comparative manner the phytochemical-biological profile of a considerably high number of Symphytum samples, this study unveils the potential use of less common comfrey species as novel phytopharmaceutical or agricultural raw materials. (c) 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Influence of pyrrolizidine alkaloids depletion upon the biological activity of Symphytum officinale L. extracts.[Pubmed:36493995]

J Ethnopharmacol. 2023 Mar 1;303:116010.

ETHNOPHARMACOLOGICAL RELEVANCE: Comfrey (Symphytum officinale L., Boraginaceae) root preparations are used as both traditional remedies and therapeutic agents in treating pain and inflammation associated with joint, bone, and muscle ailments. Even though numerous phytochemicals contribute to the beneficial effects of comfrey, the presence of toxic pyrrolizidine alkaloids (PAs) overshadows its uses. AIM OF THE STUDY: In this work, different PA-/mucilage-depleted/undepleted comfrey root extracts were subjected to detailed phytochemical characterization and biological evaluation. MATERIALS AND METHODS: The phytochemical profiling was performed by LC-HRMS/MS. The quantification of PAs and major phenolic compounds was carried out by LC-MS/MS and LC-DAD. Antioxidant and enzyme inhibitory activity was determined by in vitro free radical scavenging, ion reducing, metal chelating, cholinesterase, tyrosinase, amylase, and glucosidase assays. Using an ex vivo model of LPS-stimulated neutrophils, their viability (as measured by flow cytometry) and the release of IL-1beta, IL-8, and TNF-alpha were determined (ELISA assay). RESULTS: 12 phenolic acids, six PAs, three organic acids, two fatty acids, and two sugars were identified in the obtained comfrey extracts. The PA-depleted materials contained PAs levels below 2 ppm, whereas the removal of mucilage increased the content of rosmarinic acid, globoidnan A, globoidnan B, and Rabdosiin. PA-depletion did not significantly affect the antioxidant potential. However, the radical scavenging and metal reducing properties were higher in the mucilage-depleted extracts. Neither PA-depletion nor mucilage-depletion had considerable effects on the in vitro inhibitory activity of cholinesterases, tyrosinase, amylase, and glucosidase or release of ex vivo pro-inflammatory cytokines (e.g., IL-1beta, IL-8, and TNF-alpha) in LPS-stimulated neutrophils. CONCLUSIONS: In light of their superior safety profiles, PA-depleted comfrey extracts can be utilized further in cosmetic and pharmaceutical products.

Echiumin E, an Aryl Dihydronaphthalene Lignan from the Australian Invasive Plant Paterson's Curse (Echium plantagineum).[Pubmed:36126331]

J Nat Prod. 2022 Oct 28;85(10):2474-2479.

A new aryl dihydronaphthalene lignan, echiumin E (1), and four known compounds, echiumin A, globoidnan A, (-)-Rabdosiin, and rosmarinic acid (2-5), were isolated from the Australian invasive plant Echium plantagineum (Paterson's curse) for the first time. Echiumin E (1) was characterized by 1D/2D NMR spectroscopy and MS spectrometry, with its absolute configuration assigned through comparison of experimental and TDDFT-calculated ECD data. Echiumin E (1) along with compounds 3-5 were screened in vitro against three cancer cell lines (SH-SY5Y, HeLa, and PC-3) and a prostate stromal (normal) cell line (WPMY-1) using a resazurin reduction assay. Echiumin E (1) was found to be active toward HeLa cells (IC(50) 0.21 muM).

Influence of the Post-Harvest Storage Time on the Multi-Biological Potential, Phenolic and Pyrrolizidine Alkaloid Content of Comfrey (Symphytum officinale L.) Roots Collected from Different European Regions.[Pubmed:34579358]

Plants (Basel). 2021 Sep 2;10(9):1825.

Comfrey (Symphytum officinale L.) roots are well-known bioactive ingredients included in various cosmeceutical and pharmaceutical preparations. In this study, the influence of the post-harvest storage on the chemico-biological potential of roots collected from different European regions and stored for up to six months was investigated. Total phenolic content (TPC) and total phenolic acid content (TPAC) were spectrophotometrically estimated, whereas the levels of individual phenolic and pyrrolizidine alkaloidal markers were determined by HPLC-DAD and HPLC-MS/MS, respectively. The changes in the biological potential was tracked via antioxidant (DPPH, ABTS, CUPRAC, and FRAP) and anti-enzymatic (cholinesterase, tyrosinase, glucosidase, and amylase) assays. TPC and TPAC varied from 6.48-16.57 mg GAE/g d.w. root and from 2.67-9.03 mg CAE/g, respectively. The concentration of the four phenolics (rosmarinic acid, globoidnan A, globoidnan B, Rabdosiin) and six pyrrolizidine alkaloids generally showed maximum values at 1-3 months, after which their levels significantly decreased. With respect to the bioassays, the samples showed a wide range of antioxidant and anti-enzymatic effects; however, a direct storage time-bioactivity relationship was not observed. Similar conclusions were also revealed by the multivariate and correlation analyses. Our study could improve the current knowledge of the shelf-life properties of comfrey-based products and enhance their industrial exploitation.

LC-HRMS/MS phytochemical profiling of Symphytum officinale L. and Anchusa ochroleuca M. Bieb. (Boraginaceae): Unveiling their multi-biological potential via an integrated approach.[Pubmed:34329923]

J Pharm Biomed Anal. 2021 Sep 10;204:114283.

This study was aimed at providing a comprehensive phytochemical characterization and multi-biological assessment of Symphytum officinale L., a medicinal plant with a noteworthy traditional use, and Anchusa ochroleuca M. Bieb., a Boraginaceae species from the Romanian flora. The dichloromethane, methanol and 65 % ethanol extracts obtained from the roots and aerial parts of both plants revealed the presence of numerous phenolic acids, oxygenated fatty acids, pyrrolizidine alkaloids (PAs) and flavonoids, as assessed by LC-HRMS/MS analysis. Consistent with their higher total phenolic content, the polar aerial part extracts of S. officinale and root extracts of A. ochroleuca showed the most significant antioxidant activities, as evaluated by DPPH (173.22-216.98 mg TE/g) and ABTS (219.41-311.97 mg TE/g) radical scavenging, CUPRAC (387.18-626.40 mg TE/g), FRAP (199.36-299.86 mg TE/g) and total antioxidant capacity (2.28-2.68 mmol TE/g). Furthermore, both plants exhibited good tyrosinase (19.11-43.89 mg KAE/g) and alpha-glucosidase (2.45-12.54 mmol ACAE/g) inhibitory effects. The orthogonal projections to latent structures discriminant analysis (OPLS-DA) allowed the objective differentiation between the roots and aerial parts of the two investigated species based on their phytochemical and biological profiles. The partial least square (PLS) analysis showed that several individual phenolic acids, such as danshensu, Rabdosiin and rosmarinic acid, significantly contributed to the antioxidant potential of both Boraginaceae species, whilst the relative levels of sucrose were positively correlated with the anti-enzymatic properties. Overall, S. officinale and A. ochroleuca could be regarded as rich sources of bioactive phytochemicals that could further lead to developing novel phyto-pharmaceutical commodities.

Globoidnan A, rabdosiin and globoidnan B as new phenolic markers in European-sourced comfrey (Symphytum officinale L.) root samples.[Pubmed:33015885]

Phytochem Anal. 2021 Jul;32(4):482-494.

INTRODUCTION: Symphytum officinale L. (comfrey, Boraginaceae) is a cultivated or spontaneously growing medicinal plant that is traditionally used for the treatment of bone fractures, hematomas, muscle pains and joint pains. A wide range of topical preparations and dried roots for ex tempore applications are marketed in European drug stores or pharmacies. OBJECTIVE: The aim of this study was to perform the qualitative and quantitative analysis of pyrrolizidine alkaloids (PAs) and phenolic compounds in the hydroethanolic extracts of 16 commercial comfrey root batches purchased from 12 different European countries. METHODS: Liquid chromatography hyphenated with high-resolution tandem mass spectrometry (LC-HRMS/MS) was used for the profiling of PAs and phenolic compounds, whereas LC-MS/MS and liquid chromatography with diode array detection (LC-DAD) were used for their quantification. RESULTS: 20 PAs (i.e. intermedine, lycopsamine, acetylintermedine, acetyllycopsamine, symphytine, symphytine-N-oxide), 17 phenolic compounds (i.e. caffeic and rosmarinic acids, Rabdosiin, globoidnan A, globoidnan B) and 9 nonphenolic compounds (sugars, organic and fatty acids) were fully or partly annotated in the analysed samples. In addition, the quantitative analyses revealed that globoidnan B, Rabdosiin and globoidnan A are new phenolic markers that can be used together with rosmarinic acid and PAs for the quality control of commercial comfrey root batches. CONCLUSIONS: This study brings new insights into the phytochemical complexity of S. officinale, revealing not only numerous toxic PAs, but also a significant number of valuable phenolic compounds that could contribute to the bioactivities of comfrey-based preparations.

Symphytum officinale L.: Liquid-liquid chromatography isolation of caffeic acid oligomers and evaluation of their influence on pro-inflammatory cytokine release in LPS-stimulated neutrophils.[Pubmed:32739565]

J Ethnopharmacol. 2020 Nov 15;262:113169.

ETHNOPHARMACOLOGICAL RELEVANCE: Symphytum officinale L. (comfrey, Boraginaceae) has been traditionally used for millennia in joint distortions, myalgia, bone fractures and hematomas. However, key activity-determining constituents and molecular mechanisms underlying its use have not been completely elucidated. AIM OF THE STUDY: The objective of this study was to isolate and identify the major compounds from a hydroethanolic root extract of S. officinale and evaluate their antioxidant potential, alongside their effect on the cytokine production of ex vivo stimulated neutrophils, thus providing scientific support for the traditional use of comfrey root. MATERIAL AND METHODS: Four caffeic acid oligomers were isolated from comfrey roots by liquid-liquid chromatography, their structures being established by MS and NMR analyses. In vitro antioxidant evaluation was performed by DPPH and ABTS assays. The cytotoxicity of isolated compounds was established by flow cytometry. The effect on cytokine release, such as interleukin (IL)-1beta, IL-8 and tumor necrosis factor alpha (TNF-alpha), in lipopolysaccharide (LPS)-stimulated neutrophils was determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: The main constituents found in comfrey root were represented by four caffeic acid oligomers, namely globoidnan B (1), Rabdosiin (2), rosmarinic acid (3) and globoidnan A (4). Rabdosiin, globoidnans A and B were isolated for the first time from S. officinale. In the in vitro antioxidant tests, compound 2 was the most active, with EC(50) values in DPPH and ABTS assays of 29.14 +/- 0.43 and 11.13 +/- 0.39, respectively. Neutrophils' viability over the tested concentration domain of 12.5-50 muM was not altered. At 50 muM, all compounds significantly inhibited IL-1beta release, with compound 3 (45.60% release vs. LPS stimulated neutrophils) being the most active, followed by compounds 1 (53.85%), 2 (69.89%) and 4 (60.68%). CONCLUSIONS: The four caffeic acid oligomers reported in S. officinale root may contribute to the overall anti-inflammatory activity for which comfrey preparations are used in traditional medicine.

LC-ESI-FT-MS(n) Metabolite Profiling of Symphytum officinale L. Roots Leads to Isolation of Comfreyn A, an Unusual Arylnaphthalene Lignan.[Pubmed:32630037]

Int J Mol Sci. 2020 Jun 30;21(13):4671.

Preparations of comfrey (Symphytum officinale L.) roots are used topically to reduce inflammation. Comfrey anti-inflammatory and analgesic properties have been proven in clinical studies. However, the bioactive compounds associated with these therapeutic activities are yet to be identified. An LC-ESI-Orbitrap-MS(n) metabolite profile of a hydroalcoholic extract of comfrey root guided the identification of 20 compounds, including a new arylnaphthalene lignan bearing a rare delta-lactone ring, named comfreyn A. Its structure was determined using extensive 2D NMR and ESI-MS experiments. Additionally, the occurrence of malaxinic acid, caffeic acid ethyl ester, along with the lignans ternifoliuslignan D, 3-carboxy-6,7-dihydroxy-1-(3',4'-dihydroxyphenyl) -naphthalene, globoidnan A and B, and Rabdosiin was reported in S. officinale for the first time. These results helped to redefine the metabolite profile of this medicinal plant. Finally, caffeic acid ethyl ester and comfreyn A were found to significantly inhibit E-selectin expression in IL-1beta stimulated human umbilical vein endothelial cells (HUVEC), with EC values of 64 and 50 microM, respectively.

Local anaesthetic potential, metabolic profiling, molecular docking and in silico ADME studies of Ocimum forskolei, family Lamiaceae.[Pubmed:32000524]

Nat Prod Res. 2021 Nov;35(22):4757-4763.

The present study aimed to detect the bioactive metabolites from Ocimum forskolei aerial parts which are responsible for the local anaesthetic activity of the ethyl acetate fraction. Following a bioassay-guided fractionation, twelve compounds were dereplicated from the ethyl acetate fraction which was the most potent one with a mean onset of action (1.43 +/- 0.07****) min compared to tetracaine as a positive control (1.37 +/- 0.07****) min. These compounds, along with seven other compounds (isolated by diverse chromatographic techniques) were subjected to a molecular docking study to declare the top scoring compounds predicted to be responsible for such activity. The results highlighted Rabdosiin and Apigenin-7-O-rutinoside as the main bioactive leaders of the local anaesthesia via forming multiple H- bonding with the sodium ion channels leading to their blockade and loss of pain sensation, which strongly supports the use of O. forskolei as a local anaesthetic agent.

Antiproliferative Activity of (-)-Rabdosiin Isolated from Ocimum sanctum L.[Pubmed:30870993]

Medicines (Basel). 2019 Mar 12;6(1):37.

Background: Ocimum sanctum L. (holy basil; Tulsi in Hindi) is an important medicinal plant, traditionally used in India. Methods: The phytochemical study of the nonpolar (dichloromethane 100%) and polar (methanol:water; 7:3) extracts yielded fourteen compounds. Compounds 6, 7, 9, 11, 12, and 13, along with the methanol:water extract were evaluated for their cytotoxicity against the human cancer cell lines MCF-7, SKBR3, and HCT-116, and normal peripheral blood mononuclear cells (PBMCs). Results: Five terpenoids, namely, ursolic acid (1), oleanolic acid (2), betulinic acid (3), stigmasterol (4), and beta-caryophyllene oxide (5); two lignans, i.e., (-)-Rabdosiin (6) and shimobashiric acid C (7); three flavonoids, luteolin (8), its 7-O-beta-D-glucuronide (9), apigenin 7-O-beta-D-glucuronide (10); and four phenolics, (E)-p-coumaroyl 4-O-beta-D-glucoside (11), 3-(3,4-dihydroxyphenyl) lactic acid (12), protocatechuic acid (13), and vanillic acid (14) were isolated. Compound 6 was the most cytotoxic against the human cancer lines assessed and showed very low cytotoxicity against PBMCs. Conclusions: Based on these results, the structure of compound 6 shows some promise as a selective anticancer drug scaffold.

A new caffeic acid tetramer from the Dracocephalum moldavica L.[Pubmed:28805461]

Nat Prod Res. 2018 Feb;32(3):370-373.

A new caffeic acid tetramer compound, named (+) methyl Rabdosiin (4), together with seven known caffeic acid multimers (1-3, 5-8) and one caffeic acid monomer (9), were isolated from the aerial parts of Dracocephalum moldavica L. The structures of these compounds were assigned on the basis of 1D and 2D NMR spectroscopic and mass spectrometry analyses. The protective effects of compounds 2-4 against hydrogen peroxide (H(2)O(2))-induced apoptosis were evaluated in primary cardiomyocytes of SD neonatal rats in vitro by the MTT method. Three compounds exhibited potent protective activities at 12.5 mug/mL.

Rosmarinic acid and its derivatives: biotechnology and applications.[Pubmed:21838541]

Crit Rev Biotechnol. 2012 Sep;32(3):203-17.

Rosmarinic acid (RA) is one of the first secondary metabolites produced in plant cell cultures in extremely high yields, up to 19% of the cell dry weight. More complex derivatives of RA, such as Rabdosiin and lithospermic acid B, later were also obtained in cell cultures at high yields. RA and its derivatives possess promising biological activities, such as improvement of cognitive performance, prevention of the development of Alzheimer's disease, cardioprotective effects, reduction of the severity of kidney diseases and cancer chemoprevention. The TNF-alpha-induced NF-kappaB signaling pathway has emerged as a central target for RA. Despite these impressive activities and high yields, the biotechnological production of these metabolites on an industrial scale has not progressed. We summarized data suggesting that external stimuli, the Ca(2+)-dependent NADPH oxidase pathway and processes of protein phosphorylation/dephosphorylation are involved in the regulation of biosynthesis of these substances in cultured plant cells. In spite of growing information about pathways regulating biosynthesis of RA and its derivatives in cultured plant cells, the exact mechanism of regulation remains unknown. We suggest that further progress in the biotechnology of RA and its derivatives can be achieved by using new high-throughput techniques.

Specific genes of cytochrome P450 monooxygenases are implicated in biosynthesis of caffeic acid metabolites in rolC-transgenic culture of Eritrichium sericeum.[Pubmed:19817693]

Biochemistry (Mosc). 2009 Aug;74(8):917-24.

Expression of rol agrobacterial oncogenes in plant cell cultures is known to result in activation of secondary metabolite biosynthesis. In the present work, we show that rolC can activate expression of key genes of secondary metabolism using the rolC-transgenic culture of Eritrichium sericeum producing caffeic acid metabolites (rosmarinic acid and Rabdosiin) as an example. Increased content of rosmarinic acid in the rolC-transformed callus culture resulted from transcriptional activation of members of the CYP98 family of plant cytochrome P450-containing monooxygenase genes. The rolC gene expression led to increased transcript abundance of the CYP98A3 subfamily members, which are closely related homologs of CYP98A6 of Lithospermum erythrorhizon and are known to be key genes in rosmarinic acid biosynthesis. In contrast, expression of other CYP genes, such as CYP98A1 and CYP98A2, which are not implicated in rosmarinic acid biosynthesis, was not activated in the rolC-transformed calluses. These results are indicative of selective effect of rolC on transcription of particular genes implicated in secondary metabolism.

High rabdosiin and rosmarinic acid production in Eritrichium sericeum callus cultures and the effect of the calli on masugi-nephritis in rats.[Pubmed:17485828]

Biosci Biotechnol Biochem. 2007 May;71(5):1286-93.

During an investigation of plant cell cultures that might be useful in the treatment of renal disorders, we established a vigorously-growing E-4 callus culture of Eritrichium sericeum that produced large amounts of caffeic acid metabolites, (-)-Rabdosiin (1.8% dry wt) and rosmarinic acid (4.6% dry wt). Elicitation of the calli by methyl jasmonate induced a 38% increase in total polyphenol production. The most efficient method of eliciting (-)-Rabdosiin biosynthesis was through the treatment of E-4 calli with cuprum glycerate, which induced an increase in (-)-Rabdosiin production of as much as 4.1% dry wt. Oral administration of E-4 callus biomass (100 mg/kg/d for 30 d) to rats with induced Masugi-nephritis caused an increase in diuresis and lowered creatinine excretion and proteinuria levels as compared with Masugi-nephritis untreated rats. While all of the Masugi-nephritis untreated rats began to suffer, near a quarter of the E-4 treated rats remained in good health. This result indicates that the E-4 culture has the potential to alleviate the symptoms associated with nephritis.

Caffeic acid metabolites from Eritrichium sericeum cell cultures.[Pubmed:15931584]

Planta Med. 2005 May;71(5):446-51.

Eritrichium sericeum (Boraginaceae) callus and root cultures were established and analyzed for caffeic acid metabolite (CAM) production. Two substances, (-)-Rabdosiin and rosmarinic acid, were identified as main CAMs produced by these cultures. The E. sericeum Er-1 root culture accumulated up to 1.5 % and 4.5 % DW of (-)-Rabdosiin and rosmarinic acid, respectively. Rabdosiin in the Lithospermum erythrorhizon callus cultures was produced exclusively as the (+)-enantiomer while in both Eritrichium cultures it occurred as the (-)-enantiomer. The E. sericeum Er-1 culture accumulated 3-fold higher levels of CAMs than the L. erythrorhizon culture. A new compound, named eritrichin, was isolated from the cultured E. sericeum cells. The structure of this compound was established as (2R)-3-(3,4-dihydroxyphenyl)-2-[4-(3,4-dihydroxyphenyl)-6,7-dihydroxy-2-naphthoyloxy]propanoic acid on the basis of spectral data.