Cytotoxic iridal-type triterpenoids from Iris tectorum

Two new iridoid glycosides from the whole plant of Rehmania piasezkii

Two new iridoid glycosides, piasezkiiosides A (1) and B (2), were isolated from aqueous extract of the whole plant of Rehmannia piasezkii. Their structures were established from the spectroscopic data, chemical transformation, and X-ray diffraction analysis. Compound 1 exhibited weak hepatoprotective activity against APAP-induced HepG2 cell damage.

Ten cyclopentanoid monoterpenes from the whole plant of Rehmannia piasezkii maxim

Ten new cyclopentanoid monoterpenes (1-10) were isolated from the whole plant of Rehmannia piasezkii. The structures of these compounds were elucidated based on spectroscopic data analysis. In in-vitro assays, compounds 3, 7, and 9 exhibited weak hepatoprotective activities against APAP-induced HepG2 cell damage. Compound 9 exhibited protective effect on hapassocin carbon tetrachloride model.

Correlation between secondary metabolites of Iris confusa Sealy and Iris pseudacorus L. and their newly explored antiprotozoal potentials

BACKGROUND

In the last few decades, the use of plant extracts and their phytochemicals as candidates for the management of parasitic diseases has increased tremendously. Irises are aromatic and medicinal plants that have long been employed in the treatment of different infectious diseases by traditional healers in many cultures. This study aims to explore the potential of three common Iris species (I. confusa Sealy, I. pseudacorus L. and I. germanica L.) against infectious diseases. Their in vitro antiprotozoal potency against Plasmodium falciparum, Trypanosoma brucei brucei, T. b. rhodesiense, T. cruzi and Leishmania infantum beside their cytotoxicity on MRC-5 fibroblasts and primary peritoneal murine macrophages were examined.

METHODS

The secondary metabolites of the tested extracts were characterized by UPLC-HRMS/MS and Pearsons correlation was used to correlate them with the antiprotozoal activity.

RESULTS

Overall, the non-polar fractions (NPF) showed a significant antiprotozoal activity (score: sc 2 to 5) in contrast to the polar fractions (PF). I. confusa NPF was the most active extract against P. falciparum [IC50 of 1.08 μg/mL, selectivity index (S.I. 26.11) and sc 5] and L. infantum (IC50 of 12.7 μg/mL, S.I. 2.22 and sc 2). I. pseudacorus NPF was the most potent fraction against T. b. rhodesiense (IC50 of 8.17 μg/mL, S.I. 3.67 and sc 3). Monogalactosyldiacylglycerol glycolipid (18:3/18:3), triaceylglycerol (18:2/18:2/18:3), oleic acid, and triterpenoid irridals (spirioiridoconfal C and iso-iridobelamal A) were the top positively correlated metabolites with antiplasmodium and antileishmanial activities of I. confusa NPF. Tumulosic acid, ceramide sphingolipids, corosolic, maslinic, moreollic acids, pheophytin a, triaceylglycerols, mono- and digalactosyldiacylglycerols, phosphatidylglycerol (22:6/18:3), phosphatidylcholines (18:1/18:2), and triterpenoid irridal iso-iridobelamal A, were highly correlated to I. pseudacorus NPF anti- T. b. rhodesiense activity. The ADME study revealed proper drug likeness properties for certain highly corelated secondary metabolites.

CONCLUSION

This study is the sole map correlating I. confusa and I. pseudacorus secondary metabolites to their newly explored antiprotozoal activity.

Unusually cyclized triterpenoids: occurrence, biosynthesis and chemical synthesis

Covering: 2009 to 2021Biosynthetically, most of the syntheses of triterpenes follow the cascade cyclization and rearrangement of the acyclic precursors viz., squalene (S) and 2,3-oxidosqualene (OS), which lead to the very well known tetra- and pentacyclic triterpene skeletons. Aside from these, numerous other triterpenoid molecules are also reported from various natural sources and their structures are derived from "S" and "OS" via some unusual cyclization operations which are different from the usual tetra- and pentacyclic frameworks. Numerous compelling advances have been made and reported in the identification of these unusual cyclized mono-, di-, tri- and tetracyclic triterpenes between 2009 and 2021. Besides a dramatic increase in the newly isolated uncommon cyclized triterpenoids, substantial progress in the (bio)-synthesis of these triterpenes has been published along with significant progress in their biological effects. In this review, 180 new unusual cyclized triterpenoids together with their demonstrated biogenetic pathways, syntheses and biological effects will be categorized and discussed.

Cyclopentanoid monoterpenes from the whole plant of Rehmannia piasezkii maxim

Twelve undescribed cyclopentanoid monoterpenes, Jiopiasins A-K and 6-epi-rehmaglutin A, and 19 known compounds were isolated from the whole plant of Rehmannia piasezkii Maxim. The structures of these compounds, especially their absolute stereochemistry, were established by extensive spectroscopic analysis, various quantum chemical calculations, and/or X-ray diffraction analyses. Furthermore, in vitro assays, some compounds exhibited moderate hepatoprotective activities against N-acetyl-p-aminophenol (APAP)-induced HepG2 cell damage.

Four ionones and ionone glycosides from the whole plant of Rehmannia piasezkii

Four new ionones and ionone glycosides (1-4) were isolated from the whole plant of Rehmannia piasezkii Maxim. Their planar structures as well as absolute configuration were confirmed via spectroscopic analysis, ECD calculation, and X-ray crystallography. Compounds 1-4 were tested for their cytotoxicity against five human tumor cell lines and ability to inhibit LPS-activated NO production in the BV2 cell line.

Iridal-Type Triterpenoids Displaying Human Neutrophil Elastase Inhibition and Anti-Inflammatory Effects from Belamcanda chinensis

The aim of this study is to explore anti-inflammatory phytochemicals from B. chinensis based on the inhibition of pro-inflammatory enzyme, human neutrophil elastase (HNE) and anti-inflammatory activities in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage. Three stereoisomers of iridal-type triterpenoids (1–3) were isolated from the roots of B. chinensis and their stereochemistries were completely identified by NOESY spectra. These compounds were confirmed as reversible noncompetitive inhibitors against HNE with IC₅₀ values of 6.8–27.0 µM. The binding affinity experiment proved that iridal-type triterpenoids had only a single binding site to the HNE enzyme. Among them, isoiridogermanal (1) and iridobelamal A (2) displayed significant anti-inflammatory effects by suppressing the expressions of pro-inflammatory cytokines, such as iNOS, IL-1β, and TNF-α through the NF-κB pathway in LPS-stimulated RAW264.7 cells. This is the first report that iridal-type triterpenoids are considered responsible phytochemicals for anti-inflammatory effects of B. chinensis.

Identification of the metabolites produced following Iris tectorum Maxim oral administration and a network pharmacology-based analysis of their potential pharmacological properties

1. Iris tectorum Maxim is a traditional herbal medicine that has been used to treat cancer, abdominal distension, hepatic cirrhosis, and inflammatory diseases. How I. tectorum Maxim is metabolised and the mechanistic basis for its pharmacological activity remain to be defined.2. This study was designed to clarify the metabolism of I. tectorum Maxim and to explore the mechanistic basis for its pharmacological activity.3. In the present study, 51 metabolites were identified via mass spectrometry in samples of bile, urine, and faeces from Wistar rats. Metabolites were mainly formed by glucuronidation, sulphation, methylation, and amino acid conjugation.4. Tectoridin, tectorigenin, irigenin, iristectorigenin A, iristectorigenin B, and 6-hydroxygenistein were identified as potentially be bioactive candidate metabolites for which 36 putative targets and 90 interactions were detected through a network pharmacology analysis. Gene set enrichment analyses and compound-disease networks revealed the targets of these metabolites to regulate important proteins associated with cancer as well as cardiovascular, urogenital, and digestive system diseases.5. Molecular docking confirmed the interactions of these six candidate bioactive metabolites with carbonic anhydrase IV, VII, and XII.6. Overall, these data offer new insights into the metabolism and pharmacological activity of I. tectorum Maxim in vivo.

Identification and characterization of the chemical components of Iris tectorum Maxim. and evaluation of their nitric oxide inhibitory activity

RATIONALE

Iris tectorum Maxim. is a traditional medicinal herb that is commonly used to treat inflammatory conditions. The present study investigated the fragmentation patterns of isoflavone glycosides and their qualitative analysis. In addition, lipopolysaccharide (LPS)-induced RAW264.7 macrophages were used to evaluate the anti-inflammatory properties of I. tectorum Maxim. samples collected at different time points during the year.

METHODS

High-performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry (HPLC/QTOF-MS/MS) and HPLC with diode-array detection were employed for qualitative and quantitative analysis. The fragmentation patterns of the isoflavones were observed in negative electrospray ionization mode with collision-induced dissociation (CID). Their anti-inflammatory activity was assessed via nitric oxide (NO) production in LPS-treated RAW264.7 macrophages.

RESULTS

A total of 15 chemical components were observed and tentatively identified using HPLC/QTOF-MS/MS. At low collision energy, the relative abundances of the aglycone radical anions Y₀ ^- , [Y₀  - H]^-• , [Y₀  - CH₃ ]^-• and [Y₀  - H- CH₂ ]^-• were used for the structural characterization of tectoridin and tectorigenin-4'-O-β-D-glucoside. The radical ions [Y₀  - CH₃ ]^-• and [Y₀  - H - 2CH₃ ]^-• were also employed to differentiate between iristectorin A and iristectorin B based upon their high-energy CID spectra. Levels of 9.02 mg/g of tectoridin and 1.04 mg/g of tectorigenin were found in samples collected in June, which exhibited 69.7% NO inhibitory activity.

CONCLUSIONS

The characteristic fragmentation patterns enabled us to reliably identify isoflavone glycosides. The results of the quantitative determination and NO inhibitory activity offer insight into the optimal I. tectorum Maxim. harvesting time.

Triterpenoids

This review covers newly isolated triterpenoids that have been reported during 2015.

Iridal-Type Triterpenoids with a Cyclopentane Unit from the Rhizomes of Belamcanda chinensis

Ten new iridal-type triterpenoid derivatives, polycycloiridals K-T (1-10), with a cyclopentane moiety originating from the cyclization of the homofarnesyl side chain were isolated from the rhizomes of Belamcanda chinensis. Their structures were established by spectroscopic data, a single-crystal X-ray diffraction analysis, TDDFT quantum mechanical calculations, and chemical derivatization. Compounds 2 and 10 exhibited 33.4% and 32.9% inhibitory activities, respectively, against PTP1b (protein tyrosine phosphatase) at a concentration of 10 μM. A putative biosynthetic pathway is proposed.

Rearranged iridal-type triterpenoids from Iris tectorum

Three new iridal-type triterpenoids (1-3) featuring a rearranged homofarnesylside chain were isolated from the rhizomes of Iris tectorum. Compounds 2 and 3 were found to be a pair of epimers. Their structures were elucidated on the basis of comprehensive spectroscopic analysis. A possible biosynthetic pathway for them was postulated. Moreover, the mixture of compounds 2 and 3 exhibited moderate neuroprotective activity against serum deprivation-induced PC12 cell death.

New iridal-type triterpenoid derivatives with cytotoxic activities from Belamcanda chinensis

Eight new iridal-type triterpenoid derivatives, including two noriridals with ether bridge (1-2); two iridals lactone (3-4), four monocyclic iridals (5-8), together with five known iridals (9-14) were identified from the rhizome of Belamcanda chinensis. Their structures were elucidated on the basis of comprehensive spectroscopic methods and electronic circular dichroism (ECD) calculations. Bioassay results showed that belamcanoxide B (1) exhibited moderated cytotoxic activities against HCT-116 and MCF-7 cell lines with IC₅₀ values of 5.58 and 3.35 μM.

Iridal-type triterpenoids with anti-HBV activity from Iris confusa

Five new iridal-type triterpenoids, named as spirioiridoconfal A-C (1-3), isobelamcandal (4) and 17-hydroxyl-27-ene-iridal (5), along with one known compound (6) were isolated from the whole plant of Iris confusa. Their structures were determined by extensive spectroscopic analyses. Compounds 3 and 6 showed moderate activity against HBV DNA replication in vitro with the IC₅₀ value at 84.6 ± 24.9 (SI = 2.1) and 58.6 ± 6.1 (SI = 12.7) μM relatively.

Three new triterpenoids from Ganoderma theaecolum

Three new triterpenoids (1-3), together with four known triterpenoids (4-7), were isolated from the fruiting bodies of Ganoderma theaecolum. Their structures were elucidated on the basis of their spectroscopic data and chemical evidence. Compounds 4 and 6 exhibited antitumor activities against H460 cells with IC₅₀ values of 22.4 and 43.1 μM, respectively. And the cytotoxic activities of compounds 4 and 5 against MDA-MB-231 cancer cell lines were assayed with IC₅₀ values of 49.1 and 75.8 μM, respectively.

Apocynin derivatives from Iris tectorum

Phytochemical investigation of the rhizomes of Iris tectorum resulted in the isolation and characterization of three new apocynin derivatives, apocynin-4-O-β-D-(6'-O-syringyl)glucopyranoside (1), scrophenoside C-7-ethyl ether (2, 3), together with a new naturally occurring compound but known by synthesis, apocynin-4-O-β-D-xylopyranoside (4), and five known ones (5-9). Their structures were elucidated on the basis of spectroscopic data interpretation.

Polycycloiridals with a Cyclopentane Ring from Iris tectorum

Six new iridal-type triterpenoids containing an unprecedented cyclopentane ring, polycycloiridals E-J (1-6), were isolated from a large-scale re-extraction of Iris tectorum. A possible biosynthesis pathway is postulated. The known spirioiridotectal D (7) was also obtained in the current investigation, and its structure was unequivocally defined using X-ray diffraction data. Compound 7 suppressed LPS-activated NO production in the BV2 cell line with an IC₅₀ value of 0.54 μM.

Anti-inflammatory Constituents from the Aerial Parts of Iris minutiaurea

Phytochemical investigation of the methanol extract of the aerial parts of Iris minutiaurea (Iridaceae) using column chromatography led to the isolation of a new xanthone glycoside, 1-hydroxy-3,5-dimethoxy-xanthone-6- O-β-D-glucoside (1), together with one known flavonoid glycoside (2). The structure of this new compound was elucidated by analysis of spectroscopic, including ID (1H, 13C), 2D NMR (COSY, HMQC, HMBC), and high resolution fast atom bombardment mass spectrometric (HR-FAB-MS) data and enzyme hydrolysis. We found that compounds 1 and 2 significantly suppressed production of NO, and pro-inflammatory cytokine in LPS-induced RAW264.7 cells. These results suggest that compound 1 and 2 have anti-inflammatory activity related with production of TNF-α, IL-6, IL-β, and NO in macrophages, and then compound 1 were more efficient than compound 2 in lowering the level of proinflammatory cytokine.

Nine new compounds from the whole plants of Rehmannia chingii

Nine new compounds, together with 16 known analogs, were isolated from the whole plants of Rehmannia chingii. The structures of compounds 1-9 were elucidated on the basis of their spectroscopic data and chemical evidence. In addition, the new compounds were tested for their hepatoprotective activities against APAP-induced HepG2 cell damage and their ability to inhibit LPS-induced nitric oxide production in the murine microglia BV2 cell line. Compounds 2 and 5 exhibited pronounced hepatoprotective activities against APAP-induced HepG2 cell damage at a concentration of 10 μM, and compounds 4 and 9 showed moderate inhibitory activity against microglial inflammation factor with IC50 values of 3.51 and 7.11 μM, respectively.

Bioactive Iridoid Glycosides from the Whole Plants of Rehmannia chingii

Nine new iridoid glycosides, rehmachingiiosides A-I (1-9), together with 16 known analogues, were isolated from the whole plants of Rehmannia chingii. The structures of compounds 1-9 were elucidated on the basis of spectroscopic data analysis and from chemical evidence. Furthermore, in two vitro assays, compounds 5 and 10 showed an inhibitory effect on LPS-induced NO production with IC50 values of 2.5 and 7.3 μM, and compounds 4, 6, and 10-12 (when evaluated at 10 μM) exhibited evidence of hepatoprotective effects against APAP-induced HepG2 cell damage.

Polycycloiridals A-D, Four Iridal-Type Triterpenoids with an α-Terpineol Moiety from Iris tectorum

Polycycloiridals A-D, four novel iridals with an unprecedented α-terpineol moiety resulting from cyclization of the homofarnesylside chain, were isolated from the ethanol extract of rhizomes of Iris tectorum. Their structures were elucidated on the basis of comprehensive spectroscopic analysis. The absolute configuration of 1 was determined by the modified Mosher's method and comparison of experimental and calculated electronic circular dichroism (ECD) spectrum. A possible biosynthetic pathway was postulated.