An unexpected role of EasDaf: catalyzing the conversion of chanoclavine aldehyde to chanoclavine acid.

Ergot alkaloids (EAs) are a diverse group of indole alkaloids known for their complex structures, significant pharmacological effects, and toxicity to plants. The biosynthesis of these compounds begins with chanoclavine-I aldehyde (CC aldehyde, 2), an important intermediate produced by the enzyme EasDaf or its counterpart FgaDH from chanoclavine-I (CC, 1). However, how CC aldehyde 2 is converted to chanoclavine-I acid (CC acid, 3), first isolated from Ipomoea violacea several decades ago, is still unclear. In this study, we provide in vitro biochemical evidence showing that EasDaf not only converts CC 1 to CC aldehyde 2 but also directly transforms CC 1 into CC acid 3 through two sequential oxidations. Molecular docking and site-directed mutagenesis experiments confirmed the crucial role of two amino acids, Y166 and S153, within the active site, which suggests that Y166 acts as a general base for hydride transfer, while S153 facilitates proton transfer, thereby increasing the acidity of the reaction. KEY POINTS: • EAs possess complicated skeletons and are widely used in several clinical diseases • EasDaf belongs to the short-chain dehydrogenases/reductases (SDRs) and converted CC or CC aldehyde to CC acid • The catalytic mechanism of EasDaf for dehydrogenation was analyzed by molecular docking and site mutations.

Diterpenoids from Euphorbia peplus possessing cytotoxic and anti-inflammatory activities.

Phytochemical investigation into the medium polar fraction of the ethanol extract of Euphorbia peplus led to the identification of 32 diterpenoids with five structural types. Compounds 1-5 and 7-11 are reported for the first time, while the configuration of 6,7-epoxy group of 6 was revised to be ß-oriented. Compounds 1-5 feature a rare structural variation of the double bond at Δ1 migrating to Δ1(10) in the tigliane-type diterpenoid family. Biologically, compound 21 was found to be the only one to show moderate cytotoxic activity, associated with the presence of a benzoyloxy residue at C-16. Besides, compounds 4, 8, 12, 13, 16, and 19 show significant inhibitory activities against NO production induced by LPS in RAW264.7 macrophage cells, with IC50 values within 2-5 µM. Structure-activity relationship (SAR) analysis revealed that the ingenane-type diterpenoids have the best anti-inflammatory activity, and the esterification at 3-OH or 5-OH is crucial. Further biological researches demonstrated that 13, the predominant metabolite in this plant, exerts anti-inflammatory effects by blocking the activation of NF-κB and MAPK signaling pathways.

A combined strategy for the overproduction of complex ergot alkaloid agroclavine.

Microbial cell factories (MCFs) and cell-free systems (CFSs) are generally considered as two unrelated approaches for the biosynthesis of biomolecules. In the current study, two systems were combined together for the overproduction of agroclavine (AC), a structurally complex ergot alkaloid. The whole biosynthetic pathway for AC was split into the early pathway and the late pathway at the point of the FAD-linked oxidoreductase EasE, which was reconstituted in an MCF (Aspergillus nidulans) and a four-enzyme CFS, respectively. The final titer of AC of this combined system is 1209 mg/L, which is the highest one that has been reported so far, to the best of our knowledge. The development of such a combined route could potentially avoid the limitations of both MCF and CFS systems, and boost the production of complex ergot alkaloids with polycyclic ring systems.

Natural Enantiomers: Occurrence, Biogenesis and Biological Properties.

The knowledge that natural products (NPs) are potent and selective modulators of important biomacromolecules (e.g., DNA and proteins) has inspired some of the world's most successful pharmaceuticals and agrochemicals. Notwithstanding these successes and despite a growing number of reports on naturally occurring pairs of enantiomers, this area of NP science still remains largely unexplored, consistent with the adage "If you don't seek, you don't find". Statistically, a rapidly growing number of enantiomeric NPs have been reported in the last several years. The current review provides a comprehensive overview of recent records on natural enantiomers, with the aim of advancing awareness and providing a better understanding of the chemical diversity and biogenetic context, as well as the biological properties and therapeutic (drug discovery) potential, of enantiomeric NPs.

Bioactive Alpha-Pyrone and Phenolic Glucosides from the Marine-Derived Metarhizium sp. P2100.

Glycoside compounds have attracted great interest due to their remarkable and multifarious bioactivities. In this study, four hitherto unknown 4-methoxy-ß-D-glucosyl derivatives were obtained and identified from the marine-derived fungus Metarhizium sp. P2100, including three alpha-pyrone glycosides (1-3) and one phenolic glycoside (4). Their planar structures were elucidated by comprehensive spectroscopic analysis, including 1D/2D NMR and HRESIMS. The absolute configurations of 1-3 were determined by a single-crystal X-ray crystallographic experiment, a comparison of the experimental, and a calculated electronic circular dichroism (ECD) spectra, respectively. Compounds 2 and 3 are a pair of rare epimeric pyranoside glycosides at C-7 with a core of aglycone as 2H-pyrone. Compounds 1-4 exhibited weak anti-inflammatory activities. In particular, compounds 1-3 displayed inhibitory activities against α-amylase, showing a potential for the development of a new α-amylase inhibitor for controlling diabetes.

Diarylheptanoids with NO production inhibitory activity from Amomum kravanh.

Seven new diarylheptanoids, kravanhols C-I (1-7), along with two known analogues (8 and 9), were isolated from the fruits of Amomum kravanh. The structures of compounds 1-7 were elucidated by analysis of spectroscopic data, and the absolute configurations of selective ones were determined by time-dependent density functional theory (TD-DFT) based electronic circular dichroism (ECD) calculations. All compounds were evaluated for their inhibitory effects on the nitric oxide (NO) production induced by lipopolysaccharide (LPS) in murine RAW264.7 macrophage cells. Compounds 2, 5, 6 and 9 exhibited moderate inhibitory activity with IC50 values in the range of 17.4-26.5 µM, being more potent than the positive control dexamethasone (IC50 = 32.5 µM).

Structural characterization and biological evaluation of chemical constituents from Ilex cornuta.

One new ursane-type triterpenoid (1), one new ursane-type triterpenoid glycoside (2), and one new oleanane-type triterpenoid glycoside (3), along with 20 known compounds, were isolated from the leaves of Ilex cornuta. The structures of these natural products were elucidated on the basis of detailed spectroscopic analyses and chemical derivation. Our biological evaluation established that selective compounds showed moderate to significant antioxidant activities in the 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) methods.

Bioactive terpenoid constituents from Eclipta prostrata.

Chemical fractionation of the ethanolic extract of Eclipta prostrata yielded a series of unreported terpenoid constituents, including a rare 6/6/6/6-fused tetracyclic triterpenoid, a pentacyclic triterpenoid, two pentacyclic triterpenoid saponins, a diterpenoid and a sesquiterpenoid. Structures were assigned to these compounds on the basis of comprehensive spectroscopic analyses, with the absolute configurations of the tetracyclic triterpenoid, the diterpenoid and the sesquiterpenoid being determined via explanation of electronic circular dichroism data. Screening of these isolates in an array of bioassays revealed antibacterial, cytotoxic and α-glucosidase inhibitory activities for selective compounds. Of particular interest, the tetracyclic triterpenoid showed very strong inhibition against α-glucosidase with an IC50 of 0.82 ±â€¯0.18 µM, being 103-fold as active as the positive control acarbose.

New cinnamic acid-pregenolone hybrids as potential antiproliferative agents: Design, synthesis and biological evaluation.

A series of new cinnamic acid-pregenolone hybrids (5a-5o) was designed, synthesized and evaluated for their in vitro antiproliferative activity. Some of them showed potential antiproliferative activity and selectivity towards a panel of cancer cell lines, including A549, H157, HepG2, MCF-7, and HL-60. Among these analogs, compound 5f showed the most promising activity with IC50 values ranging from 3.2 to 6.8 µM, and it was taken as a model compound in the following antiproliferative mechanism study. In Hoechst 33258 staining assay, 5f-treated A549 cells displayed significant apoptosis characteristics. Flow cytometry analysis revealed that 5f showed the antiproliferative activity against A549 via G1 cell cycle arrest and inducing apoptosis. Western blotting analysis demonstrated that 5f enhanced apoptosis of A549 cells by down-regulating Bcl-2 and up-regulating Bax protein expression. The present study highlighted this series of cinnamic acid-pregenolone hybrids as a new antiproliferative lead prototype.

Bioactive sesquiterpenoids and sesquiterpenoid glucosides from the flowers of Inula japonica.

Three new sesquiterpenoids (1-3) and two new sesquiterpenoid glucosides (4 &5), along with 24 known analogues (6-29), were obtained from the flowers of Inula japonica. Structures of the new compounds were determined by interpretation of spectroscopic data, and their absolute configurations were established via comparison of experimental with computed ECD curves. All the isolates were tested in an in vitro cytotoxic assay against human A549, MCF-7 and MDA-MB-231 cancer cell lines, and selective ones displayed significant activity close to the positive control adriamycin. The new molecules 1-5 were also evaluated for their nitric oxide (NO) release inhibitory effect in murine macrophage RAW264.7 cells, with compound 1 showing comparable activity (IC50 16.2 ±â€¯0.8 µM) to the positive control dexamethasome. A preliminary mechanistic study of the effect of 8 toward A549 cells revealed that it could arrest cell cycle at G2/M phase and induce cell apoptosis in a dose-dependent manner.

New e:b-Friedo-Hopane Type Triterpenoids from Euphorbia peplus with Simiarendiol Possessing Significant Cytostatic Activity against HeLa Cells by Induction of Apoptosis and S/G2 Cell Cycle Arrest.

Seven rare e:b-friedo-hopane-type triterpenoids including four new (1-4) and three known (5-7) ones with 5 being first reported as a natural product, together with five other known triterpenoids (8-12), were isolated from the nonpolar fractions of the ethanolic extract of Euphorbia peplus. Structural assignments for these compounds were based on spectroscopic analyses and quantum chemical computation method. The structural variations for the C-21 isopropyl group, including dehydrogenation (1 and 3) and hydroxylation at C-22 (simiarendiol, 2), were the first cases among e:b-friedo-hopane-type triterpenoids. Simiarendiol (2) bearing a 22-OH showed significant cytostatic activity against HeLa and A549 human tumor cell lines with IC50 values of 3.93 ± 0.10 and 7.90 ± 0.31 µM, respectively. The DAPI staining and flow cytometric analysis revealed that simiarendiol (2) effectively induced cell apoptosis and arrested cell cycle at the S/G2 phases in a dose-dependent manner in HeLa cells.

Cuceolatins A-D: New Bioactive Diterpenoids from the Leaves of Cunninghamia lanceolata.

Four new diterpenoids named cuceolatins A-D, including three labdane-type (1-3) and one abietane-type (4) as well as three known labdane analogs (5-7), were reported from the leaves of Cunninghamia lanceolata. Structural assignments for these compounds were conducted by analyses of spectroscopic data, and their absolute configurations were determined by time-dependent density functional theory (TD-DFT) based electronic circular dichroism (ECD) calculations. Among them, the abietane-type diterpenoid (11-hydroxy-12-methoxyabieta-8,11,13-trien-3-one (4)) showed significant cytotoxicity against human MDA-MB-231, MCF-7, and HeLa tumor cell lines with IC50 measurements of 4.3, 2.8 and 4.5 µm, respectively, while the labdane-type diterpenoids with a 4α-carboxy group (1-3 and 5) exhibited moderate antibacterial activity towards Bacillus subtilis and Staphylococcus aureus with IC50 values all below 25 µm.

Absolute structure assignment of an iridoid-monoterpenoid indole alkaloid hybrid from Dipsacus asper.

Iridoid-monoterpenoid indole alkaloid hybrids (IMIAHs) represent a rare class of natural products reported from only several plants of Rubiaceae and Dipsacaceae families, while their structural assignments remain a very challenging work due to complexity and flexibility. In the current study, a new IMIAH (1) was isolated from the roots of Dipsacus asper and its structure with absolute configuration was unambiguously established by a combination of spectroscopic analyses, chemical degradation and ECD calculation. A new oleanane-type triterpenoid saponin (2) and 15 known co-metabolites were also obtained and structurally characterized. Our biological evaluations showed that compound 2 exhibited moderate inhibition against acetylcholine esterase (AChE) with an IC50 value of 15.8 ±â€¯0.56 µM, and compound 15 displayed potent cytotoxicity selectively against human A549 and H157 lung cancer cells with IC50 values of 6.94 ±â€¯0.24 and 9.06 ±â€¯0.12 µM, respectively.

Triterpenoids and triterpenoid saponins from Dipsacus asper and their cytotoxic and antibacterial activities.

Phytochemical investigation of the ethyl acetate soluble part, generated from the ethanol extract of the roots of Dipsacus asper, led to the separation and identification of three undescribed triterpenoids including one arborinane type, one ursane type and one oleanane type, two unreported oleanane type triterpenoid arabinoglycosides, and 18 known analogues. Structures of these compounds were determined by comprehensive spectroscopic analyses, with the absolute configurations of 25-acetoxy-28-dehydroxyrubiarbonone E and 2α,3ß-dihydroxy-23-norurs-4(24),11,13(18)-trien-28-oic acid being established by evaluation of their experimental and calculated ECD spectra. 25-Acetoxy-28-dehydroxyrubiarbonone E features an oxygenated C-25 that is the first case among arborinane type triterpenoids, while 2α,3ß,24-trihydroxy-23-norurs-12-en-28-oic acid incorporates a sp3 C-24 that is a rare structural feature of 23-norursane type triterpenoids. Of these isolates, 2',4'-O-diacetyl-3-O-α-l-arabinopyranosyl-23-hydroxyolea-12-en-28-oic acid and hederagonic acid exhibited moderate antibacterial activity against Staphylococcus aureus with IC50 values of 12.3 and 10.3 µM, respectively, while those with either a feruloyloxy group or an arabinosyl moiety at C-3 displayed potent cytotoxic activities against four tumor cell lines A549, H157, HepG2 and MCF-7.