Chemical investigation of the aerial parts of Astragalus lehmannianus Bunge (Leguminosae) led to the isolation and identification of a new cycloartane triterpene glycoside – lehmanniaside (2\'-O-acetyl-3-β-O-D-xylopyranosyl-3β,6α,16β,24α-tetrahydroxy-20,25-epoxycycloartane). Its structure was elucidated by means of spectroscopic analysis (HR-MS, 1D and 2D NMR). Bioassays showed that lehmanniaside exhibits weak anthelmintic, antifungal, and cytotoxic activities.

Infectious diseases caused by viruses like HIV and SARS-COV-2 (COVID-19) pose serious public health threats. In search for new antiviral small molecules from chemically underexplored Hypericum species, a previously undescribed atropisomeric C8-C8’ linked dimeric coumarin named bichromonol (1) was isolated from the stem bark of Hypericum roeperianum. The structure was elucidated by MS data and NMR spectroscopy. The absolute configuration at the biaryl axis was determined by comparing the experimental ECD spectrum with those calculated for the respective atropisomers. Bichromonol was tested in cell-based assays for cytotoxicity against MT-4 (CC50 ¼ 54 mM) cells and anti-HIV activity in infected MT-4 cells. It exhibits significant activity at EC50 ¼ 6.6–12.0 mM against HIV-1 wild type and its clinically relevant mutant strains. Especially, against the resistant variants A17 and EFVR, bichromonol is more effective than the commercial drug nevirapine and might thus have potential to serve as a new anti-HIV lead.

’Candidatus Phytoplasma mali’, is a bacterial pathogen associated with the so-called apple proliferation disease in Malus × domestica. The pathogen manipulates its host with a set of effector proteins, among them SAP11CaPm, which shares similarity to SAP11AYWB from ’Candidatus Phytoplasma asteris’. SAP11AYWB interacts and destabilizes the class II CIN transcription factors of Arabidopsis thaliana, namely AtTCP4 and AtTCP13 as well as the class II CYC/TB1 transcription factor AtTCP18, also known as BRANCHED1 being an important factor for shoot branching. It has been shown that SAP11CaPm interacts with the Malus × domestica orthologues of AtTCP4 (MdTCP25) and AtTCP13 (MdTCP24), but an interaction with MdTCP16, the orthologue of AtTCP18, has never been proven. The aim of this study was to investigate this potential interaction and close a knowledge gap regarding the function of SAP11CaPm. A Yeast two-hybrid test and Bimolecular Fluorescence Complementation in planta revealed that SAP11CaPm interacts with MdTCP16. MdTCP16 is known to play a role in the control of the seasonal growth of perennial plants and an increase of MdTCP16 gene expression has been detected in apple leaves in autumn. In addition to this, MdTCP16 is highly expressed during phytoplasma infection. Binding of MdTCP16 by SAP11CaPm might lead to the induction of shoot proliferation and early bud break, both of which are characteristic symptoms of apple proliferation disease.

An extensive phytochemical study of a foliose lichen from Indonesia, Parmelia cetrata, resulted in the successful isolation of 13 phenol and depside derivatives (1–13) including the previously unreported depsides 3′-hydroxyl-5′-pentylphenyl 2,4-dihydroxyl-6-methylbenzoate (7), 3′-hydroxyl-5′-propylphenyl 2,4-dihydroxyl-6-methylbenzoate (8) and 3′-hydroxyl-5′-methylphenyl 2-hydroxyl-4-methoxyl-6-propylbenzoate (9). The anti-infective activity of isolated compounds was evaluated against the gram-negative bacterium Aliivibrio fischeri and the nematode Caenorhabditis elegans. 2,4-Dihydroxyl-6-pentylbenzoate (5) and lecanoric acid (6) induced growth inhibition of A. fischeri with inhibition values of 49% and 100% at a concentration of 100 µM, respectively. The antibacterial activity might be due to their free carboxyl group. A phenolic group at C4 also contributed to the antimicrobial activity of the depsides as shown for compounds 7 and 8, which caused 89% and 96% growth inhibition at 100 µM, respectively. Lecanoric acid (6) in addition possesses significant anthelmintic effects causing 80% mortality of C. elegans at 100 µg/mL.

The chemical investigation of the root barks leaves and stem barks of Brucea antidysenterica J. F. Mill. (Simaroubaceae) led to the isolation of a new pregnane glycoside, named Bruceadysentoside A or 3-O-β-L-arabinopyranosyl-pregn-5-en-20-one (1) together with seventeen known compounds. Their structures were established from spectral data, mainly HRESIMS, 1 D and 2 D NMR and by comparison with literature data. Compounds 1, 2, 5, 6, 8, 10, 12 and 13 were tested in vitro for their effects on the viability of two different human cancer cell lines, namely prostate PC-3 adenocarcinoma cells and colorectal HT-29 adenocarcinoma cells. No substantial activities were recorded for 2, 10, 12 and 13 (up to 10 μM concentration). 1, 5 and 8 did not show strong anti-proliferative effects up to 100 μM, however, 6 exhibited a stronger anti-proliferative effect with IC50 values of ∼ 100 μM against PC-3 and ∼ 200 μM against HT-29.

A series of new 11-keto-β-boswellic acid were partially-synthesized by modifying the hydroxyl and carboxylic acid functional groups of ring A. The structures of the new analogs were confirmed by detailed spectral data analysis. Compounds 4, 5 and 9 exhibited potent anti-cancer results against two human tumor cancer cell lines having IC50 value of MCF-7 (breast) and LNCaP (prostate): 123.6, 9.6 and 88.94 μM and 9.6, 44.12 and 12.03 μM, respectively. Additionally, a maximum nuclear fragmentation was observed for 4 (78.44%) in AKBA treated cells after 24 hr followed by 5 and 9 with (74.25 and 66.9% respectively). This study suggests that the presence of hydrazone functionality (4 and 9) has effectively improved the potency of AKBA. Interestingly, compound 5 with a lost carboxylic acid group of ring A showed comparable potent activity. Highly selective AKBA requires further modification to improve its bioavailability and solubility inside the cancer cells.

In the current investigation, a series of heterocyclic derivatives of boswellic acids were prepared along with new monomers of 3-O-acetyl-11-keto-β-boswellic acid (AKBA, 1) 11-keto-β-boswellic acid (KBA, 2) and several new bis-AKBA and KBA homodimers and AKBA-KBA heterodimers. The effects of these compounds on the proliferation of different human cancer cell lines, viz., FaDu (pharynx carcinoma), A2780 (ovarian carcinoma), HT29 (colon adenocarcinoma), and A375 (malignant melanoma), have been evaluated. Thus, KBA homodimer 21 effectively inhibited the growth of FaDu, A2780, HT29, and A375 cells with EC50 values below 9 μM. In addition, compounds 7, 8, 11, 12, 15, 16, and 17 also exhibited cytotoxic effects for A2780, HT29, and A375 cancer cells. In particular, the pyrazine analog 8 was highly cytotoxic for A375 cancer cells with an EC50 value of 2.1 μM.

Atypical myopathy (AM) in horses is caused by ingestion of seeds of the Acer species (Sapindaceae family). Methylenecyclopropylacetyl-CoA (MCPA-CoA), derived from hypoglycin A (HGA), is currently the only active toxin in Acer pseudoplatanus or Acer negundo seeds related to AM outbreaks. However, seeds or arils of various Sapindaceae (e.g., ackee, lychee, mamoncillo, longan fruit) also contain methylenecyclopropylglycine (MCPG), which is a structural analogue of HGA that can cause hypoglycaemic encephalopathy in humans. The active poison formed from MCPG is methylenecyclopropylformyl-CoA (MCPF-CoA). MCPF-CoA and MCPA-CoA strongly inhibit enzymes that participate in β-oxidation and energy production from fat. The aim of our study was to investigate if MCPG is involved in Acer seed poisoning in horses. MCPG, as well as glycine and carnitine conjugates (MCPF-glycine, MCPF-carnitine), were quantified using high-performance liquid chromatography-tandem mass spectrometry of serum and urine from horses that had ingested Acer pseudoplatanus seeds and developed typical AM symptoms. The results were compared to those of healthy control horses. For comparison, HGA and its glycine and carnitine derivatives were also measured. Additionally, to assess the degree of enzyme inhibition of β-oxidation, several acyl glycines and acyl carnitines were included in the analysis. In addition to HGA and the specific toxic metabolites (MCPA-carnitine and MCPA-glycine), MCPG, MCPF-glycine and MCPF-carnitine were detected in the serum and urine of affected horses. Strong inhibition of β-oxidation was demonstrated by elevated concentrations of all acyl glycines and carnitines, but the highest correlations were observed between MCPF-carnitine and isobutyryl-carnitine (r = 0.93) as well as between MCPA- (and MCPF-) glycine and valeryl-glycine with r = 0.96 (and r = 0.87). As shown here, for biochemical analysis of atypical myopathy of horses, it is necessary to take MCPG and the corresponding metabolites into consideration.

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Glucosinolates, a group of sulfur-rich thioglucosides found in plants of the order Brassicales, have attracted a lot of interest as chemical defenses of plants and health promoting substances in human diet. They are accumulated separately from their hydrolyzing enzymes, myrosinases, within the intact plant, but undergo myrosinase-catalyzed hydrolysis upon tissue disruption. This results in various biologically active products, e.g. isothiocyanates, simple nitriles, epithionitriles, and organic thiocyanates. While formation of isothiocyanates proceeds by a spontaneous rearrangement of the glucosinolate aglucone, aglucone conversion to the other products involves specifier proteins under physiological conditions. Specifier proteins appear to act with high specificity, but their exact roles and the structural bases of their specificity are presently unknown. Previous research identified the motif EXXXDXXXH as potential iron binding site required for activity, but crystal structures of recombinant specifier proteins lacked the iron cofactor. Here, we provide experimental evidence for the presence of iron (most likely Fe2+) in purified recombinant thiocyanate-forming protein from Thlaspi arvense (TaTFP) using a Ferene S-based photometric assay as well as Inductively Coupled Plasma-Mass Spectrometry. Iron binding and activity depend on E266, D270, and H274 suggesting a direct interaction of Fe2+ with these residues. Furthermore, we demonstrate presence of iron in epithiospecifier protein and nitrile-specifier protein 3 from Arabidopsis thaliana (AtESP and AtNSP3). We also present a homology model of AtNSP3. In agreement with this model, iron binding and activity of AtNSP3 depend on E386, D390, and H394. The homology model further suggests that the active site of AtNSP3 imposes fewer restrictions to the glucosinolate aglucone conformation than that of TaTFP and AtESP due to its larger size. This may explain why AtNSP3 does not support epithionitrile or thiocyanate formation, which likely requires exact positioning of the aglucone thiolate relative to the side chain.