A Geranylfarnesyl Diphosphate Synthase Provides the Precursor for Sesterterpenoid (C25) Formation in the Glandular Trichomes of the Mint Species Leucosceptrum canum.

Plant sesterterpenoids, an important class of terpenoids, are widely distributed in various plants, including food crops. However, little is known about their biosynthesis. Here, we cloned and functionally characterized a plant geranylfarnesyl diphosphate synthase (Lc-GFDPS), the enzyme producing the C25 prenyl diphosphate precursor to all sesterterpenoids, from the glandular trichomes of the woody plant Leucosceptrum canum. GFDPS catalyzed the formation of GFDP after expression in Escherichia coli. Overexpressing GFDPS in Arabidopsis thaliana also gave an extract catalyzing GFDP formation. GFDPS was strongly expressed in glandular trichomes, and its transcript profile was completely in accordance with the sesterterpenoid accumulation pattern. GFDPS is localized to the plastids, and inhibitor studies indicated its use of isoprenyl diphosphate substrates supplied by the 2-C-methyl-D-erythritol 4-phosphate pathway. Application of a jasmonate defense hormone induced GFDPS transcript and sesterterpenoid accumulation, while reducing feeding and growth of the generalist insect Spodoptera exigua, suggesting that these C25 terpenoids play a defensive role. Phylogenetic analysis suggested that GFDPS probably evolved from plant geranylgeranyl diphosphate synthase under the influence of positive selection. The isolation of GFDPS provides a model for investigating sesterterpenoid formation in other species and a tool for manipulating the formation of this group in plants and other organisms.

Directed production of aurantizolicin and new members based on a YM-216391 biosynthetic system.

Using a highly effective heterologous expression system, the YM-216391 (1) biosynthetic gene cluster was engineered to yield aurantizolicin (2) and the hybrid compound 3. Both of these compounds were isolated and fully structurally characterised and the bioactivity was evaluated. The results indicate that compound 3 exhibits significantly improved antitumor activity.

Pentacyclic triterpenoids as potential ACL inhibitors from the rare medicinal plant Semiliquidambar cathayensis.

An extensive phytochemical investigation on the rare medicinal plant Semiliquidambar cathayensis (family: Hamamelidaceae) led to the isolation of four new (1-4, named semiliquidacids A-D, respectively) and 25 related known pentacyclic triterpenoids. The new structures with absolute configurations were elucidated by spectroscopic methods, electronic circular dichroism (ECD) calculations, and single-crystal X-ray diffraction analysis. Compound 1 represents the first naturally occurring ursane-type triterpenoid featuring an uncommon C-25 formyl group. Compound 4 and oleanolic acid (13) exhibited remarkable inhibitory effects against the ATP-citrate lyase (ACL, an emerging drug target for hyperlipidemia and related metabolic disorders) with IC50 values of 6.5 and 11.9 µM, respectively. The molecular interaction and binding mode between the bioactive triterpenoids and ACL were elaborated by conducting a molecular docking study. Meanwhile, the chemotaxonomic significance of the isolated triterpenoids has been briefly discussed.

Defensive furofuran lignans localized to the oil cells of Neocinnamomum delavayi and their metabolism by a specialist insect.

Neocinnamomum delavayi (Lauraceae) leaves with abundant oil cells are seldom attacked by insects, but their chemical constituent and biological function remain obscure. Three furofuran lignans, including (+)-eudesmin (3), (+)-magnolin (4), and demethoxyaschantin (5), were identified to be the major specialized metabolites in the oil cells of N. delavayi leaves through laser microdissection coupled with NMR analysis. Compounds 3 and 4 exhibited obvious antifeedant activity against a generalist insect Spodoptera exigua, and their natural contents in the leaves could effectively defend against generalist insects. Intriguingly, three specific metabolites 9-11, the O-demethylation derivates of compounds 3-5, were identified from a native specialist insect Dindica polyphaenaria feeding with N. delavayi leaves, implying an adaptation mechanism of specialist insects to plant defensive compounds. The results revealed a chemical connection between plants and insects, which would contribute to our understanding of plant-insect interaction and insect management.

Chemical investigation of Buddleja officinalis leaves and localization of defensive triterpenoids to its glandular trichomes.

Buddleja officinalis is a traditional Chinese medicinal plant covered with glandular and non-glandular trichomes on leaves. Phytochemical investigation of its leaves led to the identification of one undescribed tetranorcycloartane 3-oxo-25,26,27,29-tetranorcycloartan-24-oic acid (1) and one first identified natural product tetranorcycloartane 3-oxo-25,26,27,29-tetranorcycloartan-24-oic methyl ester (2), along with an undescribed megastigmane glucoside (3) and 14 known constituents (4-17). Structures of undescribed chemicals were elucidated by comprehensive 1D and 2D NMR, MS and CD analysis. Further chemical investigation resulted in six triterpenoids (4-9) being localized to the trichomes of B. officinalis. The major trichome components cycloeucalenone (4) and 24-oxo-29-norcycloartan-3-one (5) showed potent antifeedant activity against a generalist insect cotton bollworm (Helicoverpa armigera), but no obvious activity against the specialist herbivore Hyphasis inconstans. Compounds 4 and 7 also displayed inhibitory effects on seed germination of Arabidopsis thaliana. In addition, 1 and 4 exhibited moderate antibacterial activity toward three gram-positive bacteria.

Heterologous characterization of mechercharmycin A biosynthesis reveals alternative insights into post-translational modifications for RiPPs.

Mechercharmycin A (MCM-A) is a marine natural product belonging to a family of polyazole cyclopeptides with remarkable bioactivities and unique structures. Identification, heterologous expression, and genetic characterizations of the MCM biosynthetic gene cluster in Bacillus subtilis revealed that it is a ribosomally synthesized and post-translationally modified peptide (RiPP) possessing complex with distinctive modifications. Based on this heterologous expression system, two MCM analogs with comparable antitumor activity are generated by engineering the biosynthetic pathway. Combinatorial co-production of a precursor peptide with different modifying enzymes in Escherichia coli identifies a different timing of modifications, showing that a tRNAGlu-dependent highly regioselective dehydration is the first modification step, followed by polyazole formation through heterocyclization and dehydrogenation in an N- to C-terminal direction. Therefore, a rational biosynthetic pathway of MCMs is proposed, which unveils a subfamily of azol(in)e-containing RiPPs and sets the stage for further investigations of the enzymatic mechanism and synthetic biology.

Combined iodine-125 seed strand, portal vein stent, transarterial chemoembolization, lenvatinib and anti-PD-1 antibodies therapy for hepatocellular carcinoma and Vp4 portal vein tumor thrombus: A propensity-score analysis.

Objective: To evaluate the safety and efficacy of interventional therapy (iodine-125[125I] seed strand and portal vein stent [PVS] implantation plus transarterial chemoembolization [TACE]) combined with systemic therapy (lenvatinib plus anti-PD-1 antibody) as first-line treatment for hepatocellular carcinoma (HCC) patients with Vp4 portal vein tumor thrombus (PVTT). Patients and methods: From December 2018 to October 2021, 87 HCC patients with Vp4 PVTT were included in this single-center retrospective study. Forty-seven patients underwent interventional therapy combined with lenvatinib and anti-PD-1 antibody (group A), while 40 cases underwent interventional therapy combined with lenvatinib only (group B). Overall response rate (ORR), stent occlusion rates (SOR), median overall survival (OS), median progression-free survival (PFS) and median stent patency time (SPT) were compared between the 2 groups. Results: The mean intended dose (r = 10 mm; z = 0; 240 days) was 64.9 ± 1.0 Gy and 64.5 ± 1.1 Gy in group A and B, respectively (p = 0.133). ORR and SOR were significantly different between group A and B (ORR, 55.3% vs 17.5%, p < 0.001; SOR, 12.8% vs 35.0%, p = 0.014). In the propensity-score matching (PSM) cohort, the median OS, median PFS and median SPT were significantly longer in group A compared with group B (32 PSM pairs; OS, 17.7 ± 1.7 vs 12.0 ± 0.8 months, p = 0.010; PFS, 17.0 ± 4.3 vs 8.0 ± 0.7 months, p < 0.001; SPT, not-reached vs 12.5 ± 1.1 months, p = 0.028). Conclusion: This interventional therapy combined with lenvatinib and anti-PD-1 antibody is safe and effective for HCC patients with Vp4 PVTT.

Sequence Type 5 (ST5) as a Possible Predictor of Bacterial Persistence in Adult Patients with Methicillin-Resistant Staphylococcus aureus Pneumonia Treated with Vancomycin.

Vancomycin remains the mainstay of treatment for methicillin-resistant Staphylococcus aureus (MRSA) pneumonia. This study assessed risk factors for vancomycin failure in 63 patients with MRSA pneumonia through detailed clinical, microbiological, pharmacokinetic/pharmacodynamic, and genetic analyses of prospective multicenter studies conducted from February 2012 to July 2018. Therapeutic drug monitoring was performed during vancomycin treatment, and the 24-h area under the curve (AUC0-24) was calculated. All baseline strains were collected for MIC determination, heterogeneous vancomycin-intermediate S. aureus (hVISA) screening, and biofilm determination. Whole-genome sequencing was performed on the isolates to analyze their molecular typing and virulence and adhesion genes. Clinical signs and symptoms improved in 44 patients (44/63, 69.8%), with vancomycin daily dose (P = 0.045), peak concentration (P = 0.020), and sdrC (P = 0.047) being significant factors. Isolates were eradicated in 51 patients (51/63, 81.0%), with vancomycin daily dose (P = 0.009), cardiovascular disease (P = 0.043), sequence type 5 (ST5; P = 0.017), tst (P = 0.050), and sec gene (P = 0.044) associated with bacteriological failure. Although the AUC0-24/MIC was higher in the groups with bacterial eradication, the difference was not statistically significant (P = 0.108). Multivariate analysis showed that no variables were associated with clinical efficacy; ST5 was a risk factor for bacterial persistence (adjusted odds ratio, 4.449; 95% confidence interval, 1.103 to 17.943; P = 0.036). ST5 strains had higher frequencies of the hVISA phenotype, biofilm expression, and presence of some adhesion and virulence genes such as fnbB, tst, and sec than non-ST5 strains. Our study suggests that ST5 is a possible predictor of bacterial persistence in MRSA pneumonia treated with vancomycin. IMPORTANCE Few studies have simultaneously examined the influence of clinical characteristics of patients with pneumonia, the vancomycin pharmacokinetic/pharmacodynamic (PK/PD) index, and the phenotypic and genetic characteristics of methicillin-resistant Staphylococcus aureus (MRSA) strains. We assessed risk factors for vancomycin failure in patients with MRSA pneumonia by analyzing these influences in a prospective multicenter study. Sequence type 5 (ST5) was a possible predictor of bacterial persistence in adult patients with MRSA pneumonia (adjusted odds ratio, 4.449). We found that this may be related to ST5 strains having higher levels of vancomycin heterogeneous resistance, biofilms, and the presence of adhesion and virulence genes such as fnbB, tst, and sec.

Corrigendum: Neutrophil-to-Lymphocyte and Platelet-to-Lymphocyte Ratios as Predictors of Outcomes in Patients With Unresectable Hepatocellular Carcinoma Undergoing Transarterial Chemoembolization Plus Sorafenib.

[This corrects the article DOI: 10.3389/fmolb.2021.624366.].

Neutrophil-to-Lymphocyte and Platelet-to-Lymphocyte Ratios as Predictors of Outcomes in Patients With Unresectable Hepatocellular Carcinoma Undergoing Transarterial Chemoembolization Plus Sorafenib.

Objectives: To investigate the predictive value of inflammatory biomarkers in patients with unresectable hepatocellular carcinoma (HCC) for outcomes following the combination treatment of transarterial chemoembolization (TACE) plus sorafenib. Materials and Methods: A total of 314 (270 male and 44 female) treatment-naïve patients with unresectable HCC treated by TACE plus sorafenib between January 2011 and December 2018 were enrolled in the retrospective study. The primary outcome was overall survival (OS). The secondary outcome was progression-free survival (PFS). Neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) were obtained within 3-7 days before the initial TACE and the median value of the NLR and PLR was considered as the cut-off value. Results: The median value of NLR and PLR was 2.42 and 100, respectively. The median OS and PFS of the entire cohort were 18.7 months (95% CI: 16.8-20.6) and 9.1 months (95% CI: 8.5-9.8), respectively. The low NLR and PLR group showed improved OS and PFS compared with the high NLR and PLR group [21.8 months (95% CI: 15.2-28.5) vs. 15.4 months (95% CI: 12.4-18.3), p < 0.0001; 21.6 months (95% CI: 15.8-27.5) vs. 14.9 months (95% CI: 11.9-17.8), p = 0.00027, respectively]. In addition, the low NLR and PLR group also provided a longer PFS than the high NLR and PLR group [10.4 months (95% CI: 8.9-12.0) vs. 8.1 months (95% CI: 7.1-9.2), p = 0.00022; 10.3 months (95% CI: 8.6-11.9) vs. 8.2 months (95% CI: 7.2-9.2), p < 0.0001, respectively]. High NLR and PLR at baseline were predictive factors of poor OS (p = 0.02 and p = 0.004) and PFS (p = 0.045 and p = 0.005). Conclusion: This study showed the prognostic value of quantitative inflammatory biomarkers in correlation with OS and PFS in unresectable HCC patients undergoing TACE plus sorafenib treatment.