El registro continuado de los efectos adversos mejora los resultados quirúrgicos / Continuous monitoring of adverse effects improves surgical outcomes

Antecedentes: Se ha debatido mucho sobre las ventajas e inconvenientes del uso de bases administrativas o de registros clínicos en los programas de mejora de la atención médica. El objetivo de este estudio ha sido revisar la implementación y los resultados de una política de evaluación continua, mediante un registro mantenido por profesionales de un Servicio de Cirugía. Material y métodos: Se incluyeron, de forma prospectiva, todos los pacientes ingresados en el servicio entre los años 2003 y 2022. Se anotaron todos los efectos adversos (EA) acaecidos durante el ingreso, la estancia en centros de convalecencia o en su domicilio durante un periodo mínimo de 30 días tras el alta. Resultados: De 60.125 registros, en 16.802 (27,9%) se registraron 24.846 EA. Hubo un aumento progresivo del número de EA registrados por ingreso (1,17 en 2003 vs. 1,93 en 2022) con una disminución de 26% de los registros con EA (35% en 2003 hasta 25,8% en 2022), de 57,5% en las reoperaciones (de 8 a 3,4%, respectivamente), y de 80% en la mortalidad (de 1,8 a 1%, respectivamente). Es de remarcar la reducción significativa de los EA graves, observada entre los años 2011 y el 2022 (56 vs. 15,6%). Conclusión: Un registro prospectivo de EA creado y mantenido por profesionales del servicio, junto con la presentación y discusión abierta y trasparente de los resultados, produce una mejora sostenida de los resultados en un servicio quirúrgico de un hospital universitario.(AU)

Background: There has been significant debate about the advantages and disadvantages of using administrative databases or clinical registries in healthcare improvement programs. The aim of this study was to review the implementation and outcomes of an accountability policy through a registry maintained by professionals of the surgical department.Materials and methods: All patients admitted to the department between 2003 and 2022 were prospectively included. All adverse events (AEs) occurring during the admission, convalescent care in facilities, or at home for a minimum period of 30 days after discharge were recorded. Results: Out of 60,125 records, 24,846 AEs were documented in 16,802 cases (27.9%). There was a progressive increase in the number of AEs recorded per admission (1.17 in 2003 vs. 1.93 in 2022) with a 26% decrease in entries with AEs (from 35% in 2003 to 25.8% in 2022), a 57.5% decrease in reoperations (from 8.0% to 3.4%, respectively), and an 80% decrease in mortality (from 1.8% to 1%, respectively). It is noteworthy that a significant reduction in severe AEs was observed between 2011 and 2022 (56% vs. 15.6%). Conclusion: A prospective registry of AEs created and maintained by health professionals, along with transparent presentation and discussion of the results, leads to sustained improvement in outcomes in a surgical department of a university hospital.(AU)

Continuous monitoring of adverse effects improves surgical outcomes.

BACKGROUND: There has been significant debate about the advantages and disadvantages of using administrative databases or clinical registry in healthcare improvement programs. The aim of this study was to review the implementation and outcomes of an accountability policy through a registry maintained by professionals of the surgical department. MATERIALS AND METHODS: All patients admitted to the department between 2003 and 2022 were prospectively included. All adverse events (AEs) occurring during the admission, convalescent care in facilities, or at home for a minimum period of 30 days after discharge were recorded. RESULTS: Out of 60,125 records, 24,846 AEs were documented in 16,802 cases (27.9%). There was a progressive increase in the number of AEs recorded per admission (1.17 in 2003 vs. 1.93 in 2022) with a 26% decrease in entries with AEs (from 35.0% in 2003 to 25.8% in 2022), a 57.5% decrease in reoperations (from 8.0% to 3.4%, respectively), and an 80% decrease in mortality (from 1.8% to 1.0%, respectively). It is noteworthy that a significant reduction in severe AEs was observed between 2011 and 2022 (56% vs. 15.6%). CONCLUSION: A prospective registry of AEs created and maintained by health professionals, along with transparent presentation and discussion of the results, leads to sustained improvement in outcomes in a surgical department of a university hospital.

Mass Balance and Absorption, Distribution, Metabolism, and Excretion Properties of Balcinrenone following Oral Administration in Combination with Intravenous Microtracer in Healthy Subjects.

An absorption, distribution, metabolism, and excretion study was performed to determine the basic pharmacokinetic parameters, mass balance, and metabolite profiles of balcinrenone, a mineralocorticoid receptor modulator, in humans. This open-label, single-center, nonrandomized study had a two-period design. In period 1, eight healthy male subjects were dosed with a microtracer intravenous infusion of [14C]balcinrenone shortly after receiving an oral dose of unlabeled balcinrenone in a capsule. Following a 7-day washout, the same group of subjects subsequently received an oral dose of [14C]balcinrenone as a suspension in period 2. Clearance and absolute bioavailability of balcinrenone were determined to be 14.2 l/h and 52%, respectively. Renal clearance was determined to be 5.4 l/h (>fu • glomerular filtration rate), indicating elimination via active tubular secretion, which was potentially mediated by P-glycoprotein 1 and/or organic anion transporter 3, according to in vitro transporter data. In total, 94.1% of the oral dose was recovered: 45.2% in the urine and 48.9% in the feces. Balcinrenone was primarily metabolized via oxidation, and in vitro data suggest that cytochrome P450 3A4 was the main enzyme responsible. Intact [14C]balcinrenone accounted for 55% of drug-related material in the plasma; four metabolites were identified, each representing <6% of the total plasma radioactivity. In conclusion, this two-period study has determined the basic pharmacokinetic parameters of balcinrenone in humans, including absolute bioavailability and disposition. No metabolites warranted further evaluation on account of their low representation, and any contribution to the pharmacodynamic response or potential drug-drug interactions was deemed negligible. SIGNIFICANCE STATEMENT: This study provides a detailed understanding of the pharmacokinetics, disposition, and metabolism of balcinrenone following oral and microtracer intravenous administration in humans. In vitro phenotyping and transporter data granted mechanistic insights into the absorption, distribution, metabolism, and excretion properties of balcinrenone. This knowledge will guide future nonclinical and clinical studies evaluating drug-drug interactions, organ dysfunction, and safety of metabolites.

Application of Accelerator Mass Spectrometry to Characterize the Mass Balance Recovery and Disposition of AZD4831, a Novel Myeloperoxidase Inhibitor, following Administration of an Oral Radiolabeled Microtracer Dose in Humans.

This study evaluated the mass balance and disposition of AZD4831, a novel myeloperoxidase inhibitor, in six healthy participants using a 14C-labeled microtracer coupled with analysis by accelerator mass spectrometry (AMS). A single oral dose of 10 mg 14C-AZD4831 (14.8 kBq) was administered as a solution, and 14C levels were quantified by AMS in blood, urine, and feces over 336 hours postdose. AZD4831 was rapidly absorbed, and AZD4831 plasma concentrations declined in a biphasic manner, with a long half-life of 52 hours. AZD4831 was eliminated via metabolism and renal excretion. An N-carbamoyl glucuronide metabolite of AZD4831 (M7), formed primarily via UGT1A1, was the predominant circulating metabolite. Presumably, M7 contributed to the long half-life of AZD4831 via biliary elimination and hydrolysis/enterohepatic recirculation of AZD4831. On average, ∼84% of administered 14C-AZD4831 was recovered by 336 hours postdose (urine, 51.2%; feces, 32.4%). Between 32%-44% of the dose was excreted as unchanged AZD4831 in urine, indicating renal elimination as the major excretory route. Only 9.7% of overall fecal recovery was recorded in the first 48 hours, with the remainder excreted over 48%-336 hours, suggesting that most fecal recovery was due to biliary elimination. Furthermore, only 6% of unchanged AZD4831 was recovered in feces. Overall, the fraction of the administered AZD4831 dose absorbed was high. 14C-AZD4831 was well tolerated. These findings contribute to increasing evidence that human absorption, distribution, metabolism, and excretion studies can be performed with acceptable mass balance recovery at therapeutically relevant doses and low radiolabel-specific activity using an AMS-14C microtracer approach. SIGNIFICANCE STATEMENT: In this study, the human absorption, distribution, metabolism, and excretion (hADME) of the novel myeloperoxidase inhibitor AZD4831 was assessed following oral administration. This included investigation of the disposition of M7, the N-carbamoyl glucuronide metabolite. Resolution of challenges highlighted in this study contributes to increasing evidence that hADME objectives can be achieved in a single study for compounds with therapeutically relevant doses and low radiolabel-specific activity by using an AMS-14C microtracer approach, thus reducing the need for preclinical radiolabeled studies.

Machine Learning Risk Prediction Model of 90-day Mortality After Gastrectomy for Cancer.

OBJECTIVE: To develop and validate a risk prediction model of 90-day mortality (90DM) using machine learning in a large multicenter cohort of patients undergoing gastric cancer resection with curative intent. BACKGROUND: The 90DM rate after gastrectomy for cancer is a quality of care indicator in surgical oncology. There is a lack of well-validated instruments for personalized prognosis of gastric cancer. METHODS: Consecutive patients with gastric adenocarcinoma who underwent potentially curative gastrectomy between 2014 and 2021 registered in the Spanish EURECCA Esophagogastric Cancer Registry database were included. The 90DM for all causes was the study outcome. Preoperative clinical characteristics were tested in four 90DM predictive models: Cross Validated Elastic regularized logistic regression method (cv-Enet), boosting linear regression (glmboost), random forest, and an ensemble model. Performance was evaluated using the area under the curve by 10-fold cross-validation. RESULTS: A total of 3182 and 260 patients from 39 institutions in 6 regions were included in the development and validation cohorts, respectively. The 90DM rate was 5.6% and 6.2%, respectively. The random forest model showed the best discrimination capacity with a validated area under the curve of 0.844 [95% confidence interval (CI): 0.841-0.848] as compared with cv-Enet (0.796, 95% CI: 0.784-0.808), glmboost (0.797, 95% CI: 0.785-0.809), and ensemble model (0.847, 95% CI: 0.836-0.858) in the development cohort. Similar discriminative capacity was observed in the validation cohort. CONCLUSIONS: A robust clinical model for predicting the risk of 90DM after surgery of gastric cancer was developed. Its use may aid patients and surgeons in making informed decisions.

Dose volume histogram constraints in patients with soft tissue sarcomas of the extremities and the superficial trunk treated with surgery and perioperative HDR brachytherapy.

BACKGROUND: Wound healing complications (WHC), osteoradionecrosis (ORN), and nerve damage (ND) are common adverse effects in adult patients with soft tissue sarcomas of the extremities and the superficial trunk treated with surgery and perioperative high dose rate brachytherapy (PHDRB) alone or combined with external beam radiotherapy (EBRT). RATIONALE: Analysis of the treatment factors contributing to these complications can potentially minimize their occurrence and severity. PATIENTS: A total of 169 patients enrolled in two parallel prospective studies were included in this analysis. Previously Unirradiated cases (Group 1; n = 139) were treated with surgical resection, 16-24 Gy of PHDRB and 45 Gy of EBRT. Adjuvant chemotherapy was given to selected patients with high-grade tumors. Previously irradiated cases (Group 2; n = 30) were treated with surgical resection and 32-40 Gy of PHDRB without further EBRT. METHODS: Patient factors, tumor factors, surgical factors, PHDRB factors and EBRT factors were analyzed using Cox univariate and multivariate analysis. RESULTS: In Previously Unirradiated cases, WHC, ORN and ND occurred in 38.8%, 5.0% and 19.4%. Multivariate analysis indicated that WHC increased with CTV size (p = 0.02) and CTV2cm3 Physical dose (p = 0.02). ORN increased with Bone2cm3 EQD2 ≥ 67 Gy(p = 0.01) and ND was more frequent in patients with TV100DVH-based dose (tissue volume encompassed by the 100% isodose) ≥ 84 Gy (p < 0.01). In Previously Irradiated cases, WHC, ORN and ND occurred in 63.3%, 3.3% and 23.3%. Multivariate analysis showed that WHC was more frequent in patients with Skin2cm3Lifetime EQD2 ≥ 84 Gy (p = 0.01) and ND was more frequent after CTVD90 Physical Doses ≥ 40 Gy (p < 0.01). CONCLUSIONS: WHC in Previously Unirradiated patients can be minimized by using a more conservative CTV definition together with a meticulous implant technique and planning aimed to minimize hyperdose CTV2cm3 areas. In Previously Irradiated patients WHC may be mimimized considering Lifetime EQD2 Skin2cm3 doses. ORN can be reduced by using the Bone2cm3 EQD2 constraint. ND occurs more frequently in patients with large tumors receiving high treated volume doses, but no specific constraints can be recommended due to the lack of peripheral nerve definition during brachytherapy planning.

Effect of Perioperative Blood Transfusions and Infectious Complications on Inflammatory Activation and Long-Term Survival Following Gastric Cancer Resection.

Background: The aim of this study was to evaluate the impact of perioperative blood transfusion and infectious complications on postoperative changes of inflammatory markers, as well as on disease-free survival (DFS) in patients undergoing curative gastric cancer resection. Methods: Multicenter cohort study in all patients undergoing gastric cancer resection with curative intent. Patients were classified into four groups based on their perioperative course: one, no blood transfusion and no infectious complication; two, blood transfusion; three, infectious complication; four, both transfusion and infectious complication. Neutrophil-to-lymphocyte ratio (NLR) was determined at diagnosis, immediately before surgery, and 10 days after surgery. A multivariate Cox regression model was used to analyze the relationship of perioperative group and dynamic changes of NLR with disease-free survival. Results: 282 patients were included, 181 in group one, 23 in group two, 55 in group three, and 23 in group four. Postoperative NLR changes showed progressive increase in the four groups. Univariate analysis showed that NLR change > 2.6 had a significant association with DFS (HR 1.55; 95% CI 1.06−2.26; p = 0.025), which was maintained in multivariate analysis (HR 1.67; 95% CI 1.14−2.46; p = 0.009). Perioperative classification was an independent predictor of DFS, with a progressive difference from group one: group two, HR 0.80 (95% CI: 0.40−1.61; p = 0.540); group three, HR 1.42 (95% CI: 0.88−2.30; p = 0.148), group four, HR 2.85 (95% CI: 1.64−4.95; p = 0.046). Conclusions: Combination of perioperative blood transfusion and infectious complications following gastric cancer surgery was related to greater NLR increase and poorer DFS. These findings suggest that perioperative blood transfusion and infectious complications may have a synergic effect creating a pro-inflammatory activation that favors tumor recurrence.

Textbook outcome and survival after gastric cancer resection with curative intent: A population-based analysis.

BACKGROUND: The concept of textbook outcome (TO) has been proposed for analyzing quality of surgical care. This study assessed the incidence of TO among patients undergoing curative gastric cancer resection, predictors for TO achievement, and the association of TO with survival. METHOD: All patients with gastric and gastroesophageal junction cancers undergoing curative gastrectomy between January 2014-December 2017 were identified from a population-based database (Spanish EURECCA Registry). TO included: macroscopically complete resection at the time of operation, R0 resection, ≥15 lymph nodes removed and examined, no serious postoperative complications (Clavien-Dindo ≥II), no re-intervention, hospital stay ≤14 days, no 30-day readmissions and no 90-day mortality. Logistic regression was used to assess the adjusted achievement of TO. Cox survival regression was used to compare conditional adjusted survival across groups. RESULTS: In total, 1293 patients were included, and TO was achieved in 541 patients (41.1%). Among the criteria, "macroscopically complete resection" had the highest compliance (96.5%) while "no serious complications" had the lowest compliance (63.7%). Age (OR 0.53 for the 65-74 years and OR 0.34 for the ≥75 years age group), Charlson comorbidity index ≥3 (OR 0.53, 95%CI 0.34-0.82), neoadjuvant chemoradiotherapy (OR 0.24, 95%CI 0.08-0.70), multivisceral resection (OR 0.55, 95%CI 0.33-0.91), and surgery performed in a community hospital (OR 0.65, CI95% 0.46-0.91) were independently associated with not achieving TO. TO was independently associated with conditional survival (HR 0.67, 95%CI 0.55-0.83). CONCLUSION: TO was achieved in 41.1% of patients who underwent gastric cancer resection with curative intent and was associated with longer survival.

Characterization of Clinical Absorption, Distribution, Metabolism, and Excretion and Pharmacokinetics of Velsecorat Using an Intravenous Microtracer Combined with an Inhaled Dose in Healthy Subjects.

This open-label, single-period study describes the human absorption, distribution, metabolism, excretion, and pharmacokinetics of velsecorat (AZD7594). Healthy subjects received inhaled velsecorat (non-radiolabeled; 720 µg) followed by intravenous infusion of carbon 14 (14C)-velsecorat (30 µg). Plasma, urine, and feces were collected up to 168 hours post-dose. Objectives included identification and quantification of velsecorat and its metabolites (i.e., drug-related material) in plasma and excreta, and determining the elimination pathways of velsecorat by measuring the rate and route of excretion, plasma half-life (t1/2), clearance, volume of distribution and mean recovery of radioactivity. On average, 76.0% of administered 14C dose was recovered by the end of the sampling period (urine = 24.4%; feces = 51.6%), with no unchanged compound recovered in excreta, suggesting that biliary excretion is the main elimination route. Compared with intravenous 14C-velsecorat, inhaled velsecorat had a longer t1/2 (27 versus 2 hours), confirming that plasma elimination is absorption-rate-limited from the lungs. Following intravenous administration, t1/2 of 14C-drug-related material was longer than for unchanged velsecorat, and 20% of the 14C plasma content was related to unchanged velsecorat. The geometric mean plasma clearance of velsecorat was high (70.7 l/h) and the geometric mean volume of distribution at steady state was 113 l. Velsecorat was substantially metabolized via O-dealkylation of the indazole ether followed by sulfate conjugation, forming the M1 metabolite, the major metabolite in plasma. There were 15 minor metabolites. Velsecorat was well tolerated, and these results support the progression of velsecorat to phase 3 studies. SIGNIFICANCE STATEMENT: This study describes the human pharmacokinetics and metabolism of velsecorat, a selective glucocorticoid receptor modulator, evaluated via co-administration of a radiolabeled intravenous microtracer dose and a non-radiolabeled inhaled dose. This study provides a comprehensive assessment of the disposition of velsecorat in humans. It also highlights a number of complexities associated with determining human absorption, distribution, metabolism, and excretion for velsecorat, related to the inhaled route, the high metabolic clearance, sequential metabolite formation and the low intravenous dose.

Long-term results of Perioperative High Dose Rate Brachytherapy (PHDRB) and external beam radiation in adult patients with soft tissue sarcomas of the extremities and the superficial trunk: Final results of a prospective controlled study.

BACKGROUND: To analyze toxicity, patterns of failure, and survival in 106 adult patients with soft tissue sarcomas of the extremity and the superficial trunk treated in a prospective controlled trial of combined Perioperative High Dose Rate Brachytherapy (PHDRB) and external beam radiotherapy (EBRT). METHODS: Patients were treated with surgical resection and 16 Gy or 24 Gy of PHDRB for negative or close/positive margins, respectively. EBRT (45 Gy) was added postoperatively. Adjuvant chemotherapy was given to selected patients with high-grade tumors. RESULTS: The median follow-up was 7.1 years (range, 0.6-16.0). Grade ≥3 adverse events were observed in 22 patients (20.8%), and grade ≥4 events in 14 patients (13.2%). No grade 5 events were noted. Multivariate analysis (p = 0.003) found that Grade ≥3 toxic events increased with increasing implant volume (TV100). Local control, locoregional control, and distant control rates at 5 and 10 years were 89% and 87%, 82% and 80% and 75% and 69%, respectively. Multivariate analysis (p = 0.024) found that positive margins correlated with decreased local control. Disease-free survival and overall survival rates at 5 and 10 years were 64% and 59% and 73% and 62%, respectively. In multivariate analysis, disease-free survival rates decreased with increasing tumor size (p = 0.0001) and inadequate margins (p = 0.024), and overall survival decreased with increasing tumor size (p = 0.001) and male gender (p = 0.039). CONCLUSIONS: The combination of conservative surgery, high-dose PHDRB, and EBRT produces adequate function and local control in the majority of patients with soft tissue sarcomas of the extremities and the superficial trunk, including a substantial percentage of cases with positive margins. Patients with larger tumors are at a higher risk of complications, treatment failure, and cancer-related death and require an individualized treatment approach.

In†Situ Cyclization of Native Proteins: Structure-Based Design of a Bicyclic Enzyme.

Increased tolerance of enzymes towards thermal and chemical stress is required for many applications and can be achieved by macrocyclization of the enzyme resulting in the stabilizing of its tertiary structure. Thus far, macrocyclization approaches utilize a very limited structural diversity, which complicates the design process. Herein, we report an approach that enables cyclization through the installation of modular crosslinks into native proteins composed entirely of proteinogenic amino acids. Our stabilization procedure involves the introduction of three surface-exposed cysteine residues, which are reacted with a triselectrophile, resulting in the in situ cyclization of the protein (INCYPRO). A bicyclic version of sortase A was designed that exhibits increased tolerance towards thermal as well as chemical denaturation, and proved to be efficient in protein labeling under denaturing conditions. In addition, we applied INCYPRO to the KIX domain, resulting in up to 24 °C increased thermal stability.

Perioperative high-dose-rate brachytherapy in locally advanced and recurrent gynecological cancer: Final results of a Phase II trial.

PURPOSE: To determine the long-term results of a Phase II trial of perioperative high-dose-rate brachytherapy (PHDRB) in primary advanced or recurrent gynecological cancer. METHODS AND MATERIALS: Fifty patients with locally advanced and recurrent gynecological cancer suitable for salvage surgery were included. Unirradiated patients (n = 25) received preoperative chemoradiation followed by surgery and PHDRB (16-24 Gy). Previously irradiated patients (n = 25) received surgery and PHDRB alone (32-40 Gy). RESULTS: Median followup was 11.5 years. Eight unirradiated patients (32%) developed Grade ≥3 toxic events including two fatal events. Local and locoregional control rates at 16 years were 87.3% and 78.9%, respectively. Sixteen-year disease-free and overall survival rates were 42.9% and 46.4%, respectively. Ten previously irradiated patients (40.0%) developed Grade ≥3 adverse events, including four fatal events. Local and locoregional control rates at 14 years were 59.6% and 42.6%, respectively. Fourteen-year disease-free and overall survival rates were 16.0% and 19.2%, respectively. CONCLUSIONS: PHDRB allows effective salvage of a subset of unfavorable gynecological tumors with high-risk surgical margins. Toxicity was unacceptable at the initial dose levels but deescalation resulted in the absence of severe toxicity without a negative impact on locoregional control. A substantial percentage of patients remain alive and controlled at >10 years including a few previously irradiated cases with positive margins.

Synthesis of complex head-to-side-chain cyclodepsipeptides.

Cyclodepsipeptides are cyclic peptides in which at least one amide link on the backbone is replaced with an ester link. These natural products present a high structural diversity that corresponds to a broad range of biological activities. Therefore, they are very promising pharmaceutical candidates. Most of the cyclodepsipeptides have been isolated from marine organisms, but they can also originate from terrestrial sources. Within the family of cyclodepsipeptides, 'head-to-side-chain' cyclodepsipeptides have, in addition to the macrocyclic core closed by the ester bond, an arm terminated with a polyketide moiety or a branched amino acid, which makes their synthesis a challenge. This protocol provides guidelines for the synthesis of 'head-to-side-chain cyclodepsipeptides' and includes-as an example-a detailed procedure for preparing pipecolidepsin A. Pipecolidepsin was chosen because it is a very complex 'head-to-side-chain cyclodepsipeptide' of marine origin that shows cytotoxicity in several human cancer cell lines. The procedure begins with the synthesis of the noncommercial protected amino acids (2R,3R,4R)-2-{[(9H-fluoren-9-yl)methoxy]carbonylamino}-3-hydroxy-4,5-dimethylhexanoic acid (Fmoc-AHDMHA-OH), Alloc-pipecolic-OH, (4R,5R)-5-((((9H-fluoren-9-yl)methoxy)carbonylamino)-4-oxo-4-(tritylamino)butyl)-2,2-dimethyl-1,3-dioxolane-4-carboxylic acid (Fmoc-DADHOHA(acetonide, Trt))-OH and the pseudodipeptide (2R,3R,4R)-3-hydroxy-2,4,6-trimethylheptanoic acid ((HTMHA)-D-Asp(OtBu)-OH). It details the assembly of the depsipeptidic skeleton using a fully solid-phase approach (typically on an amino polystyrene resin coupled to 3-(4-hydroxymethylphenoxy)propionic acid (AB linker)), including the key ester formation step. It concludes by describing the macrocyclization step performed on solid phase, and the global deprotection and cleavage of the cyclodepsipeptide from the resin using a trifluoroacetic acid-H2O-triisopropylsilane (TFA-H2O-TIS; 95:2.5:2.5) cocktail, as well as the final purification by semipreparative HPLC. The entire procedure takes ∼2 months to complete.

Structure-Based Design of Inhibitors of Protein-Protein Interactions: Mimicking Peptide Binding Epitopes.

Protein-protein interactions (PPIs) are involved at all levels of cellular organization, thus making the development of PPI inhibitors extremely valuable. The identification of selective inhibitors is challenging because of the shallow and extended nature of PPI interfaces. Inhibitors can be obtained by mimicking peptide binding epitopes in their bioactive conformation. For this purpose, several strategies have been evolved to enable a projection of side chain functionalities in analogy to peptide secondary structures, thereby yielding molecules that are generally referred to as peptidomimetics. Herein, we introduce a new classification of peptidomimetics (classes A-D) that enables a clear assignment of available approaches. Based on this classification, the Review summarizes strategies that have been applied for the structure-based design of PPI inhibitors through stabilizing or mimicking turns, ß-sheets, and helices.

Stellatolides, a new cyclodepsipeptide family from the sponge Ecionemia acervus: isolation, solid-phase total synthesis, and full structural assignment of stellatolide A.

The marine environment is a rich source of metabolites with potential therapeutic properties and applications for humans. Here we describe the first isolation, solid-phase total synthesis, and full structural assignment of a new class of cyclodepsipeptides from the Madagascan sponge Ecionemia acervus that shows in vitro cytotoxic activities at submicromolar concentrations. Seven structures belonging to a new family of compounds, given the general name stellatolides, were characterized. The sequence and stereochemistry of all the amino acids in these molecules were established by a combination of spectroscopic analysis, chemical degradation, and derivatization studies. Furthermore, the complete structure of stellatolide A was confirmed by an efficient solid-phase method for the first total synthesis and the full structural assignment of this molecule, including the asymmetric synthesis of the unique ß-hydroxy acid moiety (Z)-3-hydroxy-6,8-dimethylnon-4-enoic acid.

Rescuing biological activity from synthetic phakellistatin 19.

Phakellistatins is one of the families of Pro-rich cyclic peptides whose synthetic counterparts have revealed cytotoxicities that differ greatly from those displayed by their corresponding natural ones. This is also the case of the last member isolated from this family, phakellistatin19, an octacyclopeptide containing three Pro moieties and a high percentage of apolar residues. Exhaustive NMR studies on the synthetic and natural phakellistatin 19 have been performed in order to find a plausible explanation for this intriguing behavior. Moreover, taking advantage of phakellistatin's framework, analogues with different cis/trans geometry at the key prolyl peptide bonds were designed, covering a promising conformational space that could not be reached by the natural peptide. By introduction of proline surrogates (Ψ(Me,Me)pro residues) in phakellistatin 19, which effectively increases the percentage of cis conformation in the final peptides, this translates into enhanced biological activity, therefore "rescuing" an otherwise inactive cyclopeptide.

The first total synthesis of the cyclodepsipeptide pipecolidepsin A.

Pipecolidepsin A is a head-to-side-chain cyclodepsipeptide isolated from the marine sponge Homophymia lamellosa. This compound shows relevant cytotoxic activity in three human tumour cell lines and has unique structural features, with an abundance of non-proteinogenic residues, including several intriguing amino acids. Although the moieties present in the structure show high synthetic difficulty, the cornerstone is constituted by the unprecedented and highly hindered γ-branched ß-hydroxy-α-amino acid D-allo-(2R,3R,4R)-2-amino-3-hydroxy-4,5-dimethylhexanoic acid (AHDMHA) residue, placed at the branching ester position and surrounded by the four demanding residues L-(2S,3S,4R)-3,4-dimethylglutamine, (2R,3R,4S)-4,7-diamino-2,3-dihydroxy-7-oxoheptanoic acid, D-allo-Thr and L-pipecolic acid. Here we describe the first total synthesis of a D-allo-AHDMHA-containing peptide, pipecolidepsin A, thus allowing chemical structure validation of the natural product and providing a robust synthetic strategy to access other members of the relevant head-to-side-chain family in a straightforward manner.

"Head-to-side-chain" cyclodepsipeptides of marine origin.

Since the late 1980s, a large number of depsipeptides that contain a new topography, referred to as "head-to-side-chain" cyclodepsipeptides, have been isolated and characterized. These peptides present a unique structural arrangement that comprises a macrocyclic region closed through an ester bond between the C-terminus and a ß-hydroxyl group, and terminated with a polyketide moiety or a more simple branched aliphatic acid. This structural pattern, the presence of unique and complex residues, and relevant bioactivity are the main features shared by all the members of this new class of depsipeptides, which are reviewed herein.