MYC-Targeting Inhibitors Generated from a Stereodiversified Bicyclic Peptide Library.

Here, we present the second generation of our bicyclic peptide library (NTB), featuring a stereodiversified structure and a simplified construction strategy. We utilized a tandem ring-opening metathesis and ring-closing metathesis reaction (ROM-RCM) to cyclize the linear peptide library in a single step, representing the first reported instance of this reaction being applied to the preparation of macrocyclic peptides. Moreover, the resulting bicyclic peptide can be easily linearized for MS/MS sequencing with a one-step deallylation process. We employed this library to screen against the E363-R378 epitope of MYC and identified several MYC-targeting bicyclic peptides. Subsequent in vitro cell studies demonstrated that one candidate, NT-B2R, effectively suppressed MYC transcription activities and cell proliferation.

Aryliodonium Salt-Induced Regioselective Access to meta-Substituted Anilines by Arylation of Azoles.

A highly efficient aryliodonium salt-induced regioselective access to meta-substituted anilines by arylation of azoles has been developed under catalyst-free conditions. This efficient transformation provides a facile and scalable approach to a wide range of biologically active N-arylazoles with moderate to high yields. According to the control experiments, two plausible pathways, including a Michael pathway and a free radical coupling pathway, for the reaction were proposed.

Electrochemical Cross-Coupling between N-(4-Hydroxyphenyl)-sulfonamides and 2-Naphthols: Synthesis of 2,2'-Bis(arenol)s.

We herein present an electrochemical method for the dehydrogenative cross-coupling of N-(4-hydroxyphenyl)-sulfonamides and 2-naphthols. This transformation provides a direct and scalable approach to a wide range of C1-symmetric 2,2'-bis(arenol)s with moderate to high yields under mild conditions. Preliminary attempts with the asymmetric variant of this reaction were also performed with ≤55% ee for the synthesis of 2,2'-bis(arenol)s. Control experiments were conducted to propose a plausible mechanism for the reaction.

Novel reaction systems for catalytic synthesis of structured phospholipids.

Phospholipids are distinctive, adaptable molecules that are crucial to numerous biological systems. Additionally, their various architectures and amphiphilic characteristics support their unrivaled crucial functions in scientific and industrial applications. Due to their enormous potential for use in the fields of medicine, food, cosmetics, and health, structured phospholipids, which are modified phospholipids, have garnered increased attention. Traditional extraction methods, however, are pricy, resource-intensive, and low-yielding. The process of enzyme-catalyzed conversion is effective for producing several types of structured phospholipase. However, most frequently employed catalytic procedures involve biphasic systems with organic solvents, which have a relatively large mass transfer resistance and are susceptible to solvent residues and environmental effects due to the hydrophobic nature of phospholipids. Therefore, the adoption of innovative, successful, and environmentally friendly enzyme-catalyzed conversion systems provides a new development route in the field of structured phospholipids processing. Several innovative catalytic reaction systems are discussed in this mini-review, including aqueous-solid system, mixed micelle system, water-in-oil microemulsion system, Pickering emulsion system, novel solvent system, three-liquid-phase system, and supercritical carbon dioxide solvent system. However, there is still a glaring need for a thorough examination of these systems for the enzymatic synthesis of structural phospholipids. In terms of the materials utilized, applicability, benefits and drawbacks, and comparative effectiveness of each system, this research establishes further conditions for the system's selection. To create more effective biocatalytic processes, it is still important to build green biocatalytic processes with improved performance. KEY POINTS: • The latest catalytic systems of phospholipase D are thoroughly summarized. • The various systems are contrasted, and their traits are enumerated. • Different catalytic systems' areas of applicability and limitations are discussed.

Matrix metalloproteinase-2 delivery to extracellular vesicles produced by HPV-positive cervical cancer cells enhances metastasis via the Akt pathway.

Here, we aimed to analyze the effects of matrix metalloproteinase-2 (MMP-2) delivery to extracellular vesicles (EVs) secreted by human papillomavirus (HPV)-associated cervical cancer cells on human umbilical vein endothelial cell (HUVEC) angiogenesis. First, MMP-2 expression was compared among SiHa (HPV16), HeLa (HPV18), and C-33A (negative) cells. Then, EVs were isolated from these cells, and MMP-2 expression in the EVs was compared. SiHa and HeLa cells were transfected with MMP-2 or control siRNA. HUVECs were treated with EVs isolating from transfected cells. Migration and angiogenesis of HUVECs were measured, and p-Akt protein expression in HUVECs was detected. An Akt inhibitor or activator was used to analyze the effect of MMP-2 delivery to EVs on the migration of HUVECs. The SiHa-induced xenograft tumors were treated with 2 µg of EVs every 3 d for a total of 27 d. Tumor growth, and the expression levels of p-Akt, MMP-2, and vascular endothelial growth factor (VEGF) were observed in the tumors. The results showed that MMP-2 expression was higher in SiHa- and HeLa-derived EVs than that in the C-33A-derived EVs. Interference with MMP-2 suppressed the invasion of SiHa and HeLa cells. The migration and angiogenesis of HUVECs were enhanced by MMP-2 delivery to EVs secreted by SiHa and HeLa cells through regulation of the Akt pathway. The growth of xenograft tumors was accelerated by EVs secreted by SiHa cell with differential MMP-2 expression. Our results indicate the delivered MMP-2 in EVs acts as a messenger between HPV-associated cancer cells and HUVECs.

Knowledge, attitudes, practices and associated factors regarding high output stoma of ileostomy among colorectal surgical nurses: a multicentre cross-sectional study.

PURPOSE: High output stoma(HOS) is one of the most common complications after ileostomy, leading to fluid and electrolyte disturbances and renal dysfunction, and increasing the risk of readmission. Routine health education for HOS should be provided, and nurses, as the primary educators, should have adequate knowledge and skills in this area. However, there is a paucity of research on the knowledge and practice of HOS management. This study used the Knowledge, Attitude and Behavioural Practice Model to assess the management of HOS by colorectal surgery nurses and to explore the factors that influence it. METHOD: Using a multi-centre, cross-sectional study design, 398 colorectal surgery nurses from 6 hospitals in 6 cities in 6 provinces were surveyed using a structured electronic questionnaire to assess general information and knowledge, attitudes and management practices and training needs related to HOS of ileostomy. RESULTS: Colorectal surgery nurses' knowledge and practice of HOS was low. The presence or absence of training is an important factor influencing nurses' knowledge, attitudes and practice, with most nurses having no training and stoma specialist nurses scoring relatively high on knowledge and practice. CONCLUSIONS: Nurses play a very important role in the management of HOS, but this study shows that the current level of knowledge and practice of HOS among colorectal surgery nurses is concerning, and whether or not they have received training is the most critical influencing factor; therefore, training related to HOS is urgently needed.

The effectiveness of health education based on the 5Ts for teach-back on oral nutritional supplements compliance of post-discharge patients after surgery for gastric cancer: a randomized controlled trial.

OBJECTIVE: This study aims to explore the 5Ts teach-back(5Ts) to improve oral nutritional supplements (ONS) compliance of discharged patients after gastric cancer surgery. SETTING AND METHODS: Patients were recruited from the Bethune First Hospital of Jilin University. The patients were randomly assigned to 5Ts (n = 54) and routine health education (n = 54). Weekly ONS compliance was collected by "weekly ONS diary." ONS knowledge, health literacy, and health education satisfaction were collected at baseline and 5 weeks after discharge. Chi-square test, Mann-Whitney U test, and T test were used for data analysis. RESULTS: At the end of the intervention, there were 41 and 40 patients in intervention and control group. 5Ts significantly improve ONS compliance, ONS knowledge level (P = 0.000), health literacy level (P = 0.011), and health education satisfaction (P = 0.009) of patients. At the end of follow-up, there were 30 and 27 patients in two groups, and no significant difference in ONS compliance (P = 0.728). CONCLUSION: The 5Ts can significantly improve patients' ONS compliance and the effect of health education. TRIAL REGISTRATION NUMBER: This prospective trial was registered in the Chinese Clinical Trial Registry at ChiCTR2000040986 ( http://www.chictr.org.cn ). PATIENT OR PUBLIC CONTRIBUTION: Jia Wang and Haiyan Hu contributed to the performance of the study, analysis and interpretation the data, and drafted the manuscript; Jianan Sun and Qing Zhang contributed to the supervision of the study and interpreted the data; Zhiming Chen contributed to the analysis and interpretation the data; Qiuchen Wang contributed to the performance of the study and revised the manuscript; Mingyue Zhu contributed to interpretation the data; Jiannan Yao contributed to revise the manuscript; Hua Yuan and Xiuying Zhang contributed to the conception of the study, performed the study, interpreted the data, and significantly revised the manuscript. All authors screened the final version of the manuscript.

Structure-based mining of a chitosanase with distinctive degradation mode and product specificity.

Chitosan derivates with varying degrees of polymerization (DP) have attracted great concern due to their excellent biological activities. Increasing the abundance of chitosanases with different degradation modes contributes to revealing their catalytic mechanisms and facilitating the production of chitosan derivates. However, the identification of endo-chitosanases capable of producing chitobiose and D-glucosamine (GlcN) from chitosan substrates has remained elusive. Herein, an endo-chitosanase (CsnCA) belonging to the GH46 family was identified based on structural analysis in phylogenetic evolution. Moreover, we demonstrate that CsnCA acts in a random endo-acting manner, producing chitosan derivatives with DP ≤ 2. The in-depth analysis of CsnCA revealed that (GlcN)3 serves as the minimal substrate, undergoing cleavage in the mode that occupies the subsites - 2 to + 1, resulting in the release of GlcN. This study succeeded in discovering a chitosanase with distinctive degradation modes, which could facilitate the mechanistic understanding of chitosanases, further empowering the production of chitosan derivates with specific DP. KEY POINTS: • Structural docking and evolutionary analysis guide to mining the chitosanase. • The endo-chitosanase exhibits a unique GlcN-producing cleavage pattern. • The cleavage direction of chitosanase to produce GlcN was identified.

Clinical characteristics and survival outcomes in patients with primary ovarian carcinoid: A historical cohort study.

INTRODUCTION: Primary ovarian carcinoids are extremely rare ovarian tumors, and there is limited data available on their clinical characteristics and survival outcomes. MATERIAL AND METHODS: We conducted a historical cohort study of 56 patients to investigate their clinical characteristics. The overall survival, disease-specific survival, recurrence-free survival, and potential prognostic factors of these patients were also evaluated. RESULTS: The median age of these patients was 42.0 years (range: 20-71). The average mass and carcinoid size was 7.3 and 0.4 cm, respectively. Elevated tumor marker levels and ascites were observed in 15 and 10 patients, respectively. In 98.2% of the patients, tumors were confined to the ovary, while only one had metastatic disease. Surgery was the mainstay therapy: 37.5% of the patients underwent unilateral salpingo-oophorectomy, 25.0% underwent hysterectomy with bilateral salpingo-oophorectomy, 21.4% underwent ovarian cystectomy, 10.7% underwent comprehensive staging surgery, and 5.4% underwent bilateral salpingo-oophorectomy. Appendectomy and lymphadenectomy were performed in eight and five patients, respectively, but none showed tumor involvement. Chemotherapy was the only adjuvant treatment utilized, and was administered in four patients. Pathological analysis showed that strumal carcinoid was the most predominant subtype, occurring in 66.1% of the patients. The Ki-67 index was reported in 39 patients, 30 of which had an index of no more than 3%, with a maximum of only 5%. Only one relapse occurred after the initial treatment, and that patient experienced recurrences on two occasions, maintaining stable disease after surgery and octreotide therapy. After a median follow-up of 3.6 years, 96.4% of the patients achieved no evidence of disease, while 3.6% were alive with the disease. The 5-year recurrence-free survival rate was 97.9% and no death occurred. No risk factors for recurrence-free survival, overall survival, or disease-specific survival were identified. CONCLUSIONS: The Ki-67 indices were extremely low and prognoses were excellent in patients with primary ovarian carcinoids. Conservative surgery, especially unilateral salpingo-oophorectomy, is preferred. Individualized adjuvant therapy may be considered for patients with metastatic diseases.

Genome Sequencing-Based Mining and Characterization of a Novel Alginate Lyase from Vibrio alginolyticus S10 for Specific Production of Disaccharides.

Alginate oligosaccharides prepared by alginate lyases attracted great attention because of their desirable biological activities. However, the hydrolysis products are always a mixture of oligosaccharides with different degrees of polymerization, which increases the production cost because of the following purification procedures. In this study, an alginate lyase, Alg4755, with high product specificity was identified, heterologously expressed, and characterized from Vibrio alginolyticus S10, which was isolated from the intestine of sea cucumber. Alg4755 belonged to the PL7 family with two catalytic domains, which was composed of 583 amino acids. Enzymatic characterization results show that the optimal reaction temperature and pH of Alg4755 were 35 °C and 8.0, respectively. Furthermore, Alg4755 was identified to have high thermal and pH stability. Moreover, the final hydrolysis products of sodium alginate catalyzed by Alg4755 were mainly alginate disaccharides with a small amount of alginate trisaccharides. The results demonstrate that alginate lyase Alg4755 could have a broad application prospect because of its high product specificity and desirable catalytic properties.

Recent Advances in N-Heterocyclic Small Molecules for Synthesis and Application in Direct Fluorescence Cell Imaging.

Nitrogen-containing heterocycles are ubiquitous in natural products and drugs. Various organic small molecules with nitrogen-containing heterocycles, such as nitrogen-containing boron compounds, cyanine, pyridine derivatives, indole derivatives, quinoline derivatives, maleimide derivatives, etc., have unique biological features, which could be applied in various biological fields, including biological imaging. Fluorescence cell imaging is a significant and effective imaging modality in biological imaging. This review focuses on the synthesis and applications in direct fluorescence cell imaging of N-heterocyclic organic small molecules in the last five years, to provide useful information and enlightenment for researchers in this field.

Recent Advances in Regioselective C-H Bond Functionalization of Free Phenols.

Phenols are important readily available synthetic building blocks and starting materials for organic synthetic transformations, which are widely found in agrochemicals, pharmaceuticals, and functional materials. The C-H functionalization of free phenols has proven to be an extremely useful tool in organic synthesis, which provides efficient increases in phenol molecular complexity. Therefore, approaches to functionalizing existing C-H bonds of free phenols have continuously attracted the attention of organic chemists. In this review, we summarize the current knowledge and recent advances in ortho-, meta-, and para-selective C-H functionalization of free phenols in the last five years.

Engineering Robust Aptamers with High Affinity by Key Fragment Evolution and Terminal Fixation.

Researchers have been looking for ways to fix the structural stability of aptamers so as to achieve the high affinity of aptamers and thus the high sensitivity of analytical methods. Herein, we report a post-selection strategy to facilitate the formation of aptameric structures and enhance their affinity. Key fragments containing crucial bases of parent aptamers were identified and evolved by iterative embedding to form chimeras. The termini of the optimized chimera were then fixed by hybridization to limit their flexibility. Robust aptamers with more stable structures and higher affinity were thus engineered. An anti-okadaic acid aptamer, anti-dinophysistoxin aptamer, and anti-phosphatidylserine (PS) aptamer were engineered in this way, with the affinity enhanced by 160.5-fold, 50.36-fold, and 39.28-fold over that of the parent aptamers, respectively. Furthermore, the practicability of the anti-PS aptamer was validated with a polyA-nanotetrahedron-assisted electrochemical aptasensor. The aptasensor achieved high sensitivity, with the limit of detection as low as 1.741 nM, good accuracy, and good selectivity when monitoring PS in real biosynthesis samples. This study offers a facile and efficient approach to generate robust aptamers and aptasensors for real-world applications.

Antiviral activities of Polygonum perfoliatum L. extract and related phenolic acid constituents against hepatitis B virus.

Chronic hepatitis B virus (HBV) infection is an important public health problem. Polygonum perfoliatum L. is a traditional medicinal herb and has been reported to have pharmacological activities such as anti-inflammatory, antibacterial, and antiviral. In this study, the antiviral activities and mechanisms of Polygonum perfoliatum L. extract against HBV and the effective components were investigated. The results showed that the total extract of Polygonum perfoliatum L. reduced the levels of HBV e antigen (HBeAg) secretion and the viral covalently closed circular DNA (CCC DNA) formation, but had little or no negative effects on viral capsid assembly and pregenomic RNA packaging. Further fractionation showed that the water extract (WE) fraction exerted comparable anti-HBV activities with the total extract, especially in inhibiting the CCC DNA formation and HBeAg production, indicating that the effective antiviral components are mainly distributed in this fraction. Further study showed that the phenolic acids constituents, protocatechuic acid, and gallic acid, but not ethyl caffeate, which is reported enriched in the WE fraction, showed strong anti-HBV activities in inhibiting viral core DNA synthesis, CCC DNA formation, and HBeAg production. These results suggested that the Polygonum perfoliatum L. total extract and the related phenolic acids like protocatechuic acid and gallic acid could inhibit HBV replication and also indicated the potential utility of Polygonum perfoliatum L. and related constituents as sources of novel antivirals against HBV.

Binding Kinetics Toolkit for Analyzing Transient Molecular Conformations and Computing Free Energy Landscapes.

Understanding ligand binding kinetics and thermodynamics, which involves investigating the free, transient, and final complex conformations, is important in fundamental studies and applications for chemical and biomedical systems. Examining the important but transient ligand-protein-bound conformations, in addition to experimentally determined structures, also provides a more accurate estimation for drug efficacy and selectivity. Moreover, obtaining the entire picture of the free energy landscape during ligand binding/unbinding processes is critical in understanding binding mechanisms. Here, we present a Binding Kinetics Toolkit (BKiT) that includes several utilities to analyze trajectories and compute a free energy and kinetics profile. BKiT uses principal component space to generate approximated unbinding or conformational transition coordinates for accurately describing and easily visualizing the molecular motions. We implemented a new partitioning approach to assign indexes along the approximated coordinates that can be used as milestones or microstates. The program can generate input files to run many short classical molecular dynamics simulations and uses milestoning theory to construct the free energy profile and estimate binding residence time. We first validated the method with a host-guest system, aspirin unbinding from ß-cyclodextrin, and then applied the protocol to pyrazolourea compounds and cyclin-dependent kinase 8 and cyclin C complexes, a kinase system of pharmacological interest. Overall, our approaches yielded good agreement with published results and suggest ligand design strategies. The computed unbinding free energy landscape also provides a more complete picture of ligand-receptor binding barriers and stable local minima for deepening our understanding of molecular recognition. BKiT is easy to use and has extensible features for future expansion of utilities for postanalysis and calculations.

Biochemical characterization and cleavage pattern analysis of a novel chitosanase with cellulase activity.

Chitosanases are critical tools for the preparation of active oligosaccharides, whose composition is related to the cleavage pattern of the enzyme. Although numerous chitosanases have been characterized, the glycoside hydrolase (GH) family 5 chitosanases with other activities have rarely been investigated. Herein, a novel and second GH5 chitosanase OUC-Csngly from Streptomyces bacillaris was cloned and further characterized by expression in Escherichia coli BL21 (DE3). Interestingly, OUC-Csngly possessed dual chitosanase and cellulase activities. Molecular docking analysis showed that the C-2 group of sugar units affected the binding of the enzyme to oligosaccharides, which could result in different cleavage patterns toward chito-oligosaccharides (COSs) and cello-oligosaccharides. Further, we characterized OUC-Csngly's distinctive cleavage patterns toward two different types of oligosaccharides. Meanwhile, endo-type chitosanase OUC-Csngly generated (GlcN) - (GlcN)4 from chitosan, was significantly different from other chitosanases. To our knowledge, this is the first report to investigate the different cleavage patterns of chitosanase for COSs and cello-oligosaccharides.Key points• The molecular docking showed C-2 group of sugar units in substrate affecting the cleavage pattern.• The first chitosanase exhibited different cleavage patterns towards chito- and cello-oligosaccharides.• The groups at C-2 influence the subsite composition of the enzyme's active cleft.

Insights into promiscuous chitosanases: the known and the unknown.

Chitosanase, a glycoside hydrolase (GH), catalyzes the cleavage of ß-1,4-glycosidic bonds in polysaccharides and is widely distributed in nature. Many organisms produce chitosanases, and numerous chitosanases in the GH families have been intensely studied. The reported chitosanases mainly cleaved the inter-glucosamine glycosidic bonds, while substrate specificity is not strictly unique due to the existence of bifunctional or multifunctional activity profiles. The promiscuity of chitosanases is essential for the different pathways of biomass polysaccharide conversion and understanding of the chitosanase evolutionary process. However, the reviews for this aspect are completely unknown. This review provides an overview of the promiscuous activities, also considering the substrate and product specificity of chitosanases observed to date. These contribute to important implications for the future discovery and research of promiscuous chitosanases and applications related to biomass conversion. KEY POINTS: • The promiscuity of chitosanases is reviewed for the first time. • The current review provides insights into the substrate specificity of chitosanases. • The mode-product relationship and prospect of promiscuous chitosanases are highlighted.

A multifunctional composite hydrogel as an intrinsic and extrinsic coregulator for enhanced therapeutic efficacy for psoriasis.

BACKGROUND: Psoriasis is a chronic relapsing immunological skin disease characterized by multiple cross-talk inflammatory circuits which are relevantly associated with abnormal cross-reactivity between immune cells and keratinocytes (KCs). It may be inadequate to eradicate complicated pathogenesis only via single-mode therapy. To provide optimal combinatory therapeutics, a nanocomposite-based hydrogel was constructed by loading methotrexate (MTX) into ZnO/Ag to realize combined multiple target therapy of psoriasis. RESULTS: In this composite hydrogel, ZnO hybrid mesoporous microspheres were utilized both as drug carriers and reactive oxygen species (ROS)-scavenging nanoparticles. A proper amount of Ag nanoparticle-anchored ZnO nanoparticles (ZnO/Ag) was functionalized with inherent immunoregulatory property. The experiments showed that ZnO/Ag nanoparticles could exhibit a self-therapeutic effect that was attributed to reducing innate cytokine profiles by inactivating p65 in proinflammatory macrophages and abrogating secretion of adaptive cytokines in KCs by downregulating ROS-mediated STAT3-cyclin D1 signaling. A preferable antipsoriatic efficacy was achieved via topical administration of this hydrogel on the imiquimod (IMQ)-induced psoriasis mice model, demonstrating the superior transdermal delivery and combined enhancement of therapeutic efficacy caused by intrinsic nanoparticles and extrinsic MTX. CONCLUSION: This composite hydrogel could serve as a multifunctional, nonirritating, noninvasive and effective transcutaneous nanoagent against psoriasis.

Anti-breast cancer sinomenine derivatives via mechanisms of apoptosis induction and metastasis reduction.

Sinomenine, a morphinane-type isoquinoline-derived alkaloid, was first isolated from stems and roots of Sinomenium diversifolius (Miq.) in 1920. Later discovery by researchers confirmed various essential biological efficacy sinomenine exerted in vitro and in vivo. In this study, a series of 15 sinomenine/furoxan hybrid compounds were designed and synthesised in search of a TNBC drug candidate. Some of the target compounds exhibited strong antiproliferative activities against cancer cell lines, especially for TNBC cells, compared to positive controls. Among them, hybrid 7Cc exerted superior cytotoxic effects on cancer cell lines with exceptionally low IC50 (0.82 µM) against MDA-MB-231 cells with the highest safety index score. Further studies in mechanism displayed that 7Cc could induce an S phase cell cycle arrest, stimulate apoptosis in MDA-MB-231 cells, disrupt mitochondrial membrane potential and exert a genotoxic effect on DNA in cancer cells. In addition, 7Cc also notably inhibited MDA-MB-231 cells in both migration, invasion and adhesion.

Design and synthesis of chromone-nitrogen mustard derivatives and evaluation of anti-breast cancer activity.

Chromone has emerged as one of the most important synthetic scaffolds for antitumor activity, which promotes the development of candidate drugs with better activity. In this study, a series of nitrogen mustard derivatives of chromone were designed and synthesised, in order to discover promising anti-breast tumour candidates. Almost all target derivatives showed antiproliferative activity against MCF-7 and MDA-MB-231 cell lines. In particular, methyl (S)-3-(4-(bis(2-chloroethyl)amino)phenyl)-2-(5-(((6-methoxy-4-oxo-4H-chromen-3-yl)methyl)amino)-5-oxopentanamido)propanoate showed the most potent antiproliferative activity with IC50 values of 1.83 and 1.90 µM, respectively, and it also exhibited certain selectivity between tumour cells and normal cells. Further mechanism exploration against MDA-MB-231 cells showed that it possibly induced G2/M phase arrest and apoptosis by generating intracellular ROS and activating DNA damage. In addition, it also inhibited MDA-MB-231 cells metastasis, invasion and adhesion. Overall, methyl (S)-3-(4-(bis(2-chloroethyl)amino)phenyl)-2-(5-(((6-methoxy-4-oxo-4H-chromen-3-yl)methyl)amino)-5-oxopentanamido)propanoate showed potent antitumor activities and relatively low side effects, and deserved further investigation.