Synthesis and Anticancer Activity of Indole-Functionalized Derivatives of Betulin

Indoles as promising Therapeutics: A review of recent drug discovery efforts

Indole, a fundamental heterocyclic core, has emerged as a cornerstone in the medicinal chemistry due to its diverse biological activities and structural versatility. This aromatic compound, present in natural as well as synthetic compounds, offers a versatile platform for the drug discovery. By strategically incorporating functional groups or pharmacophores, researchers can tailor indole-derivatives to target a wide range of diseases. This review delves into the multifaceted applications of indole derivatives, highlighting their potential as therapeutic agents for cancer, diabetes, depression, Alzheimer's diseases, Parkinson's disease, etc. emphasizing how indole derivatives can enhance potency and selectivity. By understanding the structure-activity relationship of indole compounds, scientists can develop innovative drug candidates with improved therapeutic profiles. The review highlights the diverse nature of indole-based derivatives along with the structure-activity relationshipThe current review comprehensively covers the advancements and developments in the field over the past seven years, specifically from 2017 to 2024. This timeframe was selected to provide an up-to-date and thorough analysis of recent progress, capturing significant trends, breakthroughs, and emerging insights within the domain. By focusing on this period, the review ensures relevance and highlights the evolving landscape of research, offering a detailed synthesis of key findings and their implications for future studies.

Simultaneous Qualitative and Quantitative Analyses of 41 Constituents in Uvaria macrophylla Leaves Screen Antioxidant Quality-Markers Using Database-Affinity Ultra-High-Performance Liquid Chromatography with Quadrupole Orbitrap Tandem Mass Spectrometry

To date, no study has focused on Uvaria macrophylla leaves with various traditional efficiencies. This paper therefore applied a database affinity ultra-high-performance liquid chromatography with quadrupole Orbitrap tandem mass spectrometry (UHPLC-Q-Orbitrap-MS/MS) strategy to analyze the lyophilized aqueous extract of U. macrophylla leaves. Through database comparison and MS fragment elucidation, this study has putatively identified 41 constituents belonging to flavonoid, phenolic acid, steroid, and saccharide natural product classifications. Significantly, four groups of isomers (liquiritigenin vs. isoliquiritigenin vs. pinocembrin; oroxylin A vs. wogonin vs. galangin 3-methyl ether; isoquercitrin vs. hyperoside; protocatechuic acid vs. 2,5-dihydroxybenzoic acid) have been successfully distinguished from each other. All of 41 constituents were then subjected to a quantitative analysis based on linear regression equation established by the above UHPLC-Q-Orbitrap-MS/MS strategy and an ABTS+•-scavenging antioxidant assay. Finally, the chemical content was multiplied by the corresponding ABTS+•-scavenging percentage to calculate the antioxidant contribution. It was shown that the chemical contents of 41 constituents varied from 0.003 ± 0.000 to 14.418 ± 1.041 mg/g, and gallic acid showed the highest antioxidant contribution. Gallic acid is considered as a suitable antioxidant quality-marker (Q-marker) of U. macrophylla leaves. These findings have scientific implications for the resource development and quality control of U. macrophylla leaves.

Assessment of the Lipophilicity of Indole Derivatives of Betulin and Their Toxicity in a Zebrafish Model

There are scientific studies indicating that the attachment of an indole moiety to the triterpene scaffold can lead to increased anticancer potential. Lipophilicity is one of the factors that may influence biological properties and is therefore an important parameter to determine for newly obtained compounds as drug candidates. In the present study, previously synthesized 3 and/or 28-indole-betulin derivatives were evaluated for lipophilicity by reversed-phase thin-layer chromatography. The experimental values of lipophilicity (logPTLC) were then subjected to correlation analysis with theoretical values of logP, as well as for selected physicochemical and pharmacokinetic parameters and anticancer activity. A toxicity test using zebrafish embryos and larvae was also conducted. High correlation was observed between the experimental and theoretical values of lipophilicity. We presented correlation equations and statistical parameters describing the relationships between logPTLC and several physicochemical and ADME parameters. We also revealed the lack of correlation between the experimental values of lipophilicity and anticancer activity. Moreover, experiments on zebrafish have confirmed no toxicity of the tested compounds, which was consistent with the results of the in silico toxicity analysis. The results demonstrated, using the example of indole derivatives of betulin, the utility of lipophilicity values in the context of predicting the biological activity of new compounds.

Efficient synthesis of indole-chalcones based glycohybrids and their anticancer activity

Indole based glycosides belong to the class of pharmacologically active molecules and found in diverse natural compounds. Herein, we report the synthesis of 1,2,3-triazole bridged chirally enriched diverse indole-chalcones based glycohybrids. Three series of glycohybrids were designed and efficiently synthesized using d-glucose, d-galactose and d-mannose derived 1-azido glycosides. The reactions sequence involved were, the synthesis of indole derived chalcones which were formed via Claisen-Schmidt condensation reaction and subsequently N-propargylation which leads to the production of N-propargylated indole-chalcones. The N-propargylated indole-chalcones get transformed into 1,2,3-triazole bridged indole-chalcone based glycohybrids by reacting with 1-azido sugar glycosides under click-chemistry reaction conditions. Further, the biological activity of synthesized glycohybrids (n = 27) was assessed in-vitro against MDA-MB231, MCF-7, MDA-MB453 cancer, and MCF-10A normal cell lines. The selected compounds showed potent anti-oncogenic properties against MCF-7 and MDA-MB231 breast cancer cell line with IC50 values of 1.05 µM and 11.40 µM respectively, with very good selectivity index (SI > 161). The active compounds show better binding affinity as compared to co-crystallized inhibitor 1-(tert-butyl)-3-(p-tolyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine (PP1) with HCK (PTKs) proteins in molecular docking studies.

Synthesis, Pharmacokinetic Profile, Anticancer Activity and Toxicity of the New Amides of Betulonic Acid-In Silico and In Vitro Study

Betulonic acid (B(O)A) is a pentacyclic lupane-type triterpenoid that widely exists in plants. There are scientific reports indicating anticancer activity of B(O)A, as well as the amides and esters of this triterpenoid. In the first step of the study, the synthesis of novel amide derivatives of B(O)A containing an acetylenic moiety was developed. Subsequently, the medium-soluble compounds (EB171 and EB173) and the parent compound, i.e., B(O)A, were investigated for potential cytotoxic activity against breast cancer (MCF-7 and MDA-MB-231) and melanoma (C32, COLO 829 and A375) cell lines, as well as normal human fibroblasts. Screening analysis using the WST-1 test was applied. Moreover, the lipophilicity and ADME parameters of the obtained derivatives were determined using experimental and in silico methods. The toxicity assay using zebrafish embryos and larvae was also performed. The study showed that the compound EB171 exhibited a significant cytotoxic effect on cancer cell lines: MCF-7, A-375 and COLO 829, while it did not affect the survival of normal cells. Moreover, studies on embryos and larvae showed no toxicity of EB171 in an animal model. Compared to EB171, the compound EB173 had a weaker effect on all tested cancer cell lines and produced less desirable effects against normal cells. The results of the WST-1 assay obtained for B(O)A revealed its strong cytotoxic activity on the examined cancer cell lines, but also on normal cells. In conclusion, this article describes new derivatives of betulonic acid-from synthesis to biological properties. The results allowed to indicate a promising direction for the functionalization of B(O)A to obtain derivatives with selective anticancer activity and low toxicity.

Steglich esterification: A versatile synthetic approach toward the synthesis of natural products, their analogues/derivatives

The exploitation of natural products and their analogues in the field of pharmacology has been regarded as of great importance. It can be attributed to the fact that these scaffolds exhibit diverse chemical properties, distinct biological activities and zenith specificity in their biochemical processes, enabling them to act as favorable structures for lead compounds. The synthesis of natural products has been a crafty and hard-to-achieve task. Steglich esterification reaction has played a significant role in that area. It is a mild and efficient technique for constructing ester linkages. This technique involves the establishment of ester moiety via a carbodiimide-based condensation of a carboxylic acid with an alcohol, thiol or an amine catalyzed by dimethyl aminopyridine (DMAP). Specifically, labile reagents with multiple reactive sites are esterified efficiently with the classical and modified Steglich esterification conditions, which accounts for their synthetic utility. This review encloses the performance of the Steglich esterification reaction in forging the ester linkage for executing the total synthesis of natural products and their derivatives since 2018.

Synthesis, Pharmacological Properties, and Potential Molecular Mechanisms of Antitumor Activity of Betulin and Its Derivatives in Gastrointestinal Cancers

Gastrointestinal (GI) cancers are an increasingly common type of malignancy, caused by the unhealthy lifestyles of people worldwide. Limited methods of treatment have prompted the search for new compounds with antitumor activity, in which betulin (BE) is leading the way. BE as a compound is classified as a pentacyclic triterpene of the lupane type, having three highly reactive moieties in its structure. Its mechanism of action is based on the inhibition of key components of signaling pathways associated with proliferation, migration, interleukins, and others. BE also has a number of biological properties, i.e., anti-inflammatory, hepatoprotective, neuroprotective, as well as antitumor. Due to its poor bioavailability, betulin is subjected to chemical modifications, obtaining derivatives with proven enhanced pharmacological and pharmacokinetic properties as a result. The method of synthesis and substituents significantly influence the effect on cells and GI cancers. Moreover, the cytotoxic effect is highly dependent on the derivative as well as the individual cell line. The aim of this study is to review the methods of synthesis of BE and its derivatives, as well as its pharmacological properties and molecular mechanisms of action in colorectal cancer, hepatocellular carcinoma, gastric cancer, and esophageal cancer neoplasms.

The anti-breast cancer potential of indole/isatin hybrids

Breast cancer (BC) is one of the most prevalent malignancies and the major contributor to cancer mortality in women globally, with a high degree of heterogeneity and a dismal prognosis. As drug resistance is responsible for most BC fatalities and advanced BC is currently considered incurable, finding innovative anti-BC chemotherapeutics is urgently required. Indole and its analog isatin (indole-1H-2,3-dione) are prominent pharmacophores in the development of novel medications, and their derivatives exhibit strong anticancer activities, also against BC. In particular, indole/isatin hybrids exhibit significant potency against BC including multidrug-resistant forms and excellent selectivity by influencing a variety of biological targets associated with the disease, supplying helpful building blocks for the identification of potential new BC treatment options. This review includes articles from 2020 to the present and provides insights into the in vitro and in vivo anti-BC potential, molecular mechanisms, and structure-activity relationships (SARs) of indole/isatin hybrids that may be helpful in the development of innovative anti-BC chemotherapeutics.