Features of the Bioconversion of Pentacyclic Triterpenoid Oleanolic Acid Using Rhodococcus Actinobacteria

The ability of actinobacteria of the genus Rhodococcus to transform oleanolic acid (OA), a plant pentacyclic triterpenoid, was shown for the first time using bioresources of the Regional Specialized Collection of AlkanotrophicMicroorganisms (IEGM; WDCM #768;www.iegmcol.ru). The most promising strains (R.opacus IEGM 488 and R.rhodochrousIEGM 285) were selected, and these catalyzed80% bioconversion of OA (0.5 g/L) in the presence of n-hexadecane (0.1% v/v) for seven days. The process of OA bioconversion was accompanied by a gradual decrease in the culture medium pH. Adaptive responses of bacterial cells to the OA effects included the formation of compact cellular aggregates, a marked change in the surface-to-volume ratio of cells, and a significant increase in the Zeta potential values. The results demonstrated that the process of OA bioconversion was catalyzed by membrane-bound enzyme complexes. Participation of cytochrome P450-dependent monooxygenases in the oxidation of the OA moleculewas confirmedusing specific inhibitors. The obtained data expand our knowledge on the catalytic activity of actinobacteria of the genus Rhodococcus and their possible use as biocatalysts for the bioconversion of complex hydrophobic compounds. The results can also be used inthe searchfor promising OA derivatives to be used in the synthesis of biologically active agents. Keywords: bioconversion, oleanolic acid, Rhodococcus, biologically active compounds

A direct high-throughput protein quantification strategy facilitates discovery and characterization of a celastrol-derived BRD4 degrader

We describe a generalizable time-resolved Förster resonance energy transfer (TR-FRET)-based platform to profile the cellular action of heterobifunctional degraders (or proteolysis-targeting chimeras; PROTACs), capable of both accurately quantifying protein levels in whole cell lysates in less than 1 h and measuring small-molecule target engagement to endogenous proteins, here specifically for human bromodomain-containing protein 4 (BRD4). The detection mix consists of a single primary antibody targeting the protein of interest, a luminescent donor-labeled anti-species nanobody, and a fluorescent acceptor ligand. Importantly, our strategy can readily be applied to other targets of interest and will greatly facilitate the cell-based profiling of small molecule inhibitors and PROTACs in high-throughput format with unmodified cell lines. We furthermore validate our platform in the characterization of celastrol, a p-quinone methide-containing pentacyclic triterpenoid, as a broad cysteine-targeting E3 ubiquitin ligase warhead for potent and efficient targeted protein degradation

Comparative Metabolomics of Reproductive Organs in the Genus Aesculus (Sapindaceae) Reveals That Immature Fruits Are a Key Organ of Procyanidin Accumulation and Bioactivity

Fruit from A. hippocastanum L. are used commercially for chronic venous insufficiency (CVI). The isomeric mixture of pentacyclic triterpenoid saponins (β-aescin) exert anti-inflammatory effects. Hence, research has focused on β-aescin, yet the diversity, accumulation, and bioactivity of organ-specific secondary metabolites represent missed pharmacological opportunities. To this end, we applied an untargeted metabolomics approach by liquid chromatography—tandem mass spectrometry (LC–MS/MS) to the chemical profiles of flowers, immature fruits, and pedicels from 40 specimens across 18 species of Aesculus. Principal component analysis (PCA), orthogonal partial least squares (OPLS-DA), and molecular networking revealed stronger chemical differences between plant organs, than between species. Flowers are rich in glycosylated flavonoids, pedicels in organic acids and flavonoid aglycones, and immature fruits in monomeric flavan-3-ols and procyanidins. Although a high diversity of flavonoids and procyanidins was observed, the relative amounts differed by plant organ. Fruit extracts demonstrated the strongest antifungal (Saccharomyces cerevisiae) and antioxidant activity, likely from the procyanidins. Overall, secondary metabolite profiles are organ-specific, and fruits accumulate antifungal and antioxidant compounds. Due to the chemical similarity between species, similar effects may be achieved between species. This creates incentives for further exploration of the entire genus, in bioprospecting for potential therapeutic leads.

Epigenetic modification associated with climate regulates betulin biosynthesis in birch

The Betula genus contains pentacyclic triterpenoid betulin known for its environmental adaptation and medicinal properties. However, the mechanisms underlying betulin biosynthesis responding to climate change remain unclear. In this study, the role of epigenetic modification (DNA methylation) in betulin biosynthesis was examined and how climatic factors influence it. Whole-genome bisulfite sequencing was performed for greenhouse-grown Chinese white birch (Betula platyphylla Sukaczev) treated with DNA methylation inhibitor zebularine (ZEB) and a natural birch population in Northeast China. ZEB treatment significantly affected the CHH methylation level of transposable elements and betulin content in a hormesis dose-dependent manner. The methylation and expression of bHLH9, a key transcriptional factor controlling betulin biosynthesis, were also consistently affected by ZEB treatment as a hormetic dose–response. In the natural population, there was a positive correlation between promoter methylation of bHLH9 and summer precipitation, while winter temperature was negatively correlated. Thus climate-dependent methylation of bHLH9 regulates the expression of downstream genes involved in betulin biosynthesis. This study highlights the role of environmental signals to induce epigenetic changes that result in betulin production, possibly helping to develop resilient plants to combat ongoing climate change and enhance secondary metabolite production.

Efficacy of Ursolic Acid-Enriched Water-Soluble and Not Cytotoxic Nanoparticles against Enterococci

Ursolic acid (UA), a pentacyclic triterpenoid acid found in many medicinal plants and aromas, is known for its antibacterial effects against multi-drug-resistant (MDR) Gram-positive bacteria, which seriously threaten human health. Unfortunately, UA water-insolubility, low bioavailability, and systemic toxicity limit the possibilities of its application in vivo. Consequently, the beneficial activities of UA observed in vitro lose their potential clinical relevance unless water-soluble, not cytotoxic UA formulations are developed. With a nano-technologic approach, we have recently prepared water-soluble UA-loaded dendrimer nanoparticles (UA-G4K NPs) non-cytotoxic on HeLa cells, with promising physicochemical properties for their clinical applications. In this work, with the aim of developing a new antibacterial agent based on UA, UA-G4K has been tested on different strains of the Enterococcus genus, including marine isolates, toward which UA-G4K has shown minimum inhibitory concentrations (MICs) very low (0.5–4.3 µM), regardless of their resistance to antibiotics. Time-kill experiments, in addition to confirming the previously reported bactericidal activity of UA against E. faecium, also established it for UA-G4K. Furthermore, cytotoxicity experiments on human keratinocytes revealed that nanomanipulation of UA significantly reduced the cytotoxicity of UA, providing UA-G4K NPs with very high LD50 (96.4 µM) and selectivity indices, which were in the range 22.4–192.8, depending on the enterococcal strain tested. Due to its physicochemical and biological properties, UA-G4K could be seriously evaluated as a novel oral-administrable therapeutic option for tackling difficult-to-treat enterococcal infections.

Therapeutic Potential of Ursolic Acid in Cancer and Diabetic Neuropathy Diseases

Ursolic acid (UA) is a pentacyclic triterpenoid frequently found in medicinal herbs and plants, having numerous pharmacological effects. UA and its analogs treat multiple diseases, including cancer, diabetic neuropathy, and inflammatory diseases. UA inhibits cancer proliferation, metastasis, angiogenesis, and induced cell death, scavenging free radicals and triggering numerous anti- and pro-apoptotic proteins. The biochemistry of UA has been examined broadly based on the literature, with alterations frequently having been prepared on positions C-3 (hydroxyl), C12–C13 (double bonds), and C-28 (carboxylic acid), leading to several UA derivatives with increased potency, bioavailability and water solubility. UA could be used as a protective agent to counter neural dysfunction via anti-oxidant and anti-inflammatory effects. It is a potential therapeutic drug implicated in the treatment of cancer and diabetic complications diseases provide novel machinery to the anti-inflammatory properties of UA. The pharmacological efficiency of UA is exhibited by the therapeutic theory of one-drug → several targets → one/multiple diseases. Hence, UA shows promising therapeutic potential for cancer and diabetic neuropathy diseases. This review aims to discuss mechanistic insights into promising beneficial effects of UA. We further explained the pharmacological aspects, clinical trials, and potential limitations of UA for the management of cancer and diabetic neuropathy diseases.

Beneficial Effects of Ursolic Acid and Its Derivatives—Focus on Potential Biochemical Mechanisms in Cardiovascular Conditions

Ursolic acid (UA) is a natural pentacyclic triterpenoid found in a number of plants such as apples, thyme, oregano, hawthorn and others. Several in vitro and in vivo studies have presented its anti-inflammatory and anti-apoptotic properties. The inhibition of NF-κB-mediated inflammatory pathways and the increased scavenging of reactive oxygen species (ROS) in numerous ways seem to be the most beneficial effects of UA. In mice and rats, administration of UA appears to slow down the development of cardiovascular diseases (CVDs), especially atherosclerosis and cardiac fibrosis. Upregulation of endothelial-type nitric oxide synthase (eNOS) and cystathionine-λ-lyase (CSE) by UA may suggest its vasorelaxant property. Inhibition of metalloproteinases activity by UA may contribute to better outcomes in aneurysms management. UA influence on lipid and glucose metabolism remains inconsistent, and additional studies are essential to verify its efficacy. Furthermore, UA derivatives appear to have a beneficial impact on the cardiovascular system. This review aims to summarize recent findings on beneficial effects of UA that may make it a promising candidate for clinical trials for the management of CVDs.

Role of Pentacyclic Triterpenoid Acids in the Treatment of Bladder Cancer

: Bladder cancer carries a poor prognosis and has proven resistance to chemotherapy. Pentacyclic Triterpenoid Acids (PTAs) are natural bioactive compounds that have a well-known impact on cancer research because of their cytotoxic and chemopreventive activities. This review focuses on bladder cancer which can no longer be successfully treated by DNA damaging drugs. Unlike most of the existing drugs against bladder cancer, PTAs are non-toxic to normal cells. Collecting findings from both in vitro and in vivo studies, it has been concluded that PTAs may serve as promising agents in future bladder cancer therapy. In this review, the roles of various PTAs in bladder cancer have been explored, and their mechanisms of action in the treatment of bladder cancer have been described. Specific PTAs have been shortlisted from each of the chief skeletons of pentacyclic triterpenoids, which could be effective against bladder cancer because of their mode of action. This review thereby throws light on the multi targets and mechanisms of PTAs, which are responsible for their selective anticancer effects and provides guidelines for further research and development of new natural antitumor compounds.

Delivery of Ursolic Acid by Polyhydroxybutyrate Nanoparticles for Cancer Therapy: in silico and in vitro Studies

Ursolic acid (UA), a pentacyclic triterpenoid and a phytochemical, is a potent inhibitory agent against proliferation of various tumors. Polyhydroxybutyrate nanoparticles (PHB NPs) are preferred in therapeutics due to their drug-stabilizing property and enhanced biological activity. In this study, PHB NPs were utilized to deliver and enhance the bioavailability of UA against cancer cells (HeLa). Further, molecular docking and dynamic studies were conducted to calculate the binding affinity and stability of UA at the active site of target protein (epidermal growth factor receptor-EGFR). The PHB NPs revealed the average size as 150–200 nm in TEM, which were used in subsequent experiments. The cytoplasmic uptake of nanoparticles was confirmed by florescent microscopy. The encapsulation potential of PHB NPs with UA was assessed by UV–visible spectrophotometer as 54%. Besides, the drug release behavior, cytotoxicity and the regulation of apoptosis were investigated in vitro. The cytotoxicity results revealed that the maximum efficiency of drug delivery was at 96th hour.