Recent advances in the chemistry and biology of oleanolic acid and its derivatives

Facile preparation of W/O Pickering emulsion gels stabilized with oleanolic acid for the co-delivery of curcumin and epigallocatechin gallate

In this study, natural oleanolic acid (OA) was used to prepare water-oil Pickering emulsion gels via a one-pot one-step ultrasonic-assisted emulsification method. Characterization revealed that OA self-assembled into nanoparticles in oil via hydrogen bonding, and these nanoparticles played dual roles in interfacial stabilization and network stabilization. The resulting emulsion gels were mainly elastic and had shear-thinning characteristics with a certain thixotropic recovery ability. Additionally, they exhibited excellent stability when exposed to high temperatures (63 and 90 °C), subjected to freeze-thaw treatments, or long-term storage (4 °C, 30 days). When used as carriers, they provide excellent protection for curcumin (Cur) and epigallocatechin gallate (EGCG) against light- and heat-induced degradation. Additionally, they protected them from digestion in the simulated gastric fluids and targeted them for controlled release in the simulated intestinal fluids. This study not only provides a simple preparation method for fabricating OA-structured emulsion gels but also proposes an effective co-delivery system for hydrophobic and hydrophilic compounds.

Progress in the Study of Chemical Constituents of Actaea cimicifuga and Actaea erythrocarpa and Their Biological Potential

For the first time, hydroethanolic extracts from Actaea cimicifuga and Actaea erythrocarpa were analyzed using LC-HRMS, HPLC, and spectrometry in this study. Extracts from the above-ground parts of Actaea species exhibited higher concentrations of saponins (up to 248 mg/g of DE), coumarins (up to 162 mg/g of DE), flavonols (up to 32 mg/g of DE), and catechins (up to 11 mg/g of DE) compared to extracts from the underground parts. The concentrations of phenolic acids (up to 112 mg/g of DE) and tannins (up to 202 mg/g of DE) in the underground parts were comparable to or even higher than those in the above-ground parts of the two analyzed species. The concentration of the main metabolites detected was higher in the extract of A. erythrocarpa than that of A. cimicifuga. The metabolite profile of the extracts from both species showed 66 compounds, including chromones, coumarins, phenolic and nitrogenous compounds, fatty acids, and triterpenes. The HPLC analysis of the four extracts revealed that the concentration of caffeic acid (0.74 mg/g of the dry extract [DE]) was the highest in the extract from the underground part of A. erythrocarpa, whereas the extract from the above-ground part of this species showed the highest levels of ferulic (1.16 mg/g of DE) and isoferulic acids (1.49 mg/g of DE) and of hyperoside (13.05 mg/g of DE). The study of biological activity showed that A. erythrocarpa is most promising for further research, with the highest antioxidant activity found in the underground parts of this species (IC50 = 79.7 μg/mL) compared to the above-ground parts (IC50 = 85.8 μg/mL). In addition, the extract from the above-ground part of A. erythrocarpa was found to exhibit the greatest cytotoxic activity among the studied specimens against 3T3-L1, HepG2, and MDA-MB-231 cells.

Design and synthesis of azole derivatives of echinocystic acid as α-glucosidase inhibitors with hypoglycemic activity

Diabetes mellitus necessitates strict control of postprandial hyperglycemia via α-glucosidase inhibitors. In this study, novel azole derivatives of Echinocystic acid (EA), a natural pentacyclic triterpenoid, were synthesized through molecular hybridization to enhance hypoglycemic potential. Compound A4 exhibited superior α-glucosidase inhibition (IC50 = 2.72 μM) than that of EA (IC50 = 59.91 μM), and acarbose (IC50 = 342.0 μM). Kinetic analysis revealed mixed-type inhibition (Ki = 15.31 μM, Kis = 10.23 μM), suggesting ternary complex formation. Analysis by spectroscopic studies confirmed A4 altered the enzyme's microenvironment and secondary structure. The combination of molecular docking and molecular dynamics simulations further elucidated the interaction between A4 and α-glucosidase. A4 enhanced binding stability through π-cation and π-π stacking interactions, with low RMSD values indicating structural stability. In vivo studies showed that A4 has an excellent safety profile, with no organ damage observed at a single dose of 0.5 g/kg. In a sucrose loading test in normal mice, A4 demonstrated glucose control comparable to that of acarbose at the same dose. Diabetic mice treated with A4 exhibited reduced fasting blood glucose, improved glucose tolerance, lipid normalization, and antioxidant effects, underscoring its therapeutic promise.

Monotherapy or Combination Therapy of Oleanolic Acid? From Therapeutic Significance and Drug Delivery to Clinical Studies: A Comprehensive Review

Oleanolic acid is a pentacyclic triterpenoid molecule widely distributed throughout medicinal plants. This naturally occurring oleanolic acid has attracted considerable interest due to its wide range of pharmacological characteristics, notably its cytotoxic effects on various human cancer cell lines, making it a potential candidate for extensive therapeutic uses. In vivo studies have shown that oleanolic acid possesses hepatoprotective, cardioprotective, anti-inflammatory, and antimicrobial properties. The inherent obstacles of oleanolic acid, such as low permeability, limited bioavailability, and poor water solubility, have restricted its therapeutic applicability. However, recent developments in drug delivery techniques have given oleanolic acid an additional advantage by overcoming issues with its solubility, stability, and bioavailability. This review briefly summarises the signalling pathways involved in the pharmacological activities of oleanolic acid as a monotherapy and in combination with other drugs. The review devotes a substantial portion to explaining the formulation developments, emphasising nanotechnology as a key factor in the improvement of the therapeutic potential of oleanolic acid. Several investigated novel formulations have been discussed, including liposomes, nanoemulsions, phospholipids, and polymeric nanoparticles, emerging synergistically as an efficient delivery of oleanolic acid and several other drugs. Based on our literature evaluation, it can be inferred that combination therapy had a more favourable outcome than using oleanolic acid alone in in vivo trials, primarily due to its synergistic effects. However, it is essential to note that this finding was inconsistent across all investigations. The combination of oleanolic acid with other drugs has not yet been considered for clinical trials. However, it is interesting that neither therapy has obtained approval from the U. S. Food and Drug Administration.

Design and semisynthesis of novel oleanolic acid-based tertiary amide derivatives as promising antifungal agents against phytopathogenic fungi

To further explore and discover natural products-based antifungal agents, seventeen tertiary amide-oleanolic acid hybrids were designed and synthesized, and structurally confirmed by 1H NMR, 13C NMR, HRMS, and melting point. Bioassay results illustrated that derivative 4 k exhibited prominent in vitro inhibitory activity against the mycelium growth of Gaeumannomyces graminis and Valsa mali with the EC50 values of 41.77 and 43.96 μg/mL, respectively. Meanwhile, the structure-activity relationships were also summarized. Moreover, in vivo control efficacy demonstrated that derivative 4 k displayed remarkable curative effect (CE) against V. mali at 200 μg/mL with the value of 52.6%, evidently superior to that of the positive control carbendazim (41.5%). Besides, derivative 4 k also exhibited good CE against Botrytis cinerea at 200 μg/mL with the value of 33.0%. Scanning electron microscope analysis initially indicated that derivative 4 k may exert its antifungal effect by leading to abnormal morphology on the mycelium surface, resulting in the aberrant hypha growth.

Synthesis, Anti-Oomycete and Anti-Fungal Activities of Anhydride Derivatives of Oleanolic Acid

Oleanolic acid is a pentacyclic triterpenoid extracted and isolated from the fruit of plants in the Ligustrum lucidum Ait. in the family Oleaceae. To discover biorational natural product-based pesticides, a series of oleanolic acid derivatives containing anhydride active skeletons were prepared by ingeniously introducing an active acyloxy group at its C-28 carboxyl position, and their structures were well characterized by 1H-NMR, 13C NMR, HRMS, and m.p. The stereochemical configuration of compound 8 e was confirmed using single-crystal X-ray diffraction. Furthermore, bioactivities of these compounds as anti-oomycete and anti-fungal agents against two serious agricultural pests, Phytophthora capsici (P. capsici) and Fusarium graminearum (F. graminearum) we assessed. Amongst evaluated compounds, 1) Compounds 8 h and 8 j displayed significant anti-oomycete against P. capsici, with EC50 values of 54.73 and 65.15 mg/L, respectively. 2) The target compounds have obvious selectivity, and their anti-oomycete activity is significantly better than their anti-fungal activity. 3) Interestingly, there are significant differences in the structure-activity relationship of different substituents or the same substituent at different positions anti-oomycete and anti-fungal against P. capsici and F. graminearum, respectively. The study provides an idea for further exploring the bioactivities of 28-acyloxyoleanolic acid derivatives, and develops the application of 28-acyloxyoleanolic acid derivatives containing anhydride in agriculture.