The aim of the study was to determine the antioxidant activity and assess the lipophilicity and skin penetration of eugenyl chloroacetate (EChA), eugenyl dichloroacetate (EDChA), and eugenyl trichloroacetate (ETChA). Identification of the obtained products was based on gas chromatography (GC), infrared spectroscopy (FTIR/ATR), gas chromatography coupled with mass spectrometry (GC-MS), and the analysis of ¹³C-NMR and ¹H-NMR spectra. The antioxidative capacity of the derivatives obtained was determined by the DPPH free radical reduction method, while the octanol/water partition coefficient (shake-flask method) was tested to determine the lipophilicity of these compounds. In the next stage of testing EDChA and ETChA–(compounds characterized by the highest degree of free radical scavenging), the penetration of DPPH through pig skin and its accumulation in the skin were evaluated. For comparison, penetration studies of eugenol alone as well as dichloroacetic acid (DChAA) and trichloroacetic acid (TChAA) were also carried out. The antioxidant activity (DPPH, ABTS, and Folin–Ciocalteu methods) of the fluid that penetrated through pig skin was also evaluated. The in vitro pig skin penetration study showed that eugenol derivatives are particularly relevant for topical application. The obtained derivatives were characterized by a high level of antioxidant activity estimated after 24 h of conducting the experiment, which indicates long-term protection against reactive oxygen species (ROS) in the deeper layers of the skin.

This review discusses the antioxidant potential of oleanolic acid, a triterpene compound present in many medicinal and edible plants. The authors analyze various studies that confirm numerous pharmacological properties of this compound, such as its anticancer, antidiabetic, neuroprotective, osteoprotective, anti-obesity, and anti-inflammatory effects. OA, as a natural antioxidant, plays an important role in neutralizing reactive oxygen species, which contribute to the oxidative stress that is responsible for the development of many diseases, including cancer and cardiovascular and neurodegenerative diseases. This article also presents natural sources of OA, including grapes, olives, and apples, and discusses the mechanisms of its antioxidant action, including the inhibition of lipid peroxidation and the modulation of signaling pathways related to inflammatory processes. In addition, there are research results that indicate the therapeutic benefits of OA in the treatment of diabetes and neurodegenerative diseases, as well as its potential to protect the heart, liver, and kidneys from oxidative damage. In conclusion, OA has potent antioxidant properties that can be used in the prevention and treatment of many diseases related to oxidative stress. This article also presents the possibility of increasing the bioavailability of OA through the use of nanoparticle and liposome technology.

This study investigated the antioxidant activity DPPH, ABTS, and Folin–Ciocalteu methods of betulin (compound 1) and its derivatives (compounds 2–11). Skin permeability and accumulation associated with compounds 1 and 8 were also examined. Identification of the obtained products (compound 2–11) and betulin isolated from plant material was based on the analysis of ¹H- NMR and ¹³C-NMR spectra. The partition coefficient was calculated to determine the lipophilicity of all compounds. In the next stage, the penetration through pig skin and its accumulation in the skin were evaluated of ethanol vehicles containing compound 8 (at a concentration of 0.226 mmol/dm³), which was characterized by the highest antioxidant activity. For comparison, penetration studies of betulin itself were also carried out. Poor solubility and the bioavailability of pure compounds are major constraints in combination therapy. However, we observed that the ethanol vehicle was an enhancer of skin permeation for both the initial betulin and compound 8. The betulin 8 derivative showed increased permeability through biological membranes compared to the parent betulin. The paper presents the transformation of polycyclic compounds to produce novel derivatives with marked antioxidant activities and as valuable intermediates for the pharmaceutical industry. Moreover, the compounds contained in the vehicles, due to their mechanism of action, can have a beneficial effect on the balance between oxidants and antioxidants in the body, minimizing the effects of oxidative stress. The results of this work may contribute to knowledge regarding vehicles with antioxidant potential. The use of vehicles for this type of research is therefore justified.

The present work aimed to obtain a set of oleanolic acid derivatives with a high level of cytotoxic and antioxidant activities and a low level of toxicity by applying an economical method. Oleanolic acid was alkylated with α,ω-dihalogenoalkane/α,ω-dihalogenoalkene to obtain 14 derivatives of dimer structure. All of the newly obtained compounds were subjected to QSAR computational analysis to evaluate the probability of the occurrence of different types of pharmacological activities depending on the structure of the analysed compound. All dimers were tested for cytotoxicity activity and antioxidant potential. The cytotoxicity was tested on the SKBR-3, SKOV-3, PC-3, and U-87 cancer cell lines with the application of the MTT assay. The HDF cell line was applied to evaluate the tested compounds’ Selectivity Index. The antioxidant test was performed with a DPPH assay. Almost all triterpene dimers showed a high level of cytotoxic activity towards selected cancer cell lines, with an IC₅₀ value below 10 µM. The synthesised derivatives of oleanolic acid exhibited varying degrees of antioxidant activity, surpassing that of the natural compound in several instances. Employing the DPPH assay, compounds 2a, 2b, and 2f emerged as promising candidates, demonstrating significantly higher Trolox equivalents and highlighting their potential for pharmaceutical and nutraceutical applications. Joining two oleanolic acid residues through their C-17 carboxyl group using α,ω-dihalogenoalkanes/α,ω-dihalogenoalkenes resulted in the synthesis of highly potent cytotoxic agents with favourable SIs and high levels of antioxidant activity.

Oleanolic acid, a naturally occurring triterpenoid compound, has garnered significant attention in the scientific community due to its diverse pharmacological properties. Continuing our previous work on the synthesis of oleanolic acid dimers (OADs), a simple, economical, and safe acetylation reaction was performed. The newly obtained derivatives (AcOADs, 3a–3n) were purified using two methods. The structures of all acetylated dimers (3a–3n) were determined based on spectral methods (IR, NMR). For all AcOADs (3a–3n), the relationship between the structure and the expected directions of pharmacological activity was determined using a computational method (QSAR computational analysis). All dimers were also tested for their cytotoxic activity on the SKBR-3, SKOV-3, PC-3, and U-87 cancer cell lines. HDF cell line was applied to evaluate the Selectivity Index of the tested compounds. All cytotoxic tests were performed with the application of the MTT assay. Finally, all dimers of oleanolic acid were subjected to DPPH and CUPRAC tests to evaluate their antioxidant activity. The obtained results indicate a very high level of cytotoxic activity (IC₅₀ for most AcOADs below 5.00 µM) and a fairly high level of antioxidant activity (Trolox equivalent in some cases above 0.04 mg/mL).

This paper presents the influence of acetylation on the cytotoxic and antioxidant activity of natural triterpenes. Oleanolic acid, betulin, betulinic acid and other triterpenes have been modified to improve their pharmacological properties. Acylation of the hydroxyl group at the C-3 position showed significant changes in biological activity, in particular against cancer cell lines such as HeLa, A-549, MCF-7, PC-3 and SKOV-3, with the highest IC50 results for acetyloleanolic acid (1b) and acetylbetulinic acid (4b). Docking results showed that all compounds tested demonstrated the ability to bind to pockets (C1–C5) of the p53 Y220 protein, obtaining different Vina score values. The strongest binding was observed for compound 2b in the C3 pocket (−10.1 kcal × mol−1), while in the largest C1 pocket, the best result was achieved by compound 5b (−9.1 kcal × mol−1). Moreover, antioxidant studies using the CUPRAC and DPPH tests showed significant differences in the mechanisms of action of the compounds depending on the structure. The analyses of ADMETox confirmed the favorable pharmacokinetic profile and low toxicity of most of the tested derivatives. The results suggest that acetylated triterpenes, especially 1b and 4b, have great potential as anticancer drug candidates, requiring further research on their cytotoxic activity and structural modifications.