The characterization of compounds with antioxidant activity is of great interest due to their ability to reduce reactive oxygen species production and, therefore, prevent some age-related diseases. Its antioxidant capacity can be analyzed by different methods both in vitro and in vivo. Caenorhabditis elegans is an in vivo model widely used in ageing research. Until now, available tests analyze functional effects in the worms, so the antioxidant activity of the compound is indirectly monitored. We have developed a simple and a reliable method to quantify internal antioxidant activity in vivo. To validate this method, we analyzed an aqueous green tea extract and two other compounds with a well-known antioxidant activity and without this activity. The results obtained (EC₅₀ green tea = 21.76 ± 1.28 µg/mL; EC₅₀ positive control = 8.50 ± 0.33 µg/mL; negative control EC₅₀ > 500 µg/mL) can help in the design of further in vivo experiments. Thus, our method can be used as a previous screening capable of reducing the gap between in vitro and in vivo assays.

Aging-related diseases can be triggered by multiple factors such as oxidative stress. Oxidative stress is an imbalance between free radicals and antioxidants, so today, compounds capable of reducing or neutralizing free radicals are being studied for a therapeutic use. Origanum vulgare L. is a traditional medicinal plant used for a wide number of health problems due to its antimicrobial, carminative and antioxidant activities. However, when administered orally, gastrointestinal digestion can modify some of therapeutical properties. To avoid this, two different solid oral formulations have been designed for an O. vulgare extract evaluating their antioxidant behaviours in vitro and in vivo after a simulation of gastrointestinal digestion. The results showed that the divided powder has a lower antioxidant activity both in vitro and in vivo than the encapsulated extract. The quantitative difference of polyphenols found on HPLC-DAD (especially luteolin, apigenin and caffeic acid) may explain the differences in pharmacological activity. Thus, we propose that the best form to administrate O. vulgare extracts to maintain the antioxidant properties is the encapsulated form, that is, two capsules of 250 mg of a hydroalcoholic extract of O. vulgare with a minimum of 33 % of rosmarinic acid as a daily dose.

Alzheimer’s disease is a neurodegenerative disease characterized by progressive memory loss and cognitive impairment due to a severe loss of cholinergic neurons in specific brain areas. It is the most common type of dementia in the aging population. Although many anti-acetylcholinesterase (AChE) drugs are already available on the market, their performance sometimes yields unexpected results. For this reason, research works are ongoing to find potential anti-AChE agents both from natural and synthetic sources. In this study, 90 extracts from 30 native and naturalized medicinal plants are tested by TLC and Ellman’s colorimetric assay at 250, 125 and 62.5 μg/mL in order to determine the inhibitory effect on AChE. In total, 21 out of 90 extracts show high anti-AChE activity (75–100% inhibition) in a dose-dependent manner. Among them, ethanolic extract from aerial parts of O. vulgare ssp. vulgare shows an IC50 value 7.7 times lower than galantamine. This research also establishes the chemical profile of oregano extract by TLC, HPLC-DAD and LC-MS, and twenty-three compounds are identified and quantified. Dihydroxycinnamic acids and flavonoids are the most abundant ones (56.90 and 25.94%, respectively). Finally, total phenolic compounds and antioxidant properties are quantified by colorimetric methods. The total phenolic content is 207.64 ± 0.69 µg/mg of extract. The antioxidant activity is measured against two radicals, DPPH and ABTS. In both assays, the oregano extract shows high activity. The Pearson correlation matrix shows the relationship between syringic acids, a type of dihydroxybenzoic acid, and anti-AChE (r² = −0.9864) and antioxidant activity (r² = 0.9409 and 0.9976). In conclusion, the results of this study demonstrate promising potential new uses of these medicinal herbs for the treatment of Alzheimer’s. Origanum vulgare ssp. vulgare and syringic acids, which have anti-AChE activity and beneficial antioxidant capacity, can be highlighted as potential candidates for the development of drugs for the treatment of Alzheimer’s disease and other diseases characterized by a cholinergic deficit.

Background: Non-insulin-dependent diabetes mellitus, or type 2 diabetes, is one of the diseases of greatest concern worldwide, and research into natural compounds that are capable of regulating glycemia and insulin resistance is therefore gaining importance. In the preclinical stages, Caenorhabditis elegans is considered a promising in vivo model for research into this disease. Most studies have been carried out using daf-2 mutant strains and observing changes in their phenotype rather than directly measuring the effects within the worms. Methods: We evaluated the in vitro α-glucosidase inhibition of two oral formulations of Origanum vulgare before and after a simulated gastrointestinal digestion process. After confirming this activity, we developed a method to measure α-glucosidase inhibition in vivo in the C. elegans wild-type strain. Results: The crude extract showed a similar IC50 value to that of acarbose (positive control), before and after gastrointestinal digestion. Formulation 1 also showed no differences with the positive control after digestion (111.86 ± 1.26 vs. 110.10 ± 1.00 µL/mL; p = 0.282). However, formulation 2 showed a higher hypoglycemic activity (59.55 ± 0.85 µL/mL; p < 0.05). The IC50 values obtained in the in vivo assays showed results that correlated well with the in vitro results, so the proposed new method of direct quantification of the in vivo activity seems suitable for directly quantifying the effects of this inhibition without the need to measure changes in the phenotype. Conclusion: A novel, simple and reliable method has been developed to directly determine pharmacological activities in an in vivo model of wild-type C. elegans. This allows the hypoglycemic activity to be directly attributed to in vivo treatment without quantifying phenotypic changes in mutant strains that may arise from other effects, opening the door to a simple analysis of in vivo pharmacological activities.

Background: One of the main diseases of worldwide concern is non–insulin dependent Diabetes mellitus. 90-95% of patients with diabetes suffers from Type II diabetes, a metabolic diabetes whose prevalence is increasing in the world.Given the current prevalence of diabetes type II in society, research of natural compounds able to regulate glycaemia and insulin–resistance is nowadays covering importance, as alternative or co–adjuvant treatment to existing hypoglycaemic medicines. In pre–clinical steps of research, C. elegans is considered a promising in vivo model for the study of the molecular mechanism of glucose as part of anti–diabetic bioactivity.Most of the studies of insulin resistance with this in vivo model are carried out by using mutant strains such as daf-2 and the effects of the compounds are attributed a posteriori, after a physiological response of the worms rather than directly measuring preservation of activity inside the worm. Methods: The in vitro α-glucosidase inhibition of two oral formulations with Origanum vulgare extract before and after a simulated process of gastrointestinal digestion was evaluated. After confirming the in vitro activity, the α-glucosidase inhibition was tested in vivo through the new method proposed. Results: The crude extract showed an IC50 value similar to acarbose (positive control), before and after the gastrointestinal digestion. The encapsulated extract (111.86±1.25 µg/mL) did not present statistical differences with the positive control (110.10±1.15 µg/mL) after digestion. However, the powder formulation showed the highest hypoglycaemic activity (59.55±0.85 µg/mL).In vivo, the IC50 values showed similar profile than in vitro. Conclusion: A new simple and reliable method has been developed to determine pharmacological activities inside in vivo model C. elegans.The method has been evaluated with a hydroalcoholic extract of O. vulgare. The method is accurate and valid for the quantification of the inhibition of in vivo, allowing the direct attribution of this in vivo hypoglycaemic activity to the treatment. In addition, it opens the door to further research into in vitro pharmacological activities that require an in vivo counterpart.