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.

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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 mg/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.

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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.