Orange thyme: Phytochemical profiling, in vitro bioactivities of extracts and potential health benefits

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The use of orange thyme as food, condiments and infusions has health benefits.

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Phytochemical characterization of hydroethanolic and aqueous extracts was performed.

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Orange thyme extracts present neuroprotective, anti-aging and antioxidant activity.

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Orange thyme extracts present high anti-inflammatory activity with no cytotoxicity.

Orange thyme (Thymus fragrantissimus) is becoming widely used in food as a condiment and herbal tea, nevertheless its chemical composition and potential bioactivities are largely unknown. Thus the objective of this work is to obtain a detailed phytochemical profile of T. fragrantissimus by exhaustive ethanolic extraction and by aqueous decoction mimicking its consumption. Extracts showed high content in rosmarinic acid, luteolin-O-hexuronide and eriodictyol-O-hexuronide; these were the main phenolic compounds present in orange thyme accounting for 85% of the total phenolic compounds. Orange thyme extracts presented high scavenging activity against nitric oxide and superoxide radicals. Both extracts presented significant inhibitory effect of tyrosinase activity and moderate anti-acetylcholinesterase activity. Both extracts showed a good in vitro anti-inflammatory activity and a weak anti-proliferative/cytotoxic activity against Caco-2 and HepG2 cell lines supporting its safe use. Orange thyme is a very good source of bioactive compounds with potential use in different food and nutraceutical industries.

Polyphenol composition and biological activity of Thymus citriodorus and Thymus vulgaris: Comparison with endemic Iberian Thymus species

The polyphenol compositions of Thymus × citriodorus and Thymus vulgaris extracts as obtained by exhaustive hydroethanolic (HE) extraction and aqueous decoction (AD) were compared. In addition, their compositions and bioactivities were compared to those of Thymus pulegioides and Thymus mastichina, grown under the same edaphoclimatic conditions, and Thymus carnosus. Rosmarinic acid was the most abundant polyphenol followed by luteolin-hexuronide, salvianolic acids I and K. Cluster analysis suggests a similarity of the polyphenol composition of T. citriodorus and T. vulgaris. A significant antioxidant activity was observed and correlated with their polyphenol levels. The same being observed for the higher anti-proliferative activity/cytotoxicity of HE extracts on Caco-2 and HepG2 cells as compared to AD extracts. Significant association between the total phenolic compounds with the anti-proliferative activity, for both cell lines, was observed. These results support the importance of salvianolic acids levels in Thymus extracts and their in vitro anti-proliferative/cytotoxic activities.