Altering the phenolics profile of a green tea leaves extract using exogenous oxidases

Tannase from Aspergillus melleus improves the antioxidant activity of green tea: purification and biochemical characterisation

“…4, we observed that the potential antioxidant activity of green tea in the presence of tannase had no significant changes following 40 min of hydrolysis. Verloop et al (2015) report that catechins are one of the most numerous components found in green tea. There are several different types of catechins, such as epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), epicatechin (EC) gallocatechin (GC) and catechin (C).…”

A tandem mass spectrometry method based on selected ions detects low‐abundance phenolics in black tea – theatridimensins as products of the oxidative cascade

“…To understand the oligomerization reactions that occur in the formation of black tea, a model system has recently been used with only a limited number of precursors, TF with epicatechin (EC), and a single oxidase with well‐defined activity, tyrosinase . TF is the oligomerization product of EC and epigallocatechin.…”

“…The formation of TNQ, however, needs two oxidation steps: an oligomerization into TF, and a rearrangement of TF into TNQ. Other two‐step‐oxidation products via TF are formed by a second oligomerization step, when EC‐quinone via its B‐ring couples to the benzotropolone ring of TF, yielding the trimeric catechin theatridimensin (T3D) . Alternatively, the EC‐quinone B‐ring can attack the aromatic ring in the interflavanic configuration of TF, upon which a TS‐type cross‐link is formed, yielding the trimeric catechin TFsEC (the ‘s’ indicating the TS‐type of oligomerization) .…”

Dereplication of plant phenolics using a mass‐spectrometry database independent method

“…Their importance is closely related to their antioxidant properties. Many well‐known biological activities such as antimicrobial, antitumor, and cardiovascular benefits are associated with the regular ingestion of phenolics …”

“…Many well-known biological activities such as antimicrobial, antitumor, and cardiovascular benefits are associated with the regular ingestion of phenolics. [12][13][14] MFQL files with molecular structure restrictions were created for the main classes of phenolics and used for dereplication. The method was tested on well-studied plants extracts.…”