White Tea as a Promising Antioxidant Medium Additive for Sperm Storage at Room Temperature: A Comparative Study with Green Tea Ta ̂ nia R. Dias, Marco G. Alves, Gonc ̧ alo D. Toma ́ s, Sílvia Socorro, Branca M. Silva,* and Pedro F. Oliveira* CICS - UBI - Health Sciences Research Centre, University of Beira Interior, 6201-506 Covilhã , Portugal ABSTRACT: Storage of sperm under refrigeration reduces its viability, due to oxidative unbalance. Unfermented teas present high levels of catechin derivatives, known to reduce oxidative stress. This study investigated the effect of white tea (WTEA) on epididymal spermatozoa survival at room temperature (RT), using green tea (GTEA) for comparative purposes. The chemical profiles of WTEA and GTEA aqueous extracts were evaluated by 1 H NMR. (-)-Epigallocatechin-3-gallate was the most abundant catechin, being twice as abundant in WTEA extract. The antioxidant power of storage media was evaluated. Spermatozoa antioxidant potential, lipid peroxidation, and viability were assessed. The media antioxidant potential increased the most with WTEA supplementation, which was concomitant with the highest increase in sperm antioxidant potential and lipid peroxidation decrease. WTEA supplementation restored spermatozoa viability to values similar to those obtained at collection time. These findings provide evidence that WTEA extract is an excellent media additive for RT sperm storage, to facilitate transport and avoid the deleterious effects of refrigeration. KEYWORDS: sperm, Camellia sinensis, white tea, green tea, epigallocatechin-3-gallate, reactive oxygen species, antioxidants ■ INTRODUCTION Tea (Camellia sinensis (L.)) is one of the world’s most widely consumed beverages, and its medicinal properties have been widely explored. 1 It can be classi fied in three types: unfermented (green and white teas), partially fermented (oolong tea), and completely fermented (black tea). 2 To produce green tea (GTEA), freshly harvested leaves are steamed to inactivate polyphenol oxidase enzyme and then rolled and dried. Its chemical composition is very similar to that of the fresh tea leaf. 1 White tea (WTEA) is exclusively prepared from young tea leaves or buds, harvested before being fully opened. The tea materials are picked and immediately sent to be steamed and dried to prevent oxidation, frequently followed by polymerization. 3 Unfermented teas are known to have high polyphenolic content, mainly catechin derivatives, (-)-epi- gallocatechin 3-gallate (EGCG) being the most abundant and powerful antioxidant. 4 With respect to processing, there are very little differences between green and white teas, although several papers suggest that WTEA presents higher levels of antioxidants than GTEA. 5 Recently, antioxidant components have aroused great interest due to their ability to minimize the deleterious effects of reactive oxygen species (ROS) on a number of biological and pathological processes. 6 ROS are necessary for the normal physiological function of sperm, 7 although their concentration must be kept under strict control to avoid deleterious effects, such as damage to cell structures: lipids and membranes, proteins, and DNA. 8 It has been reported that ROS overproduction results in oxidative stress (OS), which is related to several problems that may end up in male subfertility or infertility. 9 In fact, spermatozoa are particularly vulnerable to such stress because ROS readily attack the polyunsaturated fatty acids (PUFA) of the cells membrane, initiating a self-propagating chain reaction. End- products of these lipid peroxidation reactions, such as malondialdehyde (MDA), are especially dangerous for cell viability. 10 Therefore, there is a growing interest in enlightening the role of ROS formation in sperm as they are responsible for lower sperm quality in freshly collected semen and poor quality of sperm after processing for usage in reproductive technologies, such as artificial insemination (AI), in vitro fertilization (IVF), or cryopreservation. 11 The maintenance of mammalian sperm at room temperature (RT) for short-term periods is advantageous as the storage of sperm in a refrigerated environment induces a rapid decline in its viability. 12 Establishment of optimal composition for sperm storage is of extreme relevance, as these cells are highly dependent on the supply of exogenous substrates and, due to their high metabolic rates, produce elevated amounts of ROS. 12 The addition of GTEA polyphenols has proven to be of great significance on frozen-thawed spermatozoa motility. 13 Here, we aimed to investigate the possible protective effect of WTEA extract on epididymal spermatozoa survival at RT, using GTEA as a comparison reference. 14 For that purpose, the chemical profiles of WTEA and GTEA aqueous extracts were determined by using 1 H NMR as well as the antioxidant potential of storage media containing these extracts. Furthermore, the effect of both extracts on epididymal spermatozoa maintenance at RT during 24, 48, and 72 h was evaluated by determining the spermatozoa antioxidant potential, lipid peroxidation, and viability during that time frame. Received: June 5, 2013 Revised: December 28, 2013 Accepted: December 28, 2013 Published: December 28, 2013 Article pubs.acs.org/JAFC © 2013 American Chemical Society 608 dx.doi.org/10.1021/jf4049462 | J. Agric. Food Chem. 2014, 62, 608-617