Elsevier

Reproductive Toxicology

Volume 81, October 2018, Pages 58-63
Reproductive Toxicology

Rosmarinic acid compromises human sperm functions by an intracellular Ca2+ concentration-related mechanism

https://doi.org/10.1016/j.reprotox.2018.07.079Get rights and content

Highlights

  • Rosmarinic acid (RA) treatment decreases motility of human sperm.

  • RA inhibits capacitation and spontaneous acrosome reaction of human sperm.

  • RA reduces human sperm intracellular Ca2+ concentration ([Ca2+]i).

  • RA impairs human sperm [Ca2+]i by affecting KSPER.

Abstract

Rosmarinic acid (RA), a natural phenolic ester, is cytoprotective for male reproduction in animal models. The present study investigated the in vitro actions of RA on human sperm functions. Human sperm were exposed to 1, 10, 100, and 1000 μM RA in vitro and sperm functions were examined. The results showed that although RA did not affect human sperm viability, RA at 10–1000 μM dose-dependently reduced sperm motility, penetration ability, capacitation, and spontaneous acrosome reaction. In addition, the intracellular Ca2+ concentration ([Ca2+]i), which serve as a key regulator of sperm function, was decreased by RA (10–1000 μM) in a dose-dependent manner. Furthermore, the current of the sperm-specific potassium channel, KSPER, which is predominant for Ca2+ influx in sperm, was dose-dependently inhibited by 10–1000 μM RA. Therefore, we conclude that in vitro exposure to RA can compromise human sperm functions by decreasing sperm [Ca2+]i through the suppression of KSPER current.

Introduction

Rosmarinic acid (RA) is a phenolic ester derived from caffeic acid and (R)-(+)-3-(3,4-dihydroxyphenyl)lactic acid. RA accumulates in high amounts in many plant species, and is especially abundant in many herbs of the Lamiaceae family, such as rosemary, mint, and basil [1,2]. The numerous biological and pharmacological activities of RA that have led to many clinical applications include antioxidant, antitumor, anti-fibrosis, anti-inflammatory, antimicrobial, and anti-neurodegenerative disease activities [[1], [2], [3], [4], [5]]. In addition, RA has long been used in the food, cosmetic, and fragrance industries [[6], [7], [8]]. The pharmacology and biotechnological applications of RA have been intensively studied during the last decade.

Recent studies have reported that RA can attenuate doxorubicin-induced testicular injury and reverse the negative effects of metronidazole-induced male infertility in rats [9,10]. RA also increases sexual behavior and testosterone levels in diabetic male rats [11]. In addition, the strong antioxidant activity of RA improves sperm function and in vitro fertilizing ability after sperm cryopreservation in several animals including boar [12], bull [13], and ram [14]. These results indicate that RA acts as a cytoprotective agent for male reproduction in animal models. However, the effect of RA on human sperm remains unclear. We recently described that a Chinese herb that has similar bioactivities to RA inhibits human sperm functions by reducing sperm intracellular calcium ion concentration ([Ca2+]i) and tyrosine phosphorylation [15]. Determining the effect of RA on human sperm is essential to expand the knowledge of the clinical adverse effects of RA and to evaluate the safety of RA as a cryopreservative agents of human sperm.

In this study, we evaluated the effects of RA on the viability, motility, capacitation, and acrosome reaction processes of human sperm, which are essential for fertilization. To understand the underlying mechanism, the effects of RA on sperm [Ca2+]i, currents of the cation channel of sperm (CATSPER) and potassium channel of sperm (KSPER), and intracellular cyclic adenosine monophosphate (cAMP) were examined.

Section snippets

Semen sample collection and treatments

Semen samples were obtained by masturbation after 3–5 days of sexual abstinence. The donors (25–38 years old) had reproductive history during the preceding 2 years and normal sperm quality according to the World Health Organization (WHO) laboratory manual for the examination and processing of human semen (http://www.who.int/reproductivehealth/publications/infertility/9789241547789/en/). The collection of the samples was approved by the Institutional Ethics Committee on human subjects of Jiangxi

RA treatment affects human sperm motility

To evaluate the effects of RA on sperm viability and motility at non-capacitated and capacitated stages, we incubated human sperm in HTF medium (a non-capacitated solution) for 1 h and in HTF++ medium (a capacitated solution) for 4 h, respectively. The results showed that human sperm viability was not significantly affected by the in vitro exposure to 1–1000 μM RA either at non-capacitated or capacitated stage (Fig. 1A). In addition, RA (10, 100 and 1000 μM) exposure for 1 h to human sperm at

Discussion

The various biological and pharmacological activities have led to the use of RA clinically, in foods, in everyday chemicals, and in agricultural applications [1,2,6,24]. These environmental and/or clinical RA exposures can be ubiquitous in daily life via multiple pathways. In addition, RA is a potential cytoprotective agent for sperm cryopreservation in animal models [[12], [13], [14]]. The latter use for human sperm is unresolved since the effect of RA on human sperm is unclear. It is

Conflict of interest

The authors declare that there are no conflicts of interest.

Acknowledgements

This work was supported by the National Key Research and Development Program of China (grant number 2016YFC1000905), National Natural Science Foundation of China (grant number 81771644), Natural Science Foundation of Jiangxi, China (grant numbers 20171ACB21006 and 20161BAB204167), and the open project of National Population and Family Planning Key Laboratory of Contraceptives and Devices Research (grant number No. 2016KF07).

References (33)

  • M. Petersen

    Rosmarinic acid: new aspects

    Phytochem. Rev.

    (2013)
  • S. Nunes et al.

    Therapeutic and nutraceutical potential of rosmarinic acid-cytoprotective properties and pharmacokinetic profile

    Crit. Rev. Food Technol.

    (2017)
  • S. Habtemariam

    Molecular pharmacology of rosmarinic and salvianolic acids: potential seeds for alzheimer’s and vascular dementia drugs

    Int. J. Mol. Sci.

    (2018)
  • I. Borrás-Linares et al.

    Rosmarinus officinalis leaves as a natural source of bioactive compounds

    Int. J. Mol. Sci.

    (2014)
  • V.P. Bulgakov et al.

    Rosmarinic acid and its derivatives: biotechnology and applications

    Crit. Rev. Biotechnol.

    (2012)
  • A. Khojasteh et al.

    New trends in biotechnological production of rosmarinic acid

    Biotechnol. Lett.

    (2014)
  • Cited by (0)

    View full text