Study question

Does the addition of procyanidine to the semen of infertile men result in a higher progressive motility after 3 hours of incubation as compared with no addition of procyanidine?

Summary answer

In vitro addition of procyanidine to the semen of infertile men results in a significantly higher progressive motility after 3 hours of incubation as compared with no addition of procyanidine.

What is known already

Several studies on sperm physiology and fertilizing capacity have shown a beneficial effect of oral antioxidants. Procyanidine is a natural antioxidant, which is much stronger than vitamin C and E and has many applications in the food, agriculture, pharmaceutical and cosmetic industry. Its in vitro effect, however, on human spermatozoa has not been studied yet.

Study design, size, duration

A prospective in vitro trial was performed in the semen of 25 infertile men. Semen samples were divided in two aliquots, in which addition of procyanidine (procyanidine group) or not (control group) took place. Semen analysis and sperm DNA fragmentation index (DFI) were performed at baseline (prior to the division of semen samples), after 3 hours of incubation at 37oC and after sperm cryopreservation and thawing. The primary outcome measure was progressive sperm motility after three hours of incubation. Secondary outcome measures were total motility, sperm vitality, morphology and DFI. The study was designed to detect a difference of 3% in progressive sperm motility between the two groups compared.

Participants/materials, setting, methods

Semen samples from 25 infertile men were collected by masturbation after an abstinence period of 3-5 days. Male infertility was diagnosed if at least one semen parameter was abnormal in two consecutive semen analyses, according to the WHO 2010 criteria. DFI was assessed by the TUNEL method. Results are expressed as median with interquartile range (IR), unless stated otherwise.

Main results and the role of chance

The mean (SD) age of included patients was 38.3±4.3 years, while body mass index (BMI) was 26.1±3.2 kg/m2. Moreover, the proportion [95% confidence interval (CI)] of smokers was 52% (31.8-71.6), while that of alcohol consumers was 24% (10.5-45.8). An increase in sperm DFI was observed after 3 hours of incubation both in the procyanidine [16% (7) vs. 18% (7), p<0.001] and the control groups [16% (7) vs. 18% (8), p<0.001]. In both the procyanidine and the control groups a decrease in sperm vitality [82% (10) vs. 78% (10), p=0.002 and 82% (10) vs. 80% (13), p=0.032], total motility [50% (10) vs. 46% (17), p<0.001 and 50 (10) vs. 45 (22) p<0.001] and progressive motility [42% (11) vs. 41% (17), p=0.003 and 42% (11) vs. 39% (21), p<0.001] was observed, respectively. The decrease in progressive motility [-4% (14) vs. -6% (15), p<0.001] and total motility [-5% (14) vs. -9% (17), p< 0.001], was lesser in the procyanidine compared with the control group. A decrease in sperm morphology was observed after 3 hours of incubation only in the control group [2% (2) vs. 1% (2), p=0.009]. In both the procyanidine and the control group, after thawing of cryopreserved semen samples, a decrease in sperm vitality [78% (10) vs. 46% (18), p=0.003 and 80% (13) vs. 45% (19), p<0.001], morphology [2% (2) vs. 0.5% (1.75), p<0.001 and 1% (2) vs. 0.5% (1.75), p<0.001], total motility [46% (17) vs. 11% (14), p<0.001 and 45% (22) vs. 11% (14), p<0.001] and progressive motility [41% (17) vs. 7% (10), p<0.001 and 39% (21) vs. 6% (13), p<0.001] was observed, respectively. In addition, sperm DFI was increased both in the procyanidine [18% (7) vs. 25% (10), p<0.001] and in the control [18% (8) vs. 27% (9), p<0.001] groups. However, the increase in sperm DFI was larger in the control as compared with the procyanidine group [9% (4) vs. 3% (7), p=0.005].

Limitations, reasons for caution

In the current study, a single dose of procyanidine was added to semen samples, while its effect was assessed three hours after addition. A 3-hour incubation period was selected since it represents the average time between ovum pick up (OPU) and intracytoplasmic sperm injection (ICSI). Apparently, the results of the current study are valid only for the concentration of procyanidine added and the incubation period examined. Different concentrations of procyanidine and/or incubation periods might be associated with different effects on sperm than those observed in the current study.

Wider implication of findings

The findings of the current study should be further optimized by evaluating the effect of different procyanidine concentrations at different time intervals in prepared and unprepared samples. If a beneficial effect of in vitro procyanidine addition on sperm motility and DFI is confirmed in further in vitro trials, this may justify its evaluation in semen preparation for intra-uterine insemination (IUI) or in vitro fertilization (IVF)/ICSI as well as in sperm cryopreservation. Moreover, its in vivo use in infertile men with the aim to enhance sperm quality might warrant evaluation.


Sperm analysis, DNA Fragmentation Index, cryopreservation, antioxidants, procyanidine.

Study funding/competing interest

The study was funded by a scholarship from the Ministry of Higher Education, The Arab Republic of Egypt.

Trial registration number