Table 2.

Effect of endogenous non-enzymatic antioxidants on male fertility

Antioxidant	Study type	Specie	Dose used	Outcome	Reference
GSH	In-vitro	Donkey	0, 2, 4, 6, 8, 10 mM	Significantly higher motility & kinematic parameters Higher sperm viability	[59]
	In-vivo	Human	600 mg	Significantly improved fertility	[60]
Reduced GSH & SOD	In-vitro	Bull	GSH: 5, 7.5 mM SOD: 50, 100 U/mL	Improved total and progressive motility parameters	[61]
Cysteine	In-vivo	Human	600 mg	Significantly improved sperm count and motility Significantly decreased abnormal morphology DNA fragmentation and protamine deficiency	[63]
	In-vitro	Human	1.0 mg/mL	Significantly improved sperm function and motility Significantly decreased ROS production	[64]
		Buffalo	0.0, 0.5, 1.0, 2.0, 3.0 mM	Improved antioxidant status, freeze-thaw quality, and in-vivo fertility	[65]
Cysteine & SOD	In-vitro	Chicken	5 mM 200 U/mL	Prevented the reduction in motility, viability, and mitochondrial membrane potential Protected sperm against apoptotic changes	[66]
Cysteine & Erythioneine	In-vitro	Ram	0, 1, 2, 4 mM	Improved freeze-thaw sperm motility and mitochondrial activity	[67]
Vitamin C	In-vivo	Human	5, 10, 20, 60, 250 mg/d	Reduced oxidative DNA damage of sperm	[68]
			50, 100, 200, 400, 800, 1,000, 2,000, 4,000 μg	Improved sperm motility and viability through reduced ROS production	[73]
			0, 200, 1,000 mg/d	Improved sperm quality	[69]
			1,000 mg/d	Significant rise in sperm count, sperm motility, and sperm with normal morphology	[70]
			500 mg/d	Improved sperm motility and morphology	[71]
		Rat	25 mg/kg/d	Protective role on cyclophosphamide-induced testicular dysfunction Alleviates the cyclophosphamide-induced OS	[72]
			0.88 mg/kg	Higher sperm motility, viability, and count	[155]
Vitamin E	In-vivo	Chicken	0, 20, 40, 80, 160 mg/kg	Higher sperm viability and motility (40–160 mg/kg) Higher sperm concentration (80 mg/kg)	[44]
			200 mg/kg diet	Increased both sperm count and motility Reduced percentage of dead sperm	[78]
		Human	600 mg/d	Significant improvement in in-vitro sperm function	[75]
			100 mg/d	Significantly higher sperm motility Significantly decreased MDA levels	[77]
Vitamins C & E	In-vivo	Human	1,000 mg/d 800 mg/d	Increased ejaculate volume, sperm count, and motility	[81]
			1,000 mg/d	Markedly reduced DNA-fragmented sperm	[82]
	In-vitro	Human	10 mM	Minimum improvement in sperm motility	[31]
Vitamins C & E, CAT, Hypotaurine, Cysteine, GSH	In-vitro	Human	0.2 and 1 mM 2,600 U/mL 1 & 10 mM 1 & 10 mM 1 & 10 mM	Protects against OS	[83]
Vitamins C & E, GSH	In-vitro	Human	200 mg, 200 mg, 400 mg	Reduced OS	[84]
Vitamins C & E, Urate, Cysteine	In-vitro	Human	300, 600 μM 30, 60 μM 200, 400 μM 5, 10 μM	Improved sperm DNA integrity	[74]
Mesterolone & Vitamin C	In-vivo	Human	50 mg 200 mg	No improvement in male fertility	[86]
Cysteine, Vitamin A, & Vitamin E	In-vivo	Human	600 mg/d 30 and 180 mg/d	Neutralized the ROS and improve sperm count No effect on sperm motility	[85]
Selenium	In-vivo	Human	100 μg/d	Significant rise in plasma selenium concentration and sperm motility	[156]
			400 U/d 200 μg/d	Significantly higher sperm motility, viability, and fertility	[87]
			400 mg/d 225 μg/d	Significantly improved sperm motility Significantly decreased MDA levels	[76]
Rebamipide	In-vitro	Human	10, 30, 100, 300 μM	Decreased ROS level and LPO No effect on sperm viability	[80]
Taurine	In-vitro	Sheep	0, 10, 20, 40, 80, 100 mM	Reduced LPO and improved semen parameters	[93]
		Cat	50 mM	Higher sperm motility, Reduced abnormal sperms with sperm defects	[94]
		Stallion	70, 100 mM	Improved sperm survival	[95]
		Donkey	0, 20, 40, 60 mM	Significantly improved sperm motility	[96]
		Hamster	0, 2×10−3, 2×10−4, 2×10−5 M	Improved motility and promote capacitation	[90]
Hypotaurine	In-vitro	Hamster	10 mM	Restore sperm motility and viability	[92]
Taurine & Hypotaurine	In-vitro	Rabbit	0.5 mM	Reduced LPO and restored motility	[91]
Taurine & Trehalose	In-vitro	Cattle Bull	50 mM 100 mM	Significantly improved freeze-thaw motility, viability, and plasma membrane integrity	[97]
		Buffalo Bull	50 mM 100 mM	Improved motility, viability, and membrane integrity Low numbers of capacitated sperm	[88]
Taurine, QR, & GSH	In-vitro	Ram	40 mM, 5 μg/mL, 5 mM	Reduced LPO Improved freeze-thaw semen quality	[98]
CoQ10	In-vivo	Human	200 mg/d	Improved sperm concentration, progressive motility, total motility, and semen antioxidant status Reduced ROS level and SDF percentage	[100]
		Stallion	1 gm/d	Improved semen quality	[110]
	In-vivo & In-vitro	Human	5, 50 μM 60 mg	Improved sperm motility and fertilization rate	[157]
		Buffalo bull	30 Mm	Improved sperm parameters and fertility	[105]
		Rooster	0, 1, 2, 5, 10 μM	Significantly higher total sperm, progressive motilities, membrane functionality, viability, and mitochondria active potential Reduced LPO	[104]
		Buck	0, 0.5, 1, 1.5 μM	Improved sperm motility, viability, and plasma membrane functionality	[106]
		Giant grouper	0, 25, 50, 100 μM	Improved total sperm motility, fertilization rate, and reduced DNA fragmentation	[103]
		Boar	-	Increase the sperm characteristics and prolong the survival of liquid storage of sperm	[108]
		Stallion	40 & 80 μg/mL	No notable effect of semen quality	[109]
CoQ10 & L-carnitine	In-vivo	Rat	10 mg/kg/d 350 mg/kg/d	Significantly improved sperm quality and hormonal profile by weakening the high and oxidized LDL	[102]
CoQ10 & Ellagic acid	In-vitro	Ram	0.5 μM 0.25 mM	Higher total sperm, progressive motility, and viability No effect of sperm antioxidant level	[107]

GSH, glutathione; SOD, superoxide dismutase; BSA, bovine serum albumin; LPO, lipid peroxidation; ROS, reactive oxygen species; OS, oxidative stress; MDA, malondialdehyde; QR, quercetin; Q10, coenzyme; SDF, sperm DNA fragmentation; LDL, low density lipoprotein.