Effect of oxamic analogues on functional mice sperm parameters

Figures & data

Table 1. Inhibition of the oxamate derivatives on glycolytic enzymes from sperm mice extracts..

			IC50 (µM)			GAPDS	HK1S
Compound	R1	R2	LDH-C4	GAPDS	HK1S	ratio^1 LDH-C4	ratio^1 LDH-C4
N-ethyl oxamic acid (NEOX)		H	8.00	62.40	5300	8	663
N-propyl oxamic acid (NPOX)		H	24.60	173.10	117,380	7	4772
N-butyl oxamic acid (NBOX)		H	25.40	561.00	99,160	22	3904
N-ethyl oxamate ethyl ester (NEOXet)			20.4	475.4	5330	23	261
N-propyl oxamate ethyl ester (NPOXet)			100.4	669.8	70,260	7	700
N-butyl oxamate ethyl ester (NBOXet)			22.0	660.1	161,980	30	7363

IC₅₀: half maximal inhibitory concentration; LDH-C4: lactate dehydrogenase-C4; GAPDS: glyceraldehyde-3-phosphate dehydrogenase; HK1S: hexoquinase; ¹ Selectivity for LDH-C4 (fold).

Figure 1. Effect of N-alkyl oxamate prodrugs on the parameters of mouse sperm motility. Each graph represents percentage of motile sperm after 30 min of incubation in absence and presence of different concentrations of N-alkyl oxamate prodrugs. NEOXet: N-ethyl oxamate ethyl ester (□), NPOXet: N-propyl oxamate ethyl ester (▴), and NBOXet: N-butyl oxamate ethyl ester (▾). (A) total motility (100% means 45.3%), (B) progressive motility (100% means 13.4%), (C) average path velocity (VAP) (100% means 69.9 µm/s), (D) straight line velocity (VSL) (100% means 44.9 µm/s), (E) track speed (VCL) (100% means 141 µm/s), (F) lateral amplitude (ALH) (100% means 10.06 µm), and (G) beat frequency (BCF) (100% means 32.23 Hz). Values are the mean ± SEM, n = 3. (a) means significant difference and (b) means not significant difference. Data analysis was performed using Dunnett’s multiple comparison test, p < 0.05.

Figure 2. Acrosome reaction in mouse sperm exposed to N-alkyl oxamates prodrugs after capacitating. Bars represent percentage of mouse sperm with induced acrosome reaction with 10 µM calcium ionophore A23187 after 30 min of incubation in absence and presence of N-alkyl oxamate prodrugs. ▪ control, ▪ N-ethyl oxamate ethyl ester (NEOXet), ▪ N-propyl oxamate ethyl ester (NPOXet), ▪ N-butyl oxamate ethyl ester (NBOXet). Values are expressed as mean ± SEM (n = 3). Data analysis was performed using Dunnett’s multiple comparison test, p < 0.05. *: means significant difference.

Table 2. Effect of N-alkyl oxamate prodrugs on the mice sperm viability after 30 min incubation.

	Concentration (mM)
Prodrug	0	15	30	45
N-ethyl oxamate ethyl ester (NEOXet)	76.05 ± 4.45	51.45 ± 10.72*	48.44 ± 7.21*	33.18 ± 0.55*
N-propyl oxamate ethyl ester (NPOXet)		52.19 ± 7.57*	48.14 ± 11.01*	23.03 ± 8.42*
N-butyl oxamate ethyl ester (NBOXet)		45.78 ± 0.31*	46.90 ± 9.33*	18.46 ± 1.35*

Values are expressed as mean ± SEM (n =3). *: means significant difference.

Figure 3. In vivo effect of N-butyl oxamate ethyl ester (NBOXet) on motility. A) Changes on mouse sperm motility after one week of administration with a single dose of NBOXet and (B) kinematic parameters of mice sperm from vas deferens. ▪ control, ▪ 200 mg/kg; average path velocity (VAP), straight line velocity (VSL), track speed (VCL) (µm/s), lateral amplitude (ALH) (µm), beat frequency (BCF) (Hz). Comparisons were performed using Student t test. *: means significant difference, p < 0.05.