Erectogenic and Aphrodisiac Effects of Butea frondosa Koenig ex Roxb. in Rats: Involvement of Enzyme Inhibition

Abstract

Butea frondosa Koenig ex Roxb. (BF) is traditionally used to manage male sexual disorders including erectile dysfunction (ED). Methanol extract of BF (bark) inhibited Rho-kinase 2 (ROCK-II) enzyme activity in vitro with an IC50 of 20.29 ± 1.83 μ g/mL. The relaxant effect of methanol extract of BF (MEBF) was studied on phenylephrine precontracted corpus cavernosum smooth muscle (CCSM) isolated from young rats. The effect of MEBF treatment on sexual behaviour of both young (5 month) and aged (24 month) rats was also studied in addition to the influence on smooth muscle, collagen (collagen-I and -III) level in penis, and sperm characteristics of young and aged rats. MEBF relaxed CCSM up to 21.77 ± 2.57% and increased sexual behavior of young and aged rats. This increase in sexual function could be attributed to ROCK-II inhibition and increase in ratio of smooth muscle to collagen level in rat penile tissue. Increased sperm production and decreased defective sperms in young and aged rats corroborate the usefulness of Butea frondosa in male infertility in addition to ED.

Figure 1

Percent inhibition of ROCK-II by Y-27672 and MEBF at different concentrations. Value is presented as mean ± standard deviation.

Figure 2

Effect of vehicle, MEBF, and sildenafil on isolated rat corpus cavernosum smooth muscle (CCSM) at different concentrations. *P < 0.05. MEBF/sildenafil versus vehicle. n = 6.

Figure 3

Transverse section (TS) of penile tissue of Wistar rat. TU: tunica albuginea, CC: corpus cavernosum, CS: corpus spongiosum, and U: urethra.

Figure 4

Masson's trichrome staining showing smooth muscle (pink) and collagen (blue) level in CCSM of rat at a magnification of 200x. MEBF treatment increased smooth muscle level in CCSM of young rats, and the effect was better than that of sildenafil. Smooth muscle level decreased in aged rat CCSM, and both MEBF and sildenafil treatment increased smooth muscle level significantly, with the effect of MEBF being more pronounced. Picrosirius red staining showing collagen-III (green) and collagen-I (red orange/yellow) level in CCSM of rat at a magnification of 100x. Collagen-III level was more prominent in CCSM of aged rats in comparison to young rats. Treatment of MEBF and sildenafil decreased collagen-III level.

Figure 5

Proposed mechanism of action of MEBF with regard to sexual behavior, sperm characteristics, smooth muscle and collagen level. Solid arrows represent stimulation and dotted arrows represent inhibition.