Spilanthes acmella ethanolic flower extract: LC-MS alkylamide profiling and its effects on sexual behavior in male rats

According to Indian Systems of Medicine, Spilanthes acmella (L.) Murr. (Family- Asteraceae), is considered effective in the treatment of sexual deficiencies especially due to aging. In the present study, characterization of ethanolic extracts of the Spilanthes acmella flower and its effect on general mating pattern, penile erection and serum hormone levels of normal male Wistar albino rats were investigated and compared with sildenafil citrate. In-vitro nitric oxide release was also investigated in human corpus cavernosum cell line. N-alkylamides are a promising group of naturally occurring bio-actives in Spilanthes spp. Therefore, N-alkylamide profiling of ethanol extract of Spilanthes acmella flowers was performed, using a gradient reversed phase high performance liquid chromatography/electrospray ionization ion trap mass spectrometry (HPLC/ESI-MS) method on an embedded polar column. MS1 and MS2 fragmentation data were used for identification purposes. The extracts (50, 100 and 150 mg/kg body weight/day) and sildenafil citrate (5mg/kg) were administered orally for 28 days. The behavioral parameters were observed at day 0, 15, 28 and after a lapse of 7 and 14 days of discontinuance of drug treatment. Five N-isobutylamides, one 2-methylbutylamide and one 2-phenylethylamide were tentatively identified. The orally administered extract had a dose dependent effect on mounting frequency, intromission frequency and ejaculation frequency. A dose dependent effect was also observed on the FSH, LH and testosterone serum levels. The aphrodisiac potential of an ethanolic Spilanthes acmella extract was demonstrated in-vitro and in-vivo. Study lends support to the traditional utilization of S. acmella as a sexual stimulating agent