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. 2017;26(3):258-265.
doi: 10.1159/000464363. Epub 2017 Feb 22.

Effects of Root Extracts of Eurycoma Longifolia Jack on Corpus Cavernosum of Rat

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Free PMC article

Effects of Root Extracts of Eurycoma Longifolia Jack on Corpus Cavernosum of Rat

Bae Huey Tee et al. Med Princ Pract. .
Free PMC article

Abstract

Objective: This study was conducted to investigate the mechanisms of action of Eurycoma longifolia in rat corpus cavernosum.

Materials and methods: Tincture of the roots was concentrated to dryness by evaporating the ethanol in vacuo. This ethanolic extract was partitioned into 5 fractions sequentially with hexane, dichloromethane (DCM), ethyl acetate, butanol, and water. The corpus cavernosum relaxant activity of each fraction was investigated. The DCM fraction which showed the highest potency in relaxing phenylephrine-precontracted corpora cavernosa was purified by column chromatography. The effects of the most potent DCM subfraction in relaxing phenylephrine-precontracted corpora cavernosa, DCM-I, on angiotensin I- or angiotensin II-induced contractions in corpora cavernosa were investigated. The effects of DCM-I pretreatment on the responses of phenylephrine-precontracted corpora cavernosa to angiotensin II or bradykinin were also studied. An in vitro assay was conducted to evaluate the effect of DCM-I on angiotensin-converting enzyme activity.

Results: Fraction DCM-I decreased the maximal contractions (100%) evoked by angiotensin I and angiotensin II to 30 ± 14% and 26 ± 16% (p < 0.001), respectively. In phenylephrine-precontracted corpora cavernosa, DCM-I pretreatment caused angiotensin II to induce 82 ± 27% relaxation of maximal contraction (p < 0.01) and enhanced (p < 0.001) bradykinin-induced relaxations from 47 ± 8% to 100 ± 5%. In vitro, DCM-I was able to reduce (p < 0.001) the maximal angiotensin-converting enzyme activity to 78 ± 0.24%.

Conclusion: Fraction DCM-I was able to antagonize angiotensin II-induced contraction to cause corpus cavernosum relaxation via inhibition of angiotensin II type 1 receptor and enhance bradykinin-induced relaxation through inhibition of angiotensin-converting enzyme.

Keywords: Angiotensin II; Angiotensin-converting enzyme; Bradykinin; Corpus cavernosum; Erectile dysfunction; Eurycoma longifolia Jack.

Figures

Fig. 1
Fig. 1
a Cumulative concentration-response curve of PE-induced contraction in corpora cavernosa of Sprague-Dawley rats. b Cumulative concentration-relaxation curve of ACh in PE-precontracted corpora cavernosa of Sprague-Dawley rats. Values are means ± SEM (n = 6).
Fig. 2
Fig. 2
Effects of partitioned fractions (a) and DCM subfractions (b) on PE-induced contractions. Values are means ± SEM (n = 6). ap < 0.05 compared with HX; bp < 0.05; bbp < 0.01 compared with BU; ccp < 0.01; cccp < 0.001 compared with FA; ++p < 0.01 compared with DCM-IV; ** p < 0.01 and *** p < 0.001 compared with DCM-V; ##p < 0.01 and ###p < 0.001 compared with DCM-VI.
Fig. 3
Fig. 3
Effects of DCM-I pretreatment on Ang I-induced (a) or Ang II-induced (b) contractions. Values are means ± SEM (n = 6). * p < 0.05, ** p < 0.01, and *** p < 0.001 compared with control (without DCM-I).
Fig. 4
Fig. 4
Effects of DCM-I pretreatment on Ang II-induced contractions (a) and BK-induced relaxations (b) in PE-precontracted corpora cavernosa. Values are means ± SEM (n = 6). * p < 0.05, ** p < 0.01, and *** p < 0.001 compared with control (without DCM-I).
Fig. 5
Fig. 5
Effects of DCM-I on activity of ACE. Values are means ± SEM (n = 3). * p < 0.05 and *** p < 0.001 compared with control (vehicle only).
Fig. 6
Fig. 6
Thin-layer chromatography plate of DCM-I sprayed with anisaldehyde-sulphuric acid reagent and heated at 105°C for 10 min. Spot observed (arrow) indicates the presence of terpenoids.

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