Abstract:
Plants with aphrodisiac potentials have been reported useful in traditional medicine for the
management of erectile dysfunction. Hence, this study sought to investigate the effect of axlewood,
swizzle stick, longjack, hallier F, mahogany and african greenheart extracts on some enzymes
[arginase, phosphodiesterase-5 (PDE-5), angiotensin-1-converting enzyme (ACE) and
acetycholinesterase (AChE)] relevant to erectile dysfunction in vitro. The antioxidant properties
of the extracts were evaluated through radicals (ABTS*, DPPH* and OH*) scavenging assays,
metals (Fe2+ and Cu2+) chelating assays and inhibition of Fe2+ and sodium nitroprusside (SNP)
induced lipid peroxidation. Also, phenolic contents were characterized using HPLC-DAD. The
results revealed that the extracts inhibited arginase, PDE-5, ACE and AChE activity in a
concentration-dependent manner. From the results, axlewood had the highest arginase (IC50 =
38.01 μg/ml) and PDE-5 (IC50 = 174.19 μg/ml) inhibitory effect, longjack had the highest AChE
inhibition (IC50 = 212.30 μg/ml), while swizzle stick had the highest ACE inhibitory effect (IC50
= 108.64 μg/ml). Also, the extracts exhibited antioxidant properties through radicals scavenging
and metal chelating abilities. However, axlewood had the highest DPPH* scavenging ability (IC50
= 0.49 mg/ml), Fe2+ (IC50 = 0.15 mg/ml) and Cu2+ (IC50 = 0.10 mg/ml) chelating abilities, whereas
longjack had the highest OH* scavenging ability (IC50 = 0.09 mg/ml). HPLC-DAD
characterization revealed the presence of gallic acid, chlorogenic acid, caffeic acid, rutin and
quercetin. Hence, the inhibition of enzyme activities relevant to erectile dysfunction as well as
antioxidant properties of the extracts partly suggest possible mechanisms underlying their use in
the management of erectile dysfunction as reported in traditional medicine. However, axlewood
extract exhibited highest potential over other extracts.
