This study was designed to determine the antioxidant properties and inhibitory effects of extract from Moringa oleifera leaves on angiotensin-I-converting enzyme (ACE) and arginase activities in vitro. The extract was prepared and phenolic (total phenols and flavonoid) contents, radical (nitric oxide (NO), hydroxyl (OH)) scavenging abilities, and Fe2+-chelating ability were assessed. Characterization of the phenolic constituents was done via high performance liquid chromatography-diode array detection (HPLC-DAD) analysis. Furthermore, the effects of the extract on Fe2+-induced MDA production in rats' penile tissue homogenate as well as its action on ACE and arginase activities were also determined. The extract scavenged NO∗, OH∗, chelated Fe2+, and inhibited MDA production in a dose-dependent pattern with IC50 values of 1.36, 0.52, and 0.38 mg/mL and 194.23 µg/mL, respectively. Gallic acid, chlorogenic acid, quercetin, and kaempferol were the most abundant phenolic compounds identified in the leaf extract. The extract also inhibited ACE and arginase activities in a dose-dependent pattern and their IC50 values were 303.03 and 159.59 µg/mL, respectively. The phenolic contents, inhibition of ACE, arginase, and Fe2+-induced MDA production, and radical (OH∗, NO∗) scavenging and Fe2+-chelating abilities could be some of the possible mechanisms by which M. oleifera leaves could be used in the treatment and/or management of erectile dysfunction.

This study was designed to evaluate the antioxidant and cholinesterase inhibitory activities of sulfated polysaccharides from Gracilaria gracilis (PGCL) and Ulva lactuca (PULV). PGCL and PULV were extracted and characterized with Scanning electron microscope-energy dispersive x-ray (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and Gas chromatography-mass spectroscopy (GC-MS). The radical (2,2-azinobis-3-ethylbenzothiazoline-6-sulfonate [ABTS] 2,2-diphenyl-1-picrylhydrazyl [DPPH], and hydroxyl [OH]) scavenging and metal chelating activities as well as their inhibitory effects on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities were also determined. SEM-EDX analysis revealed the presence of elements such as carbon, magnesium, calcium, phosphorus, and sulfur. The FTIR analysis also confirmed the presence of sulfate group in the polysaccharide samples. Some sugars such as glucose, galactose, arabinose, xylose, rhamnose, and allose were also identified using GC-MS. PGCL and PULV scavenged ABTS, DPPH and OH radicals in a dose-dependent manner. Moreover, PULV exhibited higher scavenging activity compared to PGCL. PGCL and PULV also reduced the activity of AChE (IC 50 = 132.73 and 106.93 µg/mL) and BChE (IC 50 = 124.93 and 93.45 µg/mL) respectively. PGCL and PULV exhibited antioxidant activity and possess cholinesterase inhibitory activity, hence these polysaccharides could be explored as ingredients for the development of functional foods with neuroprotective potentials.

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Background The development of cholinesterase (ChE) and monoamine oxidase (MAO) inhibitors for management of neurodegenerative diseases such as Alzheimer's disease (AD) has come with their undesirable side effects. Hence, research for potent but natural ChE and MAO inhibitors with little or no side effects is essential. This study investigated the potentials of alkaloid extracts from two Cola species as nutraceuticals for prevention and management of AD. Methods Alkaloid extracts were obtained from two Cola species (Cola nitida [KN] and Cola acuminata [KA]) by solvent extraction method. The extracts were characterized for their alkaloid contents using gas chromatography (GC). The effects of the extracts on ChE and MAO activities were investigated in vitro. Also, the extracts' ability to inhibit Fe2+-induced lipid peroxidation in rat brain homogenate, scavenge DPPH and OH radicals, as well as chelate Fe2+ were determined. Results GC characterization revealed the presence of augustamine and undulatine as the predominant alkaloids in the extracts. There was no significant (P > 0.05) difference in the inhibitory effects of the extracts on ChE activities. However, KA extract exhibited significantly higher (P < 0.05) MAO inhibitory effect than KN. Also, KA extract inhibited Fe2+- induced malondialdehyde (MDA) production in rat brain homogenate more significantly than KN, while there was no significant difference in DPPH and OH radicals scavenging, as well as Fe2+-chelating abilities of the extracts. Conclusions Our findings revealed that KN and KA alkaloid extracts exhibited significant effect in vitro on biological pathways that may contribute to neuroprotection for the management of neurodegenerative diseases.