br Conclusions Sitosterol d glucoside and

Conclusions β-Sitosterol-d-glucoside (1) and five condensed tannin fractions (2, 3, 4, 5, and 6) were isolated from the leaves of Q. phillyraeoides. The α-glucosidase inhibitory and antioxidant activities of the isolated constituents were investigated. Four antioxidant assays were successfully conducted in order to evaluate the antioxidant activities of the plant extracts, with similar results being obtained. Of the isolated constituents, condensed tannin fractions (2–6) showed potent α-glucosidase inhibitory activities and antioxidant activities, while β-sitosterol-d-glucoside (1) showed moderate inhibitory activity against α-glucosidase. These constituents may be employed as lead constituents for potentially new antidiabetic medicine and antioxidants derived from plants. The results of the present study showed the potential of Q. phillyraeoides as a rich source of natural antioxidants and antidiabetic medicine.
Conflict of interest
Introduction Oxidative stress has been implicated in some neurodegenerative diseases such as Alzheimer\'s (AD) and Parkinson\'s diseases (PD). Free radical-induced neurodegeneration in ONX-0914 cells is usually caused by high levels of polyunsaturated fatty acid, low antioxidant capacity, high lipid content of myelin sheaths, high consumption of metabolic oxygen and lipid peroxidation in the cell membrane [1,2]. In addition, elevated levels of reactive oxygen species (ROS) can also induce oxidative damage in the nerve cells which can lead to neuronal injury and radical-induced cell death [3]. Furthermore, increase in monoamine oxidase (MAO) activity has been linked to the excessive production of free radicals, oxidative stress, neuronal injury and hydrolysis of neuro-active amines such as dopamine, serotonin etc. [4]. However, there are growing evidences that the inhibition of MAO activity could play a neuroprotective role in some neurodegenerative conditions [5]. Therefore the use of MAO inhibitors could be a good therapeutic strategy in the management/treatment of some neurodegenerative conditions such as AD and PD. Furthermore, several reports have revealed that decrease in the activities of cholinesterases (AChE and BChE), and stimulation of Na+/K+-ATPase activity relevant to the regulation of neurotransmitters and synaptic responses could help to improve cognitive and neuronal functions [6,7]. However, increase in AChE and BChE activities could lead to deficits in cholinergic neurotransmitters in AD patients, while decrease in Na+/K+-ATPase activity can induce glutamate neurotoxicity in PD [7–9]. Hence, inhibition of AChE and BChE activities and stimulation of Na+/K+-ATPase activity could be good therapeutic strategies in the management and/or treatment of AD and PD. Interestingly, previous report has established that cholinesterase inhibitors can also increase the activity of Na+/K+-ATPase [10]. Vladimir-Kneevic et al. [11] reported that consumption of medicinal plants can improve cognitive functions in neurodegenerative conditions. The use of dietary antioxidants and bioactive compounds from plants and plant extracts has also been established for the treatment/and or management of some neurodegenerative diseases. Heinsia crinita also known as bush apple (locally referred to as “atama” in Southern-Nigeria) is a shrub with dense crown, bisexual flowers and conspicuous leafy calyx lobes with edible fruits. The leaves are consumed either as vegetable in preparation of local cuisine or as component of alcoholic concoction for the treatment of some diseases such as bacterial infections, diabetes, hypertension and infertility [12,13]. However, to the best of our knowledge, the neuroprotective properties of H. crinita leaf extracts have not been reported. Therefore, this study was designed to investigate the neuroprotective potentials of aqueous and methanol extracts from H. crinita leaves via their effects on Fe2+-induced oxidative stress in rats’ brain and enzymes (MAO, AChE, BChE and Na+/K+-ATPase) linked to neurodegenerative diseases such as Alzheimer\'s diseases (AD) and Parkinson disease (PD).