Phenolic Extracts from Clerodendrum volubile Leaves Inhibit Cholinergic and Monoaminergic Enzymes Relevant to the Management of Some Neurodegenerative Diseases.

This study investigated the inhibitory effects of phenolic-rich extracts from Clerodendrum volubile leaves on cholinergic [acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)] and monoaminergic [monoamine oxidase (MAO)] enzymes' activities and pro-oxidants [Fe2+ and quinolinic acid-(QA)] induced lipid peroxidation in rats brain homogenates in vitro. Free phenolic extracts (FPE) and bound phenolic extracts (BPE) were obtained via solvent extraction, and the total phenol and flavonoid contents were evaluated. The phenolic constituents of the extracts were also determined using high performance liquid chromatography coupled with diode array detector (HPLC-DAD). Our findings revealed that FPE had higher AChE (2.06 µg/mL), BChE (2.79 µg/mL), and MAO (2.81 µg/mL) inhibitory effects than BPE [AChE, 2.80 µg/mL; BChE, 3.40 µg/mL; MAO, 3.39 µg/mL]. Furthermore, FPE also had significantly (P < 0.05) higher inhibitory effects on Fe2+ and QA-induced lipid peroxidation compared to BPE. FPE (162.61 mg GAE/g) had higher total phenol content than BPE. However, BPE (18.65 mg QE/g) had significantly higher total flavonoid content than FPE (13.32 mg QE/g). Phenolic acids (such as gallic acid, catechin, chlorogenic, caffeic, ellagic, p-Coumaric acids) and flavonoids (catechins, rutin and quercetin) were present in both extracts. This study revealed that the enzymes' inhibitory activities and antioxidant potentials of phenolic-rich extracts from C. volubile could be part of the mechanism of actions behind its use for memory/cognitive function as obtained in folklore. However, FPE exhibited significantly higher enzymes, inhibitory and antioxidant potentials than BPE.

Interaction of some commercial teas with some carbohydrate metabolizing enzymes linked with type-2 diabetes: a dietary intervention in the prevention of type-2 diabetes.

This study is aimed at assessing the inhibitory effect of teas on key enzymes (α-amylase and α-glucosidase) linked with type-2 diabetes and their antioxidant properties. Four samples of three brands were used; infusions of green tea (GT), 2 brands of black tea (BT), and a formulated herbal preparation for diabetes (ADT) (white tea, Radix Puerariae, Radix ophiopogonis, hawthorn berry, Chinese yam, and fragrant Solomon seal rhizome) were prepared and subsequently analyzed for their total phenol, ascorbic acid contents, antioxidant properties (2,2-Azizobis (3-Ethylbenzo-Thiazoline~6-sulfonate) "ABTS" scavenging ability and ferric reducing antioxidant property), and inhibition of pancreatic-α-amylase and intestinal-α-glucosidase in vitro. The study revealed that GT had the highest total phenol content, ascorbic acid content, ABTS∗ scavenging ability, and ferric reducing ability. Furthermore, all the teas inhibited Fe(2+) and sodium nitroprusside induced lipid peroxidation in pancreas, with GT having the highest inhibitory effect. Conversely, there was no significant difference (P > 0.05) in the inhibitory effects of the teas on α-amylase and α-glucosidase. The antidiabetic property of the teas could be attributed to their inhibitory effect on carbohydrate hydrolyzing enzymes implicated in diabetes and their antioxidant activities.

Water Extractable Phytochemicals from Peppers (Capsicum spp.) Inhibit Acetylcholinesterase and Butyrylcholinesterase Activities and Prooxidants Induced Lipid Peroxidation in Rat Brain In Vitro.

Background. This study sought to investigate antioxidant capacity of aqueous extracts of two pepper varieties (Capsicum annuum var. accuminatum (SM) and Capsicum chinense (RO)) and their inhibitory effect on acetylcholinesterase and butyrylcholinesterase activities. Methods. The antioxidant capacity of the peppers was evaluated by the 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging ability and ferric reducing antioxidant property. The inhibition of prooxidant induced lipid peroxidation and cholinesterase activities in rat brain homogenates was also evaluated. Results. There was no significant difference (P > 0.05) in the total phenol contents of the unripe and ripe Capsicum spp. extracts. Ripe and unripe SM samples had significantly higher (P < 0.05) ABTS(*) scavenging ability than RO samples, while the ripe fruits had significantly higher (P < 0.05) ferric reducing properties in the varieties. Furthermore, the extracts inhibited Fe(2+) and quinolinic acid induced lipid peroxidation in rats brain homogenates in a dose-dependent manner. Ripe and unripe samples from SM had significantly higher AChE inhibitory abilities than RO samples, while there was no significant difference in the BuChE inhibitory abilities of the pepper samples. Conclusion. The antioxidant and anticholinesterase properties of Capsicum spp. may be a possible dietary means by which oxidative stress and symptomatic cognitive decline associated with neurodegenerative conditions could be alleviated.

Cyclophosphamide-induced oxidative stress in brain: protective effect of hot short pepper (Capsicum frutescens L. var. abbreviatum).

This study sought to characterize the distribution of phenols and antioxidant activities in hot short pepper (Capsicum frutescens var. abbreviatum) and their inhibition of cyclophosphamide-induced oxidative stress in rat's brain. The total phenol content and antioxidant activities of pepper flesh (pericarp) and seeds were determined in vitro and in vivo. The results of the study revealed that intraperitoneal administration of cyclophosphamide (75mg/kg of body weight) caused a significant increase (P<0.05) in the malondialdehyde (MDA) content of the brain; however, there was a significant decrease (P<0.05) in the brain MDA content, in those of rats fed diet containing pepper; the flesh showed a higher inhibitory effect. In addition, dietary inclusion of the pepper (seed and flesh) also caused a dose-dependent inhibition of serum glutamate oxaloacetate transaminase (SGOT), glutamate pyruvate transaminase (SGPT), alkaline phosphatase and total bilirubin; likewise, dietary inclusion of the flesh inhibited MDA production than the seeds. The higher inhibition of oxidative stress in brain and serum enzymes and metabolites by the flesh could be attributed to its significantly higher (P<0.05) total phenol content, reducing power and free-radical scavenging ability. Therefore, dietary hot short pepper (Capsicum frutescens L. var. abbreviatum) could prevent cyclophosphamide-induced oxidative stress in brain; although the flesh is a better protectant, the possible contributory role of the seeds cannot be neglected. However, this protective effect of the pepper could be attributed to their antioxidant properties.