Capsicum annuumvar.grossum(Bell Pepper) Inhibitsβ-Secretase Activity andβ-Amyloid_1–40Aggregation

Abstract

The deposition of amyloid protein as senile plaques is the major signature of Alzheimer's disease (AD). It is produced by the sequential cleavage of the amyloid precursor protein by secretases. Moreover, peppers are noted for their antiaging and cognitive enhancing properties. Thus, in this study, the effects of polyphenol-rich extracts from bell pepper on amyloid production and aggregation in vitro were investigated. Bell pepper (ripe and unripe) was extracted with methanol-1 N HCl (1:1 v/v). Thereafter, the inhibitory potentials of the extracts on β-secretase and β-amyloid aggregation were determined. Phenolic composition of the pepper fruits was further determined by HPLC-DAD (high performance liquid chromatography-diode array detector). There was a dose-dependent inhibition of β-secretase by the pepper fruits with the ripe fruits (2.17 ± 0.17 μg/L) showing a significantly (P < .05) higher inhibitory effect than the unripe (3.44 ± 0.11 μg/L). Furthermore, Thioflavin-T and transmission electron microscopy analyses revealed that phenolic extracts from pepper fruits (1 and 10 μg/L) could counteract the initial aggregation of Aβ, as well as prevent further aggregation preformed fibrils. These inhibitory activities could be attributed to the predominant presence of phenolic constituents in the pepper fruits. It is possible to conclude that bell pepper could be a possible dietary intervention into the management of AD.

Color for Life: Biosynthesis and Distribution of Phenolic Compounds in Pepper (Capsicum annuum)

“…Mudric et al [113] studied different cultivars and varieties of Capsicum ("Lemeška" sweet, "Lemeška" hot, "Lemeška" semi-hot and "Lakošnicka") harvested in different years. Ogunruku et al [117] analyzed the variety "Grossum" in ripe and unripe maturity stages. Materska et al [121] studied two hot pepper cultivars, "Cyklon"and "Bronowicka Ostra", and two semi hot cultivars, "Tajfun" and "Tornado", at two different maturity states.…”

“…Phenolic acids from both subfamilies are reported in C. annuum L. fruits, leaves, stems and placenta. The major hydroxybenzoic acids present in Capsicum fruits are gallic acid (maximum reported 1013.0 mg/kg fw) and vanillic acid (13.29 mg/kg fw) [111][112][113]117]. Vanillic acid is present in Capsicum stems and placenta, and p-hydroxybenzoic acid was also detected in pepper's placenta [112].…”

“…Flavonols are perhaps one of the major flavonoid subfamilies present in peppers. They are structurally similar to flavones, with an additional hydroxyl group present on carbon 3 of ring C. Quercetin and its derivatives are the major flavonols present in Capsicum, with quercetin (783.83 mg/kg fw) [107,109,113,117,118,123] and quercitrin (1501.8 mg/kg fw) [108,117,118,120] occurring in high contents. Other flavonols like kaempferol and its glycosides were also reported with 1.3-160 mg/kg fw.…”

Diversity and Potency ofCapsicumspp. Grown in Indonesia

“…Another study reported that Capsicum annuum var. grossum could be an alternative intervention for Alzheimer's disease (AD) by inhibiting β-secretase activity and β-Amyloid 1-40 aggregation [38]. It is stated that phenolic extracts from the fruits could counteract the initial aggregation of Aβ 1-40 , as well as prevent further aggregation of preformed fibrils.…”

Aqueous–ethanol extracts of some South African seaweeds inhibit beta‐amyloid aggregation, cholinesterases, and beta‐secretase activities in vitro

“…ThT solution and phosphate-buffered saline, pH 6.6 was used as a blank. This was done at time t = 0, 24, 48, 72, and 96 hr) (Ogunruku, Oboh, Passamonti, Tramer, & Boligon, 2017).…”