Changes in anticholinesterase, antioxidant activities and related bioactive compounds of carob pulp (Ceratonia siliqua L.) during ripening stages

Abstract

In the current study, in vitro neuroprotective effect of carob (Ceratonia siliqua L.) pulp (wild and cultivated varieties) at the unripe and ripe stage was investigated through testing against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), linked to Alzheimer’s disease (AD). As neurodegenerative disorders are strongly related to oxidative damage and metal accumulation, the antioxidant activity of carob extracts was determined by DPPH, ABTS, ferric reducing power (FRP), CUPRAC and ferrous iron chelating (FIC) assays at both ripening stages. Total phenolic (TPC), total flavonoids (TFC) and total condensed tannin contents (CTC) were also assessed. At the unripe stage, the samples of both varieties exhibited an interesting inhibitory effect against AChE and BChE with a strong antioxidant activity by scavenging free radicals and by acting as reducing agents. The result showed that the concentrations of TPC, TFC, and CTC were decreased significantly (P < 0.05) during ripening. The same observations were found for antioxidant activities. The results suggested that the extract of unripe carob may provide a substantial source of secondary metabolites, which act as natural antioxidants and as acetylcholinesterase inhibitors that may be beneficial in the treatment of AD.