ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Chemical composition, in vitro antioxidant and antimicrobial activities of carob pulp (Ceratonia siliqua L.) from Tunisia

Imene Khelouf, Iness Jabri Karoui, and Manef Abderrabba

Laboratory of Materials Molecules and Applications, Praparatory Institute for Scientific and Technical Studies, Carthage University, La Marsa, Tunisia

E-mail: khelouf.imane@gmail.com

Received: 24 February 2023  Accepted: 10 June 2023

Abstract:

The main aim of this study was to establish the chemical composition, and phenolic compounds, as well as to investigate in vitro antioxidant and antimicrobial activities of carob grown in Tunisia. Carob pulp meal contained high levels of carbohydrates (44.18%) primarily consisting of 37.05% sucrose, 7.45% fructose, and 2.67% glucose along with appreciable amounts of protein (6.48%), fiber (3.11%), and low-fat content (1.32%). Carob pulp is considered a rich source of Ca (2646.4 mg/kg DW), Mg (504.3 mg/kg), and also incorporates minor amounts of Fe (10.1 mg/kg), and Cu (< 2.5 mg/kg). Carob pulp ethanolic extract contained a mean value of 30.84 mg GAE/g DE of total polyphenols, 1.47 mg QE/g DE of flavonoids, and 1.12 mg CE/g DE of condensed tannins. Moreover, it had an important antioxidant activity: ABTS (70.3ug/mL), DPPH (114.4ug/mL), FRAP (217.23 µmol FeSO₄/g DE). The analysis of HPLC of ethanolic extract of carob pulp identified six organic compounds. Isorhamnetin (5.67 mg/g DE) and quercetin (3.21 mg/g DE) recorded the highest values. The antimicrobial activity was revealed on five microorganisms. Ethanolic extract showed moderate antibacterial and antifungal activities with diameters inhibition zones ranging from 6 to 25 mm.

Graphic abstract

Keywords: Ceratonia siliqua L.; Chemical composition; Antioxidant activity; HPLC; Antimicrobial activities

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-02926-w

Chemical Papers 77 (10) 6125–6134 (2023)