Abstract
Jelly fig (Ficus awkeotsang Makino) is used to prepare drinks and desserts in Asia, owing to the gelling capability of its pectin via endogenous pectin methylesterase (PE) catalyzation. Meanwhile, substances with PE inhibitory activity (SPEI) in jelly fig achenes (JFA) residue were noticed to be able to impede the gelation. In this study, we characterized and isolated SPEI from JFA by a series of PE inhibition-guided isolations. Crude aqueous extract of JFA residue was mixed with acetone, and 90% acetone-soluble matter was further fractionated by Diaion HP-20 chromatography. The retained fraction with dominant PE inhibitory activity was collected from 100% methanol eluate. Results from high-performance liquid chromatography mass spectrometry (HPLC/MS) and hydrolysis-induced chromogenic transition revealed the SPEI as complex tannins. Total tannins content was determined in each isolated fraction, and was closely related to PE inhibitory activity. In addition, SPEI in this study could inhibit activities of digestive enzymes in vitro and may, therefore, be assumed to act as non-specific protein binding agent.
Highlights
Pectin methylesterase (PE, EC 3.1.1.11) is a ubiquitous enzyme in plants, bacteria, and fungi [1,2]
Crude extract powder of jelly fig achenes (JFA) was first dissolved in NaCl solution, boiled and centrifuged to eliminate pectin methylesterase (PE) and pectin residues
Inhibition assay, the inhibitory capacity was reduced to 15.3% as compared with while the control group was 97.7% (Figure 1B). These results indicate that JFA-substances with PE inhibitory activity (SPEI) possesses remarkable capacity to bind with PVPP to form a precipitated complex
Summary
Pectin methylesterase (PE, EC 3.1.1.11) is a ubiquitous enzyme in plants, bacteria, and fungi [1,2]. PE catalyses the removal of methylester from homogalacturonan domains in pectin to release methanol and protons in the apoplast, which affects the properties of the pectin matrix by influencing calcium–pectate interactions [3]. Pectin aggregates into calcium-linked gel structures, which increases wall porosity and reduces apoplastic pH, thought to activate local hydrolases including polygalacturonases and pectin lyases, thereby softening the cell wall and inducing the ripening of fruits [4]. SPEI were proposed to have several potential applications because of the strong interaction between inhibitory substances and PE. In wine production, SPEI may reduce the methanol content by attenuating the activity of endogenous PE in fruit tissue [6]. Several inhibitory substances have been identified from plants: side-branched uronic acid in potato tubers; Molecules 2019, 24, 1601; doi:10.3390/molecules24081601 www.mdpi.com/journal/molecules
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
