In Vitro Biological Profiles and Chemical Contents of Ethanolic Nest Entrance Extracts of Thai Stingless Bees Tetrigona apicalis

Abstract

Tetrigona apicalis is a species of stingless bees found in Lower Northern Thailand. They normally construct their nest entrances as an external structure for protecting themselves from enemies. Their biological properties have not well characterized yet. The objectives of this study were to evaluate the antibacterial, antifungal and antiproliferative activities of their nest entrances. Samples were collected from four provinces and then extracted using 70% ethanol, finally called as ethanolic Nest Entrances Extracts (eNEEs). Broth microdilution method was applied to determine their antimicrobial effects. The cytotoxicity was examined to evaluate their anti-proliferative effects. The total phenolic and flavonoid concentrations were determined using colorimetric methods. Overall, the MICs were between 6.25 and >12.5 mg/mL against the bacteria tested whereas were between 1.56 and >12.5 mg/mL for the yeasts tested. The IC50 of HeLa cells was lower than that of LEP cells. TPC (19.3-24.1 mg PGE/g dried eNEEs) and TFC (2.4-4.8 mg QE/g dried eNEEs) contained in the eNEEs with the major substances of hydroquinin and quercetin. In conclusion, the Thai ethanolic nest entrance extracts possess the antibacterial, antifungal and anti-proliferative activities.

Hydroquinine Inhibits the Growth of Multidrug-Resistant Pseudomonas aeruginosa via the Suppression of the Arginine Deiminase Pathway Genes

“…Hydroquinine is an organic compound that has been shown to possess antimicrobial properties [ 10 ]. Kraikongjit et al (2018) [ 11 ] and Jongjitvimol et al (2020) [ 12 ] have previously demonstrated that ethanolic nest entrances extracts from Tetrigona apicalis exhibit antibacterial, antifungal, and anti-proliferative activities [ 11 , 12 ]. Interestingly, one of the key chemical compounds found from the extracts was the polyphenol, hydroquinine.…”

High-Throughput Transcriptomic Profiling Reveals the Inhibitory Effect of Hydroquinine on Virulence Factors in Pseudomonas aeruginosa

“…Hydroquinine, an alkaloid organic compound found in particular natural products [ 28 , 29 , 30 ], was recently reported to inhibit and kill drug-sensitive (DS) and MDR strains of P. aeruginosa [ 31 ]. In addition, other alkaloid compounds have been reported to possess antimicrobial properties and anti-virulence factors in both Gram-positive and Gram-negative bacteria, such as inhibition of QS signaling and pigment production in P. aeruginosa [ 26 ], inhibiting biofilm formation in E. coli and P. aeruginosa [ 24 ] and inhibiting virulence gene expression in S. aureus [ 32 ].…”

Hydroquinine Enhances the Efficacy of Contact Lens Solutions for Inhibiting Pseudomonas aeruginosa Adhesion and Biofilm Formation

“…Many natural compounds have been used for ocular therapies because of their antiinfective and anti-inflammatory properties [24]. Interestingly, hydroquinine is a natural substance that has been shown to possess antimicrobial properties [25,26]. Kraikongjit et al (2018) [25] and Jongjitvimol et al (2020) [26] have previously demonstrated that hydroquinine is one of the key substances in the ethanolic nest entrance extracts from Tetrigona apicalis that exhibit antibacterial, antifungal, and anti-proliferative activities [25,26].…”

“…Interestingly, hydroquinine is a natural substance that has been shown to possess antimicrobial properties [25,26]. Kraikongjit et al (2018) [25] and Jongjitvimol et al (2020) [26] have previously demonstrated that hydroquinine is one of the key substances in the ethanolic nest entrance extracts from Tetrigona apicalis that exhibit antibacterial, antifungal, and anti-proliferative activities [25,26]. Moreover, hydroquinine has anti-malarial and anti-melanin activities, which may be used for reducing light-brown skin patches and skin discoloration associated with pregnancy [27].…”