New hippuric acid derivatives of prospective MDR AcrAB-TolC efflux pump inhibition, isolated from the fossilized metabolic product of Procavia capensis, in vitro supported computational study.

ETHNOPHARMACOLOGICAL RELEVANCE: Hyraceum, the fossilized excreta of rock hyrax situated in Howtat Bani Tamim, Saudi Arabia, used by tribes' settlers to treat infection associated viruses and bacteria like respiratory, urinary and bladder tracts, as a remedy for epilepsy and hysteria, to treat colic and syphilis, and as a cure for back and abdominal. However, its definitive chemical constituents, biological activity, and pharmacodynamic mechanisms remain uncharacterized.

AIM OF THE STUDY: Comprehensive chemical characterization and biological evaluation of the Hyraceum extract in vitro supported by a through in silico computational study.

MATERIALS AND

METHODS

LC/MS was used to discover the chemical composition of Hyraceum. The -ve and +ve microbial strains like E. coli, P. aeruginosa, S. aureus, C. albicans, were used for antimicrobial and antibiofilm activities. DPPH, PMo, and FCR were used for the antioxidant activity, and the total phenolic content, respectively. Proteins correlated with bactericidal/bacteriostatic effects like IARS, DHPS, Ddl1, DHFR, etc., and AcrAB-TolC efflux pump were selected for the in-silico study. Compounds' descriptors were estimated using DFT, along with the ADMET prediction.

RESULTS

Two new hippuric acid derivatives were isolated using RP-HPLC and fully identified using 1D & 2D-NMR, along with, seven phenolic derivatives, eight methoxylated flavonoids, and three sterols were identified using UPLC-ESI-MS/MS. The Hyraceum fractions revealed highest values of 448.71 mg GAE/g (TPC), and 382.59 mg AAE/g (TAC), besides, varied inhibition rations and MICs were displayed against the bacterial and fungal strains with the destruction of the pre-formed biofilms. In-silico modelling demonstrated the multi-target antimicrobial activity of Hyraceum's constituents with prospective MDR AcrB efflux pump inhibition.

CONCLUSION

The Hyraceum composition of the hippuric acids, phenolic acids and/or their derivatives, methoxylated flavonoids and sterols could be accounted for its biological potentials via their ability to interact with the key amino acid residues at the receptors' active pockets for inhibition, along with, their MDR inhibition activity expressed in targeting AcrB efflux pump transporter.