Interaction of 7,8-dihydroxycoumarin with a biopolymer bromelain: Synthesis, spectroscopic and molecular docking insights

Dihydroxycoumarins which are present in nature as natural products in medicinal plants used for herbal treatment, have numerous pharmacological and therapeutic potentials. They can be developed as promising components of treatment in various medicinal fields. Regardless of several advantages, they have a few disadvantages like low molecular weight and low solubility which lowers the appropriate bioavailability. The strategy is to identify effective intake with a carrier for oral drug delivery. In this paper, we synthesized daphnetin (7,8-dihydroxycoumarin) which has various medicinal properties in a pot-economical multicomponent domino fashion, and explored its biophysical interaction with cysteine protease enzyme bromelain for the very first time using steady-state fluorescence and temperature variation experimentally at pH 7.4 since it has a proven record of enhancing the efficacy of drugs. The binding constant (or stability constant) of the bromelain-daphnetin interaction is determined from the double-logarithmic plot at three different temperatures, 288K, 298K, and 308K. The change of enthalpy and entropy revealed the major forces of interaction. Thus, bromelain can be used as a drug carrier for daphnetin.