*2.5. Antibiofilm Assay*

Biofilms of *S. aureus* ATCC 25923, *S. aureus* ATCC 29213, MRSA ATCC 43300 and MRSA 562 were produced by using the method published elsewhere [35] in accordance with the CLSI guidelines [33]. Briefly, overnight grown reference cultures were suspended in tryptic soy broth (Himedia, Mumbai, India) supplemented with 2% glucose to attain turbidity equivalent to 0.5 McFarland standard (2 × 10<sup>8</sup> CFU/mL). A total of 100 μL of the cell suspension was transferred to the wells on the microtiter plate and was incubated at 37 ◦C for 24 h under static condition. Non-adherent cells were aspired out along with the medium. The wells were rinsed with 100 μL of phosphate-buffered-saline (PBS). Fresh medium containing desired concentrations of ADR1 metabolites (from 250 to 0.49 μg/mL) were added to the wells on the microtiter plate, which was then incubated for the next 24 h at 37 ◦C under static condition. Viability of the biofilms was quantified by INT-calorimetric assay as described above. The following equation was used to find % inhibition of biofilm [35].

$$\text{Biodium inhibition (\%)}=\text{[(control OD }\_{490\,\text{nm}}-\text{test OD }\_{490\,\text{nm}})\text{(control OD }\_{490\,\text{nm}}] \times 100\tag{2}$$
