Investigation of in vitro therapeutic potential of Phlomoides moluccelloides (Bunge) Salmaki plant extracts

Medicinal plants form the basis of many drugs used in modern medicine today. Therefore, it is important to examine the biological activities of endemic plant species that have not been studied before and bring them to the literature. This thesis focused to define the antibacterial, anti-quorum sensing, and antiproliferative features of methanol (MeOH) and infusion extracts of the aerial and root fragments of Phlomoides moluccelloides (Bunge) Salmaki. The antiproliferative activity was investigated on HeLa, MCF-7, and MDA-MB-231 cancer cell lines using the MTT test. The minimal inhibitory concentration (MIC) ratios of the extracts were analysed against reference bacterial strains using the broth microdilution assay. Anti-quorum sensing effects of the extracts were examined on inhibition of violacein and pyocyanin pigments production, suppression of biofilm formation, and inhibition of swarming motility in Pseudomonas aeruginosa PAO1 and Chromobacterium violaceum ATCC 12472 bioreporter strains. All extracts had dose-dependent antiproliferative activity against the MCF-7 cells, whereas only the MeOH extract of the aerial part had dose- and time-dependent antiproliferative activity against HeLa and MDA-MB-231 cancer cells. In addition, the infusion extract of the aerial part had dose- and time-dependent antiproliferative activity against the HeLa cell line. The most potent result was determined for the MeOH extract of aerial part on the MCF-7 cells at the 48th hour of the application (IC50 = 875.7 µg/mL). The minimal inhibitory concentration (MIC) ratios of all extracts against the tested bacteria were > 2000 µg/mL. Every extract partially suppressed the swarming motility of P. aeruginosa. Besides, MeOH extract of the aerial part restricted pyocyanin production by 81.7% without affecting bacterial growth. As far as biofilm formation and production of violacein pigments were concerned, the extracts exhibited no significant inhibitory effects. The findings displayed that P. moluccelloides have an antiproliferative effect on cancer cells and may be a good anti-quorum sensing agent. Further analyzes are recommended to solve the mechanisms that cause these biological activities.