Polyphenol Fingerprint, Biological Activities, and In Silico Studies of the Medicinal Plant Cistus parviflorus L. Extract.

ABSTRACT

Cistus parviflorus L. (Cistaceae) is a medicinal plant with several folkloric applications, including being used for urinary tract infections and as a food additive. In this study, the polyphenolic diversity and the antioxidant, antidiabetic, and antimicrobial activities of the C. parviflorus methanolic extract were evaluated. Spectrophotometric and HPLC-based analyses using standard polyphenolic compounds were conducted to measure the phenolics and flavonoids in the plant extract. The in vitro DPPH, ORAC, FRAP, and α-glucosidase assays were used to evaluate the plant's antioxidant and antidiabetic activities. Furthermore, disc diffusion and MIC-based microdilution tests were applied to evaluate the antimicrobial activity of the plant against broad-spectrum microorganisms. The analysis revealed the existence of high phenolic and flavonoid quantities that were measured at 302.59 ± 0.6 µg GAE and 134.3 ± 0.5 µg RE, respectively. The HPLC-based analysis revealed the existence of 18 phenolic acids and 8 flavonoids. The major phenolic acid was ellagic acid (169.03 ppm), while catechin was the major flavonoid (91.80 ppm). Remarkable antioxidant activity was measured using three different assays DPPH, ORAC, and FRAP. Furthermore, strong inhibition of α-glucosidase compared to acarbose was recorded for the plant extract (IC50 0.924 ± 0.6). The results showed that C. parviflorus's extract had a strong anti-Escherichia coli effect with MIC value of 0.98 µg\mL and IZD value of 32.2 ± 0.58 mm compared to 25.3 ± 0.18 mm for gentamycin, the positive control. Moreover, Aspergillus niger, Aspergillus fumigatus, Staphylococcus aureus, Streptococcus pyogenes, and Salmonella typhimurium all showed significant growth inhibition in response to the extract, a result that may be related to the use of the plant in traditional medicine to treat urinary tract infections. The docking study indicated the higher binding affinity of the major identified compounds, i.e., ellagic acid, rutin, naringin, catechin, and punicalagin, to the S. aureus gyrase-DNA complex, which might suggest the possible mechanisms of the plant as antimicrobial agents.