Ethnopharmacological Survey, Mineral and Chemical Content, In Vitro Antioxidant, and Antibacterial Activities of Aqueous and Organic Extracts of Chamaerops humilis L. var. argentea Andre Leaves

Abstract

Introduction. The present study is carried out for the first time on Chamaerops humilis L. var. argentea Andre from the region of Taza using an ethnopharmacological survey, an experimental study of the mineralogical and chemical compositions, and evaluations of the antioxidant and antibacterial activities. Methods. After conducting the ethnopharmacological survey, a mineralogical and phytochemical study involving the preparation of aqueous and organic extracts was done. Essential oils were also extracted by hydrodistillation. Subsequently, qualitative and quantitative chemical analyses were performed. In vitro evaluation of antioxidant activities was performed by five tests (H2O2, DPPH, ABTS, FRAP, and RP) and antibacterial activities by the disc method and determination of MIC and MBC. A principal component analysis (PCA) was performed to visualize the different correlations. Results. The different parts of the plant are used for the treatment of digestive disorders, cardiovascular diseases, and diabetes. In addition, the leaves are rich in mineral compounds, catechic tannins, flavonoids, and sterols. However, they have some traces of essential oils. The quantitative analysis revealed that the ethanolic macerated had a higher content of total polyphenols ( $100.27\pm 1.95\text{mg}$ EAG/g E) and catechic tannins ( $52.11\pm 1.02\text{mg}$ EC/g E). This extract had a strong antioxidant capacity (H2O2 ( $37.34\pm 0.55\%$ ), DPPH ( $\text{I}{\text{C}}_{50}=31.18\pm 0.66\mu \text{g}/\text{ml}$ ), ABTS ( $108.28\pm 1.29\text{mg}$ E AA/g E), FRAP ( $148.85\pm 0.43\text{mg}$ E T/g E), and RP ( $10.86\pm 0.01\text{mg}$ E AA/g E). The same extract had a bactericidal effect against Staphylococcus aureus. Principal component analysis (PCA) showed that antioxidant activity was highly correlated with the chemical composition of C. humilis leaves; a high correlation was recorded between the total polyphenol content and ABTS ( $r=0.9779$ ), FRAP ( $r=0.9644$ ), DPPH ( $r=0.9418$ ), and PR ( $r=0.9271$ ) tests. In addition, cathectic tannins were highly correlated with the tests of DPPH ( $r=0.9753$ ) and ABTS ( $r=0.8843$ ). Flavonoids were similarly correlated with DPPH ( $r=0.8897$ ) and ABTS ( $r=0.7599$ ) tests. Conclusion. These results could justify the traditional use of the leaves of Chamaerops humilis in the region of Taza for the treatment of some diseases.