Essential oils derived from Mediterranean plants are widely used; nevertheless, the hydrodistillation waste produced with these oils are relatively unexplored and underutilized. With only partial data available in the literature, we analysed the chemical composition of by-products from hydrodistilled rosemary leaves. The solid residue of rosemary by-product (RSB) was extracted using 80% ethanol. The extract was tested for antioxidant activity and demonstrated a high effect. The overall phenolic content was 188 mg GAE/g, whereas the flavonoid content was 12 mg QE/g. caffeic acid (31.2%), naringenin (27.8%), apigenin (7.39%), hesperetin (5.06%), and coumaric acid (3.94%) were the most common components of RSB. the inhibitory concentration that inhibits 50% of the cancer cell population (IC50) for the cytotoxic action of RSB extract against HCT 116 (human colon) and PC3 (human prostate) cancer cell lines at varied concentrations (31.25-1000 µg/mL) was 31.4 µg/mL for HCT 116 and 33.4 µg/mL for PC3.We conclude that the solid residue of rosemary by-product leaves exhibits significant potential in the development of phyto-medicines with anticancer properties. Drugs derived from rosemary solid by-product (RSB) could serve as an alternative medicinal source due to their anticancer activity. Furthermore, this study suggests that the ethanol extract of this by-product possesses the greatest potential for anticancer activity against (HCT 116) Human colon and human Prostate (PC3) cancer cell lines.

Introduction