Evaluation of the Antibacterial, Antioxidant, Anticancer, and Antidiabetic Activities of the Leaves and Inflorescences of Crassula capitella

Background/Objectives: Plants of the Crassulaceae family have been utilized in traditional medicine because of their medicinal properties. Crassula capitella, an ornamental succulent plant, has not yet received significant attention from physiochemists or pharmacologists. The objective of this study was to investigate the in vitro phytochemical properties and biological activity of methanolic extracts obtained from the leaves (CCLE) and inflorescences (CCIE) of C. capitella. Methods: Phytochemical screening included GC/MS analysis. The in vitro investigation of biological properties includes the assessment of antibacterial activity, utilizing disk diffusion assays and measuring MIC and MBC values for Gram-positive and Gram-negative bacteria. Antioxidant properties were determined through IC50 values in DPPH and ABTS assays. Cytotoxicity properties were evaluated using the MTT assay in MCF-7 and HepG2 cells, along with an analysis of apoptosis gene expression. Additionally, the antidiabetic effects were examined through α-amylase or α-glucosidase inhibition assays. Results: GC/MS analysis revealed distinct differences. CCLE contained more terpenoids such as betulinaldehyde (30.53%) followed by lupeol (19%) and betulin (4.07%), whereas CCIE was rich in fatty acids. The TPC and TFC of CCIE (88.17 mg GAE/g and 57 mg QE/g) were significantly greater than those of CCLE. Compared with CCLE, CCIE exhibited greater antibacterial properties (MIC values of 6.25 µg/mL toward S. aureus), greater antioxidant properties (IC50 values in the DPPH/ABTS assay), antitumor properties (IC50 values of approximately 90–96 µg/mL), and antidiabetic properties (IC50 values of 87–83 µg/mL in the α-amylase/α-glucosidase assay). Both bioactive extracts induced apoptosis in cancer cells by downregulating the expression of the tumorigenesis genes bcl-2 and bcl-xL. Conclusions: The findings provided the first evidence about the evaluated the potential antibacterial, antioxidant, anticancer, and antidiabetic activities of C. capitella, which is attributed to its robust chemical composition and position it as a compelling candidate for further in vivo and sub-clinical applications.