In Silico Pharmacokinetics Properties and In Vitro Bioactivities of Pregnane Derivatives and Other Compounds From Stems of Caralluma speciosa

Objectives Caralluma speciosa (N.E. Br.) N.E. Br. (Asclepiadaceae) and other succulent plants of the genus Caralluma have mainly been known for their appetite suppressing and weight loss properties, due to the presence of pregnane compounds. This study aimed to investigate chemical constituents and evaluate antimicrobial and antioxidant activities of stems of C speciosa. Methods The chloroform and methanol stems extracts were subjected to silica gel chromatographic separation. The structures of isolated compounds were established by FT-IR, 1D-NMR, and GC-MS instruments, and in comparison with reported data. The antimicrobial and antioxidant activities were performed using agar disc diffusion and DPPH assaying methods. Results The phytochemical investigation afforded 5 compounds, 3 pregnane derivatives (3-5), and 2 other compounds, heptacos-1-ene (1) and di-(2-ethylhexyl) phthalate (2). The chloroform: methanol (1:1) extract showed a good antifungal activity against Candida albicans up to 25 mg/mL dose (9.00 ± 1.00 mm to 17.17 ± 1.04 mm), equivalent to ketoconazole standard (17.67 ± 2.52 mm at 0.01 mg/disc). Compounds 3 and 5 were found violated 3 of the Lipinski's rule of 5. Compounds 2 and 4 exhibited a carcinogenicity property; while compounds 3, 4, and 5 were found as immunotoxic isolates. Conclusion All the extracts and isolated compounds 1-5 showed a negligible antibacterial and antioxidant activities compared to the antibiotic chloramphenicol (7.3 ± 0.4 to 21.15 ± 0.5 mm) and antioxidant ascorbic acid (IC50 value of 5.62 µg/mL). Hence, further biological activities study (including the anticancer, anti-inflammatory, and antifungal activities) would be needed on all the extracts and isolated compounds to look for better efficacy and predict the structure–activity relationship of the compounds.