Apoptotic Effects of Agapanthus africanus Extracts and Identification of Volatile Compounds from the n-Butanol Fraction

Agapanthus africanus (L.) Hoffmanns. is a medicinal plant traditionally used in South Africa for its promise as a source of bioactive compounds with anticancer properties. This study aimed to investigate the apoptotic effects of A. africanus fractions on cancer cell lines and to identify the bioactive phytochemical constituents using gas chromatography-mass spectrometry analysis. To test for cytotoxicity, MCF-7, A549, and HeLa cancer cells were treated with crude extract, n-hexane, n-butanol, dichloromethane, and aqueous fractions of A. africanus extracts at different concentrations (0.00–1000 µg/mL). Total apoptosis was quantified using Annexin V/PI staining. The 4′,6-diamidino-2-phenylindole was used to detect nuclear morphological changes and the Caspase-GLO 3/7 assay was employed to check the caspase activation in the cancer cells. Expression of apoptosis-related (caspase-3, bax, bcl-2) genes was evaluated using real time-polymerase chain reaction. The crude extract of A. africanus exhibited dose-dependent cytotoxicity against MCF-7, A549, and HeLa cells, with IC₅₀ values of 130 µg/mL, 380 µg/mL, and <125 µg/mL, respectively. Among the tested fractions, the n-butanol fraction showed cytotoxicity towards MCF-7 cells with an IC₅₀ value of <870 µg/mL. In contrast, n-hexane, dichloromethane and the aqueous fractions exhibited higher IC₅₀ values against cancer cells. Flow cytometry analysis, which was applied to quantify total apoptosis, revealed that the crude extract of A. africanus induced apoptosis by (~60%) compared to the n-butanol fraction, which exhibited a moderate apoptotic effect (~27%). DAPI nuclear staining showed nuclear shrinkage and chromatin condensation in the MCF-7 cell line, whereas in Caspase-GLO 3/7, the crude extract and n-butanol fraction resulted in significant luminescence, indicating activation of caspase-3/7. Caspase-3/7 analysis showed A. africanus treatments produced varying levels of apoptotic activation. The crude extract increased caspase activity by 2.9-fold, while the n-butanol fraction induced a 1.7-fold rise compared with untreated cells. GC-MS chromatograms detected and identified 16 compounds in the fractionated n-butanol and 23 compounds from the crude extract of A. africanus. The major compounds identified from the n-butanol fraction included n-hexadecanoic acid; α-tocopherol and 9,12,15-octadecatrienoic acid, while the GC–MS profile of the crude extract was dominated by 6,10,14-trimethylpentadecan-2-one; 1,3,5-Triphenylcyclohexane and phytol. The study indicates the pro-apoptotic potential of A. africanus, particularly in its crude form, supporting its ethnopharmacological use and suggesting its relevance as a candidate for anticancer drug discovery.