Shahrekord University of Medical Sciences Journal of Shahrekord University of Medical Sciences 2717-0071 26 4 2024 12 30 Phytochemical contents, in vitro and in vivo antioxidant and anticancer activities of avocado (Persea americana Mill.) seed extract against MCF-7 and HMVII cancer cells 172- 184 10.34172/jsums.960 EN Cletus Anes Ukwubile https://orcid.org/0000-0001-7183-4510 Aishat Omolabake Makinde https://orcid.org/0009-0007-5975-2214 Journal Article 10.34172/jsums.960 2024 03 07 2024 04 13 Background and aims: Avocados are unique in Nigeria for their taste and medicinal uses. This study was performed to determine the phytochemicals and evaluate the antioxidant and cytotoxic effects of avocado seed extracts (ASEs). Methods: The phytochemicals were analyzed using the gas chromatography-mass spectrometry (GC-MS) apparatus. The total phenolic and flavonoid contents and in vitro antioxidant activity were evaluated using standard methods. In contrast, in vivo, antioxidants were used in a group of thirty healthy Wistar rats randomly grouped into five groups of six, with cytotoxicity activity by benchtop and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assays and apoptosis by assessing caspase-3-like activity. Results: The GC-MS revealed polyphenols and fatty acids. Phenolic and flavonoid contents were 1178.67 mg gallic acid equivalent per gram (GAE/g) and 86.24 mg rutin equivalent per gram (RE/g), respectively. High radical scavenging toward 2,2-diphenyl-1-picrylhydrazyl (DPPH), ABTS, and ferric reducing antioxidant power (FRAP) reducing power with IC50 values of 25.25±1.01 µg/mL, 38.22±2.01 µg/mL, and 43.99 mM Fe (II) equivalent, respectively, in vitro antioxidation as well as dose-dependent in vivo antioxidant activities with reduced malondialdehyde (MDA), total superoxide dismutase (TSOD), and catalase (CAT) and increased glutathione peroxidase (GSH-Px) contents in vital organs were obtained. Cytotoxic effects on MCF-7 and HMVII cells were detected, with IC50 values of 16.51±0.02 µg/mL and 31.71±2.03 µg/mL, respectively, which was statistically significant (P=0.001) when compared to doxorubicin standard drug and a higher selective index on breast cancer (BC). Conclusion: The findings revealed that avocado seed possessed antioxidant and anticancer activities on human MCF-7 and HMVII cancer cell lines.