This is the 4295th most frequent Russian word.
антиоксиданты
Substances that inhibit oxidation and protect cells from damage caused by free radicals.
In this sentence, "антиоксиданты" is used as the subject of the sentence, referring to substances that have protective effects on cells.
Антиоксиданты помогают защитить клетки от повреждений.
Antioxidants help protect cells from damage.
Here, "антиоксидантами" is used in the instrumental case, indicating the means by which the fruits are beneficial.
Многие фрукты богаты антиоксидантами, что делает их полезными для здоровья.
Many fruits are rich in antioxidants, which makes them beneficial for health.
In this example, "антиоксидантов" appears in the genitive case to denote the topic of study.