Diterpenoid B derived from Plectranthus excisus inhibits the melanoma cell cycle in the B16 melanoma cell line.

Plectranthus excisus is widely distributed throughout northeast China. Its active ingredient, diterpenoids, exhibits significant antitumor effects. The present study examined the antitumor effects of diterpenoid B (DB), derived from Plectranthus excisus, and demonstrated that DB inhibited the proliferation of tumor cells by inhibiting the cell cycle. Reverse transcription­quantitative polymerase chain reaction and western blot analysis were used to determine mRNA and protein expression levels, respectively. The results revealed that exposure to DB increased the expression levels of the transformation associated, protein 53, and cyclin­dependent kinase inhibitor 1A, and decreased the expression of cyclin­dependent kinase 2. The results of the present study demonstrated that DB can inhibit cell cycle progression and, therefore, offers potential as a beneficial antitumor drug.