A factor controlling β-thujaplicin production in suspension culture of Cupressus lusitanica

Suspension cell culture of Cupressus lusitanaca produce β-thujaplicin, a heart wood tropolone. The product inhibition in the β-thujaplicin biosynthesis was investigated in the present paper. Initial cell density at the beginning in the culture did not affect the β-thujaplicin accumulation level, and the initial addition of β-thujaplicin to the culture suppressed its de novo production. When β-thujaplicin accumulation was reached at a certain level (ca. 40mg/l) in the C. Lusitanica culture medium, the culture seemed to cease β-thujaplicin production. However, the culture regained β-thujaplicin productivity if the β-thujaplicin-containing medium was exchanged for new one. The formation of β-thujaplicin methyl ether was also observed. These results suggest that β-thujaplicin synthesis was regulated by the product feed back mechanism in this cell line and the excess accumulation β-thujaplicin would be relieved by the conversion to its methyl ether.