Comparative Study on the Content and Cytotoxicity of Pseudolaric Acid B in the Five Plant Parts of Pseudolarix kaempferi

Pseudolaric acids of Pseudolarix kaempferi (Pinaceae) have been known as diterpenoids with potent anti-fungal-, anti-microbial, and cytotoxic activities. In the present study, the five MeOH extracts were prepared from the five plant part (root bark, stem bark, leaf, the inner part of root, and cone) to find the relation between the concentration of pseudolaric acids and cytotoxicity. Pseudolaric acids B and C were isolated from the root bark of P. kaempferi to use them as standard compounds. The five extracts were tested on cytotoxicity against six cancer cell lines, A549 (lung), HCT116 (colon), MDA-MB-231 (breast), SNU638 (stomach), and SK-hep-1 (liver) by SRB assay, but against K562 (leukemia) by SRB- or MTT assay. HPLC quantification were performed on a Shisheido Capcell PAK C18 column ($5{\mu}m$, $4.6mm{\times}250mm$) using 254 nm wavelength. The cytotoxicity ($IC_{50}$, $0.36{\mu}g/ml$ on K562 cell lines) of the root bark extract was potent and the content (101.1 mg/g extract) of pseudolaric acid B was very high in the root bark. These results suggest that the MeOH extract obtained from the root bark could be developed as the anti-cancer agent with a high quantity of pseudolaric acid B.