1989), and 3α-hydroxyoblongolide C, 8-acetylobolngolide P, and 1‴-hydroxyoblongolide X from the fruits of C. acuminata (Li et al. 2017).
A total of six minor indole alkaloids (camptacumotine, 19-O-methylangustoline, camptacumanine, naucleficine, angustoline, and dihydroisoquinamine) and glycosides (10-O-(1-β-D-glycosyl), camptothecin, syringaresinol-4,4′-O-bis-β-D-glucoside, hyperoside, and pumiloside) were isolated from the seeds of C. acuminata, and their identities were confirmed by analysis of spectral data (Lin et al. 1988a; Lin and Cordell 1990). Besides these phytochemicals, vincoside lactam and strictosidinic acid were also separated from the C. acuminata (Guo and Yuan 2016).
2.18.2 Culture Conditions
The synthesis of camptothecin and 10-hydroxycamptothecin was monitored with treatment of heavy metal ions, UV-B, methyl jasmonate (MeJA), abscisic acid, salicylic acid, and hydrogen peroxide in callus cultures of C. acuminata. During the course of treatments, it was found that UV-B light induced the synthesis of camptothecin by 10-fold higher than control. Similarly, the salicylic acid also stimulated the accumulation of 10-hydroxycamptothecin up to 25-fold higher than nontreated callus cultures (van Hengel et al. 1992; Pi et al. 2010). High-performance liquid chromatography (HPLC) analysis revealed that overexpression of ORCA3 gene in transgenic hairy roots enhanced the production of camptothecin (1.5-fold higher) than the control. The observed results show that ORCA3 can be considered as an effective regulatory gene for stimulating the metabolic flux in biosynthetic pathway of camptothecin (Ni et al. 2011).
Camptothecin, a potent antitumor alkaloid endemic in North China, was isolated from C. acuminata (Wall et al. 1966). It is highly active against Walker 256 rat carcinosarcoma and mouse leukemia, p388 and L1210. The clinical trials in patients with gastrointestinal cancer were at first very promising, but subsequent trials showed toxicity. Callus induction in C. acuminata was achieved on MS medium containing dichlorophenoxyacetic acid (2,4-D) and kinetin and developed suspension cultures in the presence of gibberellins, L-tryptophan, and conditioned medium, which yielded camptothecin at about 0.0025% on a dry weight basis (Sakato and Misawa 1974); similarly, when the cultures were cultured on MS medium containing NAA, production of camptothecin reached its maximum peak (Van Hengal et al. 1992).
The Chinese tree C. acuminata produces the anticancer and anti-retroviral drug camptothecin. Methods were developed for the clonal propagation of this important medicinal plant through shoot bud culture. Shoot buds were excised from 25- to 30-day-old seedlings, presoaked for 48 hours in three different liquid media containing BA, kinetin, or thidiazuron, and subsequently cultured on semi-solid medium of the same composition. Multiple shoots only developed from the BA presoaked explants with the maximum number of shoots initiated from buds presoaked in and grown on B5 medium containing BA. Individual shoots were removed from clusters and rooted on B5 supplemented with IBA (Jain and Nessler 1996).
Camptothecin is an anticancer and antiviral monoterpene-derived
