Plants Used In Cancer Treatment Part - III. Camptotheca acuminata – the happy tree.
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Transcript of Plants Used In Cancer Treatment Part - III. Camptotheca acuminata – the happy tree.
Camptotheca acuminata – the happy tree
Tree in the Nyssaceae (Liriodendron family)
Distribution Use in traditional medicine Late 1950s - NCI screening 1966 - a quinoline alkaloid camptothecin
(CPT) was isolated from bark (and wood)
Early clinical trials of CPT
Solubility problems with CPT 1985 interest renewed Late 1980s semi-synthetic derivatives Current status
– Two semi-synthetics approved: Topotecan (Hycamptin) and Irinotecan (Camptosar)
Other CPTs
Other CPTs undergoing clinical trials for various forms of cancer– 9-nitrocamptothecin– BAY-38-3441– Exatecan– 9-aminocamptothecin
CPTs also being investigated as anti-viral drugs, esp anti-HIV
Source of CPTs
Population decline of Camptotheca acuminata trees in China
Plantations in US Found in leaves Laboratory synthesis New source of CPTs - Camptotheca
lowreyana
Lapacho
Tabebuia impetiginosa - tree in the family Bignoniaceae (catalpa family)
Distribution Traditional uses in South America Available as a dietary supplement Lapachol isolated in 1884 Beta-lapachone identified later
Lapachol and Beta-lapachone
Both are simple phenolic compounds
Lapachol is a napthaquinone
Beta-lapachone is a quinone
Both have anti-cancer properties but are both highly toxic
Evaluation
Early studies in South America NCI - effective but side effects too great Current investigations – Beta laphone
– Mode of action Derivative: 3-allyl-beta-lapachone Interest in anti-viral activity of beta-
lapachone Use of lapacho teas as dietary supplements
Aspergillus fumigatus
Morphology and characteristics of Aspergillus
Environmental sources Thermophilic fungus Human pathogen
Fumagillin
Antibiotic from Aspergillus fumigatus Discovered in 1953 – not widely used for
human infections – used for animals Recent interest as anti-malarial and other
protozoans Accidental discovery led to observation of
death of endothelial cell cultures
Fumagillin derivative
Animal studies showed fumagillin inhibited vascularization of tumors in mice but quite toxic
Semisynthetic derivatives of fumagillin developed
TNP-470 now in Phase I, II, and III clinical trials for various types of cancer
Inhibits vascularization of tumors by arresting endothelial cell cycle in late G1 stage
Iscador
Extract from Viscum album Widely used as a complementary therapy to
conventional chemotherapy drugs– Lectins appear to be active components– Stimulates parts of the immune system that can
slow the growth of cancer cells– Improves quality of life for cancer patients