Scientific evaluation of Tian Hua Fen (THF) - history, chemistry and application
Tian Hua Fen (THF) was first recorded as a medicine for reestablishing menstruation in "Quian Jin Yi Fang" (about 682 A.D.) and as an abortifacient in IvTai Ping Sheng Hui Fang" (992 A.D.). THF, prepared from the root tuber of Trichosanthes kirilowii Maxim (Cucurbitaceae), had been used locally in admixture with several other herbal ingredients with severe side reactions. Through series screening, an abortion—inducing protein, trichosanthin (T), of p1 9.4 has been isolated from the root tubers in pure crystals. It is composed of 234(3) amino acid residues: Ala28Arg13Asn17Asp9Gln9Glu10Gly12His1Ile15— Leu27Lys8Met4Phe9ProgSer24Thr13Trp1Tyr13val12; M.W.: found, 24,000; calculated, 25,682. T is obtained as a mixture of two homologous polypeptides differing only at their C— terminals. The C—terminal of one of them is —Met—OH, and that of the other, —Met—Ala—OH. Cyanogen bromide degradation of T gave 4 peptide fragments (CB1—4) and some free alanine. T, N—maleyltrichosanthin (MT) and CB1—4 were furthur subjected to enzymic degradations. The primary structure of T has been elucidated by sequencing T and all degradation peptide fragments from the N—terminals by usual Edman degradation methods and from the respective C—terminals by using carboxypeptidases A, B and Y. Trp was located in the T—200 position. X—ray crystallography revealed that T crystals from barbiturate buffer belong to monoclinic system and show 8 o(,—helices and 13 t3—strands constituting 4 — pleated sheets. T is parenterally employed as a safe abortifacient in dose of 1.2 mg for woman of mid pregnancy and in combination with other medicines for early pregnancy. It is also effective in treating hydatidiform moles, ectopic pregnancy as well as choriocarcinoma.