Chinese Cucumber

Scientific Name(s): Trichosanthes kirilowii Maxim. Family: Cucurbitaceae

Common Name(s): Chinese cucumber , Chinese snake gourd , gua-lou , tian-hua-fen , compound Q

Uses

Chinese cucumber has been used to induce abortion. It possesses antitumor activity and has been used to treat invasive moles. Chinese cucumber is being studied as a treatment for the management of AIDS infections.

Dosing

There is no recent published clinical evidence to guide dosage of Chinese cucumber. It is most commonly administered as part of a polyherbal preparation in TCM.

Contraindications

Contraindications have not yet been identified.

Pregnancy/Lactation

Documented adverse effects. Avoid use. 1

Interactions

None well documented.

Adverse Reactions

Side effects include hormone changes, allergic reaction, fluid in the lungs or brain, bleeding in the brain, heart damage, seizures, and fever.

Toxicology

Extracts of the Chinese cucumber are extremely toxic (death has occurred), particularly with parenteral use.

Botany

The chinese cucumber is one of more than 40 recognized species of Trichosanthes . It is a member of the gourd family, and the root, fruit, seeds, stems and peel are used medicinally. While T. kirilowii is the plant most often referred to in Chinese Materia Medica, a number of related species are often used as adulterants.

History

T. kirilowii has a long history in traditional Chinese medicine where it is used to reduce fevers, swelling and coughing. A starch extracted from the root is used for abscesses, amenorrhea, jaundice and polyuria. Modern Chinese medicinal uses include the management of diabetes and use as an abortifacient. 2 The plant has been used for centuries in the treatment of tumors.

Chemistry

The most studied component of T. kirilowii is the protein trichosanthin. 3 , 4 Two trichosanthins have been identified: Alpha from T. kirilowii and beta from T. cucumeroides . A highly purified form of trichosanthin has been investigated under the name GLQ-223. A second protein, trichokirin, was isolated and found to possess ribosome-inactivating activity. 5 A later study reports that a peptide trypsin inhibitor isolated from T. kirilowii roots may be the smallest naturally occurring protein inhibitor. 6

An abortifacient protein, karasurin, has been isolated from fresh root tubers of the plant. It was found to express protein polymorphism separated by ion-exchange chromatography. 7 , 8 Three Japanese studies report structure and anti-inflammatory effects of five hydroxylated sterols from Chinese cucumber seeds. 9 , 10 , 11

Uses and Pharmacology

Abortifacient
Animal data

Extracts of the plant have been known for centuries to be potent abortifacients. Trichosanthin inhibits ribosome activity and cellular replication. 12 Trichosanthin inactivates ribosomes by cleaving the N-C glycosidic bond of adenylic acid at position 4324 of 28S rRNA in a hydrolytic fashion. 13 Another report discusses the importance of lysine and arginine to trichosanthin's activity. 14 Another ribosome-inactivating protein, beta-kirilowin, has recently been isolated from T. kirilowii seeds and exhibits strong abortifacient activity. 15 Studies on another abortifacient and antitumor protein, karasurin, report induction of midterm abortion in pregnant mice. 7 , 8 Other proteins present in the plant have been reported to express similar abortive effects. 16

Clinical data

Chinese cucumber juice, applied to a sponge inserted vaginally, can induce abortions. Trichosanthin has been used to abort ectopic pregnancies in place of management via salpingectomy. 17 The drug is also effective in inducing first-trimester abortion when administered intramuscularly or extra-amniotically. 17

Antitumor
Animal data

Trichosanthin selectively kills choriocarcinoma cells 18 and also shows specificity as an antihepatoma agent. 19 Trichosanthin is a reported potent immunosuppressive protein, which could affect various cell-mediated processes. 20 The plant's other components, karounidiol and bryonolic acid, have been evaluated for their cytotoxic activity. 21 , 22 , 23

Clinical data

Trichosanthin possesses antitumor activity and has been used to treat invasive moles. 2 , 24

Anti-HIV
Animal data

Research reveals no animal data regarding the use of Chinese cucumber as an anti-HIV agent.

Clinical data

The Chinese cucumber has gained enormous popularity because trichosanthin may be effective in the management of acquired immunodeficiency syndrome (AIDS) infections. A report by McGrath, et al, described the ability of GLQ-223 to block HIV replication in infected T-cells and to kill HIV-infected macrophages. In vitro, this compound appears to selectively kill infected cells without damaging uninfected cells. Trichosanthin also appears to prevent the HIV virus from replicating in T-4 cells (immune cells that are killed by the virus). When freshly drawn blood samples from HIV-infected patients were treated with a single 3-hour exposure to GLQ-223, HIV replication was blocked for at least 5 days in subsequently cultured monocytes and macrophages. 25 Human clinical trials have been initiated in the United States to determine the drug's potential in man.

A report studied anti-HIV activity in trichosanthin purified from T. kirilowii root tubers. 26 A protein (“TAP 29”), distinct from trichosanthin, may offer a broader safe dose range compared with trichosanthin in AIDS treatment. The two proteins exhibit similar anti-HIV activity. 27

Other uses

Other immunological effects of trichosanthin include: Initiation of the alternative complement activation pathway in mice; 28 viability of human immunocytes, lymphocyte proliferation and cytotoxicity to lymphoma and leukemia cell lines; 29 and inhibitory effects on IL-8 induction in lipopolysaccharide-activated rat macrophages. 30 Other effects of Chinese cucumber in animals include: Inhibition of inflammation, 9 ulceration, 31 and hypoglycemia. 32

Dosage

There is no recent published clinical evidence to guide dosage of Chinese cucumber. It is most commonly administered as part of a polyherbal preparation in TCM.

Pregnancy/Lactation

Documented adverse effects. Avoid use. 1

Interactions

None well documented.

Adverse Reactions

Patients who receive injections of trichosanthin for abortion often develop strong sensitization to the compound. The risk of anaphylactic reaction secondary to a single exposure to trichosanthin may last longer than a decade. 2

Other severe reactions produced by trichosanthin include pulmonary and cerebral edema, cerebral hemorrhage and myocardial damage. One report describes six patients with AIDS who purchased a cucumber root extract while in China. Following parenteral administration, the patients developed seizures and fever and were hospitalized. 24

An additional study reported increased incidence of follicular atresia, ovulation changes and decreased hormone levels in mice given trichosanthin injections. 33

Toxicology

Extracts of the Chinese cucumber are extremely toxic, particularly if administered parenterally. Subacute LD-50 studies in mice resulted in deaths in 10 days. The LD-50 of intravenously administered freeze-dried root extract was 2.26 mg/mouse. Crystalline trichosanthin had an LD-50 of 0.236 mg/mouse.

The FDA has received a report of a patient who died following trichosanthin injections. 2 The crude mixture of plant proteins and lectins may have resulted in damage to blood cells. Clinical trials in the United States are confined to the use of highly purified trichosanthin.

Chinese cucumber use is contraindicated in pregnant women. Abortifacient effects have been well documented. 7 , 8 , 12 , 15 In vivo and in vitro teratogenic effects were evaluated in mice, resulting in aphysical abnormalities. 34

Bibliography

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