Are four o'clock flower seeds really abortifacient?

Only partly. The seeds of the four o'clock flower (Mirabilis jalapa), which are poisonous, are the part of the plant richest in ribosome-inactivating proteins, a family in which one member, MAP, ended pregnancy in pregnant mice. No study demonstrates this effect in women, and eating the seeds mainly causes digestive upset: they are neither a reliable abortifacient nor a safe product.

Substance pharmacologytoxicologybotanyhistory-of-science

Four o'clock flower seeds: poisonous and abortive?

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Called to the bedside of a sick servant, Maomao notices in the pavilion garden a bed of four o’clock flowers with pure white blooms. The choice passes for a matter of feng shui, where green and white would be pledges of good health, but she sees something else: the white powder inside the seeds of this plant is used as an abortifacient. She links this clue to the oils brought in by the caravan and concludes that the flowers were planted on purpose. A few days later, on spotting other four o’clock flowers, Maomao remembers that the courtesans of the pleasure district used to gather the seeds to compound an abortifacient, mixed with ground cherry, garden balsam, peonies and quicksilver.

The subject in depth

What is the four o’clock flower?

The four o’clock flower, Mirabilis jalapa, also called marvel of Peru, is a herbaceous plant of the Nyctaginaceae family, native to the dry tropical regions of Mexico, Central America and South America ^[Wikipedia]. Its flowers open in late afternoon and stay open all night, hence its English name “four o’clock” and its French name “belle-de-nuit”, the night beauty. A single plant can bear pink, yellow, white or variegated flowers ^[Wikipedia]. Its fruit holds a single black, wrinkled seed, which contains a white, floury reserve.

Diagram of a four o'clock flower seed cut in half: a wrinkled black shell, a white powder inside leading on one side to face powder, on the other to a protein that blocks the ribosome, with the note tested in mice, never in women. — One powder, two reputations

Are four o’clock flower seeds poisonous?

Yes, but moderately. The poisonous four o’clock flower seeds and its roots are the parts of the plant recognized as toxic. Eating them mainly causes abdominal pain, nausea, vomiting and diarrhea, and handling the roots can irritate the skin ^[Web]. The root is purgative and emetic, which earned it an old medical use as a laxative ^[Wikipedia]. The compound responsible for these digestive troubles has not been formally identified.

Which molecule could act on a pregnancy?

The strongest lead is a family of plant enzymes, the ribosome-inactivating proteins . The ribosome is the workshop where the cell assembles its proteins. These enzymes pull out a tiny part, an adenine of the ribosomal RNA, and the workshop shuts down. Ricin belongs to the same family. In the four o’clock flower, an Italian team measured this activity in every tissue of the plant: it peaks in the seed ^[Étude]. The main protein is called MAP, for Mirabilis antiviral protein, because it was first studied for its action against plant viruses.

In 1992, biochemists in Hong Kong purified MAP from the roots and observed that it ended pregnancy in mice ^[Étude]. This result is explained by analogy with a well-known related protein, trichosanthin.

Why does this mechanism target the placenta?

Trichosanthin, extracted from the root of a Chinese gourd, is the active ingredient of Tian Hua Fen powder, used as an abortifacient in Chinese medicine. It was purified in 1972 to reduce its side effects ^[Étude]. It preferentially destroys the cells of the trophoblast , the layer that forms the placenta: deprived of its nourishing cells, the embryo can no longer be sustained. The four o’clock flower’s MAP belongs to the same family, which makes a comparable effect plausible.

Two limits nevertheless separate this plausibility from real effectiveness. Proteins are largely broken down by digestion, and the medical use of trichosanthin relied on injection (intramuscular, intra-amniotic or intrauterine) ^[Étude]. Moreover, no study has measured the effect of four o’clock seeds swallowed by a pregnant woman. The rest of the seed, with its digestive irritants, acts on the mother long before reaching any placental target.

In real life

Brought to Europe in 1525 ^[Wikipedia], the four o’clock flower traveled on to Asia, where it became a common garden flower. Its Japanese name, oshiroi-bana, means “white powder flower”: the floury reserve of its seeds recalled the foundation powder of geishas, and the crushed seed was used as face powder ^[Wikipedia]. In China, its folk names, “shower flower” or “rice-cooking flower”, recall the evening hour at which it opens ^[Wikipedia]. In Mexico and Brazil, its leaves and roots go into traditional remedies for pain and digestive troubles. Its epithet jalapa evokes jalap, a famous Mexican purgative that European apothecaries long wrongly attributed to it, although it comes from another plant ^[Wikipedia]. The plant also left its mark on genetics. Around 1900, Carl Correns used it to study cytoplasmic inheritance . It is also a textbook case of incomplete dominance: crossing a plant with deep pink flowers and a plant with white flowers gives light pink flowers ^[Wikipedia].

The fact-checker's eye

Verdict: plausible. The episode points to the right part of the plant, the seed, which concentrates both the toxicity and the ribosome-inactivating proteins. The idea that it could harm a pregnancy rests on a real mechanism, demonstrated in animals for MAP and in humans for its cousin trichosanthin.

What the series simplifies is the white powder itself. Nothing indicates that the floury part of the seed, the one used as face powder, carries most of the activity, nor that taking it by mouth works. The courtesans’ mixture also adds quicksilver, whose “abortifacient” effect comes from general poisoning of the mother, as explained in the entry on mercury. As with emmenagogue plants, these recipes first exposed the woman to poisoning, with no guarantee regarding the pregnancy ^[Wikipedia].

If four o’clock flower seeds or roots are swallowed, especially by a child or a pregnant woman, the right reflex is to contact a poison control center: in the United States, Poison Control at 1-800-222-1222; in the United Kingdom, NHS 111, or 999 in an emergency.

Going further

Emmenagogue and Abortive Plants, uterotonic activity and toxicity
Lead White Makeup, toxicology of cosmetic powders
Mercury, systemic toxicity of a liquid metal
Discipline: Pharmacology
Discipline: Toxicology

Glossary

Abortifacient ↗: Substance or method capable of ending a pregnancy. In pharmacology, the real, measured effect is distinguished from the reputation handed down by tradition.
Ribosome ↗: Molecular machine found in every cell, which reads messenger RNA to assemble proteins. Without working ribosomes, a cell can no longer make its proteins and eventually dies.
Ribosome-inactivating protein ↗: Plant enzyme that pulls out one specific base (an adenine) from the ribosome's RNA, which blocks protein production. Ricin is the best-known member of the family.
Trophoblast ↗: Layer of cells surrounding the embryo that forms the fetal part of the placenta. It ensures implantation in the uterus and exchanges with the mother.
Cytoplasmic inheritance ↗: Transmission of traits by elements located outside the cell nucleus, such as chloroplasts, usually through the maternal line only.

Sources

Mirabilis jalapa, French Wikipedia ^[Wikipedia]
Mirabilis jalapa, English Wikipedia ^[Wikipedia]
Mirabilis jalapa (Four O’Clock), North Carolina State University Extension ^[Web]
Bolognesi A. et al., Ribosome-inactivating and adenine polynucleotide glycosylase activities in Mirabilis jalapa L. tissues, J. Biol. Chem., 2002 ^[Étude]
Wong R. N. et al., Characterization of Mirabilis antiviral protein, Biochem. Int., 1992 ^[Étude]
Lu J.-Q., Wong K.-B., Shaw P.-C., A Sixty-Year Research and Development of Trichosanthin, Toxins, 2022 ^[Étude]
Abortifacient, French Wikipedia ^[Wikipedia]

Published on October 12, 2026

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Glossary

AbortifacientSubstance or method capable of ending a pregnancy. In pharmacology, the real, measured effect is distinguished from the reputation handed down by tradition.

RibosomeMolecular machine found in every cell, which reads messenger RNA to assemble proteins. Without working ribosomes, a cell can no longer make its proteins and eventually dies.

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Cytoplasmic inheritanceTransmission of traits by elements located outside the cell nucleus, such as chloroplasts, usually through the maternal line only.