Gelsemium elegans 鈎吻

Loganiaceae 馬錢科

Gelsemium, Graceful Jesamine¹

胡蔓藤、斷腸草、大茶藥²

POISONOUS PARTS

Whole plant.³

TOXICITY

Toxic Constituents
Gelsemium alkaloids such as gelsemine, gelsenicine and humantenine.⁴
Toxic Dose
Reported lethal dose: 3 leaves.³
Mechanism
Not fully understood. One proposed mechanism is antagonization of the acetylcholine receptors.^5–7
Poisoning Features
Thirst, dry mouth, burning sensation in the throat and stomach, hyperthermia, sweating, headache, dizziness, blurred vision, mydriasis, palpitation, weakness, convulsion, respiratory depression , central nervous system depression and even death.^3–5
Poisoning Events
In China, mixing up the plant with other herbs has occasionally led to poisoning.⁴

CLINICAL MANAGEMENT

Supportive treatment.^5,8

IDENTIFICATION FEATURES

Woody climbers, up to 12 m or longer. Leaves opposite; leaf blades 5–12 × 2–6 cm. Thyrses densely flowered. Corolla yellow to orange, 1.2–1.9 cm long, funnelform, mouth with reddish spots; lobes 5. Capsules 10–14 × 6–8 mm, smooth. Seeds about 5.5 mm in diameter, winged.⁹

MEDICINAL USES

Highly toxic; use with caution. For external use only in TCM: dispel wind etc.^10–12

CASES IN TRL

In 2007, a woman was severely poisoned and required intubation after taking G. elegans collected in Lantau Island, which was misidentified as the non-poisonous Mussaenda pubescens. Similarly, a man was poisoned after misidentifying G. elegans (photo A) as non-poisonous “Bak-Lo-Sit” (Tadehagi triquetrum). In 2008, a family was intoxicated after taking a commonly used food item—roots of “Hairy Fig” (Ficus hirta), which were contaminated with roots of G. elegans. A handful of similar poisonings occurred in Hong Kong and China in the past few years.

In 2011 and 2012, 5 cases in 2 clusters presented with features of gelsemium poisoning after taking Cassytha filiformis collected from the hillside. The left-over plant was morphologically and genetically confirmed to be C. filiformis, which does not usually contain gelsemium alkaloids. Gelsemium alkaloids, however, were detected in the plant. We postulated that C. filiformis, being a non-toxic twining parasitic herb, absorbed gelsemium alkaloids from G. elegans which it lived on.