Antiemetic African Medicinal Spices and Vegetables

The caatinga (semi-arid vegetation) is a Brazilian biome with a significant but poorly studied biodiversity closely associated with a diverse cultural heritage. The present work focused on analyzing published information available concerning medicinal plants used by traditional communities. We sought to contribute to future phytochemical and pharmacological investigations by documenting the therapeutic uses of native caatinga plants within the aims of modern ethnopharmacological research. Twenty-one published works cited a total of 389 plant species used by indigenous and rural communities in northeastern Brazil for medicinal purposes. The relative importance index (RI) of each species in these inventories was calculated, and information concerning the plant's local status (spontaneous or cultivated), distribution, and habit was recorded. Of the 275 spontaneous (non-cultivated) species cited, 15.3% were endemic to the caatinga. A statistical relationship was verified between the relative importance of the species and their endemic status (p<0.05). Herbaceous plants were more numerous (169) than trees (90) or shrubs and sub-shrubs (130) at a statistically significant level (p<0.05). A survey of published information on the phytochemical and pharmacological status of the plants demonstrating the highest RI supported the veracity of their attributed folk uses.

Ingestion of toxin, traumatic events, adverse drug reactions, and motion can all result in nausea and emesis. In addition, cyclic vomiting syndrome is quite prevalent in the pediatric population. Coordination of the various autonomic changes associated with emesis occurs at the level of the medulla oblongata of the hindbrain. Chemosensitive receptors detect emetic agents in the blood and relay this information by means of neurons in the area postrema to the adjacent nucleus tractus solitarius (NTS). Abdominal vagal afferents that detect intestinal luminal contents and gastric tone also terminate in the NTS (gelatinosus, commissural, and medial subnuclei). The NTS is viscerotopically organized into subnuclei that subserve diverse functions related to swallowing (subnucleus centralis), gastric sensation (subnucleus gelatinosus), laryngeal and pharyngeal sensation (intermediate and interstitial NTS), baroreceptor function (medial NTS), and respiration (ventrolateral NTS). Neurons from the NTS project to a central pattern generator (CPG), which coordinates the sequence of behaviors during emesis, as well as directly to diverse populations of neurons in the ventral medulla and hypothalamus. Thus, it is critical to realize that there is not an isolated "vomiting center," but rather groups of loosely organized neurons throughout the medulla that may be activated in sequence by a CPG. The newer antiemetic agents appear to block receptors in the peripheral endings of vagal afferents to reduce "perception" of emetic stimuli and/or act in the dorsal vagal complex. A primary site of action of 5-HT(3)-receptor antagonists is by means of the vagal afferents. Neurokinin-1 receptor (NK(1)R) antagonists are antiemetics, because they act at a site in the dorsal vagal complex. Part of their effectiveness may be the result of inhibition of the NK(1)R on vagal motor neurons to prevent fundic relaxation, which is a prodromal event essential for emesis. Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the major psychoactive component of marijuana, can be therapeutically useful as an antiemetic. The site of action of Delta(9)-THC is on cannabinoid CB1 receptors in the dorsal vagal complex. However, it decreases fundic tone and antral motility. It is not easy to predict the potential antiemetic effects of drugs that alter motility. Although antiemetic drugs are available for management of acute chemotherapeutic-induced emesis, few treatments are effective for delayed emesis or cyclic vomiting syndrome.