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APOCYNACEAE(Dogbane or Vinca family)• Medicinal / Folk-medicinal aspects: Many species have found use in traditional medicine, such uses ranging from the removal of warts to the treatment of eczema and itch, to wound healing and the treatment of ophthalmia. • Mabberley (2017) noted that the family comprises 4675 species in 345 genera. Plants of the World Online recognises 379 genera.a The plant families Asclepiadaceae and Periplocaeae, formerly considered to be distinct, are now subsumed into the Apocynaceae. Most of the species occur in the tropics, but a few are of common occurrence in temperate regions. Most contain a white latex, some having yellow or red latex. This large family is of considerable economic importance, many species yielding useful timbers, others being cultivated for their fibre. Many contain medicinally useful indole alkaloids and cardiac glycosides for which they are cultivated commercially. Some may be found in collections of succulent plants, for example Ceropegia L., Huernia R.Br., and Stapelia L. species; some are grown in temperate climates as border plants, for example Asclepias L. and Vinca L. species. Oleanders (Cascabela thevetia (L.) Lippold, Nerium oleander L.) and allamandas (Allamanda cathartica L.) and hoyas (Hoya L. species) are widely cultivated as ornamental shrubs (Hunt 1968/70). Those who grow epiphytic myrmecophytes as curiosities may also include Dischidia R.Br. and Hoya L. species in their collections. The leaves of Gymnema sylvestre R.Br. contain gymnemic acid, the term used to describe a mixture of triterpenoid saponins of closely related structure, which has the capacity to obtund taste for several hours for sweet, but not bitter, sour, astringent, nor pungent substances (Webb 1948a, Dateo & Long 1973).
Gardner & Bennetts (1956) include Acokanthera spectabilis in a list of plants known or suspected of causing urticaria or skin irritation. Morton (1977), citing Hurst (1942), noted that contact with Acokanthera spectabilis may cause smarting of the eyes and skin, and throat irritation. According to Watt & Breyer-Brandwijk (1962), an ointment made from the fine scrapings of the root of Acokanthera spectabilis is used by the Mpondo for the relief of itchy conditions. The application is said to be violently irritant.
Contact with Acokanthera venenata may cause smarting of the eyes and skin, and throat irritation (Hurst 1942, Morton 1977). The wood of this tree, which is found in tropical East Africa, is the source of an extremely potent arrow poison. The poisonous principle is ouabain, a cardiac glycoside otherwise known as G-strophanthin, which is used clinically by intravenous injection. The compound is also present in Acokanthera longiflora Stapf, Acokanthera schimperi Oliver, and Acokanthera venenata G.Don, as well as Strophanthus gratus Baill. (Wade 1977, Hausen 1970).
Adenium Obesum Leaf Extract, Adenium Obesum Leaf Cell Extract, & Adenium Obesum Callus Cuture Extract [INCI; of uncertain composition (see Schmidt 2017)] are recognised cosmetic product ingredients purported variously to have skin conditioning, skin protecting, fragrancing, humectant, hair conditioning, and antioxidant properties (Standing Committee on Cosmetic Products 2019, CosIng 2023). [Further information available but not yet included in database]
This climbing plant is a native of tropical South America, but is widely cultivated as an ornamental species for its flowers. Several authors, including Allen (1943), Blohm (1962), Morton (1971), and Hardin & Arena (1974) refer to the capacity of this plant to cause irritant dermatitis. The orthographic variant name Allemanda cathartica is also encountered in the literature. [Further information available but not yet included in database]
The wood of these species is said in the trade to be irritant (von Wendorff 1964). South American Indians of the north-west Amazon have applied the latex of this species to the scalp as a treatment for ringworm (Schultes 1979). The latex has been found to produce a slightly painful oedematous swelling on application to the shaven ear of the rabbit. A serum-like fluid exudes on the surface of the swollen area and forms a yellowish scab which persists for some time. The latex has also been used as a local application to warts (Watt & Breyer-Brandwijk 1962). Bull & Burrill (2002) also refer to the skin irritant properties of the milky sap. The common names of this plant refer to the property that the flowers have of trapping pollinating insects. Because of this, the plant is sometimes erroneously described as insectivorous. There are about 120 species, most of which are natives of the Americas, particularly the USA. Some are widely cultivated in Europe as border plants. The plants contain cardiac glycosides which render them poisonous on ingestion (Lewis & Elvin-Lewis 1977). Several species have been found to contain proteinases in their latex. The latex is employed by Nevada Indians to treat ringworm (Train et al. 1957). The plant's milky latex will produce dermatitis in susceptible individuals (Allen 1943, Blohm 1962). According to Shelmire (1940), Asclepiodora viridis is only an infrequent sensitiser, but no clinical detail was provided. A proteinase, named asclepain m, has been isolated from the latex of this species (Greenberg & Winnick 1940). The similarity of its properties to those of papain and bromelain was demonstrated. The latex is applied by Nevada Indians to remove corns and callouses (Train et al. 1957). A proteinase, named asclepain, has been isolated from the latex of this species (Winnick et al. 1940). The similarity of its properties to those of papain and bromelain was demonstrated. Carpenter & Lovelace (1943) purified a proteinase, named asclepain, from the roots of this species. Lynn et al. (1980) demonstrated that the asclepain from this species consists of two series of compounds each consisting of five separate proteinases which they named asclepain A1, A2, A3, A4, & A5 and asclepain B1, B2, B3, B4, & B5. The powdered root, when applied to the skin, is escharotic (Piffard 1881). The 80 species in this genus are natives of tropical South America and the West Indies. Many species provide durable timber, resistant to fungal decay and weathering. These include (Hausen 1973, 1981):
The terms peroba da campos and peroba amarella are also applied to the somewhat similar but botanically distinct timber from Paratecoma peroba Kuhlm. (syn. Tecoma peroba Rec.) in the family Bignoniaceae. The freshly cut wood and sap of Aspidosperma species causes irritation of the eyes, nose, and throat, with general malaise. The sawdust, on contact with abraded skin, produces local burning and a vesicular eruption with general symptoms of muscular weakness and cramps, sweating, dryness of the mouth, and faintness. Once the wood is thoroughly dry it loses its toxicity unless polishes or dyes in organic solvents are used on it (Freise 1932, 1937). Orsler (1969) received trade reports of irritation of the skin and respiratory tract in England from peroba rosa. Aspidosperma species contain a wide variety of indole alkaloids which, on the basis of pharmacological studies carried out on the alkaloids of Aspidosperma quebracho-blanco bark (Dixon & Ransom 1924), are responsible for toxic effects on the nervous, respiratory, and circulatory systems. A recent report of eczema of the hands in a young female manicurist (Brun 1978) was ascribed to "orange wood" cuticle sticks following epicutaneous testing of various products used at her place of work. The wood was subsequently identified as pau marfim — an Aspidosperma species. According to Hausen (1981), sensitisation experiments on guinea pigs revealed a strong sensitising capacity, but the quebrachine-type alkaloids in the wood do not appear to be the allergens. Schultes (1979) reports that the fruits of this species, when reduced to ashes and mixed with oil of patabá from Jessenia polycarpa H.Karst. (fam. Palmae), may be used to lighten dark skin. The wood dust has caused dermatitis in sawyers (Peckolt 1909).
This species, and Calotropis procera W.T.Aiton, provides the crown flowers of Hawaiian "leis" and in this capacity can be violently irritant (Arnold 1968). The latex is irritant, caustic, and depilatory when applied to the skin or mucous membranes (Chopra et al. 1960, Morton 1962, Blohm 1962, Behl et al. 1966, Nadkarni 1976). In contact with the eye, the latex causes severe irritation, a burning sensation, swelling of the eyelids, and blurring of vision from corneal oedema (Muthayya 1948, Wong 1949, Crawford 1958, Sugiki 1966), an outcome that has been exploited by malingerers (Duke-Elder & MacFaul 1972b). Recovery is spontaneous and complete, requiring no specific treatment (Grant 1974). Nadkarni (1976) describes how various parts of this plant are used in Indian traditional medicine in the preparation of remedies for the treatment of skin diseases. For example, the root bark reduced to a paste with sour congee [rice vinegar] is applied to elephantiasis of the legs and scrotum; a powder of the dried leaves is dusted on wounds and ulcers to destroy excessive granulation; and the milky juice is used for ringworm of the scalp, to destroy piles, and is applied to ulcers to hasten healing. As well as containing calotropin and other cardiac glycosides, the latex contains several proteinases. Abraham & Joshi (1979a, 1979b) describe two carbohydrate containing proteinases, calotropain FI and FII, the former being very similar in its properties to chymopapain, whilst the latter more closely resembles papain. Pal & Sinha (1980) also describe the isolation of two other papain-like proteinases, calotropains DI and DII that do not contain carbohydrate, and the detection of a further three proteolytic enzymes. The plant may be found in cultivation for the strong fibre from its bark, and the silky hairs from its seeds.
Morton (1962a) asserted that the milky sap is caustic and irritant on skin, and may cause swelling and ulceration. The milky juice has also been described as rubefacient by Irvine (1961), and as a depilatory by Morton (1962a). Singh et al. (1978) observed irritant effects in all six contact dermatitis patients patch tested with the leaf crushed in normal saline. Williamson (1955) also reports the caustic nature of the plant. According to Wren (1975), the bark is used as a local remedy in India for elephantiasis, leprosy and chronic eczema. Nadkarni (1976) records that the medicinal properties of the plant are similar to those of Calotropis gigantea, and that the milky juice (latex) has been used as a blistering agent. Its use in India in the treatment of skin diseases has caused severe bullous dermatitis leading sometimes to hypertrophic scars (Behl et al. 1966). The local effect of the latex on the conjunctiva is congestion, epiphora, and local anaesthesia. It has occasionally been used to produce such symptoms by malingerers (Dalziel 1937). Referring to Asclepias procera, Giday et al. (2003) recorded that the stem latex of this shrub is used in the traditional medicine of the Zay people in Ethiopia as an externally-applied remedy for haemorrhoids. They noted also that the latex is applied as a remedy for black leg [= an infectious and usually fatal bacterial disease of sheep and cattle caused by Clostridium chauvoei or, less commonly, Clostridium feseri]. The latex of this species is similar to that of Calotropis gigantea in its content of proteinase and also calotropin and other cardiac glycosides (Watt & Breyer-Brandwijk 1962). Atal & Sethi (1962) isolated calotropain from the latex and showed it to be a mixture of at least five proteinases. The proteolytic activity of calotropain was greater than that of papain, ficin, or bromelain.
Both of these tropical American species are irritant and toxic (Standley 1927, Schwartz et al. 1957, Hausen 1973). Record & Hess (1943) refer to the reputed burning and inflammation of the skin from contact with the sap of C. latifolia and also C. angustifolia L. Dahlgren & Standley (1944) note that the blistering sap of C. latifolia causes severe inflammation. von Reis Altschul (1973), referring to C. belizensis, states that the plant is seldom collected probably because people are afraid of it, and with good reason. This genus comprises some 35 species of shrubs with branch thorns. They occur in warm regions of Africa and Asia, and are occasionally cultivated as greenhouse shrubs. Some bear edible fruit. This thorny shrub has irritant latex (Burkill 1935). This plant is a common weed throughout the tropics. It is the source of the so-called vinca alkaloids, vincristine and vinblastine, used in cancer chemotherapy. Patch tests carried out using the leaves of this species crushed in a small quantity of normal saline elicited no positive reactions in 11 contact dermatitis patients tested in New Delhi, India (Singh et al. 1978). A case has been described where a solution of vinblastine intended for intravenous injection was accidentally squirted in the eye. This caused epiphora associated with diffuse keratitis epithelialis (Grant 1974).
Corner (1952) believed that C. manghas and C. odollam were distinct species that were easily distinguished by the shape and colour of the flowers and the structure of the seeds, the former being the pink-eyed cerbera and the latter the yellow-eyed cerbera. The use of the colloquial name buta buta for both Excoecaria L. (fam. Euphorbiaceae) and some Cerbera species has led to the latter being falsely associated with the intensely irritant and blinding properties of the former (Burkill 1935, Corner 1952). This error may have been made by von Reis Altschul (1973) who noted that the white latex causes blindness if allowed to come into contact with the eyes.
[Information available but not yet included in database] Nadkarni (1976) noted that the leaves of this woody climber are used in Indian traditional medicine to cure ulcerous sores.
This plant, found in West Equatorial Africa, forms a slender twining shrub which may climb up to the tops of forest trees (Irvine 1961). In Nigerian traditional medicine, the latex is applied to tumours and other swellings, and the powdered root is applied in the treatment of snake bite (Ainslie 1937). Irvine (1961) recorded that the leaves, which cause a burning sensation, are applied to heal wounds in French Equatorial Africa. He also noted that the young scorched leaves are rubbed on the skin in Sierra Leone for craw-craw, and that the Mende [of Sierra Leone] use the latex for [unspecified] skin trouble.
When the vine is dry, a fine powdery dust which emerges causes violent coughing, swelling of the nose and blistering of the eyelids. Not all individuals are affected (White 1923, Morton 1958). The acrid sticky milky sap is a drastic irritant to the skin. Gloves should be worn when pruning or working with the plants (Oakes & Butcher 1962). Hardin & Arena (1974) included this species in a list of plants known or suspected to cause dermatitis. Several species growing epiphytically in their natural habitat are characteristically associated with "ant-gardens". If handled, the disturbance of these ant-gardens renders the intruder liable to attack by a swarm of ants; a pseudophytodermatitis caused by the bites and/or stings of these insects may be the outcome. The plants in such ant-plant relationships have been described as super-nettles. A review of this topic is provided by Schmidt (1985). Menninger (1967) provides a photograph of this myrmecophyte. Menninger (1967) provides a photograph of this myrmecophyte and of a section through one of its ant-inhabited "pitchers".
The sap and wood produced positive patch test reactions in six forest workers; the leaves produced negative reactions (Siregar 1975). The leaves of this species when pounded with rice (Oryza sativa L., fam. Gramineae) and turmeric (Curcuma longa L., fam. Zingiberaceae) have been used in Malaya to treat eczema and itch (Burkill 1935).
[Information available but not yet included in database] The wood causes symptoms similar to those produced by Aspidosperma species (Freise 1937). The hard timber from this South African tree has long been used as a substitute for European boxwood (Buxus sempervirens L., fam. Buxaceae) in the manufacture of shuttles, tool handles, and similar objects (Hausen 1981). Workers exposed to the dust of African boxwood developed alarming reactions including irritation of the eyes and nose, and also constitutional symptoms. Some developed asthma (Legge 1906, Legge 1908, Hay 1907). There is some confusion in the literature as to the botanical identity of the wood (Dixon 1911), it being initially believed that West African boxwood was the cause — see Nauclea diderrichii Merr., fam. Rubiaceae. In the UK, following a recommendation in the Samuel Report of 1907 (Samuel et al. 1907), Gonioma kamassi wood dust was added to the list of causes of occupational diseases for which compensation could be claimed under the Workmen's Compensation Act 1906. Only a few cases have been compensated since other woods have largely replaced this in the trade (MacKenna & Horner 1954). In Australia, the timber was recognised in 1916 as a cause of industrial injury for which compensation could be claimed (Maiden 1917). In the USA in 1920-1930s, occupational dermatitis caused by Knysna boxwood was compensated by law only in Minnesota (Hausen 1981a citing Ganzoni 1929). The latex is believed to be effective against warts (Schultes 1979). This plant occurs throughout the tropical rain forests in the region of southern Cameroun in western Africa. Its caulinary swellings are inhabited almost invariably by an aggressive species of ant (Tetraponera aethiops Smith, 1877, fam. Formicidae) with an exceedingly painful sting (Bequaert 1922). The consequence of handling the plant in its natural habitat, or even simply standing beneath its branches is likely be a pseudophytodermatitis caused by the bites and stings of the ant inhabiting this super-nettle. A review of this topic is provided by Schmidt (1985).
Nadkarni (1976) noted that in Indian traditional medicine a paste of the root is applied to cleanse and cure ulcers and swellings; also that the milky juice is dropped into inflamed eyes, causing copious lachrymation and afterwards a sense of coolness. The plant is also included in multi-ingredient medicines used to treat various chronic diseases of the skin.
The crude drug known variously as Kurchi, Conessi Bark, Tellicherri Bark, Holarrhena Bark, or Zhi Xie Mu derived from Holarrhena antidysenterica has been used in India and elsewhere in the treatment of amoebic dysentery. It contains conessine, a steroidal alkaloid that may be extracted from both the bark and the seeds (Remington et al. 1918, Todd 1967). Research workers involved in the isolation of conessine from this plant, and in structural studies of the compound, have suffered from a contact dermatitis which was thought to be of an allergic nature (Jewers 1981). There is much confusion in the literature as to the botanical identity of the crude drug, with many authors identifying Wrightia antidysenterica R.Br. as the source. This confusion was alluded to by Brown (1922) who cited an earlier article published in the Indian Medical Gazette in 1880. [Information available but not yet included in database] Referring to Zschokkea aculeata, Freise (1937) noted that the wood of this South American tree produces symptoms of poisoning in wood-workers similar to those produced by Aspidosperma Mart. & Zucc. species. Quattrocchi (2012) noted that the trunk of this tree is covered with blunt prickles or conical-shaped spines.
The wood causes symptoms similar to those produced by Aspidosperma species (Freise 1937).
Sóti et al. (1967) isolated conessine from Malouetia tamaquarina. Conessine is believed to have caused contact dermatitis in research workers [see Holarrhena antidysenterica above].
The latex of these two species is caustic and has been used by South American Indians to remove warts (Schultes 1979). The latex is said to have depilatory properties (Schultes 1979).
These species have caustic latex (Schultes 1979). The juice of this south-eastern European species blisters the skin (Howes 1974).
Stuart (1911), referring to Metaplexis stauntoni, noted that in Chinese traditional medicine, the plant is known as lo mo or huan lan. Its seeds when crushed are used as an astringent and haemostatic application to wounds and ulcers. They are also applied to all sorts of insect bites but are thought to have escharotic properties if used too frequently. Perry & Metzger (1980), referring to Metaplexis japonica, state that the crushed seeds may be caustic.
The genus Nerium L. comprises a single species of which about 400 cultivars are known (Mabberley 2008). This variability has evidently contributed to some taxonomic confusion in the early dermatological literature. Oleander is a source of cardiac glycosides, which render the plants extremely poisonous on ingestion. Oleandrin obtained from Nerium oleander L. is used similarly to digitalis (Wade 1977). Although its toxicity has been long known (see Watt & Breyer-Brandwijk 1962, Hausen 1981a), cases of accidental poisoning continue to occur (Jaspersen-Schib et al. 1996). Smoke from a fire of oleander wood is toxic (Allen 1943, Hurst 1942), and meat cooked on oleander skewers or over an oleander wood fire may become poisonous (Steyn 1934, Burkill 1935, Francis & Southcott 1967). In Florida, the burning of oleander trimmings is prohibited in some communities (Morton 1958). Honey made from the nectar is also reportedly toxic (Pammel 1911). Notwithstanding its toxicity, this shrub is widely cultivated for its attractive flowers (Mabberley 2008). It is grown outside in warmer climates, and as a house or greenhouse plant in cooler regions (Hunt 1968/70). In relation to the frequency with which exposure to oleander occurs, rather few cases of dermatitis have been reported. In 1817, Bigelow wrote that the common oleander is said to affect some persons like poison ivy (Toxicodendron Mill. species, fam. Anacardiaceae), and Halsted (1899) reported similar effects. Piffard (1881) noted that local application of the crude drug to healthy skin produces vesication. The assertion made by Morton (1958) that "sensitive individuals contract dermatitis from contact with the plant" probably derives from this earlier literature. More recent reports (Dorsey 1962, Behl et al. 1966) concern mainly children who have been playing around the shrubs. According to Behl et al. (1966), the sap of Nerium indicum is irritant, and circumstantial evidence suggests that it may contain a sensitiser. Patch tests carried out using the leaves of Nerium odorum crushed in a small quantity of normal saline elicited positive reactions in 3 of 8 contact dermatitis patients tested in New Delhi, India (Singh et al. 1978). Hjorth (1968) obtained no positive patch tests to Nerium oleander in seven patients studied. Dragendorff (1898), cited by Steyn (1934), recorded that the leaves and bark are used externally in eczemas. According to Felter & Lloyd (1898), pediculi are destroyed by a decoction of the leaves. Muenscher (1951) noted that the leaf has been used in northern Africa in the treatment of scabies, but was also reported to produce dermatitis. Nagata (1971) records the use in Hawai‘i of Nerium indicum in the treatment of skin diseases. Extracts of Nerium odorum roots have been used in Indian indigenous medicine in the treatment of leprosy and other skin diseases (Nadkarni 1976). [Further information available but not yet included in database]
In Indian traditional medicine, a decoction of the plant is used as a gargle and mouthwash in the treatment of sore throat and aphthous ulcers (Nadkarni 1976). This genus comprises 25 species found mainly in Madagascar but also in southern and south-western Africa (Mabberley 2008). A number may be found in collections of succulents. Some are exceedingly thorny, their trunks and branches completely covered with spines. The following species are spiny (Hutchinson 1946; Chittenden 1951; Findlay 1962; Menninger 1967; Palgrave 1956):
Whilst Hunt (1968/70) states that Pachypodium giganteum Engl. is spiny, Menninger (1967) describes this species as fat and ugly and having no thorns. This climber found in South East Asia and Malaysia yields Balsamo de Tagulaway, otherwise known as Cebur Balsam or Cebu Balsam, which is prepared by extracting the bark and leaves with hot coconut oil. The peculiarly odorous yellow-white liquid so obtained is applied to wounds and cutaneous affections (Felter & Lloyd 1898).
Referring to Daemia extensa, Nadkarni (1976) noted that this twining plant is extremely irritant, but no further detail is given. He noted also that in Indian traditional medicine, the fresh leaves made into a pulp are used as a stimulating poultice for carbuncles; also the juice of the leaves is employed in the preparation of a medicinal oil used in rheumatism. Nadkarni (1976) noted that the milky juice is used in traditional medicine for swellings. Members of this genus are typically small to medium sized trees which contain latex. They are widely cultivated in tropical regions. Both Allen (1943) and Morton (1962a) noted that Plumeria species contain a somewhat caustic milky latex which, if allowed to remain on the skin, may cause a rash or even blistering in sensitive individuals. Standley (1927) did not find the latex irritant on his own skin. The pleasantly fragrant flowers of various species and hybrids are used in Hawai‘i for flower garlands (known as leis) which cause no trouble except in susceptible individuals (Arnold 1968). The flowers are also offered in Buddhist temples (Willis 1973). Many species previously included in the genus Plumeria are now considered to belong to the genera Coutinia Vell. or Himatanthus Willd.
The latex is rubefacient and corrosive (Allen 1943, Behl et al. 1966). It has been used in the treatment of warts (Watt & Breyer-Brandwijk 1962).
The latex is described as irritant by Allen (1943). Both Quisumbing (1951), referring to Plumeria acuminata, and Perry & Metzger (1980), referring to Plumeria rubra, state that the latex is rubefacient. Corner (1952) also considered Plumeria acuminata and Plumeria rubra as separate species, but principally as a convenient means by which pink and red-flowered varieties of frangipani could be distinguished from white-flowered varieties. It should be noted that the botanically unrelated Hymenosporum flavum F.Muell. (fam. Pittosporaceae) is known by the common names frangipani, Australian frangipani, and woollum. This genus is the source of the rauwolfia alkaloids, and in particular reserpine which is used medicinally as an antihypertensive and sedative. The two species of greatest importance in this respect are R. vomitoria Afzel. and R. serpentina Benth. See also Vinca minor L. The latex is said to be irritant to susceptible subjects (Standley 1927). The wood causes symptoms similar to those produced by Aspidosperma species (Freise 1937). The milky sap of this plant is irritant (Oakes & Butcher 1962). 2,6-Dimethoxy-1,4-benzoquinone, a known contact allergen, has been reported to occur in this species (Hausen 1978a). In the Solomon Islands, the sap has been mixed with coconut oil and rubbed on the skin to blister it (Kajewski 1895). The copious latex is said to be vesicant in susceptible subjects (Allen 1943). This species has caustic sap (Hurst 1942, Webb 1948a) which blisters human skin (Everist 1972). The milky juice has been used to treat corns and warts, and has been used as a healing application to wounds (MacPherson 1932). The plant is said to produce urticaria on contact with the skin (Watt & Breyer-Brandwijk 1962). The timber derived from this tree is known as pegojo. It is used locally for general purposes in Central America (Hausen 1973) and in the West Indies. Pardo-Castello (1923) noted that it has caused dermatitis, apparently with systemic toxicity. The wood is used in West Africa; the latex is caustic (Irvine 1961).
A female flower vendor, who held chandee flowers between four fingers of her left hand to thread garlands, developed a bullous eruption; a patch test produced bullae and ulceration (Behl & Captain 1979). Nadkarni (1976) notes that in Indian indigenous medicine "the milky juice of the leaves is dropped in the eye to cure ophthalmia; also a cooling application to irritable surfaces, to wounds to prevent inflammation". Jaffé (1943) isolated a proteolytic enzyme from the sap of the bark and green fruit of this Venezuelan shrub. It was named tabernaemontanain, and was found to resemble papain in its properties but was several times as active.
Cava et al. (1968) isolated (±)-vincamine and (+)-vincamine from the bark of Tabernaemontana rigida. Vincamine has caused contact dermatitis in the pharmaceutical industry [see Vinca L. and Vinca minor L. below]. Tabernaemontana macrophylla has been identified as the source of a timber known as pequerete, which is used in Brazil for constructional work (Hausen 1973). It produces effects similar to those produced by Aspidosperma species (Freise 1937). According to the Wood Explorer Database (http://www.thewoodexplorer.com/; accessed February 2010), pequerete is derived from Tabernaemontana citrifolia L., a more northerly species found in Central America and the West Indies. The poisonous seeds have a long history as an ordeal poison (Lewis & Elvin-Lewis 1977), their usefulness being associated with the cardiac glycosides that they contain. On the Malay Peninsular, the oil from the seeds has been rubbed on the skin as a rubefacient, and as a cure for itching. It has also been applied to the hair as an insecticide (Burkill 1935).
According to Allen (1943), the milky latex of Thevetia nitida produces a skin rash in many individuals.
Referring to Thevetia neriifolia, Allen (1943) asserted that the milky juice will cause blistering and inflammation on contact with the skin of susceptible individuals. Morton (1958) similarly noted that the milky sap of Thevetia peruviana may cause dermatitis. Watt & Breyer-Brandwijk (1962) and Hurst (1942) record from the same source that the milky juice has been used as a vesicant. The cardio-active glycosides present throughout the plant render it dangerously toxic. Many human fatalities have been reported (Watt & Breyer-Brandwijk 1962, Lewis & Elvin-Lewis 1977, Morton 1958).
Felter & Lloyd (1898), referring to Thevetia yccotli, noted that the fruit of this tropical American tree is applied to haemorrhoids.
Ratnagiriswaran & Venkatachalam (1935) described how one of them was continuously affected with dermatitis during the extraction and isolation of the alkaloids from this plant, particularly with solutions of the alkaloids in ether, benzene, or chloroform. Eruptions appeared on the skin a day after exposure. Itching, subsequently erythema and oedema were experienced. The symptoms continued for a week then subsided. The alkaloids tylophorine and tylophorinine present in this species have since then often been described as vesicant (Govindachari et al. 1961, Gellert et al. 1962), but no formal skin testing appears to have been reported in the literature. This species has been used in Indian medicine for the treatment of asthma and bronchitis, and as an expectorant (Nadkarni 1976).
Both of these species contain tylophorinine, the latter also containing tylophorine (Phillipson et al. 1974). These alkaloids have been described as vesicant [see Tylophora asthmatica above]. The skin vesicant action of this species has been described as less pronounced than that of Tylophora asthmatica (Gellert et al. 1962). It contains tylophorine and tylocrebrine (Phillipson et al. 1974). The five species retained in this genus are natives of Europe, western Asia, and northern Africa, but some are widely naturalised. Certain species formerly included in this genus are now differentiated as Catharanthus species, and this has led to some confusion with regards to the source of the so-called vinca alkaloids used in medicine (see also Catharanthus). A Vinca species has been listed as a sensitiser (Shelmire 1940). Van Hecke (1981) reports a case of allergic sensitivity to vincamine tartrate in a pharmaceutical industry worker who exhibited airborne eczematous contact dermatitis to an unnamed Vinca species. Vinca major L. is very commonly found in gardens in Britain, and is used in herbal medicine as an astringent. No proven cases of dermatitis attributable to this species have been reported. Eighteen from 48 workers employed in the pharmaceutical industry preparing vinca alkaloids developed contact dermatitis (Valér 1965). Sensitivity to the crude alkaloid extract from the plant was demonstrated. Cross sensitivity to ajmaline, reserpine (both being indole alkaloids), and tryptophan, but not to ergot alkaloids was demonstrated. Vincamine is the major alkaloid of Vinca minor, but also occurs in V. major L., V. difformis Pourret, V. herbacea Waldst. & Kit., and V. erecta Regel & Schmalh. (Taylor & Farnsworth 1973). It is used clinically as an hypotensive agent.
The roots of Vincetoxicum officinale have been found to contain tylophorine (Pailer & Streicher 1965), an alkaloid that has been described as being vesicant [see Tylophora asthmatica above].
This plant has been confused with Holarrhena antidysenterica Wall. ex A.DC. as the source of the crude drug kurchi. See Holarrhena pubescens Wall. ex G.Don above. References
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