Canscora diffusa (PROSEA)
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Introduction |
Canscora diffusa (Vahl) R.Br. ex Roemer & Schultes
- Protologue: Syst. veg. 3: 301 (1818).
- Family: Gentianaceae
- Chromosome number: 2n= 36, 38, 60, 72, 84
Vernacular names
- Philippines: chang-bato, kobamba, malingal (Tagalog).
Origin and geographic distribution
C. diffusa has a very large area of distribution: it is widespread in tropical Africa, tropical Asia, tropical Australia and New Caledonia. In tropical Asia, it has been reported for Nepal, India, Sri Lanka, Vietnam, Laos, Thailand, Java (western part, scarce) and the Philippines (widespread), but probably it also occurs elsewhere.
Uses
In the Philippines, a decoction of the whole plant is used as a tonic and antigastralgic; it is used as a substitute for tea. C. decussata (Roxb.) Roemer & Schultes from tropical Africa, Madagascar and mainland tropical Asia (not in Malesia) is used in India as a laxative, alterative and nerve tonic; C. diffusa is sometimes used there as a substitute. C. lucidissima (H. Lév. & Vaniot) Hand.-Mazz. is used as a medicinal plant in China and Vietnam.
Properties
There is only one report on the phytochemistry and pharmacological activity of C. diffusa . The adaptogenic glucosyloxyflavan diffutin was isolated from whole plants. However, there is more information available on C. decussata . Tests showed that an aqueous extract of C. decussata promotes the adhesion of peripheral neutrophils to human umbilical vein endothelial cells. C. decussata contains xanthone C-glycosides. One of these, mangiferin, showed central nervous system depressant and anti-inflammatory activities. This compound also has antifungal activity, and proved useful for the control of Fusarium wilt in safflower ( Carthamus tinctorius L.). It showed some activity against Mycobacterium tuberculosis , but in general its antitubercular activity was low. Crude powder of C. decussata showed spermicidal activity in rats without any toxic side effects. A polyherbal preparation containing C. decussata enhanced performance in fattening pigs.
Furthermore, xanthones isolated from C. lucidissima showed activity against arrhythmia induced by myocardial ischaemia-reperfusion in tests with rats.
Botany
An annual, erect, glabrous herb up to 80 cm tall, much branched, with quadrangular branches. Leaves opposite, simple and entire, lower ones elliptical to elliptical-oblong, c. 4 cm × 1 cm, attenuate towards the base, 3(-5)-veined, upper ones shorter and cordate. Inflorescence a terminal cyme, usually combined into thyrses, lax, many-flowered; bracts ovate. Flowers bisexual, 4-merous, up to 1.5 cm long; pedicels up to 1.5 cm long; calyx tubular, 4-ribbed, with dentate lobes; corolla with cylindrical tube, lobes shorter than tube, unequal, pinkish; stamens inserted in the tube near the throat at different levels; ovary superior, 1-celled, style filiform with bifid stigma. Fruit an oblong capsule 4-7 mm long, many-seeded. Seeds small, c. 0.2 mm in diameter, testa minutely faveolate.
C. diffusa can be found flowering throughout the year.
Canscora comprises approximately 15 species and occurs in tropical Africa, Asia and Australia. South-East Asia is richest in species, with 7 species in Thailand.
Ecology
C. diffusa occurs on damp rocks, rocky crevices in stream beds in the forest, steep earth walls and old brick walls, up to 800 m altitude, but in the Philippines up to 1500 m.
Genetic resources
C. diffusa is very widely distributed and does not seem to be easily endangered by genetic erosion. However, nothing is known about its genetic variability.
Prospects
It might be promising to investigate whether the xanthones found in other Canscora species are also present in C. diffusa because of similar applications.
Literature
249, 278, 329, 585, 760, 842.
Other selected sources
62, 117, 274, 275, 276, 939.
Main genus page
Authors
R.H.M.J. Lemmens
