Centella asiatica (Linn) Urban known as
Indian pennywort is a prostate, perennial, faintly aromatic herb found wild throughout
India]. Leaves are used as tonic, memory enhancer and also used in the treatment of
cataract, eye troubles and in fevers and diarrhea among children. The plant is reported to
contain glycosides like brahmosides, indocentelloside, asiaticoside, theankuniside
and isotheankuniside. Asiaticoside, a trisaccharide triterpene, has been identified as
the most active compound in the plant associated with the healing of wounds and
duodenal ulcers, whilst the triterpene saponins are also reported to possess immunomodulatory
properties. Asiaticoside is one of the most active compounds which can serve as a
marker and is used for its standardization. A few methods such as gravimetric and
column chromatography have been suggested for the quantitative estimation of
asiaticoside which are not very precise, sensitive and require multiple step extraction
and purification. (http://www.science.cmu.ac.th/)
Interestingly, asiaticoside was shown to inhibit healing of experimental
corneal wounds in rabbits (Callizo et al. 1996).
Studies of the effect of asiaticoside in corneal wounds and ulcers have been
documented by Abou Shousa & Khalil (1967) and by Mekkawi (1968). Asiaticoside appears also to be able to inhibit collagen production in such a
way as to inhibit formation of hypertrophic scars, keloids, and stretch marks
(striae gravidarum / striae distensae) (Bosse et al.
1979, Qi et al. 2000, Widgerow
et al. 2000, Young & Jewell 2003).
Extracts from the plant have been formulated into several commercial products
including Collaven™, Emdecassol™, Madecassol™, Centelase™, Marticassol™,
Blastoestimulina™, and Trofolastin™. Reports of allergic contact dermatitis,
confirmed by patch testing have appeared sporadically following topical use of
Madecassol™, (Eun & Lee 1985), Centelase™ (Santucci et al. 1985, Vena &
Angelini 1986, Danese et al. 1994), and
Blastoestimulina™ (Izu et al. 1992, Aguirre et al. 1993, Bilbao et
al. 1995, Gonzalo Garijo et al. 1996).
Asiaticoside, asiatic acid, and madecassic acid appear to be the sensitisers (Huriez & Martin 1969, Hausen 1993). The
possibility of sensitivity to other components of the formulations (for example,
propylene glycol) should not be overlooked (Eun & Lee
1985, Hausen 1993). (http://botanical-dermatology-database.info/)
activity of Centella asiatica is thought to be due to
several saponin constituents, including asiaticoside,
asiatic acid, and madecassic acid. In vitro, each of
these compounds stimulated the production of human collagen
I, a protein involved in wound healing. Stimulation
of collagen synthesis in foreskin fibroblast monolayer
cultures by an extract from Herba Centellae has also
been reported. Asiaticoside accelerated the healing
of superficial postsurgical wounds and ulcers by accelerating
cicatricial action. Asiaticoside stimulates the epidermis
by activating the cells of the malpighian layer in porcine
skin, and by keratinization in vitro. Topical application
of asiaticoside promoted wound healing in rats and significantly
increased the tensile strength of newly formed skin.
Extracts of C. asiatica, and in particular its major
triterpene ester glycoside, asiaticoside, are valuable
in the treatment of hypertrophic scars and keloids.
Asiaticoside has been reported to decrease fibrosis
in wounds, thus preventing new scar formation. The mechanism
of action appears to be twofold: by increasing the synthesis
of collagen and acidic mucopolysaccharides, and by inhibiting
the inflammatory phase of hypertrophic scars and keloids.
It has further been proposed that asiaticoside interferes
with scar formation by increasing the activity of myofibroblasts
and immature collagen. (http://www.zeamais.com/)