Pennywort Centella asiatica Origin
Centella asiatica (CA) or Pennywort is a clonal, perennial
herbaceous creeper belonging to the family Umbellifere (Apiceae). This plant is
found in most tropical and subtropical countries. Growing in swampy areas,
including parts of India, Pakistan, Sri Lanka, Madagascar, and South Africa,
Indonesia, South pacific and Eastern Europe. About 20 species related to CA
grow in most parts of the tropic or wet pantropical areas such as rice paddies,
and also in rocky, higher elevations. It is a tasteless, odourless plant that
thrives in and around water.
Pennywort has small fan-shaped green leaves with white or
light purple-to-pink or white flowers and it bears small oval fruit . The whole
plant is used for medicinal purposes. It is widely used as a blood purifier as
well as for treating high blood pressure, for memory enhancement and promoting
longevity. In Ayurveda, CA is one of the main herbs for revitalizing the nerves
and brain cells. Eastern healers relied on CA to treat emotional disorders,
such as depression, that were thought to be rooted in physical problems. In the
Western medicine, during the middle of the twentieth century, CA and its
alcohol extracts reported to have shown positive results in the treatment of
leprosy.
Active Compound
The primary active constituents of CA are saponins (also
called triterpenoids), which include asiaticosides, in which a trisaccharide
moiety is linked to the aglycone asiatic acid, madecassoside and madasiatic
acid. These triterpene saponins and their sapogenins are mainly responsible for
the wound healing and vascular effects by inhibiting the production of collagen
at the wound site. Other components isolated from CA, such as brahmoside and
brahminoside, may be responsible for CNS and uterorelaxant actions, but are yet
to be confirmed by clinical studies. Centelloside and its derivatives are found
to be effective in the treatment of venous hypertension.
Efficacy of Pennywort
Venous insufficiency
CA might assist in the maintenance of connective tissue. In
the treatment of scleroderma, it might also assist in stabilizing connective
tissue growth, reducing its formation as it reportedly stimulated the formation
of hyaluronidase and chondroitin sulfate, as well as exerted a balancing effect
on the connective tissue. CA was reported to act on the connective tissues of
the vascular wall, being effective in hypertensive microangiopathy and venous
insufficiency and decreasing capillary filtration rate by improving
microcirculatory parameters.
Sedative and anxiolytic properties
CA was described to possess CNS effects in Indian literature
such as stimulatory-nervine tonic, rejuvenant, sedative, tranquilizer and
intelligence promoting property. Pennywort has been traditionally used as a
sedative agent in many Eastern cultures; the effect was postulated mainly due
to the brahmoside and brahminoside constituents, while the anxiolytic activity
is considered to be, in part due to binding to cholecystokinin receptors.
Antidepressant
The antidepressant effects of total triterpenes from CA on
the immobility time in forced swimming mice and concentration of amino acid in
mice brain tissue was observed. In the study, imipramine and total triterpenes
from CA reduced the immobility time and ameliorated the imbalance of amino acid
levels confirming the antidepressant activity of CA.
Antiepileptic
Asian CA traditionally used as anxiolytic and
anticonvulsant. The isolated steroids from the plant have been used to treat
leprosy. A research suggested the potential of aqueous Pennywort extract as
adjuvant to antiepileptic drugs with an added advantage of preventing cognitive
impairment. Various experimental models found Pennywort show protective action
against increase in intracranial electric stimulation (ICES) and
chemo-convulsions. It also showed a reduction in formation of lipid
peroxidation products, reduction in spontaneous motor activity, potentiation in
diazepam withdrawal-induced hyperactivity, hypothermia, and potentiation of
pentobarbitone sleeping time.
Cognitive and antioxidant
CA is known to re-vitalize the brain and nervous system,
increase attention span and concentration and combat aging. A study
demonstrated cognitive-enhancing and anti-oxidant properties of CA in normal
rats. A research suggested the potential efficacy of CA in preventing the
cognitive deficits, as well as the oxidative stress. In one study, derivatives
of asiatic acid derivatives were shown to exert significant neuroprotective
effects on cultured cortical cells by their potentiation of the cellular
oxidative defence mechanism. Therefore, these agents were proved to be
efficacious in protecting neurons from the oxidative damage caused by exposure
to excess glutamate.
Gastric ulcer
A laboratory study was reported in which aqueous extract of
CA was found to be effective in inhibiting gastric lesions induced by ethanol
administration. The authors concluded that the CA extract presumably
strengthened the gastric mucosal barrier and reduced the damaging effects of
free radicals. Both the drugs and the herb extract showed a dose-dependent
reduction of gastric ulceration, which, except for the antiulcer effect of
famotidine, could be reversed with bicucullin methiodide. One study showed that
CA and its constituents, asiaticosides have an anti-inflammatory property that
was brought about by inhibition of nitric oxide (NO) and thus facilitating
ulcer healing. Some other researchers also showed the efficacy of CA through
preclinical and clinical studies for healing gastric ulcers. CA has also been
investigated to demonstrate its role in periodontal therapy.
Antinociceptive and antiinflammatory
The aqueous CAE revealed significant antinociceptive
activity with both the models similar to aspirin but less potent than morphine
and significant antiinflammatory activity comparable to mefenamic acid. These
results suggested that the aqueous CA extracts possesses antinociceptive and
antiinflammatory activities which justified the traditional use of this plant
in the treatment of inflammatory conditions or rheumatism.
Radioprotection
Previous studies have suggested that CA could be useful in
preventing radiation-induced behavioural changes during clinical radiotherapy.
The plant extracts were also tested for its radioprotective properties at a
sublethal dose (8 Gy) of Co 60 gamma radiation. A 100 mg/kg dose increased the
survival time of the mice significantly. Body weight loss of the animals in the
drug treated group was significantly less in comparison with the animals that
were given radiation only.
Wound healing
The CA extracts (CAE) have been used traditionally for wound
healing and the research has been increasingly supportive for these claims. A
preclinical study reported that various formulations (ointment, cream, and gel)
of an aqueous CAE applied to open wounds in rats (3 times daily for 24 days)
resulted in increased cellular proliferation and collagen synthesis at the
wound site, as shown by an increase in collagen content and tensile strength.
The authors found that the CAE-treated wounds epithelialized faster and the
rate of wound contraction was higher when compared to the untreated control
wounds. In one laboratory animal study, the authors concluded that
asiaticosides may have enhanced the induction of antioxidants at an initial
stage of wound healing, but continued application of the preparation seemed not
to increase the antioxidant levels in wound healing.
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Source: Pharmacological Review on Centella asiatica: A Potential Herbal Cure-all.”. Indian J Pharm Sci: 546–56. September 2010.
Source: Pharmacological Review on Centella asiatica: A Potential Herbal Cure-all.”. Indian J Pharm Sci: 546–56. September 2010.
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