Centella: The famous wild vegetable of Asia


Centella (Centella asiatica): The famous wild vegetable of Asia

Wild vegetable: Centella asiatica

Centella asiatica juice used in Vietnam

Classification

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Centella asiatica
Hydrocotyle asiatica L.
Trisanthus cochinchinensis Lour.

The names

Classificational name: Centella asiatica (L.) Urban.
Common name: Centella.
Regional names:
-Hindi: Brahmi booti.
-Chinese: Luei gong gen meaning "chipped big bowl", literally "thunder god's root".
-Tamil: Vallaarai.
-Sri Lanka: Gotu kola 
-Filipino:Takip-kohol.
-Vietnamese: Rau má (mother vegetable).
-Philippinean: Yahong yahong.
-In India, it is popularly known by a variety of names: bemgsag, brahma manduki, brahmanduki, brahmi, ondelaga or ekpanni (south India, west India), sarswathi aku (Andhra Pradesh), gotu kola, khulakhudi, mandukparni, mandookaparni, or thankuni (Bengal), depending on region. 

Distribution

Centella asiatica, commonly centella is a small, herbaceous, annual plant of the family Mackinlayaceae or subfamily Mackinlayoideae of family Apiaceae, and is native to India, Sri Lanka, northern Australia, Indonesia, Iran, Malaysia, Melanesia, Papua New Guinea, Vietnam and other parts of Asia. It is used as a famous wild vegetable and as a medicinal herb in Ayurvedic medicine, traditional African medicine, and traditional Chinese medicine. Botanical synonyms include Hydrocotyle asiatica L. and Trisanthus cochinchinensis (Lour.).

Description

The stems are slender, creeping stolons, green to reddish-green in color, connecting plants to each other. It has long-stalked, green, reniform leaves with rounded apices which have smooth texture with palmately netted veins. The leaves are borne on pericladial petioles, around 2 cm. The rootstock consists of rhizomes, growing vertically down. They are creamish in color and covered with root hairs.
The flowers are pinkish to red in color, born in small, rounded bunches (umbels) near the surface of the soil. Each flower is partly enclosed in two green bracts. The hermaphrodite flowers are minute in size (less than 3 mm), with 5-6 corolla lobes per flower. Each flower bears five stamens and two styles. The fruit are densely reticulate, distinguishing it from species of Hydrocotyle which have smooth, ribbed or warty fruit.
The crop matures in three months, and the whole plant, including the roots, is harvested manually.

Habitat

Centella grows along ditches and in low, wet areas. In Indian and Southeast Asian centella, the plant frequently suffers from high levels of bacterial contamination, possibly from having been harvested from sewage ditches. Because the plant is aquatic, it is especially sensitive to pollutants in the water, which are easily incorporated into the plant.

Culinary use

Centella is used as a leafy green in Sri Lankan cuisine, where it is called gotu kola. In Sinhalese gotu is translated as "conical shape" and kola as "leaf". It is most often prepared as malluma , a traditional accompaniment to rice and curry, and goes especially well with vegetarian dishes, such as dhal, and jackfruit or pumpkin curry. It is considered quite nutritious. In addition to finely chopped gotu kola, malluma almost always contains grated coconut, and may also contain finely chopped green chilis, chili powder, turmeric powder and lime (or lemon) juice. A variation of the nutritious porridge known as kola kenda is also made with gotu kola by the Sinhalese people of Sri Lanka. Kola Kenda is made with very well-boiled red rice (with extra liquid), coconut milk and gotu kola, which is pureed. The porridge is accompanied with jaggery for sweetness. Centella leaves are also used in sweet "pennywort" drinks.
In Indonesia, the leaves are used for sambai oi peuga-ga, an Aceh type of salad, and is also mixed into asinan in Bogor.
In Vietnam and Thailand, this leaf is used for preparing a drink or can be eaten in raw form in salads or cold rolls. In Bangkok, vendors in the famous Jatujak Market sell it alongside coconut, roselle, crysanthemum, orange and other health drinks.
In Malay cuisine the leaves of this plant are used for ulam, a type of Malay salad.
It is one of the constituents of the Indian summer drink thandaayyee.

Medicinal effects

Centella is a mild adaptogen, is mildly antibacterial, antiviral, anti-inflammatory, antiulcerogenic, anxiolytic, nervine and vulnerary, and can act as a a cerebral tonic, a circulatory stimulant, and a diuretic.
Centella asiatica may be useful in the treatment of anxiety, and may be a promising anxiolytic agent in the future.
In Thailand, tisanes of the leaves are used as an afternoon stimulant. A decoction of juice from the leaves is thought to relieve hypertension. A poultice of the leaves is also used to treat open sores.
Richard Lucas claimed in a book published in 1966 (second edition in 1979) that a subspecies "Hydrocotyle asiatica minor" allegedly from Sri Lanka also called fo ti tieng, contained a longevity factor called 'youth Vitamin X' said to be 'a tonic for the brain and endocrine glands' and maintained that extracts of the plant help circulation and skin problems. However according to medicinal herbalist Michael Moore, it appears that there is no such subspecies and no Vitamin X is known to exist.
Several scientific reports have documented Centella asiatica's ability to aid wound healing which is responsible for its traditional use in leprosy. Upon treatment with Centella asiatica, maturation of the scar is stimulated by the production of type I collagen. The treatment also results in a marked decrease in inflammatory reaction and myofibroblast production.
The isolated steroids from the plant also have been used to treat leprosy. In addition, preliminary evidence suggests that it may have nootropic effects. Centella asiatica is used to revitalize the brain and nervous system, increase attention span and concentration, and combat aging. Centella asiatica also has antioxidant properties. It works for venous insufficiency. It is used in Thailand for opium detoxification.
Followers of Sri Sri Thakur Anukulchandra, commonly known as Satsangees, all over the world take one or two fresh leaves with plenty of water in the morning after morning rituals. This is prescribed by Sri Sri Thakur himself.
'Many reports show the medicinal properties of C. asiatica extract in a wide range of disease conditions, such as diabetic microangiopathy, edema, venous hypertension, and venous insufficiency. The role of C. asiatica extract in the treatment of memory enhancement and other neurodegenerative disorders is also well documented. The first report concerning the antitumor property of C. asiatica extract was on its growth inhibitory effects on the development of solid and ascites tumors, which lead to increased life span of tumor-bearing mice. The authors also suggested the extract directly impeded the DNA synthesis. "In our study, C. asiatica extract showed an obvious dose dependent inhibition of cell proliferation in breast cancer cells.

New pharmacology studies

-Constituents: The purported active components of gotu kola (Centella asiatica), accounting for 1-8% of the constituents, include asiatic acid, madecassic acid, asiaticoside, asiaticoside A, and asiaticoside B.The leaves of Centella asiatica have also been reported to contain 170mg calcium, 30mg phosphorous, 3.1mg iron, 414mg potassium, 6.58mg beta-carotene, 0.15mg thiamine, 0.14mg riboflavin, 1.2mg niacin, and 4mg asorbic acid.
-Alzheimer's disease effects: Asiaticoside derivatives, including asiatic acid and asiaticoside 6, were shown to reduce hydrogen peroxide-induced cell death, decrease free radical concentrations, and inhibit beta amyloid cell death in vitro, suggesting a possible role for gotu kola in the treatment and prevention of Alzheimer's disease and beta amyloid toxicity.
-Antioxidant effects: Asiaticoside derivatives, including asiatic acid and asiaticoside 6, were shown to reduce hydrogen peroxide-induced cell death, decrease free radical concentrations, and inhibit beta amyloid cell death in vitro, suggesting a possible role for gotu kola in the treatment and prevention of Alzheimer's disease and beta amyloid toxicity.
-Anti-gastric ulcer activity: In rats, extract of Centella asiatica significantly inhibited gastric ulceration induced by cold and resistant stress, similar to the inhibition caused by famotidine and sodium valproate.The titrated extract of Centella asiatica (TECA) has been shown to have protective and therapeutic effects on gastric mucosal damage in rats. Fresh juice of Centella asiatica given in doses of 200 or 600mg/kg twice daily for five days was shown to have protective activity against gastric ulcers induced by ethanol, aspirin, cold-restraint stress, and pyloric ligation.7 The higher dose resulted in significantly increased mucin secretion and mucous formation, while significantly decreasing cell shedding.
-Anti-inflammatory effects: In rats, Madecassol was shown to decrease the severity of radiation-induced dermatitis vs. control.
-Anti-fertility effects: Animal study shows a consistent reduction of fertility in female mice after the ingestion of isothankuniside and its derivative BK compound, both of which are isolated from Centella asiatica.
-Antimicrobial effects: An in vitro study of Centella asiatica powder found no activity against the acid-fastness or viability of M. tuberculosis, despite its use in the treatment of leprosy (M. leprae). A subsequent in vitro study found asiaticoside to have little microbicidal activity against M. tuberculosis or M. leprae; however, when incorporated into liposomal form, the microbicidal activity of asiaticoside was greatly increased. Centella asiatica extract and asiaticoside are active against herpes simplex virus in vitro.
-Antineoplastic effects: In vitro, partially purified fractions of Centella asiatica crude extract significantly inhibit proliferation of cancerous cells in a dose-dependent fashion, with no toxic effects to human lymphocytes. In mice, oral administration of both crude extract ofCentella asiatica and partially purified fractions of the crude extract slow the development of solid and ascites tumors, and increase the lifespan of mice, with possible action directly on DNA synthesis.
-Anxiolytic properties: Bradwejn et al. performed a double-blind, placebo controlled trial to study the effects of gotu kola on acoustic startle response (ASR), a validated instrument used to measure levels of anxiety. At 30 and 60 minutes after intervention, subjects who consumed 12g dose of gotu kola (from crude herb capsules, Nature's Way Canada, Ltd.) mixed in 300ml of grape juice experienced a significant decrease in their ASR, suggesting the possible ability of gotu kola to decrease anxiety. The small sample size and use of healthy (non-anxious) subjects limit the application of these data, but do suggest that gotu kola may possess anxiolytic properties. Although gotu kola has been studied for anxiety, the exact mechanism of action remains unclear.
-Cardiovascular effects: In an investigation of oral Centellase (TTFCA 60mg three times daily) to stabilize carotid plaques, it was reported that TTFCA regulated and modulated collagen production over the 12-month study period.
-Hepatic effects: A randomized controlled trial showed that a combination product (CognoBlend® containing Bacopa monneria, Gingko biloba, cat's claw, gotu kola, rosemary) may be an effective adjunct treatment for patients with liver cirrhosis, although a mechanism of synergistic action in this study is unclear.
-Hepatic effects (hepatotoxicity): Researchers have hypothesized that gotu kola may contain di- or triterpenic active principles, which can produce hepatic injury by promoting apoptosis and altering cell membranes.
-Neuroprotective effects: The effect of chloroform: methanolic (80:20) extract of Centella asiatica (CA; 100 and 200mg/kg), was evaluated on the course of free radical generation and excitotoxicity in monosodiumglutamate (MSG) treated female Sprague Dawley rats. The extract showed significant improvement in catalase, super oxide desmutase, and lipid peroxides levels in hippocampus and striatum regions. Glutathione level was not altered with CA treatment. Similar observation was made with dextromethorphan. The general behavior, locomotor activity, and CAl a region of the hippocampus was significantly protected by CA indicating neuroprotective effect of CA in MSG induced excitotoxic condition. Hence it can be concluded that CA protected MSG induced neurodegeneration attributed to its antioxidant and behavioural properties. The researchers concluded that this activity of Centella asiatica can be explored in epilepsy, stroke and other degenerative conditions in which the role of glutamate is known to play vital role in the pathogenesis.
-Vascular effects: A controlled study in 21 subjects with postphlebitic limbs or lymphedema reports that daily Centellase (TTFCA) causes a significant decrease in both the lymphatic/plasma protein concentration ratio and distal edema. The total triterpenic fraction ofCentella asiatica (TTFCA) has been noted to reduce ankle edema, foot swelling, and capillary filtration rate, as well as to improve microcirulatory parameters (including resting flux, venoarteriolar response, PO2, PCO2) in subjects with reported venous insufficiency of the lower extremities. HU300 (containing 17.5mg of total triterpenoids derived from Centella asiatica), two tablets twice daily, is reported to decrease venous distensibility index, reduce venous congestion, and reduce supine venous pressure after eight months in subjects with venous insufficiency, deep vein thrombosis, or perimalleolar leg ulcers.
-Wound/burn healing effects: Asiatic acid, madecassic acid, and asiaticoside have been shown to stimulate the in vitro synthesis of collagen, both alone and in combination.The titrated extract of Centella asiatica (TECA), asiatic acid, and asiaticoside were shown to increase remodeling of a wound collagen matrix after injection into an animal model, through the stimulation of both collagen and glycosaminoglycan synthesis. Asiaticoside isolated from Centella asiatica increased hydroxyproline content, tensile strength, and collagen content of wounds after topical administration in an animal model. Asiaticoside was found to promote angiogenesis in chick chorioallantoic membranes in vitro.The application of topical 0.2% asiaticoside twice daily for seven days to cutaneous wounds in rats led to increased wound levels of antioxidants (superoxide dismutase, catalase, glutathione peroxidase, vitamin E, and ascorbic acid) and decreased lipid peroxide levels. Increased cellular proliferation and collagen synthesis was observed at wound sites after treatment with topical or oral extract of Centella asiatica in rats. An animal study found that application of topical Centella asiatica extract three times daily for 24 days to open wounds resulted in increased collagen content and tensile strength. An in vitro study of the effects of total triterpenoid fraction of Centella asiatica (TTFCA) on human skin fibroblasts found the extract to have no significant effect on cell proliferation, total protein synthesis, or proteoglycan synthesis; however, a significant increase in the percentage of collagen and cell layer fibronectin was observed. Asiaticoside was found to cause a dose-related increase in tensile strength after intramuscular administration of asiaticoside.
-Madecassol, an asiaticoside containing compound, inhibited the biosynthesis of acid mucopolysaccharides and collagens in an animal granuloma model. Madecassol also inhibited the proliferation of human embryo fibroblasts in vitro.

Pharmacodynamics/Kinetics

-Absorption: An animal study found that madecassoside, asiaticoside, Asiatic acid, and madecassic acid have a bioavailability between 30 and 50%.
-Distribution: Bosse et al. reported that peak plasma levels are reached 2-4 hours after oral ingestion, intramuscular injection, or topical application of Madecassol, a gotu kola preparation. Grimaldi et al. also found no difference in time to peak plasma concentration with different dosages or single versus chronic dosing in a crossover study of the total triterpenic fraction of Centella asiatica (TTFCA). The area under the curve significantly increased in a dose-dependent fashion after single doses of either 30mg or 60mg TTFCA in humans.
After chronic treatment for seven days with either 30mg or 60mg TTFCA twice daily, it was observed that peak plasma concentrations, AUC0-24, and half-life were significantly higher than after single dose administration, possibly explained by the fact that asiaticoside is transformed into asiatic acid in vivo.
-Metabolism: A study in 12 healthy volunteers found that asiaticoside is converted to asiatic acid in vivo by hydrolytic cleavage of the sugar moiety.
-Elimination: Madecassol is predominantly eliminated in the feces within 24-76 hours after ingestion, injection, or application, with a small unspecified amount metabolized by the kidneys.
                                                                              Edited and posted by Hồ Đình Hải
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