Medicinal properties of Amla (Emblica officinalis)
Amla is a medium-sized deciduous tree with gray bark and reddish wood which successfully grows in variable agro-climatic and soil conditions. The tree grows to a height of 60 ft (18 m). The leaves are very fine and small, only 1/8 in (3 mm) wide and 1/2 to 3/4 in (1.25-2 cm) long The flowers are small, greenish-yellow and borne in compact clusters in the axils of the lower leaves. The fruits are round or oval, with smooth textured skin. There are ~6 to 8 pale visible lines, appearing as ridges. unripe fruits are light green turning yellow to red at maturity. The stone is tightly set in the center of the flesh and contains 6 small seeds.
Amla is highly nutritious and is one of the richest sources of vitamin-C, amino acids and minerals. It contains several chemical constituents like tannins, alkaloids and phenols. Among all hydrolysable tannins, Emblicanin A and B; gallic acid, ellagic acid are reported to possess biological activity. Almost all parts possess medicinal properties, particularly fruit, which has been used in Ayurveda as a powerful rasayana and in customary medicine in the treatment of diarrhoea, jaundice, inflammation and several other ailments. Amla fruit is widely used in the Indian system of medicine as alone or in combination with other plants and is used to treat common cold and fever, as diuretic, laxative, liver tonic, refrigerant, stomachic, restorative, anti-pyretic, hair tonic; to prevent ulcer and dyspepsia.
Amla is one of the most extensively studied plants. Reports suggest that it contains tannins, alkaloids and phenols. Fruits have 28% of the total tannins distributed in the whole plant. The fruit contains two hydrolysable tannins Emblicanin A and B, which have antioxidant properties; one on hydrolysis gives gallic acid, ellagic acid and glucose wherein the other gives ellagic acid and glucose respectively. The fruit also contains Phyllemblin. Activity directed fractionation revealed the presence of several phytochemicals like gallic acid, corilagin, furosin and geraniin. Flavonoids like quercetin, alkaloids like phyllantine and phyllantidine are found. Along with these, it primarily contains amino acids, carbohydrates and other compounds. Its fruit juice contains the highest concentration of vitamin-C (478.56mg/100mL). Vitamin C levels are more than those in oranges, tangerines and lemons.
In comparison with apple, the edible fruit tissue is rich with proteins 3-fold and ascorbic acid160-fold and contains considerably higher concentration of most minerals and amino acids. Glutamic acid, proline, aspartic acid, alanine, and lysine are 29.6%, 14.6%, 8.1%, 5.4%and 5.3% respectively of the total amino acids.
Pulpy portion of fruit, after drying found to contain: gallic acid 1.32%, tannin, gum13.75%; albumin 13.08%; crude cellulose17.08%; mineral matter 4.12% and moisture 3.83%. Amla fruit ash contains chromium2.5ppm, zinc-4 ppm and copper-3 ppm. Compounds isolated from amla fruit are gallic acid, ellagic acid, 1-Ogalloyl-beta-D-glucose, 3,6-di-O-galloyl-D-glucose, chebulinic acid, quercetin, chebulagic acid, corilagin, 1,6- di-O- galloyl beta-D-glucose, 3-Ethylgallic acid (3-ethoxy 4,5-dihydroxybenzoic acid) and isostrictinin. Amla fruitalso contains flavonoids, kaempferol-3-O-alpha L-(6”- methyl) rhamnopyranoside andkaempferol-3-O-alpha L (6”-ethyl) rhamnopyranoside.
Approximately 50% and 20% of deaths are caused by infectious diseases in tropic areas and America respectively. Chemical constituent obtained from medicinal plants are being in used to cure antimicrobial infection since over hundred years (Mahady, Huang, Doyle, & Locklear, 2008). The organic solvent (like CHCl3, CH3OH) extract of amla (E. officinalis) shows efficient result against few gram +ive and gram ive bacteria (Rahman, Akbor, Howlader, & Jabbar, 2009). On other hand Vijayalakshmi discussed anti-microbial nature of aqueous E. officinalis fruit pulp extract alongside gram ive bacteria and gram negative bacteria (Vijayalakshmi et al., 2007). However, in future the E. officinalis drugs will serve as low-cost and safe medicines due to its antimicrobial activity.
Antifungal property of E. officinalis was reported against Aspergillus (Satish et al., 2007). Fruit ethanol and acetone extracts showed moderate activity against Fusarium equiseti and Candida albicans where Grisofulvin was used as standard antibiotic (Hossain et al., 2012). Plant methanolic extract of E. officinalis did not show antifungal activity against phytopathogenic fungi Aspergillus niger F2723 (Bobbarala et al., 2009).
Antioxidant and free radical scavenging activity
Galic acid equivalent as total phenolic content from fruit and seed of E. officinalis has excellent antioxidant properties and play an important role as free radical scavengers required in the maintenance of ‚redox homeostasis‛ responsible for diverse degenerative diseases (Prakash et al., 2012). The methanolic seed extract of Emblica officinalis has promising free radical scavenging activity of 1,1, Diphenyl-2-picryl-hydrazil (DPPH) in a concentration dependant manner (Priya et al., 2012). Methanolic extract of fruit pulp also have antioxidant and free radical scavenging activity (Mehrotra et al., 2011; Liu et al., 2008a; Liu et al., 2008b, Hazra et al., 2010, Majumdar et al., 2010).
Methanolic extracts of dried leaves of Phyllanthus emblica was used for the comparative study of antibacterial and antioxidant activity and the research work was ended positively showing the extract has both these activities (Shivaji et al., 2010). In a separate research work, it is seen that the water extract of E. officinalis fruit prepared according to Thai Herbal Pharmacopoeia has a strong potential for free radical scavenging, ferric reducing as well as inhibiting ROS (reactive oxygen species) production (Charoenteeraboon et al., 2010).
Saponins which are important constituents of E. officinalis have insecticidal or cytotoxic properties to certain insects (Chaieb, 2010). Although saponins which had shown insecticidal activity was collected from natural sources other than E. officinalis. But as saponins are bioactive compounds found in E. officinalis too, it is obvious that E. officinalis might have insecticidal activity and further evaluation can be conducted to get more precise evaluation.
Larvicidal and mosquitocidal activity
In a mosquitocidal property evaluation test Murugan et al. (2012) observed larvicidal and pupicidal activities of methanol extract of E. officinalis against the malarial vector, Anopheles stephensi showing 98% mortality rate at 100 ppm. The ethanol and methanol extracts of E. officinalis also exerted 100% mortality (no hatchability) at 400 ppm and above (Murugan et al., 2012). Jeyasankar et al. (2012) reported that the larvicidal activity of Phyllanthus emblica ethyl acetate leaf extracts. The study concluded that the ethyl acetate extract of P. emblica exhibited the maximum larvicidal activity (99.6%) with LC50 (lethal Concentration brings out 50% mortality) value of 78.89 ppm against the larvae of Aedes aegypti (Jeyasankar et al., 2012).
Pemminati et al. (2010) has checked the antidepressant activity of aqueous extract of fruits of E. officinalis in inbred adult male Swiss Albino mice weighing 25-30g. The test was carried out by forced swim test (FST) and tail suspension test (TST). The result of this test showed the antidepressant activity of E. officinalis as comparable to the of standard antidepressant drug imipramine.
Reports suggest that triphala can stimulate the neutrophil functions in the immunized albino rats (Srikumar et al., 2005). There was considerable dose dependent raise in haemagglutination antibody titre, macrophage migration index, hypersensitivity reaction, respiratory burst activity of the peritoneal macrophages, total leukocyte count, percentage lymphocyte distribution, serum globulin and relative lymphoid organ weight in Emblica treated albino mice indicating its ability to stimulate humoral and cell mediated immunity along with macrophage phagocyte (Suja et al., 2009).
E. officinalis showed anti-inflammatory activities in carrageenan induced acute and cotton pellet induced chronic inflammation in Sprague-Dawley rats by reducing paw volume in acute inflammation and by decreasing cotton pellet induced granulomas tissue lipid peroxidation, the granulomatous tissue mass, myeloperoxidase activity and plasma extravasation in chronic inflammatory condition (Muthuraman et al., 2011). E. officinalis water extract has reported to have inhibitory effect on the synthesis and release of inflammatory mediators in rats (Jaijoy et al., 2010).
It has been reported that mice treated with Emblica officinalis extract before exposure to different doses of gamma radiation can reduce the severity of symptoms of radiation sickness and mortality (Singh et al., 2006). Similar delayed onset of mortality and reduction in the symptoms of radiation sickness in mice were seen in consecutively triphala treated mice before irradiation when compared with the non-drug treated irradiated controls (Jagetia et al., 2002).
Amla fruit have been reported to have significant antihyperlipidemic, hypolipidemic, and anti-atherogenic effect (Santoshkumar et al., 2013). Treatment with Emblica officinalis caused significant reduction of Total Cholesterol (TC), Low Density Lipoprotein (LDL), triglyceride (TG) and Very Low Density Lipoprotein (VLDL), and a significant increase in High Density Lipoprotein (HDL) levels in patients with type II hyperlipidemia. Both treatments from E. officinalis and simvastatin produced significant reduction in blood pressure; however, this beneficial effect was more marked in patients receiving E. officinalis (Gopa et al., 2012). Histopathological study of thoracic aorta of Emblica officinalis treated group has shown decrease in atherogenicity compared to untreated high cholesterol diet fed rats. The data demonstrated that Emblica officinalis formulation was associated with hypolipidemic effects on the experimentally induced hypercholesteremic rats (Kumar and Kalaivani, 2011). It is also seen that E. officinalis treated rat showed more hypoglycemic and hypolipidemic activity than Phyllanthus acidus treated diabetic rats (Modilal and Pitchai, 2011).
To evaluate the immunostimulatory and side effects of Triphala in a clinical phase I, all the volunteers took Triphala for two weeks (3 capsules per day). As complete physical examinations, routine laboratory analysis and immunological studies were performed before ingestion and after initial meeting for 4 consecutive weeks. The result revealed significant immunostimulatory effects on cytotoxic T cells (CD3−CD8+) and natural killer cells (CD16+CD56+). Both of them increased significantly when compared with those of the control samples. However, no significant change in cytokine secretion was detected. All volunteers were healthy and showed no adverse effects throughout the duration of the study (Phetkate et al., 2012). Flavonoids, a group of essential bioactive secondary metabolites of Emblica officinalis, were evaluated for antioxidant potential, cytotoxicity and intestinal absorption. The research concluded that flavonoids from E. officinalis and some other medicinal plants hold a good prospective as nutraceutical & chemotherapeutics agents because of their antioxidant potential, no cytotoxicity and good intestinal absorptive property (Sharma et al., 2010). But it is confirmed that the chloroform soluble fraction of the ripe fruits of Amlaki containing alkaloids have both antimicrobial and cytotoxic activity (Rahman et al., 2009).
Anti-diabetic and hypoglycemic activity
Herbal formulations prepared by extracts of Tinospora cordifolia, Trigonella foenum and Emblica officinalis were evaluated for hypoglycemic effects and Oral Glucose Tolerance Test (OGTT) in normal and Alloxan induced diabetic rats and significant, marginal and very less decrease in blood glucose level was observed when different herbal combinations were used (Deep et al., 2011).
The polyherbal combination of extracts E. officinalis (fruit), Momordica charantia (fruit) and Trigonella foenumgraecum (leaves and seeds) had shown synergistic activity, as the glucose levels were decreased more significantly by the combination of extracts compared to the individual extract when used separately in streptozotocin induced diabetic rats (Satyanarayana et al., 2010). The aqueous fruit extract of Phyllanthus emblica was evaluated on type-II diabetes, triglycerides (TG) and liver-specific enzyme, alanine transaminase (ALT). This study showed that in a dose of 200mg/kg body weight the aqueous fruit extract can significantly reduce the blood glucose level in alloxaninduced diabetic rats (Qureshi et al., 2009). Another study reports that Phyllanthus emblica treated rat showed more hypoglycemic and hypo lipidemic activity than Phyllanthus acidus treated diabetic rats when the effect of orally administered aqueous extracts (350 mg/kg body weight) of fruits of Phyllanthus emblica and Phyllanthus acidus on serum glucose, glycosylated hemoglobin, insulin, cholesterol, triglycerides, HDL-cholesterol, protein, urea and creatinine were examined in control and extracttreated diabetic rats (Modilal and Pitchai, 2011).
The histopathological study of liver cells of rats was examined by administering E. officinalis as a preventative agent to reduce paracetamol induced hepatotoxicity and it has been observed that fruit extract has the ability to rectify toxicity or hepatic damage (Malar and Bai, 2009). Another histological study was undertaken to demonstrate the protective effect of 50% hydroalcoholic extract of the fresh fruit of E. officinalis against chronic toxicity induced by carbon tetrachloride and thioacetamide in rats. From the liver sections of the tested rats, it was observed that E. officinalis reversed the abnormal histopathology by accelerating the regenerative activity and in a few cases, the hepatocytic injury was found negligible in E. officinalis treated group of rats (Mir et al., 2007).
Anti-cancer and anti-proliferative activity
E. officinalis exhibits its anticancer activities through inhibition of activator protein-1 and targets transcription of viral oncogenes responsible for development of cervical cancer thus demonstrating its potential efficacy for treatment of human papillomavirus-induced cervical cancers (Mahata et al., 2013).
An in vitro cytotoxicity was performed against five human cancer cell lines and the activity was done using 100µg/ml of the ethanolic whole plant extract of E. officinalis. Against lung (A-549) cell line plant extract showed 82% growth inhibition. In case of liver cell line (Hep-2), it showed no activity, whereas in colon 502713 cell line, the plant extract displayed maximum activity. In case of IMR-32 neuroblastima cell line and HT-29 liver human cancer line, the plant extract showed 97% and 98% activity, respectively (Verma et al., 2012). E. officinalis fruit extract at 50–100 μg/mL can significantly inhibit cell growth of six human cancer cell lines, A549 (lung), HepG2 (liver), HeLa (cervical), MDA-MB-231 (breast), SK-OV3 (ovarian) and SW620 (colorectal). (Ngamkitidechakul et al., 2010). HepG2 and A549 cells were treated with P. emblica and T. bellerica extracts alone or in combination with doxorubicin or cisplatin and effects on cell growth were determined using the sulforhodamine B (SRB) assay. Both the plant extracts demonstrated growth inhibitory activity against the two cancer cell lines tested (Pinmai et al., 2008). Studies also demonstrated that amla extracts are cytotoxic and restrain the in vitro proliferation of some tumor cell lines such as MK-1 (human gastric adenocarcinoma) and B16F10 (murine melanoma) (Zhang et al., 2004).
HIV-reverse transcriptase inhibitory activity
Inhibition of HIV-Reverse Transcriptase (HIV-RT) by P. emblica plant extract fractions was tested on Peripheral Blood Mononuclear Cells. From this test it was observed that aqueous fraction and n-hexane fraction have highest inhibition of recombinant HIV-RT (91% and 89%, respectively) at 1 mg/ml concentration. Chloroform fraction showed highest inhibition of HIV-RT at 0.5 mg/ml and carbon tetrachloride fraction at 0.12 mg/ml concentration. At 0.12 mg/ml and 0.5 concentrations 50% of the HIVRT activity is inhibited in n-hexane fraction and carbon tetrachloride fraction respectively (Estari et al., 2012).
Anti ulcerogenic activity
The ethanolic extract of E. officinalis has found highly effective in controlling growth of H. pylori in-vitro with minimum inhibitory control ranging from 0.91 to 1.87 µg/ µl. The result concluded that the plant ethanolic extract is well retained with total phenolics, reducing power, flavanoids and the antioxidant properties which make amla a proper remedial use against H. pylori infection and gastric ulcer (Mehrotra et al., 2011).
Antimutagenic and wound healing activity
An investigation on Swiss albino mice showed that 50% methanolic extract of Emblica fruit can protect mice against the chromosome damaging effects of the wellknown mutagen cyclophosphamide (Agrawal et al., 2012). Ascorbic acid and tannins of E. officinalis, namely emblicanin A and emblicanin B have strong antioxidant action and it is proposed that the addition of these antioxidants support the repair process of cells. Emblica increases cellular proliferation at the wound site, as supported by a raise in the action of extracellular signalregulated kinase 1/2, along with an increase in DNA, type III collagen, acid-soluble collagen, aldehyde content, shrinkage temperature and tensile strength (Sumitra et al., 2009).