Preliminary Phytochemical Screening
The chemical evaluation includes qualitative chemical tests which have been used for identification of various phytoconstituents present in the powdered crude drug. The Preliminary phytochemical investigations of aqueous extract, acetone extract, ethanolic extract, chloroform extract and methanolic extract of Curcuma longa rhizome using commonly employed precipitation and coloration reactions were performed by various researchers which reveals the presence such as carbohydrates, proteins, alkaloids, glycosides, terpenes, steroids, flavonoids, tannins and saponins [1, 8, 9]. The corresponding tests performed by various researchers were being compiled from standard published literatures which are described below.
Preparation of the Extract
The rhizomes of Curcuma longa were collected and sun dried, cut into small pieces The small piece of dried rhizome was then grinded to get a fine powder, which is ready for use [8, 9].
Test for Alkaloid
The extract was mixed with 3 ml of dilute hydrochloric acid and then filtered thoroughly. The filtrate was tested carefully with following test [9]:
Mayer's Test:To a 1 ml or 2 ml of filtrate, few drops of Mayer’s reagent are added by the side of the test tube. The white or creamy precipitate indicated test as positive (presence of alkaloids) [1, 5, 8, 10]. Wagner Test: :1 ml or 2 ml of the filtrate extract was treated with Wagner’s reagent; formation of brown reddish precipitate shows positive result of alkaloids [1, 5, 8]. Dragendroff’s Test: :To a few ml of filtrate, 1–2 ml of Dragendorff’s reagent was added formation of prominent yellow precipitate indicates the presence of alkaloids [5, 8].
Test for Glycosides
To 2 ml test solution, added with equal quantity of Fehling's solution A and B and solution was heated gives the positive result of glycoside. A brick red precipitate was observed [8]. Legal's Test: To 2 ml or 1 ml test solution, pyridine and alkaline sodium nitroprusside was added ,get a blood red or pink colour indicate presence of glycoside [1, 8, 9]. Keller-Killani Test: To 2 ml glacial acetic acid containing a drop of FeCl3 treated with extract .Formation of a brown colour ring indicates the presence of glycoside [1, 9]. Borntrager’s Test: Firstly extract was boiled with dilute sulphuric acid, filtered and to the filtrate chloroform was added and shaken well. The organic layer was separated to which ammonia is added slowly. It also shows positive result, by pink to red colour in the ammonical layer [5].
Test for Flavonoids
Shinoda Test:2 ml test solution added with few fragments of Magnesium ribbon, dropwise conc. H2SO4 was added. The results shows pink scarlet or crimson red colour [1, 8]. Alkaline Reagent Test:The test solution, was treated with sodium hydroxide solution, which gives a yellow or red colour [1, 8]. Zn Test 2 ml extract were mixed with Zn dust and conc. HCl, after a few minutes red colour observed and it means presence of flavonoid [1, 8].
Test for Tannins
Ferric Chloride Test:The extract solution mixed with drops of ferric chloride solution. Presence of gallic tannins, blue colour was observed and green black for catecholic tannins [1, 5, 8]. Gelatin Test: A white precipitate is obtained by mixing of 2 ml test solution and 1% Gelatin solution containing 10% sodium chloride [8].
Test for Saponins
Test for Triterpenoids
Test for Phenol
Test for Fats and Fixed Oils
Stain Test: Between the two filter papers small amount of the extract was pressed, the stain on the filter paper indicates the presence of fixed oils [8]. Saponification Test: Small quantity to the extract solution with a drop of phenolphthalein was treated with few drops of 0.5 N alcoholic potassium hydroxide and heated on a water bath for 1–2 h. The results shows formation of soap or partial neutralization for the alkali indicates the presence of fats and fixed oils [8].
Test for proteins and amino acids
Millon's Test: : 2 ml test solution is added with Millon's reagent gives a white precipitate, which on heating changes to red [1, 5, 8, 10]. Ninhydrin Test: To 2 ml test solution, ninhydrin solution was treated and then boiled. Formation of blue colour indicates the presence of amino acid. Again 2ml test solution, 0.2% ninhydrin solution was treated with amino acids and proteins, then boiled shows a violet colour [1, 8].
Test for Carbohydrates
The extract was dissolved in 5–10 ml of distilled water and filtered through Whatmann No.1 filter paper and the filtrate is used for the following test of carbohydrates.
Molish Test:Firstly 2 ml solution was placed in a test tube then 1 drop of Molish Reagent was added. 2 ml of conc. HCl was added from the sides of the test tube. A violet ring was observed in the test tube. Formation of a violet ring at the junction of the two liquids indicates presence of carbohydrates [5, 9]. Fehling Test: : Dilute HCl was hydrolysed with 2 ml of extract and extract also neutralized with alkali and heated with Fehling’s solution A and B, formation of red precipitate it indicates the presence of reducing sugar [1, 9]. Benedict’s Test:The filtrate were treated with Benedict’s reagent and heated gently, appearance of orange red precipitate indicates the presence of reducing sugar [1]. Iodine Test: 5 drops of Iodine solution were treated with 2 ml of extract, gives blue colour indicates the positive test [9].
Phytopharmacology
Turmeric has several therapeutic and pharmacologic activities. The following is the most important phytopharmacology and therapeutic properties of turmeric.
Anti-inflammatory
Curcuma longa exhibit potent antiinflammatory effects due to volatile oils and curcumin. One half of curcumin if taken as oral is effective for Chronic inflammation, was found to be as helpful as cortisone or phenylbutazone in instances of acute inflammation [11]. Turmeric is credited with hot potency and anti-inflammatory action with specific lipoxygenase- and COX-2-inhibiting properties. Rheumatic complaints are often connected with inflammatory changes of joints It cures the etiological factors and pathological changes of inflammation [6, 12].
Curcuminoids have a properties that inhibit LOX, COX, phospholipases, leukotrienes, prostaglandins, thromboxane, nitric oxide elastase, hyaluronidase, collagenase, monocyte chemoattractant protein-1, interferon inducible protein, TNF and interleukin-12 [5]. In an animal model ,in case mice application of curcumin at doses between 50 and 200 mg/kg has inhibited oedema. Curcumin can reduce 50% in oedema when it applied with a dose of 48 mg/kg body weight. It is same effective as cortisone and phenylbutazone at similar doses. Again in rats, when applied a lower dose of 20–80 mg/kg decreased paw inflammation and oedema. Curcumin with a dose of 40 mg/kg can inhibited formaldehyde induced arthritis in rats and demonstrated no acute toxicity at doses up to 2 g/kg/day. In an animal study, it shows rheumatoid arthritis induced by streptococcal cell wall, intraperitoneal injection of turmeric extract containing 4 mg total curcuminoids/kg/day for four days prior to induction of arthritis, inhibited joint inflammation in both acute (75%) and chronic (68%) phases [4, 13].
Antimicrobial Properties
The growth of a variety of bacteria, parasites, and pathogenic fungi are reduced due to turmeric extract and the essential oil of Curcuma longa. A study of chicks which is infected with the caecal parasite. Eimera maxima proved that diets supplemented with turmeric helps in a reduction in small intestinal lesion scores and improved weight gain. Another study show that topically applied turmeric oil, inhibited dermatophytes and pathogenic fungi when guinea pigs were infected with either dermatophytes, pathogenic molds, or yeast. The lesions disappeared at seven days post-turmeric application was observed in the dermatophyte- and fungiinfected guinea pigs. It has been observed while using Curcumin to have moderate activity against Plasmodium falciparum and Leishmania major organisms [4, 14, 13].
Antidiabetic Properties
The experimental study has proved that turmeric have significant role in diabetes. It has been observed that a hexane extract (containing ar-turmerone), ethanolic extract (containing ar-turmerone, curcumin, demethoxycurcumin and bisdemethoxycurcumin) and ethanolic extract from the residue of the hexane extraction (containing curcumin, demethoxycurcumin and bisdemethoxycurcumin) are dosedependent stimulation of adipocyte differentiation. The result shows that the extract of turmeric ethanolic is the composition of curcuminoids and sesquiterpenoids is more strongly hypoglycemic than either curcuminoids or sesquiterpenoids. The effects of turmeric on postprandial plasma glucose and insulin are remarkable. It was observed that the ingestion of 6 g Curcuma longa had no significant effect on the glucose response [15–20]. Insulin changes extensively higher 30 min and 60 min after the OGTT including Curcuma longa. It is also been observed that AUC of insulin increases significantly after the ingestion of Curcuma. longa and OGTT [5]. Turmeric also decreases complications in diabetes mellitus. Experimental study on albino rats shows the effectiveness of turmeric on blood sugar and polyol pathway found that both turmeric and curcumin decreased blood sugar level in alloxan-induced diabetes [12].
Antioxidant Effects
Water and fat soluble extracts of turmeric and its curcumin component possess strong antioxidant activity, when it is comparable to vitamins C and E. Curcumin pre-treatment has effective result which decreases ischemiainduced changes in the heart. An in vitro study was conducted utilizing bovine aortic endothelial cells for measuring the effect of curcumin on endothelial hemeoxygenase-1, an inducible stress protein. This study also enhanced cellular resistance to oxidative damage, when curcumin incubated for 18 h. It can protect lipids or hemoglobin from oxidation. Curcumin have antioxidants properties so it can significantly inhibit the generation of reactive oxygen species (ROS) such as H2O2, superoxide anions and nitrite radical generation by activated macrophages. Its derivatives. can prevent and treating cholelithiasis, as derivatives (bisdemethoxycurcumin and demethoxycurcumin) also have antioxidant activities [4, 11, 13].
Hepatoprotective Effects
Turmeric demonstrated both hepatoprotective and reno-protective characteristic similar to silymarin mainly due to its antioxidant properties, as well as its ability to decrease the formation of pro-inflammatory cytokines (3–5). Animal studies have revealed that turmeric’s hepatoprotective effects from a variety of hepatotoxic insults, including carbon tetrachloride (𝐶𝐶𝑙4), galactosamine, acetaminophen (paracetamol), and Aspergillus aflatoxin. It is noticed that in rats with 𝐶𝐶𝑙4induced acute and subacute liver injury ,administration of curcumin drastically decreased liver injury in test animals compared to controls. Extract of turmeric is very effective which inhibit production of fungal aflatoxin by 90% when tested on ducklings infected with Aspergillus parasiticus preventing and treating cholelithiasis possible due to sodium curcuminate, a salt of curcumin, also exerts choleretic effects by increasing biliary excretion of bile salts, cholesterol, and bilirubin, as well as increasing bile solubility [4, 11].
Anti-Cancer Effect
Numerous animal studies involving rats and mice, as well as in vitro studies utilizing human cell lines have been done on turmeric that influence on the carcinogenesis. Several in vitro studies have reported that curcumin is able to control carcinogenesis at three stages: angiogenesis, tumour promotion, and tumour growth. Curcumin exerts inhibition of cell proliferation and tumour growth, noted by two studies of colon and prostate cancer. The activity of several common mutagens and carcinogens are also suppressed by turmeric and curcumin. Turmeric and curcumin have anti-carcinogenic effects have been related to direct antioxidant and free-radical scavenging effects, as well as their ability to indirectly increase glutathione levels, thereby aiding in hepatic detoxification of mutagens and carcinogens, and inhibiting nitrosamine formation Curcumin has also been shown to inhibit the mutagenic induction effect of UV rays [11, 13].
It has been observed in Swiss mice that the dietary turmeric could be well used as a chemopreventive agent in benzo-(alpha)pyrene-induced for stomach tumours. It is reported that to produce notable symptomatic relief in patients with external cancerous lesions when an ethanolic extract of turmeric, as well as an ointment containing curcumin is applied. Turmeric demonstrate that it neutralize carcinogenic free radicals due to its antioxidants property. Acetyl curcumin was found inactive. Many reports showed that turmeric inhibited tumour necrosis factor (TNF)-α-induced expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and Eselectin by human umbilical vein endothelial cells as well act as a antitumor agents to be helpful in inducing apoptosis or programmed cell death (PCD) in human myeloid leukaemia cells (HL—60). It is evident from the test that the Curcumin-I, II, and III from turmeric have the properties of cytotoxicity, antioxidant and anti-inflammatory. Extensive research reveals that these compounds possess strong inherent property against leukaemia and colon, central nervous system (CNS), melanoma, renal, and breast cancer cell lines [12].
Cardiovascular Effects
Due to antioxidant property of turmeric which generates a protective effect on the cardiovascular system include lowering cholesterol and triglyceride levels, decreasing susceptibility of low density lipoprotein (LDL) to lipid peroxidation, and inhibiting platelet aggregation. A study reports that turmeric extract being given to 18 atherosclerotic rabbits with low-dose (1.6–3.2 mg/kg body weight daily) shows decreasing susceptibility of LDL to lipid peroxidation, in addition to that it lowers the plasma cholesterol and triglyceride levels. The higher dose decreases cholesterol and triglyceride level but it did not decrease lipid peroxidation of LDL. Turmeric extract’s has its potential effect on cholesterol levels may possible be due to decreased cholesterol uptake in the intestines and increased conversion of cholesterol to bile acids in the liver. It was also observed that C. longa inhibits platelet aggregation to be via potentiation of prostacyclin synthesis and inhibition of thromboxane synthesis [4, 11, 13].
Cardiovascular Effects
The constituents of Curcuma longa namely Sodium curcuminate and p-tolymethylcarbinol have several protective effects on the gastrointestinal tract. Sodium curcuminate exhibits the characteristics of inhibition of intestinal spasm and p-tolymethylcarbinol, increases gastrin, secretin, bicarbonate, and pancreatic enzyme secretion. Turmeric has also been seen that it can inhibit ulcer formation caused by stress, alcohol, indomethacin, pyloric ligation, and reserpine, considerably increasing gastric wall mucus in rats applied to these gastrointestinal insults [11]. A study performed with an open, phase II trial given on 25 patients with endoscopicallydiagnosed gastric ulcer, where 600 mg powdered turmeric given five times daily, showed completely healed in 48% of patients. The results show no adverse reactions or blood abnormalities. It was noted that curcumin reduced mucosal injury in mice with experimentally induced colitis. In rat models of experimentally-induced pancreatitis, curcumin was able to decrease inflammation. In other type of induced pancreatitis such as cerulean or ethanol, curcumin was also able to inhibit the inflammatory mediators as measured by histology, pancreatic trypsin, serum amylase, and neutrophil infiltration [13].
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