Evaluation of phytochemicals in some indigenous aromatic medicinal plants of North-East India

 

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ABOUT AUHTOR
*R SHARMA, S SARMA
Assam Down Town University, Guwahati, Assam, India
*Rupsmita2010@gmail.com

 

ABSTRACT
Objectives: The aim of the present study was to estimate flavonoid and phenolic content, and to evaluate invitro antioxidant activity of an aqueous extract of Alpinia nigra and Allium tuberosum.
Methods: The air dried stem of A. nigra and leaves of A. tuberosum was ground to powder and extracted with water and 95% of ethanol. The extract was screened for phytochemicals, total phenolic content (TPC) and total flavonoid content (TFC) with its potential antioxidant activities using hydrogen peroxide-scavenging assay.
Results: Phytochemical test shows that extract contains variety of phytochemicals among which there is a high level of total phenol and flavonoids. The total phenolic content (TPC) of A. nigra and A. tuberosum was 0.450±0.0740 and 1.663±0.296; respectively. The total flavonoid content (TFC) of A. nigra and A. tuberosum was 0.322±0.077 and 0.978±0.119, respectively. The plants possessed potent antioxidant activity when compared with the reference compound ascorbic acid (vitamin C).
Conclusions: A. nigra and A. tuberosum may be useful for the preparation of neutraceuticals as potent antioxidant to treat various human diseases and their complications.

REFERENCE ID: PHARMATUTOR-ART-2478

PharmaTutor (ISSN: 2347 - 7881)

Volume 5, Issue 3

Received On: 04/11/2016; Accepted On: 06/12/2016; Published On: 01/03/2017

How to cite this article: Sharma R, Sarma S;Evaluation of phytochemicals in some indigenous aromatic medicinal plants of North-East India; PharmaTutor; 2017; 5(3); 42-47

 

INTRODUCTION
North east India comprises seven states commonly known as the “Seven Sisters”. These include Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, and Tripura. It is well known for its biodiversity which comprises of various types of flora and fauna.[1] There are over 166 separate tribes. Over generations, these tribes have been using various medicinal plants found in the hill states as home remedies for several types of diseases. Plants containing phytochemicals such as flavonoids and tannins are believed to possess anti-oxidant and anti-inflammatory activities.[2]

Alpinia nigra (Burtt), belonging to the family Zingiberaceae, is widely grown in India, Bangladesh, China and Srilanka. It is also referred to as Jongly Ada, Tara, Galangal, False galangal, Greater galangal, Black-Fruited, or Kala. It is a perennial, rhizomatous aromatic medicinal plant. A. nigra has two flavone glycosides, astragalin and kaempferol-3-O-glucuronide. These two glycosidesare believed to have antibacterial, antioxidant, antiprotozoal, hepatoprotective, and glycation inhibitory effects.[3]

 

Allium tuberosum belonging to the family Amaryllidaceae is a perennial herb related to onion and mostly grown in China and Thailand for its culinary uses. It is commonly known as garlic chieves, Chinese chieves, or oriental chieves. Essential oil obtained from A. tuberosum has larvicidal activity against larvae of Aedes mosquitoes.[4]
 
The most important feature of A. tuberosum is considered to be the inhibition of reactive oxygen species (ROS). It is a potential source of several antioxidants and helps control the degenerative or pathological processes involved in aging, cancer, Alzheimer’s disease, and heart diseases.[5]

 
Plant derived antioxidant compounds act by preventing the generation of free radicals, and thereby alleviate the diseases caused by oxidative stress. However, various synthetic antioxidant agents have been developed to remediate oxidative stress, but factors such as, high cost, lack of availability and side effects remained as major setbacks in combating oxidative stress. Consequently, natural antioxidants received a prominence because they are less expensive, often free from side effects, and abundant in many plant sources.[6]

Therefore, in view of the medical significance, the present study was carried out to screen the phytochemical constituents, to estimate flavonoid and phenolic content, and to evaluate in-vitro antioxidant activity from aqueous extract of the plants, A. nigra and A. tuberosum.

Materials and Methods

Plant materials
A.nigra: Fresh plants free from diseases were collected during the month of January, 2014 from Nalbari district of Assam.
A. tuberosum: The leaves were collected from the market of Manipuri Basti, Guwahati. Taxonomic identification of the plants were carried out in Assam Agriculture University and compared with the herbarium present in the Department of Botany, Cotton College, Guwahati.
The plant materials were thoroughly washed under running water, cut into pieces; air dried for 7 days and pulverized into fine powder in a grinding machine and the resulting fine powder was kept in small plastic bags with paper labeling.                   

Preparation of water extract
The water extraction was carried out using classical method. The ground leaves material was weighed using an electronic balance and mixed with 100 mL of sterile water (Table 1). After that, the mixture was boiled at 50-60°C for 30 minutes using water bath and it was filtered through WhatmanGrade No.1 filter paper. Then filtrate was centrifuged at 2500 rpm for 15 minutes and filtrate was stored in sterile bottles at 5°C for further use.

Preparation of ethanol extract
Ground samples were extracted with I00 mL of 95% ethanol on water bath at 70°C for two hours (Table 1). The extracted samples were centrifuged at 2500 rpm and the supernatant was transferred into a 50 mL volumetric flask. The residue was further rinsed two more times, the extracts were pooled and the volume adjusted to 50 mL with 95% ethanol. The samples were stored at −4°C until analysis.

Table 1: Concentration of the plant extracts prepared

Weight (g)

Volume of water (mL) for the aqueous extracts

Strength of 100 mL ethanol used

1

100

95%

2

100

95%

3

100

95%

Qualitative analysis of phytochemicals
Preliminary screening for phytochemicals in aqueous and ethanolic extracts of A. nigra and A. tuberosum plant were done as per standard biochemical procedures as previously described in Arulpriya et al. [3] The phytochemical analysis was done to determine the presence of saponins,  steroids, terpenoids, tannins, glycosides, flavonoids, carbohydrates, amino acids, coumarins, anthocyanin and    leucoanthocyanins.

Determination of total phenolic content (TPC)
The amount of total phenols in the extracts was determined with the Folin-Ciocalteu reagent method.[7] Gallic acid was used as a standard and the total phenolics were expressed as mg/g gallic acid equivalents (GAE). 1mL of sample was mixed with 1.0 mL of Folin and Ciocalteu's phenol reagent. After 3 min, 1.0 mL of sodim carbonate (7 %) was added and made up to 10 mL by adding distilled water. The reaction was kept in the dark for 90 min, after which its absorbance was read at 725 nm. A calibration curve was constructed with different concentrations of gallic acid (0.01-0.1 mM) as standard. The samples were analyzed in triplicates. 

Determination of total flavonoid content (TFC)
Quercetin was used as standard and flavonoid contents were measured as quercetin equivalent. The total flavonoid content was estimated by the aluminium chloride (AlCl3) method. Approximately, 0.5 mL of each sample and 300 μL of sodium nitrite (NaNO2) at 1:20 weight/volume (w/v) were pipetted into a test tube. The contents were vortexed for 10 seconds and left at room temperature for five minutes. Then 300 μL of AlCl3 (1:10 w/v), 2 mL of 1M sodium hydroxide (NaOH) and 1.9 mL of distilled water were added into the mixture. After vortexing for 10 seconds, the absorbance for each sample was measured at 510 nm using UV-visible spectrophotometer. The samples were analyzed in triplicates.

Hydrogen peroxide scavenging assay  The ability of the extracts to scavenge hydrogen peroxide (H2O2) was determined according to the method of Nabavi.[8] A solution of H2O2(40mM) was prepared in phosphate buffer, pH 7.4. The concentration of H2O2 was determined by absorption at 230 nm using a spectrophotometer. 4 mL of plant extracts (0.5-3.0gm/mL) in distilled water were added to a H2O2 solution at 230 nm was determined after ten minutes against a blank solution containing phosphate buffer without H2O2. Ascorbic acid was used as the standard compound.

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