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| Year : 2008 | Volume
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| Issue : 3 | Page : 162-163 |
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| Herbal indicators as a substituent to synthetic indicators |
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Vishwas C Bhagat1, Radheshyam D Patil1, PR Channekar1, SC Shetty1, Atul S Akarte2
1 Department of Pharmacy, Rajgad Dnyanpeeth's College of Pharmacy, Bhor, Pune-412 206, India
2 Department of Pharmacy, Appasaheb Birnale College of Pharmacy, Sangli, Maharashtra, India
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| Date of Submission | 19-Mar-2008 |
| Date of Acceptance | 12-May-2008 |
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 Abstract | | |
In acid - base titrations, indicators are used to show sharp color change at intervals of pH. Natural pigments in plants are highly colored substances and may show color changes with variation of pH.
An attempt has been made to investigate the indicator activity of methanolic extract of flower pigments and to replace synthetic indicators as they have certain disadvantages like chemical pollution, availability problems and high cost.
Methanolic extract of Rosa indica (L) from family Rosaceae and Hibiscus rosa-sinensis (L) from family Malvaceae gives sharp and intense color change as compared to phenolphthalein and methyl orange. Herbal indicators are evaluated by using strong acid - strong base, strong acid - weak base, weak acid - strong base, and weak acid - weak base. In all these titrations the extract was found to be very useful and accurate for indicating the equivalence point (neutralization point).
From photochemical investigation and qualitative chemical tests for Rosa indica and Hibiscus rosa-sinensis shows presence of anthocyanins; which are the pigmented flavonoids; which may be the reason for its activity as an indicator. Apart from the above advantages the isolation of pure compounds possessing indicator's properties help to know the mechanism by which they shows indicator's properties and new theories of indicators could be established. Keywords: End point, herbal indicator, methanolic extracts, titrations
How to cite this article:
Bhagat VC, Patil RD, Channekar P R, Shetty S C, Akarte AS. Herbal indicators as a substituent to synthetic indicators. Int J Green Pharm 2008;2:162-3 |
| Introduction | |  |
The use of Rosa indica belonging to family rosaceae [1] for various pharmacological activities is well known, and the presence of colored pigments and chemical constituents like flavonoids [2] are responsible for a thought about its use as an indicator in acid base titrations.
Rosa indica is a yearly flowering plant and easily available in India and also throughout the world in high quantity and present in almost every garden to enhance the beauty of gardens.
Presently available acid base indicators like phenolphthalein and methyl orange [3] are synthetic indicators, which produce chemical hazards, [4],[5] availability problems and their high cost.
The Hibiscus rosa-sinensis is belonging to family Malvaceae. [1] The intention behind this study is simply to bring in market the use of flower pigments and to increase the wealth of traditional Indian medicinal system which is mostly plant-based and to help farmers regarding cultivation, collection of plants as well as to industry regarding preparation of above indicators, which lead to financial support to both farmers as well as industry. Titrate and titrant with indicators showed sharp and intense color change at the equivalence point that is at neutralization. [6]
| Materials and Methods | | |
Plant Materials
Fresh flowers of Rosa indica and Hibiscus rosa-sinensis were collected from the Bhor region and the garden of R. D's. College Of Pharmacy Bhor, Pune (M. S.) and authenticated at the Dept. of Botany, A. T. College, Bhor.
Reagents
Analytical grade reagents like hydrochloric acid (HCl), sodium hydroxide (NaOH), acetic acid (CH 3 COOH), ammonia (NH 3 ) and phenolphthalein were procured from R. D's. College Of Pharmacy Bhor, Pune (M.S.). Reagents and volumetric solutions were prepared as per Indian pharmacopoeia (I. P. 1996).
Preparation of Extract
1) Rosa indica : 1 gm fresh petals of Rosa indica were macerated for 24h in 10 ml of methanol.
2) Hibiscus rosa-sinensis : 1 gm of fresh petals of Hibiscus rosa-sinensis was macerated for 24h in 10 ml of methanol.
Experimental Procedure
The petals of flower were cleaned by distilled water and cut into small pieces and macerated for 24h in 10 ml of methanol. The extract was preserved in tightly closed glass container and stored away from direct sunlight. The calibration of apparatus like burettes, pipettes, and other required instruments and standardization of acids and bases were done as per procedures given in Indian Pharmacopoeia (I. P. 1996).
10 ml of titrant with two drops of each indicator Rosa indica (R. I.) and Hibiscus rosa - sinensis (H. R.) was titrated against titrates and the color changes for the indicators are listed in the [Table 1] and [Table 2].
The results of screening for strong acid-strong base (HCl - NaOH), strong acid- weak base (HCl - CH3COOH), weak acid-strong base (CH3COOH - NaOH) and weak acid-weak base (CH 3 cooh0 - NH 3 ) are listed in [Table 3]. Each titration is carried out five times by using 1N strength of acid and alkali and results were recorded as mean ± SEM.
| Results and Discussion | | |
For all type of titrations equivalence point obtained by methanolic extract of Rosa indica and Hibiscus rosa-sinensis either exactly coincided or very closed with equivalence point obtained by standard indicator phenolphthalein. This represents the usefulness of alcoholic flower extract as an indicator in acid base titrations. Its use in strong acid-strong base titration was found to be more significant over standard indicator as it gives sharp color change at equivalence point.
It is observed that indicators acts reversibly and gives sharp color change in both directions. The results obtained showed that the routinely used indicators could be replaced successfully by flower extract as they are simple, accurate, and precise and can be prepared just before experiment.
The proposed herbal indicators can be used as a substitute to synthetic indicators.
| Acknowledgement | | |
Authors are thankful to Prof. R. V. Shete (Principal) Rajgad Dnynapeeth's College of Pharmacy, Bhor, for the necessary facilities. Also I would like to extend my sincere thanks to Anantrao Thopte College, Bhor.
| References | | |
| 1. | Flora of Maharashtra State, Dicotyledones. Volume - 1. In: Singh NP, Karthikeyan S, Laxminarasimhan P, Prasanna PV, editors. 836 and 340.  |
| 2. | Jackman RL, Smith JL. In natural food colorants. In: Hendry GA, Houghton JD, editors. Glasglow Scotland: Blackie and Son; 1996. p. 244-307. |
| 3. | VOGEL'S textbook of quantitative chemical analysis. 6th ed. In: Mendhan J, Denney RC, Barnes JD, Thomas MJ, editors. p. 10.29, 335-9. |
| 4. | NTP. Toxicology and Carcinogenesis Studies of Phenolphthalein (CAS No. 77- 09-8) in F344/N Rats and B6C3F1 Mice (Feed Studies). Technical Report Series No 465. NIH Publication No. 97-3390. Research Triangle Park, NC: National Toxicology Program; 1996. p. 354. |
| 5. | HSDB. 2001. Hazardous Substances Data Base. National Library of Medicine. Available from: http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen? HSDB. |
| 6. | VOGEL'S textbook of quantitative chemical analysis. 6 th ed. In: Mendhan J, Denney RC, Barnes JD, Thomas MJ, editors. p. 10.2:313. |
Correspondence Address:
Vishwas C Bhagat
Department of Pharmacy, Rajgad Dnyanpeeth's College of Pharmacy, Bhor, Pune - 412 206
India
  | 2 |
DOI: 10.4103/0973-8258.42735
[Table 1], [Table 2], [Table 3] |
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