Phytochemical and Biological Investigation of Medicinal Plants

Geetha, B (2010) Phytochemical and Biological Investigation of Medicinal Plants. Doctoral thesis, The Tamil Nadu Dr. M.G.R. Medical University, Chennai.


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The herbal medicines are the major remedy in traditional medicinal system and are being used in medicinal practice for thousands of years. These have made a great contribution in maintaining human health. The practice continues even today because of the biomedical benefits in many parts of the world. There is phenomenal increase in the demand for the herbal medicines especially for those which have been scientifically validated. The alarming rapid rate of species extension which we are currently witnessing due in part to habitat destruction, lends certain urgency to the quest for plant derived drugs. Natural product research continues to be an important part of the drug discovery process. The main advantage of natural products as a source of lead compounds is the tremendous molecular diversity found in nature. Hence, we were interested in carrying out natural products research. ◆ Most of the species of Strobilanthes flower only in long intervals, such as between six and twelve years and in some, even at longer intervals like 35 years. One of the plant best known species S. Kunthianus (Kurinji), flowers once in twelve years. Interesting results of gregarious flowering of Strobilanthes increases bees and its vicinity during the flowering period. Immense quantities of honey become available and the rockbees in common hill visit the plant. However, so far there is no biological studies have been carried out on this special plant. So far only Lupeol has been isolated from the whole plant. Hence in the present study, a detailed evaluation of phytochemical and biological studies such as antioxidant, anti-inflammatory, analgesic and hepatoprotective activities were carried out. ◆ The whole plant of S. kunthianus was collected from Thalaikuntha region, near Ootacamund, Nilgiris district, Tamilnadu, India. The plant was identified and authenticated at Botanical Survey of India, Coimbatore. ◆ Pharmacognostical evaluation was carried out in order to establish the identity and to standardize the plant. Morphological and microscopical characters of leaves, flowers, stem and root were studied. Physicochemical parameters like total ash, acid insoluble ash, water soluble ash and sulphated ash values and extractive values like alcohol soluble and water soluble were determined. ◆ The stem and root of S. kunthianus were successively extracted with petroleum ether, chloroform, ethyl acetate and methanol. The flowers, stem, leaves and root were also extracted with methanol to obtain crude extracts by using Soxhlet method. The leaves and flowers were also subjected for cold methanol maceration. All the fourteen extracts were concentrated to dryness under reduced pressure and controlled temperature and the yields were noted. Preliminary phytochemical analysis was carried out. Glycosides and phenolics were found in successive ethyl acetate and methanol stem and root extracts and all the crude methanol extracts. The total phenol content was estimated by Folin Ciocalteau method in all the fourteen extracts. The crude methanol flower extract was found to contain very high total phenol content among all the extracts. ◆ The successive petroleum ether root and stem extracts, chloroform stem extract, macerated and crude methanol flower extracts were subjected to column chromatography for the isolation of constituents. The macerated methanol leaves extract was subjected to solvent-solvent extraction method to isolate phytoconstituents. Nine compounds were isolated and their purity was confirmed by TLC using different solvent systems. Based on the spectral analysis such as IR, NMR and Mass spectral data, the compounds were characterized. The compounds isolated from the petroleum ether root extract were lupeol (GS 1) and betulin (GS 2). Lupeol (PES 1) was also isolated from petroleum ether stem extract. From chloroform stem extract, 3, 5-bis (dimethyl carbamoyl) methyl-4- (11-cyclo hexyl undecyl)- 4-heptyl-N1,N1,N7,N7 tetra methyl heptane diamide (SC 1) was isolated. The compounds -amyrin (GSMES 3) and 1, 4-amino-tetrahydro-2H-pyran-3, 5-diol (G 1) were isolated from macerated methanol flower extract. From crude methanol flower extract, compounds β-sitosterol (CMF 1), 2, 2-(2- hydroxyethyl)-3-methyl-4-[(E)-3, 4, 6-trimethyl undec-4-ethyl] cyclohexyl propionate (CMF 2) and flavone glycoside (CMF 5) were isolated. From macerated methanol leaves extract, the compound decahydro-1, 1, 4a, 8- tetramethyl phenanthren-2 (1H, 3H, 4b H)-one (ML 1) was isolated. Except lupeol, all the other eight compounds were isolated for the first time from the plant. ◆ During the last two decades, there has been a growing interest in studies that are concerned with prevention of uncontrolled oxidative process leading to various diseases in living system. Several studies have shown the role of oxidative stress in the causation and progression of various diseases including atherosclerosis, carcinogenesis, neurodegenerative diseases, radiation damage, aging and various other pathological effects. Hence, in the present study, all the successive extracts of stem and root and six methanol extracts were screened for in vitro antioxidant activity using seven different methods. ◆ Among the tested extracts, the ethyl acetate extracts of root and stem showed potent in vitro antioxidant activity, when compared to ascorbic acid in ABTS method. These extracts showed better activity than other successive extracts of root and stem. In case of methanol extracts, the crude extracts showed good antioxidant activity in ABTS, H2O2, and total antioxidant capacity methods. The crude methanol flower extract was found to be the most potent among the methanol extracts. ◆ Many natural products have served as anticancer agents in the treatment and also has lead compounds for further research. All the extracts were tested for their cytotoxic activity against Hep-2 and HeLa cell lines. But weak activity in the tested cell lines indicated their safety inactivity towards cancer cell lines. ◆ Free radical and reactive oxygen species are well known inducers of cellular and tissue pathogenesis leading to several human diseases such as cancer, inflammatory disorders, hepatitis, diabetes mellitus, as well as in aging process. Many plant species possessing antioxidant activities were served as protective agents against these diseases. The crude methanol extracts of flower, stem, root and leaves showed potent in vitro antioxidant activity. Hence, in the present study, crude methanol extracts were selected for in vivo anti-inflammatory and analgesic studies. In the acute toxicity studies, all the four crude methanol extracts were found to be non toxic and no mortality was observed up to 15 days when given as single oral dose of 2000 mg/kg bw with no gross necropsy findings. ◆ In vivo acute anti-inflammatory activity was done with carrageenan, formalin and histamine induced paw edema methods and analgesic activity by hot plate and tail immersion methods for all the crude extracs at two different dose levels. The crude methanol flower extract treatment showed the maximum activity in all the methods among the tested extracts. However, standard ibuprofen showed potent activity than the extracts. Based on these results, crude methanol flower extract was selected for sub chronic anti-inflammatory studies using cotton pellet method. The extract was found to be active indicating its potency. Hence, this extract was subjected for in vivo hepatoprotective and antioxidant activities. ◆ The crude methanol flower extract was tested against CCl4 induced liver injury in rats at 100, 150 and 200 mg/kg bw doses. The administration of CCl4 caused a significant increase in the levels of ASAT, ALAT, ALP, TGL, TC, CR, TB and TBARS and decrease in the levels of TP, Albumin, CAT and SOD in serum. A significant restoration of these values towards the normal was observed in all the doses of the extract treatment. Similar results were observed for CAT, SOD and TBARS in both liver and kidney tissues. These results indicated strong antioxidant and hepatoprotective nature of crude methanol flower extract. The histopathological examination of liver and kidney tissues also confirmed these activities. ◆ In conclusion, the present work provides the pharmacognostical and phytochemical evaluation profiles to identify the plant. From the extracts by column chromatographic studies, eight compounds were isolated for the first time from this plant. The in vitro antioxidant and cytotoxicity studies of the extracts were established by using several standard methods. The in vivo anti-inflammatory and analgesic activities were established for crude methanol extracts in different models. The antioxidant and hepatoprotective properties were established for crude methanol flower extract. Biochemical and histological evidences were used to prove the activities. Hence, the present study provides a proof for the strong chemotaxonomical relationship and similarity of the biological property with the other species of Strobilanthes. OBJECTIVES ACHIEVED: 1. Pharmacognostical evaluation profile to identify the plant S. kunthianus was established. 2. Eight phytoconstituents were isolated for the first time from this plant. 3. Potent extracts were selected from seven standard in vitro antioxidant activity methods and subjected to in vivo studies. 4. In vivo anti-inflammatory, analgesic, antioxidant and hepatoprotective activities of the crude methanol flower extract of S. kunthianus was proved.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: Phytochemical, Biological investigation, Medicinal plants.
Subjects: PHARMACY > Pharmaceutical Chemistry
Depositing User: Devi S
Date Deposited: 23 Jun 2017 12:08
Last Modified: 17 Sep 2022 09:56

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