Muthiah Gomathinayagam’s research while affiliated with Annamalai University and other places

Analysis of organic solvent extracts of Enicostemma littorale reveals the presence of total phenols, vitamin C and E and carbohydrates. The organic solvent extracts of E. littorale exhibited antibacterial activities.

To study the antimicrobial activity of Enicostemma littorale (E. littorale) using different solvents. Chloroform, methanol and acetone extracts of different parts of E. littorale (leaf, stem and root) were evaluated for antimicrobial activity using disc diffusion method against some gram-negative species such as Escherichia coli, Klebsiella pnemoniae, Pseudomonas aeruginosa, Salmonella typhi and gram-positive species Staphylococcus aureus, Bacillus cereus, Bacillus subtilis and two fugal species viz., Aspergillus fumigates and Aspergillus flavus. The chloroform extracts showed the highest antibacterial activity. Among leaf, stem and root extracts, the stem extracts showed maximum antibacterial activity. All of the used extracts had no significant antifungal activity against Aspergillus fumigates and Aspergillus flavus. The chloroform stem extract showed highest activity (about 20 mm inhibition zone) against Bacillus subtilis (at 500 mg/mL) followed by the methanolic stem extract which showed highest activity against the same organism. The lowest antibacterial activity was observed by the acetone leaf extract (about 8 mm inhibition zone) against Escherichia coli. The findings of the study indicate littorale could also be a new source for antibiotics discovery.

Medicinal plants are the source for wide variety of natural antioxidants. In the study reported here, we have conducted a comparative study between the different parts of the plant Enicostemma littorale. The amount of total phenols and antioxidant enzymes Glutathione-S-Transferase, Superoxide Dismutase, Catalase and Peroxidase activities were evaluated and also the non-enzymatic antioxidants ascorbic acid, - tocopherol and Glutathione activities were evaluated. The results showed that the antioxidant activities varied greatly among the different plant parts used in this study and some parts are rich in natural antioxidants especially the flowers of E. littorale. These results suggest that Enicostemma littorale have strong antioxidant potential. Further study is necessary for isolation and characterization of antioxidant agents, which can be used to treat various oxidative stress-related diseases.

Aim of the review paper is to give an enlightenment on potential phyto-constituents and pharmacology of Enicostemma littorale (Gentianaceae). Enicostemma littorale is a perennial herb found throughout the greater part of India. The plant is traditionally used in rheumatism, abdominal ulcers, hernia, swelling, itches and insect poisoning. Enicostemma littorale Blume is a plant with a number of antioxidative phytochemicals, which include alkaloids, catechins, saponins, sterols, triterpenoids, phenolic acids, flavonoids and xanthones. It also contains minerals like iron, potassium, sodium, calcium, magnesium, silica, phosphate, chloride, sulphate and carbonate. The review gives a bird's eye view mainly on the biological activities, some of the compounds isolated and their pharmacological actions.

In this study, 5 μM ABA and GA3 concentration were used to study the effect of these growth regulators on the andrographolide content and antioxidant potentials of Andrographis paniculata. The growth regulators were applied by means of foliar spray during morning hours. A significant enhancement in non-enzymatic antioxidant contents was observed in all sampling days in A.paniculata plants under ABA and GA3 treatments. Ascorbic acid and α-tocopherol content was increased significantly under the growth regulator treatments in leaves, stem and roots of A. paniculata. The activities of antioxidant enzymes such as ascorbate peroxidase, superoxide dismutase and catalase were increased by ABA and GA3 treatments in the leaves, stem and roots of A. paniculata plants. The HPLC analysis was used to quantify the andrographolide content in control and growth regulator treated plants. The growth regulators ABA and GA3 treated plants showed increased contents of andrographolide when compared to control.

Changes in the sucrose metabolism of Curcuma longa L. plants were studied under treatment with different triazole compounds viz., triadimefon (TDM) and propiconazole (PCZ). Plants were treated with TDM at 15 mg/L and PCZ at 10 mg/L separately by soil drenching on 80, 110, and 140 days after planting (DAP). The plants were harvested randomly on 90, 120, and 150 DAP to determine the effect of both the triazoles on sucrose metabolizing enzymes and phenol content. The sucrose metabolism was studied by analyzing sucrose metabolizing enzymes like sucrose synthase and sucrose phosphate synthase. All the analyses were assayed in leaves and tubers of both control and treated plants. It was found that both of the triazole compounds had profound effects on these parameters.

In this study, 5 μmol·L−1 abscisic acid (ABA) and gibberellic acid (GA3) were used to study the effect of both growth regulators on the morphological parameters and pigment composition of Andrographis paniculata. The growth regulators were applied by means of foliar spray during morning hours. ABA treatment inhibited the growth of the stem and internodal length when compared with control, whereas GA3 treatment increased the plant height and internodal length. The total number of leaves per plant decreased in the ABA-treated plants, but GA3 treatment increased the total number of leaves when compared with the control. Both growth regulators (ABA and GA3) showed increased leaf area. ABA and GA3 treatments slightly decreased the total root growth at all the stages of growth. The growth regulator treatments increased the whole plant fresh and dry weight at all stages of growth. ABA enhanced the fresh and dry weight to a larger extent when compared with GA3. An increase in the total chlorophyll content was recorded in ABA and GA3 treatments. The chlorophyll-a, chlorophyll-b, and carotenoids were increased by ABA and GA3 treatments when compared with the control plants. The xanthophylls and anthocyanin content were increased with ABA and GA3 treatments in A. paniculata plants.

The effect of different plant growth regulators (PGR) and elicitor treatments on the alkaloid profile variation of Catharanthus roseus was investigated in the present study. The PGR used were paclobutrazol (PBZ), gibberellic acid (GA3) and Pseudomonas fluorescens elicitors (PF Elicitors). The estimated alkaloids were ajmalicine, catharanthine, tabersonine, serpentine and vindoline. In roots, the ajmalicine content increased significantly under all the treatments on all sampling days. In roots, the catharanthine contents increased with the age in control and growth regulator treatments, but the increase was not prominent and significant in PGR treatments when compared to controls. The serpentine contents of the plant increased with PGR treatments, but the increase was more prominent in PBZ treatments when compared to other treatments. The increase was in the order PBZ > PF Elicitors > GA3. C. roseus never showed any significant increase in tabersonine contents in the roots under GA3 treatments, but it increased significantly under PBZ and PF Elicitors when compared to control plants. The root vindoline contents increased with PBZ and PF Elicitors treatments but the decreased under GA3 treatments when compared to control plants. Our results have good significance, as these increases the secondary metabolites of this traditional medicinal plant.

For the past several years, several techniques of physiology have been applied to overcome the water deficit and drought stress in field crops. However little information is gained on the response to PBZ and ABA treatments under drought stress and their ameliorative actions on Sesamum. So a study was carried out to understand the effect of PBZ and ABA on drought stress amelioration in Sesamum indicum L. The main aspects studied were the non-enzymatic antioxidant changes in different parts of treated, drought stressed as well as control plants. The non-enzymatic antioxidants (ascorbic acid and tocopherol) were extracted and estimated. The non-enzymatic antioxidant molecules like ascorbate and α-tocopherol showed significant increase under drought condition in Sesamum indicum. PBZ caused significant enhancement in thes e antioxidant enzymes under drought stress and also in well-watered conditions. It is not so with ABA treatment. ABA slightly reduced the non-enzymatic antioxidant contents. From the results, it can be concluded that, these growth regulators are better suited as stress ameliorating agents in gingelly.

A pot culture experiment was conducted to estimate the effect of cobalt (0, 50, 100, 150, 200 and 250 mg kg-1soil) on morphological parameters, drymatter production, yield and yield components of soybean. Pot culture experiments were conducted during January 2006 to April 2006. Periodical observations were made to record the various morphological parameters, dry matter production and yield responses of soybean. From the results, it is observed that, cobalt at lower concentrations have some beneficial values on soybean.