Plant biostimulants are diverse substances and microorganisms used to enhance plant growth. The global market for biostimulants is projected to increase 12 % per year and reach over $2,200 million by 2018. Despite the growing use of biostimulants in agriculture, many in the scientific community consider biostimulants to be lacking peer-reviewed scientific evaluation. This article describes the emerging definitions of biostimulants and reviews the literature on five categories of biostimulants: i. microbial inoculants, ii. humic acids, iii. fulvic acids, iv. protein hydrolysates and amino acids, and v. seaweed extracts. The large number of publications cited for each category of biostimulants demonstrates that there is growing scientific evidence supporting the use of biostimulants as agricultural inputs on diverse plant species. The cited literature also reveals some commonalities in plant responses to different biostimulants, such as increased root growth, enhanced nutrient uptake, and stress tolerance.

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Agricultural uses of plant biostimulants

Seaweed extracts as biostimulants in horticulture

Mosquitoes act as a vector for most of the life threatening diseases like malaria, yellow fever, dengue fever, chikungunya ferver, filariasis, encephalitis, West Nile Virus infection, etc. Under the Integrated Mosquito Management (IMM), emphasis was given on the application of alternative strategies in mosquito control. The continuous application of synthetic insecticides causes development of resistance in vector species, biological magnification of toxic substances through the food chain and adverse effects on environmental quality and non target organisms including human health. Application of active toxic agents from plant extracts as an alternative mosquito control strategy was available from ancient times. These are non-toxic, easily available at affordable prices, biodegradable and show broad-spectrum target-specific activities against different species of vector mosquitoes. In this article, the current state of knowledge on phytochemical sources and mosquitocidal activity, their mechanism of action on target population, variation of their larvicidal activity according to mosquito species, instar specificity, polarity of solvents used during extraction, nature of active ingredient and promising advances made in biological control of mosquitoes by plant derived secondary metabolites have been reviewed.

Plant extracts as potential mosquito larvicides

Antibacterial and antifungal activities of thymol: A brief review of the literature

Ester bond hydrolysis of membrane phospholipids by Phospholipase A2 and consequent release of fatty acids are the initiating steps of inflammation It is proposed in this study that the inhibition of phospholipase A2 is one of the ways to control inflammation Investigations are carried out to identify the mode of inhibition of phospholipase A2 by the n-hexadecanoic acid It may help in designing of specific inhibitors of phospholipase A2 as anti-inflammatory agents The enzyme kinetics study proved that n-hexadecanoic acid inhibits phospholipase A2 in a competitive manner It was identified from the crystal structure at 25 A resolution that the position of n-hexadecanoic acid is in the active site of the phospholipase A2 The binding constant and binding energy have also been calculated using Isothermal Titration Calorimetry Also, the binding energy of n-hexadecanoic acid to phospholipase A2 was calculated by in silico method and compared with known inhibitors It may be concluded from the structural and kinetics studies that the fatty acid, n-hexadecanoic acid, is an inhibitor of phospholipase A2, hence, an anti-inflammatory compound The inferences from the present study validate the rigorous use of medicated oils rich in n-hexadecanoic acid for the treatment of rheumatic symptoms in the traditional medical system of India, Ayurveda

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1747-0285.2012.01418.x

Anti‐Inflammatory Property of n‐Hexadecanoic Acid: Structural Evidence and Kinetic Assessment

Antibacterial and antifungal activities of fatty acid methyl esters of the blind-your-eye mangrove from India

Antibacterial and antifungal activity of Syzygium jambolanum seeds.

Effect of seaweed extracts on the growth and biochemical constituents of Vigna sinensis.

Objectives: The fatty acid methyl esters (FAME extract) from Sesuvium (S.) portulacastrum was studied for its fatty acid composition and antimicrobial activity against human pathogenic microorganisms. Materials and Methods and Results: The gas chromatographic analysis of FAME extract re- vealed the presence of palmitic acid with the highest relative percentage (31.18%), followed by oleic acid (21.15%), linolenic acid (14.18%) linoleic acid (10.63%), myristic acid (6.91%) and behenic acid (2.42%). The saturated fatty acids were high- er than the unsaturated fatty acids. FAME extract showed the highest antibacterial and anticandidal activities and moderate antifungal activity against the tested microorganisms. The highest mean zone of inhibition (16.3 mm) and the lowest MIC (0.25 mg/ml) and MBC (0.5 mg/ml) values were recorded against Bacillus subtilis. The lowest mean zone of inhibition (8.8 mm) and the highest MIC (8 mg/ml) and MFC (16 mg/ml) values were recorded against Aspergillus fumigatus and As- pergillus niger. Conclusions: The results of the present study justify the use of S. portulacastrum in traditional medicine and the FAME extract can be used as a potential antimicrobial agent against the tested human pathogenic microorganisms.

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Antibacterial and antifungal efficacy of fatty acid methyl esters from the leaves of Sesuvium portulacastrum L.

The early fourth instar larvae of Culex quinquefasciatus, reared in the laboratory were used for larvicidal assay with leaf extracts of Vitex negundo, Vitex trifolia, Vitex peduncularis and Vitex altissima. The methanol extracts of the four species possessed varying levels of larvicidal nature. The highest larvicidal activity was found with the extract of V. trifolia (LC50 = 41.41 ppm) followed by V. peduncularis (LC50 = 76.28 ppm), V. altissima (LC50 = 128.04 ppm) and V. negundo (LC50 = 212.57 ppm).

M. Chandrasekaran

Papers

Antibacterial and antifungal activities of fatty acid methyl esters of the blind-your-eye mangrove from India

Antibacterial and antifungal activity of Syzygium jambolanum seeds.

Effect of seaweed extracts on the growth and biochemical constituents of Vigna sinensis.

Antibacterial and antifungal efficacy of fatty acid methyl esters from the leaves of Sesuvium portulacastrum L.

Differential larvicidal efficacy of four species of Vitex against Culex quinquefasciatus larvae.