Indian Journal of Geo Marine Sciences Vol.46 (04), April 2017, pp. 663-667 Review Article Potential pharmaceutical and biomedical applications of Diatoms microalgae - An overview Palaniselvam Kuppusamya, Ilavenil Soundharrajana, Srisesharam Srigopalrama, Mashitah M. Yusoffa, Gaanty Pragas Maniamb, Natanamurugaraj Govindanb*& Ki Choon Choia* aCell biology Laboratory, Grassland and Forage Division, National Institute of Animal Science, RDA, Seonghwan-Eup, Cheonan-Si, Chungnam 330-801, Republic of Korea bBiomaterial and Biosensor Laboratory, Faculty of Industrial Sciences and Technology, Universiti Malaysia Pahang, LebuhrayaTun Razak 26300, Gambang, Kuantan, Malaysia *[E.mail: [email protected], [email protected]] Received 06 November 2013; revised 26 November 2013 Naturally occurring two girdle band valves of diatoms are made up of siliceous material as covering the cell wall of the organism. The unicellular microalgae are coming under bacillariophyceae groups and identified more than 10,000 species. It found in various natural sources such as sea water, river, ponds and wastewater. Diatom is very small in size approximately 20- 200 nm. The microalgae diatoms are used in pharmaceutical and biomedical industries due to the smaller in size and structure. Also, the nanoscale structures of diatom frustules are highly observed and using as a drug delivery material for therapeutic approaches. On other hand, diatom is one of the main sources of the food chain in the marine system. It is the photosynthetic organism which synthesis the required foods themselves by photosynthesis. Diatoms utilize the atmospheric CO2 and releases oxygen through the biochemical process and maintain the atmospheric CO2 level when the biological process occurred. In addition, the diatom microalgae contain the high amount of unsaturated fatty acids (50-60%), lipids, polysaccharides and other biomolecules which are used in the chronic and acute diseases treatments. In this review, we are mainly focused on the diatoms for therapeutic applications in different pharmaceutical and biomedical arena. [Keywords: Diatom, Secondary metabolites, nanomaterials, bio-fuel] Introduction the global carbon fixation in carbon and silicon Diatoms are most diverse and cycles. Also, diatoms are involved in carbon spectacular nanostructure cell wall organisms sequestration which is uptake carbon dioxide which also have various bio-geo chemical and sunlight in the environment to produce properties. Diatoms are mainly classified into oxygen. The microalgae diatoms are potentially two types based on the valve face of the diatom candidate to absorb unlimited nitrogen and frustules. The diatom frustules were constructed carbon from natural resources. The microalgae with pores (areolae), spines hyaline areas, diatoms are dynamically focused on the biofuel processed and other characteristic features. The industry as an alternative energy production two types of classification are centrales based on easy for biomass cultivation in large (biddulphiales) and pennales (bacillariales). The scalable. Particularly, the diatoms have a high centrales valve striae arranged basically in content of oils, fatty acids, steroids and other relation to a point and central areola be likely to primary and secondary metabolites. The highly appear symmetrical. The pennales have valve branched metabolites such as long chain fatty striae arranged in relation to a line and tend to acids and lipids are mainly useful for appear zygomorphic (bilaterally symmetrical)1. pharmaceutical applications and biodiesel The photoautotrophic type of diatoms is production2. The decomposition of diatoms mainly involved in various bio-geochemical frustules were sinking to the bottom of the sea cycle and it is main ocean carbon producers. that sediment of diatom called diatomite or Diatom plays a main role in the ocean diatomaceous earth. These materials have found biogeochemical regulation, mainly to contribute under the sea and studied extensively. The *Corresponding authors 664 INDIAN J. MAR. SCI., VOL. 46, NO. 04, APRIL 2017 materials were using for different commercial microbial agents and also inhibit the pathogens uses such as mineral filters, sorbents, anti- replication in the host. The biosynthesis caking agents, abrasives, insulation materials approach is generally flexible and diatoms can and so on.3 This review demonstrates the be applied for the preparation of a wide range of biomass of microalgae diatoms for nanomaterial different metallic nanoparticles such as gold, syntheses and their potential pharmacological, silver and platinum. Diatoms mediated gold and biomedical and environmental applications. silver metal nanoparticles are exhibits strong cytotoxicity against harmful microorganisms. Diatoms frustules using as drug delivery The mass of diatom culture Navicula atomus material and Diadesmis gallica were used for synthesis Very often, we are use water soluble of EPS gold –silica bionanocomposites by eco- drugs for treating different acute and chronic friendly method5. Also, the freshwater diatom diseases. So, it cannot cross the biological Stauroneis sp. synthesized silicon-germanium membrane due to the poor solubility and nanoparticles in specific size and shapes by stability nature of drug molecule. However, the green chemistry way6. The diatom frustules biological derived nano materials exhibit novel enhanced the surface plasmon resonances of properties such as solubility in both water and silver nanoparticles due to the silicon made organic solvents. As such, scientists nowadays frustules in the cell wall of microalgae. The focused on encapsulating drug with polymers to micro algae derived nanomaterials have effectively bind and act an active site different therapeutic properties against chronic particularly. The encapsulated nanodrugs are diseases and its due to the synergic effect of well action in particular targeted site as well, bioactive compounds surface of the synthesized reduces the soluble nature of the drug delivery metal nanoparticles7. systems. Since it is nanosized, it can cross the biological barriers easily. On the basis, the Bioactive constituents in marine diatoms diatom nanostructure frustules using as drug Diatom contains a wide range of carrier materials for drug delivery applications. secondary metabolites such as lipids, esters, The two main steps in the drug release using sterols and acyl lipids, flavonoids and proteins8,9. diatom frustules were observed. Firstly, the The diatom cell membrane encompasses of free release of the drug is on active site and then, fatty acids and silicon materials. Also, the slow and sustained release of drugs over the diatom is a one of the rich sources of lipids, couple of weeks. The natural material of diatom saturated and unsaturated fatty acids. These silica can be successfully applied as a drug bioactive metabolites can be act as anticancer, carrier for both oral and implant drug-delivery antibacterial and antioxidant drugs. Table 2 applications3. So, the diatom is considerable shows the identified various bioactive interest in developing biodegradable polymeric metabolites from marine diatoms. The two encapsulated nanoparticles for drug delivery4. monogalactosyl diacylglycerol were isolated Therefore, the diatom frustules are mainly use from the marine diatom Phaeodactylum as drug delivery materials in delivery system. tricornutum and the compounds effectively Fig. 1 shows the various applications of marine using for apoptosis based anticancer drug10. In diatom in diverse fields. addition, the O. mobiliensis and P. angulatum marine diatom have the highest amount of Nanoparticles synthesis using diatoms phenolic content which reduces the free radical The integration of nanoparticles with scavenging formation from the metabolic biological molecules has lead to the pathways11. development of potential anticancer and antimicrobial agents. Recently, the diatoms have Nutritional value of diatoms reported the production of gold and silver The biomass production of diatom is a metallic nanoparticles via eco-friendly method. very important in the food and pharmaceutical Diatom biosynthesis of metallic industries. The artificial cultured medium nanoparticles using extra and intra cellular provides sufficient strength to grow microalgae extract by environmentally benign method. The in large scale24. The algal nutrient medium diatom biosynthesized gold nanoparticles are contains various minerals such as N2, Cl2 which effectively involves apoptosis induction, anti- tends to modify the amount natural lipid content KUPPUSAMY et al.: PHARMACEUTICAL AND BIOMEDICAL APPLICATIONS OF DIATOMS MICROALAGE 665 in the microalgae biomass production. On other compounds that are used in various therapeutic hand, salinity stress is also an important factor applications16. which represents the increasing metabolites The algae extracts were found to production of brown and green algae also contain higher percentage of eisosapentaenoic diatoms12. acid and polyunsaturated fatty acid. These Diatom contains different nutritional compounds play a key role in antimicrobial values materials mainly essential defense mechanism. Similarly, high levels of macromolecules, enzymes and toxins. So, the palmitoleic acid and other bioactive compounds microalgae as a good source animals feeds and found in the P. tricornutum, it is active against nutritional food for humans. Many research gram+ human pathogens. The marine studies attempted to increase nutritional value of diatom Odontella