Algae are a type of photosynthetic organism that can be found in both marine and freshwater environment. These organisms are among the fastest growing because they have a short life cycle.
By Ghulam Abbas Narejo*, H.U Khan, Aneel A. Gilani, Zil-E-Haleefa, Amir Hussain
They use various pathways to fix atmospheric CO2 and efficiently utilize nutrients to convert it into biomass.Being chief producers in the word, algae play enormous role i.e., photosynthesis, liberation of oxygen and synthesis of valuable compounds. Now adays these compounds are widely used in field of medicines and pharmacy.In few years, a focus has been shifted towards these organisms due to their food, fuel production capability and medicinal properties. Microalgae are source of immense bioactive compounds that can be exploited for commercial applications. Algae provide a wide range of pharmaceutical products, proteins, vaccines, nutrients that otherwise are not available or are very costly to produce from animal and plant sources. Various pharmaceutical products from microalgae have high value but its commercialization is still in its infancy and but in near future can be seen as a gateway to multibillion dollar industry.
Being natural remedies of disease, micro and macro algae are variously used as: antioxidants, source of vitamins, anticancer and antitumor agents, anticoagulants and antithrombic agents, source of anti-inflammation, anaesthetics, antipyretics, cough remedies, thirst quenching remedies, wound healing compounds, source of antibiotics, antiviral compounds, food supplements, nutraceuticals, vermifuges, source of biocosmetics, thalassotherapy and obstetrical uses etc. Some disease also treated while using algal products such as gout, gallstones, goiter, hypertension, diarrhoea, constipation, dysentery, burns, skin disease, lungs disease, sperm discharge etc.
Few important activities are as under:
Antiviral activity:
It is recently reported that cyanobacteria play vital role as treatment of against many viral diseases. Cyanovirin-N, a viricidal agent, extractedfrom cyanobacteria that inhibited the cellular infections caused by HIV-1by blocking the interaction of viral glycoprotein gp120 with CD4. Spirulina platensis showed antiviral activity against various viruses as Human cytomegalo viruses, Herpes simplex and measles virus by blocking their entry due to the presence of sulphur containing polysaccharide. Moreover, the enhanced antiviral activity due to sulphur containing polysaccharides has also been shown by a red alga Porphyridium by blocking the adsorption of virions against HSV-1, HSV-2.
Anticancer and antitumour activity:
Various compounds have been isolated from algae having anticancer activities. There are many bioactive compounds reported in algae which inhibited and destroyed the production of cancerous cells by apoptosis. Poteriochromonas malhamensis has shown inhibition of enzyme activity of protein tyrosine kinase due to presence of a novel compound chlorosulfolipid. There are many cyanobacteria which are promising producers of bioactive compounds and capable of destroying cancer cells by process of apoptosis, affecting cell signalling by activation of signalling enzymes of protein kinase C family. These compounds are more effective against implanted lymphocytic leukaemia and lung carcinoma. Recently,Algal extracts from several marine blue green algae species, including Lyngbya majuscule, Oscillatoria nigroviridis, and Schizothrix calcicola, contain debromoaphysiatoxin which significantly inhibited Lymphotic mouse leukaemia. Several seaweed decoctions from Sargassum sp. and Laminaria sp. have been used in Chinese herbal medicine to treat cancer.
Antioxidant activity:
In current scenario, physical as well as mental stresses are very common. This leads production of free oxygen radicals. Superoxide and hydrogen radicals are very common oxygen radicals which cause the oxygen cytotoxicity and hijacks the cellular metabolism by triggering lipid peroxidation. Damage of DNA, inhibition of protein synthesis are very common abnormal processes caused by ROS (reactive oxygen species). These damages cause many diseases like; cancer,arteriosclerosis, reperfusion and hepatic injury. However, algae-derived carotenoids play important role against mitigation of ROS based damages. Carotenoids such as β-carotene, astaxanthin, and canthaxanthin are naturally abundant in many algae. Dunaliella salina, a green halophilic flagellate, accumulates more than 10% of its dry weight as β-carotene, which is commercially exploited in a number of countries. Chrococcum is a common green alga that is rich in astaxanthin. Other marine algae, such as Sargassum thunbergii and Laminaria japonica, are used to extract antioxidant-rich sulphated polysaccharides. Seaweeds are also naturally high in reactive antioxidant molecules such as ascorbate and glutathione, as well as carotenoids (α- and β-carotene, fucoxanthin, astaxanthin), mycosporine like amino acids, catechines (e.g., Catechin, epigallocatechin), gallate, phlorotannins (e.g., Phloroglucinol), eckol, and tocopherol (α-, γ-, δ- tocopherols) etc.
Antibiotic activity:
Antibiotic-active chemical compounds are widely used in the treatment of disease. Haloforms, halogenated alkanes and alkenes, alcohols, aldehyde, hydroquinones, ketones, and terpenoids are antibiotic compounds found in macro, marine algae such as brown and red algae. And are used in the commercial synthesis of antibiotics. Chlorellin from Chlorella and acrylic acid from Phaeocystis pouchettii are two well-known compounds extracted. From Bryopsis sp. depsipetides Kahalalide A and F have been extracted which are shown to be effective against Mycobacterium tuberculosis (tuberculosis disease). These compounds will be used to treat lung cancer, tumours, AIDS, and other diseases in the future. Sulphated polysaccharides are well-known for their anticoagulant and antithrombin activity. As a result, anticoagulant sulphated fucans derived from Fucus vesiculosus and Ascophyllum nodosum have been identified.
Anti-inflammatory activity:
Inflammation activity is frequently caused by pathogens or other causes and results in tissue death. As a result, several people die. Many side effects have been observed with chemically synthesised drugs. For example, aspirin can cause stomach bleeding, acetaminophen can cause liver damage, Cox-3 inhibitors Vioxx and Celebrex can cause heart problems, and nonsteroidal anti-inflammatory drugs have been linked to several deaths each year. Therefore, bio-synthesised anti-inflammatory compounds are actually needed. Several compounds derived from aquatic macro algae have recently been discovered to elicit an immunological response in humans. Sulfated polysaccharides, specifically fucoidins extracted from brown algae, alkaloids (Caulerpin I, II, III) extracted from red and green seaweeds, carotenoids (fucoxanthin and astaxanthin), Phaeophytin A and Vidalols A and B are anti-inflammatory compounds isolated from macroalgae that are widely used in anti-inflammatory drugs.
Anticardiovascular disease activity:
Cholesterol is a major contributor to high blood pressure and cardiovascular disease. Algal polysaccharides such as alginates, carrageenans, funorans, fucoidans, laminarans, porphyrans, ulvans, and others have been found to have hypocholesterolemic and hypolipidemic activity by reducing cholesterol absorption in the gut. This activity is frequently linked to a hypoglycaemic response as well as an increase in faecal cholesterol content. Systolic blood pressure is also reduced by algal polysaccharides. In addition, it lowers total cholesterol, free cholesterol, triglycerides, and phospholipids in the liver. All of these activities help to lower the risk of cardiovascular disease.
Nutraceutical activity:
Nutraceuticals are becoming increasingly popular as health products.Dietary fibres are extremely beneficial in many health issues such as constipation, weight gain, vitamin deficiency, and so on. Seaweeds and other algae are high in dietary fibre, as well as vitamins and minerals. As a result, consumption has recently increased. Food value, flavour, colour, and texture are all reasons for consumption. Seaweeds are high in vitamins, including vitamin C at levels comparable to citrus fruits, as well as vitamins A, D, B1, B12, E, riboflavin, niacin, pantothenic acid, and folic acid. Also, provide all of the trace elements required for human nutrition.
Vermifuge activity:
The use of seaweeds as a vermifuge or anthelmintic is a very old concept. Digenea is a red alga that has been used as a vermifuge for over a thousand years. Kainic acid (KA) is the active compound that causes neuromuscular block in the worm. It forces the Ascaris out of the patient at a dose of 5-10 mg without causing any side effects. In Japan, Kainic acid (KA) is combined with santonin (a compound isolated from the flowering plant Artemisia maritime L. Domoic acid–containing extracts of Digenea simplex and Chondriaarmata have also been used as anthelmintic agents for centuries.
In Pakistan, several research institutes, organizations are working on extraction of valuable compounds from algae in order to produce biomedicines to cure certain deadly disease like AIDS, cancer and tuberculosis. In near future this practice will be so common to meet with public demands on reasonable price.