Medicinal plant resources within Indo-Burmese mega-biodiversity region
Contd from previous issue
They react rapidly with other compounds capturing electrons needed to gain stability. Molecules without unpaired electrons themselves become free radicals and the beginning of a chain reaction occurs. A free radical can either obtain an electron by removing it from another molecule or bind itself to another forming adducts or also be donated with a hydrogen atom to stabilize the delocalization of the radical.
Free radicals are not all bad as they are involved in several vital biological processes, particularly signalling pathways in vivo but they create a menace when they are left untamed. Normally, different forms of free radicals optimally exist in the cells to help harmonization of various physiological functions and are quenched by an integrated anti-oxidant system in the body. However, destructive effects leading to various disorders occur due to excess production of these free radicals. Exposure to ionizing radiations such as X-ray, ã-ray, á-ray and ultrasound during medical diagnostic procedures, natural background radiations and cosmic rays knowingly or inadvertently can generate free radicals and lead to associated adverse effects. People living in areas where there are rich deposits of radioactive elements such as uranium (235U), thorium (232Th) and plutonium (239Pu) are exposed to natural background radiations round the year which causes accumulation of free radicals. Frequent trans-continental fliers are exposed to cosmic rays thereby getting a lot of free radicals generated within their cells in the body. Apart from these ionizing radiations, free radicals can be generated through pollutants, cigarette smoking, tobacco chewing, consumption of marijuana, opium and drugs, consumption of antibiotics, exposure to pesticides and fungicides, etc. Besides, there are high levels of radioactive potassium (40K) present in the materials of the concrete houses we live in.
Reactive oxygen species and reactive nitrogen species are produced which on accumulation in the body can lead to damage of biomolecules such as proteins, lipids and DNA resulting into initiation of oxidative stress. In fact, everyone needs anti-oxidants as we are exposed to a number of ROS and RNS generating factors present in our environment. We need to enrich the anti-oxidant pool within the physiological system so that a better defensive strategy is created. Physiological system contains defensive mechanisms against free radical attacks such as the superoxide dismutase and glutathione peroxidase as well as host of small anti-oxidant molecules such as vitamins A,C,D,E, glutathione, thioproline, curcumin, methylxanthines, flavonoids, phytosteroids and phenolic compounds. However, these molecules alone cannot destroy the reactive species altogether. Reinforcements have to be made through dietary intakes to create a proper defensive balance within the cellular environment.
We consume various plant products which are rich in anti-oxidant without even knowing which phyto-nutrients are contained in them. Spices and herbs provide foods with flavors and food preserving power, including antiseptic and anti-oxidative activities. Natural anti-oxidants of spices and herbs are generally classified as vitamins, phenolic compounds including flavonoids and phenolic acids, and volatile compounds. Extracts of various spices and herbs possess anti-oxidative activities, and many antioxidative compounds have been identified. Fruits and vegetables are known to contain a variety of differentanti-oxidant compounds such as ascorbic acid, tocopherol, glutathione and carotenoids which may all contribute to protection against oxidative damage. It has been known that phenolics from edible fruits are effective in vitro anti-oxidants. Some reducing compounds or anti-oxidants such as ascorbic acid and glutathione are very efficient in controlling enzymatic browning. With the increasing realization of health hazards and toxicity associated with indiscriminate use of synthetic drugs and antibiotics, interest in the use of plants and plant-based drugs has been in vogue throughout the world. Therefore, plants play an important role in the introduction of novel therapeutic agents, and also drugs from the higher plants continue to occupy an important niche in modern medicine.
The Indo-Burmese mega-biodiversity region has several plants which could be used in preventive aspects of free radical induced damages are wildly and widely distributed. The comparison of aesthetic values of these plant families makes us realize the role of biodiversity in tailoring the functions of its elements according to the various needs of mankind. Apart from these plants, there are a lot more plants in which phytochemicals are distributed in the form of bio-active molecules which have anti-oxidative as well as other healing properties. Free radical research or redox biology has led the role in the screening of anti-oxidative properties, understanding the mechanisms of free radical reactions, particularly anti-oxidant interactions and taming the molecular rogues present. New avenues in mining the treasures scattered in the wilderness of biodiversity rich areas in the form of biomolecules which are considered to be solutions to a number of human ailments. Principal bioactive molecules from plants (found in Manipur) such as Acorus calamus, Aegle marmelos, Alstonia Scholaris, Alpinia allughas, Averrhoa carambola, Boesenbergia rotunda, Centella asiatica, Costus Speciosus, Curcuma longa, Emblica officinalis, Hedychium coronarium, Kaempferia galanga, Mentha piperita, Ocimum sanctum, Oroxylum indicum, Paris polyphylla, Parkia timoriana, Panax pseudoginseng, Phyllanthus niruri, Rosemary officinalis, Syzygiumcumini, Terminalia arjuna, Terminalia chebula, Tinospora cordifolia, Trigonella foenumgrecum, Zanthoxylum armatum and Zingiber montanumhave been medicinally utilized buttheirmolecular mechanisms remain yet to be fully investigated.
It has been considered that Mediterranean food is the most nutritious food. However, only a few major food plants are incorporated in it. On the other hand, people living in the north-east India and especially in Manipur are reported to consume more than a hundred foodplants including non-conventionals either raw or cooked. This points to the fact that these people consume a rich diet containing phytonutrients which contain ascorbic acid, polyphenols, flavonoids, phytosterols, tocopherol, carotenoids and a variety of other bio-active compounds round the year. Perhaps, this may be one of the reasons that the people in this region are more agile, sportive and energetic having potential to lead in different arenas.
During the past, the importance of anti-oxidants and other phytonutrients were not felt the way it is today. Today, we have gone very far from nature, shifting our niches to concrete forests and dependent upon junk foods which have created a deep impact on our lifestyles in terms of health and disease resistance. Human beings have become more prone to number of diseases/ disorders, and we have acquired low resistance towards adverse environmental conditions. Before it is too late, we just need to go back to the wilderness in search of the elixir of life with the updated knowledge and skills and harness it without over-exploiting the riches of biodiversity.
The writer is Former Emeritus Professor, Manipur University, Imphal