Essay Example on The article reviews the studies on anti inflammatory effects of herbal Extracts

In vivo and in vitro experimental models to investigate the anti inflammatory activity of herbal extracts Imtiyaz Ansari1 VanitaKanase2 Mateen Sayed3 Inayat Kabir 1Department of pharmacology ABSTRACT The article reviews the studies on anti inflammatory effects of herbal extracts with emphasis on different experimental models that are frequently used to test the in vivo anti inflammatory activity of herbal components Oedema granuloma and arthritis models are used to test the anti inflammatory activity of plant extracts whereas formalin or acetic acid induced writhing test and hot plate methods are the most repeatedly used to evaluate anti nociceptive potentials of the herbal extracts Although adjuvant induced and collagen induced arthritis models are also quite efficient they have been used seldom to evaluate anti inflammatory tendencies of the herbs Here we suggest a double positive reference model using both steroid and non steroidal anti inflammatory drugs at the same time instead of using only one of the either Key Words Anti Inflammatory Herbal Extracts Experimental models 

1 INTRODUCTION Inflammation is the response of the living system to cell injury It is a protective mechanism that helps the body to identify and neutralize the noxious stimuli like bacterial pathogens toxic chemicals and cancerous cells by increasing the blood flow to the area of tissue injury Inflammation is also a great hazard to the patient It increases the ailment and sufferings of the patient due to pain and morbidity 1 Arachidonic acid cyclooxygenase and lipoxygenase mediated activation of local inflammatory mediators such as leukotrienes prostaglandins prostacyclin thromboxane A2 PAFs play a key role in tissue destruction and pain associated with inflammation 1 2 Inflammation often results into pus formation that may hinder the absorption of different antibiotics into the affected tissue that lead to the aggravation of tissue destruction So it becomes mandatory to administer anti inflammatory drugs to cure a number of disorders such as infectious diseases in combination with antibiotics Although a number of different synthetic and semi synthetic drugs are in use today to combat inflammation there has always been a thirst to search for the natural anti inflammatory constituents from various plants spices 

The medicinal importance of spices and herbs is known since ancient times Most of the today s allopathic medicines are either consisted of herbal extract or these are the semi synthetic derivatives of herbal products Since prehistoric times herbs are famous in traditional medicine for their anti inflammatory anti nociceptive and immunomodulatory activities Many researchers have directly tested the inhibitory effect of different herbal extracts on the production of inflammatory mediators by using different cell culture techniques 3 4 5 Such in vitro studies are helpful in developing an understanding of the mechanism of anti inflammatory activity of herbal components however most of such in vitro studies are secondary to a preliminary in vivo evaluation of anti inflammatory properties of plant extracts 6 7 8 9 Different researchers have used different experimental models to evaluate the anti inflammatoryactivity of herbal extracts Here we have summarized all those in vivo in vitro methods that are repeatedly being used to evaluate the anti inflammatory activity of herbs and spices 

2 IN VIVO SCREENING MODELS In these screening methods the potency of anti inflammatory drug is measured by inducing the inflammation in experimental animals like rats mice monkeys dogs of either sex Before starting any in vivo assay it is essential to study the oral acute toxicity study of the selected drug In this maximum tolerated and minimum toxic dose are calculated by injecting the test dose at an interval of 2hrs in 10 50 100 200 2000 mg kg patterns Experimental animals Some researchers have used big ear albino rabbits 10 most of them have preferred using mice and rats to test the anti inflammatory activities of herbal extracts Different types of mice and rats that are frequently used to test the anti inflammatory effect of herbs include ICR mice 6 7 8 11 12 13 Sprague Dawley SD rats 6 11 13 14 15 16 ddY mice 2 BALB c 18 and its sub strain BALB cj mice 12 C57BL 6 commonly called as black 6 4 Swiss albino mice 19 20 albino rats 21 and Wistar rats 20 22

The animals are allowed a free access to food Laboratory chow and tap water ad libitum They are accommodated in a specific pathogen free animal facility in a laminar air flow room at a suitable temperature of 22 1 C and 40 60 RH in a light dark cycle of 12 hours 6 11 12 for two weeks or more Types of screening methods Based on the symptoms observed during inflammation in vivo screening methods for anti inflammatory drugs are characterized into three phases Acute or transient phase In this phase vasodilation and increased capillary permeability are observed Sub acute phase In this infiltration of leukocytes phagocytes in blood are observed Chronic inflammatory phase Here granuloma that is tissue degeneration and fibrosis observed In vivo screening methods 1 Carrageenan induced paw oedema in rats A solution of carrageenan in saline is injected subcutaneously in rats induces an acute swelling that becomes maximal after 3 5 hours of the injection and subsides by 24 hours Winter et al 1962 Otterness and Moore 1988 The inflammation produced in this can be used to measure the production of inflammatory mediators at sites of inflammation the anti inflammatory properties of nonsteroidal anti inflammatory drugs NSAIDs and the efficacy of alleged analgesic compounds to reverse cutaneous hypersensitivity This method elicits and measure carrageenan induced inflammation in the footpad which can evident as oedema and hypersensitivity