Staff PhD

Characterization of bioactive compounds in plants with anti-inflammatory effect

Gaik Ming Khoo

Background

Inflammation is a complex biological response of vascular tissues to injury, involving migration of leukocytes and damage to local tissues. The response is characterized by pain, fever, redness swelling, cell influx and loss of function. When inflammation system of body is activated by stimuli, arachidonic acid (AA) is released from the cell membrane phospholipids by phospholipase (PL) A2. AA is then transformed by cyclooxygenase (COX) enzymes into PGG2, and further metabolism to PGH2, the primary form of all other prostaglandin (PGs). Prostaglandin E2 (PGE2) is one of the major metabolites produced in the inflammatory process. PGE2 is one of the important mediators of inflammation, by contributing to induction of fever, increasing vascular permeability and vasodilatation, and enhancing pain and.

COX enzymes, which catalyst the conversion of AA to PGs, are the key role in regulation of inflammation. COX-1 is considered a constitutive enzyme, being found in most normal mammalian cell. The metabolites of AA derived from COX-1 are responsible for maintaining basic physiological conditions in the body, as in the case of cytoprotection of the gastric mucosa. COX-2, in contrast to COX-1, is an inducible enzyme that undetectable in most normal tissues, but becoming abundant in activated macrophage and other cells at sites of inflammation. Recent research point out the COX-2 and PGE2 are engaged in tumor development, as over expression of COX-2 and high level of PGE2 have been found in tumor cells, inhibit apoptosis, increase cell proliferation and promote angionesis.

Non-steroidal anti-inflammatory drugs (NSAIDs) are non-narcotic drugs reducing pain, fever and inflammation. The most commonly known of this group of drugs includes aspirin, ibuprofen and naproxen. Most NSAIDs act as non-selective inhibitors of the cyclooxygenase (COX) enzymes, not only inhibit the COX-2, but also the COX-1, and finally lead to undesirable side effects such as gastric problem and ulcers. Thus, selective COX-2 inhibitors are desirable for reducing risk of peptic ulceration. Present selective COX-2 inhibitors include Celecoxib, Valdecoxib, Rofecoxib, Parecoxib and Etoricoxib. Selective COX-2 inhibitors do not seem to affect other adverse-effects of NSAIDs, but some results have aroused the suspicion that there might be an increase in the risk for heart attack , thrombosis and stroke by a relative increase in thromboxane .

Use of plants has been a long history all over the world over centuries. Human widely apply this natural resource into their daily life includes cosmetics, foods, fragrance, pharmaceuticals, colors and more recently, as nutrients. Eating lots of fruits and vegetables is thought to be the best and safest way of preventing a variety of disease, include cold, influenza, and even cancer. Epidemiologic studies suggest that diets high in fruits and vegetables are strongly associated with a lower incidence of different forms of cancer. Thus, it is possible to believe that in fruits and vegetables contain various anti-inflammatory compounds including natural COX-2 inhibitors.

Rose hip, Rosa Canina, also named as Hyben in Danish, is the pseudo fruit of rose plant. Rose hip is native to Europe, North Africa and Central Asia. It is traditionally used to treat a variety of diseases, include cold, influenza, arthritis, gastric problem and etc. Rose hip is known to be rich in Vitamin C, and content other chemical compositions such as caratenoids, polyphenols, and etc. There are several clinical efficacy evidences on rose hip powder reduce the symptoms of arthritis and osteoarthritis. Most of the researches on rose hip are at the crude extraction level and fewer reports on the anti-inflammatory chemical substances. Thus, further research on isolating potential anti-inflammatory compounds rose hip should be conduct.

Aim

The aim of this project is to search for anti-inflammatory compounds from rose hip and other local vegetables and fruits, particularly COX-2 inhibitor. Apart from the direct isolation, compounds after gastric digestion and saponification of the sample will also be investigated.

Research Outline

Rose hip will be separated into 3 parts: skin, seeds and hair. Each part will be treated separately, with gastric treatment or saponification firstly, follows by extraction with organic solvents; or extraction with organic solvents and residue treated with gastric treatment or saponification. In vitro bioassay guided isolation is used to track the relevant bioactive compounds. Isolation process is assists with chromatographic method; structural elucidation is carries out with nuclear magnetic resonance and mass spectroscopy.

Selection of other vegetables and fruits for further experiment are based on primary screening. The selected of plants shall display inhibitory effects to COX-2 at a crude extract level. Different parts of selected plants will be tested separately, according to related bioassay guided isolation to track the contributing substances.