Evaluation of Anti-Inflammatory Effects of Flavonoids Present in Pomelo Peel Extracts
Eva Cai
Collingwood School
Floor Location : S 006 H

The purpose of this project is the identification and assessment of effectiveness of anti-inflammatory compounds - particularly flavonoids - present in pomelo peels. Previous studies have identified various bioactive compounds, such as flavonoid and pectin, that are abundant in pomelo peels. For example, flavonoids in pomelo extracts are experimentally shown to be preventative of metabolic syndrome.
If flavonoids identified in the pomelo peels are experimentally proven to have anti-inflammatory properties, it could be a potential substitute of current over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs). Furthermore, because the peels of pomelo fruits are often disposed, identifying anti-inflammatory compounds in pomelo peels would greatly improve their usage and importance. However, few research has been conducted to verify the anti-inflammatory effect of pomelo (or other citrus) peel extract on animal models.
The effects of flavonoids are tested on the model species of redworms (Eisenia fetida). Intestinal inflammation is induced by feeding carrageenan powder to an experiment group. A pilot experiment is conducted to determine whether redworms would consume the carrageenan powder as a part of its diet. The pomelo peel extract is obtained by drying the pomelo peels and powdering it, extracting with 80.9% ethanol and 14.1% methanol, and then filtering the resulting solution. The extract powder are isolated by using a rotary evaporator an then freeze drying the evaporated solution.
Experimental groups are set up to observe how the pomelo peel extract plays a role in reducing the inflammatory symptoms caused by carrageenan. The experimental groups include: soil, soil + carrageenan, carrageenan, soil + extract, soil + extract + carrageenan; each group contains 20 worms. A behaviour protocol is developed to evaluate the behaviour of the worms before and after eating the carrageenan, and whether the diet with pomelo peel extract would ameliorate the behaviour. Markers in the behaviour protocol include: time spent moving and time spent still (in a hour), time spent around the edges of the petri dish and in the centre of the petri dish, pattern of movement, etc. The groups will be monitored for five days.
A second experiment that models general inflammation is performed by puncturing worms in their middle using a dissecting pin, and then feeding the two groups of worms diets of soil and soil + extract, respectively. The healing time of the soil + extract group is compared to that of the control (soil) group. Microscopic images of the wound are taken each day until fully healed, which is compared between the two groups.
Although the experiment is not fully completed at the time of writing, it is predicted that the flavonoids will have a positive effect on treating inflammation: it would improve the behaviour of the carrageenan-fed worms, and decrease the recovery time of the punctured worms. Future improvements include analyzing the effects of flavonoids on a molecular level by monitoring the levels of markers present in inflammation - for example, the signalling of toll-like receptor 4 (TLR4) in intestinal disease.