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Structural, chemical and physiological investigations of bilirubin found in seed arils of strelitzia nicolai.

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In 2009, a team of researchers from the Florida International U niversity discovered bilirubin which is an animal compound in the se ed arils of Strelitzia nicolai , commonly known as the White Bird of Paradise plant. Bilirubin is an endogenous yellowish compound that is formed following the standard catabolic pathway by the breakdown of haem. This catabolism is an essential practice in the human body as it allows for the elimination of waste products. Bilirubin is formed in humans some vertebrates and invertebrates. Previously thought to be a toxic compound if accumulated, recent ad vancements in medical sciences show bilirubin as an eff ective antioxidant. This study describes novel protocols to reveal new insights into the presence of the only animal pigment found in S. nicolai arils, the potential advantages of bilirubin found in a plant and its therapeutic value indications. In vitro a nd in vivo experim ents using the aril extract was conducted in order to assess the antioxidant , anti cancer and toxicity dosage of S. nicolai aril extract. In vitro studies showed that S. nicolai aril extract caused apoptosis in 52% of Hela cancer cell lin es. These results indicate that S. nicolai aril s extract possess conceivable chemo preventive properties. In vivo results in a rat model showe d no acute toxicity nonetheless, t hese results were inconclusive as a lengthier chronic study needs to be conducte d in order to completely rule out toxicity. An ultrastructure study of the seed arils was embarked in order to integrate supplementary knowledge The developing seeds were grouped in five stages according to seed maturity and aril colour. The arils were an alysed using light and electron microscopy. The Hall’s staining which is generally used on human tissue was modified to detect bilirubin on the surface of the aril tissue. Light microscopic results showed that as the aril matures it undergoes an atypical c olour change from opaque to yellow and finally a deep orange. This colour change might be attributed to the accumulation of bilirubin in the aril tissue. This hypothesis was further justified by cryo SEM and TEM which shows the trend of an accretion of a p igment as the aril matures. In addition, the inclination of aril maturity in S. nicolai follows an analogous prototypical pathway to that of bilirubin catabolism in humans. This study consequently highlights the potential use of S. nicolai aril extract co ntaining bilirubin and also attempts to relate aril structure with impending function.


Doctoral degree. University of KwaZulu-Natal, Durban.