Bioactive Compounds of Pili (Canarium ovatum Engl.)
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Pili (Canarium ovatum) is a tropical tree that is indigenous to the Philippines where its center of genetic diversity is located in the Bicol Region. As a nut, Canarium ovatum is considered the priced commodity, and it is often used in the confectionery industry. The pulp, which is totally discarded as waste, contains considerable quantities of bioactive compounds present in the pulp meal as well as in the oil. This chapter describes the characterization of all the parts of Canarium ovatum fruit as source of hydrophilic and lipophilic bioactive compounds with high antioxidant functionality. The exploitation of this underutilized fruit presents a great potential source of phytochemicals with antioxidants functionalities.
KeywordsAnthocyanin Antioxidant Bioactive compounds Canarium ovatum Pili
Studies revealed that Canarium ovatum fruits are rich in bioactive compounds that are good for the health. Studies indicated that the pulp contains a high source of hydrophilic phytochemicals such as polyphenols. The oil also contains high levels of lipophilic molecular species such as tocopherols, phytosterols, and carotenoids with high antioxidant properties.
2 Pili (Canarium sp.)
Canarium sp. belongs to the family Burseraceae which consist of 16 genera with more than 500 species across the tropical hemisphere and is indigenous to the Philippines [1, 2]. Bicolanos dubbed pili as the “tree of hope” owing to its many uses in which almost the entire tree parts can be exploited as a new source of income for various food, medicine, and industrial applicability. In a report issued by the Department of Agriculture Regional Field Office 5 (DA-RFO 5) , Canarium ovatum, being one of the banner commodities of the Bicol Region, solidifies its position as a profitable commodity that Bicolanos can truly benefit from.
In the Philippines, there are two Canarium sp. that are of economic importance: (1) Canarium ovatum (known locally as “pili” or “pilaui”) which is the most important nut-producing species mainly found in the Bicol Region and (2) Canarium luzonicum (known locally as “piling-liitan,” “pisa,” or “basaid”) which is propagated mostly in the Quezon province for its trunk resin.
2.1 Parts and Uses
Being thick due to its hypodermal cells, the shell (endocarp) is commonly used in making native crafts or as a growing medium for orchids and anthuriums. It is also popular for its good charcoal characteristics and can be used as fuel. When processed into activated carbon, it can be used for water purification and as deodorizing, decolorizing, and filtering agents.
The kernel is made up of a brown, papery seed coat (testa) surrounding the embryo which has two white cotyledons . The kernel is the high-priced commodity which is processed mostly for confectioneries. In some parts of the country, the roasted kernels are used in chocolate-making. It is also rich in oil and protein which is suitable for culinary purposes .
3 Bioactive Components of Pili Fruit
3.1 Hydrophilic Bioactive Compounds Present in Skin, Pulp, and Kernel
Six major anthocyanidin-3-O-glucoside commonly found in fruits 
Magenta and crimson
Purple, mauve, blue
The crude skin extract of Canarium ovatum exhibited potential antioxidant activities against DPPH radical with scavenging activity of 89.20% at 1 mg mL−1 (EC50 of 71 μg mL−1) that is comparable to ascorbic acid (EC50 of 66 μg mL−1). Aril-dela Cruz et al.  reported that Canarium ovatum exocarp extract can be a source of functional food colorant with purplish-pink color that can be incorporated in yogurt products with added antioxidant activities.
The defatted Canarium ovatum pulp contains higher levels of total phenolics and condensed tannins (10.1 and 11.1 mg equivalent g−1 sample dry weight, respectively) compared to defatted kernels (3.9 and 0.1 mg equivalent g−1 sample dry weight, respectively). In a study, it was reported that aside from cyanidin, the pulp contains high ferulic acid, a recognized polyphenolic compound to exhibit high antioxidant activity . Besides its antioxidant activity, ferulic acid also exhibits hypoglycemic effects against type 2 diabetes and maintains normal glucose homeostasis [10, 11]. It was also reported that ferulic acid is significantly present in other Canarium species such as C. odontophyllum and C. album and showed high antioxidant and hypoglycemic activities [12, 13].
Arenas and Trinidad  traced the fate of polyphenols present in Canarium ovatum pomace after an in vitro digestibility assay. The simulated digestion of the pomace revealed the changes and bioavailability of polyphenols as it goes through the human intestinal tract. According to the study, condensed tannins and anthocyanins present in Canarium ovatum pomace were released in the gastric and intestinal stages, whereas total phenolics and flavonoids were released after fermentation in the colon. There are studies however that only 10% of the total polyphenols are absorbed in the small intestine. Bulk of these polyphenols are catabolized in the large intestine through bacterial action, and these catabolites are said to be the contributors of the health-promoting effects of polyphenols .
3.2 Lipophilic Bioactive Compounds Present in Pili Oil
Tocopherol content in Canarium ovatum pulp and kernel oil 
Tocopherol content, mg 100 g−1 oil
Carotenoid content in Canarium ovatum pulp and kernel oil 
Carotenoid content, mg 100 g−1 oil
Phytosterol content in Canarium ovatum pulp and kernel oil 
Phytosterol content, mg 100 g−1 oil
Canarium ovatum contains considerable quantities of bioactive compounds with antioxidant properties which are distributed in its fruit parts – the pulp, skin, and kernel. The ethanolic extract of the skin showed high anthocyanin content as evident by its purple to magenta in color. The defatted pulp and kernel showed high levels of total phenolics and condensed tannins with high antioxidant activities against DPPH radicals.
The pulp and kernel contains 20–28% and 60–75% oil with notable presence of unsaponifiable matter consisting of mostly carotenoids, tocopherols, and phytosterols. Most of the tocopherols present in the pulp and kernel oils are δ-tocopherol. Fractionation of the carotenoids revealed high levels of β-carotene, while stigmasterol and campesterol are the dominant phytosterols present in both oils. Studies strongly suggest that these lipophilic bioactive compounds have high antioxidant functionalities in retarding lipid peroxidation in either in vitro or in vivo systems.
Canarium ovatum, being an indigenous tropical tree in the Philippines, can be a source of bioactive compounds with antioxidant activities having high potential for high-value product development. This holds the promise of the beneficial effects of Canarium ovatum as a sustainable source of income for many farmers.
The authors would like to thank the Oils and Fats Laboratory, National Institute of Molecular Biology and Biotechnology (BIOTECH), University of the Philippines Los Baños, College, Laguna.
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