**2. Identification of phytochemicals in** *C. inophyllum* **leaves**

### **2.1 Xanthones**

Xanthones are polyphenol components in nature with molecular formula C13H8O2. They consist of bonding of two benzene rings connected by a carbonyl group and one oxygen. These conjugated ring systems inhibit the free rotation carbon bond. Xanthones have a basic framework consisting of 13 carbon atoms that make up the composition of C6-C1-C6 (**Figure 2**).

Xanthones are compounds with the basic framework of two phenyls connected by bridges carbonyl and oxygen (ether). Their biosynthesis is not known clearly but allegedly still in close contact with the biosynthesis of flavonoids and stilbenoid. It can be seen from the type of oxygenation and two types of aromatic rings which are derived from the shikimate (shikimic acid) and the acetatemalonate pathways.

Xanthones compound that was isolated from *C. inophyllum* plants, there are prenylated and some are not prenylated. Most xanthone compounds isolated from these plants showed a characteristic, one of which is a hydroxy group at C1. The possible oxygenation position is shown in **Figure 2**.

Xanthones are known to have a variety of bioactive properties, notably the ability of antioxidants as can be seen in **Figure 3**. Mangosteen xanthones were isolated from *Garcinia mangostana* found against free radicals and prevent oxidative damage of low-density lipoprotein [16]. Moreover, isolated xanthones from mangosteen also can inhibit HL60 leukemia cells [17]. Also, α-mangosteen extracted from *G. mangostana* L. has antibacterial activity against vancomycin-resistant enterococci (VRE) and methicillin-resistant *Staphylococcus aureus* (MRSA) [18].

Various xanthone compounds can be isolated from *C. inophyllum* leaves, such as caloxanthone A, caloxanthone B, caloxanthone C, maclura xanthones, inoxanthone, calophynic acid, 3,4-dihydroxy xanthones [4, 12, 19], brasilixanthone B, buchanaxanthone [20], inophyxanthone A, pancixanthone A, gerontoxanthone B, jacareubin, pyranojacaereubin, 2-hydroxy xanthone, 4-hydroxyxanthone, 1,3,5-trihydroxy-2-methoxyxanthone, and xanthones [21, 22].
