Asian Pacific Journal of Tropical Biomedicine

Ethnobotanical review and pharmacological properties of selected medicinal plants in Brunei Darussalam: Litsea elliptica, Dillenia suffruticosa, Dillenia excelsa, Aidia racemosa, Vitex pinnata and Senna alata

3. D. suffruticosa

Locally known as “Simpor bini”, D. suffruticosa is a medium sized tree characterized by its large bright flowers with five thin yellow petals around its white stamen, and dark-pink star-shaped fruits all of which are surrounded by large oval leaves (Figure 2). This plant species typically grows in wastelands, swamps, poor soil, white sands, secondary forests, along roadsides or the edge of forests [11–13]. Its leaves have been traditionally used for different treatments such as to promote wound healing, relieve rheumatism and treat fever while the fruit was claimed to be able to treat cancerous growths [12–16].

The methanolic extract of the roots of this plant have displayed significant antioxidant and cytotoxic activities particularly towards the HeLa cervical cancer cell line [17]. Studies conducted by Armania et al. have indicated that the phenolic content was an important contributor to the high antioxidant activity observed in the methanolic root extract of this plant species [17,18]. Although this extract showed the highest antioxidant and cytotoxic activities in the Hela cell line, it was found that the dichloromethane and ethyl acetate extracts exhibited higher cytotoxicity in the breast cancer cell lines, MCF7, MDA-MB-231, the A549 lung cancer cell line and the HT29 colon cancer cell line [17]. Further mechanistic investigation demonstrated that the plant extract inhibited the proliferation of the HeLa cervical cancer cell line as well as the MCF7 and MDA-MD-231 breast cancer cell lines via the

induction of apoptosis and the G2/M cell cycle arrest [17,18]. An in vivo study conducted by Yazan et al. showed that oral intake of aqueous root extracts have successfully reduced breast cancer induced in rats and also inhibited metastasis of the cancer to the heart [19]. The study further demonstrated that the extract was not toxic at the acute toxicity level up to a high dose of 500 mg/kg, however, mild focal hemorrhage was observed when a dose of 1000 mg/kg of the extract was used for treatment [19]. The cytotoxic activities of this plant species could be attributed to the presence of phytochemicals such as saponins, triterpenes, sterols, and polyphenolic compounds [17,20–26].

Saponins is a collective term for triterpenoid and steroidal glycosides [27], which consists of at least 150 kinds of natural saponins that have displayed significant anti-cancer properties [28]. Moreover, they have been recognized for their ability to reduce cholesterol level in the blood [29]. Dietary and endogenous cholesterols pass through the bile or desquamatedintestinal cells and reach the intestine before they are absorbed into the blood stream [29]. Saponins, being poorly absorbable from the intestine into the blood stream, interact with cholesterols and other sterols, and thus interfere and prevent them from being absorbed into the blood stream [29]. Additionally, saponins have the ability to stimulate the immune system and enhance antibody production [30].

Interestingly, multiple studies have reported reduction in bone loss with diets that are high in saponins [31,32]. One of the many saponins in particular, called asperosaponin VI, was able to induce the differentiation and maturation of osteoblasts and thus increase bone formation via the bone morphogenetic protein-2/p38 synthesis, and activation of the extracellular signal-regulated kinase 1/2 pathway [32].

On the other hand, polyphenols, which include phenolic acids, flavonoids, stilbenes and lignans, have been recognized for their multiple health-benefiting properties [33]. Polyphenols such as resveratrol and quercetin were found to exhibit significant cardio-protective effects by preventing platelet aggregation, disrupting atherosclerotic plaques and inhibiting protein expressions [33]. Other than that, anti-cancer, anti-viral, anti-diabetic, anti-aging and neuro-protective effects were also noted for the phytochemicals in the polyphenol group. They also showed beneficial effects towards asthma, osteoporosis, bone loss, skin damage and mineral absorption in intestines [33].

The phytochemical contents within D. suffruticosa play a significant role in relieving and alleviating illnesses. Perhaps it is a combination of their effects that promote wound healing, relieve rheumatism, and treat fever and cancerous growth traditionally. However, more studies should be performed to fully validate their traditional uses for such diseases.