Catunaregam tomentosa (Blume ex DC) Tirveng is commonly known as Khet in Thailand and Bisa Ular or Badang in Malaysia. The tree is widely distributed in the north-east region of Thailand while in Malaysia the tree usually grows in the open waterfront area at Terengganu. This plant belongs to the Rubiaceae family, and the genus catunaregam has interesting pharmacological activities such as anti-inflammatory, antispasmodic, antidysenteric, antifertility and immunomodulatory. In this study, the leaves were extracted using dichloromethane, ethyl acetate and ethanol. Total phenolic was determined by Folin-Ciocalteau method while total flavonoid was determined by the aluminium chloride calorimetric method. Meanwhile, its antioxidant activity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The ethanolic extract was found to have the highest percentages of phenolic and flavonoid content. Interestingly, ethanolic extract also demonstrated strong DPPH scavenging activity with IC50 at 20.07 ± 0.51µg/mL.

Catunaregam tomentosa is a plant from Rubiaceae family that is used in traditional medicine for the treatment of stomatitis and ulcers due to bacterial infections. Besides, it also helps in the treatment of oliguria and dysuria. Indiscriminate use of commercial antibacterial medicines had led to the search for novel antibacterial drugs. Since for ages medicinal plants have been used to treat bacterial infection, so they can be excellent sources of the novel antibacterial drug. To evaluate the scientific basis of the use of plant, antibacterial activity leaves extract of C.tomentosa was investigated against selected Gram-positive and Gram-negative bacteria. The study also investigated the effect of pH on its antibacterial activity. Antibacterial activity of the plant extracts was evaluated against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa by using the disc diffusion method at 100mg/mL concentration. Extracts of C. tomentosa inhibit the activity of S. aureus but do not inhibit the activity of Gram-negative bacteria. Minimum inhibitory concentration (MIC) was also determined against S. aureus at concentration 100, 50, 25, 12.5, 6, 3, 1.5, 0.75 and 0.395mg/mL and 3mg/mL were the MIC value. Evaluation on the effect of different pH on antibacterial activity of plant extracts shows that the activity of the plant extracts does not affect when treated with acidic pH but increased at alkaline pH. Based on the present finding, C. tomentosa leaves extract have the potential to be a viable candidate in the discovery of a natural antibacterial agent against S. aureus infections. This study provides scientific knowledge to further determine the antibacterial values of C. tomentosa extracts.

Aquilaria malaccensis, also known as “Pokok Karas” in Malaysia, has various benefits and widely used in Chinese herbal medicines. Natural products such as medicinal plant have been found to be effective anti-cancer agents, killing cancer cells with fewer side effects than chemotherapy. Therefore, the purpose of this study was to evaluate the cytotoxic activities of ethanolic extract of A. malaccensis on the human chronic myeloid leukaemia K-562 cell line. In this study, cytotoxic activities of ethanolic extract of A. malaccensis leaves on K-562 cells was determined by using (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) (MTT) assay. K-562 cells were treated with 70% ethanolic extracts and incubated for 24, 48 and 72 hours. The half-maximal inhibitory concentration (IC50) of ethanolic extract of A. malaccensis leaves was observed at 72 hours of incubation; 90 µg/mL for 70% ethanolic extract. Moreover, the morphological changes of K-562 cells were observed by using acridine orange/ propidium iodide (AO/PI) dual staining assay. The results showed that the ethanolic extract of A. malaccensis leaves induced K-562 cells into apoptotic cell death mode manner. This finding suggested that the ethanolic extract of A. malaccensis has the potential to become an anti-cancer agent for chronic myeloid leukaemia K-562 cell line.