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Durio zibethinus L. (durian) belongs to the Malvaceae family. It is known as the "King of Tropical Fruit" because of its unique characteristics. The edible part of durian, however, is only about 33% of the fruit while the non-edible parts such as the seed and peels (rinds) are considered as fruit waste responsible for environmental pollution. Thus, the present study was carried out to compare the percentage yields and volatile components from methanol extract and essential oils of the peels of four varieties of durian (Raja Kunyit [D197], Hajah Hasmah [D168], Sultan [D24], and Golden Bun [D13]). The antimicrobial activity of all the extracts and their volatile chemical constituents were also evaluated. Cold maceration was used for the solvent (methanol) extraction. The essential oil extraction was carried out using hydro-distillation and solventfree microwave extraction (SFME) methods. The antimicrobial activity was evaluated against selected microbes using the well diffusion method while the characterization of chemical constituents in the essential oils and crude methanolic extracts was carried out using gas chromatography-mass spectrometry (GC-MS). The highest yields of essential oils were obtained from D24 which were 0.030% and 0.014% from SFME and hydro-distillation extraction, respectively, while the highest and most significant (p < 0.05) yield of methanol extract (8.79%) was obtained from D197. From the GC-MS analysis, butanoic acid was the major compound in the essential oil of durian peels in the four varieties of durians evaluated. Besides butanoic acid, 1-tridecene, 1-pentadecene, and 1-heptadecene were also present in the four varieties. The D168 possesses strong activity against three bacteria (Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa). More novel extraction techniques, bioactivity assays, and characterization are, however, recommended to further explore the potential benefits of durian peels.

Plagioneurin B belongs to acetogenin group has well-established class of compounds. Acetogenin group has attracted worldwide attention in the past few years due their biological abilities as inhibitors for several types of tumour cells. Plagioneurin B was isolated via conventional chromatography and tested for thorough mechanistic apoptosis activity on human ovarian cancer cells (CAOV-3). Its structure was also docked at several possible targets using Autodock tools software. Our findings showed that plagioneurin B successfully inhibits the growth of CAOV-3 cells at IC of 0.62 µM. The existence of apoptotic bodies, cell membrane blebbing and chromatin condensation indicated the hallmark of apoptosis. Increase of Annexin V-FITC bound to phosphatidylserine confirmed the apoptosis induction in the cells. The apoptosis event was triggered through the extrinsic and intrinsic pathways via activation of caspases 8 and 9, respectively. Stimulation of caspase 3 and the presence of DNA ladder suggested downstream apoptotic signalling were initiated. Further confirmation of apoptosis was conducted at the molecular levels where up-regulation in Bax, as well as down-regulation of Bcl-2, Hsp-70 and survivin were observed. Plagioneurin B was also seen to arrest CAOV-3 cells cycle at the G2/M phase. Docking simulation of plagioneurin B with CD95 demonstrated that the high binding affinity and hydrogen bonds formation may explain the capability of plagioneurin B to trigger apoptosis. This study is therefore importance in finding the effective compound that may offer an alternative drug for ovarian cancer treatment.

Honey has been consumed since ancient time due to its nutritional and therapeutic values. Studies showed that honey possesses antioxidant properties which can inhibit oxidation and cell damage in the body. However, the chemical contents and antioxidant properties of honeys are varied, depending on botanical and geographical origins of honey. In this study, we analysed the total phenolic content (TPC), total flavonoid content (TFC), antioxidant properties (DPPH, ABTS, FRAP and TAOC) and volatile profiles of several commercial honeys originated from Malaysia, Turkey, and Yemen. The results showed that sample H4 (Pine honey) from Turkey was the highest in TPC (0.84 µg GAE/mg honey), ABTS (63.15% inhibition) and FRAP (0.45 µg FeSO4 equivalent/mg honey) values, while H2 (Acacia honey) from Malaysia showed the highest values in TFC (0.11 µg quercetin equivalent/mg honey) and DPPH (45.13 mg/mL IC50). Meanwhile, H5 (Marai honey) from Yemen recorded the highest TAOC value (24.14 µg ascorbic acid equivalent/mg honey). Twenty-four volatile compounds were identified using gas chromatography-mass spectrometry (GC-MS), among others are 4H-pyran-4-one, 2,3-dihydro-3,5-dihydroxy-6-methyl, linoleic acid ethyl ester, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, and 2,4-dihydroxy-2,5-dimethyl-3(2H)-furan-3-one which contribute to chemical characteristics of certain honeys. In regards to the TPC, TFC, and antioxidant assays, the honey samples were ranked based on the chemical properties level as follows: H4 (Pine honey) > H2 (Acacia honey) > H7 (Kelulut 2) > H3 (Kelulut 1) > H6 (Sumar honey) > H1 (Tualang honey) > H5 (Marai honey). This finding increases the knowledge of the chemical compositions, volatile compounds, and antioxidant activities of several commercial honeys derived from different botanical and geographical origins.