GC-MS and Bioassay-Guided Isolation of Xanthones from <i>Mammea siamensis</i>

Mammea siamensis (Miq.) T. Anders. (Calophyllaceae) plants have long been employed as an active integral composition in Thai traditional medicine. Additionally, phenylcoumarins and triterpenes were reported as major components in phytochemical research. This work explored the various parts of M. siamensis; barks, flowers, twigs, leaves, and young leaves; to determine their bioactive compounds. By using the GC-MS and bioassay guidance, two xanthones, 6-deoxyisojacareubin (1) and 1,5-dihydroxyxanthone (2), together with a mixture of phenylcoumarins, mammea A/AA cyclo D (3) and mammea A/AB cyclo D (4) have been isolated from the methanolic extract of young leaves. Their structures were identified by means of spectroscopic technique and by comparison with literature data. In particular, the current study was the first exposed report of xanthones 1 and 2 from the genus Mammea. Furthermore, compounds 1 and 2 and the methanolic young leaf extract had high antioxidant efficiency on DPPH and ABTS assays. The young leaf extract provided mild toxicity on the brine shrimp lethality test (BSLT) with LC50 value of 93.11 ± 1.37 µg/mL. In addition, the isolated compounds 1 and 2 were non-toxicity in BSLT assay. Therefore, the young leaf extract and the purified constituents 1 and 2 should be further studied and developed for using in pharmaceutical industries

The effect of the circadian and menstrual cycles on cardiovascular and thermoregulatory responses to exercise

Many physiological variables exhibit circadian rhythmicity. The circadian rhythm in core temperature is a well-established and it has been extensively studied during both passive and exercise heat exposure. In females, a circamensal rhythm in core temperature is also present and well established. However, there is little knowledge about whether there is an interaction effect between time of day and phase of menstrual cycle on core temperature and thermoregulatory and cardiovascular responses during and following exercise. The studies in the present thesis were designed to investigate such an interaction effect on the effector responses of the thermoregulation and cardiovascular systems during the exercise and post-exercise periods. The first experiment was designed to examine the time of day effect on thermoregulatory and cardiovascular responses during and following exercise in female subjects. Eight healthy participants completed 30-min exercise at 65%Y02peak at 07:00 and 19:00hr. Core temperature was significantly higher by 0.3, 0.4 and 0.3DC at rest (P=O.OOI), during the exercise (P=O.OOI) and post-exercise (P=0.008) periods in the evening compared to the morning. The second experiment was designed to examine the phases of menstrual cycle on thermoregulatory and cardiovascular responses during and following exercise. Ten healthy participants completed two exercise protocols (65%Y02peak) during the late follicular and luteal phases of the menstrual cycle (day 10-12 and day 20-22 after the onset of menstruation, respectively). Core temperature tended to be higher in the luteal phase compared with the late follicular phase (0.2DC) both at rest (p=O.064) and during exercise (p=0.062), whereas the heat-loss mechanisms were unaffected by menstrual cycle phase. In addition, resting stroke volume and cardiac output was greater in the late follicular phase compared to the luteal phase. The third experiment was designed to explore the interaction effect between time of day and phase of the menstrual cycle on thermoregulatory and cardiovascular responses during the exercise and the post-exercise periods. Ten healthy participants completed four exercise protocol (65% Y02peak); two exercise protocols in the morning of the late follicular and luteal phases, and two exercise protocols in the evening of the late follicular and luteal phases. Core temperature was higher in the evening of both phases of the menstrual cycle during exercise (p=O.OOI) and the post-exercise periods (p=O.003). There was an interaction effect between times of day and phase of the menstrual cycle on mean skin temperature during the exercise (p=0.048) and the post-exercise periods (p=0.006), a lower mean skin temperature in the evening compared with the morning during the late follicular phase and higher in the evening than in the morning in the luteal phase. However, there was no interaction of times of day and phase of menstrual cycle for other thermoregulatory and cardiovascular parameters measured. The results in the thesis indicate that temperature regulation is set around higher values in the evening and late luteal phase of the cycle, but that these changes are likely independent of each other. Future work, should more systematically investigate these responses, collecting data at more times of day and phases of the cycle.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Cytotoxic, Antitopoisomerase IIα, and Anti-HIV‑1 Activities of Triterpenoids Isolated from Leaves and Twigs of <i>Gardenia carinata</i>

Eight new cycloartane triterpenoids (<b>1</b>–<b>8</b>), named carinatins A–H, and the known compounds secaubryolide (<b>9</b>) and dikamaliartane D (<b>10</b>) were isolated from the leaves and twigs of <i>Gardenia carinata</i>. Their structures were determined on the basis of spectroscopic methods. Cytotoxic, antitopoisomerase IIα, and anti-HIV-1 activities of compounds <b>1</b>–<b>7</b>, <b>9</b>, and <b>10</b> were investigated

Oleanolic Acid Loaded PEGylated PLA and PLGA Nanoparticles with Enhanced Cytotoxic Activity against Cancer Cells

Oleanolic acid (OA) is a natural triterpenoid with anticancer properties, but its hydrophobic nature and poor aqueous solubility pose challenges in pharmaceutical formulation development. The present study aimed at developing OA-loaded mPEG–PLGA or mPEG–PLA nanoparticles (NPs) to improve the delivery of OA. The NPs were prepared by nanoprecipitation, and their physicochemical properties were characterized. The OA encapsulation efficiency of the NPs was between 40 and 75%. The size of the OA-loaded NPs was around 200–250 nm, which fell within the range required for tumor targeting by means of the enhanced permeability and retention (EPR) effect, and the negatively charged NPs remained physically stable for over 20 weeks with no aggregation observed. The OA-loaded NPs produced significant cytotoxic effects through apoptosis in cancer cell lines. Overall, the OA-loaded mPEG–PLGA NPs and mPEG–PLA NPs shared similar physicochemical properties. The former, especially the OA-loaded mPEG-P(D,L)LGA NPs, were more cytotoxic to cancer cells and therefore were more efficient for OA delivery