With strong antimicrobial properties, citral has been repeatedly reported to be the dominant component of lemongrass essential oil. Here, we report on a comparison of the antimicrobial and anticancer activity of citral and lemongrass essential oil. The lemongrass essential oil was prepared by the vacuum distillation of fresh Cymbopogon leaves, with a yield of 0.5% (w/w). Citral content was measured by gas chromatography/high-resolution mass spectrometry (GC-HRMS) and determined to be 63%. Antimicrobial activity was tested by the broth dilution method, showing strong activity against all tested bacteria and fungi. Citral was up to 100 times more active than the lemongrass essential oil. Similarly, both citral and essential oils inhibited bacterial communication and adhesion during P. aeruginosa and S. aureus biofilm formation; however, the biofilm prevention activity of citral was significantly higher. Both the essential oil and citral disrupted the maturated P. aeruginosa biofilm with the IC50 7.3 ± 0.4 and 0.1 ± 0.01 mL/L, respectively. Although it may seem that the citral is the main biologically active compound of lemongrass essential oil and the accompanying components have instead antagonistic effects, we determined that the lemongrass essential oil-sensitized methicillin-resistant S. aureus (MRSA) and doxorubicin-resistant ovarian carcinoma cells and that this activity was not caused by citral. A 1 mL/L dose of oil-sensitized MRSA to methicillin up to 9.6 times and a dose of 10 µL/L-sensitized ovarian carcinoma to doxorubicin up to 1.8 times. The mode of multidrug resistance modulation could be due to P-glycoprotein efflux pump inhibition. Therefore, the natural mixture of compounds present in the lemongrass essential oil provides beneficial effects and its direct use may be preferred to its use as a template for citral isolation.

The course of senescence in the first leaves of light-grown Arena seedlings when attached to the plant has been compared with that previously studied in detached leaves and leaf segments. Proteolysis in the leaf, whether attached or detached, is accompanied by markedly polar basipetal transport of amino acids. This polar transport can be superimposed on the known transport of amino acids towards a locally applied cytokinin. In the intact plant, it results in a strong movement into the roots. The reducing sugars, which are set free in senescence, do not participate appreciably in this polar transport phenomenon.If cytokinin is applied directly to the roots, then, if the plants are 7 days old, it becomes transported upward into the basal parts of the leaf and there delays the senescence process. How. ever, if the plants are 10 days old, a "reverse Mothes effect" occurs, in which senescence of the leaf is actually promoted and part of the amino acids transported into the roots is synthesized into root protein.The course of the rapid senescence in isolated first leaves and leaf segments of Avena sativa placed in the dark has been reported in detail (7, 10, 13) and can be summarized briefly as follows. The proteolysis and yellowing, which are well known to occur, begin within 24 hr, the proteolysis being detectable after 6 hr; both are prevented by cytokinins or by cycloheximide, but promoted by L-serine and L-cysteine. There is a large (more than 200%) increase in 02 consumption lasting 4 to 5 days, and ascribed partly to the respirable substrates, i.e. the amino acids and reducing sugars, which are liberated, but in larger part to some type of uncoupling between respiration and phosphorylation. This respiratory increase, like the proteolysis, is totally prevented by kinetin or other cytokinins, which even lower the respiration somewhat below the initial level. There is a marked increase in RNase also, which had been observed earlier (12, 15); this increase is largely prevented by kinetin, and kinetin's action is again antagonized by serine (10).The amino acids and sugars liberated during senescence accumulate in the detached leaf, but presumably in the intact

A new flavonoid glycoside, globlin A (1), and eleven known compounds were isolated from methanolic extracts of the leaves of Glochidion obliquum. The structure of this new compound was established with a combination of 2D NMR techniques (COSY, NOESY, HMQC and HMBC) and HR-ESI-MS analyses. Chemical structures of the other known compounds were identified by comparison of their spectroscopic and physical data with those reported in the literature. Some of the isolates were examined for their bioactivities. Among the tested compounds, rotundic acid (4) displayed significant cytotoxicity and anti-inflammatory activities.

No abstract

This study updates the status and conservation of the Endangered Asian elephant Elephas maximus in Cat Tien National Park, Vietnam. Line transect indirect surveys, block surveys for elephant signs, village surveys of elephant-human conflict incidents, guard-post surveys for records of sightings, and surveys of elephant food plants were undertaken during the dry and wet seasons of 2001. A minimum of 11 elephants and a maximum of 15-17 elephants was estimated for c. 500 km 2 of the Park and its vicinity. The elephants are largely confined to the southern boundary of the Park and make extensive use of the adjoining La Nga State Forest Enterprises. During the dry season the elephants depend on at least 26 species of wild and cultivated plants, chiefly the fruits of cashew. Most of the villages surveyed reported some elephant-human conflict. Two adult male elephants seem to cover a large area to raid crops, whereas the family groups restrict themselves to a few villages; overall, the conflict is not serious. Since 2001 there have been no reports of any deaths or births of elephants in the Park. We make recommendations for habitat protection and management, increasing the viability of the small population, reducing elephant-human conflicts, and improving the chances of survival of the declining elephants of this Park. The Government has now approved an Action Plan for Urgent Conservation Areas in Vietnam that calls for the establishment of three elephant conservation areas in the country, including Cat Tien National Park.