1. Phytoncides are volatile substances released mainly from trees. We studied whether phytoncides can reduce stress responses in stroke-prone spontaneously hypertensive rats (SHRSP). 2. Under the restraint stress, SHRSP exposed to phytoncides showed lower blood pressure than those without the exposure (186.8 +/- 3.9 vs 207.7 +/- 3.4 mmHg, respectively, P<0.01 by Student's t-test). 3. Consistent with the observation above, the plasma concentration of catecholamines under the restraint stress was lower in the phytoncides group than in the control group. 4. Based on these results, we concluded that phytoncides reduced the cardiovascular response to restraint stress in SHRSP.

Phytoncide, nanochemicals extracted from Chamaecyparis obtusa (C. obtusa), is reported to possess many pharmacological activities including immunological stimulating, anti-cancer, antioxidant, and antiinflammatory activities. However, the effect of phytoncide in vascuar diseases, especially on the behavior of vascular smooth muscle cells, has not yet been clearly elucidated. Therefore, in the present study, we investigated the effects of 15 kinds of phytoncide by various extraction conditions from C. obtusa on the proliferation and migration in rat aortic smooth muscle cells (RAoSMCs). First of all, we determined the concentration of each extracts not having cytotoxicity by MTT assay. We observed that the proliferation rate measured using BrdU assay was significantly reduced by supercritical fluid, steam distillation, Me-OH, and hexane extraction fraction in order with higher extent, respectively. Moreover, the treatment of above nanofractions inhibit the migration of RAoSMCs by 40%, 60%, and 30%, respectively, both in 2-D wound healing assay and 3-D boyden chamber assay. Immunoblot revealed that the phosphorylated levels of Akt and ERK were significantly reduced in nanofractions treated RAoSMCs. Taken together, these data suggest that phytoncide extracted from C. obtusa inhibits proliferation and migration in RAoSMCs via the modulation of phosphorylated levels of Akt and ERK. Therefore, phytoncide nanomolecules might be a potential therapeutic approach to prevent or treat atheroscrelosis and restenosis.

To explore the effect of forest bathing on the human immune system, we investigated the effect of phytoncides (wood essential oils) on natural killer (NK) activity and the expression of perforin, granzyme A and granulysin in human NK cells. We used NK-92MI cell, an interleukin-2 independent human NK cell line derived from the NK-92 cell, in the present study. NK-92MI cells express the CD56 surface marker, perforin, granzyme A, and granulysin by flow cytometry and are highly cytotoxic to K562 cells in chromium release assay. Phytoncides significantly increase cytolytic activity of NK-92MI cells in a dose-dependent manner and significantly increase the expression of perforin, granzyme A, and granulysin in the NK-92MI cells. Phytoncides also partially, but significantly, restore the decreased human NK activity and the decreased perforin, granzyme A, and granulysin expression in NK-92MI cells induced by dimethyl 2,2-dichlorovinyl phosphate (DDVP), an organophosphorus pesticide. Pretreatment with phytoncides partially prevents DDVP-induced inhibition of NK activity. Taken together, these data indicate that phytoncides significantly enhance human NK activity and this effect is at least partially mediated by induction of intracellular perforin, granzyme A, and granulysin.