Influence of inhalation exposure to biogenic volatile organic compounds from Syringa oblata flowers on behavior,...

Syringa oblata Lindl. emits a variety of biogenic volatile organic compounds (BVOCs) during full bloom, which forms the key chemical basis for its characteristic floral scent. Species of the genus Syringa have a background of use in traditional medicine and Mongolian medicine, and aromatic plant-derived BVOCs are also relevant to studies on forest bathing, horticultural health, and non-invasive inhalation exposure. However, experimental evidence remains limited regarding the effects of naturally emitted BVOCs from S. oblata flowers and their representative terpene monomers on animal behavior, spatial working memory-related performance, and peripheral hematological parameters.

This study aimed to preliminarily evaluate the effects of inhalation exposure to S. oblata flower-derived BVOCs and representative terpene monomers on locomotor behavior, exploratory behavior, spatial working memory-related performance, and routine hematological parameters in male mice, thereby providing exploratory experimental evidence for the biological assessment of S. oblata flower-derived BVOCs.

BVOCs emitted from S. oblata flowers at full bloom were collected and identified using dynamic headspace sampling combined with gas chromatography-mass spectrometry (GC-MS). Mice were randomly assigned to five groups: a blank control group, an outdoor S. oblata garden exposure group, an indoor α-farnesene exposure group, an indoor limonene exposure group, and an indoor linalool exposure group. The outdoor group was exposed continuously to the S. oblata garden environment for 7 days, whereas the indoor monomer groups received controlled inhalation exposure for 1 h per day for 7 consecutive days. After exposure, body weight change, spontaneous locomotor activity, rearing frequency, defecation output, Y-maze spontaneous alternation, and routine hematological parameters were assessed.

BVOCs emitted from S. oblata flowers mainly included aldehydes, terpenoids, and aromatic compounds. Limonene, α-farnesene, and linalool represented monoterpene hydrocarbons, sesquiterpene hydrocarbons, and oxygenated monoterpene alcohols, respectively. Behavioral assessments showed that S. oblata-related exposure was associated with changes in locomotor and exploratory behaviors. In the indoor α-farnesene, limonene, and linalool exposure groups, spontaneous locomotor activity and rearing behavior decreased to varying degrees. In contrast, Y-maze spontaneous alternation did not show an obvious decrease in any exposure group compared with the control group. Hematological analysis indicated compound-specific changes in peripheral blood parameters. In particular, the limonene exposure group showed a significant decrease in WBC, while RBC, HGB, and HCT showed numerical increases. The α-farnesene group was mainly characterized by reduced spontaneous locomotor activity and rearing behavior, together with a decrease in WBC and a tendency toward increased PLT. The linalool group also exhibited partial behavioral and hematological changes.

Short-term inhalation exposure to S. oblata flower-derived BVOCs and their representative terpene monomers affected locomotor and exploratory behaviors in male mice, while no evident impairment of spatial working memory-related performance was observed. The limonene exposure group showed a significant decrease in WBC, while RBC, HGB, and HCT showed numerical increases without being interpreted as evidence of erythropoiesis. α-farnesene, a relatively less-studied sesquiterpene monomer, may serve as an exploratory candidate for subsequent dose-response and mechanistic studies.