Analysis of the volatile constituents from Nardostachys jatamansi DC. in combustion by HS-GC-MS and preliminary evaluation on the recycling of its dregs

Objective Nardostachys jatamansi (NJ) is a well-known aromatic plant whose volatile constituents hold considerable pharmacological value; it is primarily used in the form of compound herbal preparations, moxibustion sticks, and essential oil products, exerting sedative and sleep regulatory effects. However, the volatile constituents released upon combustion of NJ, particularly in NJ-containing moxibustion sticks (Wuyan Jiutiao- smokeless moxa-stick and Yaoyong Jiutiao-medicated moxa stick), have not been fully characterized. Herein, we report on the compositional profiling of NJ combustion smoke and a preliminary assessment on the recycling potential of spent NJ extraction residues. Methods The common and distinct volatile constituents in NJ raw herb, residues following methanol ultrasonic extraction and water reflux extraction, and NJ-containing moxibustion sticks were characterized by headspace gas chromatography–mass spectrometry (HS-GC-MS) coupled with controlled combustion. Results A total of 40, 17, 41, and 63 volatile constituents, predominantly sesquiterpenes, were identified from NJ raw herb along with its essential oil and combustion smoke; NJ residues following methanol extraction together with the corresponding combustion smoke and ash; NJ residues following water extraction along with their combustion smoke and ash; and NJ herb combined with the combustion smoke from NJ-containing moxibustion sticks (Wuyan Jiutiao and Yaoyong Jiutiao), respectively. Among them, calarene was the sole constituent identified consistently across all sample matrices, while sesquiterpene alcohols and ketones preferentially accumulated in the NJ essential oil and combustion smoke fractions. A considerable amount of active volatile constituents from NJ, including calarene and β -maaliene, could be detected in combustion smoke of post-extraction residues, particularly after water refluxing extraction. Conclusions The principal volatile constituents of NJ were consistently detected across the combustion smoke of NJ raw herb, post-extraction residues, and NJ-containing moxibustion sticks, suggesting that NJ exerts at least part of its therapeutic activity through combustion. Water reflux extraction residues have the potential to be recycled and reused as raw material for moxibustion stick production. Furthermore, calarene is proposed as a candidate quality marker compound for discriminating NJ from other aromatic herbs employed in moxibustion therapy.