The wood of Michelia macclurei Dandy (MD) is an excellent material that is widely used in the furniture, handicraft, and construction industries. However, less research has been conducted on the chemical composition and biological activity of heartwood, which is the main valuable part of the wood. This study aimed to investigate the chemical composition and biological activities of the heartwood of Michelia macclurei Dandy (MDHW) and to confirm the active ingredients. Triple quadrupole gas chromatography–mass spectrometry (GC-MS) was used to characterize the volatile components of MDHW, while ultra-performance liquid chromatography–mass spectrometry was used to analyze the non-volatile components (UPLC-MS). The total reducing power, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assays, acetylcholinesterase and α-glucosidase inhibition assays, and an antimicrobial test of 4 gram bacteria were used to describe the in vitro bioactivities. The GC-MS analysis showed that the volatile components of MDHW were mainly fatty compounds and terpenoids, with sesquiterpenes and their derivatives dominating the terpene composition. β-elemene was the main terpene component in the steam distillation (11.88%) and ultrasonic extraction (8.2%) methods. A total of 67 compounds, comprising 45 alkaloids, 9 flavonoids, 6 lignans, and others, were found by UPLC-MS analysis. The primary structural kinds of the non-volatile components were 35 isoquinoline alkaloids. Alkaloids were the predominant active constituent in all MDHW extracts, including crude extracts, alkaloid fractions, and non-alkaloid fractions. These extracts all demonstrate some biological effects in terms of antioxidant, enzyme inhibition, and bacterial inhibition. The findings of this study show that MDHW is abundant in chemical structure types, has great bioactivity assessment, and has the potential to be used to create natural antioxidants, products that postpone Alzheimer’s disease and lower blood sugar levels and antibacterial agents.

A sapwood tree is a species in which the sapwood does not differ significantly from the heartwood and cannot be classified by shades of color. It is generally accepted that heartwood has a higher economic value than sapwood, but most of the studies related to heartwood formation have focused on heartwood trees, with less research on sapwood trees. In this paper, we take the sapwood tree Schima superba as the research object and analyze the physiological and biochemical changes in the process of heartwood formation by studying the anatomical structure of parenchyma cells, and then further explore the main categories of metabolites and compositional changes. The results showed that during heartwood formation, the parenchyma cells become inactive and the nucleus disappears, while at the same time, the storage substance starch is gradually degraded under the action of enzymes and transformed into secondary metabolites, which include terpenoids, phenols and alkaloids. The accumulation of white and colorless compounds in large quantities in the heartwood, which has some effect on the heartwood color, is an important reason why the heartwood in Schima superba shows normal formation but no difference in color from the sapwood. This study fills a gap in the mechanism of heartwood formation in sapwood trees.