鹰木香木材解剖学、生理特性及挥发性成分研究

Research on the Wood Anatomy, Physiological Properties, and Volatile Constituents of Aetoxylon sympetalum (Steenis & Domke) Airy Shaw

摘要: 本文报道了鹰木香[Aetoxylon sympetalum (Steenis & Domke) Airy Shaw]木材的生理特性、解剖结构及挥发性成分。采用《无疵小试样木材物理学性质试验方法 第5部分：密度测定》(GB/T 1927.5-2021)、《木材pH值的测定》(GB/T 6043-2009)、蒽酮比色法、考马斯亮蓝法、木材解剖学方法和气相色谱–质谱(GC-MS)法分别测定了其基本密度、pH值、淀粉和可溶性糖含量、可溶性蛋白含量、解剖结构及挥发性成分，为其植物保护、木材识别及开发利用等方面研究提供科学依据。结果表明：1) 鹰木香的木材很硬，基本密度为1.956 g/cm³，水试发现其沉水。2) 鹰木香的木材pH为5.95，呈弱酸性；淀粉含量为69.403 mg/g；可溶性糖含量为34.232 mg/g；可溶性蛋白含量为0.086 mg/g。3) 鹰木香与棱柱木属(Gonystylus Teijsm. & Binn.)木材解剖构造相近，但而与沉香属(Aquilaria Lam.)木材的区别较大：① 前二者均无内涵韧皮部，而后者则具岛屿状内涵韧皮部；② 前二者以单管孔为主，而后者以径列复管孔为主；③ 前二者的轴向薄壁组织呈翼状、聚翼状及带状，而后者呈傍管状，并在内涵韧皮部周围形成厚鞘；④ 前二者的木射线类型以异形或同形单列为主，而后者以异形III型为主。鹰木香和棱柱木属木材的差异甚小，主要在于前者的径列复管孔(2~3个)普遍，导管分子长度较长(570~620 μm)，木射线异形单列为主，晶体以菱形为主，稀棱柱形；而后者则偶见径列复管孔(2个)，导管分子长度较短(310~450 μm)，木射线同形单列为主，晶体呈棱柱形或柱状。4) GC-MS分析结果表明：共有28种倍半萜类成分和1种烯烃类化合物，其中有10种倍半萜类与沉香属所结沉香共有。与邦加棱柱木(G. bancanus)的精油挥发性成分十分相近，二者的主要成分均为桉叶油醇异构体(α-, β-, γ-) (相对百分含量 > 80%)，又以γ-桉叶油醇最高(相对百分含量 > 50%)。另外，文章还根据桉叶油醇的不同构型，推测了其香味类型与行业内通常描述的“淡淡的苔泥清香、柔致的胡椒辛香和优雅的花香”较吻合。桉叶油醇异构体(α-, β-, γ-)具有抗肿瘤、抗菌、抗高血压等多种生物活性。鹰木香木材具有作为天然香料、药用植物精油、食品添加剂以及保鲜剂等方面的开发利用价值和应用潜质。

Abstract: This research reports on the physiological properties, anatomical structure, and volatile components of the wood from Aetoxylon sympetalum (Steenis & Domke) Airy Shaw. The basic density, pH value, starch and soluble sugar content, soluble protein content, anatomical structure, and volatile components of the wood were determined by using “Test methods for physical and mechanical properties of small clear wood specimens—Part 5: Determination of density” (GB/T 1927.5-2021), “Determination of pH of Wood” (GB/T 6043-2009), Anthrone Colorimetric method, Coomassie Brilliant Blue method, wood anatomical method, and GC-MS method, to establish a scientific foundation for its plant protection, wood identification, development and utilization. The results indicated that: 1) The wood of A. sympetalum is very hard, with a basic density of 1.956 g/cm³. Water tests have found that it sinks into water. 2) The pH value of the wood of A. sympetalum is 5.95, which is weakly acidic. The starch content is 69.403 mg/g; The soluble sugar content is 34.232 mg/g; The soluble protein content is 0.086 mg/g. 3) The wood of A. sympetalum has similar anatomical structures to the wood of the Gonystylus genus, but differs greatly from the wood of the Aquilaria genus: ① The former two have no included phloem, while the latter have island shaped included phloem; ② The former two are mainly single pores, while the latter are mainly radial multiple pores; ③ The axial parenchyma of the former two are winged-aliform, cluster winged-aliform, and band shaped, while the latter is paratracheal and forms thick sheath around the included phloem; ④ The wood ray types of the former two are mainly heteromorphic or homomorphic uniseriate, while the latter is mainly heteromorphic type III. The difference between the wood of the Aetoxylon and Gonystylus is very samall, mainly due to the former has a common number of radial multiple pore (2~3), longer vessel elements length (570~620 μm), mainly heterogeneous uniseriate wood rays, and rhombic mainly, prismatic sparsely crystals; The latter has occasional radial multiple pore (2), shorter vessel elements length (310~450 μm), mainly homogeneous uniseriate wood rays, and prismatic or columnar crystals. 4) The GC-MS analysis results indicated that there are a total of 28 sesquiterpenes and 1 alkene compound, among which 10 sesquiterpenes are shared with Aquilaria agarwood. The volatile components of the essential oil are very similar to those of Gonystylus bancanus wood, with the main components of eudesmol isomers (α-, β-, γ-) (relative percentage content > 80%), with the highest content of γ-eudesmol (relative percentage content > 50%). In addition, based on the different configurations of eudesmol, this research speculates that its aroma type is more consistent with the industry’s usual descriptions of “light moss and mud fragrance, soft pepper spice fragrance, and elegant floral fragrance”. Eudesmol isomers (α-, β-, γ-) have various biological activities such as antitumor, antimicrobial, and antihypertensive properties. The wood of Aetoxylon sympetalum has development and utilization value and application potential in natural fragrances, medicinal plant essential oil, food additives, and preservatives.