以液相層析質譜法建立靈芝中固醇及三萜類化合物輪廓分析

Abstract

靈芝 (Ganoderma genus) 是一種藥用真菌，因抵抗內源或外源性的氧化壓力，會產生以三萜與固醇等具有生理活性的植化素。不同的靈芝包含赤芝、松杉靈芝及臺灣紫芝會由於不同內生性的酵素在真菌體內反應產生具結構多樣性的靈芝三萜，分為 30 碳骨架的主要型和雙烯型、27 碳的赤芝酸型、24 碳的短鏈型等四種，並在骨架上的不同位置產生羥化、去氫、乙醯化等反應。因為需要有效的分析平台去偵測這些結構複雜的植化素，以作為品質管制依據，本研究使用超高效液相層析串聯高解析軌道阱質譜儀 (Ultra-high performance liquid chromatography coupled to high-resolution Orbitrap mass spectrometry, UHPLC-HRMS/MS) 建立靈芝三萜與固醇化學組成輪廓 (Chemical profile) 之分析平台。本研究所使用的分析平台定性策略包含在層析上化合物因極性不同而產生的分離，包含化合物的氧化取代基的個數、種類、是否發生分子內氫鍵而遮蔽應有的極性及側枝的長短等性質；而後利用高解析一次質譜，針對化合物的不同加成離子、同位素分布及精確分子量進行定性，由此確認碳氫氧個數並確認其潛在的三萜或固醇骨架型式；最後利用化合物在高能碰撞解離 (Higher energy Collision-induced Dissociation, HCD) 後的高解析二次質譜，因依照不同位置取代基的穩定性造成的選擇性斷裂、脫水，利用這些資訊建構整個化合物的結構。依此我們建構了總共可以定性 65 種三萜或固醇化合物的分析平台。包含 29 個 M、D 型靈芝三萜、12 個 L 型靈芝三萜、2 個 S 型靈芝三萜及 5 個固醇，另外也定性了目前文獻尚未報導，然而具有與三萜或固醇相同分子式的潛在 17 種質譜訊號，這些化合物皆能被穩定的相對定量。利用此分析平台進行赤芝、松杉靈芝及臺灣紫芝的樣品分析，可以發現在本平台的分析下，皆發現了相關的固醇訊號。然而在三萜的組成輪廓有很大的區別，台灣紫芝 (G. formosaum) 僅具有微量的靈芝酸 A 及 D；赤芝 (G. lucidum) 具有高量的 27 碳赤芝酸，相對豐度最多的三萜為赤芝酸 A 及 D；松杉靈芝 (G. tsugae) 的三萜廣泛分布，相對豐度最多的主要是30碳的靈芝酸A、12-乙醯氧基靈芝酸F 及靈芝酸H。本研究所利用的UHPLC-HRMS/MS 所建立的分析平台，能有效篩選鑑別靈芝中的三萜與固醇，以利後續定量，並且協助靈芝健康食品工業的原材料篩選以及製程品質管控的應用。

Ganoderma mushroom is a type of medicinal fungus. In order to resist endogenous or exogenous oxidative stress, Ganoderma mushroom would produce bioactive phytochemicals such as Triterpenoids and Steroids. Different Ganoderma mushroom including G. lucidum, G. tsugae and G. formosaum will secrete triterpenoids with structural diversity by different endogenous enzymes in the mushroom. These triterpenoids are divided into four skeleton types: M-type and D-type with 30 carbons skeleton, L-type with 27 carbons skeleton and S-type with 24 carbons. There are also different reactions such as hydroxylation, dehydrogenation and acetylation at different positions on the triterpenoid skeletons. In order to monitor these structurally complex phytochemicals for quality control purpose, this study establish an analysis platform for triterpenoids and steroids chemical profiling analysis based on Ultra-High Performance Liquid Chromatography coupled to high-resolution Orbitrap Mass Spectrometry (UHPLC-HRMS/MS). The qualitative strategy used by this analysis platform included the chromatographic separation of compounds by polarity differences, the exact mass of adducts and isotope-substituted ion, isotope distribution and the fragments of the molecules after Higher energy Collision-induced Dissociation (HCD). In this way, an analysis platform for qualitatively and quantitatively analyzing 65 triterpenoids or steroids was built, including 29 M, D-type triterpenoids, 12 L-type triterpenoids, 2 S-type triterpenoids, 5 steroids and 17 potential signals with triterpenoid and steroid characteristics which had not been reported in the literature. With this analysis platform, ergosterol peroxide were found in G. lucidum, G. tsugae and G. formosaum sample. However, there are a noticeable differences on the triterpenoid chemical profiles: there are only trace Ganoderic acid A and Ganoderic acid D in G. formosaum sample. G. lucidum sample has a large amount of 27-carbon Lucidenic acids, such as Lucidenic acid A and Lucidenic acid D. The triterpenoids in G. tsugae sample are widely distributed, and the most abundant are mainly Ganoderic acid A, 12-Acetoxyganoderic acid F and Ganoderic acid H with 30-carbon triterpenoids. The UHPLC-HRMS/MS analysis platform utilized in this study effectively screens and identifies triterpenoids and steroids in Ganoderma mushrooms. Additionally, this quantitative method serves as a valuable tool for raw material screening and process quality control within the Ganoderma health food industry.