目的

针对乳香质量等级标准缺失的现状，本研究整合传统中医药理论和现代分析技术，构建基于“感官-化学-效应”的综合质量评价体系。在区分样品产地的基础上划分乳香质量等级，并验证其合理性，为建立科学规范的乳香质量等级标准提供依据。

方法

共收集到89批乳香样品，通过文献和市场调研确定可量化的外观性状指标。以《中华人民共和国药典》为指导对样品产地（索马里、埃塞俄比亚、苏丹）进行确认并筛选合格样品。通过电子感官技术量化颜色和气味两个性状指标，使用UHPLC-PDA方法测定七个萜类成分含量，整合外观性状与化学指标划分乳香质量等级。在此基础上，采用基于UHPLC-MS和GC-MS技术的非靶向代谢组学技术全面表征乳香代谢物，筛选不同等级乳香间非挥发性及挥发性差异标志物。最后，构建LPS诱导的RAW264.7细胞炎症模型，对比不同等级乳香95%乙醇提取物的抗炎活性，验证质量分级的合理性。

结果

（1）颜色、气味、含杂率及挥发油含量是评价乳香质量的关键性状指标。

（2）89批乳香样品中，2批鉴定所得产地信息与市场提供不一致，8批不符合药典标准，包括1批杂质超标和7批挥发油含量不足。

（3）色度值测定结果表明，81批乳香颜色有显著差异。K-means聚类可将81批乳香分为淡黄色、黄色和黄褐色三类。不同产地的乳香中，索马里乳香颜色最浅，偏向淡黄色。而电子鼻在不同批次样品的识别中表现不佳，无法对其进行区分。

（4）基于UHPLC-PDA法的七种萜类化合物的定量分析显示，其含量在不同产地和颜色类别的乳香中存在显著差异。淡黄色样品中化合物总量均值最高，黄褐色最低。不同产地样品中，苏丹乳香化合物总量均值最高，且聚类分析可将埃塞俄比亚和苏丹乳香归为一类，索马里乳香单独聚类。

（5）结合外观性状及化学指标将不同产地的乳香各自划分为三个质量等级。索马里乳香中一级样品占比最小、二级居中、三级最多。埃塞俄比亚和苏丹乳香一级样品占比最小、二级样品占比最大，三级居中。

（6）非靶向代谢组学分析表明，差异代谢物主要包括脂质类、有机酸类、有机氧化合物及萜类化合物。不同质量等级的索马里、埃塞俄比亚和苏丹乳香间分别筛选得到69、26、55个挥发性及10、37、37个非挥发性差异标志物。

（7）基于LPS诱导的RAW264.7细胞炎症模型的抗炎药效研究表明，高质量等级的乳香抗炎效果均优于低等级乳香，即本研究对乳香质量等级的划分科学合理。

结论

本研究通过多维度分析研究，构建了基于“感官-化学-效应”的乳香质量评价方法，为乳香质量等级标准的建立提供重要依据。

Objective

In response to the lack of quality grading standards for frankincense, this study integrates traditional Chinese medicine theories with modern analytical techniques to comprehensively establish and validate the quality grades of frankincense from different origins based on a “sensory-component-effect” approach, providing a scientific basis for the development of standardized and normative quality grading criteria for frankincense.

Methods

A total of 89 batches of frankincense samples were collected from four major Chinese herbal medicine markets (Anguo, Bozhou, Lotus Pond, Yulin) and imported medicinal material companies. Quantifiable indicators of appearance characteristics were determined through literature review and market investigation. The Chinese Pharmacopoeia was used as a guide to confirm the classification of the origin of the samples (Somalia, Ethiopia, and Sudan), and to exclude unqualified samples according to the regulations on impurities and volatile oil content. Appearance traits (color and odor) were quantified using electronic sensory technology, and seven terpenoid components were simultaneously determined by UHPLC-PDA. A quality grading system for frankincense was established by integrating these appearance characteristics with chemical indicators. Subsequently, untargeted metabolomics based on UHPLC-MS and GC-MS was used to screen the non-volatile and volatile difference markers among different grades of frankincense. Finally, an LPS-induced RAW264.7 cell inflammation model was established to comparatively evaluate the anti-inflammatory activities of 95% ethanol extracts of frankincense of different quality grades, thereby validating the rationality of the established classification system.

Results

(1) Literature and market research revealed that color, odor, impurity content, and volatile oil content are key traits for frankincense quality.

(2) Among the 89 collected batches of frankincense samples, the identified origin of batches R13 and R14 was inconsistent with the information provided by the market. Additionally, 8 batches did not meet the Chinese Pharmacopoeia standards, including 1 batch with excessive impurities and 7 batches with insufficient volatile oil content.

(3) The colorimetric analysis of frankincense powder demonstrated significant chromatic variation among the 81 batches. K-means clustering classified these samples into three categories: pale yellow, intermediate yellow, and yellowish-brown. The color of frankincense powder varies greatly among different regions, with Somali frankincense having the lightest color, leaning towards a light yellow. However, electronic nose detection exhibited limited discriminative capability and failed to differentiate between batches effectively.

(4) The quantitative analysis of seven terpenoids based on UHPLC-PDA method revealed significant differences in content among frankincense samples from different origins and color categories. The average total content was highest in pale yellow samples and lowest in yellow-brown samples. Among samples from different regions, Sudanese frankincense exhibited the highest content. Furthermore, cluster analysis grouped Ethiopian and Sudanese frankincense together, while Somali frankincense formed a separate cluster.

(5) Based on appearance traits and chemical indicators, frankincense samples from different origins were classified into three quality grades, respectively. In Somali frankincense, Grade 1 had the smallest proportion, Grade 2 was intermediate, and Grade 3 was the most abundant. For Ethiopian and Sudanese frankincense, Grade 1 also had the smallest proportion, Grade 2 had the largest proportion, and Grade 3 was intermediate.

(6) Untargeted metabolomics analysis identified four classes of common differential metabolites: lipids, organic acids, organic oxygen compounds, and terpenoids. A total of 69, 26, and 55 volatile differential markers and 10, 37, and 37 non-volatile differential markers were screened from frankincense of different quality grades from Somalia, Ethiopia, and Sudan, respectively.

(7) The anti-inflammatory efficacy of frankincense was assessed using an LPS-induced RAW264.7 macrophage inflammation model. The results show that higher-quality frankincense exhibits superior anti-inflammatory effects compared to lower-quality samples, indicating that the classification of frankincense quality grades in this study is scientifically reasonable.

Conclusion

This study established and validated a comprehensive grading system for frankincense through multidimensional analyses encompassing electronic sensory evaluation, active component characterization, and biological effect assessment, providing an important basis for establishing standardized quality grading criteria for frankincense.