*3.8. Statistical Analysis*

Data are presented as the mean ± SEM from 3–5 independent experiments. Statistical analysis was obtained by using SPSS software (version 25). The difference between groups was evaluated using one-way ANOVA with a post hoc test. The value of *p*-value less than 0.05 (*p* < 0.05) was accepted significant.

#### **4. Conclusions**

This study revealed that the methanol extract of *M. sirikitiae* leaves and isolated lignans, including (−)-phylligenin (**2**) and 3 ,4-*O*-dimethylcedrusin (**6**) possess the antiinflammatory activity by suppressing LPS-induced iNOS and COX-2 synthesis which contribute to a reduction in PGE2 and nitric oxide secretions in RAW 264.7 macrophages. Moreover, 2-(3,4-dimethoxyphenyl)-6-(3,5-dimethoxyphenyl)-3,7-dioxabicyclo[3.3.0] octane (**3**) and mitrephoran (**5**) elicit the anti-inflammatory effects through inhibition of LPS-induced the secretion and synthesis of TNF-α in RAW 264.7 cells. Hence, these findings suggested that several lignans isolated from *M. sirikitiae* leaves might be potential therapeutic candidates for the inhibition and prevention of various inflammatory diseases.

**Supplementary Materials:** The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/molecules27103313/s1. Spectroscopic and physical data of isolated lignans 1–6 from *Mitrephora sirikitiae* Leaf extract.

**Author Contributions:** Conceptualization, N.A. and S.M.; methodology, N.A., S.M., C.L. and K.K.H.; formal analysis, N.A. and S.M.; writing, N.A. and S.M.; supervision, N.A., S.M. and V.R.; project administration, N.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Mahidol University, the Thailand Research Fund (MRG5580047) (to N.A.), the CIF and CNI Grant, Faculty of Science, Mahidol University (to S.M.), and the Center of Excellence for Innovation in Chemistry (PERCH-CIC).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available in supplementary material.

**Acknowledgments:** We would like to acknowledge Narong Nuntasaen for collecting and identification of the plant.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

