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Here we report for the first time the entire 13 C-NMR spectral assignments of 119 (out of 127) triterpenoids from the oleo-gum resins of the medicinally important genus Boswellia, which includes the culturally highly valuable Frankincense species. The complete 13 C-NMR resonances of these triterpenoids isolated between 1998 and 2024 and their biological activities are presented. 13 C-NMR spectroscopy is a highly powerful tool for the characterization of these bioactive natural products. The compounds are arranged according to their skeletons, i.e., ursane, oleanane, lupane, dammarane, and tirucallane triterpenes. This review will be a future reference for the identification of these compounds, which have key medicinal properties in the areas of cytotoxicity and inflammation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This review is not intended to describe the triterpenes isolated from the Boswellia genus, since this information has been covered elsewhere. Instead, the aim is to provide insights into the biosynthesis of triterpenes in Boswellia. This genus, which has 24 species, displays fascinating structural diversity and produces a number of medicinally important triterpenes, particularly boswellic acids. Over 300 volatile components have been reported in the essential oil of Boswellia, and more than 100 diterpenes and triterpenes have been isolated from this genus. Given that no triterpene biosynthetic enzymes have yet been isolated from any members of the Boswellia genus, this review will cover the likely biosynthetic pathways as inferred from structures in nature and the probable types of biosynthetic enzymes based on knowledge of triterpene biosynthesis in other plant species. It highlights the importance of frankincense and the factors and threats affecting its production. It covers triterpene biosynthesis in the genus Boswellia, including dammaranes, tirucallic acids, lupanes, oleananes, ursanes and boswellic acids. Strategies for elucidating triterpene biosynthetic pathways in Boswellia are considered. Furthermore, the possible mechanisms behind wound-induced resin synthesis by the tree and related gene expression profiling are covered. In addition, the influence of the environment and the genotype on the biosynthesis of resin and on variations in the compositions and types of resins will also be reviewed., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The distribution and biosynthesis of boswellic acids (BAs) is scarce in current literature. Present study aims to elucidate the BAs biosynthetic and its diversity in the resins of Boswellia sacra and Boswellia papyrifera. Results revealed the isolation of new (3β, 11β-dihydroxy BA) and recently known (as new source, β-boswellic aldehyde) precursors from B. sacra resin along with α-amyrin. Following this, a detailed nomenclature of BAs was elucidated. The quantification and distribution of amyrins (3-epi-α-amyrin, β-amyrin and α-amyrin) and BAs in different Boswellia resins showed highest amyrin and BAs in B. sacra as compared with B. serrata and B. papyrifera. Distribution of BAs significantly varied in the resin of B. sacra collected from dry mountains than coastal trees. In B. sacra, high content of α-amyrin was found in the roots but it lacked β-amyrin and BAs. The leaf part showed traces of β-ABA and AKBA but was deficient in amyrins. This was further confirmed by lack of transcript accumulation of amyrin-related biosynthesis gene in leaf part. In contrast, the stem showed presence of all six BAs which are attributed to existence of resin-secretory canals. In conclusion, the boswellic acids are genus-specific chemical constituents for Boswellia species albeit the variation of the amounts among different Boswellia species and grades., Competing Interests: The authors have declared that no competing interests exist.

Introduction: Incensole can be considered as a biomarker for Boswellia species which is a diterpene that has received remarkable pharmacological interest recently due to its potent anti-inflammatory and anti-depressant activity., Objective: Near-infrared (NIR) spectroscopy coupled with PLSR (partial least squares regression) as a robust, rapid and alternative method was used to quantify the content of incensole in three species namely B. papyrifera, B. sacra and B. serrata and cross-validated by high-performance liquid chromatography (HPLC)., Materials and Methods: NIR spectrophotometer was used for the quantification of incensole standards and Boswellia species in absorption mode in the wavelength range between 700 and 2500 nm. A PLSR model was built from the obtained spectral data using 70% of the incensole working standard solutions (training set), ranging from 0.5 to 100 ppm. The PLSR model obtained has a R 2 value of 98% with a correlationship of 0.99 and a good prediction with root mean square error for prediction (RMSEP) value of 3.2%., Results: The results indicated that the methanol (MeOH) extract of B. papyrifera resin has the highest concentration of incensole (18.4%) followed by n-hexane (13.5%) and ethyl acetate (3.6%) while trace amounts was detected in the fractions of B. sacra and no incensole was detected in the fractions of B. serrata., Conclusion: The findings are in total agreement with the HPLC analysis suggesting that NIR spectroscopy coupled with PLSR is a robust, rapid and non-destructive alternate method for the quantification of incensole in B. papyrifera. Copyright © 2018 John Wiley & Sons, Ltd., (Copyright © 2018 John Wiley & Sons, Ltd.)

Introduction: 3-O-Acetyl-11-keto-β-boswellic acid (AKBA), one of the pentacyclic triterpenoids, is the main biologically active constituent in the resin of Boswellia sacra and has received significant pharmacological interest in recent years., Objective: It was aimed to develop a robust method to quantify the AKBA content in methanolic extracts of different parts of B. sacra plants and in various fractions of its resin exudates through near-infrared spectroscopy (NIRS) coupled with partial least squares regression (PLSR)., Material and Methods: The near-infrared (NIR) spectra were used to measure the AKBA standards and B. sacra samples at a wavelength range between 700 and 2500 nm in absorption mode. A PLSR model was built from the obtained spectral data using 70% of the AKBA working standard solutions (training set), ranging from 0.1 ppm to 100 ppm. The final PLSR showed a R 2 value of 99% with a root mean square error of cross-validation (RMSECV) value of 0.39% and a R 2 value of 99%., Results: The results showed that a 50% CHCl 3 /n-hexane sub-fraction has the highest concentration of AKBA (14.8%), followed by 55% CHCl 3 /n-hexane (13.6%), and 40% CHCl 3 /n-hexane (6.1%)., Conclusion: As the results achieved with the proposed NIRS methodology are in close agreement to the results of AKBA analysis using HPLC, we suggest that our proposed NIRS method is a fast alternative and non-destructive method for the analysis of AKBA in different samples of B. sacra. Copyright © 2017 John Wiley & Sons, Ltd., (Copyright © 2017 John Wiley & Sons, Ltd.)

In the present study, for the first time, NIR spectroscopy coupled with PLS regression as a rapid and alternative method was developed to quantify the amount of Keto-β-Boswellic Acid (KBA) in different plant parts of Boswellia sacra and the resin exudates of the trunk. NIR spectroscopy was used for the measurement of KBA standards and B. sacra samples in absorption mode in the wavelength range from 700-2500nm. PLS regression model was built from the obtained spectral data using 70% of KBA standards (training set) in the range from 0.1ppm to 100ppm. The PLS regression model obtained was having R-square value of 98% with 0.99 corelationship value and having good prediction with RMSEP value 3.2 and correlation of 0.99. It was then used to quantify the amount of KBA in the samples of B. sacra. The results indicated that the MeOH extract of resin has the highest concentration of KBA (0.6%) followed by essential oil (0.1%). However, no KBA was found in the aqueous extract. The MeOH extract of the resin was subjected to column chromatography to get various sub-fractions at different polarity of organic solvents. The sub-fraction at 4% MeOH/CHCl 3 (4.1% of KBA) was found to contain the highest percentage of KBA followed by another sub-fraction at 2% MeOH/CHCl 3 (2.2% of KBA). The present results also indicated that KBA is only present in the gum-resin of the trunk and not in all parts of the plant. These results were further confirmed through HPLC analysis and therefore it is concluded that NIRS coupled with PLS regression is a rapid and alternate method for quantification of KBA in Boswellia sacra. It is non-destructive, rapid, sensitive and uses simple methods of sample preparation., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Aim: Acetyl-11-keto-β-boswellic acid (AKBA) is a potent anti-inflammatory compound limited by its low water solubility and bioavailability. To load AKBA on silver nanoparticles (AgNPs) to improve bioavailability and water solubility of the compound. Materials & methods: AKBA-AgNPs were chemically synthesized and characterized by UV–Vis spectrophotometry, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. AKBA and AKBA-Ag were studied for their sedative-hypnotic and anti-inflammatory efficacies. Results: Pretreatment with AKBA or AKBA-Ag caused significant dose-dependent sedative-hypnotic effects at 5 and 10 mg/kg intraperitoneal. The effects of AKBA-loaded AgNPs caused pronounced changes in mice compared with those of AKBA, and the AKBA-AgNPs demonstrated anti-inflammatory effects that were superior to those of AKBA. Conclusion: The loading of AKBA on nanoparticles improved its pharmacokinetic effects, and capacity for drug delivery. [ABSTRACT FROM AUTHOR]

In the course of our continuing exploration for novel bioactive lead compounds (s) from the species Boswellia , we have recently reported incensole derivatives isolated from Boswellia papyrifera Hochst. Given the known antidepressant-like effects of incensole and incensole acetate, we herein present that the low dose intraperitoneal administration of incensole derivatives, namely, incensfuran and incensone, showed significant antidepressant-like effects in the forced swim test (FST) and tail suspension test (TST). Furthermore, these compounds were evaluated for their anxiolytic potential in the elevated plus maze (EPM) and light dark box (LDB) tests and anticonvulsant effects in pentylenetetrazole (PTZ)-induced seizure tests. In the EPM test, administration of these compounds led to dose-dependent increases in open arm entries and in the time spent in EPM open arms. Similar results were obtained in the LDB test, wherein compounds these caused significant increases in the number of transitions between lit and dark compartments and the time spent in the lit compartment. The anxiolytic-like effects in the EPM were not reversed by pretreatment with flumazenil, whereas PTZ and bicuculline (BIC) completely abolished the anxiolytic effects, showing the involvement of the non-benzodiazepine binding sites of GABA A receptors. All four compounds induced significantly elevated brain GABA levels, indicating the involvement of a GABAergic mechanism. Additionally, molecular docking was conducted to elucidate the mode of action for the anxiolytic and anticonvulsant effects of these derivatives. Moreover, these compounds also possess drug-like properties and excellent ADMET profiles. Image 1 • The antidepressant-like effect of incensole and its derivatives (1–4) were evaluated. • Compounds 1–4 were evaluated for their anxiolytic and anticonvulsant effects. • Compounds 1 – 4 significantly increase brain GABA levels, indicating the involvement of a GABAergic mechanism. • Molecular docking was carried out to elucidate the mode of action for the anxiolytic and anticonvulsant effects of these derivatives. [ABSTRACT FROM AUTHOR]

The frankincense resin of botanically-certified Boswellia sacra was pyrolyzed and the smoke was trapped into water using self-developed assembly. Two compounds, namely 1,2,4a,9-tetramethyl-1,2,3,4,4a,5, 6,14b-octahydropicene ( 1 ) and 2,9-dimethylpicene ( 2 ) were isolated from n -hexane extract of the smoke-saturated water. Their structures were determined by means of spectroscopic data including ESIMS, 1 H NMR, 13 C NMR, and 2D NMR (COSY, HSQC, HMBC, and NOESY). Dehydration of C-3 alcohols in boswellic acids (BAs) lead to aromatization of ring A followed by dehydrogenation and demethylation to afford triaromatic derivative viz., 1,2,4a,9-tetramethyl-1,2,3,4,4a,5, 6,14b-octahydropicene ( 1 ) and finally penta-aromatic derivative viz., 2,9-dimethylpicene ( 2 ). Compounds 1 and 2 were screened for their antiproliferative effects on MDA-MB-231 breast cancer cells. It was found that these pyrolysate products were capable of inhibiting cancer cell growth. However, this growth inhibitory effect was less when compared to their precursor AKBA (3-acetyl-11-keto-β-boswellic acid). The antiproliferative activity is inversely proportional to loss of functional groups. [ABSTRACT FROM AUTHOR]