Gold, Frankincense, Myrrh…Did the Kings Forget Palo Santo?

The holiday season is upon us and celebrations of traditions surrounding remembrances in various religions have commenced. Amongst them is the biblical sojourn of the three wise men to the Christ Child. These kings carried to him their gifts of gold, frankincense, and myrrh. All were prized and rare possessions of that time. I have written in the past why this dynamic duo of oils was considered “gifts even more precious than gold.”

For this reason I became intrigued with another essential oil which comes from the same botanical family of  frankincense, Burseracea. This oil is Palo Santo (Bursera graveolens). Its Spanish translation literally means “holy wood” or “sacred wood.” In fact, in South America it is often used for spiritual purposes similar to what frankincense is used for in Northern America.

This made me wonder if Palo Santo was overlooked in ancient times or if it is just now being “rediscovered”. I have a thing for humble sidekicks, so I set out to find the answer to this question about another powerful South American oil.

It was quite an afternoon and late evening for me, because there wasn’t much published online on this oil. However, I did find 5 amazing reasons to convince me of its safety and power.

(As noted in the past, full abstracts are included in italics along with my summaries due to FDA regulations.)


My Top 5 Reasons To Pay Attention to the Power of  Palo Santo


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1. The Potent Immune Supporting Power of Limonene

Bursera graveolens, Palo Santo, is high in the constituent limonene. Limonene is a powerful monoterpene studied for supporting a variety of health issues. (1-11) In the following in vitro abstract, Palo Santo was shown to inhibit the growth of breast tumor cells:

Bursera graveolens is a wild tree of commercial importance native to the Neotropics, which has been widely used in folk medicine. In the present study, the chemical composition and anti-proliferative properties of the essential oil from B. graveolens were assayed. The chemical composition of the essential oil, determined by GC-MS, was complex and dominated by limonene (26.5%). Bursera oil inhibited the growth of MCF-7 breast tumor cells as well as amastigotes of L. amazonensis, with IC50 values of 48.9 +/- 4.3 and 36.7 +/- 4.7 microg/mL, respectively. In addition, the cytotoxicity of the oil was 103.9 +/- 7.2 microg/mL against peritoneal macrophages from BALB/c mice. These results demonstrate that the essential oil from B. graveolens is a promissory antiproliferative product. (1)

Limonene itself has been studied in vitro, in vivo, and in a small amount of human trials for its role in various health issues. One study reported that it may have protective effects against rodent solid tumor types due to its induction of liver enzymes which can lead to carcinogen detoxification. The same study also stated that limonene may also assist with tissue redifferention. (2)

An in vitro study with human prostate cancer cells sought to determine if d-limonene would enhance tumor response to the chemotherapeutic drug, docetaxel. (3) The authors concluded:

 Our results show, for the first time, that d-limonene enhanced the antitumor effect of docetaxel against prostate cancer cells without being toxic to normal prostate epithelial cells. The combined beneficial effect could be through the modulation of proteins involved in mitochondrial pathway of apoptosis. d-Limonene could be used as a potent non-toxic agent to improve the treatment outcome of hormone-refractory prostate cancer with docetaxel. (3)

In a human trial of 32 patients with refractory solid tumors, 99 courses of d-limonene were administered for 21-day cycles (dose of .5-12mg/m2/day). Ten additional breast cancer patients received 15 cycles of d-limonene at 8g/m2/day. The results and conclusions are below: (4)

RESULTS: The MTD was 8 g/m2 per day; nausea, vomiting and diarrhea were dose limiting. One partial response in a breast cancer patient on 8 g/m2 per day was maintained for 11 months; three patients with colorectal carcinoma had prolonged stable disease. There were no responses in the phase II study. Peak plasma concentration (Cmax) for D-limonene ranged from 10.8+/-6.7 to 20.5+/-11.2 microM. Predominant circulating metabolites were perillic acid (Cmax 20.7+/-13.2 to 71+/-29.3 microM), dihydroperillic acid (Cmax 16.6+/-7.9 to 28.1+/-3.1 microM), limonene-1,2-diol (Cmax 10.1+/-8 to 20.7+/-8.6 microM), uroterpenol (Cmax 14.3+/-1.5 to 45.1+/-1.8 microM), and an isomer of perillic acid. Both isomers of perillic acid, and cis and trans isomers of dihydroperillic acid were in urine hydrolysates. Intratumoral levels of D-limonene and uroterpenol exceeded the corresponding plasma levels. Other metabolites were trace constituents in tissue. (4)

CONCLUSIONS: D-Limonene is well tolerated in cancer patients at doses which may have clinical activity. The favorable toxicity profile supports further clinical evaluation.

Finally, a review in Alternative Medicine lists other uses for d-limonene including relief from stomach discomfort and support for the gallbladder: (5)

D-limonene is one of the most common terpenes in nature. It is a major constituent in several citrus oils (orange, lemon, mandarin, lime, and grapefruit). D-limonene is listed in the Code of Federal Regulations as generally recognized as safe (GRAS) for a flavoring agent and can be found in common food items such as fruit juices, soft drinks, baked goods, ice cream, and pudding. D-limonene is considered to have fairly low toxicity. It has been tested for carcinogenicity in mice and rats. Although initial results showed d-limonene increased the incidence of renal tubular tumors in male rats, female rats and mice in both genders showed no evidence of any tumor. Subsequent studies have determined how these tumors occur and established that d-limonene does not pose a mutagenic, carcinogenic, or nephrotoxic risk to humans. In humans, d-limonene has demonstrated low toxicity after single and repeated dosing for up to one year. Being a solvent of cholesterol, d-limonene has been used clinically to dissolve cholesterol-containing gallstones. Because of its gastric acid neutralizing effect and its support of normal peristalsis, it has also been used for relief of heartburn and gastroesophageal reflux (GERD). D-limonene has well-established chemopreventive activity against many types of cancer. Evidence from a phase I clinical trial demonstrated a partial response in a patient with breast cancer and stable disease for more than six months in three patients with colorectal cancer. (5)

Other abstracts of d-limonene further support its role in breast health (6) and immune support. (7)


PageLines- forms-icon.png2. The Silver Lining of Lignans

Interestingly, I found a study with a menthanol extract of Palo Santo that not only isolated triterpenes but also lignans, which are polyphenolic compounds found in certain plants. This study abstract reports on these constituents in Palo Santo and the oil’s in vitro effect on human fibrosarcoma cells:

A new 4alpha-aryltetralin-type lignan called burseranin (1) and a known analogous lignan picropolygamain (2) were isolated along with known triterpenes, lupeol and epi-lupeol from the methanol extract of stems of Bursera graveolens, which showed a remarkable inhibitory activity against human HT1080 fibrosarcoma cells. The whole structure of 1 was established based on combined spectral studies and the absolute structure for 2 was first confirmed by CD spectral evidence. In addition, cytotoxic activities of the stem (methanol) extract and its components are evaluated in this paper. (8)


We Interrupt This Blog for Geeks: More on Lignan and Wellness Effects

Lignan intake was associated with decreased incidence of breast cancer in a cohort study in 2007. (9) This 2007 study in Molecular Nutrition & Food Research summarizes lignans role in breast health:

Lignans are a large group of fiber-associated phenolic compounds widely distributed in edible plants. Some of the ingested plant lignans are converted by intestinal microbiota to enterolignans, enterodiol (END) and enterolactone (ENL), the latter of which has been thought to be the major biologically active lignan, and suggested to be associated with low risk of breast cancer. In line with this, administration of plant lignans which are further metabolized to ENL, or ENL as such, have been shown to inhibit or delay the growth of experimental mammary cancer. The mechanism of anticarcinogenic action of ENL is not yet fully understood, but there is intriguing evidence for ENL as a modulator of estrogen signaling. These findings have generated interest in the use of lignans as components of breast cancer risk reducing functional foods. Identification of target groups, who would benefit most, is of pivotal importance. Therefore, further identification and validation of relevant biomarkers, which can be used as indicators of lignan or ENL action and breast cancer risk reduction at different stages of the disease, are of importance. (10)

In another 11 year cohort study with 477, 312 men and women (mostly aged 35-70 years) living in 10 European countries, the intake of lignans and flavonols were shown to be inversely associated with bladder cancer. (11) So, this oil could be another thing to add to your “epigenetic” wellness toolkit. (12)


PageLines- forms-icon.png3. Sesquiterpenes!!

I love sesquiterpenes for many reasons. Amongst them are their calming and oxygenating effects of the brain. (13) Palo Santo contains sesquiterpenes (14-19) which means it is now welcome to the “oil club” with such esteemed members as frankincense, myrrh, (13) and cedarwood!

In the course of studies on the constituents of the woody material of Bursera graveolens, the aroma components that provide its characteristic spicy, sweet and balsamic odor were investigated using GC/MS. Five compounds, 15, were isolated from the volatile oil obtained by diethyl ether extraction of B. graveolens wood chips, and their structures were elucidated by means of NMR studies. Their structures were determined as (?)-dihydro-?-agarofuran (1), (?)-5,11-epoxy-4?,5?,10?-eudesm-1-ene (2), (?)-4?-hydroxydihydroagarofuran (3), (?)-3?,4?-oxidoagarofuran (4) and (?)-10-epi-?-eudesmol (5). Of these, (?)-5,11-epoxy-4?,5?,10?-eudesm-1-ene (2) is a new sesquiterpenoid that has not previously been reported in literature, and the presence of (?)-dihydro-?-agarofuran (1), (?)-4?-hydroxydihydroagarofuran (3), (?)-3?,4?-oxidoagarofuran (4) and (?)-10-epi-?-eudesmol (5) in B. graveolens is reported for the ?rst time. (14)

Here are some more abstracts demonstrating the constituents of Palo Santo:

  • The chemical composition of the leaf oil of Bursera graveolens (Kunth) Triana et Planch. was studied by GC and GC/MS. Ninety-seven constituents were identified, which constituted more than 92% of the leaf oil composition. The most prominent compounds were limonene (30.7%), (E)-?-ocimene (20.8%) and ?-elemene (11.3%). The composition of the leaf oil was characterized by its richness in monoterpene and sesquiterpene hydrocarbons. (15)
  • Three different extracts were separated by diethyl ether extraction, simultaneous steam distillation extraction and roasted aroma extraction (dry distillation) from Bursera graveolens. It was possible to identify 100 compounds in the three different extracts by GC–MS. The odour-active compounds present in the extracts were evaluated by gas chromatography–olfactometry (GC–O). It was estimated that mono- or sesquiterpenoids contributed to woody, herbal and minty aromas of the woody material of B. graveolens. On the other hand, the roast aroma produced by burning chips included several aroma compounds, such as cyclotene and vanillin (16)
  • The steam-distilled essential oil from stem part of Bursera graveolens was analyzed by GC and GC/MS. The oil was found to consist of monoterpenes (78.2%) and sesquiterpenes (9.6%). The major constituents of B. graveolens oil were limonene (58.6%), and ?- terpineol (10.9%). (17)



PageLines- forms-icon.png4. They May Have a Way of Making Microbes Unwelcome

An in vitro study demonstrated how Palo Santo may have microbe-inhibiting properties:

Bursera graveolens (Burseraceae), known in Colombia as “sasafrás”, is useful for its medicinal properties and is rich in secondary metabolites. In our research, we carried out antimicrobial tests of several fractions and ethanolic extracts from aerial parts against Bacillus subtilis and Staphylococcus aureus, that showed growth inhibitory activity when applied at 250 mg/mL for extracts and 150 mg/mL for fractions. We carried out an antiinflamatory assay also, that showed 71% of inhibition by extracts (81% of Indomethacin) and 70% of inhibition by fractions (78% of Indomethacin). Phytochemical investigation of the bark of Bursera graveolens (Burseraceae) yielded three tetracyclic triterpene acids that have oxygenation in C-3, carboxylic acid in C-21 and unsaturation in C-24 and have been identified as 3-oxotirucalla-8,24-dien-21-oic acid (b-elemonic acid), 3a-hydroxytirucalla-8,24-dien-21-oic acid (a-elemolic acid) and 3a-hydroxytirucalla-7,24-dien-21-oic acid. The isolated compounds were identified using spectroscopic methods including one and two-dimensional Nuclear Magnetic Resonance (COSY, HMQC, HMBC, NOESY) experiments and comparison with published data. This is the first report of the isolated compounds in Bursera graveolens and they have a very important chemotaxonomic significance within the Burseraceae family and related families from the order Rutales. (20)


PageLines- forms-icon.png5. Safety and Toxicity, No Worries Here

In my research, I couldn’t find any toxic repots of Palo Santo. In fact, its main constituent d-limonene, as mentioned above, is considered very safe.

To be sure, I looked into all its impressive constituents of sesquiterpenes, monoterpenes (d-limonene), monoterpene alcohols (alpha- terpineol), terpenoids (cavone), and even minute amounts of menthofuran (5-8%). This made me jump down another rabbit hole. (I’m beginning to give Alice a run for her money!)

I was set back about 2 hours researching this latter constituent of menthofuran, which is found in pennyroyal. (21-25) However, I was put to ease when I calculated several of the toxicity reports of Pennyroyal (note, not Palo Santo).

For example, in one report from the Annals of Internal Medicine, one would need to swallow about 7 bottles of pure menthofuran, and Palo Santo only contains 5-8% of this constituent. This was equivalent to 70 bottles in this case! (25) (My calculation- 1 ng= 3.5 oz, 1 ng of menthofuran would equal 3.5oz/ml. A bottle of essential oil is .5 oz/15 ml, this would be 7 full bottles of menthofuran, menthofuran at 8% would equal swallowing about 7o bottles of Palo Santo.) As noted in my small novelette on essential oil safety, “please don’t swallow a full bottle of oil,” much less 70!



female friends in fallPalo Santo is an oil to have on hand for its immune, oxygenating, and brain supporting properties. It now has a place in my oil cabinet sitting contently besides its buddies cedarwood and myrrh, and yes, even Sacred Frankincense nudges it from nearby!


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Disclaimer: This information is applicable ONLY for therapeutic, Grade A essential oils. This information DOES NOT apply to essential oils that have not been AFNOR and ISO standardized. There is no quality control in the United States and oils labeled as “100% pure” need only contain 5% of the actual oil. The rest of the bottle can be filled with fillers and sometimes toxic ingredients that can irritate the skin.

This information is for information purposes only and is not intended to diagnose, treat, or prescribe for any illness.



(1) Chemical composition and anti-proliferative properties of Bursera graveolens essential oil. Nat Prod Commun. 2012 Nov;7(11):1531-4. PMID: 23285824

(2) Chemoprevention and therapy of cancer by d-limonene. Crit Rev Oncog. 1994;5(1):1-22. PMID: 7948106

(3) d-Limonene sensitizes docetaxel-induced cytotoxicity in human prostate cancer cells: Generation of reactive oxygen species and induction of apoptosis. J Carcinog. 2009; 8: 9. Published online May 21, 2009. doi: 10.4103/1477-3163.51368. PMCID: PMC2699604

(4) Phase I and pharmacokinetic study of D-limonene in patients with advanced cancer. Cancer Research Campaign Phase I/II Clinical Trials Committee. Cancer Chemother Pharmacol. 1998;42(2):111-7.

(5) D-Limonene: safety and clinical applications. Altern Med Rev. 2007 Sep;12(3):259-64.

(6) d-Limonene: a bioactive food component from citrus and evidence for a potential role in breast cancer prevention and treatment . Oncology Reviews. September 2010.

(7) Prevention and therapy of cancer by dietary monoterpenes. Journal of Nutrition. 1999 March 129(3):775S-778S.

(8) A new and known cytotoxic aryltetralin-type lignans from stems of Bursera graveolens. Chem Pharm Bull (Tokyo). 2005 Feb;53(2):229-31. PMID: 15684524

(9) Touillaud MS, Thiébaut ACM, Fournier A, Niravong M, Boutron-Ruault M-C, Clavel-Chapelon F. Dietary lignan intake and postmenopausal breast cancer risk by estrogen and progesterone receptor status. Journal of the National Cancer Institute. 2007;99(6):475-486. doi:10.1093/jnci/djk096.

(10) Role of dietary lignans in the reduction of breast cancer risk. Mol Nutr Food Res. 2007 Jul;51(7):857-66. PMID: 17576639

(11) Flavonoid and lignan intake in relation to bladder cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Br J Cancer. 2014 Oct 28;111(9):1870-80. doi: 10.1038/bjc.2014.459. Epub 2014 Aug 14.

(12) Epigenetic impact of dietary polyphenols in cancer chemoprevention: lifelong remodeling of our epigenomes. Pharmacol Res. 2012 Jun;65(6):565-76. doi: 10.1016/j.phrs.2012.03.007. Epub 2012 Mar 22.

(13) Xu J, Guo Y, Zhao P, Guo P, Ma Y, Xie C, Jin DQ, Gui L. Four new sesquiterpenes from Commiphora myrrha and their neuroprotective effects. Fitoterapia. 2012 Jun;83(4):801-5. doi: 10.1016/j.fitote.2012.03.016. Epub 2012 Mar 20. PMID: 22465505

(14) Yukawa, C., Iwabuchi, H., Kamikawa, T., Komemushi, S. and Sawabe, A. (2004), Terpenoids of the volatile oil of Bursera graveolens. Flavour Fragr. J., 19: 565–570. doi: 10.1002/ffj.1356

(15) Leaf Oil Composition of Bursera graveolens (Kunth) Triana et Planch. Journal of Essential Oil Research (Impact Factor: 0.55). 09/2009; 21(5):387-389. http://www.researchgate.net/publication/239790193_Leaf_Oil_Composition_of_Bursera_graveolens_%28Kunth%29_Triana_et_Planch

(16) Yukawa, C., Imayoshi, Y., Iwabuchi, H., Komemushi, S. and Sawabe, A. (2006), Chemical composition of three extracts of Bursera graveolens. Flavour Fragr. J., 21: 234–238. doi: 10.1002/ffj.1563

( 17) Young, D. Gary, et al. Essential oil of Bursera graveolens (Kunth) triana et planch from Ecuador. Journal of Essential Oil Research. 2007; 19(6): 525-526. DOI: 10.1080/10412905.2007.9699322

(18) Eudesmane-Type Sesquiterpenoids in the Volatile Oil from Bursera graveolens. Journal of Oleo Science. 2004. 53(7):343-348. http://ci.nii.ac.jp/naid/10013160900/

(19) Sesquiterpenoids: The Holy Fragrance Ingredients. The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, Department of Applied Chemistry, School of Chemical & Material Engineering. Jiang Nan University, China.

(20) Triterpenos aislados de corteza de Bursera graveolens (Burseraceae) y su actividad biologica. Revista Brasileira de Farmacognosia. 2005. 15(4), 283-286. http://dx.doi.org/10.1590/S0102-695X2005000400003

(21) Menthofuran-dependent and independent aspects of pulegone hepatotoxicity: roles of glutathione. Journal of Pharmacology and Experimental Therapeutics. 1990. 253(2): 567-572.

(22) http://ec.europa.eu/food/fs/sc/scf/out133_en.pdf

(23) http://www.mskcc.org/cancer-care/herb/pennyroyal

(24) http://www.ncbi.nlm.nih.gov/pubmed/8633832

(25) Pennyroyal toxicity: measurement of toxic metabolite levels in two cases and review of the literature. Ann Intern Med. 1996. Apr 15;124(8):726-34.

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