Santalol

Molecules. 2017 Jul 8;22(7). pii: E1139.

Antifungal and Ichthyotoxic Sesquiterpenoids from Santalum album Heartwood.[Pubmed: 28698478]

METHODS AND RESULTS:
In our continuing study on a survey of biologically active natural products from heartwood of Santalum album (Southwest Indian origin), we newly found potent fish toxic activity of an n-hexane soluble extract upon primary screening using killifish (medaka) and characterized α-Santalol and β-Santalol as the active components. The toxicity (median tolerance limit (TLm) after 24 h at 1.9 ppm) of α-Santalol was comparable with that of a positive control, inulavosin (TLm after 24 h at 1.3 ppm). These fish toxic compounds including inulavosin were also found to show a significant antifungal effect against a dermatophytic fungus, Trichophyton rubrum. Based on a similarity of the morphological change of the immobilized Trichophyton hyphae in scanning electron micrographs between treatments with α-Santalol and griseofulvin (used as the positive control), inhibitory effect of α-Santalol on mitosis (the antifungal mechanism proposed for griseofulvin) was assessed using sea urchin embryos.
CONCLUSIONS:
As a result, α-Santalol was revealed to be a potent antimitotic agent induced by interference with microtubule assembly. These data suggested that α-Santalol or sandalwood oil would be promising to further practically investigate as therapeutic agent for cancers as well as fungal skin infections.

Anticancer Res. 2015 Oct;35(10):5353-7.

Survivin Down-regulation by α-Santalol Is Not Mediated Through PI3K-AKT Pathway in Human Breast Cancer Cells.[Pubmed: 26408696]

α-Santalol, a terpenoid found in sandalwood oil, has been shown to inhibit cancer cell growth in vitro by inducing apoptosis. This study was performed to investigate the anticancer properties of α-Santalol associated with the induction of apoptosis in cultured MCF-7 [estrogen receptor (ER)-positive, and wild-type p53)] and MDA-MB-231 (ER-negative and mutant p53) breast cancer cells.
METHODS AND RESULTS:
Expression of major proteins examined in the study were determined using a standard western blot protocol and analyzed by LICOR-Odyssey infra-red scanner. Total protein levels of survivin were confirmed by survivin enzyme-linked immunosorbent assay (ELISA) kit. Cell viability was assessed by the trypan blue dye exclusion assay, and caspase-3 activity was determined by caspase-3 (active) ELISA kit. Treatment of breast cancer cells for 6 and 9 h with α-Santalol (20, and 40 μM) resulted in statistically significant concentration-dependent down-regulation of survivin. Phosphorylated protein kinase B (pAKT) levels were found to be slightly up-regulated despite the down-regulation of survivin. Pharmacological inhibition of the phosphoinositide 3-kinase - protein kinase B (PI3K-AKT) pathway did not result in a synergistic/additive increase in cell death or caspase-3 activity caused by α-Santalol.
CONCLUSIONS:
The study reveals that survivin down-regulation by α-Santalol in breast cancer cells is not mediated through the PI3K-AKT pathway.

Pharm Res. 2017 Sep;34(9):1897-1907.

Chemoprevention of Breast Cancer by Transdermal Delivery of α-Santalol through Breast Skin and Mammary Papilla (Nipple).[Pubmed: 28589445 ]

Almost all breast cancers originate from epithelial cells lining the milk ducts in the breast. To this end, the study investigated the feasibility of localized transdermal delivery of α-Santalol, a natural chemopreventive agent to the breast.
METHODS AND RESULTS:
Different α-Santalol formulations (cream, solution and microemulsion) were developed and the in vitro permeability was studied using excised animal (porcine and rat) and human breast skin/mammary papilla (nipple). The in vivo biodistribution and efficacy studies were conducted in female rats. A chemical carcinogenesis model of breast cancer was used for the efficacy studies.Phospholipid based α-Santalol microemulsion showed the highest penetration through the nipple and breast skin. Delivery of α-Santalol through the entire breast (breast skin and nipple) in vivo in rats resulted in significantly higher concentration in the mammary gland compared to transdermal delivery through the breast skin or nipple. There was no measurable α-Santalol concentration in the blood. Transdermal delivery of α-Santalol reduced the tumor incidence and tumor multiplicity. Furthermore, the tumor size was significantly reduced with α-Santalol treatment.
CONCLUSIONS:
The findings from this study demonstrate the feasibility of localized transdermal delivery of α-Santalol for chemoprevention of breast cancer.

Sheng Wu Gong Cheng Xue Bao. 2018 Jun 25;34(6):862-875.

Progress in biosynthesis of santalene and santalol.[Pubmed: 29943532]

Santalene and Santalol are the main components of valuable perfume sandalwood essential oil, and have good antibacterial, anti-oxidation and anti-tumor activities.
METHODS AND RESULTS:
Commercial sandalwood essential oil is mainly extracted from sandalwood tree that grows slowly and is difficult to cultivate. In addition, the extraction recovery of sandalwood essential oil from sandalwood tree is too low to meet the market demand. These factors make sandalwood essential oil expensive. An option is to use genetic engineering and molecular biological methods to heterologously express related synthase of santalene and Santalol in microbial host.
CONCLUSIONS:
In this paper, the biosynthesis progress of santalene and Santalol synthase, as well as the optimization of mevalonate metabolic pathways in the hosts are summarized. Furthermore, the strategies of applying protein engineering technology to carry out orthomutation of santalene synthase were also discussed, to provide reference for the optimal biosynthesis of santalene and Santalol.