Geraniol – A review update

Geraniol is an acyclic isoprenoid monoterpene that is biosynthesised by a large number of aromatic plants. It is widely used in cosmetics, household products and pharmaceuticals, because of its low toxicity and environmentally-friendly profile. An increasing demand for the compound has encouraged research into alternative synthetic routes, and great efforts are still aimed to increase the compound yield through heterologous production in micro-organisms, using a variety of different strategies. Geraniol is proven to exhibit various biological activities, including antitumour, anti-inflammatory, anti-oxidant, antimicrobial, hepatoprotective, cardioprotective and neuroprotective effects. The lipophilic compound is a relatively good penetration enhancer and can be used to increase transdermal drug delivery. Encapsulation of the compound using different methods has circumvented problems associated with the dispersal of the non-polar entity within aqueous matrices, such as foods, to prevent spoilage. The volatile nature of the compound lends itself to applications such as postharvest fumigation of grain crops to protect against invading insects and mycotoxin-producing fungi, and as a mosquito repellent. In addition, administration via inhalation can combat respiratory pathogens susceptible to geraniol, while combating inflammation. Using the multidisciplinary Scopus database, it became evident through a bibliometric analysis of the available literature spanning the past 12 years that, despite a host of research reports documenting the anticancer activity of the compound, research is limited to in vitro, in silico and in vivo experiments, while clinical trials are completely lacking. This review is an update to our 2010 publication on the same topic and aims to reflect and compare the progress, and to highlight the potential and opportunities for further evidence based research.