Summertime hikes and\u00a0afternoons in the backyard\u00a0can be ruined by\u00a0mosquito\u00a0bites. So,\u00a0many people apply topical\u00a0synthetic repellents like DEET\u00a0before heading outside,\u00a0but\u00a0there is a growing market for\u00a0natural\u00a0repellants\u00a0that could be less irritating to the skin and\u00a0more environmentally friendly.\u00a0In\u00a0ACS Omega, researchers\u00a0describe\u00a0their new\u00a0plant-based\u00a0formulation,\u00a0a\u00a0patchouli oil-infused\u00a0lotion\u00a0that\u00a0protected\u00a0against\u00a0mosquitoes\u00a0as effectively as\u00a0a\u00a0commercially\u00a0available DEET\u00a0formulation.\u00a0<\/p>\n
“Unlike many natural repellents that lose effectiveness quickly due to volatility, our formulation achieved complete protection against\u00a0Aedes aegypti\u00a0for up to\u00a0three hours\u00a0at a relatively low concentration\u00a0of patchouli oil.” \u2013 Lizandra Lima Santos<\/p>\n
A team of researchers led by Lizandra Lima Santos hypothesized that patchouli oil’s rich, earthy aroma –\u00a0which makes it a popular\u00a0ingredient\u00a0in\u00a0incense and perfume\u00a0–\u00a0could act as a sort\u00a0of invisibility cloak,\u00a0overwhelming\u00a0a\u00a0mosquito’s sense of smell and making the wearer\u00a0undetectable.\u00a0That’s\u00a0how other bio-based natural alternatives like citronella and eucalyptus oils\u00a0work, but\u00a0their ability to prevent mosquito bites\u00a0doesn’t\u00a0last as long as\u00a0their\u00a0synthetic counterparts. Patchouli oil also breaks down quickly when exposed to air,\u00a0which challenged the team to create a stable formulation\u00a0for their repellent\u00a0while preserving the\u00a0oil’s\u00a0activity.\u00a0So, they\u00a0combined\u00a0patchouli oil\u00a0with\u00a0an unscented\u00a0cream\u00a0base\u00a0to create\u00a0an effective, long-lasting,\u00a0anti-mosquito lotion.\u00a0<\/p>\n
The researchers asked volunteers to\u00a0coat their forearms with\u00a0either\u00a0the patchouli oil\u00a0lotion\u00a0or a commercially available DEET\u00a0lotion,\u00a0while one unlucky participant acted as\u00a0a\u00a0control\u00a0with\u00a0no repellant.\u00a0Participants\u00a0then stuck their arms\u00a0in\u00a0a\u00a0cage\u00a0filled with 50 hungry\u00a0Aedes\u00a0aegypti\u00a0mosquitoes\u00a0over\u00a0three hours.\u00a0The team\u00a0observed\u00a0no bites on arms\u00a0treated with the\u00a0patchouli-infused\u00a0and DEET\u00a0lotions,\u00a0while\u00a0the\u00a0bare\u00a0arms unsurprisingly had lots of\u00a0bites.\u00a0“Unlike many natural repellents that lose effectiveness quickly due to volatility, our formulation achieved complete protection against\u00a0A.\u00a0aegypti\u00a0for up to\u00a0three hours\u00a0at a relatively low concentration,”\u00a0says Lima Santos.\u00a0<\/p>\n
One of the most surprising findings was the\u00a0high level\u00a0of repellency achieved at a low concentration of\u00a0patchouli\u00a0oil.\u00a0“Natural repellents are often expected to require higher doses to match the performance of synthetic compounds,”\u00a0says\u00a0Lima Santos,\u00a0“so observing complete protection for\u00a0three hours\u00a0was particularly encouraging.”\u00a0<\/p>\n
These\u00a0initial\u00a0test results\u00a0suggest that the patchouli oil cream offers\u00a0meaningful protection\u00a0against mosquito bites.\u00a0Next, the researchers plan\u00a0to conduct\u00a0targeted toxicological and clinical studies to\u00a0determine\u00a0the\u00a0new\u00a0formulation’s long-term safety.\u00a0<\/p>\n
Source:<\/p>\n
American Chemical Society<\/a><\/p>\n Journal reference:<\/p>\n