sealPurdue News

September 20, 2001

Pawpaw research results in new product for head lice

WEST LAFAYETTE, Ind. – The pawpaw tree is bearing new fruit for people with head lice.

Research completed at Purdue University has resulted in a new shampoo that removes the lice. Jerry McLaughlin, professor emeritus at Purdue who studied compounds in the bark of the pawpaw tree for more than 25 years, is taking his knowledge of pawpaw compounds from the laboratory to the market.

McLaughlin now serves as vice president of research, development and quality assurance and is chief scientific officer for Nature's Sunshine Products Inc., a company based in Provo, Utah. He is leading the effort to introduce the new product to the market.

"Head lice have become resistant to many of the products currently on the market, so this new product may be especially useful," McLaughlin says. "This is the first truly innovative new product for head lice to be released to the market in 50 years."

The product, called PawPaw Lice Remover Shampoo, was introduced this month after laboratory and clinical studies showed that it was effective in removing head lice. The product is now being used in a follow-up study in New Jersey to help school children with head lice.

"In studies conducted with more than 20 people, the shampoo has proven to be 100 percent effective in eliminating head lice," McLaughlin says.

He notes that of the three types of lice that infest humans, head lice are the most troublesome form in the United States, where 6 million to 15 million cases occur each year. Head lice are transmitted by person-to-person contact and by sharing articles such as combs, clothing and pillows.

Head lice target humans in three different developmental stages. In the first stage nits, or eggs, connect to the hair shaft. After seven to 10 days, the nits hatch and nymph lice appear. In stage three, the adult lice feed on the scalp and begin producing more eggs.

"The pawpaw product works by targeting the nymphs and adults and also by loosening the nits on the hair shaft so the nits comb out easily before they have a chance to hatch," McLaughlin says.

McLaughlin, who retired from Purdue in 1999, began studying compounds found in the bark of the pawpaw tree in 1976 while serving as a professor of pharmacognosy at Purdue. His initial studies identified a number of compounds, called annonaceous acetogenins, capable of controlling insects and pests.

"The pawpaw extract used in this shampoo has more than 50 annonaceous acetogenin compounds," he says. "It's a complicated mixture that the plant evolved to protect itself."

The annonaceous acetogenins are collected from the twigs and branches of the tree and extracted in a process designed to isolate and concentrate the compounds. Once extracted, the compounds are standardized using a bioassay McLaughlin developed during his years at Purdue. This procedure ensures that the product has a consistent concentration of annonaceous acetogenins, he says.

"It's been a bit of a struggle to pursue this research in product development because there are no commercial sources of these compounds, and samples can be collected from the tree only during the month of May," McLaughlin says. "My studies at Purdue showed that there is a peak in the biological activity of these compounds in May. During that time of year the plants pump up production to protect themselves against pests."

Purdue holds three patents for using the compounds to control lice and other pests. Nature's Sunshine Products Inc. has an exclusive license for using the technology to control various pests.

The pawpaw tree produces the largest edible tree fruit native to the United States, often reaching more than one pound. Pawpaws grow wild in the hardwood forests of 26 states in the eastern United States, ranging from northern Florida to southern Canada, and as far west as eastern Nebraska.

McLaughlin notes that numerous references to using pawpaw related plants to remove lice can be found in folklore.

"Some of these references date back hundreds of years," he says.

McLaughlin will discuss development of the product, and other pawpaw research under way, at the Second International Pawpaw Conference Friday and Saturday (9/21-22) in Frankfort, Ky. The conference is sponsored by Kentucky State University and The Pawpaw Foundation

Writer: Susan Gaidos, (765) 494-2081;

Source: Jerry McLaughlin, (801) 798-4161,

Purdue News Service: (765) 494-2096;

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