Vol. 9, No 1, 2011 pp. 57 - 64
DOI 10.2298/FUPCT1101057P
UDC 547.913 + 632.936.3 : 595.771
CHEMICAL COMPOSITION AND MOSQUITO REPELLENT ACTIVITY OF THE ESSENTIAL OIL OF PLECTRANTHUS INCANUS LINK
Mahesh Pal*, Anil Kumar, Shri Krishna Tewari
Phytochemistry Division, National Botanical Research Institute,
Lucknow U. P., India-226001
Abstract.The chemical composition of the essential oil obtained from the leaves of Plectranthus incanus Link, with the yield of 0.6% (w/v), was analyzed by GC and GC/MS. A total of 16 constituents, representing 95.2% of the oil, were identified. The major components of the oil were fenchone (6.0%), piperitone oxide (32.4%), piperitenone (3.0%) and piperitenone oxide (41.5%). The repellent activity of the volatile oil at different concentrations was measured by the protection period against the bites of Anopheles stephensi and Culex fatigans. The tested oil had stronger repellent activity than citronella oil, which was used as a positive control. LC50 (30 min) for P. incanus oil against An. stephensi and C. fatigans were 23.8 and 19.6 μl/L air, respectively, whereas LC50 of citronella oil were 31.7 and 31.0 μl/L air. Thus, P. incanus may be regarded as a potential valuable source of chemicals that have strong mosquito repellent activity, and could be used for the preparation of mosquito repellent formulations.
Key words: Plectranthus incanus Link, essential oil, mosquito repellent activity, Anopheles stephensi, Culex fatigans
ODBOJNO DEJSTVO PREMA KOMARCIMA I HEMIJSKI SASTAV ETARSKOG ULJA BILJNE VRSTE PLECTRANTHUS INCANUS LINK
Hemijski sastav etarskog ulja izolovanog iz listova biljne vrste Plectranthus incanus Link, sa prinosom od 0,6% (v/m), analiziran je pomoću gasne hromatografije i gasne hromatografije sa masenom detekcijom (GC i GC/MS). Uspešno je identifikovano ukupno 16 jedinjenja, koja su sačinjavala 95,2% ulja. Glavni sastojci su bili fenhon (6,0%), piperiton oksid (32,4%), piperitenon (3,0%) i piperitenon oksid (41,5%). Testirano je odbojno dejstvo dobijenog ulja (pri različitim koncentracijama) prema komarcima, merenjem perioda zaštite od ugriza Anopheles stephensi i Culex fatigans. Analizirano ulje pokazalo je jače odbojno dejstvo prema komarcima od "citronela" ulja, koje je korišćeno kao pozitivna kontrola. Pored toga, dobijene LC50 vrednosti (merenje je vršeno nakon 30 minuta) za An. stephensi i C. fatigans su bile niže u slučaju P. incanus (23,8 i 19,6 μl/L vazduha) u odnosu na "citronela" ulje (31,7 i 31,0 μl/L vazduha). Prema tome, biljna vrsta P. incanus bi se mogla smatrati potencijalnim vrednim izvorom jedinjenja sa jakim odbojnim dejstvom prema komarcima, te bi se mogla koristiti za pripremu odgovarajućih zaštitnih preparata.
Ključne reči: Plectranthus incanus, etarsko ulje, odbojno dejstvo prema komarcima, Anopheles stephensi, Culex fatigan
