Potent bioactivities of the endemic annonaceae heighten its dire conservation status

Abstract

Sri Lanka records 17 endemic species of the Annonaceae family. Worldwide, the Annonaceae are known to possess compounds with pharmaceutically important properties such as anticancer and insecticidal actions. In an attempt to investigate the mosquito larvicidal and antioxidant activities of the endemic Annonaceae plants, twelve plant species were collected. Of the 71 extracts investigated from various plant parts, five plants showed significant larvicidal activity with the CH2Cl2 extracts of the leaves of G. hookeri and G. gardneri (LC50 at 48 h = 0.4 and 0.3 ppm, respectively) exhibiting potency compared to the known larvicide (4S)-4-methyl-2-(11-dodecynyl)-2-butenolide (LC50=0.3 ppm). Compared to the percent radical scavenging activity of the standard dl-α tocopherol (55.84), the MeOH extracts of the stem of A. hortensis (56.30), the leaves of U. semecarpifolia (57.33), and the seeds of X. nigricans (62.06) showed very promising activity. Significantly, it is recorded that two of the Sri Lankan endemic Annonaceae plants are extinct (P. moonii and A. hortensis) and the rest, except for U. sphenocarpa, are critically endangered, endangered, vulnerable or near threatened. These grim statistics highlight not only the urgency and the importance of biodiversity conservation of the endemic Annonaceae of Sri Lanka but also of investigating the plants for new phamacophores.