Terpenes in Human Health - Natural Products Chemistry: Sources, Separations, and Structures - page 107

200 180 160 140 120 100 80 60 40 20 0

ppm

FIGURE 10.8 Example of a 13 C NMR spectrum of the steroid, diosgenin.

1.0

2061

0.9

642

2878 1634

0.8

2930

0.7

0.6

0.5

3420

0.4

4000 3500 3000 2500

Wave Number cm -1

2000 1500 1000 500

FIGURE 10.9 Typical IR spectrum of the steroid, diosgenin.

10.4 NEEM OIL AND OTHER LIMONOIDS
The neem tree is a fast growing tree native to South Asia, and is grown on a large
scale in India. The tree has been used for medicinal purposes and pest control in India
for thousands of years. It is used in Ayurvedic medicine to reduce fevers and has been
shown to contain effective antimalarial ( Plasmodium falciparum ) compounds. The
bark and leaves have several uses: antiseptic, antiviral, anti-inlammatory, antiulcer,
and antifungal. Neem oil is also effective as a repellant (insecticide), miticide, and fun-
gicide, and functions as an antifeedant, which discourages insects' feeding patterns.