Phytochemicals and Bioactive Compounds in Tropical and Subtropical Fruits - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 57

Table 4.3. Plant sterols of some tropical and subtropical fruit. 1

Total
Phytosterols Fruit Campesterol Stigmasterol Sitosterol

Avocado 4.1 0.3 61.8 75.2

Banana 1.5 1.8 11 14

1.3 1.3 8.4 11.6

Grapefruit 2.5 1.0 15 18

1.4 0.2 14.3 20.0

Kiwi 0.44 1.4 7.2 9.1

Lemon 3.3 1.3 13 18

Orange 3.0 1.0 20 24

3.4 0.9 17 22.8

Passion fruit 8.8 0.62 34 44

Pineapple 3.8 0.44 11 17

Watermelon 0.18 0.26 0.91 1.3

1 mg/100 g, fresh-wt basis.
Source: Normen et al. (1999); Piironen et al. (2003).

phytosterol composition in terms of campesterol, stigmas-
terol, and sitosterol is shown in Table 4.3.
β

antimicrobial effect under appropriate conditions. Molds
growth was reported to be inhibited by naturally occurring
ethyl p -methoxycinnamate at concentrations of 10-50 ppm
(Huang and Zayas, 1991).

-Sitosterol is the main phytosterol found in fruits, and
its proportion ranges between 72% and 86% (Piironen et al.,
2003). Avocado fruit has been found to be a good source of
phytosterols, and the total sterol content in avocado fresh
fruit was 75.2 mg/100 g, fresh-wt (Piironen et al., 2003).
A study by Normen et al. (1999) on phytosterol content in
fruits and vegetables found watermelon to have the low-
est total phytosterol content (fresh-wt) of 1.3 mg/100 g
and passion fruit to have the highest phytosterol content of
4.4 mg/100 g among the analyzed fruits.

Antiviral activity
Phenolics
A number of flavonoids present in foods of plant origin pos-
sess antiviral activity. Quercetin, a flavonol aglycone, found
in a number of fruits showed antiviral activities against her-
pes simplex virus type 1, Para influenza virus type 3, and
polio virus type 1 both in the in vivo and in vitro studies
(Juven and Henis, 1970).
Quercetin, morin, rutin, dihydroquercetin (taxifolin),
apigenin, catechin, and hesperidine have been reported to
possess antiviral activity against some of the 11 types of
viruses (Selway, 1986). The antiviral activity appears to
be associated with the nonglycosidic compounds, and hy-
droxylation at the 3-position is apparently a prerequisite for
antiviral activity.
A study on caffeic acid and chlorogenic acids' antivi-
ral activity against herpes viruses (HSV-1 and HSV-2) and
adenoviruses (ADV-3, ADV-8, and ADV-11) showed caf-
feic acid to have strong antiviral activity against HSV-1 and
HSV-2, whereas chlorogenic acid possessed the strongest
anti-ADV-11 activity. Caffeic acid mode of action against
HSV-2 and ADV-3 was found to be at multiplication stages,
and with Selective Index (SI) values greater than 400, it was

HEALTH FUNCTIONALITY OF
PHYTOCHEMICALS/BIOACTIVE COMPOUNDS

Antimicrobial properties
Phenolics
Phenolic compounds are known to possess both antioxi-
dant and antimicrobial properties. However, the lipophilic
nature of phenols may reduce their antimicrobial properties
(Baranowski and Nagel, 1984). Gallic, p -hydroxybenzoic
acids, and related phenolics does retard or partially inhibit
the growth and toxin production of Clostridium botulinum
types A and B and the inhibitory activity increase with de-
crease in the bacterial concentration (Horowitz and Gentili,
1969). Hydroxycinnamates, which are widely distributed
as secondary metabolites in plants, exhibit a considerable