Differential Effects of Foods Traditionally Regarded as ‘Heating’ and ‘Cooling’ on Prostaglandin E₂ Production by a Macrophage Cell Line

Abstract

Some components of natural foods may enhance or inhibit prostaglandin formation and potentially affect the inflammation condition. A macrophage cell line, RAW264.7, was employed to examine the effects of foods traditionally regarded as ‘heating’ or ‘cooling’ on the production of PGE₂, a well-known proinflammatory mediator. Foods traditionally regarded as ‘heating’ (litchi, longan, and dried longan) or ‘cooling’ (chrysanthemum flower, bitter gourd, and lotus seed plumule) were extracted sequentially with water and ethyl acetate. The water extracts (WE) and ethyl acetate extracts (EAE) were applied to RAW264.7 macrophages in the presence or absence of LPS (lipopolysaccharide). In the absence of LPS, the WEs from the ‘heating foods’, litchi, longan, or dried longan had a dose-dependent enhancing effect on PGE₂ production, with respective EC₅₀s of 8.4, 16, and 11 mg/ml. This effect was accompanied by significant induction of COX-2 protein expression, as shown by Western blot analysis. In contrast, LPS-induced PGE₂ production was inhibited in a dose-dependent manner by the WEs of the ‘cooling foods’, chrysanthemum flower, bitter gourd, and lotus seed plumule, with respective IC₅₀s of 0.6, 0.13, and 0.08 mg/ml. At the concentrations tested, none of the EAEs had any effect on basal PGE₂production, while LPS-induced PGE₂ production was inhibited or increased by the EAE from bitter gourd and longan, respectively. Water-soluble extracts of foods traditionally regarded as ‘heating’ enhanced basal PGE₂ production, while those from ‘cooling’ foods significantly inhibited LPS-induced PGE₂ production by the macrophage cell line. This subject merits further study to determine whether appropriate food selection may help patients suffering from chronic inflammatory conditions.

Exotic fruits as therapeutic complements for diabetes, obesity and metabolic syndrome

“…The 100g edible portion of litchi contains water (81.76 g), protein (0.83 g), lipids (0.44 g), ash (0.44 g), carbohydrates (16.53 g), fiber (1.3g) and sugars (15.23 g) (Table 1). Both in-vitro and in-vivo studies have been conducted exploring the beneficial effects of Litchi, most of which suggest a solid potential for the use of Litchi extract as a supplemental therapeutic to ameliorate diabetes, obesity and its complications (Huang & Wu, 2002; Guo et al, 2004; Obrosova et al, 2010). …”

“…These findings suggest that the Litchi fruit possesses bioactive components that enhance body’s immune system, which can protect from diabetes or obesity induced chronic inflammation. It was further explored that Litchi extract enhances basal prostaglandin E2 (PGE2) production in a macrophage cell line (RAW264.7), which is considered a key inhibitor of the inflammatory immune response (Huang & Wu, 2002). …”

Induction of Apoptosis and Cell Cycle Arrest in Human Colorectal Carcinoma by Litchi Seed Extract

“…Wang and coworkers showed that Litchi pericarp ethanol extract inhibited the in vitro and in vivo growth of mouse hepatocellular carcinoma and both estrogen-dependent and independent human breast carcinoma cells [10, 11]. However, the Litchi pericarp is the edible part of the Litchi fruit, and overdosing may lead to some consumers' uncomfortable “heating” [12]. In recent reports, polyphenol compounds from Litchi seeds were identified and composed of a variety of proanthocyanidins and flavonoid glycoside [13, 14].…”

Isolation and identification of bioactive compounds in Andrographis paniculata (Chuanxinlian)

“…The aerial part of A. paniculata is commonly used in Chinese medicine. According to Chinese medicine theory, A. paniculata 'cools' and relieves internal heat, inflammation and pain and is used for detoxication [4-6]. …”