The next experiment was conducted to study the inhibitory effect of the plant extracts on pro-inflammatory cytokine
synthesis (Table 3). The result showed that the concentration of TNF-α in culture supernatant without a stimulant was
8.54 pg/ml. There was an increase in the production of pro-inflammatory cytokines, TNF-α, up to 112.87 pg/ml when
stimulated with heat-killed P. acnes, while the positive control, zymosan showed an increase in the production of TNF-
α up to 78.71 pg/ml. The result implied that P. acnes could stimulate the pro-inflammatory cytokines and also played
an important role in the pathogenesis of inflammatory acne.