somewhat similar to alcohol and benzodiazapines but without many of the negative side effects and less of an addiction risk. It has also become popular elsewhere in recent decades, and is used as a medical plant. However, pills that contain parts of the whole plant have occasionally shown a strong hepatotoxic effect, which has led to the banning of kava in many countries. On the other hand, the traditional preparation of the root as a calming drink appears to pose little, if any, such hazard. In science The genus contains species suitable for studying natural history, molecular biology, natural products chemistry, community ecology, and evolutionary biology. Piper is a model genus for research in ecology and evolutionary biology. The diversity and ecological importance of the genus makes it a strong candidate for ecological and evolutionary studies. Most research has focused on the economically important species P. nigrum (black pepper), P. methysticum (kava), and P. betle (betel). A recent study based on DNA sequence analysis suggest that P. nigrum originated in the Western Ghats hot spot in India. The obligate and facultative ant mutualists found in some Piper species have a strong influence on their biology, making them ideal systems for research on the evolution of symbioses and the effect of mutualisms on biotic communities. Important secondary metabolites found in pepper plants are piperine and chavicine, which were first isolated from Black Pepper, and reported to have antibiotic activities. Preliminary research reports has shown that piperine has an antibacterial activity against various bacteria such as S. aureus, Streptococcus mutans, and gastric cancer pathogen Helicobacter pylori and decreased H. pylori toxin entry to gastric epithelial cells. The piperidine functional group is named after the former, and piperazine (which is not found in P. nigrum in noticeable quantities) was in turn named after piperidine. The significant secondary metabolites of kava are kavalactones and flavokawains. Pipermethystine is suspected to be the main hepatotoxic compound in this plant's stems and leaves. Species The largest number of Piper species are found in the Americas (about 700 species), with about 300 species from Southern Asia. There are smaller groups of species from the South Pacific (about 40 species) and Africa (about 15 species). The American, Asian, and South Pacific groups each appear to be monophyletic; the affinity of the African species is unclear. Some species are sometimes segregated into the genera Pothomorphe, Macropiper, Ottonia, Arctottonia, Sarcorhachis, Trianaeopiper,