Biologically active compounds from the genus Uncaria (Rubiaceae)

The species of Uncaria have significant history of traditional medicinal use, for the treatment of many illnesses such as wounds, ulcers, fevers, head-aches, gastrointestinal illness, microbial infections, hypertension, and nervous disorders [6]. Many species of the genus Uncaria, including U. gambir, U. guianensis, U. hirsuta, U. glabrata, U. macrophylla, U. quadrangularis, U. rhynchophylla, U. sinensis, and U. tomentosa have been used as traditional medicine for the treatment of above-mentioned diseases [6]. In traditional medicines of China and Japan, the extracts of many Uncaria species have been used in the herbal formulations to treat various ailments including vascular dementia, epilepsy, and arthritis (Table 1) [8.9]. In 1978, Risdale [7] systematically revised the genus Uncaria and included 34 species in the genus. In the same year, Phillipson et al. [10] extensively studied the alkaloids of Uncaria spp. from approximately 400 herbarium samples collected from across their range of distribution and identified 40 different alkaloids. Subsequently, several classes of compounds including alkaloids, flavonoids, and terpenoids were isolated and identified from this genus [10]. Among these, alkaloids are, however, recognized as the most prominent class of compounds. The phytochemical studies of Uncaria spp. for isolation of bioactive compounds started several decades ago [11]. Rhynchophylline (1.1) is one of the earliest reported compounds from U. rhynchophylla [11]. The present review also presents a comprehensive phytochemical and pharmacological data on this genus. The aim of the present review is to systematically summarize the therapeutic importance of different species of Uncaria, their derived phytochemicals and structure-activity relationship of the isolated compounds in order to explore further research on Uncaria species.