Hydnocarpus: an ethnopharmacological, phytochemical and pharmacological review

The genus Hydnocarpus (Flacourtiaceae) includes forty species that are spread across the globe. In the Indian System of Medicine, Hydnocarpus pentandrus (Buch.-Ham.) Oken. is primarily used for treating leprosy and other skin disorders. It is known as "Chaulmoogra" and is also used to treat other indications including constipation, inflammation, blood disorders, and worm infestations. Various species of Hydnocarpus are also used in traditional medicine in China, Thailand, Malaysia, and Myanmar for several skin disorders. To assess the therapeutic potential of species from the Hydnocarpus genus and to determine future avenues for research.

All relevant scientific literature published up to the end of December 2013 was retrieved via a library and electronic search (SciFinder, PubMed, ScienceDirect, and Google Scholar). Manual searches of traditional books like to ancient classics, including Vaidya Yoga Ratnavali, Siddha Materia Medica, and contemporary references including The Ayurvedic Pharmacopoeia of India and The Ayurveda Formulary, were also performed.

Seed oil from species of the Hydnocarpus genus is used for medicinal purposes, predominantly for various skin disorders. This oil is reported to contain a characteristic class of compounds known as cyclopentenyl fatty acids. Furthermore, seeds of this genus are reported to contain triglycerides of fatty acids, sterols, flavonoids, and flavonolignans. Hydnocarpin, a flavonolignan, is reported to potentiate antimicrobial and anticancer activity. The extracts and compounds isolated from this plant show a wide spectrum of pharmacological properties, including antibacterial, antileprotic, antitubercular, antipsoriatic, antirheumatic, hypolipidemic, antidiabetic, anticancer, anti-inflammatory, and antioxidant activities. The antileprotic activity is postulated to be due to the cyclopentenyl fatty acids present in the seed oil.

Flavonolignans have an interesting chemical motif, and hydnocarpin and its congeners should be investigated for their activities and the mechanism underlying these activities. Multi-drug-resistant microbes are on the increase, and the possible inhibitory effect of these compounds when used with current antimicrobials should also be evaluated. Furthermore, unique cyclopentenyl fatty acids should also be investigated to understand the exact mechanism of action underlying antileprotic activity. Additional in depth phytochemical investigations of seed oil and extracts are required to tap the true potential of species from the Hydnocarpus genus.