Plants comprising bioactive substances with therapeutic value have progressively become the object of research studies. Many species of the genus Alpinia provide a variety of medicinal properties. This study was undertaken to study the biological activities and physicochemical properties of rhizomes and leaves of six Alpinia species available in Sri Lanka namely, Alpinia malaccensis, Alpinia calcarata, Alpinia galanga, Alpinia nigra, Alpinia calcarata Wild and Alpinia purpurata. Physicochemical parameters will be helpful in standardization for quality, purity and authentication of these medicinal plants. Methanol extracts from rhizomes and leaves were screened for total polyphenol content (TPC), antioxidant activity and α-amylase inhibition activities. Extracted powders were analysed for physicochemical constants such as loss on drying, total ash, acid -insoluble ash and water-soluble ash contents. The TPC of dried leaves of Alpinia calcarata Wild was the highest of all tested as 2.186±0.027 g of GA equivalents per 1 g of dried rhizome. The Methanol extracts of the rhizome and leaf samples of six species showed reasonable antioxidant activity in the DPPH radical scavenging assay. Interestingly the rhizome extracts of Alpinia nigra and Alpinia purpurata exhibited higher α-amylase inhibitory activities (29.417±0.507 and 29.676 ± 0.107 µg/mL respectively) compared with the Acarbose, which is an anti-diabetic drug (28.273 ± 0.615 µg/mL). The results revealed that the Sri Lankan Alpinia species have a potency to be used as a source of antioxidant and anti-diabetic agents and it is important to increase the value of the unexplored medicinal herbs available in Sri Lanka.

Background: Pavetta indica Linn is a medicinal plant that belongs to the family of Rubiaceae. The parts of this plant are used in indigenous clinical practices, especially for treating visceral obstruction, haemorrhoidal pains, rheumatism and eye diseases, and in the preferential treatment of liver disease, pain from piles, urinary infections, and fever. Despite its usage in indigenous clinical practices, there is limited available information on comparative pharmacognostic, physicochemical, phytochemical, ethnopharmacological data and antioxidant capacity of this herb. Aim: To review and summarize the medicinal properties of Pavetta indica Linn after critically evaluating the published studies reporting and to identify potential research areas from the existing data. Methodology: In the first phase, a comprehensive literature search was carried out in several databases under the PRISMA (Preferred Reporting Project for Systematic Reviews and Meta-Analysis) guidelines. Results: The plant reported various classes of bioactive compounds with the main components: carbohydrates, glycosides, alkaloids, phytosterols, saponins, tannins, proteins and amino acids, phenolic and flavonoids. Extracts of this plant possess multiple pharmacological activities such as hepatoprotective, anti-inflammatory, antioxidant, antidiabetic, neuroprotective and wound healing factors, anti-dementia, anti-cancer, antimicrobial, antihelminthic and diuretic properties. Conclusion: This review gives vital information on the traditional uses and, on the other hand, modern discoveries such as phytochemistry and pharmacology of Pavetta indica Linn. The therapeutic value of the plant was discovered based on the information gathered during the review process. As a result, greater research on this plant should be encouraged to identify new useful drugs and therapeutic effects and test using clinical studies.