Graphical abstract

The leaves of the endemic Philippine plant, Dillenia philippinensis yielded 11 compounds including one new sulfated glucoside and a new seco-A-ring oleanane-type triterpenoid. The molecular structures of these compounds were elucidated by means of NMR, MS and other spectroscopic techniques, as well as by comparison with literature data. Anti-Leishmania activity and cytotoxic activity against A549 human lung adenocarcinoma cells were also examined.

Phytochemical investigation of the dried leaves of Fraxinus griffithii collected in Okinawa has led to the isolation of three new secoiridoid glucosides, griffithosides A-C (1-3), and one new iridoid glucoside, 7-epi-7-O-(E)-caffeoylloganic acid (4), along with eight known secoiridoid glucosides (5-12). The structures of these compounds were elucidated by means of NMR, MS, and other spectroscopic techniques, as well as comparison with literature data. The isolated compounds were tested for radical-scavenging activity. Among them, compounds 3, 4, and 7 exhibited substantial radical-scavenging activity.

Coronavirus disease 2019 (COVID-19) continues to devastate the world’s health and economy, affecting all aspects of life leading to widespread social disruption. Even as several vaccines have been developed, their availability in developing countries is limited and their efficacy against the variants of SARS-CoV-2 (severe acute respiratory syndrome–coronavirus 2) needs to be continuously assessed. The World Health Organization (WHO) has acknowledged that vaccines alone will not overcome the global challenges of COVID-19. Medicinal plants may provide the needed support. Herein, we identify Philippine medicinal plants that possess phytochemicals with potential anti-SARS-CoV-2 activity and/or immunomodulatory properties that may strengthen one’s immune system against COVID-19. These plants were selected from 100 of the best-studied Philippine medicinal plants with antiviral and immunomodulatory properties. The general antiviral and specific anti-SARS-CoV-2 activities and immunomodulatory properties of the phytochemicals that these plants contained were searched. While many compounds assessed individually using in vitro and in silico techniques suggest potential anti-SARS-CoV-2 or immunomodulatory effects, this review sought to identify the medicinal plants which contain these compounds and which, based on literature, have the best potential application against COVID-19. These plants are Allium spp. bulbs (bawang), Andrographis paniculata (Burm.f.) Nees leaves (sinta), Cocos nucifera L. oil (niyog), Euphorbia hirta L. leaves (tawa-tawa), Euphorbia neriifolia L. leaves (sorosoro), Moringa oleifera Lam. leaves (malunggay), Ocimum basilicum L. leaves (balanoy), Piper nigrum L. seeds (paminta), Vitex negundo L. leaves (lagundi), and Zingiber officinale Roscoe rhizome (luya). This review provides a shortlist that can guide research on possible solutions to COVID-19 using Philippine medicinal plants.

Phytochemical investigation of the leaves of Fraxinus griffithii has led to the isolation of two new glucosylated acyclic sesquiterpene alcohols, griffithosides D (1) and E (2), along with iridoid and secoiridoid glycosides. The molecular structures of these compounds were elucidated using NMR, MS and other spectroscopic techniques, as well as comparison with literature data. The isolated compounds were tested for radical-scavenging activity and cytotoxicity against A549 human lung adenocarcinoma cells and Leishmania major parasites.